Microbiology
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Questions and Answers

Which of the following is NOT one of Koch’s Postulates?

  • The organism must cause disease when introduced to a healthy host
  • The organism must be easily identifiable under a microscope (correct)
  • The organism must be isolated and grown in pure culture
  • The organism must be present in every case of the disease
  • What is described as a crucial step in confirming a microbial infection according to Koch's Postulates?

  • Determining antibiotic resistance profile
  • Isolating the pathogen from wastewater
  • Observing symptoms in an untreated population
  • Recovering the organism from an infected individual (correct)
  • In the context of Koch's Postulates, which statement best describes the relationship between the host and the pathogen?

  • A pathogen must be capable of causing disease in a healthy host (correct)
  • Infection occurs exclusively through direct contact with contaminated surfaces
  • Healthy hosts only transmit diseases through vectors
  • All pathogens naturally exist in healthy organisms without causing harm
  • Which of the following methods could challenge the second postulate regarding the isolation of pathogens?

    <p>Culturing bacteria that are not easily grown outside of the host (C)</p> Signup and view all the answers

    Which aspect of pathogen transmission is emphasized in Koch's Postulates?

    <p>Pathogens must be recoverable after causing disease (C)</p> Signup and view all the answers

    What process describes how an organism spreads within a population?

    <p>Transmission (A)</p> Signup and view all the answers

    What is the first step for a microorganism in causing an infection?

    <p>Gaining access to the host (C)</p> Signup and view all the answers

    Which of the following is a primary reason for identifying the organism causing a disease?

    <p>To develop appropriate treatment strategies (B)</p> Signup and view all the answers

    Which method involves removing or killing pathogens after an infection?

    <p>Antibiotic therapy (C)</p> Signup and view all the answers

    In host-pathogen interactions, which factor is crucial for the pathogen to successfully establish an infection?

    <p>Pathogen virulence factors (A)</p> Signup and view all the answers

    What was one significant finding from Koch's research on anthrax?

    <p>Bacillus anthracis can be found in domestic animals. (D)</p> Signup and view all the answers

    What is one common mode of pathogen transmission?

    <p>Respiratory droplets (B)</p> Signup and view all the answers

    Which method did Koch use to demonstrate that Bacillus anthracis caused anthrax?

    <p>He injected healthy animals with pure cultures. (B)</p> Signup and view all the answers

    What is one of the key aspects of infectious disease discussed?

    <p>How the organism spreads within a population. (D)</p> Signup and view all the answers

    Which technique is often used for identifying specific microorganisms in a laboratory?

    <p>PCR (Polymerase Chain Reaction) (A)</p> Signup and view all the answers

    What does the ability of a microorganism to cause disease primarily depend on?

    <p>Host immune response (C)</p> Signup and view all the answers

    What is a critical step in eliminating an organism after an infection?

    <p>Using antibiotics or disinfectants effectively. (C)</p> Signup and view all the answers

    How did Koch confirm the presence of bacterial cells in infected blood?

    <p>By using a microscope. (A)</p> Signup and view all the answers

    In the context of host-pathogen interaction, which statement is accurate?

    <p>Pathogens must gain access to the host to cause disease. (C)</p> Signup and view all the answers

    Which of the following refers to how a microorganism spreads throughout a population?

    <p>Infectious disease transmission. (A)</p> Signup and view all the answers

    What type of bacteria is Bacillus anthracis classified as?

    <p>Gram-positive and rod-shaped. (A)</p> Signup and view all the answers

    What is a significant characteristic of spore-forming bacteria like Bacillus anthracis?

    <p>They can remain dormant for long periods in adverse conditions. (C)</p> Signup and view all the answers

    What type of genes are primarily found on bacterial plasmids?

    <p>Luxury genes, including those for antibiotic resistance. (C)</p> Signup and view all the answers

    How does Bacillus anthracis commonly infect animals after spore germination?

    <p>By producing toxins that cause severe illnesses. (A)</p> Signup and view all the answers

    What happened to Gruinard Island after the anthrax testing in 1942?

    <p>It was treated with formaldehyde and later declared fit for habitation. (C)</p> Signup and view all the answers

    Why do bacteria typically lack introns in their genetic structure?

    <p>Bacteria do not undergo splicing processes. (B)</p> Signup and view all the answers

    What is the primary method by which bacteria can acquire new genetic material?

    <p>Transformation, conjugation, and transduction (B)</p> Signup and view all the answers

    What type of organisms can survive in soil for extended periods of time due to their sporulating ability?

    <p>Both pathogenic and non-pathogenic bacteria (D)</p> Signup and view all the answers

    How do bacterial genomes typically compare to those of eukaryotes?

    <p>Bacterial genomes are smaller and more streamlined. (A)</p> Signup and view all the answers

    What was the immediate effect of the anthrax testing conducted on Gruinard Island in 1942?

    <p>Sheep began to die after three days of testing. (C)</p> Signup and view all the answers

    What does the ability of bacteria to respond quickly to environmental changes primarily involve?

    <p>Changes in gene expression levels. (D)</p> Signup and view all the answers

    What role do plasmids play in bacterial conjugation?

    <p>They are involved in the transfer of genetic material. (C)</p> Signup and view all the answers

    Which statement best describes bacteriophages?

    <p>They specifically target and kill bacterial cells. (C)</p> Signup and view all the answers

    What process allows for the transfer of DNA from one bacterium to another via a bacteriophage?

    <p>Transduction (B)</p> Signup and view all the answers

    Which of the following describes a therapeutic application of bacteriophages?

    <p>Treatment of bacterial infections like dysentery. (D)</p> Signup and view all the answers

    What is a common characteristic of Gram-negative bacteria?

    <p>Presence of an outer membrane. (A)</p> Signup and view all the answers

    Which characteristic is unique to endospores?

    <p>High resistance to environmental stress. (C)</p> Signup and view all the answers

    What aspect of bacterial identification is crucial to effective treatment?

    <p>Identifying the causative pathogen. (B)</p> Signup and view all the answers

    Which factor is NOT typically considered when selecting growth media for bacterial cultures?

    <p>Cost of media ingredients. (C)</p> Signup and view all the answers

    What type of media helps to differentiate between different types of bacteria?

    <p>Differential media (D)</p> Signup and view all the answers

    Which bacterium is associated with endospore formation?

    <p>Clostridium tetani (A)</p> Signup and view all the answers

    Which organism is NOT listed among the notifiable diseases?

    <p>Staphylococcus aureus (A)</p> Signup and view all the answers

    What method is commonly used for the microscopic identification of bacteria?

    <p>Microscopic morphology assessment (D)</p> Signup and view all the answers

    What is the primary function of the Gram stain in diagnostic microbiology?

    <p>To classify bacteria based on their cell wall structure. (A)</p> Signup and view all the answers

    Which of the following is a characteristic feature of Bacteriophage therapy?

    <p>It exploits the natural ability of viruses to kill bacteria. (A)</p> Signup and view all the answers

    What is a characteristic feature of bacteria that distinguishes them from eukaryotic cells?

    <p>Being prokaryotic organisms (C)</p> Signup and view all the answers

    Which of the following bacteria is commonly associated with hospital-acquired infections?

    <p>Klebsiella pneumoniae (D)</p> Signup and view all the answers

    Which characteristic differentiates non-lactose fermenting bacteria on Salmonella-Shigella agar?

    <p>Production of hydrogen sulfide (A)</p> Signup and view all the answers

    What color change indicates lactose fermentation in Klebsiella pneumoniae and Citrobacter freundii on agar plates?

    <p>From yellow to red (B)</p> Signup and view all the answers

    What property do Gram-negative bacteria generally exhibit compared to Gram-positive bacteria?

    <p>Presence of an outer membrane (B)</p> Signup and view all the answers

    Which species of bacteria is known for causing typhoid fever?

    <p>Salmonella enterica subsp. enterica Typhi (C)</p> Signup and view all the answers

    What happens to the color of neutral red in agar when a non-lactose fermenting bacterium grows?

    <p>It turns from red to yellow (C)</p> Signup and view all the answers

    Which of the following is a true statement about the nature of bacterial chromosomes?

    <p>Most bacteria have a single chromosome. (D)</p> Signup and view all the answers

    What is one of the acute symptoms of toxoplasmosis?

    <p>Blindness (A)</p> Signup and view all the answers

    Which of the following best describes the transmission method of leishmaniasis?

    <p>Bites from infected female sand flies (B)</p> Signup and view all the answers

    What treatment is typically used for visceral leishmaniasis?

    <p>Sodium stibogluconate (D)</p> Signup and view all the answers

    How many people does malaria infect each year approximately?

    <p>200 million (B)</p> Signup and view all the answers

    What is the mechanism of infection by the malaria parasite in humans?

    <p>Bite by infected Anopheles mosquito (D)</p> Signup and view all the answers

    Which of the following symptoms is associated with malaria?

    <p>Periodic fevers every 48-72 hours (C)</p> Signup and view all the answers

    What is the main protozoa responsible for causing malaria?

    <p>Plasmodium (B)</p> Signup and view all the answers

    Which method is NOT a known preventative measure against malaria?

    <p>Consumption of herbal remedies (A)</p> Signup and view all the answers

    Which drug is commonly used for prophylactic treatment against malaria?

    <p>Mefloquine (B)</p> Signup and view all the answers

    What is one reported behavioral change associated with toxoplasmosis?

    <p>Increased risk-taking (C)</p> Signup and view all the answers

    What defines the appearance of filamentous fungi?

    <p>They typically have a 'hairy' appearance. (C)</p> Signup and view all the answers

    What is a major component of the fungal cell wall that distinguishes it from mammalian cells?

    <p>Chitin (B)</p> Signup and view all the answers

    Which fungal infection affects the surface layer of skin, nails, or hair?

    <p>Tinea (ringworm) (B), Candidiasis (A)</p> Signup and view all the answers

    Which type of protozoa causes malaria?

    <p>Plasmodium falciparum (D)</p> Signup and view all the answers

    What is the structure formed by the branched formation of hyphae in filamentous fungi called?

    <p>Mycelium (B)</p> Signup and view all the answers

    Which of the following is an antifungal target that distinguishes fungi from mammals?

    <p>Ergosterol in the cell membrane (C)</p> Signup and view all the answers

    What type of replication can protozoa utilize?

    <p>Both sexual and asexual replication (C)</p> Signup and view all the answers

    Which statement accurately reflects the severity of protozoan infections?

    <p>Severity can vary based on the route of infection. (C)</p> Signup and view all the answers

    What is the generic term for fungal infections?

    <p>Mycosis (C)</p> Signup and view all the answers

    What distinguishes the cell membrane composition of fungi from mammals?

    <p>Presence of ergosterol (A)</p> Signup and view all the answers

    Which form of reproduction is common in filamentous fungi?

    <p>Both sexual and asexual reproduction (C)</p> Signup and view all the answers

    What type of fungal infections are most likely to be unpleasant but seldom fatal?

    <p>Superficial infections (D)</p> Signup and view all the answers

    Which of the following is NOT a class of protozoa?

    <p>Myceliates (A)</p> Signup and view all the answers

    What is a primary characteristic of Trichomonas vaginalis infections in females?

    <p>Infection generally occurs in the cervical area of the vagina or the urethra (B)</p> Signup and view all the answers

    Which organism is responsible for causing Cryptosporidiosis?

    <p>Cryptosporidium parvum (B)</p> Signup and view all the answers

    What is a common route of transmission for Giardia lamblia?

    <p>Contaminated food and water (A)</p> Signup and view all the answers

    Which symptom is commonly associated with infections caused by Entamoeba histolytica?

    <p>Amoebic dysentery (B)</p> Signup and view all the answers

    What significance does Metronidazole hold in treating certain infections?

    <p>It is a general inhibitor of DNA replication (B)</p> Signup and view all the answers

    What is the main source of infection for Toxoplasma gondii?

    <p>Contaminated meat or cat feces (B)</p> Signup and view all the answers

    Which of the following is a common symptom of Trichomoniasis?

    <p>Unpleasant 'fishy' smell in discharge (C)</p> Signup and view all the answers

    What characteristic is often seen in infections caused by Cryptosporidium parvum?

    <p>Severe diarrhea lasting 2-7 days (A)</p> Signup and view all the answers

    In what part of the body does Giardia lamblia primarily attach during infection?

    <p>Duodenal wall (D)</p> Signup and view all the answers

    What is a notable property of Trichomonas vaginalis in terms of symptom presentation?

    <p>Many males often remain asymptomatic (B)</p> Signup and view all the answers

    How does Entamoeba histolytica cause damage within the gastrointestinal tract?

    <p>By disrupting the mucosal structure, leading to ulceration (A)</p> Signup and view all the answers

    What is the estimated annual number of Trichomonas vaginalis cases globally?

    <p>About 160 million cases (D)</p> Signup and view all the answers

    Which of the following describes a primary vector for T.brucei gambiense?

    <p>Tsetse fly (C)</p> Signup and view all the answers

    What is a significant consequence of the widespread resistance to oseltamivir in treating influenza?

    <p>Greater reliance on non-antiviral treatments. (D)</p> Signup and view all the answers

    What is the main difference between antigenic drift and antigenic shift in influenza viruses?

    <p>Drift occurs in one viral strain, while shift involves multiple strains. (B)</p> Signup and view all the answers

    What level of vaccine uptake is generally considered necessary for effective herd immunity?

    <p>95% (D)</p> Signup and view all the answers

    What is a primary factor that complicates vaccination efforts for influenza?

    <p>The genetic fluidity of the virus. (B)</p> Signup and view all the answers

    Which of the following is true regarding the availability of vaccines and antiviral treatments for viral diseases listed?

    <p>HIV has no vaccine but has antiviral treatments. (B)</p> Signup and view all the answers

    What complicates the vaccination program for specific populations, such as the elderly?

    <p>Lower immune response in older individuals. (B)</p> Signup and view all the answers

    What is the main problem related to the uptake of vaccinations in the context of outbreaks?

    <p>A critical percentage of the population opting out of vaccination. (B)</p> Signup and view all the answers

    How does geographical isolation function as a control measure for infections?

    <p>Its effectiveness highly relies on enforcement capabilities. (D)</p> Signup and view all the answers

    What is the typical fatality rate for Ebola virus infections?

    <p>50% (A)</p> Signup and view all the answers

    Which country had the highest number of Ebola cases during the 2014 outbreak?

    <p>Liberia (C)</p> Signup and view all the answers

    What action was taken when the girl in Bombali showed symptoms of Ebola?

    <p>She was isolated in an Ebola treatment centre. (A)</p> Signup and view all the answers

    What was a significant reason for the spread of Ebola in Sierra Leone?

    <p>Lack of adherence to imposed restrictions. (D)</p> Signup and view all the answers

    What role do animal reservoirs play in the transmission of the Ebola virus?

    <p>They act as carriers that infect humans. (D)</p> Signup and view all the answers

    What was the first reported EVD-free week in Guinea during the 2014 outbreak?

    <p>15th September 2015 (C)</p> Signup and view all the answers

    How many deaths were reported in Liberia during the 2014 Ebola outbreak?

    <p>4805 (D)</p> Signup and view all the answers

    During which outbreak did new cases of Ebola continue to occur regularly?

    <p>2014 outbreak (A)</p> Signup and view all the answers

    What was the link among the majority of cases in Sierra Leone during the outbreak?

    <p>Previous contact with affected individuals. (B)</p> Signup and view all the answers

    What is an effective response action taken to control the spread of Ebola?

    <p>Immediate isolation of infected individuals. (A)</p> Signup and view all the answers

    What is the primary way to prevent Zika virus disease (ZVD)?

    <p>Avoiding mosquito bites (C)</p> Signup and view all the answers

    Which of the following symptoms is typically associated with Zika virus disease?

    <p>Mild fever and rash (D)</p> Signup and view all the answers

    What type of virus are coronaviruses classified as?

    <p>RNA viruses (D)</p> Signup and view all the answers

    What is a significant characteristic of the influenza virus structure?

    <p>Spherical viral particles (C)</p> Signup and view all the answers

    What type of transmission is primarily responsible for spreading the influenza virus?

    <p>Airborne transmission via aerosols (B)</p> Signup and view all the answers

    What is one of the long-term concerns associated with infections from viruses like Zika?

    <p>Possibility of microcephaly in newborns (C)</p> Signup and view all the answers

    Which factor is crucial for the influenza virus to successfully infect a host?

    <p>Presence of glycoproteins for cell recognition (D)</p> Signup and view all the answers

    Which of the following describes the mosquito species responsible for Zika virus transmission?

    <p>Aedes aegypti (A)</p> Signup and view all the answers

    What is a common long-term effect of viral infections like those caused by coronaviruses?

    <p>Development of secondary bacterial infections (D)</p> Signup and view all the answers

    What mechanism does the influenza virus use to release new viral particles after replication?

    <p>Utilization of neuraminidase (B)</p> Signup and view all the answers

    What characteristics are typical of the influenza viral genome?

    <p>Single stranded RNA (D)</p> Signup and view all the answers

    What is the primary effect of the Zika virus on neonates if the mother is infected during pregnancy?

    <p>Potential for birth defects like microcephaly (B)</p> Signup and view all the answers

    What factor is identified as significant in the transmission of vector-borne diseases like Zika and dengue?

    <p>Environmental conditions such as temperature and humidity (C)</p> Signup and view all the answers

    What is a common treatment method for managing HCMV infections?

    <p>Ganciclovir administration (C)</p> Signup and view all the answers

    Flashcards

    Koch's Postulates

    A set of criteria for proving that a specific microorganism causes a specific disease.

    Koch's Postulate 1

    The microbe must be found in every case of the disease.

    Koch's Postulate 2

    The microbe can be grown in a lab in a pure culture.

    Koch's Postulate 3

    The microbe, when introduced to a healthy animal, causes the illness.

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    Koch's Postulate 4

    The same microbe must be isolated from the diseased animal

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    Microorganisms and Disease

    Microorganisms play a vital role in the development of infectious diseases.

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    Spread of Microorganisms

    Microorganisms can spread within populations through various mechanisms like contact, air, or vectors.

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    Gaining Access to the Host

    Microorganisms need specific pathways to enter and infect the host.

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    Causing Disease

    Microorganisms cause disease by disrupting normal host functions and causing illness.

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    Identifying the Culprit

    Identifying the specific microorganism responsible for a disease is crucial for treatment.

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    Eliminating the Organism

    Treatments aim to eliminate or control the harmful microorganism to cure the disease.

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    What does this lecture cover?

    This lecture explains the role of microorganisms in infectious disease, including their spread, access to the host, disease causation, identification, and elimination.

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    What is the focus of this course?

    This course aims to understand how microorganisms cause disease and the methods to identify and eliminate them.

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    Who is Robert Koch?

    Robert Koch was a German physician who made groundbreaking discoveries in the field of microbiology, particularly, identifying the bacteria responsible for anthrax. He was a pioneer in the development of germ theory and his work paved the way for understanding infectious diseases.

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    What is Bacillus anthracis?

    Bacillus anthracis is a rod-shaped, gram-positive bacterium that causes the disease anthrax. It is commonly found in soil and can affect animals and humans.

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    How did Koch identify Bacillus anthracis?

    Koch identified Bacillus anthracis by collecting blood from infected cattle, observing the bacteria under a microscope, and injecting the infected blood into healthy animals. He also cultivated the bacteria in pure culture and proved its role in causing anthrax by injecting these cultures into healthy animals.

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    What did Koch's work on anthrax demonstrate?

    Koch's work demonstrated the crucial link between specific microorganisms and infectious diseases. It laid the foundation for the germ theory of disease, which revolutionized our understanding of how diseases are caused and spread.

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    Why is Koch's work important?

    Koch's work on anthrax was a landmark achievement in medical microbiology. It established a scientific method for identifying the cause of infectious diseases. His work solidified the germ theory and marked a crucial turning point in our understanding of disease pathogenesis.

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    What is the significance of Koch's publication in 1876?

    Koch's publication in 1876 detailed his groundbreaking discovery of Bacillus anthracis and its role in causing anthrax. This paper, written in German, remains a historical document that shaped the field of medical microbiology and is still accessible today.

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    Why is it possible to access Koch's original work?

    The original publication of Koch's work on anthrax is still available, demonstrating the enduring importance of scientific documentation. This accessibility allows us to learn about the scientific process, the historical context, and the development of medical microbiology.

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    How does Koch's work relate to the germ theory of disease?

    Koch's work provided strong evidence for the germ theory of disease, which states that specific microorganisms are responsible for causing specific diseases. His methods for identifying and proving the causal role of Bacillus anthracis became the foundation for the germ theory.

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    Anthrax Spores

    Dormant, highly resistant forms of Bacillus anthracis that can survive in harsh environments for extended periods.

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    Anthrax and Soil

    Bacillus anthracis, the bacterium responsible for anthrax, can survive in soil for extended periods, making it a potential source of infection.

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    Why is Protective Clothing Important when working with Anthrax?

    Anthrax spores are highly infectious, and exposure can lead to severe illness. Protective clothing helps minimize the risk of infection.

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    Gruinard Island Experiment

    During World War II, scientists conducted biological warfare experiments on Gruinard Island using Bacillus anthracis.

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    Consequences of the Gruinard Island Experiment

    The experiment resulted in the island's contamination with anthrax. It took extensive decontamination efforts before the island could be declared safe for habitation.

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    Bacterial Genomes

    Bacteria possess relatively small and compact genomes compared to eukaryotic organisms.

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    Why do bacteria rarely use introns?

    Introns are non-coding regions of DNA that are removed during RNA processing. Bacteria have streamlined genomes with minimal redundancy.

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    Bacterial Adaptation

    Bacteria can quickly respond to environmental changes by altering their gene expression levels.

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    Key Components of Bacterial Genetics

    The primary genetic material in bacteria is a single chromosome. However, they can also harbor additional genetic elements called plasmids.

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    Plasmids: Non-Essential Genes

    Plasmids are small, circular DNA molecules that often carry genes that are not essential for survival, but can provide advantages like antibiotic resistance or virulence.

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    What does a bacterium lack?

    Bacteria are prokaryotic cells, meaning they lack a true nucleus.

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    Are all bacteria the same?

    Bacteria can vary significantly in appearance. Their shapes and colors differ on agar plates, making them recognizable.

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    How are bacteria visualized?

    Bacteria are too small to be seen with the naked eye. They are grown in colonies on agar plates for visualization.

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    What's a prokaryote?

    A prokaryote is a single-celled organism lacking a nucleus and other membrane-bound organelles. Bacteria are prokaryotes.

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    How many chromosomes do bacteria usually have?

    Most bacteria have one chromosome, though exceptions do exist.

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    What are enteric pathogens?

    Enteric pathogens are bacteria that live in the intestines and can cause disease.

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    Salmonella typhimurium

    A type of Salmonella that causes food poisoning.

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    What is Agar Art?

    Agar Art is a form of art made by growing different types of bacteria on an agar plate.

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    Conjugation

    A process where bacteria transfer genetic material (DNA) from one cell to another.

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    What is a plasmid?

    A small, circular DNA molecule found in bacteria, separate from the main bacterial chromosome, that can replicate independently.

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    F+ strain

    A bacterial cell that carries a fertility (F) plasmid, which allows it to donate DNA during conjugation.

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    F- strain

    A bacterial cell that lacks the fertility (F) plasmid and can receive DNA during conjugation.

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    Bacteriophage

    A virus that infects bacteria.

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    Plaques

    Clear areas on a bacterial culture plate where a bacteriophage has killed bacteria.

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    Transduction

    The process where a bacteriophage transfers bacterial DNA from one cell to another.

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    Bacteriophage Therapy

    The use of bacteriophages to treat bacterial infections.

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    Notifiable Organisms

    Microorganisms that are legally required to be reported to public health authorities.

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    Diagnostic Microbiology

    The branch of microbiology that focuses on identifying and characterizing microorganisms causing infections.

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    What are the steps in organism identification?

    Identifying a microorganism involves using techniques like staining, growing on specific media, and analyzing biochemical properties.

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    Types of Media

    Different growth media are used to cultivate microorganisms, based on factors like oxygen requirements, temperature, pH, and nutrient needs.

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    Selective and Differential Media

    Specialized media used to isolate and identify specific microorganisms from a mixed population.

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    Phenotypic Identification

    The process of identifying a microorganism based on its observable characteristics.

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    Biochemical Phenotype

    The unique biochemical properties of a microorganism used for identification.

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    Toxoplasmosis

    A parasitic infection caused by the protozoan Toxoplasma gondii, which can cause a range of symptoms from mild flu-like illness to severe neurological complications.

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    Leishmaniasis

    A disease caused by parasitic protozoa of the genus Leishmania, transmitted by infected sandflies. It can manifest as cutaneous (skin) or visceral (internal organs) forms.

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    Visceral Leishmaniasis

    A severe form of leishmaniasis that affects the internal organs, particularly the liver, spleen, and bone marrow. It can lead to anemia, weight loss, and death.

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    Malaria

    A serious and sometimes fatal disease caused by parasitic protozoa of the genus Plasmodium, transmitted through the bite of infected Anopheles mosquitos.

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    Malaria Lifecycle

    The complex lifecycle of Plasmodium involves both a mosquito and human host. The parasite undergoes sexual reproduction in mosquitos and asexual reproduction in humans.

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    Malaria Symptoms

    Symptoms of malaria include periodic fevers, chills, headaches, abdominal pain, nausea, and vomiting.

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    Malaria Prevention

    Malaria prevention strategies include vaccination, taking antimalarial drugs before travel, and using mosquito nets and insect repellent.

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    Malaria Treatment

    Treatment for malaria involves antimalarial drugs such as quinine, doxycycline, and artemisinin.

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    Pyrimethamine

    A medication used in combination with other drugs to treat toxoplasmosis.

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    Fungal Cell Wall

    A rigid outer layer of fungi composed mainly of β-glucan, chitin, and mannan, providing structural support and protection.

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    Fungal Growth Temperature

    Most medically important fungi thrive at temperatures between 20°C and 25°C, making them more common outside the human body.

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    Spore Formation

    A reproductive strategy used by filamentous fungi where they produce spores, which can disperse and germinate into new fungi.

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    Yeast

    Unicellular, spherical fungi that reproduce asexually by budding or binary fission.

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    Filamentous Fungi

    Multicellular fungi characterized by their branched, thread-like hyphae that form extensive networks called mycelia.

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    Mycosis

    A fungal infection, categorized into superficial (cutaneous), subcutaneous, and systemic based on the location of infection.

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    Superficial Fungal Infections

    Fungal infections affecting the outer layers of skin, nails, or hair, examples include candidiasis and tinea.

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    Subcutaneous Fungal Infections

    Fungal infections that occur beneath the skin, often in deeper layers.

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    Systemic Fungal Infections

    Fungal infections that spread throughout the body, often affecting internal organs.

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    Ergosterol

    A sterol found in the cell membranes of fungi, crucial for their survival, and a target for antifungal drugs.

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    Antifungal Agents

    Drugs used to treat fungal infections, often targeting ergosterol or other fungal cell components.

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    Protozoa

    Unicellular eukaryotic organisms found in diverse environments, including aquatic habitats and animal digestive systems.

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    Amoeba

    A type of protozoa that moves using pseudopods (temporary extensions of cytoplasm).

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    Ciliates

    Protozoa that move using hair-like structures called cilia.

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    Flagellates

    Protozoa that move using whip-like structures called flagella.

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    Trichomoniasis Transmission

    Trichomoniasis is spread through sexual contact.

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    Trichomoniasis Symptoms

    Trichomoniasis symptoms can include vaginal discharge, itching, burning, and pain during urination or sex. However, many people have no symptoms.

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    Cryptosporidiosis Transmission

    Cryptosporidiosis is spread through contaminated water or faecal-oral contact.

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    Giardiasis Transmission & Location

    Giardiasis is spread through contaminated food and water. The parasite attaches to the duodenal wall.

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    Amebiasis Transmission

    Amebiasis is commonly acquired abroad and spreads through contaminated food and water.

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    Amebiasis Cause & Symptoms

    Entamoeba histolytica causes amoebic dysentery characterized by severe cramps, colitis, and bloody diarrhea.

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    Toxoplasmosis Transmission

    Toxoplasmosis is spread through undercooked meat and direct contact with cat faeces.

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    Toxoplasmosis Symptoms

    Most Toxoplasmosis cases are mild, but in rare cases, it can invade tissues, affecting organs like the lungs, heart, CNS, and eyes.

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    Protozoan Infections: Trichomoniasis, Cryptosporidiosis, Giardiasis, Amebiasis

    These infections are caused by protozoa and are prevalent worldwide. They can cause various symptoms, including diarrhea, genital discharge, and organ invasion.

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    Metronidazole Treatment

    Metronidazole is commonly used to treat Trichomoniasis, Giardiasis, and Amebiasis.

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    Protozoan Infection Entry Routes

    Oral ingestion, sexual transmission, skin cuts, and insect bites are common entry routes for protozoan infections.

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    Protozoan Infection: Attachment Requirement

    Protozoa require physical attachment to human tissue for infection, either directly or indirectly.

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    Protozoan Infection Outcome

    Protozoan infections often lead to chronic conditions that can last for months or years, posing challenges with complications from reinfections.

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    Protozoan Infection: Global Prevalence

    Protozoan infections are a significant health concern globally, with millions of cases reported each year.

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    Protozoan Infection: Common in UK & Elsewhere

    While less common in the UK, they are more prevalent in other parts of the world, highlighting the importance of awareness and prevention.

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    Ebola Virus Disease (EVD)

    A severe, often fatal disease caused by the Ebola virus, characterized by fever, bleeding, and organ failure.

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    EVD Transmission Routes

    Ebola virus spreads through direct contact with infected bodily fluids, including blood, sweat, and saliva.

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    Ebola Outbreak in West Africa (2014-2016)

    The largest Ebola outbreak in history, with Guinea, Liberia, and Sierra Leone being the worst affected countries.

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    Ebola Control Measures

    Effective measures to control Ebola outbreaks include isolating infected individuals, contact tracing, safe burial practices, and public health education.

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    Effectiveness of Border Controls for EVD

    Border controls can help slow down the spread of EVD by limiting travel from affected areas, but they are not effective alone.

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    Ebola Case Study: Bombali, Sierra Leone

    The case of a 16-year-old girl with EVD in Bombali, Sierra Leone, illustrates the challenges of containing the virus.

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    Ebola Response: Rapid-Response Teams

    Ebola treatment centers and rapidly deployed response teams play a crucial role in minimizing the spread of the virus.

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    Possible Problems in Outbreak Control: Non-Compliance

    People who disregard restrictions can contribute to the spread of an outbreak, as seen in the case of a man fleeing Aberdeen, Sierra Leone.

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    Ebola as a Case Study: Lessons Learned

    The Ebola outbreak highlighted the importance of strong public health systems, international cooperation, and rapid response to potential threats.

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    Effective Response to Ebola Requires

    A combination of effective border controls, isolation, contact tracing, and public health education is essential to effectively combat Ebola.

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    Influenza Resistance

    Oseltamivir, a drug for influenza, is becoming less effective due to widespread resistance in the virus.

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    Antigenic Drift

    Small mutations in influenza virus genes that change the virus's surface proteins, making it harder for the immune system to recognize and fight.

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    Antigenic Shift

    When two different influenza viruses swap genes, creating a completely new virus that the immune system has never encountered.

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    Vaccination Effectiveness

    To work effectively, a vaccine needs high uptake, ideally above 95%, to protect the population from outbreaks.

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    Vaccination Programs

    Some vaccination programs are targeted to specific groups, like flu vaccinations for elderly people, to protect those most vulnerable.

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    Geographical Isolation

    Physical barriers, like borders, can help control the spread of diseases, but their effectiveness depends on how strictly they are enforced.

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    Measles Outbreak

    Low vaccination rates can lead to outbreaks of diseases like measles, highlighting the importance of widespread vaccination.

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    Antiviral Therapy

    Treatments using antiviral drugs help combat viral infections, but not all viruses have effective antiviral therapies available.

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    What is a virus?

    A virus is a tiny infectious agent that needs a host cell to replicate. It lacks independent metabolism and cannot regulate its internal environment.

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    What makes viruses different from living organisms?

    Unlike living organisms, viruses cannot grow on their own, reproduce independently, or respond to external stimuli. They are produced fully formed and are not considered alive.

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    What is a viral genome?

    The genetic material of a virus, which can be DNA or RNA, and can be single or double-stranded.

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    What is the structure of a virus?

    A virus typically consists of a protein coat (capsid) surrounding its genetic material. Some viruses also have an outer lipid membrane.

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    How do viruses replicate?

    Viruses enter a host cell and use the host's machinery and energy to replicate their genome and produce new virus particles. They do not have their own metabolism.

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    What is a viral infection?

    When a virus enters a host organism and starts replicating, causing disease.

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    What is a host range?

    The specific type(s) of organisms that a virus can infect. A virus typically has a very limited host range.

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    How do viruses spread?

    Viruses can spread through various routes, including aerosols, fecal-oral transmission, direct contact, blood, and insect bites.

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    What factors influence viral infection?

    Factors like temperature, humidity, sunlight, host-specific factors (genetics, immunity, microbiome, co-morbidities), and the specific tissue type can influence viral infection.

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    How do viruses recognize host cells?

    Viruses often use glycoproteins on their surface to bind to specific receptors on host cell membranes, enabling them to enter cells.

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    What are the steps of viral infection?

    A typical viral infection involves attachment to the host cell, entry, uncoating (removing the capsid), replication of the viral genome, assembly of new virus particles, and release from the host cell.

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    What is viral taxonomy?

    The classification of viruses based on their genetic material, structure, and other characteristics, which helps to understand their relationships.

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    What is Human Cytomegalovirus (HCMV)?

    A common herpesvirus that infects most people, often without symptoms. In immunocompromised individuals, it can cause serious complications.

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    What is a tumor virus?

    A virus that has been linked to an increased risk of cancer development.

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    What is Zika virus?

    A mosquito-borne virus that can cause mild symptoms like fever and rash. It is also linked to birth defects like microcephaly.

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    Study Notes

    Introduction to Microbiology

    • The lecture introduces the role of microorganisms in infectious disease
    • This includes how the organism spreads in a population
    • And how the organism gains access to the host
    • The lecture will cover how to identify the organism causing the disease
    • As well as how to eliminate the organism after infection
    • And how to prevent infection

    History of Medical Microbiology

    • Koch's work on anthrax
    • In the 19th century, Koch studied anthrax
    • Koch determined the disease is caused by rod-shaped gram-positive bacteria
    • Now called Bacillus anthracis
    • Naturally occurring in soil, affects domestic and wild animals
    • Koch collected blood from infected cattle
    • Identified bacterial cells using a microscope
    • Injected infected blood into healthy animals
    • Cultured bacteria from blood
    • Pure cultures of bacteria killed healthy animals
    • Proving bacteria were responsible for anthrax
    • The organism later named Bacillus anthracis
    • Koch's work was published in 1876
    • Confirmed infectious diseases are caused by microorganisms
    • Koch's postulates: criteria for classifying infectious diseases
    • Four conditions must be met
    • Have been slightly altered since, but remain relevant

    Germ Theory of Disease - Koch's Postulates

    • The organism responsible MUST be present in EVERY case
    • The organism MUST be possible to isolate the organism and grow it in a pure culture
    • The isolated organism MUST cause disease in the healthy animal
    • The organism MUST be recoverable from the diseased animal

    Types of Microbes

    • Bacteria
    • Fungi
    • Protozoa
    • Viruses
    • Algae

    Some General Properties of These Organisms

    • Bacteria
    • Prokaryotes
    • Lack organelles
    • No nucleus
    • Protozoa, fungi
    • Eukaryotes
    • contain a nucleus
    • Contain organelles (e.g., mitochondria)
    • Viruses
    • Incapable of independent life
    • Require a host for replication

    Examples of Bacteria Which Can Cause Human Diseases

    • Escherichia coli - found in the digestive tract
    • Neisseria gonorrhoeae - causes gonorrhoea
    • Clostridium tetani - causes tetanus
    • Mycobacterium tuberculosis - causes tuberculosis
    • Borrelia burgdorferi - causes Lyme disease

    Examples of Fungi Relevant to Humans

    • Trichophyton rubrum - involved in athlete's foot
    • Penicillium chrysogenum - source of penicillin
    • Aspergillus nidulans - involved in farmer's lung
    • Saccharomyces cerevisiae - brewing and baking industries

    Examples of Protozoa Associated with Diseases

    • Giardia lamblia - giardiasis (digestive tract infection)
    • Trypanosoma brucei - sleeping sickness
    • Entamoeba histolytica - amoebiasis (digestive tract infection)
    • Trichomonas vaginalis - trichomoniasis (STI)

    Examples of Viruses Associated with Diseases

    • Human Immunodeficiency Virus
    • Ebolavirus
    • Hepatitis Viruses
    • West Nile Virus
    • Corona Virus

    Examples of Algae Associated with Diseases

    • Gambierdiscus toxicus - ciguatera fish poisoning
    • Various - amnesic, paralytic, diarrheal, neurotoxic shellfish poisoning
    • Raphidiopsis raciborskii - Palm Island Mystery disease
    • Alexandrium catenella - Saxitoxin (nerve agent - classed as WMD)

    Microbes in the Body

    • Internal organs are generally free of microorganisms
    • In this context digestive / urinary etc. tracts counts as outside the body
    • Surface tissues have lots of microorganisms
    • Microbiota (microbial community) - called microbiome

    Distribution of human microbiome

    • This slide shows the idea of the microbiome being found in different places
    • Some outside body, others inside
    • Also introduces the idea of different levels of diversity

    Types of microbes

    • Most species of microbe in the human biome are bacteria
    • Colonise from birth onwards
    • Population changes over time

    Types of microbes

    • Early colonisers are commensal bacteria
    • Normally mutualistic / symbiotic relationship with the host
    • Multiple factors influence early colonisers (e.g. Diet, Environmental factors, Geographic location, Use of antibiotics)
    • Access to nutrients
    • Defence mechanisms

    Microbial Adhesion and Attack

    • Healthy skin acts as a reliable barrier to most bacterial attacks
    • However, many microbes will adhere to the surface of the skin
    • Some bacteria attach to surfaces and grow (biofilms)
    • Often involves attachment of bacterial adhesins to the glycoproteins of the skin surface

    External Microbial Flora - Skin

    • However, although bacteria can colonise much of the skin, the distribution is not even
    • Certain areas have more microbes than others.
    • Also, different species in different places

    External Microbial Flora - Skin

    • Factors influencing distribution
    • Nutrients
    • Moisture
    • Temperature
    • pH
    • Skin shedding
    • Fluid osmolarity
    • Potential inhibitors

    External Microbial Flora - Skin

    • Largest numbers of bacteria tend to be found in regions with most apocrine sweat glands

    Microbiology of Skin

    • Two groups of skin-associated microbes (Resident and Transient microbes)
    • Skin in constant contact with environment allowing contact with microbes
    • Transient microbes tend to come in contact with the skin and may attach
    • Conditions are often not favourable for them so they die off
    • Resident population tends to have evolved to preserve their niche for access to nutrients

    Microbiology of Skin

    • Resident population often produce bacteriocins which may kill or help outcompete transient species.

    Transient skin microbes

    • Exposed areas of the body have higher numbers of transients
    • Typically face, neck, hands, etc.
    • Influenced by environmental, domestic and occupational factors

    Internal Microbial Flora

    • The digestive tract, respiratory tract and urogenital tract have direct contact with the outside of the body
    • They also have their own microbial community

    Oral Cavity

    • The oral cavity provides an excellent environment for microbial growth
    • Constant temperature, moist environment, ready supply of nutrients; range of surfaces for attachment
    • Due to food and drink being ingested, there is a risk that the microbes will be washed away
    • Microbes attach to surfaces and also form biofilms
    • Several different attachment sites available: Tongue, Epithelial cells, Teeth, Corners of the mouth / lips, Gums
    • Gingivitis - caused by infections of Streptococcus, Fusobacterium, Actinomyces, Veilonella, Treponema

    Nasal Cavity/Respiratory Tract

    • The nasal cavity also provides favourable conditions for microbial growth
    • Moist conditions, relatively constant temperature, nutritional sources from secretions
    • Microbes enter the nasal cavity during inhalation
    • In more distal areas of the respiratory tract this can also be true, but the mouth provides a point of contact via pharynx

    Stomach

    • The stomach contains VERY acidic conditions (pH 1.5 to 2.0)
    • However, there are still organisms in this region
    • Passed person-person or from food
    • Many probiotic microbes act in the lower gut, but must survive acidic conditions of the stomach
    • Some species preferably live in this environment (such as Helicobacter pylori) - major source of gastric ulcers
    • Once in the stomach, Helicobacter pylori can colonise mucosal surfaces
    • Once attached, Helicobacter pylori can cause inflammation and ulceration

    Small Intestine

    • The microbial community in the small intestine changes due to several variables (Age, Diet, Geographical distribution, Antibiotic exposure, Health, pH)
    • The numbers of microbes in the figure are expressed in terms of numbers per gram of digesta.
    • The genera of organisms include Enterococcus, Bacteroides and Lactobacillus

    Large Intestine

    • The hindgut contains numerous species – very diverse
    • many are obligate anaerobes (oxygen is toxic to them)
    • pH in this area is relatively neutral (4 to 7)
    • The relationship is generally symbiotic (human supplies nutrients, bacteria help to break food down, vitamins)
    • Microbial numbers and composition change with age
    • Links to increased predisposition to diarrhoea in the elderly
    • Diet can impact on the composition and distribution of the microbial community
    • Differences in those eating red meat versus those eating white meat
    • Different probiotics exist, sold to enhance digestive efficiency

    Rectum

    • The rectal bacterial population is very dense due to water being reabsorbed
    • Bacterial population produces several metabolites (Hydrogen sulphide, Methane, Hydrogen, Volatile fatty acids (VFAs))

    Clostridium Difficile Infection

    • C. difficile contains endospores that can survive stomach acidity and reach the large intestine
    • Normal gut flora is altered by broad-spectrum antibiotics
    • C. difficile flourishes within the colon
    • Toxins A & B cause mucosal damage
    • Most common infectious cause of nosocomial diarrhoea

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