Microbiology

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

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

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

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

The same microbe must be isolated from the diseased animal

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

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

Microorganisms need specific pathways to enter and infect the host.

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

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

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

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

Most bacteria have one chromosome, though exceptions do exist.

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

A type of Salmonella that causes food poisoning.

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

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

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

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

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

A virus that infects bacteria.

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

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

The use of bacteriophages to treat bacterial infections.

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

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

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

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

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

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

The unique biochemical properties of a microorganism used for identification.

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.

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.

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Protozoa that move using hair-like structures called cilia.

Protozoa that move using whip-like structures called flagella.

Trichomoniasis is spread through sexual contact.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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.

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

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

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

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

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

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.

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

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

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

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