Microbial World & Bacterial Basics

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Questions and Answers

Which bacterial component is specifically targeted by penicillin antibiotics?

  • Ribosomes
  • DNA
  • Peptidoglycan (correct)
  • Cell membrane

Which of the following mechanisms enables bacteria to resist macrolide antibiotics?

  • Methylating the 50S ribosomal subunit (correct)
  • Modifying the antibiotic molecule
  • Producing enzymes that degrade the antibiotic
  • Altering the bacterial cell wall to prevent entry

Which of these best describes the function of bacterial ribosomes?

  • Cell motility
  • Protein synthesis (correct)
  • Energy production
  • DNA replication

What role do lipopolysaccharides (LPS) play in Gram-negative bacteria?

<p>Controlling the flow of substances into the cell (D)</p> Signup and view all the answers

Which feature differentiates Gram-positive from Gram-negative bacteria?

<p>A thick peptidoglycan layer (D)</p> Signup and view all the answers

What is the primary purpose of a Gram stain in microbiology?

<p>To classify bacteria based on cell wall composition (C)</p> Signup and view all the answers

Which of these factors increases the risk of infection?

<p>A weakened immune system (C)</p> Signup and view all the answers

How do bacteria acquire antibiotic resistance through horizontal gene transfer involving a pilus?

<p>By direct transfer of genetic material through conjugation (A)</p> Signup and view all the answers

What role does the enzyme beta-lactamase play in antibiotic resistance?

<p>It destroys the structure of beta-lactam antibiotics. (B)</p> Signup and view all the answers

Why are viruses considered obligate intracellular parasites?

<p>They require a host cell for replication. (D)</p> Signup and view all the answers

What is the function of the viral capsid?

<p>To protect the viral genome (C)</p> Signup and view all the answers

How does viral budding contribute to persistent infections?

<p>It allows for slow virus release without killing the host cell. (B)</p> Signup and view all the answers

What is the role of antibodies in adaptive immunity?

<p>To neutralize pathogens and tag them for destruction (B)</p> Signup and view all the answers

What is the primary goal of vaccination?

<p>To prevent future infections by inducing immune memory (B)</p> Signup and view all the answers

How do live attenuated vaccines work?

<p>By introducing a weakened form of the pathogen that replicates slowly (C)</p> Signup and view all the answers

What is the difference between general-purpose and enriched media in culturing bacteria?

<p>Enriched media contain substances to support fastidious bacteria. (A)</p> Signup and view all the answers

A selective and differential medium is used to distinguish bacteria. What properties must it have?

<p>It must inhibit some bacteria while allowing others to grow and show differences. (D)</p> Signup and view all the answers

What is the main advantage of using nucleic acid amplification testing (NAAT) over traditional culture methods?

<p>NAAT provides results within 24 hours. (D)</p> Signup and view all the answers

What is the role of the mucociliary escalator in the respiratory tract's defense?

<p>To move mucus and trapped pathogens away from the lungs (C)</p> Signup and view all the answers

Why are immunosuppressed individuals more susceptible to infections?

<p>Their immune system is weakened. (B)</p> Signup and view all the answers

Which route of transmission involves pathogens that are excreted from the gut of an infected person and enter a new host through ingestion?

<p>Faecal-oral transmission (B)</p> Signup and view all the answers

Which method of transmission requires a vector to carry the pathogen from one host to another?

<p>Vector-borne (C)</p> Signup and view all the answers

In healthcare settings, what is the most common mode of transmission of pathogens?

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

Which of the following is an example of a fomite that can transmit pathogens?

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

Which public health strategy is most effective in reducing the spread of vaccine-preventable diseases?

<p>Routine vaccination programs (A)</p> Signup and view all the answers

What is the primary method for preventing the spread of influenza?

<p>Frequent handwashing and avoiding close contact with infected individuals (B)</p> Signup and view all the answers

How accurate is it to say that the influenza vaccine provides protection against Haemophilus influenzae?

<p>The influenza vaccine does not give any protection against Haemophilus influenzae. (A)</p> Signup and view all the answers

Which vaccination is given to women who are pregnant to protect them and their babies?

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

Normal microbiota in the gut becomes pathogenic when?

<p>They move to a different body site (B)</p> Signup and view all the answers

Cell-based non-culture systems, nucleic acid-based tests and serological tests can be used for which of the organisms?

<p>Difficuly to grow bacteria (D)</p> Signup and view all the answers

Serology can be used for originally tested blood serum but is also good for ?

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

Vaccinations are created by antibodies, B cells, T cells and what other constituent?

<p>Relies on Antigen (A)</p> Signup and view all the answers

What kind of organisms can produce infection

<p>Non-sterile body site flora (C)</p> Signup and view all the answers

Which type of cell causes high risk of infection?

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

Which characteristic is exclusive to Gram-positive bacteria?

<p>A thick peptidoglycan layer (B)</p> Signup and view all the answers

What is the primary function of fimbriae on bacterial cells?

<p>Adhesion to host cells (C)</p> Signup and view all the answers

Why are endospores clinically significant?

<p>They allow bacteria to survive harsh environmental conditions. (C)</p> Signup and view all the answers

Which feature distinguishes a bacterial cell from a virus?

<p>Ability to replicate independently (A)</p> Signup and view all the answers

Which best describes the method by which aminoglycosides inhibit bacterial growth?

<p>Interfering with protein synthesis (D)</p> Signup and view all the answers

How does bacterial conjugation contribute to antibiotic resistance?

<p>Through direct transfer of genetic material, including resistance genes, via a pilus (D)</p> Signup and view all the answers

Why is it important to identify if an isolated microorganism is a potential pathogen or normal flora?

<p>To distinguish between infection and colonization, guiding treatment decisions (C)</p> Signup and view all the answers

What information does the Gram stain provide?

<p>Gram reaction (positive or negative) and cell morphology (A)</p> Signup and view all the answers

In a broth dilution test, how do you interpret the MIC?

<p>The lowest concentration of antibiotic that prevents visible bacterial growth (A)</p> Signup and view all the answers

Which of the mechanisms enables antibiotic resistance by horizontal gene transfer?

<p>Conjugation transferring a plasmid with a resistance gene (B)</p> Signup and view all the answers

What is the primary role of the viral capsid?

<p>Protecting the viral genome (C)</p> Signup and view all the answers

What is the critical factor that dictates the host range of a virus?

<p>The interaction between viral surface proteins and host cell receptors (C)</p> Signup and view all the answers

Which of the following best describes a persistent viral infection?

<p>A long-term infection where virions are continuously released without cell death (C)</p> Signup and view all the answers

During viral replication, what process does the term 'genome copying' describe?

<p>Producing new viral genetic material (C)</p> Signup and view all the answers

How does an inactivated vaccine stimulate an adaptive immune response?

<p>By presenting antigens to the immune system (D)</p> Signup and view all the answers

What feature differentiates inactivated vaccines from live attenuated vaccines?

<p>Cannot replicate in the host (A)</p> Signup and view all the answers

Why are booster doses often required for inactivated vaccines?

<p>To enhance and prolong the immune response (D)</p> Signup and view all the answers

Which method of bacterial identification relies on observing bacterial growth patterns and characteristics?

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

Why is NAAT more advantageous than traditional culture methods?

<p>Provides results more rapidly (A)</p> Signup and view all the answers

A patient presents with a wound infection. The lab performs a Gram stain and reports 'Gram-positive cocci in clusters.' What type of bacteria is most likely?

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

What is a key characteristic of bacteria identified as acid-fast positive?

<p>They retain dye even after acid treatment. (D)</p> Signup and view all the answers

An organism that grows equally well in the presence or absence of oxygen is classified as what type of anaerobe?

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

Which of the following best describes the role of lysozymes in host defense?

<p>Breaking down bacterial cell walls (D)</p> Signup and view all the answers

The dryness and acidity of the skin contribute to host defense primarily by:

<p>Inhibiting pathogen colonization (A)</p> Signup and view all the answers

Which function do macrophages perform in innate immunity?

<p>Engulfing and destroying invading particles through phagocytosis (B)</p> Signup and view all the answers

Exposure to which factor would most directly compromise the effectiveness of the mucociliary escalator in the respiratory tract?

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

Acidity in the stomach functions as a defense mechanism by:

<p>Destroying ingested pathogens (D)</p> Signup and view all the answers

What is the MOST likely mode of disease transmission for influenza?

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

Which situation below illustrates indirect contact transmission?

<p>Touching a contaminated doorknob. (A)</p> Signup and view all the answers

In what way does sanitation reduce the spread of infectious diseases?

<p>By preventing fecal-oral transmission (B)</p> Signup and view all the answers

Which type of transmission is typically associated with Clostridium tetani infections?

<p>Soil-borne transmission (B)</p> Signup and view all the answers

In which scenario is the avoidance of air travel most appropriate?

<p>Avoidance is not a scenario that fits for transmission, instead vaccines area available (C)</p> Signup and view all the answers

What is the rationale of routine vaccination programs?

<p>To eradicate and control infectious diseases through herd immunity (C)</p> Signup and view all the answers

What type of information about vaccination might a pharmacist obtain with the Centers for Disease Control and Prevention (CDC) resource?

<p>Travel-advice (B)</p> Signup and view all the answers

When a patient in his last trimester of pregnancy with influenza asks if he avoid what not eat what is your advice?

<p>They will use vaccine to help with her baby (A)</p> Signup and view all the answers

If for instance a family member needs a Hep A vaxcine who should you not give it do and where does one obtain?

<p>You avoid this on imuno suppressed (C)</p> Signup and view all the answers

After a patient has just had a vaccine what to you suggest at the end of a session?

<p>To keep watch incase for anaphalaxis 15 minutes at a pharmacy (D)</p> Signup and view all the answers

How do bacteria, such as some Gram-negative organisms, prevent drugs like vancomycin from reaching their targets?

<p>By reducing drug entry or actively pumping drugs out to maintain intracellular concentrations. (A)</p> Signup and view all the answers

What is the rationale behind administering a combination vaccine like Tdap?

<p>To simultaneously stimulate immunity against tetanus, diphtheria, and pertussis, offering broad protection. (D)</p> Signup and view all the answers

Which factor primarily determines the likelihood that a microorganism will cause an infection in a host?

<p>The microorganism's ability to cause harm, the number of organisms acquired, and the patient's immune system strength. (C)</p> Signup and view all the answers

A patient is diagnosed with a latent viral infection. Which statement accurately describes this condition?

<p>The viral DNA has integrated into the host's genome but is not actively producing new virions. (B)</p> Signup and view all the answers

A researcher is investigating the mechanism of action of a new antiviral drug. The drug prevents viral entry into cells by blocking the interaction between viral surface proteins and host cell receptors. Which step of the viral life cycle is being targeted?

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

Flashcards

Cell Wall Synthesis Inhibitors

Drugs that target and disrupt cell wall formation in bacteria.

Protein Synthesis Inhibitors

Substances that interfere with protein production in bacteria to inhibit growth.

DNA Inhibitors

Medications that target bacterial DNA to halt replication and cell division.

RNA Inhibitors

Agents that disrupt the formation of RNA, which is essential for protein synthesis.

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Membrane Attackers

Substances that compromise the integrity of the bacterial cell membrane.

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Folate Synthesis Inhibitors

Drugs that block folic acid synthesis, crucial for bacterial growth

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Normal Flora

Harmless microorganisms living in/on the body.

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Pathogenic Bacteria

Microbes causing diseases.

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Bacterial Cell Walls

Prokaryotic cells with peptidoglycan.

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Gram-Positive

Gram-positive bacteria have a thick peptidoglycan layer.

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Identifying Bacteria

Detection via Gram stain.

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Gram-Negative

Outer membrane which contains lipopolysaccharides.

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Bacterial Culture

Artificial environment for bacterial growth.

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Aerobes

Aerobes require oxygen.

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Anaerobes

Anaerobes cannot survive in oxygen.

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Pili

Structures for attachment and gene transfer

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Flagella

Structures providing motility

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Cell Wall

Provides shape and prevents bursting

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Gram Stain

A process used to classify bacteria.

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Minimum Inhibitory Concentration

The lowest concentration of an antibiotic that inhibits bacterial growth

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Disc-Diffusion

A test of antibiotic effectiveness.

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Bacterial Conjugation

Transfer of genetic material between bacteria.

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Obligate Intracellular Parasites

Viruses need host cell to replicate.

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Viral Capsid

Protein shell surrounding a viral genome.

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Virion

Virus + protein coat

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Host - Innate Immune Response

Non-specific defense against pathogens.

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Host - Adaptive Immune Response

Specific defense against pathogens.

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Immunisation

Artificially induces immunity.

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Immunisation - Passive Immunity

Given for temporary protection.

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Immunisation - Active Immunity

Administer non infections version of a pathogen.

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Inactivated Vaccine

Not live Vaccines.

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Live Attenuated Vaccine

Live Vaccines

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Vaccine Hesitancy

Refusal or delay in vaccines.

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Person-to-person transmission

Direct or indirect spread of pathogens from one person.

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Fomites

Indirect transmission via contaminated objects.

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Zoonoses Transmission

Contact w animal/vectors.

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Respiratory droplet.

Direct or indirect spread of pathogens from one person.

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Horizontal Gene Transfer

Antibiotic resistance genes are transferred.

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Altered Permeability / Efflux Pumps

Bacteria increase drug efflux for resistance.

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Study Notes

Microbial world introduction

  • Harmless or beneficial microorganisms reside on and in the body
  • Staphylococci on the skin and Escherichia coli in the gut are examples
  • Some normal flora turn into opportunistic pathogens
  • Can cause disease if they move to different body sites or immunity is low

Bacterial Basics

  • Prokaryotic cells contrast human eukaryotic cells
  • Small, ranging from 1-10 μm
  • Not cells, unlike fungi, yeasts, and viruses

Pathogens

  • Pathogenic Bacteria (Disease-Causing) can be acquired from the environment through inhalation, ingestion, or contact
  • Bacteria can also be aquired from normal flora if bacteria access new body sites or immunity is weak

Factors Affecting Infection Risk

  • Microorganism's ability to cause harm
  • Number of microorganisms acquired
  • Patient's immune system strength

Cell Structures

  • A bacterial cell is prokaryotic and lacks a nucleus.
  • Animal cells are eukaryotic with a nucleus
  • Bacterial cells have a cell wall made of peptidoglycan, which is absent in animal cells
  • Bacterial DNA is a circular chromosome found in the nucleoid region, while animal DNA is linear and enclosed in a nucleus
  • Bacteria lack membrane-bound organelles like mitochondria
  • Bacteria are smaller than animal cells, have smaller ribosomes (70S), and reproduce asexually through binary fission
  • Some bacteria have flagella or pili for movement, while animal cells use cilia or cytoskeleton

Bacteria Cell Wall

  • Plasmids, present in bacteria, are absent in animal cells.
  • Bacteria can have capsules for protection, while animal cells do not
  • Bacteria provide shape, structural support, and resistance to osmotic pressure

Features of Bacteria

  • Not all bacteria have a cell wall
  • Capsules are protective, adhesion and receptor functions.
  • Endospores are dormant forms of bacterium, allowing survival amid adverse conditions
  • Fimbriae are hair-like structures involved for adhesion
  • Flagella are tail(s) enabling motility
  • Inclusion granules store additional material
  • Pilus allows adhesion and translocation of proteins and DNA
  • Plasmids allows a source of genes
  • Outer membrane is part of the cell wall

Gram Positive Bacteria

  • Thick peptidoglycan with alternating repeats
  • Contains teichoic acid and lipoteichoic acid

Gram Negative Bacteria

  • Thin peptidoglycan
  • Additional outer membrane which controls the flow of substances
  • Contains lipopolysaccharides with endotoxins for stabilization and protection

Identifying Microorganisms: Microscopy

  • Stains that visualize
  • Provides quick insight into Gram reaction (positive/negative), cell shape, and arrangement

Identifying Microorganisms: Culture

  • Samples are taken from the affected site and placed in solid or liquid media
  • Grown under ~37°C, varies by pathogen
  • Flora through subculture
  • Bacteria characteristics through microscopy or growth patterns

Antibiotic Susceptibility

  • Determines antibiotics resistant to

Rapid Stage & Microscopy

  • Occurs within hours
  • Cell shape, arrangement, and Gram reaction

Intermediate Result

  • Takes 24-48 hours
  • Involves preliminary identification of the microorganism

Final result

  • Takes several days
  • Provides definitive identification and antibiotic susceptibility

Culture Identification

  • Identify if isolated microorganisms are potential pathogens or normal flora
  • Normal flora are the expected microorganisms at body locations
  • Potential pathogens may induce disease if present
  • Culture provides live sample
  • Culture is limited by growth in artificial media

Cell Arrangement

  • Round spherical (coccus), rod shaped, or curved spirals
  • Bacterial specific arrangements aid the identification
  • Chains divide in one plane
  • Clusters with multiple divide, grapelike
  • Some genera are pairs
  • Four cell groups in square formation

Gram Stain

  • Makes bateria easier to see
  • Classifies bacteria based on cell wall composition
  • Differential stain for cell characteristics

Gram Positive Properties

  • Thick peptidoglycan layer
  • Retains purple stain

Gram Negative Properties

  • Thin peptidoglycan
  • Decolourized by alchohol and stain with pink/red

Atypical Bacteria

  • Does not clearly stain
  • Contains mycoplasmas which lacks a cell wall

Culture of Microbes

  • Grow on artificial nutrient environments Provides nutrients/conditions to specific/select/differentiate growth
  • OBLIGATE aerobes require oxygen at tube tops.
  • OBLIGATE ANAEROBES cannot with oxygen, grow bottom tube.
  • FACULTATIVE ANAEROBES grow tube, oxygen presence
  • AEROTOLERANT anaerobes grow with or without,
  • MICROAEROPHILES require reduced oxygen, middle tube

Media

  • General supports bacteria
  • Enriched contains things that supports bacteria
  • Selective inhibits some to grow
  • Differential is bacteria distinction for identification

Non-Culture Identification

  • Useful for hard to culture

Biochemical

  • Different pathways aid identification Tests run on strips Positive show color

DNA/RNA

  • Bacteria identification
  • PCR tests detect SARS_19 or polymerase test
  • results 24 compared traditional days
  • Can't detect organism susceptibility

Testing Serum

  • based antigens -detect pathogens
  • Antibodies and antigens
  • Multi -well micro plates

Process

  • Coat with antigens for prep
  • Patent Serum with antibody binds
  • Serum bonds with and remotes
  • Chlorogenic enzymes

Results

  • Development on visual
  • Colour light, intensity and concentration

Antimicrobial Agents

  • Inhibits bacterial growth
  • Low drug controls. High ones work

Resistance

  • First of tube with growth on agar
  • Tests Simpler
  • Antibiotic disc plates create cleaning

Results

  • Based on radius of cleaning Suspectible at .06 Resistant is at 2

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