Microbiology Quiz on Infections and Pathogens
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Questions and Answers

Which fungal genus is characterized by banana-shaped or canoe-shaped conidia?

  • Fusarium (correct)
  • Penicillium
  • Aspergillus
  • Alternaria

What mycotoxin is primarily produced by Aspergillus and Penicillium?

  • Ochratoxin A (correct)
  • Patulin
  • Aflatoxin
  • Zearalenone

In HIV-1, where does reverse transcription of the viral genome primarily occur?

  • In the cytoplasm
  • In the nucleus
  • In the virion (correct)
  • In the endoplasmic reticulum

What is the correct classification group for retroviruses under the Baltimore classification system?

<p>Group 6 (C)</p> Signup and view all the answers

What is a common method for diagnosing Schistosomiasis?

<p>Observation of eggs in stool samples (D)</p> Signup and view all the answers

What type of genome does HIV-1 possess?

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

Which of the following statements about Schistosomiasis detection is correct?

<p>Eggs can be found in stool or urine samples (D)</p> Signup and view all the answers

What role does the HIV-1 spike protein play in the virus?

<p>It helps the virus attach to host cells (C)</p> Signup and view all the answers

Which option correctly describes endogenous infections?

<p>They are caused by normal microflora. (B)</p> Signup and view all the answers

What is the primary reason pathogenic bacteria attach to host cells?

<p>To obtain nutrients. (B)</p> Signup and view all the answers

How does Listeria monocytogenes evade phagocytosis?

<p>By escaping the phagosome to survive in the cytoplasm. (A)</p> Signup and view all the answers

Which type of microscope is essential for visualizing a phage particle?

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

What is the differential agent used in TCBS medium?

<p>Sucrose fermentation. (D)</p> Signup and view all the answers

What technique involves inoculating a liquid sample into sterile aerobic and anaerobic bottles?

<p>Blood culture sampling. (B)</p> Signup and view all the answers

Which characteristic is NOT associated with opportunistic pathogens like normal microflora?

<p>They originate from external sources. (D)</p> Signup and view all the answers

What is a key function of bacterial capsules in evading the immune response?

<p>Preventing phagocytosis. (D)</p> Signup and view all the answers

Which stage of the malaria parasite is primarily responsible for causing clinical manifestations of the disease?

<p>The blood stages or sporozoites (A)</p> Signup and view all the answers

What is the fundamental purpose of the BLAST tool in bioinformatics?

<p>To compare biological sequence information (A)</p> Signup and view all the answers

Which of the following challenges does not arise when culturing and identifying pathogenic bacteria?

<p>High pathogen loads facilitating easy isolation (A)</p> Signup and view all the answers

What is the likely result of a polymicrobial infection involving microorganisms such as Pseudomonas aeruginosa?

<p>Increased difficulty in isolating specific pathogens (B)</p> Signup and view all the answers

Why is it important to correctly culture and identify pathogenic bacteria from an infection site?

<p>To improve diagnostic accuracy and treatment (A)</p> Signup and view all the answers

Which type of bacteria is known to require anaerobic conditions for culturing?

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

What role do commensal bacteria, such as Staphylococcus epidermidis, play in the challenge of culturing pathogenic bacteria?

<p>They complicate the isolation process (A)</p> Signup and view all the answers

Which of the following statements about the identification of pathogens is false?

<p>Low pathogen loads make culturing straightforward. (D)</p> Signup and view all the answers

Which fungal pathogen is known to cause cryptococcal meningitis?

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

Which of the following is a well-known dermatophyte fungus?

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

Consumption of which commodity is most commonly associated with aflatoxicosis?

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

What does the term 'estrogenic' refer to?

<p>It causes alterations in the reproductive tract (C)</p> Signup and view all the answers

Which statement about mycotoxins is accurate according to the IARC?

<p>Only aflatoxin B1 is classified as carcinogenic (C)</p> Signup and view all the answers

Fumonisins are produced primarily by which genera?

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

What is a common challenge when culturing slow-growing bacteria like Mycobacterium tuberculosis?

<p>They have very specific nutrient requirements. (A)</p> Signup and view all the answers

Which of these fungi is associated with infection of skin, hair, and nails?

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

Which of the following mycotoxins is known to be a carcinogen?

<p>Aflatoxin B1 (C)</p> Signup and view all the answers

Which method can be used to enhance the success rate of culturing blood samples with low pathogen numbers?

<p>Concentrating samples. (A)</p> Signup and view all the answers

How does the use of BACTEC systems improve the culturing process?

<p>By automating the detection of microbial growth. (A)</p> Signup and view all the answers

Why is it important to combine traditional culture methods with molecular techniques?

<p>To achieve rapid and accurate detection of pathogens. (D)</p> Signup and view all the answers

What is the role of selective media when dealing with polymicrobial infections?

<p>To differentiate pathogens from commensal bacteria. (B)</p> Signup and view all the answers

Which of the following is least likely to result in a Healthcare-associated Infection (HCAI)?

<p>Food poisoning that requires a hospital admission (C)</p> Signup and view all the answers

Which of the following bacteria primarily requires enriched media that contains specific nutrients?

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

What is the primary purpose of a blood culture sampling?

<p>To detect microorganisms in the bloodstream (D)</p> Signup and view all the answers

What technique is recommended to disrupt biofilms before attempting to culture bacteria from them?

<p>Mechanical or enzymatic disruption. (A)</p> Signup and view all the answers

Which microorganism is associated with causing deep-seated infections in humans?

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

What does PCR primarily provide in the context of bacterial culturing?

<p>Quick results for identifying and quantifying pathogens. (C)</p> Signup and view all the answers

In calculating the final API 20E code, what is the score for Group 6 comprised of tests RHA, SAC, and MEL?

<p>0 (A)</p> Signup and view all the answers

Which of the following is an incorrect statement about the scoring for the API 20E strip tests?

<p>Each test is scored as 0, 1, 2, or 4. (D)</p> Signup and view all the answers

What is the scoring contribution of a negative result in any group of the API 20E tests?

<p>0 (D)</p> Signup and view all the answers

During which condition is a Chloridoids difficile infection most likely to occur?

<p>After long-term hospitalization with antibiotics (A)</p> Signup and view all the answers

What does the final API 20E code of 5-1-4-7-3-0-2 indicate?

<p>It represents a specific biochemical profile of a microorganism. (B)</p> Signup and view all the answers

Flashcards

Endogenous Infection

An infection caused by microorganisms that are normally present in the body's own microflora, but become pathogenic under certain conditions.

Bacterial Attachment to Host Cells

The process by which pathogenic bacteria attach to host cells, providing access to nutrients and helping them resist being flushed out of the body.

Listeria monocytogenes Evasion Mechanism

A bacterial pathogen that escapes from a phagosome into the cytoplasm of a phagocytic cell, allowing it to replicate and evade the host's immune defenses.

Transmission Electron Microscope

A type of microscope that uses a beam of electrons to illuminate a sample, providing high resolution and allowing visualization of small structures like phage particles.

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TCBS Medium

A selective medium that differentiates Vibrio species based on their ability to ferment sucrose.

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Blood Culture Sampling

A laboratory technique used to detect microorganisms in liquid samples like blood, by monitoring the turbidity of a growth medium.

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Inhibition of Phagosome-Lysosome Fusion

A process by which bacteria evade phagocytosis by inhibiting the fusion of phagosomes with lysosomes, preventing the destruction of bacteria within phagocytes.

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Evasion of Immune Defenses

The ability of a microorganism to avoid being targeted and destroyed by the host's immune system.

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What are Healthcare-associated infections (HCAIs)?

Healthcare-associated infections (HCAIs) are infections acquired during a hospital stay or healthcare intervention, not pre-existing conditions contracted outside the hospital.

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What is blood culture sampling used for?

Blood culture sampling is a laboratory test used to detect microorganisms (like bacteria or fungi) in the bloodstream.

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What is the API 20E strip?

The API 20E strip is a biochemical test used to identify different types of bacteria based on their ability to use or produce specific substances.

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How do you calculate the code for the API 20E strip?

A positive test on the API 20E strip is scored as 1, 2, or 4, depending on the specific test group. The scores for each group are then combined to create a final code that identifies the bacterial species.

For example, if the first three tests in a group are positive (+), negative (-), and positive (+), you'd score them as 1 + 0 + 4 = 5.

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Which of the following causes deep seated infections in humans?

Filobasidiella neoformans is a type of fungus that can cause serious infections, especially in people with weakened immune systems.

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What is LJ slope sampling?

LJ slope sampling is a technique used for growing and isolating microorganisms from patient samples, such as sputum or other body fluids.

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What is the API 20E strip?

The API 20E strip is a biochemical test used to identify different types of bacteria based on their ability to use or produce specific substances.

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How do you calculate the code for the API 20E strip?

A positive test on the API 20E strip is scored as 1, 2, or 4, depending on the specific test group. The scores for each group are then combined to create a final code that identifies the bacterial species.

For example, if the first three tests in a group are positive (+), negative (-), and positive (+), you'd score them as 1 + 0 + 4 = 5.

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Culture of Pathogenic Bacteria

A technique used to identify and study microorganisms by growing them in a controlled environment.

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Identification of Pathogenic Bacteria

A laboratory technique used to identify the specific type of microorganism present in a sample by analyzing its characteristics, often including growth patterns and biochemical reactions.

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Polymicrobial Infection

An infection involving two or more different types of microorganisms, which makes isolating individual pathogens more challenging.

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Fastidious Bacteria

A type of bacteria that requires specific and often complex growth conditions to thrive.

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Anaerobic Bacteria

A type of bacteria that can only grow in the absence of oxygen.

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Low Pathogen Load

A situation where the number of bacteria in a sample is very low, making it difficult to isolate and identify them.

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Commensals

Bacteria that are normally found in the body but can sometimes become harmful, making it difficult to distinguish them from true pathogens.

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BLAST

A bioinformatics tool used to compare biological sequences like DNA, helping researchers identify similarities and relationships between different organisms.

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Aspergillus

A fungal genus known to produce mycotoxins, including aflatoxins, which can contaminate food and pose health risks.

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Fusarium

A fungal genus primarily responsible for producing fumonisins, a group of mycotoxins that can cause various health issues.

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Aflatoxin B1

A type of mycotoxin produced by certain fungal species, primarily Aspergillus, known for its potential to cause liver cancer and other health problems.

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Fumonisins

A type of mycotoxin produced by Fusarium species, known to cause various health issues including esophageal cancer.

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Dermatophytes

A group of fungi that infect keratinized tissues like skin, hair, and nails, causing various dermatological infections.

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Deoxynivalenol (DON)

A type of mycotoxin produced by Fusarium species, associated with various health problems including digestive issues, kidney damage, and immune suppression.

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Filobasidiella neoformans

A fungal species that is the teleomorph (sexual form) of Cryptococcus neoformans, a pathogen causing serious infections like cryptococcal meningitis.

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Trichophyton interdigitale

A fungal species that causes infections of the skin, hair, and nails, known to be a common cause of athlete's foot and other dermatophytosis.

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What is Ochratoxin A?

A mycotoxin primarily produced by species of Aspergillus and Penicillium.

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What is reverse transcription?

The process by which a virus's RNA genome is converted into DNA using the enzyme reverse transcriptase.

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What is the Baltimore Classification system?

A viral classification system that groups viruses based on their genome, replication strategy, and other characteristics.

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How is Schistosomiasis typically diagnosed?

The presence of Schistosoma eggs in stool or urine samples is a common diagnostic method.

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What is the importance of bacterial evasion mechanisms?

The ability of bacteria to evade the host's immune defenses by avoiding phagocytosis, lysosomal destruction, or other immune responses.

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How do bacteria attach to host cells?

The process by which bacteria attach to host cells, providing access to nutrients and resisting being flushed out of the body.

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Why do pathogens have evasion mechanisms?

The ability of a microorganism to avoid being recognized and eliminated by the host's immune system.

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Which genus is not a fungus?

This genus of bacteria includes Escherichia coli, a commonly found bacterium in the human gut.

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Low pathogen numbers

Very low numbers of bacteria in the sample, making them difficult to culture.

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Differentiating contaminants/commensals

Distinguishing real disease-causing bacteria from harmless ones that naturally occur in the body.

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Slow-growing bacteria

Bacteria that grow very slowly, taking a long time to form visible colonies.

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Biofilms

Groups of bacteria encased in a protective film, making them resistant to antibiotics and difficult to culture.

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Using PCR for quick results

Using PCR (polymerase chain reaction) to rapidly detect specific bacterial DNA in samples.

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Study Notes

Endogenous Infections

  • Endogenous infections are caused by microorganisms already present in or on the body.
  • These microorganisms are often part of the normal microflora.
  • Under certain conditions, these normal microflora can become opportunistic pathogens.

Pathogenic Bacteria Attachment

  • Pathogenic bacteria attach to host cells to avoid antibodies.
  • Attachment allows access to nutrients and helps bacteria colonize the host.
  • Attachment also helps bacteria resist being flushed from the body.

Listeria monocytogenes Phagocytosis

  • Listeria monocytogenes escapes phagocytosis by escaping the phagosome and surviving inside the phagocytic cell.
  • It does this by surviving at low pH after phagosome-lysosome fusion.
  • This escape allows the bacterium to replicate and evade the host's immune system.

Visualizing Phage Particle

  • Transmission electron microscopy is used to visualize phage particles.
  • This is because transmission electron microscopy provides the resolution needed to see the small size of phage particles.

Differential Agent in TCBS Medium

  • Sucrose fermentation is a differential agent in TCBS (Thiosulfate Citrate Bile Salts Sucrose) medium.
  • This is used to differentiate Vibrio species.

Analysis Technique for Patient Samples

  • Blood culture analysis involves inoculating a liquid sample into sterile bottles in a liquid growth medium.
  • Then, turbidity is monitored to identify microorganisms.
  • This method is used to detect microorganisms in the bloodstream.

Healthcare-Associated Infections (HCAIs)

  • HCAIs are infections acquired during a hospital stay or healthcare procedures.
  • Not pre-existing conditions, like food poisoning acquired outside the hospital.

API 20E Code Calculation

  • Each test is scored as 1, 2, or 4 based on its positivity or negativity.
  • Combining the scores for the first three tests in each group determines the group's score.
  • Repeating this process for all seven groups provides the final code.

Deep-Seated Infections in Humans

  • Filobasidiella neoformans (a fungal pathogen) causes deep-seated infections like cryptococcal meningitis.

Dermatophyte Fungi

  • Trichophyton interdigitale is a type of dermatophyte fungus.
  • Dermatophytes infect keratinized tissues, including skin, hair, and nails.

Aflatoxicosis

  • Aflatoxins (produced by Aspergillus species) are associated with improperly stored grains like wheat, corn, and peanuts.
  • Consumption of these contaminated grains can cause aflatoxicosis.

Estrogenic Meaning

  • Estrogenic refers to the capability to damage or cause alterations in the reproductive tract.
  • This can include damaging the reproductive tract.
  • Estrogenic compounds often mimic or disrupt estrogen activity leading to changes in the reproductive system.

Carcinogenic Mycotoxins

  • Aflatoxin B1 is classified as a Group 1 carcinogen (by the IARC).
  • This means it's known to cause cancer in humans.

Fumonisins Production

  • Fumonisins are primarily produced by Fusarium species.
  • Aspergillus species can also produce fumonisins to a lesser extent.

Ochratoxin A Production

  • Aspergillus and Penicillium species are the primary producers of ochratoxin A.

HIV-1 Characteristics

  • HIV-1's reverse transcriptase is carried within the virion.

Baltimore Classification System

  • Viruses are classified by the structure of their genome (e.g. DNA or RNA) in the Baltimore Classification System.
  • Retroviruses are in group 6.

Schistosomiasis Detection

  • Observing eggs in stool samples is a common method to detect Schistosomiasis.

Malaria Life Cycle

  • Targeting the blood stages or sporozoites prevents malaria.
  • These stages are crucial for stopping symptoms and clinical manifestations of malaria.

BLAST (Basic Local Alignment Search Tool)

  • BLAST is a bioinformatics tool that compares biological sequences like DNA or protein sequences.
  • It finds similarities in sequences; and thus helps determine how similar two sequences are.

Pathogenic Bacteria Culture Challenges

  • Polymicrobial infections (multiple bacteria in one sample) are common, making isolate identification difficult.
  • Fastidious bacteria, those requiring specific nutrients, prove challenging.
  • Anaerobic bacteria (those not requiring oxygen) also present a hurdle.
  • Low numbers of pathogens, and the presence of commensal microbes (e.g., S. epidermidis) can complicate isolation.
  • Slow-growing bacteria and biofilm-forming pathogens add complexities.

Overcoming Culture Challenges

  • Using polymerase chain reaction (PCR) for faster results
  • Automating processes (like use of BACTEC for blood cultures).
  • Integrating traditional methods with modern techniques improves efficacy.

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Description

Test your knowledge on endogenous infections, pathogenic bacteria attachment, and Listeria monocytogenes' ability to escape phagocytosis. Additionally, learn about the techniques used to visualize phage particles. This quiz covers essential concepts in microbiology relevant to pathogens and host interactions.

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