FMGE 2017 — Microbiology

Q: Which of the following is anaerobic non-acid fast bacilli:

Actinomyces. ***Actinomyces*** - *Actinomyces* species are **obligate anaerobes** to **facultative anaerobes** that appear as **Gram-positive, non-acid-fast, filamentous rods** (bacilli). - They are classically described as **anaerobic bacteria** and are the prototypical example of anaerobic non-acid-fast bacilli. - They cause chronic infections (actinomycosis) often involving abscess formation with sulfur granules and sinus tracts. *Mycobacterium tuberculosis* - *Mycobacterium tuberculosis* is an **obligate aerobe**, not anaerobic. - It is characterized by its **acid-fastness** due to high mycolic acid content in its cell wall. - Requires oxygen for growth and is the causative agent of tuberculosis. *Listeria* - *Listeria monocytogenes* is a **facultative anaerobe**, meaning it preferentially grows in **aerobic conditions** but can survive anaerobically. - While it is a non-acid-fast Gram-positive bacillus, it is **not classified as an anaerobic organism** in standard microbiology terminology. - *Actinomyces* is the classic answer for anaerobic non-acid-fast bacilli. *Nocardia* - *Nocardia* species are **strict aerobes**, not anaerobic. - They are **weakly acid-fast** filamentous bacteria, distinguishing them from the non-acid-fast *Actinomyces*. - Require oxygen for growth and are found in soil. [Practice more Microbiology PYQs on OnCourse]

Q: Vertical transmission of resistance to ciprofloxacin occurs :-

Mutation. ***Mutation*** - Vertical transmission of resistance occurs when a bacterium with a **resistance gene**, such as one conferring resistance to **ciprofloxacin**, replicates and passes that gene to its progeny. - This typically happens through **spontaneous mutations** in the bacterial genome that alter the drug's target or uptake, and these mutations are then inherited by subsequent generations. *Transduction* - **Transduction** involves the transfer of genetic material, including resistance genes, via **bacteriophages** (viruses that infect bacteria). - This is a **horizontal gene transfer** mechanism, not a vertical one. *Conjugation* - **Conjugation** is the direct transfer of genetic material, often in the form of **plasmids**, from one bacterium to another through direct cell-to-cell contact. - This is a form of **horizontal gene transfer**, not vertical transmission. *Transformation* - **Transformation** is the uptake of **free DNA** from the environment by a bacterium, which can then integrate this DNA into its own genome. - This mechanism is also a type of **horizontal gene transfer**, not vertical transmission of resistance to daughter cells during replication. [Practice more Microbiology PYQs on OnCourse]

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Which of the following is anaerobic non-acid fast bacilli:

Vertical transmission of resistance to ciprofloxacin occurs :-

FMGE 2017 - Microbiology FMGE Practice Questions and MCQs

Question 1: Which of the following is anaerobic non-acid fast bacilli:

A. Mycobacterium tuberculosis
B. Listeria
C. Nocardia
D. Actinomyces (Correct Answer)

Explanation: ***Actinomyces*** - *Actinomyces* species are **obligate anaerobes** to **facultative anaerobes** that appear as **Gram-positive, non-acid-fast, filamentous rods** (bacilli). - They are classically described as **anaerobic bacteria** and are the prototypical example of anaerobic non-acid-fast bacilli. - They cause chronic infections (actinomycosis) often involving abscess formation with sulfur granules and sinus tracts. *Mycobacterium tuberculosis* - *Mycobacterium tuberculosis* is an **obligate aerobe**, not anaerobic. - It is characterized by its **acid-fastness** due to high mycolic acid content in its cell wall. - Requires oxygen for growth and is the causative agent of tuberculosis. *Listeria* - *Listeria monocytogenes* is a **facultative anaerobe**, meaning it preferentially grows in **aerobic conditions** but can survive anaerobically. - While it is a non-acid-fast Gram-positive bacillus, it is **not classified as an anaerobic organism** in standard microbiology terminology. - *Actinomyces* is the classic answer for anaerobic non-acid-fast bacilli. *Nocardia* - *Nocardia* species are **strict aerobes**, not anaerobic. - They are **weakly acid-fast** filamentous bacteria, distinguishing them from the non-acid-fast *Actinomyces*. - Require oxygen for growth and are found in soil.

Question 2: Vertical transmission of resistance to ciprofloxacin occurs :-

A. Transduction
B. Mutation (Correct Answer)
C. Conjugation
D. Transformation

Explanation: ***Mutation*** - Vertical transmission of resistance occurs when a bacterium with a **resistance gene**, such as one conferring resistance to **ciprofloxacin**, replicates and passes that gene to its progeny. - This typically happens through **spontaneous mutations** in the bacterial genome that alter the drug's target or uptake, and these mutations are then inherited by subsequent generations. *Transduction* - **Transduction** involves the transfer of genetic material, including resistance genes, via **bacteriophages** (viruses that infect bacteria). - This is a **horizontal gene transfer** mechanism, not a vertical one. *Conjugation* - **Conjugation** is the direct transfer of genetic material, often in the form of **plasmids**, from one bacterium to another through direct cell-to-cell contact. - This is a form of **horizontal gene transfer**, not vertical transmission. *Transformation* - **Transformation** is the uptake of **free DNA** from the environment by a bacterium, which can then integrate this DNA into its own genome. - This mechanism is also a type of **horizontal gene transfer**, not vertical transmission of resistance to daughter cells during replication.