One Health Approach to Resistance — MCQs
Which of the following is NOT a core component of the WHO's global STI control strategy?
All are true about ESBL except -
Which of the following is NOT a mechanism of antibiotic resistance?
What is the best way to control the MRSA infection in the ward?
Animal reservoir is seen in all except -
What is the mechanism of resistance in MRSA?
IMCI approach developed by WHO encompasses the following childhood illnesses Except
Which of the following diseases is not covered under the Integrated Disease Surveillance Project (IDSP)?
Which of the following is an example of the transfer of drug resistance by conjugation?
Staphylococcus Oxacillin resistance is best detected by?
One Health Approach to Resistance Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is NOT a core component of the WHO's global STI control strategy?
- A. Case management
- B. Universal mandatory screening (Correct Answer)
- C. Strategic information systems
- D. Prevention services
Explanation: ***Universal mandatory screening*** - While screening is part of STI control, **universal mandatory screening** for all STIs in the general population is not a core component of the WHO's strategy due to feasibility, cost, and ethical considerations. - The strategy emphasizes **targeted screening** for at-risk populations and opportunistic screening. *Case management* - **Case management**, including accurate diagnosis and effective treatment, is a critical component for managing current infections and preventing further transmission. - This involves syndromic or etiologic approaches to treatment and partner notification. *Strategic information systems* - **Strategic information systems** are essential for monitoring trends, evaluating interventions, and informing policy decisions related to STI control. - This includes surveillance data, program monitoring, and research. *Prevention services* - **Prevention services** are a cornerstone of the WHO's strategy, aiming to reduce the incidence of new infections. - These services encompass health education, condom promotion and distribution, vaccination, and pre-exposure prophylaxis (PrEP).
Question 2: All are true about ESBL except -
- A. Resistant to carbapenems (Correct Answer)
- B. Classification is based on 3rd generation cephalosporin sensitivity
- C. Cephalosporin sensitivity testing is required to confirm ESBL
- D. Ambler classification is based on molecular structure
Explanation: ***Resistant to carbapenems*** - **ESBL (Extended-Spectrum Beta-Lactamase)**-producing bacteria are typically **susceptible to carbapenems**. Carbapenems are a primary treatment option for serious ESBL infections. - Resistance to carbapenems suggests the presence of other resistance mechanisms, such as **carbapenemases**, not ESBLs. *Classification is based on 3rd generation cephalosporin sensitivity* - ESBLs are specifically defined by their ability to hydrolyze and confer resistance to **extended-spectrum cephalosporins** (e.g., ceftriaxone, ceftazidime) and aztreonam. - This characteristic resistance to third-generation cephalosporins is key to their definition and clinical identification. *Cephalosporin sensitivity testing is required to confirm ESBL* - **Phenotypic confirmatory tests** for ESBLs involve demonstrating increased resistance to an extended-spectrum cephalosporin alone compared to the same cephalosporin combined with a **beta-lactamase inhibitor** like clavulanic acid. - This testing is crucial for accurate detection and guiding appropriate antibiotic therapy. *Ambler classification is based on molecular structure* - The **Ambler classification system** categorizes beta-lactamases into classes A, B, C, and D based on their **amino acid sequence homology** and their active site mechanisms. - This classification helps in understanding the biochemical properties and substrate profiles of different beta-lactamases, including ESBLs.
Question 3: Which of the following is NOT a mechanism of antibiotic resistance?
- A. Efflux pump activity
- B. Inactivation by enzymes such as beta-lactamase
- C. Modification of drug target sites
- D. Increased drug absorption (Correct Answer)
Explanation: ***Increased drug absorption*** - **Increased drug absorption** would lead to a higher intracellular concentration of the antibiotic, making it *more potent* against the bacteria rather than contributing to resistance. - Antibiotic resistance mechanisms aim to *reduce the effective concentration* of the drug at its target site or *alter the target itself*. *Efflux pump activity* - **Efflux pumps** are bacterial membrane proteins that actively pump antibiotics out of the bacterial cell [3]. - This mechanism *reduces the intracellular concentration* of the antibiotic, preventing it from reaching its therapeutic target [3]. *Inactivation by enzymes such as beta-lactamase* - Bacteria can produce enzymes like **beta-lactamase** that *chemically modify or degrade* the antibiotic molecule, rendering it inactive [2]. - This is a common mechanism of resistance against **beta-lactam antibiotics** (e.g., penicillin, cephalosporins) [2]. *Modification of drug target sites* - Bacteria can develop mutations that *alter the structure of the antibiotic's target site*, such as a bacterial ribosome or cell wall component [1]. - This change in the target means the antibiotic can no longer bind effectively or interfere with cellular processes, thus *losing its efficacy* [1].
Question 4: What is the best way to control the MRSA infection in the ward?
- A. Fumigation of ward frequently
- B. Washing hand before and after attending patients (Correct Answer)
- C. Wearing masks during invasive procedures in ICU
- D. Vancomycin given empirically to all the patients
Explanation: **Washing hand before and after attending patients** - **Hand hygiene** is the single most effective measure in preventing the transmission of **healthcare-associated infections**, including **MRSA**. - **Healthcare workers' hands** are the primary vehicle for spreading pathogens from one patient to another. *Fumigation of ward frequently* - **Fumigation** is generally not recommended for routine infection control and has limited efficacy against resistant organisms like **MRSA** in this context. - It does not address the primary mode of transmission, which is direct contact via **contaminated hands** or surfaces. *Wearing masks during invasive procedures in ICU is important.* - While important for preventing infections during **invasive procedures** and protecting against **aerosolized pathogens**, masks are not the primary strategy for controlling the spread of **MRSA** in routine ward settings. - **MRSA transmission** is predominantly contact-based, not airborne. *Vancomycin given empirically to all the patients* - **Empirical broad-spectrum antibiotic use** for all patients is a significant driver of **antibiotic resistance**, including **MRSA**. - It should be reserved for patients with suspected or confirmed **MRSA infections** based on clinical criteria and culture results, not as a general preventive measure.
Question 5: Animal reservoir is seen in all except -
- A. Yellow fever
- B. Influenza
- C. Rabies
- D. Measles (Correct Answer)
Explanation: ***Measles*** - Measles is a **human-specific disease** and does not have an animal reservoir. - The virus is spread person-to-person through **respiratory droplets**. *Yellow fever* - **Monkeys** are the primary animal reservoir for yellow fever, particularly in jungle cycles. - The virus is transmitted to humans by **mosquitoes** that have fed on infected monkeys. *Influenza* - Various **animal species**, such as birds (especially wild waterfowl) and pigs, serve as reservoirs for influenza viruses. - These animal reservoirs contribute to the emergence of **new human influenza strains** through antigenic shift and drift. *Rabies* - Rabies is a **zoonotic disease** with a significant animal reservoir, predominantly in wild carnivores like raccoons, bats, foxes, and skunks. - Transmission to humans primarily occurs through the bite of an **infected animal**.
Question 6: What is the mechanism of resistance in MRSA?
- A. PBP2a alteration (Correct Answer)
- B. Efflux pump activation
- C. Porins modification
- D. Beta-lactamase production
Explanation: ***PBP2a alteration*** - Methicillin-resistant Staphylococcus aureus (MRSA) acquires the **mecA gene**, which encodes for a modified penicillin-binding protein, **PBP2a**. - **PBP2a** has a low affinity for **beta-lactam antibiotics**, allowing the bacteria to synthesize its cell wall even in the presence of these drugs. *Efflux pump activation* - Efflux pumps are mechanisms used by bacteria to actively pump out various antibiotics from their cells, leading to resistance. - While efflux pumps contribute to resistance against other antibiotics, they are **not the primary mechanism** of methicillin resistance in MRSA. *Porins modification* - Porins are channels in the outer membrane of Gram-negative bacteria that allow the passage of hydrophilic molecules, including some antibiotics. - Modification of porins is a common resistance mechanism in **Gram-negative bacteria** but is not relevant to MRSA, which is Gram-positive. *Beta-lactamase production* - Beta-lactamases are enzymes that **hydrolyze the beta-lactam ring** of antibiotics like penicillin, rendering them inactive. - While many Staphylococcus aureus strains produce beta-lactamase (penicillinase) causing resistance to penicillins, MRSA's resistance to methicillin and other broader-spectrum beta-lactams is primarily due to **PBP2a alteration**, not just beta-lactamase production.
Question 7: IMCI approach developed by WHO encompasses the following childhood illnesses Except
- A. Measles
- B. Malaria
- C. Diarrhoea
- D. Chicken pox (Correct Answer)
Explanation: ***Chicken pox*** - The **Integrated Management of Childhood Illness (IMCI)** strategy focuses on major causes of childhood morbidity and mortality in developing countries. - **Chickenpox** is generally a self-limiting viral illness in otherwise healthy children and is not a primary focus of the IMCI guidelines for acute management. *Measles* - **Measles** is a highly contagious and potentially severe childhood illness that is explicitly covered in the IMCI guidelines. - Due to its high morbidity and mortality rates, especially in malnourished children, IMCI includes guidance on its recognition, classification, and management. *Malaria* - **Malaria** is a leading cause of childhood death in many endemic regions and is a core component of the IMCI strategy. - IMCI provides clear algorithms for the assessment, classification, and treatment of malaria, particularly in children under five. *Diarrhoea* - **Diarrhoea** is one of the most common causes of illness and death in young children, making it a critical disease addressed by the IMCI approach. - IMCI includes detailed protocols for assessing dehydration, classifying the severity of diarrhoea, and guiding treatment.
Question 8: Which of the following diseases is not covered under the Integrated Disease Surveillance Project (IDSP)?
- A. Tuberculosis
- B. Cholera
- C. Herpes zoster (Correct Answer)
- D. Meningococcal disease
Explanation: ***Herpes zoster*** - **Herpes zoster** (shingles) is not included in the Integrated Disease Surveillance Project (IDSP) as it is neither an epidemic-prone disease nor a notifiable disease under the program. - IDSP focuses on diseases with significant public health impact, epidemic potential, or those requiring immediate public health response. - While herpes zoster can cause morbidity in immunocompromised individuals, it does not pose a widespread public health threat requiring national surveillance. *Tuberculosis* - **Tuberculosis (TB)** is explicitly covered under IDSP as a major notifiable disease due to its high burden in India and significant public health importance. - TB surveillance under IDSP helps monitor disease trends, detect outbreaks, and evaluate the effectiveness of the National Tuberculosis Elimination Programme. - Regular reporting and surveillance are essential for achieving TB elimination goals. *Cholera* - **Cholera** is a priority disease under IDSP as an epidemic-prone disease with potential for rapid outbreaks and high mortality if untreated. - It is part of the core surveillance list due to its ability to cause severe dehydration and waterborne epidemics. - Early detection through IDSP enables timely implementation of control measures including safe water supply and oral rehydration therapy. *Meningococcal disease* - **Meningococcal disease** (acute bacterial meningitis) is covered under IDSP due to its high case fatality rate, epidemic potential, and need for urgent public health response. - Surveillance is critical for early outbreak detection and implementation of preventive measures such as mass vaccination and chemoprophylaxis. - Close monitoring helps identify circulating serotypes and guide vaccination strategies.
Question 9: Which of the following is an example of the transfer of drug resistance by conjugation?
- A. Staphylococci to rifampicin
- B. Pneumococcus to penicillin G
- C. M tuberculosis to antitubercular drugs
- D. E coli to streptomycin (Correct Answer)
Explanation: **E coli to streptomycin** - The transfer of **streptomycin resistance** in *E. coli* is a classic example of **conjugation**, mediated by **transferable R-plasmids**. - **Conjugation** involves direct cell-to-cell contact and the transfer of genetic material via a **pilus**, allowing for efficient spread of resistance genes. *Staphylococci to rifampicin* - **Rifampicin resistance** in *Staphylococci* (e.g., MRSA) primarily results from **chromosomal mutations** in the *rpoB* gene, which alters the drug's binding site. - This type of resistance usually arises through **spontaneous mutation and selection**, rather than active transfer via conjugation. *Pneumococcus to penicillin G* - **Penicillin resistance** in *Pneumococcus* (e.g., **PEN-R *S. pneumoniae***) is often due to alterations in **penicillin-binding proteins (PBPs)**, acquired through **transformation**. - Transformation involves the uptake of **naked DNA** from the environment, not direct cell-to-cell contact as in conjugation. *M tuberculosis to antitubercular drugs* - **Drug resistance** in *Mycobacterium tuberculosis* to antitubercular drugs (such as isoniazid and rifampicin) is predominantly mediated by **chromosomal mutations**. - These mutations occur within genes encoding drug targets or drug-activating enzymes, leading to altered drug sensitivity.
Question 10: Staphylococcus Oxacillin resistance is best detected by?
- A. Cefoxitin disc diffusion (Correct Answer)
- B. Oxacillin disc diffusion
- C. Oxacillin agar
- D. Cefoxitin MIC
Explanation: ***Cefoxitin disc diffusion*** - **Cefoxitin** is a **surrogate marker** for oxacillin resistance due to its superior induction of the **mobilized penicillin-binding protein PBP2a**, which mediates methicillin resistance. - The **disc diffusion method** is a cost-effective and widely used technique to determine antibiotic susceptibility by measuring the **zone of inhibition** around an antibiotic-impregnated disc. *Oxacillin disc diffusion* - While oxacillin is the drug in question, **oxacillin disc diffusion** can sometimes miss heterogeneous resistance, leading to **false susceptibility** results. - The detection of resistance with oxacillin can be technically challenging due to the **slow and heterogeneous expression** of resistance genes. *Oxacillin agar* - **Oxacillin agar screening** is a method for detecting methicillin resistance, but **cefoxitin agar** has been shown to be more sensitive and specific for detecting **MRSA**. - This method requires a specific agar medium and incubation conditions, which might be less convenient than disc diffusion for routine testing. *Cefotixin MIC* - **Cefoxitin Minimum Inhibitory Concentration (MIC)** determination is a quantitative method to determine the lowest concentration of an antibiotic that inhibits bacterial growth. - While accurate, **MIC testing** is typically more labor-intensive and costly than disc diffusion, making it less practical for initial resistance screening in many clinical laboratories.
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