KMU Past Paper Practice

Question:

A 58-year-old man undergoes elective abdominal surgery in which contamination by bowel flora is anticipated. The surgical team selects a cephalosporin with useful activity against selected anaerobic organisms. Which agent best fits this requirement?

Correct Answer: Cefotetan

Explanation: Cefotetan is a cephamycin with useful activity against selected anaerobic organisms, making it relevant when anaerobic coverage is needed.

Question:

A patient is discharged after improvement of a susceptible bacterial infection and is changed from parenteral therapy to an orally administered first-generation cephalosporin. Which drug is most suitable for this route?

Correct Answer: Cephalexin

Explanation: Cephalexin is an orally administered first-generation cephalosporin, whereas cefazolin is an important parenteral representative of the same generation.

Question:

A clinician compares cephalosporin generations while selecting treatment for a gram-negative infection. Which general change best describes progression from first-generation to third-generation agents?

Correct Answer: Increasing activity against gram-negative organisms

Explanation: The broad generational pattern is increasing gram-negative activity from earlier to later cephalosporins; later generations are not simply “stronger” versions of earlier drugs.

Question:

A patient receiving a broad-spectrum cephalosporin develops diarrhea after several days of therapy. No immediate hypersensitivity features are present. Which pharmacological consequence most reasonably contributes to this complication?

Correct Answer: Alteration of normal intestinal flora

Explanation: Broad antibacterial therapy can disturb normal intestinal flora, producing gastrointestinal disturbance and creating conditions for superinfection by resistant organisms.

Question:

A hospitalized patient develops prolonged bleeding while receiving a cephalosporin with a side chain associated with impaired vitamin K-dependent coagulation. Which additional adverse effect is most closely associated with the same group of cephalosporins?

Correct Answer: Alcohol-associated flushing and nausea

Explanation: Certain cephalosporins with characteristic side chains can impair vitamin K-dependent coagulation and also produce a disulfiram-like response after ethanol exposure.

Question:

A patient previously developed an immediate allergic reaction to a penicillin. A cephalosporin is being considered for a new infection. Which property of the drug class is most relevant to this history?

Correct Answer: Potential immunological cross-reactivity with penicillins

Explanation: Penicillins and cephalosporins are beta-lactam antibiotics, and some immunological cross-reactivity can occur; the allergy history is therefore clinically relevant.

Question:

A cephalosporin-sensitive organism is treated with a drug that reaches the site of infection but is cleared so rapidly that its free concentration falls below the MIC for most of the dosing interval. What is the most likely consequence?

Correct Answer: Reduced antibacterial effectiveness

Explanation: Cephalosporin efficacy depends on maintaining free drug concentrations above the MIC for an adequate portion of the dosing interval.

Question:

A patient with severe infection is started empirically on a carbapenem because both aerobic and anaerobic pathogens are possible. Which feature most directly supports this choice?

Correct Answer: Broad aerobic and anaerobic antibacterial activity

Explanation: Carbapenems cover many gram-positive, gram-negative and anaerobic organisms, explaining their role in severe infections where broad coverage is required.

Question:

Culture from a serious infection grows a resistant gram-negative organism. The physician selects a beta-lactam that is relatively stable against many bacterial beta-lactamases and has very broad antibacterial coverage. Which class is being used?

Correct Answer: Carbapenems

Explanation: Carbapenems combine exceptionally broad antibacterial activity with stability against many beta-lactamases, supporting their use in selected serious resistant infections.

Question:

A patient has an infection caused solely by a susceptible aerobic gram-negative bacillus. The physician wants a beta-lactam with a narrow spectrum that avoids unnecessary gram-positive and anaerobic coverage. Which class best fits this strategy?

Correct Answer: Monobactams

Explanation: The monobactam aztreonam provides focused activity against aerobic gram-negative bacteria without useful gram-positive or anaerobic coverage.

Question:

A microbiology report identifies a susceptible anaerobic organism as the major pathogen. Aztreonam is available on the ward. Why would this drug be inappropriate as targeted monotherapy?

Correct Answer: Its activity is limited mainly to aerobic gram-negative bacteria

Explanation: Aztreonam lacks useful activity against anaerobes and gram-positive organisms; its clinically relevant spectrum is aerobic gram-negative bacteria.

Question:

A gram-negative organism is intrinsically poorly susceptible to vancomycin despite having peptidoglycan in its cell wall. Which structural feature best explains the limited activity of vancomycin against this organism?

Correct Answer: Poor penetration through the outer membrane

Explanation: Vancomycin is a large molecule and penetrates the gram-negative outer membrane poorly, explaining why its antibacterial activity is mainly directed toward gram-positive organisms.

Question:

Vancomycin is added to a culture of susceptible gram-positive bacteria. Peptidoglycan precursors accumulate, but normal cell-wall construction fails. Which process has been directly disrupted?

Correct Answer: Incorporation and cross-linking of peptidoglycan

Explanation: By binding D-Ala-D-Ala on peptidoglycan precursors, vancomycin interferes with their incorporation and proper cross-linking during bacterial cell-wall formation.

Question:

A patient receiving intravenous vancomycin for a serious gram-positive infection reports new difficulty hearing. Which recognized toxicity should be considered?

Correct Answer: Ototoxicity

Explanation: Ototoxicity is a recognized adverse effect of vancomycin and should be considered when auditory symptoms develop during therapy.

Question:

A patient develops pain and inflammation along the vein during intravenous vancomycin treatment. There is no generalized flushing or hypotension. Which adverse effect best explains the localized finding?

Correct Answer: Phlebitis

Explanation: Intravenous vancomycin can irritate the vein and produce phlebitis; localized venous pain and inflammation distinguish it from a systemic infusion reaction.

Question:

A microbiologist compares vancomycin with cephalosporins. Both ultimately interfere with bacterial cell-wall formation, but their immediate molecular targets differ. Which statement best distinguishes vancomycin?

Correct Answer: It binds the peptidoglycan precursor rather than a PBP

Explanation: Vancomycin binds D-Ala-D-Ala on the peptidoglycan precursor, whereas cephalosporins exert their beta-lactam effect through penicillin-binding proteins.

Question:

Three cell-wall active drugs are reviewed during ward teaching. One is useful for urinary infection, one is mainly topical because of toxicity, and one is reserved as a second-line antituberculous drug. Which sequence correctly matches these clinical roles?

Correct Answer: Fosfomycin – bacitracin – cycloserine

Explanation: Fosfomycin has an important role in susceptible uncomplicated UTI, bacitracin is mainly topical, and cycloserine is a second-line agent for resistant tuberculosis.

Question:

A researcher compares three non-beta-lactam inhibitors of cell-wall synthesis. One drug prevents transport of peptidoglycan building blocks across the bacterial membrane. Which agent has this action?

Correct Answer: Bacitracin

Explanation: Bacitracin interferes with membrane transport of peptidoglycan precursors, helping explain its inhibition of bacterial cell-wall construction.

Question:

A patient with a susceptible lower urinary tract infection is prescribed a cell-wall active drug that acts before the later steps targeted by beta-lactams. Which stage of bacterial cell-wall formation is principally affected by this drug?

Correct Answer: Early synthesis of peptidoglycan precursors

Explanation: Fosfomycin inhibits an early step of peptidoglycan synthesis, distinguishing its site of action from beta-lactams that interfere with later cell-wall cross-linking.

Question:

A student is asked to match the antibacterial drug with the feature that most strongly determines its clinical role. Which pairing is most accurate?

Correct Answer: Carbapenems — broad coverage for serious complicated infections

Explanation: Carbapenems combine broad gram-positive, gram-negative and anaerobic activity, which explains their important role in selected severe and complicated infections.