7.4. PDF task. Antibacterial drugs that inhibit bacterial cell wall synthesis and increase membrane permeability

1. Classify the drug list into: Penicillins / Cephalosporins / Carbapenems / Monobactams / Beta-lactamase inhibitors / Glycopeptide / Lipopeptides / Polymyxins.

Answer:

Penicillins - Amoxicillin, Penicillin V, Ampicillin, Dicloxacillin, Penicillin G, Ticarcillin, Oxacillin, Nafcillin, Benzathine benzylpenicillin, Procaine Benzylpenicillin.

Cephalosporins - Cefazolin, Cefuroxime, Ceftriaxone, Cefprozil, Cefadroxil, Cefotetan, Cefepime, Cefoperazone.

Carbapenems - Imipenem, Ertapenem, Meropenem. Monobactams - Aztreonam.

Beta-lactamase inhibitors - Clavulanic acid, Sulbactam, Tazobactam.

Glycopeptide - Vancomycin.

Lipopeptides - Daptomycin.

Polymyxins - Colistin Sulfate. All confirmed (pages 8, 18, 22-25). FLAG: Cefprozil not explicitly named in this lecture's list - external but well-established fact.

2. Mechanism of action of beta-lactam antibiotics (A-F): target, binding, result, promotes what, mode of action, which phase and why.

Answer: A) Cell wall/peptidoglycan (murein). B) PBPs (murein transpeptidase). C) Inhibition of transpeptidation. D) Activation of autolysins - leads to autolysis. E) Bactericidal. F) Dividing bacteria - only actively growing bacteria synthesize new cell wall. All confirmed, pages 5 and 7.

3. Which penicillin group is resistant to both gastric acid and penicillinase? List representatives.

Answer: Isoxazolylpenicillins - Oxacillin, Cloxacillin, Dicloxacillin, Nafcillin. Confirmed uniquely correct (pages 8, 12) - the only group with both properties. CORRECTION: these are acid-STABLE (page 12), not "acid labile" as sometimes miswritten.

4. Aminopenicillin properties (underline the correct option in each pair).

Answer: Wide spectrum; Resistant to gastric acid; NOT resistant to penicillinase (page 13); Do NOT affect MRSA; Do NOT affect P. aeruginosa (that's carboxy/ureidopenicillins, page 14); Penetrate CNS/BBB (page 13, though other penicillins need active inflammation per page 15).

5. Antistaphylococcal penicillins: effective against MRSA? Drug for osteomyelitis/endocarditis/bacteremia? Route of isoxazolyl penicillins?

Answer: A) No, not effective against MRSA (page 12). B) Oxacillin, injected IV, for osteomyelitis/endocarditis/bacteremia (page 12). Route: Oxacillin - IV, Dicloxacillin - per os (page 12).

6. 26-year-old woman treated for syphilis, fever, frequent urination, eosinophilia, proteinuria, drug-induced tubulointerstitial nephritis. Which antibiotic? a) Penicillin G b) Cefepime c) Nafcillin d) Aztreonam e) Clavulanic acid

Answer: a) Penicillin G - WITH A FLAG. Penicillin G is the standard syphilis treatment, and interstitial nephritis is a general penicillin-class effect (page 16). However, page 12 specifically names Nafcillin for interstitial nephritis, making c) a real competing answer even though it isn't a syphilis drug. Double-check with your professor.

7. Antipseudomonal penicillins: which drugs, absorption, spectrum, route, which affects clotting, which is ureidopenicillin, which is carboxypenicillin.

Answer: A) Piperacillin, Ticarcillin (page 8, 14). B) Not absorbed orally; wide spectrum, wider with clavulanic acid/tazobactam; given IV (page 14). C) Antipseudomonal penicillins decrease coagulation as a class (page 16) - singling out ticarcillin specifically is a reasonable addition, not stated that way in the lecture. D) Piperacillin = ureidopenicillin (page 8). E) Ticarcillin = carboxypenicillin (page 8).

12. Carbapenem properties (underline the correct option in each pair).

Answer: Wide spectrum; Affect P. aeruginosa (exception: ertapenem does not, page 21); Do NOT affect MRSA; Bactericidal; Well penetrates CNS (conditional on inflamed meninges, page 22, meropenem penetrates best); Given IV. All confirmed, pages 21-22.

8. Benzylpenicillin features (underline the correct option in each pair).

Answer: Cause allergic reactions (pages 9-10); Non-toxic compared to other antibiotics - ties to the therapeutic-index concept from a different lecture, not explicitly restated here; Associated with Jarisch-Herxheimer reaction (pages 10, 16); Potassium or sodium salts (page 8); Active against Treponema pallidum (page 9).

9. Beta-lactamase inhibitor features: spectrum of action, purpose of use, representatives.

Answer: A) No independent spectrum - weak bactericidal action, cannot be used alone (page 23). B) Protect beta-lactams from beta-lactamases; increase spectrum for aminopenicillins, carboxypenicillins, ureidopenicillins (page 23). C) Clavulanic acid, tazobactam, sulbactam (page 23).

10. On what basis are cephalosporins classified into generations?

Answer: Earlier generations - Gram+ coverage; later generations - increasing Gram- coverage and beta-lactamase resistance; P. aeruginosa coverage appears from gen III; gen V targets MRSA. Matches pages 17-20.

11. Match cephalosporins to their generation: Cefuroxime, Cefadroxil, Cefotetan, Cefepime, Ceftriaxone, Cefprozil.

Answer: Cefuroxime = II, Cefadroxil = I, Cefotetan = II, Cefepime = IV, Ceftriaxone = III, Cefprozil = II. All confirmed (page 18) except Cefprozil, which isn't explicitly named in this lecture (external but well-established fact).

13. Cephalosporin characteristic features (underline the correct option in each pair).

Answer: NOT resistant to cephalosporinases (page 17 - resistant to penicillinase, but susceptible to cephalosporinases); III-IV generations penetrate CNS (pages 19-20, cefuroxime is a II-gen exception); Bactericidal; Only II-V generations have broad spectrum (page 17 - note the quiz option only offers "II-IV," slightly incomplete vs the source, which says II-V); III-IV generations active against P. aeruginosa (pages 19-20); V generation active against MRSA (pages 17, 20).

14. Cephalosporin-specific properties: bile-excreted/safe in renal insufficiency, disulfiram-like reaction, inhibits clotting, mechanism, which property causes these reactions.

Answer: A) Cefoperazone, Ceftriaxone - bile excreted (page 19). B) Disulfiram-like reaction - Cefotetan AND Cefoperazone (page 21, not just Cefotetan). C) Inhibit clotting - Cefotetan, Cefoperazone (page 21). Mechanism: N-methylthiotetrazole side chain (pages 19, 21); the Vitamin-K-dependent clotting factor detail is a correct addition from general pharmacology, not spelled out verbatim in this lecture.

15. Carbapenem metabolism fill-in: which carbapenem forms a nephrotoxic metabolite, via which enzyme, protective agent, which carbapenem is unmetabolized and used for what.

Answer: A) Imipenem, metabolized by dehydropeptidase, forms a nephrotoxic metabolite (page 22). B) Cilastatin (page 22). C) Meropenem, not metabolized, used for meningitis (page 22).

16. 7-year-old with cystic fibrosis, recurrent pneumonia, green sputum, P. aeruginosa. Which antibiotic? a) Piperacillin b) Cefotetan c) Amoxicillin d) Clavulanic acid e) Oxacillin f) Penicillin G

Answer: a) Piperacillin - the only antipseudomonal option (page 8, 14). None of the others have Gram-negative/pseudomonal coverage.

17. Comparison of vancomycin and daptomycin: mechanism, spectrum, metabolism, mode of action, clinical applications.

Answer: Vancomycin - binds D-Ala-D-Ala, inhibits transglycosylation; narrow Gram+ only; not metabolized, eliminated unchanged in urine; bactericidal (dividing bacteria only); used for MRSA, penicillin-resistant strep, C. difficile, endoprosthetic surgery. Daptomycin - depolarizes cytoplasmic membrane + inhibits DNA/RNA/protein synthesis; narrow Gram+ (MSSA/MRSA, VRE, penicillin-resistant strep, E. faecalis/faecium); not metabolized, eliminated unchanged; bactericidal (dividing and resting bacteria); used for complicated skin/soft tissue infections, bacteremia, endocarditis. All confirmed, pages 24-25.

18. Match drug from list to characteristic: narrow spectrum + active against P. aeruginosa; no cross-allergic reaction with beta-lactams; acts bactericidally. (Ampicillin, aztreonam, cefepime, cefotaxime, cefotetan, ceftazidime, ceftriaxone, ticarcillin, piperacillin, vancomycin)

Answer: A) Aztreonam - narrow spectrum + active against P. aeruginosa (page 23). B) Aztreonam - no cross-allergic reaction with other beta-lactams (page 23). C) Acts bactericidally - AMBIGUOUS in the source material: virtually every drug in this list is bactericidal per page 4, so "all but aztreonam" doesn't clearly follow from the lecture. Double-check this sub-answer with your professor.

19. 4-year-old, recurrent pulmonary infections, Gram-positive cocci in grape-like clusters. Treatment? a) Penicillin G b) Ampicillin c) Piperacillin d) Dicloxacillin

Answer: d) Dicloxacillin. Grape-like clusters = Staphylococcus. Penicillin G is ineffective against penicillinase-producing staph (page 9); dicloxacillin is the penicillinase-resistant option (page 12).

20. 54-year-old, Candida vaginitis after amoxicillin for a skin infection. Cause? a) Excessive immune response b) Resistant viruses c) Skin infection progression d) Disrupted microbiota balance e) Stevens-Johnson syndrome

Answer: d) Disrupted microbiota balance. Matches the general concept of amoxicillin-induced dysbacteriosis/superinfection (page 14).

21. 31-year-old, tonsillitis, amoxicillin. Molecular mechanism? a) Activation of bacterial autolysin synthesis b) Binding to 30S ribosome c) Activation of efflux pumps d) Inhibition of transglycosylase e) Inhibition of DNA-dependent RNA polymerase

Answer: a) Activation of bacterial autolysin synthesis. Page 7 explicitly describes this as part of beta-lactams' killing mechanism. FLAG: option d ("transglycosylase") is a distractor describing vancomycin's mechanism (page 24), not amoxicillin's - beta-lactams target transpeptidase (pages 5, 7), a different enzyme.

22. 74-year-old, P. aeruginosa pneumonia, prior severe ampicillin allergy, needs a beta-lactamase-resistant beta-lactam active against this pathogen. Which one? a) Imipenem b) Ceftazidime c) Amoxicillin d) Aztreonam e) Cefepime

Answer: d) Aztreonam. Explicitly the only option noted for zero cross-sensitivity with penicillins, active against P. aeruginosa, and resistant to beta-lactamases (page 23) - matches every criterion in the vignette.

23. 11-year-old, MRSA, treated with vancomycin. Which endogenous process is inhibited? a) Elongation of the peptidoglycan chain b) Unwinding of DNA double helix c) Binding to 50S ribosome d) Translocation of tRNA e) Activation of autolysins

Answer: a) Elongation of the peptidoglycan chain. Vancomycin inhibits transglycosylation, the chain-elongation step of peptidoglycan synthesis (pages 5, 24).

24. 42-year-old, MRSA endocarditis, hypotension/tachycardia/pruritus/flushing 15 minutes after IV infusion. Which antibiotic? a) Imipenem b) Vancomycin c) Cefazolin d) Oxacillin e) Ampicillin f) Cefepime

Answer: b) Vancomycin. Classic Red Man Syndrome from rapid infusion, caused by histamine release (page 24).

25. 75-year-old, elective hip replacement. Prophylactic drug? a) Penicillin G b) Aztreonam c) Vancomycin d) Cefazolin e) Cefepime f) Colistin

Answer: d) Cefazolin. Explicitly named for surgical prophylaxis (page 18).

26. Polymyxins: mechanism of action, mode of action, which phase of cells they act on, adverse effects.

Answer: Mechanism - act on the phospholipid component of the bacterial membrane, disrupting its integrity so cytoplasmic contents leak out. Mode: Bactericidal. Act on both growing and resting bacteria. Adverse effects: Nephrotoxicity, Neurotoxicity. All directly from page 25.