Beta-lactam Antibiotics

Which of the following beta-lactam antibiotics is MOST resistant to beta-lactamase degradation due to its bulky acyl side chain?

Which structural feature of cephalosporins confers their superior resistance to beta-lactamases compared to penicillins?

A 52-year-old man with a history of penicillin allergy (non-anaphylactic rash) presents with acute bacterial meningitis. CSF analysis shows elevated protein (180 mg/dL), low glucose (35 mg/dL), and positive Gram stain showing Gram-positive cocci in pairs. Blood cultures are pending. His renal function is normal (creatinine 0.9 mg/dL). Which of the following is the most appropriate antibiotic choice for this patient?

A 32-year-old woman with a history of penicillin allergy presents with a urinary tract infection caused by E. coli. She reports a rash after taking amoxicillin 5 years ago. Before prescribing a beta-lactam antibiotic, which investigation is most appropriate to determine if she can safely receive a cephalosporin?

A 28-year-old male with cystic fibrosis is hospitalized with suspected Pseudomonas aeruginosa lung infection. Sputum culture is pending. The clinician wishes to confirm beta-lactamase production by P. aeruginosa to guide choice between a beta-lactam alone versus a beta-lactam/beta-lactamase inhibitor combination. Which investigation is most appropriate?