The following antibacterial drug combinations are of accepted benefit in the treatment of the stated infection:

Correct Answer: C

Rationale: Isoniazid, rifampicin, pyrazinamide, and ethambutol (C) is the correct answer as this combination is the standard initial regimen for pulmonary tuberculosis (TB), targeting Mycobacterium tuberculosis. This four-drug therapy, used for the first two months, addresses multiple bacterial targets to prevent resistance and ensure eradication, followed by a continuation phase with isoniazid and rifampicin. Amoxicillin and cefadroxil (A) aren't typically combined for severe urinary tract infections, where broader-spectrum agents like piperacillin-tazobactam are preferred. Phenoxymethylpenicillin and tetracycline (B) are unsuitable for osteomyelitis in children under 5 due to tetracycline's risk of tooth discoloration and lack of synergy. Erythromycin and tetracycline (D) lack evidence as a standard combination for septicaemia, which requires broader coverage. The TB regimen's multi-drug approach is critical given the organism's slow growth and propensity for resistance, making it a cornerstone of global TB management.

Correct Answer: A

Rationale: Hepatitis and cholestatic jaundice (A) are well-documented adverse effects of rifampicin, resulting from its hepatotoxicity, often dose-dependent and reversible, though severe cases require monitoring. Peripheral neuropathy (B) is more associated with isoniazid, not rifampicin. Convulsions (C) aren't typical, though drug interactions via CYP450 induction could indirectly contribute. Influenza-like symptoms (D) occur with intermittent dosing, not daily regimens. Pink/red urine and tears (original E) are harmless discoloration effects, not toxicity. Rifampicin's broad induction of CYP450 enzymes accelerates metabolism of many drugs, necessitating careful management, while its role in TB treatment hinges on RNA polymerase inhibition, making it highly effective but requiring liver function oversight.

Correct Answer: C

Rationale: Fluconazole penetrates the central nervous system well (C), making it ideal for cryptococcal meningitis and other CNS fungal infections, due to its small size and hydrophilicity ensuring high CSF levels. Oral absorption is excellent regardless of food (A is incorrect), with nearly complete bioavailability. Presystemic metabolism is minimal (B is incorrect), unlike voriconazole, enhancing its systemic availability. It's excreted 80% by the kidney (D), requiring dose adjustment in renal failure. It doesn't cause gynecomastia (original E). Fluconazole's efficacy in Candida infections (e.g., thrush, esophagitis) and its favorable pharmacokinetics, including a long half-life, make it a mainstay antifungal, though resistance in non-albicans species is a growing concern.

Correct Answer: C

Rationale: Interferons are indicated in chronic hepatitis C infection (C), with interferon alfa (often pegylated) combined with ribavirin historically, boosting immune clearance of HCV, though direct-acting antivirals now dominate. They're not used in herpes simplex encephalitis (A); aciclovir is standard. They treat chronic hepatitis B (B), suppressing HBV replication. They're indicated in hairy cell leukemia (D), reducing malignant B-cells. They're not used in CMV retinitis (original E). Interferons' antiviral and anticancer effects via immune stimulation and cell cycle inhibition made them vital, though side effects like fatigue and depression often limit tolerability.

Correct Answer: D

Rationale: Cisplatin (D) is considered highly emetogenic, causing severe nausea and vomiting in most patients due to its action on the chemoreceptor trigger zone and GI tract, requiring aggressive antiemetic prophylaxis (e.g., 5HT3 antagonists, dexamethasone). Cyclophosphamide (A) is moderately to highly emetogenic, depending on dose, but less than cisplatin. Methotrexate (B) is mildly emetogenic at standard doses. 5-Fluorouracil (C) causes moderate nausea. Interleukin-2 (original E) is variably emetogenic, not a cytotoxic drug. Cisplatin's alkylating action on DNA is potent against testicular and ovarian cancers, but its emetic potential, linked to serotonin release, makes premedication critical for patient tolerability.