Antibiotics: Trimethoprim Sulfamethoxazole

Question 1

What is the mechanism of Trimethoprim Sulfamethoxazole?

Answer 1

Inhibitors of DNA synthesis (sequential inhibition of enzymes required for folinic acid production)

Question 2

What is the spectrum of activity for Trimethoprim Sulfamethoxazole?

Answer 2

• GNB: Enterobacteriaceae, Burkholderia pseudomallei (melioidosis), Salmonella spp.
• Parasites: Toxoplasma gondii (toxoplasmosis)
• Fungal: Pneumocystis jirovecii (PCP)
• GPC: MSSA, MRSA, Nocardia spp

Question 3

What are the indications of Trimethoprim Sulfamethoxazole?

Answer 3

• UTI, prostatitis
• Skin and soft tissue infection
• Misc- PCP, Toxoplasmosis, Nocardia, Melioidosis, Salmonellosis

Question 4

What are the adverse effects of Trimethoprim Sulfamethoxazole?

Answer 4

• GI: nausea, vomiting, diarrhoea, abdominal pain
• Dermatologic: Stevens Johnson syndrome, toxic epidermal necrolysis, erythema multiforme
• Haematologic: bone marrow suppression
• Renal: ↑Cr, ↑K* , ↓Na+
• Hepatic transaminitis