Its an antibiotic. It stands for Sulfamethoxazole/Trimethoprim. Also known as co-trimoxazole used in the treatment of bacterial, fungal and protozoan infections.

Co-trimoxazole is a combination of trimethoprim and sulfamethoxazole, a sulfa drug. It is usually useful for the MRSA that is contracted outside of hospitals.

Prolonged treatment with antibiotics, including tetracyclines (with streptomycin), co-trimoxazole, and sulfonamides, is effective. Bed rest is also imperative. In the chronic form of brucellosis, the symptoms may recur, requiring a second.

Usually the drugs used are from the tetracycline class (e.g. tetracycline or doxycycline) or from the fluoroquinolone class (e.g. ciprofloxacin). Co-trimoxazole can be effective in people who cannot take the usual treatment, for example pregnant women.