Susceptibility of urine isolates of Staphylococcus saprophyticus to antimicrobial agents

The minimum inhibitory concentrations (MICs) of 10 antimicrobial agents for 96 urinary isolates of Staphylococcus saprophyticus cultured from symptomatic females in the Western Australian general community are reported. All antimicrobial agents tested showed good activity, with the exceptions of norfloxacin (MIC90 8 mg/L) and ampicillin (MIC90 0.5 mg/L). Eighty-three of 96 isolates were susceptible to all antimicrobial agents tested. One isolate was resistant to both tetracycline and trimethoprim. The remainder were resistant to a single antimicrobial agent; 10 to tetracycline and 2 to trimethoprim. None of the isolates exhibited any detectable beta-lactamase activity when tested by the chromogenic cephalosporin method. Synergy between trimethoprim and sulphafurazole against Staph. saprophyticus was demonstrated in only 2 of 5 strains having an increased MIC of one or both of these agents.