Combination chemotherapy for infections due to methicillin-resistant Staphylococcus aureus with combination therapy by cefuzonam and fosfomycin or minocycline in the urologic field.

To determine the bacterial and clinical effects of methicillin-resistant Staphylococcus aureus (MRSA) on urinary tract infection (UTI), postoperative wound infection, and bacteremia, 22 strains of MRSA from infected patients were examined; minimal inhibitory concentration (MIC), fractional inhibitory concentration (FIC) index, coagulase typing, and change in MIC in the combination of cefuzonam (CZON) and fosfomycin (FOM) or minocycline (MINO), and the clinical effects of the combination therapy of CZON+FOM or CZON+MINO were investigated in 23 patients. MIC distribution was assessed for 11 drugs: methicillin (DMPPC), cefazolin (CEZ), cefotiam (CTM), cefuzonam (CZON), minocycline (MINO), vancomycin (VCM), arbekacin (ABK), imipenem (IPM), fosfomycin (FOM), ofloxacin (OFLX), and clarithromycin (CAM). For VCM and ABK, MICs ranged from 0.2 to 12.5 micrograms/ml. MINO showed a wide range of MIC, from 0.05 to 25 micrograms/ml. All strains were less sensitive to other antimicrobials. This MIC distribution was assessed in categories by coagulase typing. For CAM, type II strains revealed > or = 100 micrograms/ml of MIC50 and MIC90 compared with 0.2 and 3.13 micrograms/ml in type VII strains. For mixed combinations of CZON and MINO at ratios of 10 to 1 and 40 to 1, the rates of blood concentration for drugs 10 and 120 min after the intravenous injection, MIC distribution was observed between MINO and CZON. For mixed combinations of CZON and FOM at ratios of 1 to 1 and 1 to 4, MIC distribution was more sensitive than for FOM or CZON alone. With respect to the clinical effects of combination therapy by CZON+MINO and CZON+FOM, of seven cases of UTI with CZON+MINO, MRSA was eliminated completely in 4 patients (57.1%). In all patients who received CZON+FOM, MRSA was completely eliminated by this treatment regimen. In 4 of 7 (57.1%) patients with would infection and bacteremia, MRSA was eliminated by the combination of CZON+FOM or CZON+MINO. These results suggest that CZON+FOM is an effective combination in treating UTI and other MRSA infections in urology.