Comparative studies on activities of antimicrobial agents against causative organisms isolated from urinary tract infections (1986). III. Secular changes in susceptibility

: Changes in the susceptibility of various infectious microorganisms to antimicrobial agents from 1982 to 1986 were evaluated. The microorganisms investigated were Escherichia coli, Klebsiella spp., Citrobacter spp., Enterobacter spp., Proteus spp., Serratia marcescens and Pseudomonas aeruginosa isolated from patients with urinary tract infections. We compared susceptibilities of microorganisms obtained from simple urinary tract infections with those from complicated infections with or without indwelling catheter. Among penicillins, mecillinam (MPC) showed the strongest activity against E. coli obtained from the patients: 3.13 to 6.25 micrograms/ml of MPC inhibited the growth of over 90% of the isolates. Among the second and the third generation cephalosporins, cefotiam and cefmenoxime (CMX) showed the strongest activity and the growth of isolates was inhibited at concentrations of 0.39 to 0.78 microgram/ml and below 0.10 to 0.20 microgram/ml, respectively. The activities of penicillins against Klebsiella spp. were weak. CMX showed strong activity against Klebsiella spp; 91.7% of the isolates from patients with simple infections were inhibited at 0.39 microgram/ml of the agent; 90.7% and 91.6% of isolates from patients with complicated infections with or without indwelling catheter were inhibited at 0.78 microgram/ml and 1.56 microgram/ml of the agent, respectively. Gentamicin (GM) also showed strong activity against isolates from patients with simple infections and weaker activity against isolates from patients with complicated infections with the catheter; 0.78 microgram/ml of ofloxacin (OFLX) inhibited the growths of 90% of the isolates from these patients. Penicillins showed weak activity against Citrobacter spp. obtained from the patients. Among the second and the third generation cephalosporins, CMX and latamoxef (LMOX) showed strong activities against the Citrobacter isolates; about 50% of the isolates were inhibited at 0.20 microgram/ml of either agent. 1.56 microgram/ml of minocycline inhibited the growth of 75 to 90% of the isolates and 1.56 microgram/ml of OFLX inhibited the growth of 93 to 100% of the isolates. Against isolates of Proteus spp. penicillins also showed weak activities. Among them, however, piperacillin (PIPC) inhibited the growth of over 90% of the isolates at concentrations ranging from 0.78 to 1.56 micrograms/ml. Among the second and third generation cephalosporins, CMX and LMOX showed strong activities; 0.20 microgram/ml of CMX inhibited the growth of 94.4%, 90.4%, and 83.1% of isolates from the 3 types of the patients, respectively. 0.20 microgram/ml of LMOX inhibited the growth of 94.4%, 91.8%, and 88.3% of the isolates, respectively. Enterobacter spp. showed resistance to the beta-lactam antibiotics.(ABSTRACT TRUNCATED AT 400 WORDS)