Serratia marcescens bacteremia: clinical features and antimicrobial susceptibilities of the isolates.

From July 1996 to June 1997, 22 adult patients with Serratia marcescens bacteremia were retrospectively studied at China Medical College Hospital. All patients had severe underlying disease, most commonly diabetes mellitus. Eighteen (82%) patients had nosocomial infection. Clinical syndromes included primary bacteremia (68%), pneumonia (14%), urinary tract infection (9%), suppurative thrombophlebitis (5%) and surgical wound infection (5%). Twelve patients had central venous catheters in place at the onset of bacteremia, but only one case met the definition of catheter-related infection. In 14 (64%) patients, portal of entry of S. marcescens infection was unknown. Five (23%) patients had concurrent polymicrobial bacteremia. The overall mortality rate was 50% (11/22). Seven (32%) of the 22 patients died of S. marcescens bacteremia. All isolates were resistant to ampicillin and cephalothin and susceptible to imipenem. Ninety-five percent of strains were susceptible to moxalactam, 68% to amikacin, 55% to ceftazidime, 45% to aztreonam, 32% to ceftriaxone, 27% to gentamicin, 18% to cefoperazone and cefotaxime, and 9% to piperacillin. MICs of various antibiotics demonstrated that ciprofloxacin and imipenem had good activities against S. marcescens, with MIC90 of 0.19 microg/mL and 1.0 microg/mL, respectively. Due to increasing multidrug resistance, choosing appropriate antimicrobial agents such as moxalactam, imipenem, and ciprofloxacin should be highly recommended for the treatment of S. marcescens infections.