title: Infection after elective colorectal surgery: bacteriological analysis of failures in a randomized trial of cefotetan vs. ertapenem prophylaxis.
abstract: BACKGROUND
  A randomized study comparing single-dose cefotetan and ertapenem prophylaxis for elective colorectal surgery in 1,002 patients found ertapenem to be significantly more effective (p < 0.001). Failures of prophylaxis were thought to involve organisms resistant to both antimicrobial agents, isolated most often from deep or superficial incision sites.
  
  
  METHODS
  Further testing and analysis of the microbial data was performed. Susceptibility results were correlated with the clinical outcomes reported previously.
  
  
  RESULTS
  Of the 216 aerobes tested, 62.6% were resistant to cefotetan and 44% to ertapenem. Enterococci and methicillin-resistant Staphylococcus epidermidis were the aerobes recovered most frequently, and Bacteroides thetaiotaomicron, Clostridium innocuum, and Eubacterium lentum were the most frequent anaerobes. Enterococcus faecalis usually was associated in mixed culture with Bacteroides fragilis group species. Approximately one-half of the 158 anaerobes (50.7%), including all the species above, were resistant to cefotetan; most of these (61.4%) came from superficial incision sites. Only one anaerobe (Desulfovibrio fairfieldensis), found in a superficial incisional infection, was resistant to ertapenem, and no ertapenem-resistant enteric bacteria were recovered. In vitro resistance was associated with therapeutic failure.
  
  
  CONCLUSIONS
  The in vitro activity of ertapenem was superior to that of cefotetan against all anaerobic and many aerobic bacteria isolated from postoperative cultures of patients who failed prophylaxis with these agents. Our findings help to elucidate the results of the clinical trial.
authors.affiliation: R. M. Alden Research Laboratory, Santa Monica, California 90404, USA. ejcgmd@aol.com
authors.forename: Ellie J C
authors.initials: EJ
authors.lastname: Goldstein
authors.forename: Diane M
authors.initials: DM
authors.lastname: Citron
authors.forename: C Vreni
authors.initials: CV
authors.lastname: Merriam
authors.forename: Murray A
authors.initials: MA
authors.lastname: Abramson
mesh_terms: D019072:Antibiotic Prophylaxis; D001419:Bacteria / Q000187:drug effects*; D001420:Bacteria, Aerobic / Q000187:drug effects; D001421:Bacteria, Anaerobic / Q000187:drug effects; D001424:Bacterial Infections / Q000453:epidemiology / Q000382:microbiology; D015313:Cefotetan / Q000494:pharmacology / Q000627:therapeutic use*; D003106:Colon / Q000601:surgery*; D017558:Elective Surgical Procedures; D000077727:Ertapenem; D006801:Humans; D008826:Microbial Sensitivity Tests; D012007:Rectum / Q000601:surgery*; D013530:Surgical Wound Infection / Q000453:epidemiology / Q000382:microbiology*; D017211:Treatment Failure; D047090:beta-Lactams / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D047090:beta-Lactams; D015313:Cefotetan; D000077727:Ertapenem