Affiliation:
1. R. M. Alden Research Laboratory, Santa Monica, California
2. David Geffen School of Medicine, University of California, Los Angeles, California
3. VA Puget Sound Health Care System and University of Washington School of Medicine, Seattle, Washington
4. Merck & Co., Inc., Merck Research Laboratories, West Point, Pennsylvania
Abstract
ABSTRACT
As part of a United States-based multicenter clinical trial, conducted from 2001 to 2004, that compared ertapenem to piperacillin-tazobactam for the treatment of moderate-to-severe diabetic foot infections (DFIs), we obtained 454 pretreatment specimens from 433 patients. After debridement, the investigators collected wound specimens, mostly by curettage or biopsy, and sent them to the R. M. Alden Research Laboratory for aerobic and anaerobic culture. Among the 427 positive cultures, 83.8% were polymicrobial, 48% grew only aerobes, 43.7% had both aerobes and anaerobes, and 1.3% had only anaerobes. Cultures yielded a total of 1,145 aerobic strains and 462 anaerobic strains, with an average of 2.7 organisms per culture (range, 1 to 8) for aerobes and 2.3 organisms per culture (range, 1 to 9) for anaerobes. The predominant aerobic organisms were oxacillin-susceptible
Staphylococcus aureus
(14.3%), oxacillin-resistant
Staphylococcus aureus
(4.4%), coagulase-negative
Staphylococcus
species (15.3%),
Streptococcus
species (15.5%),
Enterococcus
species (13.5%),
Corynebacterium
species (10.1%), members of the family
Enterobacteriaceae
(12.8%), and
Pseudomonas aeruginosa
(3.5%). The predominant anaerobes were gram-positive cocci (45.2%),
Prevotella
species (13.6%),
Porphyromonas
species (11.3%), and the
Bacteroides fragilis
group (10.2%). Pure cultures were noted for 20% of oxacillin-resistant
Staphylococcus aureus
cultures, 9.2% of
Staphylococcus epidermidis
cultures, and 2.5% of
P. aeruginosa
cultures. Two or more species of
Staphylococcus
were present in 13.1% of the patients. Ertapenem and piperacillin-tazobactam were each active against >98% of the enteric gram-negative rods, methicillin-sensitive
S. aureus
, and anaerobes. Among the fluoroquinolones, 24% of anaerobes, especially the gram-positive cocci, were resistant to moxifloxacin; 27% of the gram-positive aerobes but only 6% of the members of the family
Enterobacteriaceae
were resistant to levofloxacin. Moderate-to-severe DFIs are typically polymicrobial, and almost half include anaerobes. Our antibiotic susceptibility results can help to inform therapeutic choices.
Publisher
American Society for Microbiology