Distribution and antibiotic resistance features of 532 strains of pathogens from diabetic foot infection

Abstract

Objective To investigate the microbiological profile and antibiotic susceptibility patterns of organisms isolated from diabetic foot ulcers. Methods A retrospective study was carried out on the microbiological profile and antibiotic susceptibility in 532 strains of pathogens isolated from 358 patients with diabetic foot ulcers in West China Hospital from January 1996 to December 2009. The data between groups was compared by using χ2 test. Results Foot infection occurred in 507/662 (76.6%) patients with diabetic foot. A total of 532 strains of pathogens were isolated from foot ulcers in 358/510(70.6%) patients. Gram-positive aerobes were most frequently isolated (51.4%, 281 strains), followed by gram-negative aerobes and fungus (38.7% and 8.5%, 206 and 45 strains, respectively). One hundred and thirty-six patients (26.6%) showed polymicrobial involvement. Among the 281 strains Gram-positive bacteria, 89 (16.7%) strains were Staphylococcus aureus, 48(9.0%) strains were Enterococcus, and 43(8.1%) strains were Staphylococcus epidermidis, including three strains of vancomycin resistant Enterococci(VRE) and ten strains of methicillin resistant Staphylococcus aureus(MRSA). Gram-positive bacteria were highly resistant to aztreonam (87.7%), erythromycin (83.5%), ceftriaxone (83.2%) and penicillin (81.0%); vancomycin and norfloxacin were the most effective agents against gram-positive bacteria. Among the 206 strains gram-negative bacteria, 34 strains (6.4%) were Escherichia coli, 23 strains (4.32%) were Enterobacter cloacae, 21 strains(3.9%) were Proteus vulgaris. Gram-negative bacteria were highly resistant to ampicillin(90.2%), ampicillin/sulbactam (75.3%), rifampicin (72.5%), penicillin (66.7%) and erythromycin (60.8%); Imipenem, amikacin sulphate and cefpodoxime were the most effective agents against gram-negative bacteria. The major fungus was Blastomyces albicans (2.4%, 13 strains). Conclusions Gram-positive aerobes are the predominant pathogens isolated from diabetic foot ulcers compared with gram-negative bacteria. Vancomycin and imipenem still keep highly antibacterial activity. It is very important to pay attention to pathogens survey and use antibiotics more rationally. Key words: Diabetic foot; Infection; Drug resistance, microbial