Bacteriology of diabetic foot

OBJECTIVE: To study the relative frequency of bacterial isolates cultured from diabetic foot infections and assess their comparative in vitro susceptibility to the commonly used antibacterial agents.

METHODS: This is a retrospective study with a review of the bacteriology results of specimens taken from 111 consecutive patients with diabetic foot infections at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia, during the period January 1997 to June 1999. The specimens were cultured using optimal aerobic and anaerobic microbiologic techniques. Antimicrobial susceptibility testing to different agents, was carried out using the disc diffusion method.

RESULTS: Staphylococcus aureus was the commonest isolate being recovered from 28% of cases, including methicillin resistant staphylococcus aureus in 9 of 30 (30%) patient wounds. The other organisms isolated were Pseudomonas aeruginosa (22%) and Proteus mirabilis (18%), anaerobic gram-negative organisms (11%) mainly Bacteroides fragilis. The antimicrobial susceptibility testing, showed that vancomycin was the most effective against gram-positive and and imipenem was the most effective against gram-negative organisms.

CONCLUSION: Staphylococcus aureus, Pseudomans aeruginosa, Proteus mirabilis and Bacteroides fragilis were the most common causes of diabetic foot infections. These wounds require use of combined antimicrobial therapy for initial patient management prior to susceptibility results.