[Risk factors for infections of methicillin-resistant Staphylococci in diabetic foot patients]

To examine the distribution patterns of pathogens isolated from the patients with diabetic foot ulcers and explore the risk factors for infections of methicillin-resistant S. aureus (MRSA) or methicillin-resistant S. epidermidis (MRSE).

A total of 388 diabetic-foot patients hospitalized at Tianjin Metabolic Diseases Hospital between January 2008 and June 2010 were recruited. The distribution profiles of pathogens isolated from diabetic foot ulcers were summarized. The patients with S. aureus infections were divided into MRSA and MSSA groups while those with S. epidermidis infections into MRSE and MSSE groups. The clinical features of these patients were compared between all groups. Logistic regression was employed to identify the risk factors for the MRSA/MRSE infections.

A total of 362 pathogens were isolated from them. And the Gram-positive bacteria were the most predominant (57.2%, 207/362), followed by Gram-negative bacilli (39.2%, 142/362) and true fungi (3.6%, 13/362). The three most frequently isolated pathogens were S. aureus (27.1%), S. epidermidis (18.8%) and Pseudomonas aeruginosa (15.5%). Statistically significant differences existed in antibiotic usage in 6 months prior to hospitalization, course of ulcer, ulcer size, deep ulcer, osteomyelitis, hypertension, anemia, hypoproteinemia and erythrocyte sedimentation rate between the patients infected with MRSA and MSSA (P < 0.05). The MRSE infection was correlated with recurrent ulcer, osteomyelitis, hypoproteinemia, HbA1c and lower total serum protein (P < 0.05). Multiple Logistic regression analysis revealed that antibiotic usage in 6 months prior to hospitalization, long course of ulcer, osteomyelitis, hypertension and hypoproteinemia were risk factors for the MRSA infection. And HbA1c was a risk factor for the MRSE infection.

In the present study, the Gram-positive cocci are the main pathogens isolated from diabetic foot ulcers. And S. aureus and S. epidermidis are the most frequently isolated pathogens. Antibiotic usage in 6 months prior to hospitalization, long course of ulcer, osteomyelitis, hypertension and hypoproteinemia are risk factors for the MRSA infection. And HbA1c is a risk factor for the MRSE infection.