Detecting aerobic bacterial diversity in patients with diabetic foot wounds using ERIC-PCR: a preliminary communication.

The polymicrobial nature of diabetic foot infection is a reflection of the immune compromised state of the host.The methods of microbial identification based on colony morphology and biochemical characteristics have limitations as they may not differentiate the diverse microorganisms that infect foot wounds. The aim of the present study was to find out the bacterial diversity in diabetic foot infections at genetic level by finger printing, that is, ERIC-PCR (enterobacterial repetitive intergenic consensus -polymerase chain reaction). Nine patients with infected diabetic foot ulcers were recruited to the study. Pus and tissue samples were collected from the wound site. Aerobic bacteria were isolated employing standard microbiological culture methods and their genetic variability was analyzed using the ERIC-PCR. Sensitivity test for these isolates against commonly used antibiotics were performed using disc diffusion method. The standard microbiological culture technique yielded 38 morphotypes of bacteria and their genetic diversity was confirmed by ERIC-PCR assay. Analysis of the similarity index using NTSYSpc 2.1 software revealed 34 types of banding pattern among these isolates. Based on the similarity index these isolates were divided into 7 groups. As many as 8 types of aerobic bacterial isolates were detected from a single patient using the above technique compared with 2 on routine culture analysis. Genetically diverse isolates showed differential sensitivity pattern against commonly used antibiotics in the assay. The observed diversity at genetic level is attributed to variable sensitivity pattern of these isolates against the class of antibiotics. A molecular technique such as ERIC-PCR is a more sensitive detection method than conventional techniques, the potential of which needs to be fully understood.