Microbiological profile of deep tissue and bone tissue in diabetic foot osteomyelitis

Introduction: Osteomyelitis occurs by contiguous spread or direct inoculation of bacteria into bone from contiguous soft tissue infection or chronic overlying open wound. The common etiological agents in diabetic foot infections include Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli. Specimen of choice in diabetic foot osteomyelitis is bone biopsy and deep tissue. Aim: Isolation and identification of the bacteria from deep tissue and bone tissue obtained from diabetic foot osteomyelitis. To study the antibiotic susceptibility pattern of the isolated bacteria, to study the concordance of bone biopsy and deep tissue culture in the diagnosis of diabetic foot osteomyelitis and to study the biofilm formation in these pathogens. Materials and Methods: Descriptive study was conducted in the Department of Microbiology, Kasturba Medical College, Mangaluru for a period of six months from December 2016- May 2017. All the deep tissue and bone tissue samples of diabetic foot ulcer patients received in the microbiology department were processed. Results: The study included 54 bone tissue and 33 deep tissue specimens. In 31 cases, both bone and deep tissue were studied. Concordance in culture was observed in 22/31(70.96%) cases. The isolation rates of Gram negative and Gram positive organisms were 71.3% and 28.7%. The common isolates were S.aureus, Proteus spp., E.coli, Enterobacter spp., Pseudomonas spp. The rate of Methicillin Resistant Staphylococcus Aureus (MRSA) & Clindamycin resistance in S. aureus were 41% and 38%. Extended Spectrum beta lactamases (ESBL) production was seen in 27.27% of E.coli and Klebsiella spp. The rates of resistance to amikacin, ciprofloxacin and carbapenem among Gram negative bacilli were 28.5%, 23.5% and 15.58% respectively. Conclusion: The bone biopsy along with deep tissue specimen taken simultaneously would increase the accuracy of detecting the bacterial isolate and to provide effective management. The study of antibiotic susceptibility is necessary to reduce the net effect of the increasing severity of infections. Bone biopsy culture can be substituted by deep tissue samples taken during amputation or debridement.