1421. Microbiology and Resistance of Diabetic Foot Osteomyelitis in a Teaching Hospital in Santiago, Chile

Abstract

Background. Diabetic foot ulcers are a frequent complication of patients with diabetes mellitus, two-thirds of these can become infected and up to 50% can develop a deep infection and osteomyelitis, which usually requires surgical management and prolonged antibiotic therapy. Microbiology is characterized by a predominance of Gram-positive (Staphylococcus aureus and negative coagulase), followed by enterobacteria and non-fermentors such as P. aeruginosa, but it is variable and factors such as the type of patient, wound characteristics, use of antibiotics, and the environment. In Chile, there are no recent data on microbiology or resistance in diabetic foot osteomyelitis, which is fundamental for the rational use of antibiotics. The objective of this study was the description of this microbiology and resistance in a teaching hospital in Santiago, Chile. Methods. Retrospective study conducted at the DIPRECA Hospital. Residual bone cultures taken from the operating room were analyzed, from patients hospitalized for diabetic foot osteomyelitis between January 1, 2013 and December 31, 2018. Sex, age, the microorganism isolated in bone and its resistance profile were analyzed. The study is approved by the Hospital Ethics Committee. Results. We analyzed 285 cultures of 107 patients. The mean age was 71 ± 9 years and 82% corresponded to male patients. 26% of the cultures were polymicrobial. Gram-positive cocci corresponded to 68.4% and gram-negative bacilli to 31.6%. The main microorganism were E. faecalis 24.2%, S. aureus 21.8%, S. coagulase negative 18.9%, P. aeruginosa in 6.3%, K. pneumoniae in 6% and E. coli in 3.5%. In relation to resistance, E. faecalis were 98.2% sensitive to ampicillin, S. aureus were 55.5% sensitive to cefoxitin and 100% to vancomycin, S. coagulase negative were 41% sensitive to oxacillin and 100% vancomycin, P. aeruginosa were 73% sensitive to imipenem and 66% sensitive to meropenem, K. pneumoniae was 87% ESBL, 100% sensitive to imipenem and 73% to meropenem and E. coli was 63% ESBL and 100% sensitive to carbapenems. Conclusion. Osteomyelitis of the diabetic foot was characterized as being mainly monomicrobial, by E. faecalis, Staphylococcus, P. aeruginosa, and K. pneumoniae, with a high prevalence of resistance to methicillin, ESBL and to a lesser extent resistance to carbapenems. (Figure Presented).