title: Staphylococcus aureus small colony variants in diabetic foot infections.
abstract: Background : Staphylococcus aureus (S. aureus) is one of the major pathogens causing chronic infections. The ability of S. aureus to acquire resistance to a diverse range of antimicrobial compounds results in limited treatment options, particularly in methicillin-resistant S. aureus (MRSA). A mechanism by which S. aureus develops reduced susceptibility to antimicrobials is through the formation of small colony variants (SCVs). Infections by SCVs of S. aureus are an upcoming problem due to difficulties in laboratory diagnosis and resistance to antimicrobial therapy. Methods : A prospective study was performed on 120 patients diagnosed with both type 2 diabetes mellitus and infected diabetic foot ulcers. The study was carried out from July 2012 to December 2013 in Hospital General de Mexico. The samples were cultured in blood agar, mannitol salt agar, and MacConkey agar media, and incubated at 37°C in aerobic conditions. Results : We describe the first known cases of diabetic foot infections caused by MRSA-SCVs in patients diagnosed with type 2 diabetes mellitus and infected diabetic foot ulcers. In all of our cases, the patients had not received any form of gentamicin therapy. Conclusions : The antibiotic therapy commonly used in diabetic patients with infected diabetic foot ulcers fails in the case of MRSA-SCVs because the intracellular location protects S. aureus-SCVs from the host's defenses and also helps them resist antibiotics. The cases studied in this article add to the spectrum of persistent and relapsing infections attributed to MRSA-SCVs and emphasizes that these variants may also play a relevant role in diabetic foot infections.
authors: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México.|Laboratorio de Mucosas, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, México; estrellacervantes@yahoo.com.
authors: Estrella
authors: E
authors: Cervantes-García
authors: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México.
authors: Rafael
authors: R
authors: García-Gonzalez
authors: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México.
authors: Angélica
authors: A
authors: Reyes-Torres
authors: Laboratorio de Mucosas, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, México.
authors: Aldo Arturo
authors: AA
authors: Resendiz-Albor
authors: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México.
authors: Paz María
authors: PM
authors: Salazar-Schettino
keywords: diabetic foot; infection; methicillin-resistant Staphylococcus aureus; small colony variants; ulcer