Staphylococcus aureus small colony variants in diabetic foot infections
Por:
Cervantes-García E., García-Gonzalez R., Reyes-Torres A., Resendiz-Albor A.A., Salazar-Schettino P.M.
Publicada:
1 ene 2015
Resumen:
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 degrees 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.
Filiaciones:
Departamento de Microbiología y Parasitología, Universidad Nacional Autónoma de México, México City, Mexico
Laboratorio de Mucosas, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, Mexico
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