Sensibilidad a los antimicrobianos de micobacterias de crecimiento rápido mediante el método E-test / Assessment of in vitro susceptibility to antimicrobials of rapidly growing mycobacteria by E-test

ABSTRACT

Background: Rapidly growing mycobacteria (RGM) are considered opportunistic pathogens. An increasing number of post traumatic or surgical infections are caused by these microorganisms. Aim: To determine the antimicrobial susceptibility of RGM using the E-test method. Material and methods: A total of 54 isolates of RGM was obtained from several clinical samples and selected for this study Strains were identified to the species level by phenotypic and biochemical characteristics, PCR-restriction enzyme analysis of the hsp65 gene (PRA) and sequencing of the 16S rRNA. Susceptibility was investigated by E-test to amikacin, cefoxitin, ciprofioxacin, clarithromycin, imipenem, quinupristin/dalfopristin, linezolid and tigecycline. Results: Twelve different species of RGM were identified: Mycobacterium fortuitum (23 strains), M chelonae (11), M abscessus (10), Msenegalense (2), Malvei (1), Mbrumae (1), Mmageritense (1), mucogenicum (1), M neoaurum (1), Mperegrinum (1), M septicum (1) y M smegmatis (1). All the strains were inhibited by low concentrations of amikacin and tigecycline. Susceptibility to cefoxitin, fluoroquinolones, clarithromycin, imipenem and linezolid was variable. All but two strains were resistant to quinupristin/ dalfopristin. Conclusions: Due to the uneven antimicrobial susceptibility of different species of RGM, an antimicrobial susceptibility test is mandatory for these microorganisms. The E-test method is well suited to determine minimum inhibitory concentrations.