Proposal that Mycobacterium massiliense and Mycobacterium bolletii be united and reclassified as Mycobacterium abscessus subsp. bolletii comb. nov., designation of Mycobacterium abscessus subsp. abscessus subsp. nov. and emended description of Mycobacterium abscessus

Comparative study with two different enrichments in the culture media used in the disinfectant efficacy assay

Recent changes in Brazilian legislation for commercial disinfectants have been published due to the recent epidemic of nosocomial infections caused by rapidly growing mycobacteria (RGM) in many states of Brazil over the last 8years. One of these documents requires that all the manufacturers provide evidence of efficacy of sterilizing and disinfectant products, used for semi critical medical devices, against the Mycobacterium bovis BCG Moreau and Mycobacterium abscessus subsp. bolletii INCQS 00594 strains by using the Confirmative in vitro Test for Determining Tuberculocidal Activity of Disinfectants recommended by the Association of Official Analytical Chemists. These changes have caused additional costs and increased problems for importation of enrichment products at national laboratories where disinfectant efficacy assay service is performed. Middlebrook ADC Enrichment (ADC) is provided by a unique manufacturer and used in the official protocol. The aim of the present study was to evaluate an alternative in house low-cost enrichment composed of fetal bovine serum and glucose (FBSG) with ADC for performance of disinfectant efficacy assay against mycobacteria. After obtaining the growth curves for M. abscessus ATCC 19977, M. abscessus subsp. bolletii INCQS 00594, Mycobacterium chelonae ATCC 35752, and Mycobacterium fortuitum ATCC 6841 by using ADC enrichment and FBSG in Kirchners and 7H9 culture media. Through statistical analysis via the Kruskal-Wallis test on the evaluation of microorganism growth rate, it was observed that there was no inhibition of RGM growth by any of the enrichments used. These results suggest that low-cost enrichment FBSG may be used as a potential substitute of ADC for composition of media for mycobacterial growth, including in disinfectant tests.

Phenotypic and molecular characterization of quinolone resistance in Mycobacterium abscessus subsp. bolletii recovered from postsurgical infections

Several outbreaks of infections caused by rapidly growing mycobacteria (RGM) were reported in many Brazilian states (2032 notified cases) from 2004 to 2010. Most of the confirmed cases were mainly associated with Mycobacterium massiliense (recently renamed as Mycobacterium abscessus subsp. bolletii) BRA100 clone, recovered from patients who had undergone invasive procedures in which medical instruments had not been properly sterilized and/or disinfected. Since quinolones have been an option for the treatment of general RGM infections and have been suggested for therapeutic schemes for these outbreaks, we evaluated the in vitro activities of all generations of quinolones for clinical and reference RGM by broth microdilution, and analysed the peptide sequences of the quinolone resistance determining regions (QRDRs) of GyrA and GyrB after DNA sequencing followed by amino acid translation. Fifty-four isolates of M. abscessus subsp. bolletii, including clone BRA100, recovered in different states of Brazil, and 19 reference strains of RGM species were characterized. All 54 M. abscessus subsp. bolletii isolates were resistant to all generations of quinolones and showed the same amino acids in the QRDRs, including the Ala-83 in GyrA, and Arg-447 and Asp-464 in GyrB, described as being responsible for an intrinsic low level of resistance to quinolones in mycobacteria. However, other RGM species showed distinct susceptibilities to this class of antimicrobials and patterns of mutations contrary to what has been traditionally defined, suggesting that other mechanisms of resistance, different from gyrA or gyrB mutations, may also be involved in resistance to high levels of quinolones.

Diversity of pulsed-field gel electrophoresis patterns of Mycobacterium abscessus type 2 clinical isolates

An epidemic of infections by rapidly growing mycobacteria related to surgical procedures between 2004 and 2008 in Brazil was caused by a unique strain showing the Mycobacterium abscessus type 2 pattern when it was analyzed by the molecular method of PCR-restriction enzyme analysis of the hsp65 gene (PRA-hsp65). In order to investigate the diversity of M. abscessus type 2 clinical isolates and to assess whether this epidemic strain was present in specimens from nonsurgical patients, we studied 52 isolates from 38 patients showing this characteristic PRA-hsp65 pattern obtained between 2005 and 2009. All isolates were identified by sequencing of region V of the rpoB gene and typed by pulsed-field gel electrophoresis (PFGE) using two restriction enzymes, DraI and AseI. Seven isolates obtained from sputum, bronchoalveolar lavage fluid, and urine in three different Brazilian states showed rpoB sequences 100% similar to the rpoB sequence of epidemic strain INCQS 594 and PFGE patterns highly related to the patterns of isolates, evidencing the presence of the epidemic strain in isolates from patients not associated with the surgical epidemic. The remaining isolates showed diverse rpoB sequences, with the highest similarities being to the corresponding sequences of M. massiliense(T) CIP 108297 (21 isolates), M. bolletii(T) CIP 108541 (19 isolates), or M. abscessus(T) ATCC 19977 (5 isolates). Two additional clusters could be detected by PFGE. PFGE showed 100% typeability and reproducibility and discriminatory powers, calculated by Simpson's index of diversity, of 0.978 (DraI) and 0.986 (AseI), confirming its suitability for the discrimination of M. abscessus type 2 isolates.