Smqnr VARIANTS IN CLINICAL ISOLATES OF Stenotrophomonas maltophilia IN BRAZIL

Abstract

SUMMARYStenotrophomonas maltophilia contains a novel chromosomally-encoded qnr gene named Smqnr that contributes to low intrinsic resistance to quinolone. We described Smqnr in 13 clinical isolates of S. maltophilia from two Brazilian hospitals, over a 2-year period. The strains were identified by API 20 NE (bioMérieux, France). Susceptibility by microdilution method to trimetroprim/ sulfamethoxazole, ciprofloxacin, levofloxacin, minocycline, ceftazidime, chloramphenicol and ticarcillin/clavulanate was performed according to CLSI. PCR detection of Smqnr gene was carried out. The sequence of Smqnr was compared with those deposited in GenBank. Pulsed-field gel electrophoresis (PFGE) of all strains was performed. Thirteen Smqnr positives isolates were sequenced and three novel variants of Smqnr were identified. All 13 Smqnr isolates had distinguishable patterns by PFGE. This is the first report of Smqnr in S. maltophilia isolated in Brazil.

Transferable Mechanisms of Quinolone Resistance from 1998 Onward

“…Thus, 11 different alleles were sequenced when SmQnr was detected (368). This finding was thereafter confirmed (369,370), and as mentioned above (see "Qnr Classification"), the development of a website repository to bring order to the SmQnr nomenclature was proposed (320). The number of SmQnr alleles has increased enormously in the last years, with ϳ150 different SmQnr alleles being detected in a GenBank search performed at the time of this review.…”

Comparative Genomics of Environmental and ClinicalStenotrophomonas maltophiliaStrains with Different Antibiotic Resistance Profiles

“…No correlation could be made between the presence or absence of a given antibiotic resistance gene and the resistance profile of an S. maltophilia strain. Indeed, substantially all known antibiotic resistance determinants such as bla L1 coding a metallo-β-lactamase responsible for the resistance toward imipenem ( Walsh et al 1994 ), bla L2 and amp C conferring resistance against cephalosporins and penicillins ( Walsh et al 1997 ; Yang et al 2009 ), Sm qnr conferring low intrinsic resistance against quinolones ( Sanchez et al 2008 ; Gracia-Paez et al 2013 ) and aph (3′)-IIc encoding an aminoglycoside phosphotransferase enzyme that increases resistance against kanamycin, neomycin, butirosin and paromomycin ( Okazaki and Avison 2007 ), were found among all the strains regardless of their antibiotic resistance profiles or isolation origins. Comparative genomic studies of the MDR origin with other opportunistic pathogens did shed light on major differences in the antibiotic resistance gene content between resistant and sensitive strains ( Fournier et al 2006 ; Kumar et al 2011 ), but in S. maltophilia , most of identified antibiotic resistance genes were present in all the genomes.…”