Serratia marcescens SCH909 as reservoir and source of genetic platforms related to wide dissemination of antimicrobial resistance mechanisms

GAMBINO A; DERASPE M; ALVAREZ VE; QUIROGA MP; CORBEIL J; ROY PH; CENTRON D

FEMS MICROBIOLOGY LETTERS

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021

0378-1097

Serratia marcescens SCH909 is a multidrug-resistant strain isolated in 1988 harbouring three class 1 integrons. We wondered if these integrons were retained over time and if there were other antimicrobial resistant determinants contributing to its multidrug-resistant profile. Genomic analysis showed a fourth multidrug-resistance integron, a Tn7 transposon with dfrA1-sat2-ybeA-ybfA-ybfB-ybgA gene cassettes in the variable region. Insertion sequences were involved in the genesis of novel composite transposons in the IncL4 sub-type plasmid pSCH909, such as Tn6824 carrying an arsenic regulon and two head to head class 1 integrons surrounded by two complete IS1. Remarkably, a novel chromosomal genomic island, SmaR, was identified, closely related to Multiple Antimicrobial Resistance Regions, usually found in AbaR0-type and AbGRI2-0 from global clones of Acinetobacter baumannii, and in IncM-type plasmids circulating in Enterobacteriaceae. Maintenance studies showed that the three class 1 integrons were maintained over one month without antimicrobial pressure. These findings, and the fact that Serratia marcescens is considered a relevant nosocomial pathogen that can have a wide range of niches ? human, plant, animal, soil, and inanimate surfaces, showed the ability of this species to capture, maintain and spread a broad variety of antimicrobial resistance platforms.