Molecular basis of resistance to macrolides, lincosamides and streptogramins in Staphylococcus saprophyticus clinical isolates

Abstract

The aim of this study was to evaluate the prevalence of resistance to macrolide-lincosamide-streptogramin (MLS) antibiotics as well as to assess the molecular basis of this resistance amongst 72 Staphylococcus saprophyticus urinary isolates collected from 2005 to 2009 in University Hospital of Caen (France). Of the 72 strains studied, 33 (45.8%) were resistant to at least one MLS antibiotic, including 24 (72.7%) with an M phenotype, 5 (15.2%) with an inducible MLS(B) phenotype, 3 (9.1%) with a combined M+L phenotype and 1 (3.0%) with an L phenotype. All isolates were susceptible to the combination of streptogramins A and B. The resistance genes erm(A), erm(B), erm(C), msr(A) and lnu(A) were detected alone in 0, 0, 5 (15.2%), 24 (72.7%) and 1 (3.0%) of the 33 MLS-resistant isolates, respectively, whereas 2 strains (6.1%) were positive for both msr(A) and lnu(A). All msr(A)-positive isolates exhibited an M phenotype, whereas all five erm(C)-positive and all three lnu(A)-positive strains displayed, respectively, an inducible MLS(B) phenotype and an L phenotype with a positive Hodge test. Plasmid analysis indicated that erm(C) and lnu(A) genes were borne by small-size plasmids (ca. 2.5 kb), whereas larger plasmids (30-90 kb) harboured msr(A). In conclusion, these findings show a high prevalence of MLS resistance in S. saprophyticus, which was mainly associated with the presence of the msr(A) gene. Since S. saprophyticus colonises the gastrointestinal tract, it may constitute an unexpected reservoir for MLS resistance genes, in particular msr(A), amongst coagulase-negative staphylococci.

Resistance to Macrolide Antibiotics in Public Health Pathogens

“…Macrolide resistance in MRSA is significantly higher than in methicillin-susceptible S. aureus (MSSA) and, in a recent study in Turkey, there was a sevenfold difference in macrolide resistance between MRSA and MSSA (Gul et al 2008;Yildiz et al 2014;Aydeniz Ozansoy et al 2015). The rates of macrolide resistance in coagulase-negative staphylococci vary from 44% (Staphylococcus saprophyticus, France, Le Bouter et al 2011) to 100% (S. haemolyticus, Poland, Brzychczy-Wloch et al 2013S. hominis, Poland, Szczuka et al 2015) in surveillance studies (Table 2).…”

Clonality, virulence and the occurrence of genes encoding antibiotic resistance among Staphylococcus warneri isolates from bloodstream infections

“…genes, PCR assays were performed as described by Geha et al (1994), Ardic et al (2006) and Le Bouter et al (2011).…”

“…The mecA gene that encodes an alternative binding protein with decreased binding affinity to meticillin, and others for beta-lactam antibiotics, are part of a mobile genetic element called the staphylococcal chromosome mec (SCCmec). The genes code for methylases, erm(A)and erm (B), that modify the target site in 23S rRNA and thereby inhibit the binding of macrolide-lincosamide streptogramin B (MLS B ) antibiotics, and are associated with transposons Tn554 and Tn917/ Tn551, while the erm(C) gene was identified on small plasmids (Le Bouter et al, 2011). The lnu(A) gene encodes a lincosamide nucleotidyltransferase, which confers resistance to lincosamides and is located on small plasmids.…”

Characterization of sal (A), a Novel Gene Responsible for Lincosamide and Streptogramin A Resistance in Staphylococcus sciuri

“…While S. sciuri and sal(A) cannot be seen as immediate threats to public health, both should be included in the monitoring memos for MLS antibiotic resistance surveys. In addition, the report of the presence of a sal(A)-related pseudogene in S. saprophyticus might be of epidemiological concern, especially since none of the thus-far-described resistance genes can be found in an ML-resistant strain (36). Indeed, it was recently reported that only one nucleotide mutation within a resident cryptic AREencoding gene of the Enterococcus faecium genome would be enough to generate an LS A -resistant strain from a susceptible one (37).…”