Molecular Epidemiology of Methicillin-Resistant Staphylococcus hominis (MRSHo): Low Clonality and Reservoirs of SCCmec Structural Elements

Abstract

BackgroundMethicillin resistant Staphylococcus hominis (MRSHo) are important human pathogens in immunocompromised patients. However, little is known regarding its population structure and staphylococcal chromosomal cassette mec (SCCmec) content.Methodology/Principal FindingsTo assess the population structure and the SCCmec content of S. hominis, 34 MRSHo and 11 methicillin-susceptible S. hominis (MSSHo) from neutropenic patients collected over a 3-year period were studied. The genetic backgrounds of S. hominis isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and SCCmec types were determined by PCR. Cassette chromosome recombinases (ccr) were characterized by PCR and ccrB sequencing. The 34 S. hominis isolates were classified into as many as 28 types and 32 subtypes (SID = 99.82%); clonal dissemination was occasionally observed. The main SCCmec structures identified were SCCmec type VI (4B) (20%), SCCmec VIII (4A) (15%), and a new SCCmec composed of mec complex A in association with ccrAB1 (38%); 27% of the isolates harbored non-typeable SCCmec. Overall, a high prevalence of mec complex A (73.5%), ccrAB1 (50%) and ccrAB4 (44%) were found. Importantly, ccrB1 and ccrB4 from both MRSHo and MSSHo showed a high nucleotide sequence homology with those found in S. aureus SCCmec I, VI and VIII respectively (>95%).Conclusions/SignificanceThe S. hominis population showed a limited clonality and a low genetic diversity in the allotypes of ccr and classes of mec complex. Moreover, our data suggest that S. hominis might have been a privileged source of mec complex A, ccrB1 and ccrB4, for the assembly of primordial SCCmec types.

Coagulase-Negative Staphylococci

“…(i) SCC elements such as SCC 12263 , which was found in S. hominis, possess a ccr complex but lack mecA (481). For S. hominis and S. haemolyticus, it was shown that these species might contain many other potential SCC elements as putative reservoirs of SCCmec structural elements (482,483). (ii) As a result of deletion events or representing precursors of known SCCmec elements, pseudo (⌿)-SCCmec elements harbor mecA but lack the ccr gene complex; an example is the S. xylosus ⌿SCCmec S04009 element, which carries the class E mec gene complex, similar to type XI SCCmec, but lacks the ccr gene complex and both J regions (474).…”

Antibiotics Sensitivity Profile Towards <i>Staphylococcus hominis</i> in Assir Region of Saudi Arabia

“…A zone of inhibition measuring ≤15 mm in Mueller-Hinton agar or ≤11 mm on Trypticase soya agar plates was considered indicative of novobiocin resistance [10].…”

The Evolution and Dissemination of Methicillin Resistance Determinant in Staphylococcus aureus

“…SCCmec type IV is the common structure found in S. epidermidis, while other SCCmec types I, II, III, V, VI and non-typeable SCCmec were also detected at a lower rate [61,62]. For S. haemolyticus, SCCmec type V predominated in combination with other novel SCCmec types [60,63]. In S. hominis, SCCmec types contained a combination of novel non-typeable SCCmec, SCCmec types VI, VIII, III, and other elements [35,61].…”

“…They assigned these untypeable SCCmec elements as UT1-UT10 [35]. In addition, another study also described new SCCmec types in Staphylococcus hominis and described those as NT1till NT4 [60].…”