Molecular characterization of methicillin-resistant Panton-valentine leukocidin positive staphylococcus aureus clones disseminating in Tunisian hospitals and in the community

Abstract

BackgroundThe spread of MRSA strains at hospitals as well as in the community are of great concern worldwide. We characterized the MRSA clones isolated at Tunisian hospitals and in the community by comparing them to those isolated in other countries.ResultsWe characterized 69 MRSA strains isolated from two Tunisian university hospitals between the years 2004-2008. Twenty-two of 28 (79%) community-associated MRSA (CA-MRSA) strains and 21 of 41 (51%) healthcare-associated MRSA (HA-MRSA) strains were PVL-positive. The PVL-positive strains belonged to predicted founder group (FG) 80 in MLST and carried either type IVc SCCmec or nontypeable SCCmec that harbours the class B mec gene complex. In contrast, very diverse clones were identified in PVL-negative strains: three FGs (5, 15, and 22) for HA-MRSA strains and four FGs (5, 15, 45, and 80) for CA-MRSA strains; and these strains carried the SCCmec element of either type I, III, IVc or was nontypeable. The nucleotide sequencing of phi7401PVL lysogenized in a CA-MRSA strain JCSC7401, revealed that the phage was highly homologous to phiSA2mw, with nucleotide identities of more than 95%. Furthermore, all PVL positive strains were found to carry the same PVL phage, since these strains were positive in two PCR studies, identifying gene linkage between lukS and mtp (major tail protein) and the lysogeny region, both of which are in common with phi7401PVL and phiSa2mw.ConclusionsOur experiments suggest that FG80 S. aureus strains have changed to be more virulent by acquiring phi7401PVL, and to be resistant to β-lactams by acquiring SCCmec elements. These novel clones might have disseminated in the Tunisian community as well as at the Tunisian hospitals by taking over existing MRSA clones.

Antibiograms, toxin profiling and molecular typing of Staphylococcus aureus isolates from two tertiary hospitals in Jordan

“…Similar results were reported by Ramdani-Bouguessa et al [49] who reported that pvl was the most detected toxin gene (72%) of the tested clinical isolates. Similar results were also reported from a Tunisian study [50] where 79% of the community acquired MRSA contained the pvl gene while 51% of the health care associated MRSA infections contained the pvl gene. However, as with distribution of antibiotic resistance, toxin distribution varied between studies from different areas of the world.…”

“…For instance, following AluI digestion, 61 MRSA isolates were clustered in genotype C rather than genotype A. Similar changes in the cluster arrangement were observed when a dendrogram was constructed for MRSA isolates restricted with Cfo I where the majority of isolates (50) were clustered in genotype A rather than genotype D.…”

Panton-Valentine Leukocidin (PVL)-Positive Health Care-Associated Methicillin-Resistant Staphylococcus aureus Isolates Are Associated with Skin and Soft Tissue Infections and Colonized Mainly by Infective PVL-Encoding Bacteriophages

“…However, the PVL marker for CA-MRSA was disputed in recent years, not only because the PVL-positive rates in CA-MRSA recovered from certain regions were Ͻ10% (27), but also because HA-MRSA was also confirmed to carry the PVL genes. Mariem et al (9) reported that 21 of 41 (51%) HA-MRSA strains were positive for PVL in Tunisian hospitals, and another study reported that 5.7% of the HA-MRSA isolates were PVL positive in Asian countries (10). The increasing prevalence of PVL-encoding HA-MRSA is a serious concern that may worsen MRSA infections.…”

“…The increasing carriage of PVL genes in a certain MRSA lineage may result from the spread and transfer of PVL-encoding phages. Using the available PVL phage-specific primers (14)(15)(16)18), we characterized 59 PVL-encoding phages belonging to various phage groups, whereas the remaining phages in 15 PVL-positive MRSA isolates were not determined, which would indicate the existence of new PVL-encoding phages that have yet to be characterized, such as the recently characterized PVL phages ⌽IND772 and ⌽7401 (9,29). We also determined that hospital-onset HA-MRSA isolates were colonized mainly by PVL phages with high infectivity, such as ⌽7247PVL, ⌽SLT, and ⌽Sa2958, which might explain the increasing prevalence of PVL in HA-MRSA isolates.…”

Clonal lineages detected amongst tetracycline-resistant meticillin-resistant Staphylococcus aureus isolates of a Tunisian hospital, with detection of lineage ST398

“…Currently, there are no data about the presence of MRSA CC398 in Muslim countries, in which pork is not consumed. Thus, in Tunisia, some reports have described the detection of different clonal lineages of MRSA in samples from human and animal origins (Ben Nejma et al, 2013;Ben Slama et al, 2011;Gharsa et al, 2012;Kechrid et al, 2011;Mariem et al, 2013). However, no MRSA ST398 isolates have been identified in hospitals in Tunisia.…”