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Methicillin-Resistant Staphylococcus aureus Blood Isolates Harboring a Novel Pseudo-staphylococcal Cassette Chromosome mec Element.

ABSTRACT: The aim of this work was to assess a novel pseudo-staphylococcal cassette chromosome mec (?SCCmec) element in methicillin-resistant Staphylococcus aureus (MRSA) blood isolates. Community-associated MRSA E16SA093 and healthcare-associated MRSA F17SA003 isolates were recovered from the blood specimens of patients with S. aureus bacteremia in 2016 and in 2017, respectively. Antimicrobial susceptibility was determined via the disk diffusion method, and SCCmec typing was conducted by multiplex polymerase chain reaction. Whole genome sequencing was carried out by single molecule real-time long-read sequencing. Both isolates belonged to sequence type 72 and agr-type I, and they were negative for Panton-Valentine leukocidin and toxic shock syndrome toxin. The spa-types of E16SA093 and F17SA003 were t324 and t2460, respectively. They had a SCCmec IV-like element devoid of the cassette chromosome recombinase (ccr) gene complex, designated as ?SCCmec E16SA093. The element was manufactured from SCCmec type IV and the deletion of the ccr gene complex and a 7.0- and 31.9-kb portion of each chromosome. The deficiency of the ccr gene complex in the SCCmec unit is likely resulting in mobility loss, which would be an adaptive evolutionary mechanism. The dissemination of this clone should be monitored closely.

SUBMITTER: Yoon EJ

PROVIDER: S-EPMC6450365 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Novel pseudo-staphylococcal cassette chromosome mec element (?SCCmec57395) in methicillin-resistant Staphylococcus pseudintermedius CC45.

Project description:Genetic characterization of methicillin-resistant Staphylococcus pseudintermedius (MRSP) from Thailand and Israel revealed the presence of a predominant atypical clonal lineage which was not typeable by SmaI-PFGE and SCCmec typing. All the atypical isolates (n = 34) belonged to CC45 (30 ST45 and 2 ST179 isolates, 1 ST57 isolate, and 1 ST85 isolate). The isolates originated from healthy and diseased dogs and cats, as well as from the environment of one clinic. Cfr9I-pulsed-field gel electrophoresis (Cfr9I-PFGE) and dru typing permitted the further distinction of CC45 isolates from the two different countries. Microarray analysis identified genes that confer resistance to ?-lactams (mecA; blaZ), aminoglycosides [aac(6')-Ie-aph(2')-Ia; aph(3')-III; ant(6)-Ia], macrolides and lincosamides [erm(B)], tetracyclines [tet(M)], trimethoprim [dfr(G)], streptothricin (sat4), and chloramphenicol (catpC221). Fluoroquinolone resistance was attributed to specific amino acid substitutions, i.e., Ser84Leu in GyrA and Ser80Ile and Asp84Asn in GrlA. A novel pseudo-staphylococcal cassette chromosome (?SCCmec57395) element was identified in MRSP strain 57395 (sequence type ST45) by whole-genome sequencing. The 12,282-bp ?SCCmec57395 element contained a class C1 mec gene complex but no ccr genes. In addition to the methicillin resistance gene mecA, ?SCCmec57395 also carried determinants of resistance to heavy metals, such as arsenic, cadmium, and copper. Bsu36I restriction analysis of the ?SCCmec57395 element amplified by long-range PCR revealed the presence of ?SCCmec57395 in the 33 additional isolates of MRSP CC45. The ?SCCmec57395 element represents a new class of SCCmec and has been identified in MRSP of CC45, which is a predominant clonal lineage in Israel and Thailand.

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