Current Status of Staphylococcal Cassette Chromosome mec (SCCmec)

Staphylococcal cassette chromosome mec (SCCmec) typing was established in the 2000s and has been employed as a tool for the molecular epidemiology of methicillin-resistant Staphylococcus aureus, as well as the evolution investigation of Staphylococcus species. Molecular cloning and the conventional sequencing of SCCmec have been adopted to verify the presence and structure of a novel SCCmec type, while convenient PCR-based SCCmec identification methods have been used in practical settings for many years. In addition, whole-genome sequencing has been widely used, and various SCCmec and similar structures have been recently identified in various species. The current status of the SCCmec types, SCCmec subtypes, rules for nomenclature, and multiple methods for identifying SCCmec types and subtypes were summarized in this review, according to the perspective of the International Working Group on the Classification of Staphylococcal Cassette Chromosome Elements.

Characterizing a novel SCC mec with a composite structure from a clinical strain of Staphylococcus hominis , C34847

Staphylococcal cassette chromosome mec (SCC mec ) has predominantly been described in methicillin-resistant Staphylococcus aureus . However, studies have indicated that coagulase-negative staphylococci (CoNS) carry a larger diversity of SCC elements. We characterized a composite SCC mec element carrying an uncharacterized ccr1 and type A mec gene combination, in conjunction with a secondary element bearing ccr4 , from a clinical strain of S. hominis . The element’s complex structure points to a high degree of recombination occurring in SCC mec in CoNS.

Draft Genome Sequence of Methicillin-Resistant Staphylococcus aureus Harboring Staphylococcal Cassette Chromosome mec Type IX, Isolated from a Fatal Bacteremic Pneumonia Case

Here, we report the whole-genome sequence of a methicillin-resistant Staphylococcus aureus strain harboring staphylococcal cassette chromosome mec (SCC mec ) type IX, isolated from a fatal sepsis case. Genomic analysis revealed that the isolate was sequence type 9 and spa type t3446, carrying multiple antimicrobial-resistant genes comprising mecA , blaZ , aac(6′)-aph(2″) , aadD , ant(6)-Ia , lsa (E), dfrG , tet (M), fexA , and lnu (B).

Complete Circular Genome Sequence of a mecB- and mecD -Containing Strain of Macrococcus canis

The complete genome sequence of Macrococcus canis strain 19/EPI0118, isolated from a veterinary clinic environment in Switzerland, was determined using hybrid assembly of Oxford Nanopore and Illumina reads. 19/EPI0118 harbored the methicillin resistance genes mecB and mecD on a staphylococcal cassette chromosome mec element and a Macrococcus chromosomal resistance island, respectively.

The SCCmec Types and Antimicrobial Resistance among Methicillin-Resistant Staphylococcus Species Isolated from Dogs with Superficial Pyoderma

This study characterizes clinical methicillin-resistant staphylococcal (MRS) isolates obtained from superficial pyoderma infections in dogs. Our interest was to determine the staphylococcal cassette chromosome mec (SCCmec) type and the antimicrobial susceptibility among MRS isolates from clinical cases. Skin swabs were collected and cultured. Staphylococcus species were identified and characterized with biochemical tests and MALDI-TOF-MS and antimicrobial susceptibility testing by disk diffusion. mecA detection and staphylococcal cassette chromosome mec (SCCmec) typing were achieved by PCR. Of the 65 clinical samples, 56 (86.2%) staphylococcal infections were identified. Twelve (21%) of 56 isolates were MRS infections. All MRS isolates were multidrug resistant. The ccrC and class-C2 mec, which were SCCmec type V, were the most prevalent (66.7%) among the 12 MRS isolates. The predominant SCCmec type V was found in S. aureus, S. intermedius group, S. lentus, S. xylosus, and S. arlettae. Treatment failure is a concern with the emergence of highly resistant MRS in dogs associated with superficial pyoderma. The detection of type V SCCmec MRS has previously been reported among veterinarians and dog owners but not in Northern Thailand. These infections serve as a reminder to improve infection prevention and control measures including reducing environmental contamination and potential zoonotic exposures to MRS. In addition, educational awareness of these risks in small animal hospitals needs to be increased among veterinary hospital staff, clients, and patients.

Vancomycin heteroresistance in Staphylococcus haemolyticus: elusive phenotype

Aim: To determine the presence of vancomycin heteroresistance in Staphylococcus haemolyticus. Materials & methods: A total of 48 rifampicin-resistant S. haemolyticus isolates from bloodstream infections were included. Vancomycin heteroresistance was determined using the population analysis profile-area under curve (PAP-AUC) method. All the isolates were screened for the presence of mecA gene, mutations in the rpoB gene, staphylococcal cassette chromosome mec and multilocus sequence types. Results: Fifteen isolates were identified as heteroresistant vancomycin-intermediate S. haemolyticus using PAP-AUC method. Dual rpoB mutations (D471E and I527M) contributed for the rifampicin resistance. The sequence types of heteroresistant vancomycin-intermediate S. haemolyticus were highly diverse. Conclusion: These findings illustrate the potential of S. haemolyticus to develop heteroresistance, which emphasizes the need for routine surveillance of S. haemolyticus isolated from intensive care units for infection control practices.

Association between fluoroquinolone resistance and MRSA genotype in Alexandria, Egypt

Antimicrobial stewardship isn’t strictly observed in most Egyptian hospitals, raising antibiotic resistance. Epidemiology of Egyptian MRSA isolates, or associations with resistance to other antibiotics remain largely unknown. We identified MRSA genotypes in Alexandria Main University Hospital (AMUH) and investigated rates of moxifloxacin resistance, an alternative MRSA treatment, among different genotypes. Antibiotic susceptibility of 72 MRSA clinical isolates collected in 2015 from AMUH was determined by disc diffusion and broth microdilution. spa- and Staphylococcal Cassette Chromosome mec (SCCmec) typing were performed; with multi-locus sequence typing conducted on isolates representing major genotypes. Resistance to moxifloxacin, levofloxacin and ciprofloxacin were 69%, 78% and 96%, respectively. spa type t037 (57%) was commonest, followed by t127 (12.5%), t267 (8%) and t688 (6%). SCCmec III predominated (57%), all of these were moxifloxacin resistant and 97.6% t037 (ST241). SCCmec IV, IV E and V represented 15%, 7% and 11% of the isolates, respectively, 79% of these were moxifloxacin susceptible and of different spa types. t127 (ST-1) was associated with SCCmec V in 56% of the isolates, mostly moxifloxacin susceptible. Moxifloxacin resistance was high, most resistant isolates belonged to t037 and SCCmec III, suggesting local dissemination and antibiotic pressure. We recommend caution in treating MRSA infections with moxifloxacin.

Staphylococcal cassette chromosome mec elements from Staphylococcus intermedius group (SIG) isolates from dogs in a center for veterinary diagnostics in Brazil

ABSTRACT: Methicillin resistance in the Staphylococcus intermedius group (SIG) has emerged in small animal practice. Methicillin-resistant SIG (MRSIG) members have been implicated as causes of infections in both companion animals and humans. Staphylococcal cassette chromosome mec (SCCmec) elements carry the mecA/C genes, which encode for the transpeptidase PBP2a (PBP2’) responsible for β-lactam antibiotic resistance in staphylococci. This study examined the SCCmec types of MRSIG isolates from different clinical specimens of dogs that exhibited methicillin MIC ≥ 0.5 μg/mL by an automated identification and susceptibility system in a Center for Veterinary Diagnostics in São Paulo, Brazil. Susceptibility to methicillin was determined by broth microdilution testing, and Oxoid® M.I.C.Evaluator® strips. PBP2a production was detected using a latex agglutination assay. SCCmec typing was performed according to the International Working Group on the Classification of Staphylococcal Cassette Chromosome Elements (IWG-SCC) guidelines. SCCmec type II (2A), SCCmec type III (3A), composite SCC structures consisting of a class A mec gene complex in addition to multiple ccr gene complexes, and non-typable SCCmec elements were reported in these MRSIG isolates. SCCmec type variants differing from those so far acknowledged by IWG-SCC were found, indicating new rearrangements in the genetic context of mecA in these canine MRSIG isolates.