Detection of heterogeneous vancomycin-intermediate Staphylococcus aureus: A preliminary report from south India

Background & objectives: Although there are reports of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) across the globe, there is a lack of reliable data on hVISA in India. The present study was undertaken to determine the rate of hVISA among the methicillin-resistant Staphylococcus aureus (MRSA) isolates, and to compare the brain heart infusion agar with vancomycin 4 ?g/ml (BHIV4) method with population analysis profile-area under the curve (PAP-AUC) method for the detection of hVISA and to study the distribution of mobile genetic element that carries methicillin-resistance gene SCCmec (Staphylococcal cassette chromosome mec) types among these isolates. Methods: BHIV4 and PAP-AUC methods were employed to detect hVISA among 500 clinical isolates of MRSA. SCCmec typing of these isolates was performed by multiplex polymerase chain reaction. The clinical presentation, treatment with vancomycin and outcome was documented for patients with hVISA. Results: The rate of hVISA was 12.4 per cent by PAP-AUC method. Sensitivity, specificity, PPV, NPV and kappa agreement of BHIV4 with PAP-AUC was 58.06, 93.15, 54.55, 94.01 per cent and 0.498, respectively. The isolation of hVISA was significantly (P<0.01) higher in patients admitted to intensive care units and wards than in patients attending the outpatient departments. Only 38 per cent of the patients received vancomycin as therapy. Majority of the hVISA isolates carried SCCmec type V or IV. Interpretation & conclusions: The rate of hVISA isolation in our study was 12.4 per cent. The sensitivity of the BHIV4 screening test was low, and was in moderate agreement with PAP-AUC test. SCCmec type V was the predominant type seen in half of the isolates. More studies need to be done in different parts of the country on a large number of isolates to confirm our findings.

Homologous SCCmec elements in clinical isolates of methicillin-resistant Staphylococcus epidermidis carrying psm-mec / 西安交通大学学报(医学版)

Objective To investigate SCCmec types in clinical isolates of methicillin-resistant Staphylococcus epidermidis (MRSE) carrying psm-mec.Methods We collected 165 strains of Staphylococcus epidermidis identified by automated microbiological identification system and screened MRSE by PCR amplification of esp and mecA gene.Strains with psm-mec were identified by amplification of psm-mec,fudoh and p221 DNA fragment;mec,ccr and SCCmec typing was conducted by multiplex PCR assay.Results Among 138 strains of MRSE,29 strains were identified as MRSE with psm-mec,and the carrying rate was 17.58%.Results of mec and ccr typing by multiple PCR showed that MRSE with psm-mec carried Class A mec,but the ccr type had obvious diversity.Results of SCCmec typing showed that all strains with psm-mec belonged to type Ⅱ and/or Ⅲ SCCmec.Conclusion Clinical isolates of MRSE with psm-mec carry homologous type Ⅱ and/or Ⅲ SCCmec harboring Class A mec.

Prevalence and Molecular Characteristics of Methicillin-resistant Staphylococcus aureus Isolates in a Neonatal Intensive Care Unit

The molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from neonates in a neonatal intensive care unit (NICU) were investigated by multilocus sequence typing (MLST), staphylocoagulase (SC) genotyping, staphylococcal cassette chromosome mec (SCCmec) typing, accessory gene regulator (agr) typing, and the presence of Panton-Valentine leukocidin (PVL). Among the 44 S. aureus isolates from nares in neonates between March and June 2014 at hospital in Busan, 27 (61.4%) were MRSA and 17 (38.6%) were methicillin-susceptible S. aureus (MSSA). The most prevalent clone in MRSA isolates was ST72-SC type Vb-SCCmec IV-agr I (n=26) and the remaining one was ST89-SC type I-SCCmec II-agr II. In MSSA isolates, the prevalent clone was ST121-SC type Va-agr IV (n=13), followed by ST72-SC type Vb-agr I (n=2), ST8-SC type III-agr I (n=1) and ST15-SC type X-agr II (n=1). All isolates did not possess the PVL. The data showed that the neonates in NICU carried high prevalence of ST72 MRSA and remarkably different clones with SC diversity between MRSA and MSSA isolates.

Diversity of SCCmec type diversity in clinically isolated methicillin-resistant Staphylococcus epidermidis / 国际检验医学杂志

Objective To investigate the SCCmec types of clinically isolated methicillin‐resistant Staphylococcus epidermidis (M RSE) .Methods Eighty‐four strains of clinically isolated Staphylococcus epidermidis identified by the fully automatic microbio‐logical identification system were collected and performed the MRSE identification by PCR for amplifying esp and mecA genes and SCCmec typing .Its distribution characteristics were analyzed .Results Esp gene was amplified in 84 strains and the detection rate of mecA was 76 .19% (64/84) ,in which the MRSE detection rates in blood ,sputum ,urine and wound secretion were 76 .8% , 68 .8% ,100% and 71 .4% respectively .The multiple PCR amplification displayed that among 64 strains of MRSE ,19 strains were SCCmec simple type ,in which 19 strains were SCCmec type Ⅰ and 3 strains were SCCmec type Ⅲ ;42 strains were SCCmec mixed type ,in which 2 strains were SCCmec mixed type Ⅰ and Ⅱ ,14 strains were SCCmec mixed type Ⅰ and Ⅲ ,12 strains were SCCmec mixed type Ⅰ ,Ⅱ and Ⅲ ,5 strains were SCCmec mixed type Ⅱ and Ⅲ ,a strains were and SCCmec mixed type Ⅲ and Ⅳ .Conclu‐sion The SCCmec type in clinically isolated MRSE shows obvious diversity and its majority is SCCmec mixed type .

Molecular Characterization of Community-Associated Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Isolates from Children with Skin Infections in Busan, Korea

The prevalence and molecular characteristics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and methicillin-susceptible S. aureus (CA-MSSA) from children with skin infection were investigated by staphylocoagulase (SC) typing, multilocus sequence typing (MLST), SCCmec typing and virulent toxins, including Panton-Valentine leucocidin (PVL), and exfoliative toxins (ET). Among 69 cases of CA-S. aureus for a 3 month period from March to June, 2014 at hospital in Busan, 28 (40.6%) were MRSA and 41 (59.4%) were MSSA. Of the 28 CA-MRSA isolates, two major clones were identified as SC type Vb-ST72-SCCmec type IV (53.6%) and SC type l-ST89-SCCmec type II variant (42.8%), and the remaining one (3.6%) was SC type lll-ST8-SCCmec type IV. In CA-MSSA, the prevalent clone was SC type Vb-ST72 (29.3%), followed by SC type Vb-ST188 (21.9%), SC type Va-ST121 (19.5%) and SC type lV-ST30 (9.6%). None was positive for PVL gene, and all of the SC type l-ST89-SCCmec type II variant clones were ETB gene positive. The data suggest that there are significant clonal relatedness with specific SC types, and genetic diversities in both community strains isolated from children with skin infections.

Genetic characterization of methicillin-resistant Staphylococcus aureus from humans and animals within the community / 대한수의학회지

Methicillin-resistant Staphylococcus (S.) aureus (MRSA) is one of the most important nosocomial pathogens worldwide and the emergence of this strain has become a major clinical problem. In this study, we investigated the prevalence of MRSA and their genetic characteristics in 69 S. aureus isolated from humans and animals. In human isolates, higher antimicrobial resistance rates were observed against penicillin (80.6%), followed by erythromycin (11.9%) and tetracycline (9.0%). All of them were susceptible to clindamycin, enrofloxacin, novobiocin, pirlimycin, trimethoprim/sulfamethoxazole and vancomycin. The resistance patterns in animal isolates were similar to those of human isolates. Two (2.9%) MRSA strains were isolated from human (n = 1) and animal (n = 1), and these isolates were confirmed as carrying the mecA gene. One isolate originating from human was resistant to 7 drugs and the other isolate derived from animal was resistant to 11 drugs. Staphylococcal cassette chromosome mec (SCCmec) variant IIIB was identified in animal isolate but SCCmec type of an isolate from human was not exactly determined. Two MRSA isolates showed unrelated PFGE pattern between them. Our results indicated although the frequency of MRSA isolates from humans and animals was low, a continuous surveillance and monitoring should be called for to prevent the contamination and spread of MRSA in the community. To our knowledge, this is the first time that SCCmec type variant IIIB was detected from animals in Korea.

Correlation between Sau1 Restriction and Modification Complex Type and Coagulase Serotype or SCCmec Type of Staphylococcus aureus

Staphylococcus aureus coagulase serotype I to VIII isolated from clinical samples could be classified into two groups, methicillin-sensitive S. aurues (MSSA) and methicilln-resistant S. aurues (MRSA), by antibiotics susceptibility and existence of mecA which is a gene related with methicillin resistance. Coagulase serotype I, VI, and VIII were MSSA which showed different antimicrobial susceptibility. Coagluase serotype II-V and VII were MRSA in which mecA and SCCmec were detected. To analyze Sau1 restriction and modification (R-M) complex types by coagulase type and SCCmec type, sau1hsdR, sau1hsdM and sau1hsdS genes involved in Sau1 R-M complex were detected by PCR, we found five complex types such as M1, R2M2, R2M2, R2M2S1, and R2M2S2. Coagulase serotype I, VI, and VIII of MSSA were M1, R2M2 and R2M2, respectively. SCCmec type II and coagulase serotype II, SCCmec type III and coagulase serotype III, SCCmec type IV and coagulase serotype V, and SCCmec type IV and coagulase serotype IV, VII of MRSA were Sau1 R-M complex type R2M2S1, R2M2, R2M2, and R2M2S2, respectively. Taken together, correlation between Sau1 R-M complex types and coagulase or SCCmec types of S. aureus was found.