Clinical significance and staphylococcal cassette chromosome mec (SCCmec) characterization of coagulase-negative staphylococci isolated from blood cultures (original) (raw)
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The Journal of Infectious Diseases, 2010
Background. Data on community spread of methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are scarce. We assessed their potential role as a reservoir of staphylococcal cassette chromosome mec (SCCmec) IVa, the leading SCCmec subtype in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Methods. Nasal carriage of MR-CoNS was prospectively investigated in 291 adults at hospital admission. MR-CoNS were characterized by SCCmec typing, long-range polymerase chain reaction (PCR) for SCCmec IV, and multiple-locus variable-number tandem repeat analysis (MLVA) for Staphylococcus epidermidis (MRSE) strains. Three SCCmec IVa elements were fully sequenced. Results. The carriage rate of MR-CoNS was 19.2% (25.9% and 16.5% in patients with and patients without previous exposure to the health care system, respectively; P p .09). MR-CoNS strains (n p 83, including 58 MRSE strains with highly heterogeneous MLVA patterns) carried SCCmec type IVa (n p 9, all MRSE), other SCCmec IV subtypes (n p 9, including 7 MRSE), other SCCmec types (n p 15), and nontypeable SCCmec (n p 50). Longrange PCR indicated structural homology between SCCmec IV in MRSE and that in MRSA. Complete sequences of SCCmec IVa from 3 MRSE strains were highly homologous to those available for CA-MRSA, including major clones USA300 and USA400. Conclusions. MR-CoNS are probably disseminated in the community, notably in subjects without previous exposure to the health care system. MRSE, the most prevalent species, may act as a reservoir of SCCmec IVa for CA-MRSA. Methicillin-resistant Staphylococcus aureus (MRSA) has been almost exclusively a health care-associated path
Infection, 2008
Background: The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) has dramatically changed over the last decade by the emergence of community-associated MRSA (CA-MRSA). Recent studies indicate that these strains have already spread to hospitals. To evaluate if SCCmec type IV and Panton-Valentine leukocidin (PVL) are unambiguous markers of CA-MRSA, we analyzed 77 sporadic MRSA strains isolated, in our low MRSA incidence university hospital, from inpatients between 2000 and 2004. Methods: MRSA strains were analyzed by staphylococcal cassette chromosome mec (SCCmec) typing, PCR for PVL genes and pulsed-field gel electrophoresis (PFGE). MRSA was classified in HA-MRSA or CA-MRSA according to Centers for Disease Control and Prevention (CDC) criteria. Antimicrobial susceptibility testing was performed using microbroth dilution method following CLSI recommendations. Results: Among 77 sporadic single-patient strains, SCCmec types I-IV and four subtypes were identified. Type IV/IVA was most common (42.9%).The distribution of SCCmec types changed over the years. Type IV/IVA strains increased from 33.3% in 2000 to 57.9% in 2004. Type IV strains were resistant to ciprofloxacin in 81.8%, and in 9.1% to tobramycin while type IVA strains were 100% resistant to both antimicrobials. In contrast, non-type IV/IVA strains were resistant to ciprofloxacin in 86.4%, and in 75.0% to tobramycin. Only one strain was PVL positive and harbored SCCmec type III variant. By PFGE analysis, the 33 SCCmec type IV/IVA strains comprised 12 distinct genotypes. 36.4% of 11 CA-MRSA and 43.9% of 66 HA-MRSA harbored SCCmec type IV/IVA. Conclusion: Type IV/IVA has become the most common SCCmec type in inpatients of our university hospital. The SCCmec type IV/IVA is present in both CA-MRSA and HA-MRSA limiting its use as a marker for CA-MRSA.
Diagnostic Microbiology and Infectious Disease, 2009
Change in epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) was observed because of the emergence of infections by non-multiresistant MRSA (nMRSA) in our hospital in Rio de Janeiro, Brazil. Clinical characterization and molecular analysis of 20 nMRSA isolates recovered from 17 patients, between February 2005 and March 2006, were performed. The analysis included SCCmec (staphylococcal cassette chromosome mec), pulsed field gel electrophoresis (PFGE), multilocus restriction fragment, and multilocus sequence typing. MICs for oxacillin and vancomycin and presence of Panton-Valentine leukocidin (PVL) genes were also investigated. All but 1 of the 20 isolates presented SCCmec type IV. PFGE clustered all isolates into 9 genotypes. MIC ≤16 μg/mL to oxacillin was found for 65% of the isolates, whereas 80% exhibited MIC of 2 μg/mL for vancomycin. PVL-encoding genes were observed in 3 isolates. Polyclonal presence of nMRSA SCCmec IV was observed in our institution, including community and health care-associated isolates, which belonged to the sequence types (STs) 1 (clonal complex [CC1]), ST5 (CC5), ST8 and ST72 (CC8), ST97 (CC97), and 2 ST singletons (SLV5 and SLV30).
American Journal of Infectious Diseases, 2008
To evaluate different methods for the identification of methicillin-resistant Staphylococci and their reliability, 112 Staphylococcal isolates (32 Staphylococcus aureus isolates and 80 coagulase negative Staphylococci isolates "CoNS") were collected from 118 nasal swab cultures and were subjected to three methods to detect oxacillin susceptibility of the isolates. The three methods were oxacillin disk diffusion method; the Epsilometer-test (E-test) and polymerase chain reaction (PCR). For the S. aureus strains, the E-test and the PCR methods showed discrepant results in two isolates (6.25%); that showed susceptible patterns with the E-test, but were resistant by the disk diffusion method. Both isolates were negative for the presence of mecA gene. Seven (8.75%) out of the 80 CoNS isolates showed conflicting results where four isolates showed resistance with the disk diffusion and the E-test methods, and had negative mecA gene by PCR. Three of the 7 CoNS with the conflicting results showed a susceptible pattern to oxacillin by the E-test method, while the PCR method showed the presence of mecA gene. We concluded that combination of molecular and conventional methods should be used to assess methicillin resistance of Staphylococci in clinical practices.
International Journal of Antimicrobial Agents, 2012
Molecular identification methods based on the staphylococcal cassette chromosome mec (SCCmec) genotype are more reliable than clinical risk factors and demographic data for differentiating communityacquired and healthcare-associated (HCA) meticillin-resistant Staphylococcus aureus (MRSA). However, patients with community-onset (CO) MRSA infections, defined as a culture-positive sample obtained <48 h after admission and from patients with HCA risk factors, have been infrequently studied. This study compared the clinical profiles of different SCCmec genotypes in this group of patients. From 2004 to 2008, the clinical profiles of 122 non-repetitive patients with CO-MRSA infections at a tertiary medical centre in Taiwan were retrospectively recorded and the molecular characteristics of the isolates were examined. The proportion of SCCmec IV/V genotypes increased from 9.5% to 35.3% from 2004 to 2008. There were no differences in demographic data, underlying diseases, invasive procedures or outcomes between the SCCmec II/III and IV/V groups, except that patients with SCCmec II/III genotypes tended to have more HCA risk factors (3.1 vs. 2.4; P = 0.008). Multivariate logistic regression analysis revealed that having at least four HCA risk factors was independently associated with SCCmec II/III. The sensitivity of recovering SCCmec IV/V genotypes from patients with less than four HCA risk factors was 89.3%. This study revealed the emergence of SCCmec IV/V genotypes in CO-MRSA infections. Although the clinical characteristic boundaries between SCCmec II/III and IV/V diminished, having at least four HCA risk factors made the presence of SCCmec IV/V genotypes less likely in patients with CO-MRSA infections.
Open Journal of Medical Microbiology, 2015
MRSA is able to generate a modified variety of penicillin binding protein named as PBP2a instead of PBP which makes it resistant against penicillin and methicillin. Production of PBP2a is due to the presence of a gene on Staphylococcal cassette chromosome or SCC termed as "mec-A gene". SCC is a mobile genetic element carrying many resistance genes. It is because of current antibiotic selection pressure that by now there are eight types (I-VIII) of SCCmec. This research has been designed to determine frequency of SCCmec type IV and V in clinical isolates of MRSA. A total of 70 presumptive MRSA isolates collected from a tertiary care hospital of Lahore were cultured on blood agar, incubated overnight at 37˚C aerobically. Next day, they were examined for cultural characteristics, colonial morphology, gram stain, and biochemical profile. Confirmation of MRSA was done by phenotypic disk diffusion method according to (CLSI) 2013 guidelines. mecA gene was also detected at molecular level. Molecular identification of SCCmec type IV and V was done by Nested PCR strategy. A total of 50 isolates were confirmed to be MRSA Molecular detection of SCCmec type IV and V revealed that 11 isolates (22%) possess SCCmec type IV and only 2 isolate (4%) carries SCCmec type V. It is obvious from results that SCCmec type IV and V are present in our population too. Larger study (with larger sample size) might be undertaken to find out actual emergence of SCCmec type IV and V in our population.
Introduction: Methicillin resistant Staphylococcus aureus (MRSA) is a versatile pathogen capable of causing multitude of human diseases. It is one of the most important nosocomial pathogen that implicated in community and healthcare associated infections. Therefore, this study aims to characterize different SCCmec elements found in MRSA isolates. Moreover, molecular typing was performed to investigate the genetic relatedness among MRSA isolates. Methods: Phenotypic identification of MRSA was done by disc diffusion method. The MRSA isolates were typed based on the SCCmec, coa and agr genes. Phenotypic characterization included the detection of biofilm, lipase, protease, lecithinase, staphylokinase and hemagglutination. Also, hla, hlb, hlg, hld, tsst-1, psm-mec and mecI genes were detected genotypically. The correlation between the molecular types identified and the profile of virulence factors, clinical and geographical sources was determined for all isolates. Results: Eighty five isolates were identified as MRSA. Eight types of SCCmec elements were detected among these isolates. Type V was the most observed type (56.47%). Regarding the correlation between SCCmec types and virulence factors, type V SCCmec exhibited a significant association with biofilm (p < 0.0001), staphylokinase (p = 0.0495) and tsst-1 (p = 0.0498). Molecular typing of coa gave an insight to the presence of specific types in specific hospital wards. Based on agr typing, agr I was the highest prevalent type in MRSA isolates (54.11%). Conclusion: There is an increase of MRSA infections particularly the community acquired with high variability in the distribution of virulence factors among different SCCmec types. The association between type III and V SCCmec with certain hospitals may be an evidence of nosocomial infection among these hospitals.
Intisari Sains Medis
Background: Methicillin-Resistant Staphylococcus aureus (MRSA) is a big challenge for health services worldwide which causes infections both in healthcare and community. Healthcare-associated MRSA (HA-MRSA) strains are shown to be resistant to beta-lactam antibiotics and several non-beta lactam antibiotics. At the same time, the community-associated MRSA (CA-MRSA) tends to be resistant to beta-lactam antibiotics. MRSA carried staphylococcal cassette chromosome (SCCmec) types I, II, III, IV, and V. SCCmec types I, II, and III were predominantly found in HA-MRSA strain while SCCmec types IV and V predominantly found in CA-MRSA strains. Furthermore, the panton valentine leukocidine (pvl) gene is commonly found in CA-MRSA strains. Therefore, this study aimed to determine the prevalence of SCCmec types I, II, III, and pvl gene in MRSA isolated from clinical specimens in Sanglah General Hospital. Methods: This study was a cross-sectional descriptive study. MRSA was isolated from clinical...
Open Journal of Medical Microbiology, 2015
MRSA is able to generate a modified variety of penicillin binding protein named as PBP2a instead of PBP which makes it resistant against penicillin and methicillin. Production of PBP2a is due to the presence of a gene on Staphylococcal cassette chromosome or SCC termed as "mec-A gene". SCC is a mobile genetic element carrying many resistance genes. It is because of current antibiotic selection pressure that by now there are eight types (I-VIII) of SCCmec. This research has been designed to determine frequency of SCCmec type IV and V in clinical isolates of MRSA. A total of 70 presumptive MRSA isolates collected from a tertiary care hospital of Lahore were cultured on blood agar, incubated overnight at 37˚C aerobically. Next day, they were examined for cultural characteristics, colonial morphology, gram stain, and biochemical profile. Confirmation of MRSA was done by phenotypic disk diffusion method according to (CLSI) 2013 guidelines. mecA gene was also detected at molecular level. Molecular identification of SCCmec type IV and V was done by Nested PCR strategy. A total of 50 isolates were confirmed to be MRSA Molecular detection of SCCmec type IV and V revealed that 11 isolates (22%) possess SCCmec type IV and only 2 isolate (4%) carries SCCmec type V. It is obvious from results that SCCmec type IV and V are present in our population too. Larger study (with larger sample size) might be undertaken to find out actual emergence of SCCmec type IV and V in our population.