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Objective To study antimicrobial resistance and genotyping of methicillin-resistant Staphylococcus au-reus(MRSA). Methods A total of 967 no-repetitive strains of Staphylococcus aureus(S.aureus)isolated from a hospital between January 2014 and November 2015 were collected,antimicrobial susceptibility testing,mecA gene,and Panton-Valentine leukocidin gene(PVL gene)were detected;staphylococcal cassette chromosome mec(SCCmec)typing,multilocus sequence typing(MLST),S.aureus protein A(spa)gene typing,and S.aureus ac-cessory gene regulator(agr)typing were performed with multiplex polymerase chain reaction. Results Of 967 strains of S.aureus,210(21.72%)were MRSA;detection rate of MRSA from sputum specimen was higher than that of skin and soft tissue specimen(68.09% vs 1 1.83% ,P<0.05);vancomycin- and linezolid-resistant S.aureus strains were not found,susceptibility rates of MRSA to gentamicin,tetracycline,erythromycin,clindamycin,levo-floxacin,ciprofloxacin,moxifloxacin,nitrofurantoin,and rifampicin were all lower than those of methicillin-sensi-tive Staphylococcus aureus(MSSA),differences were all statistically significant(all P<0.05);antimicrobial sus-ceptibility rate of MRSA to compound sulfamethoxazole was higher than MSSA,difference was significant(P<0.05). Susceptibility rates of MRSA isolated from skin and soft tissue to gentamicin,levofloxacin,ciprofloxacin,moxifloxacin,and rifampicin were 86.90% -95.24%,while MRSA isolated from sputum were only 1.56% -15.63%.Of 967 strains of S.aureus,210 harbored mecA gene,10 harbored PVL gene,8(3.81%)of 210 MRSA strains weren't typed. The main types of MLST,SCCmec,spa,and agr were ST 239(n= 177 strains),type Ⅲ(n= 177 strains),t 030(n= 177 strains),and typeⅠ(n= 196 strains)respectively.Conclusion The main epidemic clone of MRSA strain in this hospital is ST239-MRSA-SCCmec III-t030,antimicrobial resistance is serious,monitoring on drug-resistant strains in hospital should be strengthened.
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Objective To investigate the prevalence, accessory gene regulator (agr) and staphylococcal cassette chromosome mec (SCCmec, only for methicillin resistantS. aureus, MRSA) types of theS. aureus strains carrying toxic shock syndrome toxin-1 (tst) and/or panton-valentine leukocidin (pvl) genes.Methods Nine hundred and sixteen isolates ofS. aureus were collected from seven hospitals in Shanghai and Zhejiang Province and subjected to detection oftst,pvl,mecA andmecC genes by polymerase chain reaction (PCR). Theagr and SCCmec (only for MRSA) types were determined in thetst orpvl gene positive isolates.Results Of the 916 isolates, 208 carriedtst gene (22.7%), 35 harboredpvl gene (3.8%), and 665 weremecA positive (MRSA). No isolate was mecC positive. Out of the 665 MRSA isolates, 198 hosted thetst gene (29.8%). The most commonagr and SCCmec types were agr 2 (97.0%) and SCCmec II (94.4%), respectively. For thepvl gene, only 14 isolates were positive (2.1%). Theagr 1 (85.7%), SCCmecIII (42.9%) and SCCmec IVa (28.6%) were the most commonagr type and SCCmec type. In the 251 methicillin-sensitiveS. aureus (MSSA) isolates, 10 carriedtst gene (4.0%) and 21 carriedpvl gene (8.4%). The prevalence oftst gene in MRSA was higher than that in MSSA, while the prevalence ofpvlgene was just the opposite. However, the prevalence ofpvlgene in MRSA isolates from Zhejiang Province was higher than that in the MRSA isolates from Shanghai (P severeS. aureus infections.
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Background & objectives: The two major genotypic markers that distinguish community acquired (CA) from hospital acquired (HA) methicillin resistant staphylococcus aureus (MRSA) isolates are the architecture of mobile genetic element (SCCmec type) and presence of panton valentine leukocidin (PVL) toxin. This study was conducted to determine the molecular characteristics of CA- and HA- MRSA and methicillin sensitive S. aureus (MSSA) isolates in Sikkim. Methods: A total of 150 clinical isolates of S. aureus isolated from various clinical specimens were subjected to duplex (mec-A and pvl gene) and multiplex (SCCmec typing) PCR. Results: of the 150 isolates, 53 (35.33%) and 66 (44%) were positive for mec-A (MRSA) and pvl genes, respectively. Thirty eight (25.33%) met the definition of CA-MRSA and 15 (10%) of HA-MRSA and the remaining 63 (42%) and 34 (22.66%) as CA- and HA-MSSA, respectively. No significant difference was seen in the distribution of PVL toxin in MRSA and MSSA isolates, but it was significantly (P<0.001) high in overall MRSA isolates than in MSSA. The majority of the MRSA isolates showed a double amplification band of SCCmec type III plus V (54.71%), and only a fewer isolates were amplified by single DNA fragments of type I (1.88%), III (3.77%), IVa (1.88%) and V (11.32%). SCCmec types I, III, IVa, were found only in HA-MRSA isolates, whereas type V in both the CA- and HA-MRSA. AST pattern showed that 18.42 per cent (7/38) and 46.66 per cent (7/15) were multidrug resistant (MDR)-CA-MRSA and MDR-HA-MRSA, respectively. Interpretation & conclusions: The present results show that SCCmec type V MRSA has been on the rise, and genotypic markers such as pvl gene detection used for the differentiation of these clinically distinct isolates of MRSA may not be reliable.
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In order to obtain adequate information for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections, it is crucial to identify trends in epidemiological and antimicrobial resistance patterns of local S. aureus strains. Community and hospital acquired S. aureus isolates (n = 202) were characterized using staphylococcal cassette chromosome mec (SCCmec) typing, pulse field gel electrophoresis (PFGE) analysis, spa typing and minimal inhibitory concentration (MIC) determination. The prevalence of the Panton-Valentine leukocidine (pvl) and several antibiotic resistance genes among the isolates were also detected by PCR. All of the S. aureus isolates were susceptible to vancomycin, daptomycin and linezolid. Three hospital isolates were resistant to teicoplanin while 14 showed intermediate resistance to teicoplanin. The resistance patterns of community-acquired MRSA (CA-MRSA) isolates to other antimicrobials were similar to those of hospital-acquired MRSA (HA-MRSA) isolates except for clindamycin and gentamicin. There was excellent correlation between phenotypes and genotypes in the determination of S. aureus resistance to erythromycin, gentamicin, and tetracycline. The SCCmec type II and SCCmec type IV were the predominant types detected in hospital and community isolates, respectively. The most frequently encountered spa types were t002 and t030 both in HA-and CA-MRSA isolates. Pulsotype A was the most predominant pulsotype identified among the isolates tested, followed by pulsotype B. Seventy-two hospital isolates (19 HA-MRSA and 53 HA-MSSA) and 10 CA-MRSA were positive for the pvl gene. This study shows that the combination of susceptibility testing and various molecular methods has provided useful information on the antibiotic resistance and molecular diversity of S. aureus in a specific region of China. The high proportion of pvl positive MSSA and MRSA isolates observed in this study indicates that adequate measures are needed to curtail the spread of those MRSA and MSSA clones prevailing both in hospital and the community.
Subject(s)
Humans , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Staphylococcal Infections/microbiology , Staphylococcus aureus/genetics , Bacterial Typing Techniques , Bacterial Proteins/genetics , China/epidemiology , Community-Acquired Infections/microbiology , Cross Infection/microbiology , DNA, Bacterial/genetics , Electrophoresis, Gel, Pulsed-Field , Methicillin-Resistant Staphylococcus aureus/genetics , Staphylococcus aureus/drug effectsABSTRACT
Background: Molecular characterization of staphylococcal cassette chromosome mec (SCCmec) types of methicillin-resistant Staphylococcus aureus (MRSA) is very essential for studying the epidemiology of MRSA. Objectives: This study reports two multiplex PCR for molecular typing of MRSA collected from Jeddah, Kingdom of Saudi Arabia. Materials and Methods: A total of 101 clinical isolates of strains were collected from major hospital laboratories and public health centres, Jeddah, Kingdom of Saudi Arabia during the period from August 2009 to May 2011. All the strains were tested phenotypically by conventional methods and genotypically by a novel multiplex PCR targeting at the same time S. aureus 16S rRNA, Panton - valentine leucocidin (PVL) and mecA resistance genes. All the strains were tested also by multiplex PCR for typing of SCC mec types. Results: All the 101 strains previously identified phenotypically as S. aureus with bacteriological examination were positive for amplification of 756 base pair fragments specific for 16S rRNA of S. aureus. Moreover, all the strains were positive for amplification of 1339 base pair fragments specific for mecA gene, while only 38 strains (37.6%) showed positive amplification of 433 base pair fragments specific for PVL gene. The most predominant SCC mec type among the examined isolates is type V 43 (42.5) followed by SCCmec type III 39 (38.6%). Conclusion: The newly modified multiplex PCR is rapid and sensitive method for detection of MRSA. Moreover, the most predominant SCC mec type among the examined isolates from Jeddah, King Saudi Arabia is type V (42.5%), followed by Type III (38.6%).