ABSTRACT
Objective To investigate the drug resistance situation and Staphylococcal cassette chromosome mec(SCCmec) genotypes of methicillin resistant Staphylococcus aureus (M RSA ) strains isolated from Shang-hai Putuo District People′s Hospital in order to provide a theoretical basis for predicting the trend of drug re-sistant bacterial strains and clinical treatment and prevention of MRSA .Methods Three hundreds and eighty clinically isolated MRSA strains in this hospital were collected from January 2012 to December 2016 .The in vitro drug susceptibility test was performed by adopting the broth microdilution method .The SCCmec geno-types were examined by adopting the multiplex polymerase chain reaction .Results All strains were sensitive to linezolid and vancomycin ,the sensitivity rate was 100 .0％ ;the resistance rates to rifampicin and cotrimox-azole were lower ,which were 5 .0％ and 7 .6％ respectively ;but the strains were highly resistant to erythromy-cin ,levofloxacin and tetracycline ,with the resistance rate of 100 .0％ ,94 .2％ ,93 .4％ and 90 .0％ .The resist-ance rate to penicillin was 100 .0％ .Among 380 strains of MRSA ,there were 281 strains(73 .9％ ) of SCCmecⅡ ,59 strains (15 .5％ ) of SCCmecⅢand 5 strains (1 .3％ ) of SCCmecⅣa ,other 35 strains(9 .2％ ) of MRSA could not be classified .Conclusion M RSA strains isolated in the Shanghai Putuo District People′s Hospital are mainly the type SCCmecⅡ ,w hich has the multi-drug resistant characteristics ,and the drug resistance spec-trum of different SCCmec genotypes is different .
ABSTRACT
Objective To study a nucleic acid extraction method suitable for detecting methicillin‐resistant Staphylococcus aureus (MRSA) by PCR method .Methods Under different incubation conditions ,MRSA was cracked by lysozyme ,lysostaphin or chel‐ex100R resin for obtaining DNA ,then the target gene was detected by using the PCR method .Results DNA was obtained by sim‐ultaneously using lysozyme ,lysostaphin and chelex100R resin solution ,the obtained Ct value was significantly lower than that of the other components of schizolysis solutions when PCR was used to detect mecA gene of obtained DNA .There was no statistically sig‐nificant difference between adopting the 56 ℃ one‐step method and the 37 ℃ and 56 ℃ two‐step method for conducting MRSA schizolysis(P> 0 .05) ,but the steps were simplified .Conclusion Incubating MRSA in solution containing lysozyme ,lysostaphin , chelex100R resin for 30 min at 56 ℃ is the convenient and efficient schizolysis method to extract DNA ,which can be used immedi‐ately for the next step of PCR and lays the foundation for PCR rapid detection of clinical MRSA infection .
ABSTRACT
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.