Study On Antibiotic Resistance And Staphylococcal Chromosomal Cassette Mec Molecular Epidemiology Of Methicillin Resistant Coagulase Negative Staphylococci In Children

Objective To learn the antibiotic resistance status of Methicillin Resistant Coagulase Negative Staphylococcus(MRCNS), and to investigate the distribution and resistant feature of different Staphylococcal Chromosomal Cassette mec(SCCmec) genotypes of Anhui children, so as to guide clinical medication.Methods Resistance phenotype screening were conducted in Coagulase Negative Staphylococcus, which were isolated from clinical strains in Anhui children from 2010 to 2014. MRCNS were identified by the Microscan Walk Away automated system.Mec A gene were detected by Polymerase Chain Reaction(PCR) method in order to collect MRCNS.Minimal Inhibitory Concentrations(MIC) of 16 antibiotics were determined by agar dilution method. Vacomycin-resistant strains were identified by population analysis and the Brain Heart Infusion vancomycin screen agar dilution method recommended by Clinical and Laboratory Standards Institute in 2013.VanA, vanB, vanC1,vanC2/3 gene and SCCmec types were detected by PCR method.Results A total of 148 MRCNS strains were detected by the resistance phenotype screening and the detection of mec A gene. There were Methicillin Resistant Staphylococcus Epidermidis, Methicillin Resistant Staphylococcus hominis, Methicillin Resistant Staphylococcus Haemolyticus,Methicillin Resistant Staphylococcus hominis, Methicillin Resistant Staphylococcus saprophyticus, Methicillin Resistant Staphylococcus simulans,Methicillin Resistant Staphylococcus sciuri, Methicillin Resistant Staphylococcus Xylosus, Methicillin Resistant Staphylococcus warneri, Methicillin Resistant Staphylococcus auricularis, Methicillin Resistant Staphylococcus capitis, and the proportion of them was 44.59%(66/148), 19.59%(29/148), 25.68%(38/148), 2.70%(4/148), 2.03%(3/148), 2.03%(3/148), 1.35%(2/148), 0.68%(1/148), 0.68%(1/148), 0.68%(1/148),respectively.The analysis of antibiotic resistance showed the antimicrobial resistant rate of MRCNS to penicillin, cefoperazone, cefotaxime, ceftriaxone, imipenem and meropenem were all 100%, to azithromycin, erythromycin, ciprofloxacin, clindamycin,levofloxaci, gentamicin, levofloxacin, teicoplanin, chloramphenicol, vancomycin was97.98%, 92.57%, 83.78%, 79.05%, 35.81%, 43.24%, 24.32%, 2.03%, 8.78% and 0.68%,respectively.There was one heterogeneous vancomycin-resistant strain, which was resistant to both vancomycin and teicoplanin(with MIC 32 mg/L and 64 mg/L), but sensitive to rifampincin and levofloxacin. No van A, van B, van C1 or van C2/3 gene was detected from heterogeneous vancomycin-resistant strain by PCR.I to V SCCmec genotypes were detected from 148 MRCNS strains, the major SCCmec type was SCCmec type III, which was followed by hybrid type. Three subtypes of SCCmec type IV were identified, including IVa, IVc and IVd.The resistance rates of all SCCmec genotypes of MRCNS to penicillin,cefoperazone,cefotaxime,ceftriaxone,imipenem,meropenem,erythromycin, azithromycin,ciprofloxacin, clindamycin were high, to levofloxacin, rifampincin, gentamicin were relatively low. No chloramphenicol resistant strain was found in the I,II,IV and V SCCmec genotypes of MRCNS.Conclusion The MRCNS strains of Anhui children showed multiple resistance to antibiotics. It should be on alert that heterogeneous vancomycin-resistant strain was appeared.There were several different SCCmec types among several kinds MRCNS, SCCmec III genotypes was the major epidemic isolates.There was no significant correlation between the different resistance rates of non-β-lactamase antibiotics and SCCmec genotypes in MRCNS.