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Objective: Staphylococcus aureus is an important pathogen causing infections in the hospital, in recent years, increased year by year because of its rate of clinical isolates, resistance is growing, and the focus has become a global concern. This paper aims to study hospital infection clinical isolates of Staphylococcus aureus isolated from children and antibiotic drug resistance testing and analysis of drug resistance spectrum, provide the basis for rational clinical use of antibiotics and resistance by mecA gene detection and SCCmec genotyping A mechanism of resistance to methicillin staphylococcus discuss in depth understanding of the clinical epidemiological characteristics of staphylococcal infections, provide countermeasures for the development of drug-resistant strains of clinical prediction trend, anti-infection treatment, and prevention of an outbreak of methicillin-resistant staphylococcus resistant and basis. Methods: (1) 138 isolated from the Tianjin Children's Hospital patients with nosocomial infections Staphylococcus strain identification and analysis of clinical data. (2) the application broth microdilution susceptibility board detection aureus resistance rates of 16 kinds of commonly used antibiotics, analyze the resistance spectrum; vancomycin screened experimental screening out potential VISA, vancomycin E experiments validate . (3) Application the Nitrocefin Flat detection activity of β-lactam, and is detected using the same method after induction by 0.05μg/ml oxacillin Staphylococcus activity of β-lactam. (4) using PCR to detect Staphylococcus mecA gene carrying status, verify the MRS on the genetic level. (5) mecA-positive Staphylococcus aureus strains with two classic multiplex PCR SCCmec genotyping quickly and easily on the basis of molecular biology of multidrug-resistant generated. Results: (1) 138 aureus was identified, the separation of Staphylococcus aureus (SA) strains and 65 coagulase-negative staphylococci (CNS) 73 strains, SA mainly isolated CNS mainly isolated from sputum samples from respiratory blood samples, both methicillin-resistant rate were 10.8%, 80.8%, respectively. (2) CNS oxacillin, erythromycin, gentamicin, ampicillin / sulbactam, cephradine, ciprofloxacin, cefepime, amlodipine penicillin and other antibiotic resistant rates higher than the SA (P <0.05), a statistically significant difference. Both Apart from sensitive to vancomycin, other commonly used antibiotics have varying degrees of resistance. MRCNS cephradine, ceftriaxone, the amlodipine penicillin, ampicillin / sulbactam, erythromycin resistance rate is higher than the MSCNS (P <0.05), and multidrug-resistant characteristics. Vancomycin-plate screening test and E test confirmed vancomycin-resistant strains has yet to appear. (3) 0.05μg/ml oxacillin induction, SA, β-lactamase detection rate increased from 50.8% to 89.2%, CNS β-lactamase detection rate increased to 90.4% from 61.6% clinical laboratories can be applied in the detection of β-lactamase oxacillin induced in order to reduce the generation of false negative. (4) of mecA gene detection rate of 38%. In 7 phenotype MRSA, five confirmed with of mecA; in 59 phenotypic MRCNS, 46 (78%) were mecA positive, 13 of mecA is not detected (22% false positives); tables by in the the type packet of MSSA, no measured mecA positive strains; the 14 phenotype MSCNS only one mecA positive (7% false negative). (5) 5 mecA-positive Staphylococcus aureus detect the SCCmec I, Ⅲ, IVa type one, two failed genotyping; 47 (64.4%) mecA-positive coagulase-negative staphylococci, divided the SCCmec Ⅰ type and type Ⅰ A 6 Zhu Ⅲ type and type Ⅲ B 10 Zhu, of type Ⅳ 9 Zhu, Ⅴ type 3 Zhu and variation of new SCCmec class Ⅰ type 4 Zhu, class type Ⅰ A 5 Zhu, there are still 10 Zhu failed to sub- type. Conclusion: Hospital infection rate of the multidrug-resistant coagulase-negative staphylococci and mecA carrying rate in Staphylococcus aureus, needs to cause clinical enough attention, the hospital has not yet found a vancomycin-resistant strain or intermediate resistant strains; conduct oxacillin-induced β-lactamase detection can be applied to reduce the generation of false negative; judge the MRSA or MRCNS a false positive may be greater than the false negative may need mecA genetic testing to determine the MRS phenotype; half above coagulase-negative staphylococci SCCmec available existing multiplex PCR genotyping, but two new SCCmec suspected type I mutant, tentatively scheduled for the class I type and class type Ⅰ A, can be used as a further study MRS resistance genetic origin and entry point mutation.
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