MRSA Resistant Character And Type Research

The antibiotic is one of the greatest achievements in the medical field, and it plays an extremely important role in the improvement of the human health and guarantee of the life security. However, it is very outstanding at present that antibiotic is abused in domestic and abroad, which results the antibiotic-resistant bacteria to increase sharply. Methicillin-resistant staphylococcus aureus (MRSA) is one of the most important multidrug-resistant bacterium in the hospital. The first MRSA was reported in 1961 in England. Since then, MRSA becomes one of the most significant nosocomial pathogens throughout the world and is capable of causing a wide range of hospital infections. At present a number of different clones of MRSA have arisen in many countries, and there are about 100,000 persons who are infected by MRSA every year in the world, which is reported by Centers for Disease Control and Prevention (CDC), while it also has become increasingly prevalent in community-acquired infections. Because of carrying a variety of toxins, strong infections, MRSA parallels to be the three major infectious diseases with AIDS and viral hepatitis B in the world.In order to understand the infection status caused by MRSA in the Shanxi Provincial People's Hospital (SPPH), the research was done to detect MRSA in 18 samples from the patients in clinic and hospital which was infected by staphylococcus aureus from September 2005 to September 2008 by cefoxitin disc diffusion method, oxacillin disc diffusion method and mecA Genes PCR method. Kerby- Bauer disk diffusion test was used to detect the susceptibility of MRSA to 9 kinds of antibacterial agents. PCR method was used to dectect PVL gene from the genomic DNA of infection strains. RAPD was used to type the chromosome DNA of MRSA strains. Novel multiplex PCR was used to type Staphylococcal chromosomal cassette mec (SCCmec). This study aims to find out MRSA molecular epidemiology, distinguish genotype and prevail trend in SPPH, and to afford method for controlling infection in clinical. The main results of the research were as follows.1. The results of antibiotic resistance and detecting PVLIn this study, PVL gene was not detected from the genomic DNA of 18 samples. The rate of resistance to penicillin, oxacillin, cefoxitin, ciprofloxacin and gentamicin were 100% in 18 MRSA strains; Rate of resistance to clindamycin and red neomycin was 88.9%, and the mid-sensitivity rate of Rifampin was 11.1%, the resistant rate of rifampin was 55.6%.100% MRSA strains were susceptible to Vancomycin. All of 18 MRSA strains were multidrug-resistant bacterium, and the resistant model were 5 kinds of antibiotics agents (22.2%),6 kinds (33.3%),7 kinds (44.5%). The majority (44.5%) of the strains were resistant to penicillin, cephalosporins, linklactams, macrolides, quinolones, aminoglycosides, sha-neomycin. All isolates were resistant to penicillins, cephalosporins, fluoroquinolones and aminoglycosides.2. The SCCmec genotype of MRSABy using multiplex PCR of the 18 MRSA for SCCmec type, we found nine strains (50%) carrying three kinds of new SCCmec type/subtype (Newl～3),6 strains (33.3%) carryingⅢB SCCmec, while 3 strains (16.7%) were not stereotyped strain. MRSA in this region of the SCCmec types were highly polymorphic, and IIIB SCCmec were the local advantage type. RAPD electrophoresis profiles of cluster was analysed by the NTSYS software. The strains were fall into two types A, B, in which type A can be further divided into four subtypes:A1, A2, A3 and A4.The results of MRSA resistance profile typing, SCCmec typing and RAPD typing were not completely consistent, suggesting they didn't have direct correlation.MRSA is one of the most important pathogen in the hospital- and community- acquired. They had the charcteristic of pathogenicity and serious multiple drug resistance, however so far there wasn't report on the popular trend of MRSA in Shanxi Province. In this research, we collected 18 MRSA from the Shanxi Province People's Hospital, and carried a study on their resistance patterns and genotyping. All of 18 MRSA strains were multidrug-resistant bacterium, and the majority of MRSA wereⅢB SCCmec. RAPD analysis of hospital outbreak strains are type A.18 strains of MRSA were all HA-MRSA, while CA-MRSA was not found.