[Antimicrobial resistance and molecular epidemiology of coagulase-negative Staphylococci in Chengdu]

To investigate the antimicrobial resistance and molecular prevalence of coagulase-negative Staphylococcus (CONS) in Chengdu.

Disk diffusion method was used to test antimicrobial resistance of 2038 CoNS isolated from 15 hospitals and 6 CDCs (center for disease control and prevention) in Chengdu, the results were interpreted according to the guideline of National Committee for Clinical Laboratory Standards. CoNS were typed with plasmid and PFGE (pulsed field gel electrophoresis) profiles.

(1) S. epidermidis, S. haemolyticus, and S. saprophyticus accounted for 82.2% of the CoNS isolated from Chengdu, with different constituent ratio of CoNS among patients, medical staff, sick children and normal people. (2) CoNS resisted to one or more antimicrobial agents with resistance rate of 80.4% . CoNS resisted highly to SMZ, penicillin-G, ampicillin, erythromycin, TMP-SMZ and tetracycline, but were susceptible to vancomycin, norfloxacin and amikacin. 25 antimicrobial resistance profiles were acquired, and Amp + Ery + P-G + SMZ, Amp + Gen + Str + Tet, Amp + P-G + Tet, Chl + Ery + P-G + SMZ + TS, Ern + Nov + P-G + SMZ + TS, as well as P-G + SMZ + TS were main profiles. The main antimicrobial resistance profiles of CoNS isolated from patients, medical staff, sick children and normal people had some differences, but the antimicrobial resistance of main biochemical subtypes was similar a lot. (3) Plasmid prevalence of CoNS was 72.9%, with 12 plasmid profiles ( I -H ) of all CoNS. The main profiles were I , U , and MI type, which accounted for 80.1% of 1485 CoNS with plasmid. (4) 29 PFGE genotypes and 112 subtypes were found in 2038 strains. Genotypes A, B, C, D and E were the predominant types in CoNS from patients, medical staff, sick children and normal people and contributed 89.1% to 2038 CONS. Genotypes A was the major type and had similar constituent ratio in CoNS from 4 sources, and no enough similarity of constituent ratio in other dominant genotypes.

Antimicrobial resistance rate of CoNS was very high in Chengdu and multi-resistance existed in various populations generally. High homology was found in CoNS from different sources, especially from medical staff as well as sick children and infant, and a latent inter-transmission may occur in these populations. So it was no time to delay the monitoring and investigation of antimicrobial resistance and molecular epidemiology for CoNS in Chengdu.