Antimicrobial susceptibility of gram-positive organisms: results from China Antimicrobial Resistance Surveillance Trial Program, 2013-2014

Objective\r\nTo investigate the gram-positive coccus resistance in nationwide\u0027s tietiary hospitals and understand the trend of antimicrobial resistance.\r\n\r\n\r\nMethods\r\nAll the clinical isolates were collected from 19 tertiary hospitals in 19 cities nationwide over the period from July 2013 to June 2014 according to same protocol. About 140 strains were collected from one hospital. The minimal inhibitory concentrations (MICs) were tested using agar/broth dilution method recommended by Clinical and Laboratory Standards Institute (CLSI) in central laboratory (Institute of Clinical Pharmacoloty, Peking University First Hospital). The susceptibilities of isolates to antimicrobial agents were determined by using CLSI or European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2015 guideline, and software SPSS 17.0 was used to caculated MIC50, MIC90, MICrange, susceptible and resistant rates.\r\n\r\n\r\nResults\r\nA total of 2 382 pathogenic islates were studied. Based on the MIC results, the prevalence rate of methicillin resistant Stapylococcus aureus (MRSA) and methicillin resistant Stapylococcus epidermidis (MRSE) reached 43.9% (330/751) and 86.6% (129/149), respectively.S. aureus were 100% (751/751) susceptibility to linezolid, teicoplanin and datomycin, but resistances for the three drugs were observed among coagulase negative Staphylococci (CoNS). One vancomycin intermediate S. aureus was detected for the first time. Antibiotic resistance rate of Enterococcus faecalis to ampicillin was 5.8% (18/311), while Enterococcus faecium reached up to 90.1% (309/343). Fourteen Enterococcus spp. were resistant to glycopeptides, so vancomycin resistant Enterococcus (VRE) was 2.1% (14/654). Nonsusceptibility rate of linezolid was 2.6% (17/654), showing slight increase than last time. The prevalence of penicillin nonsusceptible Streptococcus pneumoniae (PNSSP) was 17.9% (61/340) based on non-meningitis and parenteral administration criterion; while for cases of oral penicillin, the rate was 72.1% (245/340). There were no significant differences of resistance rates among various groups of strains, such as collected from ICU or non-ICU, different age groups or specimens (t≤1.487, P≥0.145). MRSA in children (≤14 years) was 49.4% (76/154), showed increasing trend when compared with data from 2009-2010 (18.0%, 25/139).\r\n\r\n\r\nConclusions\r\nCompared with past surveillance result, MRSA and VRE detection ratio were steady. Glycopeptides and new antimicrobial agents exhibited good acivity against gram-positive cocci. Slightly growth of linezolid non-susceptible Enterococcus and quinolone resistance Streptococcus agalactiae should be payed more attention. Bacterial resistance in children is a problem in China.(Chin J Lab Med, 2016, 39: 120-129)\r\n\r\n\r\nKey words: \r\nDrug Monitoring; Drug Resistance, Bacterial; Gram-Positive Bacteria; Microbial Sensitivity Tests