The aim of this study was to establish a nationwide antimicrobial resistant surveillance network and obtain information on bacterial resistance in China. A total of 4075 clinical bacterial isolates were collected from 17 hospitals in 15 cities throughout China. Antibacterial minimal inhibitory concentrations (MICs) were determined by the standard agar dilution method recommended by Clinical and Laboratory Standards Institute. The results of the MICs revealed the following bacterial resistance characteristics. Oxacillin resistance was shown by 62.9% of Staphylococcus aureus and 82.89% of Staphylococcus epidermidis strains. Penicillin non-sensitivity was show by 40.7% of the Streptococcus pneumoniae strains, which included 10.5% penicillin-resistant strains and 30.2% penicillin-intermediate strains. Five strains of Enterococci were vancomycin-intermediate, but all Enterococci strains were sensitive to teicoplanin. All Staphylococci were susceptible to glycopeptides. A high resistance to macrolides was a predominant characteristic of the Gram-positive cocci. Enterobacteriaceae strains were clearly resistant to the third generation cephalosporins, with the exception of ceftazidime, and the resistance rates ranged from 20 to 70%. About 65% of the Escherichia coli strains were resistant to fluoroquinolones. Carbapenems remained highly active against all the target bacteria. Latamoxef, piperacillin/tazobactam, cefoperazone/sulbactam and cefepime were all active against Enterobacteriaceae, which showed resistant rates of less than 10%. Imipenem resistance was found in 10.6% of Pseudomonas aeruginosa and 10.4% of Acinetobacter baumannii strains, most of which were multidrug resistant isolates. Combinations of beta-lactam/beta-lactamase inhibitor and fluoroquinolones also had potent antibacterial activity against non-fermenters. Amikacin was active against Enterobacteriaceae and P. aeruginosa. In conclusion, methicillin-resistant Staphylococci, penicillin-insensitive S. pneumoniae, macrolides-resistant Gram-positive cocci, cephalosporin-resistant Enterobacteriaceae, multidrug-resistant nonfermenters and fluoroquinolone-resistant E. coli were revealed to be the most serious problems in terms of bacteria resistance in China. No glycopeptides-resistant Staphylococcus strains were isolated, and the appearance of glycopeptides-resistant Enterococci was seldom.
Little is known about vancomycin-resistant enterococci in China. Thirteen pulsed-field gel electrophoresisconfirmed heterogeneous VanA-type vancomycin-resistant Enterococcus faecium (VRE) isolates were obtained from five Chinese hospitals from 2001 to 2005. The isolates were typed by multilocus sequence typing into nine different sequence types (STs), including five new STs (ST18, ST25, ST78, ST203, ST320, ST321, ST322, ST323, and ST335). Vancomycin resistance in each isolate was encoded on conjugative plasmids; two of the plasmids, pZB18 (67 kbp) and pZB22 (200 kbp), were highly conjugative and were able to transfer at high frequencies of around 10 ؊4 and 10 ؊7 per donor cell in broth mating, respectively. None of the plasmids identified in these isolates carried traA, which is usually conserved in the pMG1-like highly conjugative plasmid for E. faecium, implying that pZB18 and pZB22 were novel types of a highly conjugative plasmid in enterococci. Thirteen Tn1546-like elements encoding VanA-type VRE on the conjugative plasmids were classified into six types (types I to VI), and most of them contained both IS1216V and IS1542 insertions. The isolates carrying the type II element were predominant. The six type elements were different from that of a VanA-type Enterococcus faecalis strain isolated from Chinese chicken meat. The results suggested that the disseminations of VRE in these areas were by Tn1546-like elements being acquired by the conjugative plasmids and transferred among E. faecium strains.
Aims: The characterization of KC122.1, which is a vancomycin‐dependent VRE (Vancomycin‐resistant enterococci) (Enterococcus faecalis) and the first case in Japan of a VRE isolate obtained from chicken meat imported from China. Methods and Results: PCR amplification of vanA, vanS and ddl gene and direct sequencing of the PCR products were performed. KC122.1 was a VanA‐type VRE showing high‐level vancomycin resistance and low‐level teicoplanin resistance, and its vanS gene had three point mutations. The ddl gene of KC122.1 was sequenced and two changes were found at the ninth codon (GCC–GAC) and the stop codon (TAA–CAA). The latter change was also found in the laboratory strain E. faecalis FA2‐2. Conclusions: Three point mutations in vanS resulted in high‐level vancomycin resistance and low‐level teicoplanin resistance. The change at the ninth codon resulted in the inactivation of the ddl gene and vancomycin‐dependent growth. An eight amino acid extension at the C‐terminal did not impair the function of the d‐Ala : d‐Ala ligase. Significance and Impact of the study: This is the first example of the isolation of VRE from chicken meat imported from China and the first vancomycin‐dependent VRE from a nonhuman source.
Aims: The aim of this study was to examine two VanA‐type vancomycin‐resistant Enterococcus faecium (VRE) strains that had been isolated from patients resident in mainland China. This is the first molecular analysis of clinical VRE strains being isolated in mainland China. Methods and Results: Two VanA‐type VRE isolates were isolated from in‐patients at hospitals located in the Chinese cities Beijing and Dalian and were designated C264 and I125. The plasmids pC264V (40 kbp) and pI125V (370 kbp) that were isolated from C264 and I125, respectively, carried a Tn1546‐like element encoding VanA resistance. The vancomycin‐resistant plasmids pC264V and pI125V were transferred by filter mating at frequencies of 10−7 and 10−4 respectively. Sequence analysis of pC264V revealed that two IS1216V sequences and an IS1542 sequence were present within the Tn1546‐like element. pI125V had two IS1216V insertions in the Tn1546‐like element. Conclusions: The two VanA‐type vancomycin‐resistant E. faecium (VRE) strains C264 and I125 were isolated from in‐patients in Chinese hospitals. The vancomycin‐resistant conjugative plasmids pC264V and pI125V plasmids isolated from these strains carried the Tn1546‐like element. The Tn1546‐like element was found to contain the insertion sequences IS1216V and IS1542. Significance and Impact of the Study: This is the first molecular analysis of VanA‐type VRE strains from patients resident in mainland China.
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