Antimicrobial resistance, genotypic characterization and pulsed-field gel electrophoresis typing of extended spectrum β-lactamases-producing clinical Escherichia coli strains in Macao, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The rise of the production of CTX-M class extended spectrum β-lactamases (ESBLs) has been well documented in traveling countries but no data are found for Macao, an international travel city. The objectives of this study were to identify the antimicrobial resistance pattern, and determine the prevalence, genotype and clonal relationship of ESBLs in 209 clinical Escherichia coli strains from Macao, China.</p><p><b>METHODS</b>Antimicrobial susceptibility test was performed to determine the resistance patterns of the isolates using the disk diffusion method with 17 antimicrobial agents. Phenotypic detection was screened and confirmed according to the Clinical and Laboratory Standards Institute. Genotypic characterization was detected by isoelectric focusing analysis, polymerase chain reaction and sequencing. The clonal relationship between the different ESBL isolates was studied by pulsed-field gel electrophoresis (PFGE).</p><p><b>RESULTS</b>Imipenem and meropenem exhibited 100% susceptible among 209 strains. Overall, 82.3%, 67.3%, 52.9%, 51.2% and 51.0% of the isolates displayed resistance to ampicillin, tetracycline, ciprofloxacin, sulfamethoxazole trimethoprim and gentamycin. The prevalence rate of ESBLs was 30.1%. Antibiotic resistances were found to be significantly higher among the ESBL producing group compared to non-ESBL producing group. We detected CTX-M-14 to be the major genotypic characterization of ESBLs (76.2%). Two strains showed indistinguishable patterns by PFGE.</p><p><b>CONCLUSIONS</b>The prevalence of antimicrobial resistance is alarming high in Macao. Antimicrobial resistance is significantly higher among the ESBL producing group. This study documented CTX-M-14 as the predominant ESBL type. Although indistinguishable pattern was found between two strains, it was too small to decide whether any of the investigated strains was epidemic. Our findings may be also pertinent for other geographic areas undergoing similar travel characteristics to understand the corresponding effects on bacterial populations.</p>

In vitro study on bacterial growth enhancement in the presence of TNF-?,IL-1? and IL-6 / 中国感染与化疗杂志

Objective To conduct an in vitro study of the growth of Pseudomonas aeruginosa,Staphylococcus aureus and Acin- etobacter spp.,and evaluate their response to various concentrations of tumor necrosis factor(TNF)-?,interleukin (IL)-1?, and IL-6.Methods To monitor the growth of bacteria incubated with the cytokines TNF?,IL-1?and IL-6 that were added to RPMI 1640 medium in various concentrations (10,50.100,500 pg,1 and 10 ng) at 2,4 to 6,8 and 16-18 h.The bacterial concentration was estimated when the mixtures of cytokines and specific neutralizing monoclonal antibodies (MoAbs) were in- cubated.Results We found that all three bacterial species showed concentration-dependent growth enhancement when incubated with one or more tested cytokines.Blockade by specific neutralizing cytokine significantly inhibited cytokine-induced growth. When compared with control,the 6 h growth response was maximal with IL-1?for Staphylococcus aureus and Acinetobacter spp.,and with IL-6 for Pseudomonas aeruginosa.Conclusions In this study we provide additional evidence for a newly de- scribed mechanism for bacterial proliferation in the presence of exaggerated and protracted inflammation.The effect that cyto kine-induced growth enhancement inhibited by specific neutralizing cytokine MoAbs may be useful for antimicrobial therapy.