Cheung Terence Kin Man, Chu Yiu Wai, Chu Man Yu, Ma Choi Ha, Yung Raymond Wai Hung, Kam Kai Man
Microbiology Division, Public Health Laboratory Services Branch, Centre for Health Protection, Department of Health, Hong Kong SAR, China.
J Antimicrob Chemother. 2005 Sep;56(3):586-9. doi: 10.1093/jac/dki250. Epub 2005 Jul 20.
To characterize the genetic determinants involved in the reduced susceptibility to ciprofloxacin and cefotaxime in Salmonella enterica serotype Enteritidis clinical isolates obtained from four patients in summer 2003 in Hong Kong.
Three Salmonella Enteritidis isolates from blood culture and one from stool were collected due to their increased resistance to ciprofloxacin and cefotaxime. PFGE analysis was used to investigate their genetic relatedness. Conjugation experiments were employed to show if the genetic determinants involved were plasmid-mediated. MICs of various antimicrobials were determined by VITEK 2 and Etest. Based on the susceptibility and conjugation experiment results, previously described PCR methods were employed to detect sequences homologous to qnr and bla(CTX-M) suspected to be involved in the reduced susceptibility to ciprofloxacin and cefotaxime, respectively.
PFGE analysis showed that the four Salmonella isolates were clonally unrelated. The presence of a qnr-like gene and the CTX-M allele bla(CTX-M-14) on four different transferable plasmids harboured by the four isolates was confirmed.
This is the first report of transferable fluoroquinolone resistance due to a new qnr allele, which appeared to be linked to bla(CTX-M-14), in isolates of Salmonella Enteritidis in Hong Kong.
对2003年夏季从香港4名患者中分离出的肠炎沙门氏菌肠炎血清型临床分离株中对环丙沙星和头孢噻肟敏感性降低所涉及的遗传决定因素进行特征分析。
收集了3株血培养分离的肠炎沙门氏菌和1株粪便分离的肠炎沙门氏菌，因其对环丙沙星和头孢噻肟的耐药性增加。采用脉冲场凝胶电泳（PFGE）分析来研究它们的遗传相关性。进行接合试验以表明所涉及的遗传决定因素是否由质粒介导。通过VITEK 2和Etest测定各种抗菌药物的最低抑菌浓度（MIC）。根据药敏试验和接合试验结果，采用先前描述的聚合酶链反应（PCR）方法检测与qnr和bla(CTX-M)同源的序列，怀疑它们分别与对环丙沙星和头孢噻肟敏感性降低有关。
PFGE分析表明这4株沙门氏菌分离株在克隆上无相关性。证实了这4株分离株携带的4种不同可转移质粒上存在一个qnr样基因和CTX-M等位基因bla(CTX-M-14)。
这是香港肠炎沙门氏菌分离株中因新的qnr等位基因导致可转移氟喹诺酮耐药性的首次报道，该等位基因似乎与bla(CTX-M-14)有关。
