广东省福氏志贺菌F4c的病原学特征分析

目的了解广东省新型福氏志贺菌F4c菌株的流行与病原学特征。方法对2000—2004年广东省痢疾监测收集的227株志贺菌进行血清学分型,并对其中46株福氏志贺菌F4c菌株以及2004、2007年2起痢疾暴发监测收集的5株和2005年散发病例收集的2株F4c菌株（共53株）进行生化、血清学试验、药敏试验和PFGE分型;并用气相色谱仪测定其中6株的脂肪酸成分。结果 2000—2004年广东省痢疾监测发现：227株志贺菌除20株为宋内氏志贺菌外,其余均为福氏志贺菌,其中F2a的菌株数最多,有55株（占菌株总数的24.2%）,其比例从2000年的44.0%下降至2004年8.6%,F4c有46株,占20.3%,从2000年未检出F4c菌株,至2003年F4c占菌株总数的比例上升至71.7%（38/53）。53株F4c的生化结果符合志贺菌特征,血清学均为福氏多价＋,IV型因子＋,7,8群血清＋;53株F4c菌株对头孢曲松、诺氟沙星、头孢噻肟和环丙沙星4种药物敏感,敏感率分别为100.0%、92.9%、92.9%、71.4%,对四环素、复方新诺明、萘啶酸、氯霉素和氨苄西林均产生耐药,除氨苄西林的耐药率为91.7%外,其余均达到100.0%。PFGE对43株F4c进行分子分型,共分为21个不同的型别;6株志贺菌F4c的主要脂肪酸成分为12∶0酸、14∶0酸、Sum In Feature2、Sum In Feature 3、16∶0酸、17∶0 cyclo、Sum In Feature 8和19∶0 cyclo w8c等8种脂肪酸。结论福氏志贺菌4c菌株用PFGE进行分子分型在整体上表现出较大的遗传多样性;福氏志贺菌4c在广东省的流行出现上升趋势,并在部分地区暴发疫情,提示F4c菌型可能逐步演变成为一类稳定的福氏志贺菌菌株。

Pathogenic characterization of shigella flexneri 4c isolated from Guangdong Province

Objective To understand the prevalence and pathogenic characterization of serologically atypical strains of shigella flexneri 4c isolated from Guangdong Province.Methods 227 shigella strains collected from dysentery surveillance in Guangdong Province from 2000 to 2004 were tested by serum agglutination;46 shigella flexneri 4c strains of these 227 shigella strains and 5 F4c strains from dysentery outbreak in 2004 and 2007 as well as two F4c strains collected from sporadic cases in 2005 were tested by biochemistry,serum agglutination,antibiotic susceptibility and PFGE;and the fatty acid constitutes of 6 shigella flexneri strains were determined using gas chromatograph technique.Results Etiologic analysis of dysentery surveillance in Guangdong Province from 2000 to 2004 showed that among the 227 shigella strains,20 strains were shigella sonnei,the rest were shigella flexneri.55 strains were F2a,accounting for 24.2%;and its proportion was from 44.0% in 2000 down to 8.6% in 2004.46 strains were F4c,accounting for 20.3%.F4c strain was not detected in 2000,while the proportion of F4c was increased to 71.7%（38/53） of the total strains in 2003.The biochemistry characteristics of these 53 F4c strains were consistent with shigella.F4c strains agglutinated with the serum of poly B,IV factor and Groups 7 and 8.The results of 9 antibiotic susceptibility tests of 53 F4c strains demonstrated that they were sensitive to norfloxacin,cefotaxime,ciprofloxacin and ceftriaxone.The drug resistance to tetracycline,trimesulf,nalidixan,and chloromycetin reached 100%,and ampicillin also reached 91.7%.43 F4c strains can be divided into 21 types by PFGE,eight kinds of fatty acids were found;they were 12∶0 acid,14∶0 acid,Sum In Feature 2,Sum In Feature 3,16∶0 acid,17∶0 cyclo,Sum In Feature 8 and 19∶0 cyclo w8c,respectively.Conclusion The PFGE analysis demonstrated that most of the F4c strains displayed a large genetic diversity.The prevalence of F4c in Guangdong Province and the outbreaks caused by F4c indicate that F4c may gradually evolve into a class of stable strains of shigella flexneri.