婴幼儿眼部感染肺炎链球菌的血清型及多位点序列分型分析

Serotype and multilocus s sequence typing analysis of Streptococcus pneumoniae in infants and young children with eye infections

目的研究婴幼儿眼部感染肺炎链球菌（SP）的血清型及多位点序列（MLST）分型,为临床治疗提供依据。方法采集2014年1月-2015年6月眼部感染患儿在入院当日的结膜囊分泌物,进行病原菌培养和鉴定,分离出SP 42株,分析42株SP对于抗菌药物的药敏试验结果,大环内酯型药物的耐药基因与SP血清型的检测情况,并选取其中20株SP进行MLST分型。结果 42株SP对头孢噻肟及万古霉素均敏感,敏感率达到100.0%,对妥布霉素和夫西地酸以及青霉素的敏感率均〉90%;在耐药性方面,SP对头孢噻肟和左氧氟沙星,以及万古霉素的耐药率均为0,对克林霉素及红霉素的耐药率较高,均〉80%;42株SP共检出37株呈阳性的ermB基因,占88.10%,且均对红霉素存在高度耐药;另有3株呈阳性的mefE基因,占7.14%,并与ermB基因同时呈阳性,和耐药表型基本一致,本组一共检出12类血清型,其中19型最多,共12株,占28.57%,较其他各种类型的检出率显著高,差异有统计学意义（χ^2=3.756,P=0.001）,选取20株SP共检出17类序列型,其中3株是ST320型,2株是ST505型,其余序列性均为散在性分布,无优势序列型,根据MLST网站检索的等位基因谱及序列型结果,20株SP菌株间的关系呈树状图分布,可表现为多克隆群体性结构。结论引发婴幼儿眼部感染的SP在血清型及MLST分型较为分散,表现为多克隆群体性结构,且对眼科常用药物存在较高耐药性,临床可考虑选择妥布霉素和夫西地酸用于预防控制SP感染。

OBJECTIVE To investigate serotypes and multilocus sequence typing（MLST）of Streptococcus pneumoniae（SP）in infants and young children with eye infections,so as to provide evidence for clinical treatment.METHODS Infants and young children with eye infections were chosen from Jan.2014 to Jun.2015,their secretion of conjunctival sac were collected in the hospital on the day of admission,and then cultured and identified.Totally 42 strains of SP were detected.The results of drug sensitivity test of 42 strains of SP,and the detection of drug resistance genes and SP serotypes were analyzed,and 20 strains of SP were selected for MLST.RESULTS The 42 strains of SP were sensitive to cefotaxime and vancomycin,and the sensitive rates reached 100%,and the sensitive rates to tobramycin,fusidic acid,and penicillin were above 90%.In terms of drug resistance,the resistant rates of SP to cefotaxime,levofloxacin and vancomycin were 0%,to clindamycin and erythromycin were above80%.ErmBgene was detected in 37 strains of SP,accounting for 88.10%,which were highly resistant to erythromycin.Another 3strains of positive mefEgene were detected,accounted for 7.14%,and were co-positive with ermBgene,and the drug resistance phenotypes were the same.In this group,there were 12 kinds of serum types,among which type 19 was the most,with 12 strains,accounted for 28.57%,and the detection rate was significantly higher than other types,（χ^2=3.756,P=0.001）.There were 17 types of sequence types in selected 20 strains,including 3strains of ST320,2strains of ST505,and other strains with scattered types in the distribution with no dominant sequence.According to the MLST site,the relationship between the 20 strains of SP was the distribution of the tree,which could be expressed as a multi clonal population structure.CONCLUSION The SP caused infant eye infections has scattered serotype and MLST,with a polyclonal population structure,and has high drug resistance to drugs commonly used in ophthalmology,so tobramycin and fusidic acid were considered for prevention and control of SP infection.