新生儿及产妇感染单核细胞增生李斯特菌分离株的血清型、耐药性及分子特征研究

为探讨广西南宁地区新生儿及产妇感染的单核细胞增生李斯特菌(Listeria monocytogenes, Lm)的血清型、药物敏感性及其分子流行病学特征，本研究回顾性收集2015-2017年广西壮族自治区妇幼保健院新生儿科及产科送检标本中分离的Lm，对其进行体外药物敏感性检测、血清学分型以及多位点序列分型(multilocus sequence typing, MLST)分析菌株间的同源性；同时分析患儿及其母亲的临床特征及危险因素。结果显示，广西南宁地区新生儿感染Lm发病率较低，2015-2017年发病率为0.091‰；所有分离的Lm分属4b(83.3%)和1/2a(16.7%)2个血清型；药物敏感性试验结果显示，Lm对青霉素、氨苄西林、复方新诺明及美罗培南均100%敏感，暂未发现耐药菌株；MLST分型共获得2个序列型(sequence types，ST)，以ST­1型(83.3%)为主。其中分离自同一新生儿患者(Case 2)外周血(Lm2)、耳拭子(Lm3)及其母亲羊水(Lm4)、宫颈分泌物(Lm5)的4株菌具有相同的血清型、药物敏感性表型以及MLST分型。感染Lm的患儿主要表现为发热、肺炎、发绀、败血症及脑膜炎；而产妇感染则具有非特异性的临床特征。结果提示，广西南宁地区存在的Lm菌株为致病性较强的4b、1/2a血清型菌株；Lm可通过母婴垂直传播引起新生儿感染。因此，临床医师应重视孕产妇及新生儿Lm病原学检查、早期诊断和及时合理地使用抗生素预防、治疗，从而减少Lm引起的母婴感染。

Study of serotype distribution,antimicrobial resistance patterns and molecular epidemiology of Listeria monocytogenes isolates from neonatal and maternal in Nanning,Guangxi Province

In order to investigate the genotyping, molecular epidemiological characteristics in neonatal and maternal infection and sources of specimens as well as antimicrobial susceptibility of Listeria monocytogenes(Lm) in neonatal and maternal in Nanning, Guangxi Province. The Listeria monocytogenes isolated from the department of neonatology and obstetrics of Maternal and Child Health Hospital of Guangxi zhuang Autonomous Region from 2015 to 2017 were retrospectively reviewed, in vitro susceptibility testing and serological typing were carried out by a kit, and multilocus sequencing (MLST) for analysis of strains. And the clinical characteristics and risk factors analysis of perinatal listeriosis were analyzed.The results showed that the lower incidence of neonatal Lm infection was 0.091 ‰ between 2015 to 2017 in Nanning of Guangxi. The isolated Lm belonged to two stronger pathogenic strains serotypes [4b (83.3%) and 1/2a (16.7%)]. Drug susceptibility test showed that Listeria monocytogenes were 100% sensitive to penicillin, ampicillin, trimethoprim/sulfamethoxazole and meropenem, and no resistant strains have been found. The genotyping obtains two sequence types (ST) by MLST, mainly ST­1 type (83.3%). Four strains of bacteria were isolated from a newborn patient(Case 2) of peripheral blood(Lm2), ear swab(Lm3) and amniotic fluid(Lm4) and cervical secretion(Lm5) of her mother, which were confirmed to be the same clone by antibiotic sensitivity test, serotype and MLST. The Listeria monocytogenes infections in pregnant women and their newborn infants may be derived from the same clone via vertical transmission.All the neonates in the reported cases had symptoms, including fever, pneumonia, Bluish­colored skin, Sepsis and Meningitis.All the pregnant women in the reported cases had atypical and nonspecific clinical symptoms.Clinical attention should be paid to the pathogen examination of Listeria monocytogenes in maternal and neonatal infections, early diagnosis, prevention and reduction of maternal­infant infection caused by Listeria monocytogenes by timely and reasonable antibiotic treatment.