住院新生儿大肠杆菌分离株脉冲电场凝胶电泳分型

摘要： 目的 通过对新生儿临床分离的大肠杆菌菌株进行分型以示大肠杆菌菌株间的异质性和亲缘性,了解大肠杆菌感染的分子流行病学特征。方法 对2009年9月至2012年5月间北京儿童医院新生儿中心住院的102例患儿的110株大肠杆菌进行脉冲场凝胶电泳分型（PFGE）。结果 110株大肠杆菌临床分离株经PFGE共分65型,相似系数在47.3%～100%,条带在13～22条。优势基因型有13株,相似系数在80.4%～100%。有8对临床分离菌株分别来自于同一患儿,其中7对经PFGE分型方法证实它们属于同一型别（其中1对菌株来自于同一患儿的血液及脑脊液的标本,经PFGE分型证实属于同一基因型,相似系数为93.8%）;另1对显示不是同一型别,亲缘关系较远,故从同源性分析来看不除外不同菌株感染或污染的可能。5株菌株经PFGE证实菌株间亲缘关系较近,其中1株分离株来源的患儿曾与4株分离株来源的患儿同住一病房,考虑为院内获得性感染。结论 PFGE分型方法准确、可靠,可以协助临床明确和区分致病株与非致病株,追踪传染源,对于院内感染的防控起到重要的作用。     

住院新生儿大肠杆菌分离株毒力因子研究

目的 了解住院新生儿大肠埃希菌毒力因子的携带情况。方法 收集2009年9月至2012年5月临床诊断为新生儿肺炎、败血症的连续病例,选择其中抗生素使用之前痰液、血液、脑脊液或脐分泌物培养为大肠埃希菌的病例。根据发病日龄不同,将菌株分为早发型及晚发型。根据标本来源不同,将菌株分为侵袭性感染和非侵袭性感染。选取11种最常见的毒力基因,应用PCR方法对大肠埃希菌菌株进行检测。采用Chromas软件进行读序,测序结果采用Chromas软件直接进行BLAST Search比对。结果 110株大肠埃希菌分离自102例住院新生儿,源于痰液79株（71.8%）,血液18株（16.4%）,脑脊液6株（5.4%）,脐分泌物7株（6.4%）;源于足月儿102株,早产儿8株。早发型27株,晚发型83株;侵袭性感染24株,非侵袭性感染86株。①Einv基因阳性91.8%,CNF1基因阳性21.8%,CNF2基因阳性12.7%,Eagg基因0.9%;共有7种毒力基因携带模式：单纯携带Einv基因66株,单纯携带CNF1基因1株,携带Einv-CNF1基因20株,携带Einv-CNF2基因11株,携带Einv-CNF1-CNF2基因3株,携带Einv-Eagg基因1株。8株（7.3%）11种毒力基因检测均阴性。②携带CNF1或CNF2菌株的37例患儿中22例合并呼吸衰竭,15例需予NCPAP呼吸支持,10例合并多脏器受损,3例肺出血。③8对菌株分别来自同一患儿不同时期或不同部位,其中7对菌株经PFGE分型分别属于同一基因型。3对分别来源于同一患儿不同时期的痰液标本菌株,PFGE分型一致,但毒力基因携带模式不相同。结论 本研究检测到4种大肠埃希菌毒力基因,以Einv基因携带率最高;共发现7种毒力基因携带模式,以单纯携带Einv基因最多见。 CNF1及CNF2基因可能与肺部感染的严重性相关。     

Neonatal escherichia coli infections: concerns regarding resistance to current therapy

Currently recommended antibiotic treatment of suspected neonatal sepsis is ampicillin and an aminoglycoside. Recently, we observed increasing ampicillin and gentamicin resistance in strains of Escherichia coli isolated from neonates at our institution. We therefore reviewed clinical and laboratory records of all neonates with systemic infection, hospitalized from 1994 through 1998, from whom E. coli was isolated from blood and/or cerebrospinal fluid. The influence of perinatal variables (e.g. rupture of foetal membranes > 24h, group B Streptococcus (GBS) colonization, urinary tract infection during pregnancy and the use of antepartum and/or intrapartum antibiotics), and neonatal variables (e.g. gestational age, age at onset of sepsis (early: < or = 72 h, late: >72 h), number of E. coli septic recurrences, and associated underlying medical and/or surgical conditions) on antimicrobial susceptibilities of invasive E. coli isolates was studied. Twenty-three neonates with invasive E. coli infection were identified; most [19 (83%)] presented as late-onset sepsis (LOS). Ampicillin-resistant E. coli were isolated in 75% and 53% of neonates in the early- and late-onset groups, respectively. Gentamicin resistance was found in 50% of early-onset sepsis (EOS) isolates compared with 16% in the late-onset group. Isolates from two neonates with EOS were resistant to both ampicillin and gentamicin. One neonate with EOS and three with LOS had recurrent E. coli sepsis; all isolates were ampicillin-resistant and one was gentamicin-resistant. All these neonates were initially treated with ampicillin and gentamicin. Both groups had associated underlying medical and/or surgical conditions (50% early-onset, 47% late-onset). Maternal GBS colonization occurred in 2 (50%) versus 3 (16%) of EOS and LOS cases, respectively. All GBS colonized women received intrapartum ampicillin prior to delivery. CONCLUSIONS: Ampicillin and gentamicin resistance is emerging in neonatal E. coli isolates from invasive infection. Current- empiric management of neonatal sepsis requires re-evaluation given changing antimicrobial susceptibilities.     

Community-genotype strains of methicillin-resistant Staphylococcus aureus with high-level mupirocin resistance in a neonatal intensive care unit

Aim

The aim of this study was to investigate the genotypes of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MR-MRSA) isolates in our neonatal intensive care unit (NICU) and their potential source.

Study design

One hundred one MRSA isolates obtained from 59 inborn and 42 outborn infants were identified and their antimicrobial susceptibility determined. Using pulse-field gel electrophoresis (PFGE) analysis, MR-MRSA isolates obtained from the neonatal patients in the NICU were compared with those from adult hospitalized in the same hospital and with community-associated MRSA (CA-MRSA) isolates recovered from different hospitals in Korea.

Results

Overall, 47% of CA-MRSA and 79% of healthcare-associated MRSA isolates exhibited high-level mupirocin resistance (HLMR). Forty-five percent of the outborn infants were considered to have CA-MRSA at the time of admission to our NICU. Most HLMR-MRSA isolates from neonates were grouped into a single cluster by PFGE analysis, and which included CA-MRSA isolates with HLMR recovered from outborn infants who were already colonized when they were transferred to our NICU. They belonged to the same PFGE group as the community-genotype strains isolated from different hospitals in Korea. HLMR-MRSA isolates from adults patients were classified as different clones. None of the attending staff in the NICU were nasal carriers.

Conclusion

Community-genotype strains of MRSA with HLMR may be imported to our NICU through obstetrics clinics and contribute to MRSA colonization or infection in facilities with a high rate of admission of outborn infants.     

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??Objective To investigate the antibiotic resistance patterns and epidemiological features of Haemophilus influenzae??HI?? strains??and to provide reference for choosing antibiotics in clinical treatment. Methods A total of 546 strains were identified from 2007 to 2014 in Children’s Hospital??Zhejiang University School of Medicine and 98.7% were isolated from respiratory tract specimens. Three hundred and forty-eight isolates??63.7%?? were from boys and the male-female ratio was 1.76??1. The age of the infected children ranged from 7 days to 13 years. Haemophilus influenza strains were cultured in Haemophilus selective medium. All strains were identified with ?? factor and ?? factor requirement test and the drug-sensitivities tests were performed with disk diffusion method. Cefinase was used to detect β-lactamase. Results Most of the strains??331 isolates??60.6%?? were isolated in spring??while only 23??4.2%?? were isolated in autumn. The β-lactamase positive strains increased annually and the total rate was 26.7%??146???? and 28.0%??153 strains?? were resistant to ampicillin. The multi-resistance strains were 60??11.0%?? and the major multi-resistance type was those resistant to ampicillin??trimethoprim-sulfamethoxazole and clarithromycin at the same time??and the multi-resistance rate in β-lactamase-positive strains were significantly higher than that in β- lactamase- negative strains??χ2??145.1??P??0.005??. Conclusion Most of the Haemophilus influenzae strains are isolated from respiratory samples in children younger than 1 year old in our hospital??and the peak months were February??March??April and May. The resistance rate to ampicillin of HI strains has increased annually??whereas to the second generation of cephalosporin??HI strains are still sensitive and they can be used in clinical treatment as the first choice.     

儿科患者分离鲍曼不动杆菌耐药性及分子流行病学研究

目的分析儿科患者分离出的鲍曼不动杆菌的耐药性及分子流行病学特征。方法以2016年1月至2018年6月内蒙古医科大学附属医院住院患者分离的医院感染鲍曼不动杆菌作为研究对象,采用Vitek-2 Compact全自动微生物鉴定及药敏分析系统进行鉴定及药敏试验,采用脉冲场凝胶电泳(PFGE)方法及多位点序列分型(MLST)进行菌株同源性分析。结果共收集鲍曼不动杆菌临床分离株94株,其中42株来自儿科患者,52株来自成人患者。儿科分离株对亚胺培南、美罗培南和替加环素耐药率分别为7.1%、7.1%和0,成人分离株对这3种抗生素耐药率分别为67.3%、54.8%和5.5%。PFGE分型结果显示,94株菌共分为49个基因型(X1~X49型),52株成人分离株分布于22个基因型,42株儿童分离株分布于33个基因型中。优势基因型为X23型(21株,22.3%),其中成人分离株为18株(85.7%),儿童分离株为3株(14.3%)。X23基因型菌株对碳青霉烯类耐药率为100%,明显高于其他基因型菌株。MLST分型结果显示,X23基因型为ST195,归属于克隆复合体92(CC92)克隆群。结论内蒙古医科大学附属医院鲍曼不动杆菌儿童分离株总体耐药率明显低于成人分离株,基因型多样化特征明显,优势基因型归属CC92克隆群,为我国多地分离优势克隆株。     

新生儿重症监护病房新生儿鼻部金黄色葡萄球菌定植和菌株的分子特征

目的 探讨NICU患儿鼻部金黄色葡萄球菌（简称金葡菌）的定植情况及分离株的基因型和毒力特征。 方法 采集NICU患儿的鼻拭子,分离培养金葡菌,采用头孢西丁纸片法和mecA检测鉴定甲氧西林耐药金葡菌（MRSA）或敏感金葡菌（MSSA）;分析所有菌株MLST和spa分型,并对MRSA菌株进行SCCmec分型,采用PCR方法检测pvl和sasX和21种超抗原毒力基因。 结果 从429例鼻拭子标本分离出79株金葡菌,定植率18.4%,其中MRSA 22株（27.8%）。79株金葡菌共检测出17种MLST型和29种spa型,最常见型分别为ST59（31.6%）和t437（22.8%）。22株MRSA最常见的SCCmec型为Ⅳa（81.8%）。ST59-Ⅳa-t437（63.6%）和ST188-t189（15.8%）分别是MRSA、MSSA最常见的流行克隆。最主要的毒力基因型为seb-sek-seq（10.1%）。MRSA株seb、sek、seq和pvl的携带率明显高于MSSA株,而sei携带率明显低于MSSA株。 结论 NICU患儿鼻部金葡菌定植率较高,ST59-Ⅳa-t437和ST188-t189分别是MRSA、MSSA最常见的流行克隆;分离株毒力基因携带率较高,MRSA与MSSA菌株的毒力基因型存在差异。     

Outbreak of invasive group A streptococcal disease among children attending a day-care center

BACKGROUND: Most cases of invasive group A streptococcal (GAS) disease arise sporadically in the community, but outbreaks of severe invasive GAS infections have been reported in closed environments, such as military populations, family communities and hospitals. An outbreak of invasive GAS disease involving 3 cases of streptococcal toxic shock syndrome (TSS), one with a fatal course, occurred among children attending a day-care center located in Cantabria, Northern Spain. OBJECTIVE: To determine the characteristics of GAS isolates obtained from the outbreak environment. METHODS: GAS isolates obtained from children attending the same day-care facility, staff members, and family contacts were assayed for emm typing, pulse-field gel electrophoresis (PFGE), and toxin-gene content. One isolate obtained from the fatal case was also characterized by multilocus sequence typing. Antimicrobial susceptibility testing was done. Strains from patients unrelated to the outbreak were included for comparison. RESULTS: All GAS isolates from children attending the day-care center, including those from streptococcal TSS cases, shared the same emm type 4, genomic pattern by PFGE (A) and toxin-gene profile. Neither the emm type nor the PFGE pattern or toxin gene profile of the outbreak-associated strains were encountered among GAS isolated from household or staff contacts. CONCLUSIONS: A clone of GAS belonging to emm type 4 and characterized by a specific PFGE pattern and toxin-gene profile was responsible for a community outbreak of streptococcal TSS disease in a child day-care center in Spain. This is the first day-care outbreak reported in our country.     

新生儿社区和院内获得性肺炎的病原学特点及药敏分析

目的探讨新生儿社区获得性肺炎(CAP)和院内获得性肺炎(HAP)的病原分布和药敏情况。方法回顾性分析2010年1月—2014年12月因新生儿肺炎住院且痰培养阳性新生儿的临床资料。结果在3 564例CAP新生儿中共检出病原微生物4 383株,其中细菌3 584株、病毒771、真菌7株及非典型病原体21株。细菌以革兰阴性菌为主,3 045株(85.0%),细菌中排名前三的为肺炎克雷伯菌、大肠埃希菌及金黄色葡萄球菌;病毒以呼吸道合胞病毒为主,693株(89.9%)。在344例HAP新生儿中共检出病原微生物424株,其中细菌402株,真菌17株,呼吸道合胞病毒5株。细菌均为革兰阴性菌,未发现革兰阳性菌,排名前三的为肺炎克雷伯菌、大肠埃希菌及鲍曼不动杆菌。CAP与HAP新生儿中革兰阴性菌产ESBLs菌分别为26.9%、46.8%,差异有统计学意义(P?0.05)。CAP、HAP的肺炎克雷伯菌和大肠埃希菌均对阿米卡星、碳青霉烯类高度敏感。HAP的肺炎克雷伯菌对常用抗菌药物(除阿米卡星、喹诺酮类外)的敏感性普遍低于CAP,差异有统计学意义(P?0.05);HAP的大肠埃希菌对常用抗菌药物(除阿米卡星、喹诺酮类及碳青霉烯类外)的敏感性普遍低于CAP,差异有统计学意义(P?0.05)。此外,还发现耐碳青霉烯类的肠杆菌。结论新生儿肺炎病原菌以革兰阴性菌为主,其中CAP以肺炎克雷伯菌、大肠埃希菌及金黄色葡萄球菌为主,HAP以肺炎克雷伯菌、大肠埃希菌及鲍曼不动杆菌为主。HAP致病菌的产酶率和耐药性均普遍高于CAP,且有多重耐药趋势。     

Gram-negative bacilli associated with catheter-associated and non-catheter-associated bloodstream infections and hand carriage by healthcare workers in neonatal intensive care units.

OBJECTIVE: Bloodstream infections caused by Gram-negative bacilli are a substantial cause of morbidity and mortality in infants in neonatal intensive care units. This study describes the species of Gram-negative bacilli causing bloodstream infections in two neonatal intensive care units, compares characteristics of catheter-related and non-catheter-related bloodstream infections, and compares species and antibiotic resistance patterns of these organisms with those isolated from the hands of nurses working in the same neonatal intensive care units. DESIGN: Interventional study. SETTING: Two high-risk neonatal intensive care units. PATIENTS: Neonates hospitalized for >or =24 hrs. INTERVENTIONS: Prospective surveillance for bloodstream infections was performed in two neonatal intensive care units from March 2001 to January 2003. Hand cultures were obtained quarterly from participating nurses immediately after they performed hand hygiene. MEASUREMENTS AND MAIN RESULTS: There were 298 episodes of bloodstream infections among 2,935 admissions (5.75 episodes per 1,000 patient-days); 77 of 298 (26%) episodes were caused by Gram-negative bacilli. Among these, 47 (61.0%) were catheter-related bloodstream infections (2.61 episodes per 1,000 catheter-days). Eleven and 24 Gram-negative bacilli species were isolated from neonates and nurses, respectively. The most common Gram-negative bacilli causing bloodstream infections were Klebsiella pneumoniae (38.7%), Escherichia coli (21.2%), Enterobacter cloacae (11.2%), and Serratia marcescens (11.2%). In contrast, Acinetobacter lwoffi (18.1%), K. pneumoniae (11.7%), E. cloacae (10.6%), K. oxytoca (10.6%), and Pseudomonas spp. (7.4%) were most commonly isolated from hands of nurses. E. coli, P. aeruginosa, E. cloacae, and E. aerogenes were significantly more likely to cause bloodstream infections than to be isolated from nurses' hands (all p < .001). Although 39% of bloodstream infections were non-catheter-related, there were no significant differences in types of organisms or antimicrobial resistance patterns between catheter-related bloodstream infections and non-catheter-related bloodstream infections (all p > or = .35). Resistance patterns were similar between Gram-negative bacilli isolates from neonates and nurses' hands except for a significantly higher proportion of resistance to cefotaxime and gentamicin among neonatal isolates of K. pneumoniae (p < .05). CONCLUSIONS: Gram-negative bacilli species isolated from neonatal bloodstream infections and nurses' hands varied significantly. Clean hands of providers are an unlikely source of endemic Gram-negative bacilli, suggesting that prevention strategies should focus more on control of endogenous neonatal flora or environmental sources.