Emergence and wide dissemination of CTX-M-type ESBLs, and CMY-2- and DHA-1-type AmpC beta-lactamases in Korean respiratory isolates of Klebsiella pneumoniae

Respiratory isolates of Klebsiella pneumoniae in Korea during 2002-2003 were studied to determine the prevalence and types of extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases (PABLs). ESBL-production was tested by double-disk synergy, and genotypes of beta-lactamases were determined by PCR and sequencing. ESBLs were detected in 28.4% of 373 isolates, and the most prevalent types were SHV-12 (63 isolates) and CTX-M-14 (9 isolates). Forty of 75 ESBL-producers (53.5%) also had PABLs: 21 isolates with CMY-2-like, 17 with DHA-1-like. Pulsed-field gel electrophoresis showed 19 types and 25 of 74 isolates had an identical pattern, indicating nosocomial spread. Dissemination of ESBL- and PABL-producing K. pneumoniae strains in Korea is a particular concern, as it limits the choice of antimicrobial agents for treatment of infections.     

Comparison of in vitro activity of ertapenem with other carbapenems against extended-spectrum beta-lactamase-producing Escherichia coli and Kleibsella species isolated in a tertiary children's hospital

Objective: The purpose of this study was to evaluate the susceptibility of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae clinical isolates to ertapenem in a tertiary pediatric care center in Turkey.

Design/methods: All isolates of ESBL-producing Enterobacteriaceae were collected from clinical specimens from children, and susceptibility tests were done using the Vitek 2 compact system.

Results: Ninety-nine per cent of the ESBL-producing Escherichia coli isolates were found to be susceptible to ertapenem, 99.5% to imipenem and 100% to meropenem. In the Klebsiella species, 91.5% of the isolates were susceptible to ertapenem, 99.3% to imipenem and 100% to meropenem.

Conclusion: The results of our data, including isolates from children, showed that ertapenem had high in vitro activity against the majority of the ESBL-producing E. coli and Klebsiella species, as reported in previously published studies. However, additional clinical studies are required to assess the clinical activity of ertapenem and the clinical importance of the resistant isolates.     

Enterobacteriaceae bacteremia: Risk factors for ESBLPE

Objectives

The increasing prevalence of extended spectrum beta-lactamase producing enterobacteriaceae (ESBLPE) requires defining the use of carbapenems in first intention. We analyzed the associations between enterobacteriaceae bacteremia (EbBact) and ESBLPE carriage during 10 years in a 950-bed teaching hospital.

Methods

We analyzed a 10-year (July 2001 to June 2011) prospective collection of bacteremia cases including 2 databases: (1) EbBact and (2) a computerized database of patients carrying EBLSE. Only one episode of EbBact was analyzed per patient and hospital stay. Factors associated with ESBLPE bacteremia were assessed by univariate and multivariate logistic regression analysis.

Results

Overall, 2355 cases of EbBact were identified, among which 135 (5.7%) were ESBLPE (2001–05: 1.4%, 2006–09: 7.6%, 2010–11: 14.2%). ESBLPE bacteremia was observed in 52 of the 88 (59%) patients carrying ESBLPE and in 83/2267 (3.7%) patients not known to be colonized with ESBLPE. Factors associated with ESBLPE bacteremia in patients not known to be colonized were: female gender (ORa = 0.56, CI95% [0.34–0.91]), hospitalization in the ICU (ORa = 2.51 [1.27–5.05]) or medical/surgical wards (ORa = 1.83 [1.04–3.38]), the period (2006–09, ORa = 4.08 [2.21–8.16]; 2010–11, ORa = 8.17 [4.14–17.06] compared to 2001–05), and history of EbBact (ORa = 2.29 [0.97–4.79]).

Conclusion

In case of EbBact, patients known to be colonized with ESBLPE present with ESBLPE bacteremia in more than half of the cases, requiring carbapenems as empirical antibiotic treatment. The global prevalence of ESBLPE among patients presenting with EbBact not known to be colonized with ESBLPE was 3.7%.     

兰州地区呼吸道感染流感嗜血杆菌分布特点及耐药性分析

目的 分析近几年兰州地区呼吸道流感嗜血杆菌感染的人群和季节性分布特点及菌体耐药性.方法 收集2011-2013年兰州市第一人民医院住院急性呼吸道感染病人呼吸道标本,共检出流感嗜血杆菌312株.用K-B法检测药敏结果,头孢硝噻吩纸片检测β-内酰胺酶.将药敏结果用Whonet软件进行分析,得出各种药物流感嗜血杆菌耐药率.结果 流感嗜血杆菌的感染呈现以下特点：明显的季节性,流感嗜血杆菌感染主要集中在11月和12月,占全年感染数的50％以上,10岁以下儿童感染者98％集中在11月或12月;成年人感染流感嗜血杆菌,感染患者年龄50岁以上者占91.4％;细菌耐药性特点：65.4％的分离株产3-内酰胺酶、氨苄西林、氨苄西林/舒巴坦、头孢呋辛、头孢他啶、复方新罗明、氯霉素耐药率依次为66.3％叼1.0％、9.2％～22.8％、17.3％～20.1％、2.0％～4.4％、31.6％～51.7％、16.3％～18.4％,头孢曲松、头孢噻肟、亚胺培南和美罗培南尚未发现耐药株.结论 流感嗜血杆菌的感染呈明显的季节性分布,感染人群主要为婴幼儿及老年人,耐药率呈逐年上升趋势.     

A profile of the GenePOC Carba C assay for the detection and differentiation of gene sequences associated with carbapenem-non-susceptibility

ABSTRACT

The novel GenePOC/Revogene Carba C assay (GenePOC, Québec, Canada; now Meridian Bioscience, Cincinnati, OH, USA) is a CE-IVD marked, FDA-approved qualitative in vitro diagnostic test for the detection of genes associated with carbapenem-non-susceptibility. Colonies of Enterobacterales can be directly tested without prior DNA isolation. The test consists of a fluorescent-based real-time PCR assay that runs on the centripetal micro?uidic revogene platform, providing results within 70 minutes. The assay was evaluated in two studies comprising a total of 294 molecularly characterized clinical Enterobacterales isolates. The overall sensitivity for the detection of carbapenemase gene sequences with the GenePOC assay was 100% (95% CI, 98.4% to 100). Besides the common KPC, VIM, NDM and OXA-48-like carbapenemase genes, also the very variable IMP variants were all detected. The speci?city of the assay was 100% (95% CI, 98.8% to 100%). In this article the performance of the GenePOC/Revogene Carba C assay is evaluated and other currently available methods for the detection of carbapenemases are reviewed.     

95株致泌尿道感染大肠埃希菌耐药性及耐药基因表型分析

目的了解广东医科大学附属医院泌尿系感染患者大肠埃希菌超广谱β-内酰胺酶型(ESBLs)基因型特征和临床耐药情况。方法收集2015年1~10月该院住院或门诊患者的泌尿系感染患者尿液标本中分离培养获得的大肠埃希菌菌株,双纸片协同试验确定产ESBLs大肠埃希菌,PCR扩增技术进行基因分型。结果 95株大肠埃希菌以CTX-M-14型46例最多;TEM型32例;SHV型30例;CTX-M-1型26例;OXA-1型7例;OXA-2型4例;OXA-10型3例。ESBLs阴性菌株TEM型仅5例阳性,其余基因型别为阴性。ESBLs阳性株对多种抗菌药物的耐药率(碳青霉烯类除外)明显高于ESBLs阴性株,而CTX-M-14、CTX-M-1、TEM、SHV四种基因型别大肠埃希菌对18种抗菌药物的耐药性之间差异无统计学意义(P0.05)。结论广东医科大学附属医院泌尿系感染患者产ESBLs大肠埃希菌以CTXM型为主,对常用抗菌药物耐药率高于ESBLs阴性菌株。不同基因型别产ESBLs大肠埃希菌对抗菌药物耐药率没有明显差异。     

Mechanisms of antimicrobial resistance in Stenotrophomonas maltophilia: a review of current knowledge

ABSTRACT

Introduction: Stenotrophomonas maltophilia is a prototype of bacteria intrinsically resistant to antibiotics. The reduced susceptibility of this microorganism to antimicrobials mainly relies on the presence in its chromosome of genes encoding efflux pumps and antibiotic inactivating enzymes. Consequently, the therapeutic options for treating S. maltophilia infections are limited.

Areas covered: Known mechanisms of intrinsic, acquired and phenotypic resistance to antibiotics of S. maltophilia and the consequences of such resistance for treating S. maltophilia infections are discussed. Acquisition of some genes, mainly those involved in co-trimoxazole resistance, contributes to acquired resistance. Mutation, mainly in the regulators of chromosomally-encoded antibiotic resistance genes, is a major cause for S. maltophilia acquisition of resistance. The expression of some of these genes is triggered by specific signals or stressors, which can lead to transient phenotypic resistance.

Expert opinion: Treatment of S. maltophilia infections is difficult because this organism presents low susceptibility to antibiotics. Besides, it can acquire resistance to antimicrobials currently in use. Particularly problematic is the selection of mutants overexpressing efflux pumps since they present a multidrug resistance phenotype. The use of novel antimicrobials alone or in combination, together with the development of efflux pumps’ inhibitors may help in fighting S. maltophilia infections.     

转座子tnpU基因在多重耐药革兰阴性杆菌中的分布情况

目的研究转座子tnpU基因和β-内酰胺酶在多重耐药革兰阴性杆菌中的分布情况。方法用纸片扩散初筛试验、扩散确证试验进行超广谱β-内酰胺酶（ESBLs）表型检查,头孢西丁三维试验进行AmpC β-内酰胺酶的表型检查,纸片协同试验筛选产金属β-内酰胺酶（MBL）菌株;用多重聚合酶链反应（PCR）技术扩增转座子tnpU基因,并进行DNA测序;用MIC药敏法分析多重耐药革兰阴性杆菌的药物敏感性。结果转座子tnpU的总检出率为25．5％。在各菌种的检出率分别为大肠埃希菌占6.3％（3株）、肺炎克雷伯菌占8．3％（1株）、鲍曼不动杆菌占33-3％（20株）、铜绿假单胞菌占43．2％（16株）;β-内酰胺酶表型检测中,ESBLs的检出率最高,转座子tnpU基因阳性的菌株大多数B．内酰胺酶表型为阳性;转座子tnpU基因阳性菌株对抗生素的耐药率显著高于转座子阴性菌株（P〈0．05）。结论转座子tnpU基因在非发酵菌中的分布较广泛,可能在多重耐药机制中起重要作用。     

产超广谱β-内酰胺酶细菌的临床分布及耐药特征

目的 了解本地区产超广谱β-内酰胺酶(ESBLs)细菌的临床分布及耐药特性。方法 采用双纸片扩散法对临床分离的革兰阴性杆菌(G^-B)进行ESBLs确证试验，并将ESBLs产生株的临床分布及其对常用抗菌药物的耐药性进行分析。结果 在613株G^-B中，共检出产ESBLs上细菌108株，检出率为17．6％。ESBLs产生株主要见于大肠埃希菌(45／155，29．0％)和肺炎克雷伯菌(39／133，29．3％)；标本来源主要为痰液标本，其次为尿液标本和创面分泌物；科室分布以重症监护病房(ICU)和呼吸科最多，其次为肾内科和神经内科：ESBLs产生株对大多数常用抗菌药物呈现高度耐药，敏感性较高的只有亚胺培南、哌拉西林／三唑巴坦等抗菌药物。结论 产ESBLs细菌临床分布广泛，对大多数抗菌药物呈现多重耐药，需引起临床的高度重视。     

临床常见产AmpC β-内酰胺酶菌株中染色质ampC共同序列的研究

目的分析临床常见AmpC β-内酰胺酶（简称AmpC酶）产酶菌株中染色质ampC的基因序列,从而为AmpC酶的分子生物学检测以及其调控机制研究提供理论依据。方法 57株临床常见AmpC酶产酶菌株分离自医院感染患者样本,抽提细菌染色质DNA,聚合酶链反应（PCR）扩增ampC基因并连接入pMD19-T载体,双链测序后比对同种细菌之间和不同种细菌之间染色质ampC基因的同源性和共同序列。根据共同序列设计引物,进一步利用该引物检测染色质ampC。结果 57株细菌的基因组中,使用PCR扩增出染色质ampC基因41株,并成功测定了其ampC基因的序列。比对后发现大肠埃希菌、阴沟肠杆菌、鲍曼不动杆菌和产气肠杆菌的染色质ampC菌种内有很高的同源性,但细菌之间的同源性较低。根据共同序列设计出菌种特异性PCR引物,能够有效的鉴定出染色质ampC基因。结论大肠埃希菌、阴沟肠杆菌、鲍曼不动杆菌和产气肠杆菌各自染色质ampC具有高度同源性,其菌种特异性的ampC引物可用来检测其染色质ampC的存在。