High prevalence of blaCTX-M extended-spectrum β-lactamase genes in Escherichia coli isolates from pets and emergence of CTX-M-64 in China

As a cause of community-acquired infections, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli constitute an emerging public-health concern. Few data on the molecular epidemiology of ESBL-producing E. coli isolates from pets are available in China. Detection and characterization of ESBL genes (bla_CTX-M, bla_SHV and bla_TEM) was conducted among 240 E. coli isolates recovered from healthy and sick pets in South China from 2007 to 2008. The clonal relatedness of ESBL-producing E. coli isolates was assessed by pulsed field gel electrophoresis. ESBL-encoding genes were identified in 97 (40.4%) of the 240 isolates and 96 (40.0%) of them harbored CTX-M. The most common CTX-M types were CTX-M-14 (n = 45) and CTX-M-55 (n = 24). The recently reported CTX-M-64 was identified in three isolates. Isolates producing CTX-M-27, -15, -65, -24, -3 and -9 were also identified. Ten isolates carried two or three CTX-M types, with the combination of CTX-M-14 and CTX-M-55 being the most frequent (n = 6). ISEcp1 was identified in the upstream region of 93 out of the 107 bla_CTX-M genes (86.9%). The sequence of the spacer region (45 bp) between ISEcp1 and the start codon of all bla_CTX-M-55 genes (except four) was identical to that of bla_CTX-M-64. No major clonal relatedness was observed among these CTX-M producers. It is suggested that the horizontal transfer of bla_CTX-M genes, mediated by mobile elements, contributes to their dissemination among E. coli isolates from pets. Our finding of high prevalence of ESBL in E. coli of companion animal origin illustrates the importance of molecular surveillance in tracking CTX-M-producing E. coli strains in pets.     

Extended-Spectrum ��-Lactamase�CProducing Enterobacteriaceae in a Malian Orphanage

We show high rates of extended-spectrum β-lactamase–producing Enterobacteriaceae carriage among the staff and children at an orphanage in Bamako, Mali. Enterobacteriaceae colonized in 100% and 63%, respectively, of the 38 children and 30 adults studied. Use of antimicrobial drugs appeared excessive and inappropriate; decontamination and hygiene protocols were also questioned.     

2009年至2010年23种抗菌药物对大肠埃希菌敏感趋势分析

目的 通过对医院分离的大肠埃希菌药物敏感性报告分析,为临床提供合理选择抗菌药物的依据,避免盲目使用或滥用抗菌药物,延缓或减少耐药菌株的产生,提高感染治愈率.方法 采用2009年至2010年医院检验科提供的感染患者送检标本经分离、菌种鉴定和药物敏感性分析后的实验数据报告,对其报告进行统计分析.结果 2009年至2010年,医院分离出大肠埃希菌559株,居所有分离菌株数量之首;除了碳青霉烯类、头孢菌素类、阿米卡星和部分β-内酰胺酶抑制剂组成的复方制剂以外,其他抗菌药物对大肠埃希菌的敏感率很低甚至完全耐药,并且高于2006 - 2007年度卫生部全国细菌耐药监测网(Mohnarin)革兰阴性杆菌耐药情况报告发布的数据.结论 随着抗生素大量及长时间的使用,尤其是第3代、第4代头孢菌素的广泛应用或侵袭性操作等因素,导致大肠埃希菌产超广谱β-内酰胺酶(ESBLs)甚至产金属β-内酰胺酶(NDM -1)增加,耐药现象严重,给临床治疗带来困难.     

Correlation of TEM, SHV and CTX-M extended-spectrum beta lactamases among Enterobacteriaceae with their in vitro antimicrobial susceptibility

Purpose: The present study was carried out to characterize the ESBL types and evaluated their in vitro activity against a collection of Gram negative bacteria (GNB) from a multicentric Indian surveillance study. Material and Methods: During January 2005 to June 2006, six tertiary care centres in India forwarded 778 non-duplicate GNB to our reference laboratory. Three hundred GNB from this collection were selected based on clinical significance and were used in the present study. Tested isolates included Escherichia coli (167), Klebsiella spp. (122) and Enterobacter spp. (11). ESBL screening and confirmation was performed for all the isolates. Minimum inhibitory concentration of imipenem, meropenem, ertapenem, levofloxacin, amikacin, piperacillin/tazobactam and ceftriaxone was determined by the E-test method. Molecular typing of the ESBLs was performed by polymerase chain reaction among the 121 selected isolates. Results: The study showed excellent susceptibility among the strains to imipenem (100%), meropenem (100%) and ertapenem (98.7%); good susceptibility to amikacin (89.7%) and piperacillin/tazobactam (85.3%) was observed. TEM and CTX-M were predominantly found in E. coli (39.2%) while, among the Klebsiella spp., TEM, SHV and CTX-M occurred together in 42.6% of the isolates. Conclusion: More than one ESBL was produced by many strains, and this was correlated with increased resistance levels. Carbapenems continue to show good in vitro activity and ertapenem is a potential alternative to imipenem and meropenem. Continued antimicrobial resistance surveillance is warranted in light of these findings.     

儿童肺炎克雷伯菌超广谱β-内酰胺酶的检测及药物敏感分析

目的了解儿童肺炎克雷伯菌感染状况、特点及细菌耐药性分析,以期指导临床合理用药。方法采用VITEK全自动微生物分析鉴定系统对临床分离的肺炎克雷伯菌菌株进行细菌鉴定和药物敏感试验。结果共分离出肺炎克雷伯菌122株,其中产超广谱β-内酰胺酶(ESBLs)肺炎克雷伯菌62株(50.82%),不产ESBLs肺炎克雷伯菌60株(49.18%);产ESBLs肺炎克雷伯菌62株中有45株(72.58%)从痰液分离中得到。分离出来的产ESBLs肺炎克雷伯菌菌株对青霉素类抗生素如氨苄西林、替卡西林及头孢噻吩完全耐药,对头孢西丁和亚胺培南完全敏感;分离出来的不产ESBLs肺炎克雷伯菌菌株对青霉素类抗生素氨苄西林完全耐药,对头孢西丁和亚胺培南完全敏感。结论肺炎克雷伯菌产ESBLs率较高;临床治疗前应尽可能进行肺炎克雷伯菌培养及药敏试验,以合理和规范用药。     

产ESBLs、AmpC、KPC酶的葡萄糖不发酵细菌的耐药性分析及临床分布

目的了解本地区葡萄糖不发酵细菌中泛耐药菌（代表株铜绿假单胞菌、鲍曼不动杆菌、嗜麦芽窄食单胞菌）在临床标本中的分离与耐药情况,为临床合理使用抗生素提供指导。方法对临床分离的180株葡萄糖不发酵细菌进行分类鉴定和药敏试验,并用纸片扩散法筛选出产超广谱β-内酰胺酶（ESBLs）、头孢菌素酶（AmpC酶）及碳青霉烯类水解酶（KPC酶）的耐药菌株。结果在葡萄糖不发酵细菌的构成比中,其中产超广谱β-内酰胺酶（ESBLs）56株（31.1%）,产AmpC酶22株（12.2%）,KPC酶2株（1.1%）;同时产ESBLs和AmpC酶16株（8.9%）,同时产ESBLs、AmpC、KPC酶1株（0.6%）。3种主要葡萄糖不发酵细菌对头孢他啶、头孢三嗪、头孢噻肟、哌拉西林的耐药率最高,其中铜绿假单胞菌对阿米卡星、左氧氟沙星、环丙沙星耐药率较低,鲍曼不动杆菌对亚胺培南、左氧氟沙星耐药率较低,嗜麦芽窄食单胞菌对复方新诺明、环丙沙星耐药率较低。结论葡萄糖不发酵细菌中泛耐药菌特别是铜绿假单胞菌、鲍曼不动杆菌、嗜麦芽窄食单胞菌均有较高的多重耐药性,临床上应重视葡萄糖不发酵细菌引起的感染,根据药敏试验结果合理使用抗生素。     

Prevalence of multiresistant Gram-negative organisms in a surgical hospital in Ho Chi Minh City, Vietnam

OBJECTIVE: To determine resistance patterns of multiresistant Gram-negative organisms at a surgical hospital in Ho Chi Minh City, Vietnam, in order to guide appropriate antibiotic prescribing and improve infection control procedures. METHOD: All samples sent in for microbiological analysis over a 3-month period were included. A resource neutral double disc-diffusion test was introduced to detect the presence of extended-spectrum beta-lactamase (ESBL) production. RESULTS: We obtained 350 bacterial isolates from clinical specimens; 87.4% were Gram-negative bacteria (GNB). Of these, 88.9% were Enterobacteriaceae, of which 14.7% produced ESBL. Fifteen (37.5%) of these were isolated within 48 h of admission. Resistance to gentamicin and ciprofloxacin occurred in 70.0% and 72.5% of those organisms that produced ESBL and in 39.5% and 38.7% of those that did not. Resistance to third-generation cephalosporins was common: 36.7% of all GNB were resistant to ceftriaxone, 34.0% to cefotaxime, 19.6% to ceftazidime and 36.7% to cefoperazone. CONCLUSION: Multiresistant Gram-negative organisms are common and pose a challenge to antibiotic therapy. Successful implementation of a simple test to detect ESBL production allowed reporting of these organisms, appropriate antibiotic prescribing and infection control interventions. Development of antibiotic-prescribing guidelines must take into account these resistance patterns.     

Spread of novel expanded-spectrum β-lactamases in Enterobacteriaceae in a university hospital in the Paris area, France

In 2002, 28 non-duplicate enterobacterial isolates producing extended-spectrum beta-lactamases (ESBLs) were collected from infected patients at the Bicêtre Hospital in Paris, France. Escherichia coli was the predominant ESBL-positive enterobacterial species, comprising ten (36%) of the isolates. CTX-M enzymes (CTX-M-3, CTX-M-10, CTX-M-14 and CTX-M-15) were produced by 11 (39%) of the isolates (six E. coli, two Enterobacter cloacae, one Enterobacter aerogenes, one Proteus mirabilis and one Citrobacter freundii). Other ESBLs, such as VEB-1 and PER-1, were also detected, but less frequently.     

临床分离菌超广谱β-内酰胺酶的检测及耐药性分析

目的了解本地区产ESBLs菌的比例及耐药特征,为临床医师治疗选药时提供参考。方法按NCCLS推荐的ESBLs确证试验对大肠埃希菌和肺炎克雷伯菌进行ESBLs检测并用ATBExpression细菌鉴定及药敏智能系统进行耐药性的测定。结果在179株大肠埃希菌、90株肺炎克雷伯菌中ESBLs的检出率为31%、27%;产ESBLs菌对青霉素类、头孢菌素类抗生素表现为很高的耐药性,对氨基糖苷类、喹诺酮类和磺胺类药物交叉耐药,但对含酶抑制剂的复合制剂和碳青霉烯类药物敏感。结论治疗ESBLs菌引起的感染应以含酶抑制剂的复合制剂和碳青霉烯类为首选。