Is it time to reconsider initial antibiotic treatment strategies for severe urinary tract infections in Europe?

Until recently, most reported cases of bacteraemia caused by multidrug-resistant strains of Enterobacteriacae producing an extended-spectrum beta-lactamase (ESBL) in Europe have been nosocomial in origin. However, increasing numbers of reports of community-acquired bacteraemia and urinary tract infection caused by ESBL-producing microorganisms suggest that the geographical origin of patients should be taken into account as a risk-factor for possible ESBL production. Early identification of patients at high-risk of infection with ESBL-producing microorganisms, based on their geographical origin and travel history, should help to optimise initial antibiotic treatment strategies for severe urinary tract infections in Europe.     

Comparison of screening methods for TEM- and SHV-derived extended-spectrum β-lactamase detection

Objective   To compare common extended-spectrum β -lactamase (ESBL) screening methods and β -lactams for their ability to detect TEM- and SHV-related ESBL enzymes.
Methods   This study compared disk diffusion testing by NCCLS methodology, the Jarlier double disk test, a disk-on-disk test, a modified three-dimensional test and the E test method for their sensitivity and specificity in detecting TEM- and SHV-related ESBL producers. Three negative and 22 positive controls were studied. These were two Klebsiella pneumoniae and 23 Escherichia coli transconjugants. Seventeen β -lactam antibiotics were tested: cefamandole, cefotetan, cefoxitin, cefuroxime, cefixime, cefoperazone, cefotaxime, cefpodoxime, cefsulodin, ceftazidime, ceftibuten, ceftizoxime, ceftriaxone, moxalactam, cefepime, cefpirome and aztreonam.
Results   NCCLS disk diffusion was 14% sensitive with ceftriaxone, 36% with cefotaxime, 64% with aztreonam, 68% with cefpodoxime, and 73% with ceftazidime. Cefoperazone, cefamandole, cefpodoxime and cefpirome showed 91% sensitivity using the Jarlier test. Using the disk-on-disk test, cefsulodin showed 95% sensitivity, and cefoperazone, cefepime and cefamandole showed 91% sensitivity. With the modified three-dimensional test, cefoperazone, cefpodoxime and cefpirome showed 91% sensitivity.
Conclusions   For practical reasons, we would recommend use of either the Jarlier test or the commercial cephalosporin disks containing clavulanic acid to screen for ESBL producers. Cefoperazone, cefamandole, cefpodoxime and cefpirome showed good sensitivity across the methods tested.     

Clinical epidemiology of ciprofloxacin-resistant Proteus mirabilis isolated from urine samples of hospitalised patients

This study investigated the clinical characteristics of ciprofloxacin-resistant Proteus mirabilis isolates from urine samples associated with nosocomial infection or colonisation, and identified the risk-factors for ciprofloxacin resistance. Data for patients with ciprofloxacin-resistant P. mirabilis isolates (n=13) were compared with those for randomly selected patients with ciprofloxacin-susceptible P. mirabilis isolates (n=40) who were matched by temporal occurrence as control patients. The majority of ciprofloxacin-resistant P. mirabilis isolates were multiresistant, and ciprofloxacin resistance was associated significantly with previous use of fluoroquinolones and production of extended-spectrum beta-lactamases.     

A simple and reliable method to screen isolates of Escherichia coli and Klebsiella pneumoniae for the production of TEM- and SHV-derived extended-spectrum β-lactamases

Objective: To evaluate which of 24 β-lactams used in susceptibility tests best discriminated between strains of Klebsiella pneumoniae and Escherichia coli that produce extended spectrum β-lactamases (ESBLs) from strains that produce older, more familiar, plasmid-mediated β-lactamases such as TEM-1 and SHV-1.
Methods: Susceptibility to the 24 β-lactam agents was determined by agar dilution and disk diffusion methodologies, using 27 strains of K. pneumoniae and E. coli that produced 22 different older plasmid-mediated β-lactamases and 28 strains that produced 17 different ESBLs.
Results: In general, strains that produced ESBLs were intermediate or resistant to cefpodoxime, whereas those that produced other β-lactamases were susceptible to this agent. The agar dilution test exhibited 96% sensitivity and 100% specificity in discriminating these two groups of organisms. The disk diffusion test exhibited 100% sensitivity and 96% specificity. All other β-lactam agents tested were inferior discriminators between the two groups of organisms.
Conclusions: Agar dilution and disk diffusion tests with cefpodoxime can be used to discriminate strains of K. pneumoniae and E. coli that produce ESBLs from those that produce older, plasmid-mediated β-lactamases.     

Rapid detection of enterobacteriaceae producing extended spectrum beta-lactamases directly from positive blood cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry

Bacteria that produce extended-spectrum β-lactamases (ESBLs) are an increasing healthcare problem and their rapid detection is a challenge that must be overcome in order to optimize antimicrobial treatment and patient care. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has been used to determine resistance to β-lactams, including carbapenems in Enterobacteriaceae, but the methodology has not been fully validated as it remains time-consuming. We aimed to assess whether MALDI-TOF can be used to detect ESBL-producing Enterobacteriaceae from positive blood culture bottles in clinical practice. In the assay, 141 blood cultures were tested, 13 of them were real bacteraemias and 128 corresponded to blood culture bottles seeded with bacterial clinical isolates. Bacteraemias were analysed by MALDI-TOF after a positive growth result and the 128 remaining blood cultures 24 h after the bacterial seeding. β-lactamase activity was determined through the profile of peaks associated with the antibiotics cefotaxime and ceftazidime and its hydrolyzed forms. Clavulanic acid was added to rule out the presence of non-ESBL mechanisms. Overall data show a 99% (103 out of 104) sensitivity in detecting ESBL in positive blood cultures. Data were obtained in 90 min (maximum 150 min). The proposed methodology has a great impact on the early detection of ESBL-producing Enterobacteriaceae from positive blood cultures, being a rapid and efficient method and allowing early administration of an appropriate antibiotic therapy.     

Multidrug resistance mediated by co-carriage of extended-spectrum beta-lactamases,AmpC and New Delhi metallo-beta-lactamase-1 genes among carbapenem-resistant Enterobacteriaceae at five Indian medical centres

In this study, we evaluated the coexistence of extended-spectrum beta-lactamases (ESBL), AmpC and New Delhi metallo-beta-lactamase-1 (NDM-1) genes among carbapenem-resistant Enterobacteriaceae (CRE) recovered prospectively from patients at multiple sites. The study included 285 CRE strains from 2782 Gram-negative Bacilli collected from multiple centres during 2007–2010, of which 87 were characterised. Standard and reference laboratory methods were used for resistance determination. Detection of bla_NDM-1, bla_AmpC, bla_TEM, bla_SHV and bla_CTX-M was done by polymerase chain reaction. High levels of antimicrobial resistance observed among study isolates. Co-carriage of ESBLs, AmpC and NDM-1 was 26.3%. Nosocomial origin among the co-carriage isolates was 64.3%, with 9.2% associated mortality.     

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.     

产超广谱β-内酰胺酶大肠埃希菌感染分布及危险因素分析

目的分析近两年来深圳市第三人民医院产超广谱β-内酰胺酶(ESBLs)-大肠埃希菌(ECO)的来源标本类型、病区分布,以及危险因素,为医院感控和临床抗感染治疗提供细菌学依据。方法收集该院住院患者检出的非重复ECO 443株,采用phoenix100系统进行菌种鉴定和药敏实验,并对产ESBLs-ECO进行双纸片协同试验确证,对产ESBLs-ECO感染的危险因素进行统计分析。结果 443株ECO中产ESBLs-ECO为115株,占26.0%;产ESBLs-ECO菌株主要分离自痰液、尿液和血液标本,病区分布以结核病区、儿科、肝病区和感染科为主,分别占20.9%、13.9%、12.2%和8.7%。男性、外科手术和第三代头孢菌素用药史是产ESBLs-ECO感染的独立危险因素。结论该院产ESBLs-ECO检出率较高,医院应根据危险因素制订干预措施,特别应重点关注男性患者,规范外科手术操作及消毒,限制使用第三代头孢菌素,减少院内产ESBLs-ECO的发生和传播。     

血流感染产超广谱 β-内酰胺酶大肠埃希菌的药敏结果及感染危险因素分析

目的　分析血流感染产超广谱 β -内酰胺酶（ ESBLs）大肠埃希菌的药敏特点和危险因素,为临床诊疗和预防提供依据。方法　回顾性分析商洛市中心医院 111例大肠埃希菌血流感染的药敏结果和临床特点,根据大肠埃希菌是否产 ESBLs分为 ESBLs组和非 ESBLs组,分析两组药敏结果差异,并探讨产 ESBLs大肠埃希菌血流感染的危险因素。结果　111株大肠埃希菌中, 81株产 ESBLs ,占 73.0%。对 21种常用抗生素进行药敏实验, ESBLs组的耐药率明显高于非 ESBLs 组,敏感率低于非 ESBLs组。ESBLs组对氨苄西林、头孢唑林、头孢曲松、头孢哌酮和头孢噻肟的耐药率超过 85%,两组对阿米卡星、亚胺培南、美罗培南和哌拉西林 /他唑巴坦的敏感率均超过 90%。两组间比较阿莫西林 /克拉维酸、四环素、哌拉西林 /他唑巴坦、亚胺培南、美罗培南和阿米卡星六种药物的耐药率和敏感率差异均无统计学意义 (χ2＝ 0.000~3.700,均 P>0.5)。单因素分析显示各种置管、β -内酰胺类或酶抑制剂复合制剂使用、并发高血压三个因素在两组间差异有统计学意义 (χ2＝ 8.066,P＝ 0.005;χ2＝ 8.828,P＝ 0.003;χ2＝ 4.022,P＝ 0.045)。多因素分析显示 β -内酰胺类或酶抑制剂复合制剂使用、各种置管是产 ESBLs大肠埃希菌血流感染的独立危险因素 (χ2＝ 6.703, P＝ 0.001;χ2＝ 4.511,P＝ 0.034)。结论　该院血流感染大肠埃希菌 ESBLs检出率和耐药率较高。患者使用 β -内酰胺类或酶抑制剂复合制剂治疗和各种置管时需警惕血流感染产 ESBLs大肠埃希菌的发生。