Prevalence of metallo-beta-lactamase among Pseudomonas aeruginosa and Acinetobacter baumannii in a Korean university hospital and comparison of screening methods for detecting metallo-beta-lactamase

To identify the metallo-beta-lactamases (MBLs) prevalent in Korea, a total of 130 clinical isolates of Pseudomonas aeruginosa and Acinetobacter baumannii (99 P. aeruginosa and 31 A. baumannii) with a reduced susceptibility to imipenem (IPM) and/or ceftazidime (CAZ) was subjected to PCR analyses with primers specific to bla(IMP-1), bla(VIM-1), and bla(VIM-2). In addition, inhibitor-potentiated disk diffusion methods (IPD) using two kinds of substrate-inhibitor combinations (ceftazidime-2-mercaptopropionic acid (2MPA) and imipenem-EDTA) were investigated. Thirty-three isolates (29 P. aeruginosa and 4 A. baumannii) carried bla(VIM-2) and two P. aeruginosa isolates harbored bla(IMP-1). The enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) pattern revealed that many of the VIM-2-producing P. aeruginosa isolates were clonally related, whereas the A. baumannii isolates were diverse. The inhibitor-potentiated disk diffusion test using imipenem-EDTA was highly sensitive and specific for detecting the VIM-2 producer. These results suggest that VIM-2 is an important MBL in P. aeruginosa and A. baumannii in the Korean hospital of this study and that the IMP-1-producing P. aeruginosa has also emerged. Screening for MBLs and strict infection control for these isolates will contribute to prevent further spread of resistance.     

Pathogens and drug-resistance of hospital-acquired pneumonia in an EICU in Tianjin,China

Objective: Observing the pathogens and drug-resistance within hospital-acquired pneumonia (HAP) in an emergency intensive care unit (EICU) to provide a reference for clinically reasonable use of antibiotics. Methods: Sixty-two patients with HAP in Tianjin Medical University General Hospital from January 2017 to May 2019 were analyzed retrospectively. Bacterial identification and susceptibility were reviewed. Results: One hundred and thirty-seven strains of pathogenic bacteria were isolated from 62 patients, with 97.1% Gram-negative and only 2.9% Gram-positive. There were also six fungal isolates. The most common pathogens were Acinetobacter baumannii, accounting for 30.8% of all isolates, followed by Klebisella spp, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Escherichia coli. Acinetobacter baumannii was poorly susceptible to piperacillin-tazobactam, cefepime, Amoxicillin+clavulonic acid, ciprofloxacin. However, the isolates were sensitive to Tigecycline, so as the isolates of Klebisella spp. Pseudomonas aeruginosa was mostly sensitive to Amikacin, followed by Tobramycin. All of the isolates of Staphylococcus aureus were susceptible to Linezolid, Tigecycline and Vancomycin. Conclusions: Gram-negative bacteria especially Acinetobacter baumannii, are the main pathogens for HAP in the observed EICU. The variety of pathogens should be monitored at regular intervals to improve resistance issues and therapeutic effect.     

肺结核合并非发酵菌下呼吸道感染的临床特征及耐药性分析

目的了解肺结核患者合并非发酵菌下呼吸道感染的临床特征及耐药性,为临床合理使用抗菌药物提供依据。方法采用ATB全自动细菌鉴定仪,对临床分离菌株进行菌种鉴定,用K．B法对非发酵菌做药物敏感试验。结果从肺结核患者下呼吸道标本中共分离非发酵菌156株,其中铜绿假单胞菌最多,占46．5％,其次为鲍曼不动杆菌和嗜麦芽寡养单胞菌,分别占37．8％和9．6％。药敏试验显示5种非发酵菌对多种抗生素均表现为高度耐药或多重耐药,高于相关研究,差异有统计学意义（P≤0．05）。结论肺结核患者肺部感染非发酵菌的分离率较高,多重耐药现象严重,临床应重视非发酵菌感染和耐药性监测。     

Etiology of severe hospital infections in intensive care units and antibiotic resistance of pathogens]

The leading pathogens of severe infections in intensive care units were the following: respiratory tract infections--bacteria of the famility of Enterobacteriaceae (33.8%), Pseudomonas spp. (24.9%), Acinetobacter spp. (18.1%), Staphylococcus aureus (16.0%), blood flow infections--coagulase negative staphylococci (33.6%), S. aureus (26.1%), Enterobacteriaceae (17.6%), wound infections--Enterobacteriaceae (35.7%), coagulase negative staphyloccocci (17.8%), Pseudomonas spp. (14.3%). As for various species of Enterobacteriaceae, susceptibility was preserved in 91-100% of the isolates to meropenem, in 72-100% to cefoperazone/sulbactam, in 51-65% to cefepime, in 72-86% to amikacin, and in less than 50% to cephalosporins and fluoroquinolones. As for P.aeruginosa, 28% of the isolates was resistant to all the antibacterials, except polymyxin. The highest susceptibility to cefoperazone/sulbactam and meropenem was revealed in the isolates of Acinetobacter baumannii. Oxacillin resistance was detected in 64.9% of the S.aureus isolates. The oxacillin resistance as a rule was associated with resistance to macrolides, aminoglycosides and fluoroquinolones. As for coagulase negative staphylococci, oxacillin resistance was stated in 75.6% of the isolates. All the isolates of the Staphylococcus spp. preserved their susceptibility to vancomycin and linezolid.     

Resistance epidemiology of gramnegative nonfermenting pathogens of nosocomial infections in intensive care units and surgical departments]

Etiological structure, patterns and antibiotic resistance mechanisms of gramnegative nonfermenting pathogens of nosocomial infections isolated from patients in intensive care units and surgical departments were investigated. One hundred thirty one clinical isolates, including 86 (65.6%) isolates of Pseudomonas aeruginosa and 45 (34.4%) isolates of Acinetobacter baumannii were tested. Carbapenems and cefoperazone/sulbactam showed the highest activity against the tested isolates. Eleven carbapenem resistant strains of P. aeruginosa were detected. The strains were found to possess genetic determinants of the VIM group encoding metal beta-lactamases.     

铜绿假单胞菌氨基糖苷16SrRNA甲基化酶基因分析

目的调查215株湖州地区临床分离铜绿假单胞菌对氨基糖苷类抗生素的耐药性和16S rRNA甲基化酶基因分布情况。方法收集2011年1月至2012年12月湖州地区临床分离铜绿假单胞菌215株,琼脂稀释法测定5种氨基糖苷类抗菌药物（庆大霉素、阿米卡星、妥布霉素、伊帕米星、奈替米星）的MIC值;PCR检测armA、rmtA、rmtB、rmtC、rmtD和npmA六种氨基糖苷类16S rRN甲基化酶基因,序列分析明确基因型。测定产16S rRNA甲基化酶菌株对常见抗菌的敏感性,并检测碳青霉烯耐药株产碳青霉烯酶情况。结果铜绿假单胞菌对异帕米星敏感率最高为81.4%,对5种氨基糖苷类抗生素全部耐药的22株菌株中,17株检出armA基因;未发现其他16S rRNA甲基化酶基因阳性菌株。17株armA阳性菌株对碳青霉烯类抗生素耐药5株（耐药率为29.4%）,对头孢他啶、头孢吡肟、哌拉西林/他唑巴坦、环丙沙星耐药率均超过40%。5株碳青霉烯耐药菌株中检测到2株产VIM-2型金属碳青霉烯酶。结论铜绿假单胞菌对氨基糖苷类抗生素耐药率高,检测到16S rRNA甲基化酶基因armA。产16S rRNA甲基化酶铜绿假单胞菌耐药性强,部分菌株同时产金属碳青霉烯酶,给临床抗感染治疗及院内感染控制带来挑战。     

高龄患者血液感染常见革兰阴性杆菌及其耐药性分析

目的分析本院80~100岁高龄患者血液感染常见革兰阴性杆菌的种类及其耐药状况,为本院合理使用抗生素提供依据。方法采用BacT/Alert 3D血培养仪对血液标本进行阳性鉴定;VITEK-2Compact全自动微生物鉴定仪进行鉴定;K-B纸片扩散法对抗菌药物进行敏感性测定;使用WHONET 5.4分析软件分析数据。结果本院高龄患者血液培养阳性标本中共分离出革兰阴性杆菌108株,以肠杆菌科细菌为主,其次为非发酵菌,前者主要为大肠埃希菌52株(48.15%)和肺炎克雷伯菌37株(34.26%),后者主要包括铜绿假单胞菌10株(9.26%)和鲍曼不动杆菌8株(7.41%)。其中大肠埃希菌和肺炎克雷伯菌对亚胺培南的耐药率分别为1.92%和13.51%,两者对氨苄西林、氨苄西林/舒巴坦、头孢唑林、头孢呋辛的耐药率均高于50.00%;铜绿假单胞菌和鲍曼不动杆菌对亚胺培南的耐药率分别为20.00%和25.00%,后者对其他抗菌药物的耐药率均高于前者。结论碳青酶烯类抗生素可作为本院高龄患者常见革兰阴性杆菌所致血液感染的首选药物;但在治疗中应考虑细菌的耐药特点及患者的代谢特点合理选择抗生素。     

非免疫抑制患者医院获得性肺炎及呼吸机相关肺炎病原菌组成及耐药性分析

目的分析非免疫抑制患者医院获得性肺炎及呼吸机相关肺炎临床特征、病原菌组成及耐药性,指导临床诊断及合理使用抗菌素。方法回顾性分析46例前瞻性观察诊断的非免疫抑制患者医院获得性肺炎及呼吸机相关肺炎临床及微生物学资料。结果平均起病时间为人院后（14．3±13．2）d,最常见基础疾病依次为脑血管意外（16／46）,慢性肺部疾病（13／46）和糖尿病（5／46）。培养阳性率58．7％,最常见细菌依次为鲍曼不动杆菌（8／27）、铜绿假单胞菌（6／27）、阴沟肠杆菌（3／29）及金黄色葡萄球菌（3／29）。80．4％患者入院72h内使用过抗生素,初始经验性治疗最常使用的抗菌素依次为头孢菌素（29／46）、碳青霉烯类（9／46）、糖肽类（5／46）。8株鲍曼不动杆菌对头孢哌酮／舒巴坦中介MIC〉32mg／L,对其他抗生素耐药;2株铜绿假单胞菌对美罗培南高度耐药MIC=128mg／L。结论非免疫抑制患者医院获得性肺炎及呼吸机相关肺炎多发生在有脑血管疾病及慢性肺疾病老年患者,我院非免疫抑制患者医院获得性肺炎及呼吸机相关肺炎最常见的病原菌多药耐药鲍曼不动杆菌,铜绿假单胞菌对碳青霉烯类耐药率较高。应优化医院获得性肺炎及呼吸机相关肺炎初始抗生素使用。     

Oligonucleotide probes specific for the genus Salmonella and for Salm. typhimurium

The Crystal Enteric/Nonfermenter (E/NF) identification kit (Becton Dickinson Microbiology Systems, USA) was evaluated using water-derived bacterial isolates and results compared to those obtained by the API 20E system (BioMérieux, UK). Both the E/NF and 20E systems correctly identified 93% of the Enterobacteriaceae reference cultures. Both systems agreed in the identification of 64·9% of environmental isolates. The E/NF system gave a positive identification to 88·0% of isolates and the 20E to 79·5% of isolates. The principal tests which gave differing reactions between the two systems were arginine dihydrolase, lysine decarboxylase, urease and citrate utilization.     

N-butanoyl-L-homoserine lactone (BHL) deficient Pseudomonas aeruginosa isolates from an intensive care unit

Acylated homoserine lactones (AHLs) are self-generated diffusible signal molecules that mediate population density dependent gene expression (quorum sensing) in a variety of Gram-negative bacteria, and several virulence genes of human pathogens are known to be controlled by AHLs. In this study, strains of Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae, isolated from intensive care patients, were screened for AHL production by using AHL responsive indicator strains of Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NT1. Positive reactions were recorded for all 50 isolates of P. aeruginosa and 10 isolates of Acinetobacter baumannii with Agrobacterium tumefaciens NT1. Surprisingly, most P. aeruginosa isolates gave negative results with C. violaceum CV026 in contrast to previous reports. This suggests that the new isolates of P. aeruginosa either failed to make short chain AHLs or the level of the signal molecule is very low.     

重症监护病房革兰阴性菌分布及耐药性分析

目的：了解我院重症监护病房革兰阴性菌的分布和耐药情况。方法：WHONET5.6分析585例的革兰阴性菌的细菌培养和药物敏感试验结果。结果：585例革兰阴性菌标本中,排名前五位的是铜绿假单胞菌菌152株（25.98%）,鲍曼不动杆菌111株（18.97%）,肺炎克雷伯菌98株（16.75%）,大肠埃希菌49株（8.38%）,洋葱伯克霍尔德菌39株（6.67%）。这五种病原菌对14中抗生素的药敏试验发现,除了对头孢哌酮/舒巴坦耐药率较低外,对其他抗生素都有不同程度的耐药。结论：革兰阴性菌在感染的病原菌中仍占主要地位,耐药性也很严重,应及时检测病原菌变化及耐药趋势,指导临床合理使用抗生素。     

神经外科颅内出血患者下呼吸道感染病原菌的耐药性监测

目的了解神经外科重症监护室（NICU）颅内出血患者下呼吸道感染病原菌的种类及耐药情况,为临床合理用药提供依据。方法对2010年1月至2011年1月颅内出血的患者,其下呼吸道感染病原菌的种类及耐药性进行回顾性分析。结果分离出的374例病原菌中以革兰阴性杆菌为主,占81．8％,革兰阳性球菌占4．0％,真菌占14．2％。分离率较高的细菌依次为鲍曼不动杆菌、铜绿假单胞菌、肺炎克雷伯菌、嗜麦芽窄食单胞菌、金黄色葡萄球菌。其中,产超广谱β-内酰胺酶（ESBLs）的肺炎克雷伯菌的检出率为50．0％;耐甲氧西林金黄色葡萄球菌（MRSA）的检出率为73．3％。鲍曼不动杆菌和铜绿假单胞菌对丁胺卡那、妥布霉素、多粘菌素B有较好的敏感性;而金黄色葡萄球菌对复方新诺明、呋喃妥因、万古霉素耐药率较低。结论NICU颅内出血患者下呼吸道感染以多重耐药的革兰阴性杆菌为主,临床应根据药敏结果合理用药,控制和减少感染的发生。     

泌尿系感染病原菌分布及耐药性分析

目的了解深圳市人民医院泌尿系感染病原菌的分布及耐药性,为临床医师合理使用抗菌药物提供科学依据。方法对655株泌尿系统感染病原菌进行常规鉴定,用k-B法或ATB-FUNGUS 3对其进行药敏试验。结果病原菌构成比前5位分别为大肠埃希菌（37.9%）、假丝酵母（18.0%）、肠球菌（13.1%）、肺炎克雷伯菌（6.6%）、铜绿假单胞菌（6.3%）。病原菌对各种抗菌药物产生了不同程度的耐药,肺炎克雷伯菌、铜绿假单胞菌对亚胺培南和美罗培南的耐药率为14.3%～26.8%。结论深圳市人民医院泌尿系感染病原菌主要以大肠埃希菌、假丝酵母和肠球菌等为主,病原菌对抗菌药物已产生了一定的耐药性,应加强监测与控制。     

尿培养中病原菌分布及耐药性分析

目的研究大连市中心医院2007年1月至2012年9月尿培养中常见病原菌（真菌除外）的分布及其耐药性,为临床治疗尿路感染提供诊断及用药依据。方法采用MicroScan—Walkaway40全自动微生物鉴定药敏分析仪和ATBExpression自动细菌鉴定仪及K—B纸片法药敏试验,应用WHONET5．4软件对结果进行回顾性统计分析。结果五年间尿培养中共分离出病原菌1012株（真菌除外）,其中革兰阴性菌802株（79．2％）,主要是大肠埃希菌538株（53．2％）、肺炎克雷伯菌95株（9．5％）、铜绿假单胞菌51株（5．1％）、奇异变形杆菌30株（2．9％）、鲍曼不动杆菌26株（2．6％）。革兰阳性菌210株（20．8％）,主要是粪肠球菌86株（8．6％）,屎肠球菌83株（8．2％）,凝固酶阴性葡萄球菌21株（2．1％）,金黄色葡萄球菌13株（1．3％）。抗生素敏感试验中碳青霉烯类（亚胺培南及美洛培南）对肠杆菌科细菌大肠埃希菌、肺炎克雷伯菌及奇异变形杆菌抗菌活性最强,无耐药菌株,对非发酵菌中铜绿假单胞菌和鲍曼不动杆菌耐药率为30％～40％,革兰阳性菌对糖肽类（万古霉素、替考拉宁）和利奈唑胺等抗菌药物高度敏感。结论应当根据主要易感菌种类及其抗生素敏感试验结果指导临床合理使用抗生素。     

Anomalies in species identification of enterococci from veterinary sources using a commercial biochemical identification system

AIMS: A commercial biochemical panel ID kit was used to identify presumptive enterococci isolates of veterinary or agricultural origin obtained during different steps of culture. METHODS AND RESULTS: Fifty isolates identified as enterococci using a genus PCR assay were tested for genus and species identification using the BBL Crystal Identification Gram-Positive ID kit (Becton Dickinson, Sparks, MD, USA). Following sub-culture of the isolates three times, 59% agreement with the original panel ID was obtained. After four and six sub-cultures, percentage agreement increased to 61 and 64%, respectively. Nineteen of the 50 cultures were identified as both Enterococcus faecalis and E. faecium. CONCLUSIONS: As a result of the variability between speciation of isolates following re-culture, additional methods for speciation are warranted. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that the identification of the genus and species of non-human enterococcal isolates can vary greatly during successive passages when using this kit.     

Microbiological surveillance of the surgical intensive care unit in Zagreb--a pivot for guideline-based therapy of severe sepsis

The aim of this retrospective study was to create guidelines for therapy of severe sepsis in surgical intensive care unit (ICU) for unknown causative agent based on antimicrobial susceptibility of causative bacteria. Seventy-four patients with severe sepsis from surgical ICU in 2003.-2005. were included in study. Their clinical and microbiological data were analyzed from the medical records. Antimicrobial susceptibility of the strains isolated from the blood-culture was tested by disk diffusion method according to CLSI (Clinical Laboratory Standard Institution). APACHE II score was used to predict the severity of illness. Statistical significance difference between results was tested by Mann-Whitney test and chi2 test. Important problem remained type of sepsis: mono-agent sepsis presented less therapeutic problem than sepsis caused with two or more agents (mixed sepsis). Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Acinetobacter baumannii were predominant causative agents in both type of sepsis. There was remarkable increase of A. baumannii prevalence in 2005 compared to 2004 and to 2003. There was also decrease of MRSA prevalence in 2004 and 2005 compared to 2003. P. aeruginosa were the predominant causative agents in 2004. MRSA displayed good susceptibility to vancomycin and linezolide, whereas P. aeruginosa showed excellent susceptibility to ceftazidime and carbapenems. A. baumannii, third predominant causative agent, exhibited excellent susceptibility to ampicillin+ sulbactam and carbapenems. The recommended therapy is empirical and should cover all important pathogens.     

Susceptibility to chemotherapeutics and the occurrence of metallo-beta-lactamases in hospital Pseudomonas aeruginosa strains

The aim of the study was evaluation of susceptibility of Pseudomonas aeruginosa strains isolated from patients hospitalized in different wards of Rydygier's Hospital in Krakow in 2005. Bacteria were identified on the basis of typical morphology confirmed by Gram-staining microscopy and by biochemical tests--ID 32 GN strips using ATB system (bioMerieux, France). The susceptibility of all isolates to a panel of antimicrobial agents was performed using disk diffusion method. The highest in vitro activity against clinical strains demonstrated ceftazidime (88.6% of susceptible strains) while the lowest in vitro activity against clinical strains demonstrated imipenem (50.4% of susceptible strains). It was also observed that 40.2%(53) of strains were resistant to meropenem and imipenem. Carbapenem resistant P aeruginosa strains were tested for MBL production. We performed disk synergy test for MBL detection with EDTA, 2-MPA and ceftazidime, imipenem. The presence of a distorted inhibition zone was interpreted as a positive result for MBL production. Positive results of disk synergy tests were confirmed by Etest MBL strips. Metalo-beta-lactamases were detected in 13 isolates resistant to carbapenems.     

Study of mycoloyl transferase transport across the cell envelope of Corynebacterium glutamicum

A bla(VIM-2) metallo-beta-lactamase determinant, identical to that previously identified in Pseudomonas aeruginosa COL-1 isolate from a French hospital, was detected on a 28-kb plasmid carried by a nosocomial isolate of P. aeruginosa from Verona, Italy. In this plasmid the bla(VIM-2) determinant was inserted into a class 1 integron of original structure, named In72, that contains a partially deleted intI1 integrase gene and two gene cassettes. The first cassette carries an aacA4 aminoglycoside acetyl transferase determinant. The second cassette carries a bla(VIM-2) determinant followed by a partially deleted attC site. The structure of In72 was notably different from that of In56, the bla(VIM-2)-containing integron found in the COL-1 isolate, revealing the existence of molecular heterogeneity among bla(VIM-2)-containing integrons in clinical isolates of P. aeruginosa from Europe.     

Identification and Antimicrobial Susceptibility Testing of <Emphasis Type="Italic">Staphylococcus vitulinus</Emphasis> by the BD Phoenix Automated Microbiology System

This study evaluated the performance of the BD Phoenix system for the identification (ID) and antimicrobial susceptibility testing (AST) of Staphylococcus vitulinus. Of the 10 S. vitulinus isolates included in the study, 2 were obtained from the Czech Collection of Microorganisms, 5 from the environment, 2 from human clinical samples, and 1 from an animal source. The results of conventional biochemical and molecular tests were used for the reference method for ID, while antimicrobial susceptibility testing performed in accordance with Clinical and Laboratory Standards Institute recommendations and PCR for the mecA gene were the reference for AST. Three isolates were incorrectly identified by the BD Phoenix system; one of these was incorrectly identified to the genus level, and two to the species level. The results of AST by the BD Phoenix system were in agreement with those by the reference method used. While the results of susceptibility testing compared favorably, the 70% accuracy of the Phoenix system for identification of this unusual staphylococcal species was not fully satisfactory.     

老年气管插管患者下呼吸道感染细菌分布及 耐药性分析

目的研究老年气管插管患者下呼吸道感染的病原菌分布及耐药情况,为临床插管前预防性经验用药提供参考。方法回顾性分析2014-2016年上海市虹口区江湾医院老年气管插管患者的病原菌分布及耐药性情况。结果 560例标本中共检出177株致病菌,其中革兰阴性杆菌121株(68.36%),以肺炎克雷伯菌、铜绿假单胞菌为主;除鲍曼不动杆菌/溶血不动杆菌外,其他革兰阴性杆菌对亚胺培南、美罗培南敏感性均较高。革兰阳性球菌检出52株(29.38%),以金黄色葡萄球菌为主(其中MRSA 37株),对万古霉素敏感性较高。另外分离到真菌4株。结论气管插管患者下呼吸道感染致病菌以肺炎克雷伯菌、铜绿假单胞菌、金黄色葡萄球菌为主。在临床应用中,应根据本地区、本医院的病原菌分布状况和细菌耐药情况,给予适当药物,预防感染。