Hospital outbreak caused by a carbapenem-resistant strain of Acinetobacter baumannii: patient prognosis and risk-factors for colonisation and infection

Between October 2001 and August 2002, 30 hospital patients became infected or colonised by a multiresistant (including to carbapenems) epidemic strain of Acinetobacter baumannii (AbMR) in a hospital outbreak. This study analysed the risk-factors associated with acquisition of this epidemic strain and investigated the prognosis of patients infected by AbMR, with the aim of elucidating factors which lead to mortality. A case-control study of the acquisition of AbMR in patients infected or colonised in the hospital outbreak was performed. Independent risk-factors leading to death were studied by logistic regression analysis. Multivariate analysis of the risk-factors for colonisation/infection with AbMR revealed an independent association with the presence of an arterial catheter (OR, 1.13; 95% CI, 1.03-1.25) and administration of imipenem as monotherapy (OR, 11.12; 95% CI, 2.33-53.09). Multivariate analysis of the prognostic features leading to mortality revealed a significant association with hypotension or shock (OR, 24.63; 95% CI, 1.56-387.56) at the time of bacterial isolation.     

鲍氏不动杆菌致慢性阻塞性肺疾病患者肺部感染临床及耐药性分析

目的 探讨慢性阻塞性肺疾病(COPD)患者肺部鲍氏不动杆菌感染的临床特点和耐药情况.方法 对78例COPD患者肺部鲍氏不动杆菌感染的临床表现及药敏情况进行回顾分析.结果 药物敏感性测定提示该菌对头孢哌酮/舒巴坦耐药率最低,为14.9%,其次为亚胺培南和美罗培南,分别是24.8%和28.2%;对氨苄西林、头孢他啶,头孢吡肟、哌拉西林、左氧氟沙星、莫西沙星、阿米卡星、氨曲南和替卡西林/克拉维酸有较高耐药率,为48.5%～74.8%.结论 COPD患者肺部鲍氏不动杆菌感染与年老体弱,广谱抗菌药物及激素应用、呼吸道侵入性操作及呼吸机使用有关,临床表现无特异性,耐药严重,病死率高,应注意预防.     

Alert surveillance of intensive care unit-acquired Acinetobacter infections in a Sicilian hospital

The epidemiological impact of Acinetobacter baumannii nosocomial infections in a Sicilian intensive care unit (ICU) was investigated to determine the Acinetobacter-specific infection rates, to estimate the preventable proportion of Acinetobacter infections, i.e., those resulting from cross-transmission, and to investigate the molecular epidemiology of antimicrobial resistance in Acinetobacter. The impact of Acinetobacter nosocomial infection in the ICU was determined to be 3.0 new cases per 100 admissions. Site-specific rates confirmed that ICU-acquired pneumonia was the most important infection type. The incidence rate, adjusted by the number of patient-days, was 3.3 infections/1000 patient-days. The estimated preventable proportion of A. baumannii nosocomial infections in the ICU was 66.7%. A class 1 integron, characterised by its gene cassette content, was present in all A. baumannii isolates of four different pulsed-field gel electrophoresis types, and was associated significantly with clones implicated in cross-transmission episodes. Furthermore, the same integron was detected in two genetically distinct isolates responsible for recurrent infection in the same patient, suggesting the occurrence of horizontal gene transfer in vivo. Even in an endemic setting with low infection rates, spread of A. baumannii was caused mainly by infection control shortcomings that require appropriate surveillance and control policies.     

多重耐药鲍曼不动杆菌相关耐药基因检测分析

目的为了解多重耐药鲍曼不动杆菌β-内酰胺酶（BLA）基因、氨基糖苷类修饰酶（AMFs）基因、消毒剂与磺胺类耐药基因（qacE△1-sul1）和1类整合子酶基因（intl1）存在情况。方法对2005年1—6月份临床分离的31株多重耐药菌株（耐哌拉西林、第三代头孢菌素、环丙沙星和阿米卡星），应用聚合酶链反应及序列分析方法分析其BLA、AMEs、qacE△1．sull和intl1基因类型。结果31株多重耐药鲍曼不动杆菌对多黏菌素B敏感，有3株（9．7％）对受试的其他18种抗菌药物均耐药。19株（61．3％）检出了β-内酰胺酶基因，其中TEM、PER、DHA阳性率分别为61．3％、19．4％、3．2％，未检出SHV、OXA-23、OXA-24、GES、IMP和VIM等基因。25株（80．6％）检出氨基糖苷类修饰酶基因，其中aac（3）-I、aac（6’）-I、ant（3”）-I、ant（2”）-I、aac（3）-Ⅱ、aac（6’）-Ⅱ阳性率分别为67．7％、45．2％、29．0％、22．6％、9．7％、3．2％。qacE△A1-sul1、intl1阳性率分别为80．6％、58．1％。分离株常见的基因组合是TEM＋qacE△1-sul1＋intl1和TEM＋PER＋qacE△1-sull＋intl1，分别占25．8％和19．4％。分离株AMEs的常见的基因组合是aac（3）-I＋aac（6’）-I和nnc（3）-I＋aac（6’）-I＋ant（2”）-I，分别占19．4％和12．9％。结论临床分离的多重耐药鲍曼不动杆菌TEM、nnc（3）-I、nnc（6’）-I、ant（3”）-I、ant（2”）-I、qacE△1-sul1和intl1基因携带率高。     

Synergic in-vitro activity of imipenem and sulbactam against Acinetobacter baumannii

The interaction between sulbactam and imipenem was evaluated with four clinical isolates of Acinetobacter baumannii, including two isolates resistant to imipenem, one of which produced IMP-1 metallo-beta-lactamase. Two isolates (one of which was imipenem-resistant) were sulbactam-resistant by undefined mechanisms. MICs were determined by standard broth microdilution methods. Time-kill assays with imipenem and sulbactam, alone or in combination at 0.5 x MIC and 1 x MIC, showed a synergic effect in all four isolates of A. baumannii after incubation for 0, 4, 8 and > 24 h at 35 degrees C.     

Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.     

Molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii in a university hospital in Italy

This study investigated the molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii that occurred between June 2003 and June 2004 in a tertiary-care hospital in Naples, Italy. A. baumannii was isolated from 74 patients, of whom 38 were infected and 36 were colonised. Thirty-three patients had ventilator-associated pneumonia, three had hospital-acquired pneumonia, and two had sepsis. Genotypic analysis of 45 available A. baumannii isolates revealed two distinct pulsed-field gel electrophoresis (PFGE) patterns. Of these, PFGE pattern 1 was represented by isolates from 44 patients and was identical to that of an epidemic A. baumannii clone isolated in another hospital of Naples during 2002. All A. baumannii isolates of PFGE type 1 showed identical multiresistant antibiotypes, characterised by resistance to all antimicrobial agents tested, including carbapenems, with the exception of colistin. In these isolates, inhibition of OXA enzymes by 200 mM NaCl reduced the imipenem MIC by up to four-fold. Molecular analysis of antimicrobial resistance genes showed that all A. baumannii isolates of PFGE type 1 harboured a class 1 integron containing the aacA4, orfX and bla(OXA-20) gene cassettes, an ampC gene and a bla(OXA-51)-like allele. Moreover, a bla(OXA-58)-like gene surrounded by the regulatory elements ISAba2 and ISAba3 was identified in a 30-kb plasmid from A. baumannii isolates of PFGE type 1, but not PFGE type 2. Thus, selection of a single A. baumannii clone producing an OXA-58-type carbapenem-hydrolysing oxacillinase was responsible for the increase in the number of A. baumannii infections that occurred in this hospital.     

Carbapenem-resistant and OXA-23-producing Acinetobacter baumannii isolates in the United Arab Emirates

Five carbapenem-resistant Acinetobacter baumannii isolates, collected from the United Arab Emirates in 2006, were investigated to identify the mechanism(s) responsible for carbapenem resistance. Genotyping was performed by pulsed-field gel electrophoresis, and the location of the bla _OXA-23 gene was determined by using the endonuclease I Ceu I technique and mating-out assays. The four isolates in which the bla _OXA-23 gene was located on the chromosome within a Tn 2006 composite transposon were clonally related. The single non-clonally related isolate harboured the bla _OXA-23 gene on a 70-kb transferable plasmid. This study reports on the dissemination of OXA-23-producing A. baumannii isolates in the Middle East.     

1起ICU耐碳青霉烯类 鲍曼不动杆菌感染暴发的流行病学调查

[摘要]　目的?通过对我院ICU 9例耐碳青霉烯类鲍曼不动杆菌（carbapenem-resistant Acinetobacter baumannii, CRAB）感染者进行流行病学调查,探讨CRAB感染暴发的危险因素。方法?回顾分析2019年3月17日—4月12日我院ICU收治的9例CRAB感染者的临床资料及流行病学史,应用肠杆菌科基因间重复一致序列聚合酶链式反应技术（enterobacterial repetitive intergenic consensus-polymerase chain reaction, ERIC-PCR）分析其同源性,监测ICU环境卫生学情况。结果?我院ICU A4、A6、B3及C2床患者临床样本检出的CRAB为同一疑似克隆株;B5、C1床患者样本检出的CRAB为同一疑似克隆株;B2、B2加床患者临床样本检出的CRAB为同一疑似克隆株。通过环境卫生学监测,分别从病房的空气滤网、床栏、呼吸机按钮和护士手等部位分离出50株CRAB,其中23份样本检出与患者有相同耐药谱的CRAB。ERIC-PCR结果显示,9例临床分离菌株与25例环境菌株为克隆株。手术、气管插管和前期接受抗菌药物治疗是CRAB感染的危险因素。结论?ICU患者、工作人员感控管理不到位以及空气、环境和ICU医务人员手卫生的清洁消毒措施不严格可能是此次CRAB感染传播的原因,为了减少此类医院感染事件的发生,建议加强对ICU患者与工作人员管理、加强环境及物体表面的彻底消毒、提高手卫生依从性。     

广州市儿童和青年新型冠状病毒Delta变异株感染患者临床特征

 目的 探讨儿童和青年新型冠状病毒（SARS-CoV-2） Delta变异株患者的临床特征。方法 选取广州医科大学附属市八医院2021年5月21日—6月18日收治的SARS-CoV-2 Delta突变株感染者,根据年龄分为儿童组（2~14岁）和青年组（15~35岁）,比较两组患者临床、实验室指标及影像学的差异。结果 儿童组21例,青年组24例,两组均无重症患者。儿童以家庭聚集性发病为特征,青年组普通型比儿童组更常见（66.7% VS 33.3%,P<0.05）。与青年组临床表现比较,儿童组咳嗽（33.3% VS 87.5%）、咳痰（33.3% VS 66.7%）和咽喉不适（28.6% VS 70.8%）少见（均P<0.05）,儿童发热时间更短（2.5 d VS 4 d,P<0.05）,但两组患者发热（76.2% VS 83.3%）差异无统计学意义。与青年组生化学指标比较,基线时儿童组C-反应蛋白（CRP）、血清淀粉样蛋白A （SAA）和白介素-6（IL-6）更低（均P<0.05）,但淋巴细胞（LYM）、嗜酸性粒细胞（EOS）、乳酸脱氢酶（LDH）和肌酸激酶同工酶（CK-MB）更高;第1周儿童组CRP和SAA更低,但LYM、EOS、LDH和CK-MB更高（均P<0.05）。儿童基线CK-MB和LDH升高更常见（均P<0.05）。儿童组基线时LYM减少5例（23.8%）,EOS减少3例（14.3%）,第1周LYM和EOS均恢复正常。胸部CT显示儿童组7例（33.3%）肺部感染,单侧受累为主;青年组16例（66.7%）肺部感染,双肺受累为主。儿童组SARS-CoV-2核酸转阴时间中位日数为17（12,25） d,青年组核酸转阴时间中位日数为19（15,21） d,两组患者均预后良好。结论 儿童SARS-CoV-2 Delta变异株感染以家庭聚集性发病为主要特征。与青年患者比较,儿童患者呼吸道症状、炎症反应、免疫细胞和肺损伤更轻,免疫细胞恢复更快。儿童患者基线CK-MB和LDH升高更常见,需关注急性心肌损伤的可能性。青年和儿童患者SARS-CoV-2核酸转阴时间长,需延长监测上呼吸道核酸的时间。