Risk factors for carbapenem-resistant Klebsiella pneumoniae bloodstream infection among rectal carriers: a prospective observational multicentre study

Knowledge of carbapenem-resistant Klebsiella pneumoniae (CR-KP) colonization is important to prevent nosocomial spread but also to start prompt adequate antibiotic therapy in patients with suspicion of infection. However, few studies have examined the incidence and risk factors for CR-KP bloodstream infection (BSI) among rectal carriers. To identify risk factors for CR-KP BSI among carriers, we performed a multicentre prospective matched case–control study of all adult CR-KP rectal carriers hospitalized in five tertiary teaching hospitals in Italy over a 2-year period. Carriers who developed CR-KP BSI were compared with those who did not develop subsequent BSI. Overall, 143 CR-KP BSIs were compared with 572 controls without a documented infection during their hospitalization. Multivariate analysis revealed that admission to the Intensive Care Unit (ICU) (OR, 1.65; 95% CI, 1.05–2.59; p 0.03), abdominal invasive procedure (OR, 1.87; 95% CI, 1.16–3.04; p 0.01), chemotherapy/radiation therapy (OR, 3.07; 95% CI, 1.78–5.29; p <0.0001), and number of additional colonization sites (OR, 3.37 per site; 95% CI, 2.56–4.43; p <0.0001) were independent risk factors for CR-KP BSI development among CR-KP rectal carriers. A CR-KP BSI risk score ranging from 0 to 28 was developed based on these four independent variables. At a cut-off of ≥2 the model exhibited a sensitivity, specificity, positive predictive value and negative predictive value of 93%, 42%, 29% and 93%, respectively. Colonization at multiple sites with CR-KP was the strongest predictor of BSI development in our large cohort of CR-KP rectal carriers.     

不同条件下CIM试验检测耐碳青霉烯类肠杆菌科细菌的评价

目的评估不同底物、不同孵育时间下碳青霉烯类抑制法(CIM)对肠杆菌科细菌碳青霉烯酶表型筛选能力的差异。方法分别用亚胺培南、美罗培南、厄他培南作为指示底物对120株耐碳青霉烯类肠杆菌科细菌(CRE)进行CIM试验,再以美罗培南为指示底物,分别孵育0.5、1、2、4h进行CIM试验,并采用PCR及测序技术检测菌株是否携带碳青霉烯酶相关基因。结果碳青霉烯酶耐药基因PCR检测结果显示,120株CRE中,阳性93株,阴性27株。以亚胺培南作为底物,阳性95株,阴性25株;以美罗培南作为底物,阳性87株,阴性33株;以厄他培南作为底物,阳性68株,阴性52株。与PCR结果相比,三者的灵敏度分别是98.9%(92/93),90.3%(84/93),69.9%(65/93),差异有统计学意义(χ~2=18.43,P<0.01);三者的特异度均为88.9%(24/27)。3种底物的一致率分别为96.7%,90.0%,74.2%,Kappa值分别是0.90,0.73,0.44。在4个不同孵育时间下,灵敏度分别为46.2%(43/93)、58.1%(54/93)、90.3%(84/93)和90.3%(84/93),孵育2h和0.5、1h结果相比差异有统计学意义(χ~2=27.31,P<0.05)。结论亚胺培南、美罗培南CIM试验灵敏度和一致率均高于厄他培南,可作为合适的底物,同时2h为最佳孵育时间。     

铜绿假单胞菌对碳青霉烯类抗生素5年耐药率的分析

目的探讨医院内铜绿假单胞菌(PA)对碳青霉烯类抗生素的耐药率及其变迁,以指导临床合理用药。方法采集2001-2005年病房临床分离PA共2 629株,测定对碳青霉烯类抗生素的药敏。结果对亚胺培南和美洛培南的5 a总耐药率分别是49.54%和55.57%。2001年对亚胺培南的耐药率是47.86%,2005年上升到60.59%(P<0.01)。2003年对美洛培南的耐药率是36.63%,2.005年上升到75.23%(P<0.01)。结论PA对碳青霉烯类抗生素的耐药性已十分突出,对于PA的感染,应在药敏指导下用药。碳青霉烯类抗生素的耐药性呈明显上升趋势,应该适当控制碳青霉烯类药物的使用。     

碳青霉烯类抗生素结构修饰的研究进展

碳青霉烯类抗生素广泛应用于治疗多种耐药菌引起的重症感染,按其化学结构可分为硫取代、碳取代、三稠环和多稠环类。本文综述了近年来该类药物结构修饰和构效关系的研究进展,为进一步进行新药研究提供线索。     

鲍曼不动杆菌对抗生素的耐药性监测

目的调查鲍曼不动杆菌（acinetobacter baumannii,Ab）对16种抗生素的耐药情况。方法收集我院2005年1月至2006年6月分离的288株鲍曼不动杆菌,其中社区感染株（community acquired infection,CAI）237株,医院感染株（hospital acquired infection,HAI）51株。按《全国检验技术操作规程》要求操作,用细菌鉴定仪鉴定菌种,采用K-B法做药敏试验。结果Ab对几乎所有半合成青霉素、头孢菌素、碳青霉烯类、氨基糖苷类、氟喹诺酮类均具有较高水平的耐药性,对其他酶抑制剂复合制剂亦不敏感。对亚胺培南敏感率最高为68.5%,其余抗生素的敏感率都〈54.5%。绝大多数病原菌医院内感染株的耐药率高于社区感染株,两者之间差别有统计学意义（P〈0.01）。结论近期我院经验性治疗首选阿莫西林/舒巴坦＋左氧氛沙星＋阿米卡星或SMZCO组合治疗方案。     

铜绿假单胞菌的耐药性及碳青霉烯类抗生素的研究进展

铜绿假单胞菌（Pseudomonas aeruginosa）是一种常见的医院内获得性感染致病菌，其耐药性强，耐药谱广。亚胺培南等碳青霉烯类抗生素是近年来治疗铜绿假单胞菌疗效较好的药物，但随着临床的广泛应用，铜绿假单胞菌对亚胺培南等产生了耐药性。铜绿假单胞菌对碳青霉烯类抗生素的耐药机制有β-内酰胺酶的水解、外膜通透性降低和主动外排系统的排出等，这些耐药机制之间相互协同作用而产生高度耐药。针对这些耐药机制，开发活性更高、安全性更好的碳青霉烯类抗生素显得极为迫切。本文对铜绿假单胞菌的耐药性及碳青霉烯类抗生素的研究进展进行了综述。     

Laboratory investigation of a suspected outbreak caused by Providencia stuartii with intermediate resistance to imipenem at a long-term care facility

Background

Providencia stuartii survives well in natural environment and often causes opportunistic infection in residents of long-term care facilities (LTCFs). Clinical isolates of P. stuartii are usually resistant to multiple antibiotics. The bacterium is also naturally resistant to colistin and tigecycline. Treatment of infections caused by carbapenem-resistant P. stuartii is challenging.

Clinical laboratory detection of carbapenem-resistant and carbapenemase-producing Enterobacteriaceae

Introduction: Carbapenemases, enzymes that hydrolyze carbapenem-class antimicrobials, pose serious clinical and diagnostic challenges, including their recent rapid spread among members of the Enterobacteriaceae, a family with no inherent carbapenem resistance. Currently there is no one-size-fits-all method for detecting carbapenem-resistant Enterobacteriaceae (CRE) in the laboratory, nor how to differentiate carbapenemase-producers (CP) from isolates that are carbapenem-resistant via other or combined mechanisms.

Areas covered: This article reviews definitions for CRE and CP-CRE, and discusses current phenotypic and molecular methods available to the clinical laboratory for the detection of both CP and non-CP CRE.

Expert commentary: Routine evaluation of carbapenem resistance mechanism by the routine clinical laboratory are not necessary for patient care, as clinical breakpoints best predict response. However, evaluation for carbapenemase is integral to infection control efforts, and laboratories should have the capacity to do such testing, either in house or by submitting isolates to a reference laboratory.