耐碳青霉烯革兰阴性杆菌耐药性及耐药基因blaKPC的分子特征

目的 探讨耐碳青霉烯类革兰阴性杆菌的临床耐药性及耐药基因blaKPC的分子特征。方法 分析2017年1月-2018年12月某院临床检出的耐碳青霉烯类革兰阴性杆菌。通过WHONET 5.6软件对药物敏感试验数据进行统计分析,采用PCR检测碳青霉烯耐药基因blaKPC、blaNDM、blaIMP、blaVIM、blaOXA-48,对PCR阳性产物进行DNA测序,分析耐药基因的分子结构特点。结果 共收集510株耐碳青霉烯类革兰阴性杆菌,其中耐碳青霉烯类肠杆菌科细菌（CRE）420株,耐碳青霉烯非肠杆菌科细菌90株。菌株主要来自重症监护病房（ICU）、神经外科和呼吸科,分别占60.8%、11.8%、5.3%;标本来自痰、脓性分泌物、静脉血、无菌中段尿,分别占66.9%、8.8%、8.2%、6.5%。耐碳青霉烯类革兰阴性杆菌对常用抗菌药物具有较高的耐药性。PCR结果显示,420株CRE中blaKPC、blaNDM、blaIMP的阳性率分别为54.3%（228/420）、1.2%（5/420）、1.4%（6/420）,未检测出blaVIM和blaOXA-48基因,其中肺炎克雷伯菌、产气肠杆菌、大肠埃希菌分别占携带blaKPC CRE的83.8%、11.8%、2.6%;其他少见菌种中也检出blaKPC基因。非肠杆菌科细菌中仅有2株鲍曼不动杆菌检测出blaKPC。DNA测序结果显示,174株携带blaKPC的菌株中173株检测为blaKPC-2、1株检测为blaKPC-1。结论 该地区耐碳青霉烯类革兰阴性菌以CRE为主,其中以携带blaKPC-2的肺炎克雷伯菌占绝对优势,其他菌株中也均有发现。提示临床需重点加强耐碳青霉烯类肺炎克雷伯菌的监测及预防,防控blaKPC的传播流行。     

Nosocomial outbreak by NDM-1-producing Klebsiella pneumoniae highly resistant to cefiderocol,Florence, Italy,August 2021 to June 2022

A nosocomial outbreak by cefiderocol (FDC)-resistant NDM-1-producing Klebsiella pneumoniae (NDM-Kp) occurred in a large tertiary care hospital from August 2021–June 2022 in Florence, Italy, an area where NDM-Kp strains have become endemic. Retrospective analysis of NDM-Kp from cases observed in January 2021–June 2022 revealed that 21/52 were FDC-resistant. The outbreak was mostly sustained by clonal expansion of a mutant with inactivated cirA siderophore receptor gene, which exhibited high-level resistance to FDC (MIC ≥ 32 mg/L) and spread independently of FDC exposure.     

耐碳青霉烯肺炎克雷伯菌感染的危险因素及耐药机制的研究

目的 探讨耐碳青霉烯肺炎克雷伯菌感染的危险因素及耐药机制.方法 对我院2018年6月1日-2019年5月31日57例耐碳青霉烯肺炎克雷伯菌(CRKP)感染患者和70例碳青霉烯敏感肺炎克雷伯菌(CSKP)感染患者进行回顾性分析.结果 CRKP感染患者主要分布在呼吸科31.6％(18/57)、神经内科21.1％(12/57...     

T6SS阳性CRKP临床感染特征及毒力基因分析

目的 分析T6SS阳性耐碳青霉烯类肺炎克雷伯菌(CRKP)临床感染特征, 以及其耐药、毒力基因检出率和生物膜形成能力, 为临床防控CRKP感染提供参考数据。 方法 收集2019年1月—2022年12月安徽某三甲医院临床分离的CRKP菌株及患者资料, PCR法检测T6SS基因、毒力基因、耐药基因和分子分型, 96孔板结晶紫染色法检测生物膜形成能力。 结果 共纳入160株CRKP。标本来源以痰(46.9%)和血(26.3%)为主。CRKP菌株呈现多重耐药表型, 以携带bla_KPC(80.6%)为主, 其次为bla_NDM(17.5%)。根据是否携带T6SS将CRKP分为T6SS阳性组(129株, 80.6%)和T6SS阴性组(31株, 19.4%)。T6SS阳性组患者患慢性肺部疾病和心脏疾病比例高于T6SS阴性组(P < 0.05), 且预后较阴性组差(P < 0.05)。T6SS阳性组中, iucA、mrkD、rmpA2、peg344、wabG、fimH检出率均高于T6SS阴性组(均P < 0.05)。CRKP中以ST11型(68.8%)为主, 其中K64-ST11型占比70.9%, K47-ST11型占比25.5%。T6SS阳性组ST11型和K64-ST11型CRKP占比均高于T6SS阴性组(均P < 0.05)。T6SS阳性组CRKP生物膜形成能力强于T6SS阴性组(P < 0.001)。两组除bla_OXA-48基因外, 在携带其他碳青霉烯类耐药基因和抗菌药物耐药率方面差异无统计学意义。 结论 该地区CRKP呈现多重耐药, CRKP菌株T6SS检出率高, T6SS阳性CRKP毒力基因检出率更高, 且生物膜形成能力更强。     

抑制剂增强碳青霉烯类灭活法对革兰阴性杆菌碳青霉烯酶初步分类的评价

目的评价抑制剂增强碳青霉烯类灭活法(ieCIM)对革兰阴性杆菌碳青霉烯酶检测及初步分类的可靠性。方法分别以他唑巴坦和乙二胺四乙酸作为碳青霉烯酶抑制剂,对CIM进行改良。选取临床分离的198株肠杆菌科细菌和35株非发酵菌,采用ieCIM检测碳青霉烯酶并进行初步分类,以PCR方法检测碳青霉烯酶基因作对比。结果 198株肠杆菌科细菌中碳青霉烯酶基因阳性101株,CIM检测阳性99株;碳青霉烯酶基因阴性97株,CIM检测均阴性。35株非发酵菌中碳青霉烯酶基因阳性25株,CIM检测阳性24株;碳青霉烯酶基因阴性10株,CIM检测均阴性。使用ieCIM初步分类碳青霉烯酶,87株产A类酶菌株中检出85株(97.7%),25株产B类酶菌株中检出22株(88.0%),12株产D类酶菌株和2株同时产A、B类酶菌株全部检出,ieCIM检测敏感性为96%,特异性100%。结论 ieCIM与基因检测结果一致性高,适合临床微生物常规工作中对碳青霉烯酶的检测及初步分类。     

血培养中碳青霉烯类耐药鲍曼不动杆菌感染特征及耐药基因分析

目的 分析我院2018—2020年临床血培养检出的碳青霉烯类耐药鲍曼不动杆菌(carbapenem-resistant Acinetobacter Baumannii, CRAB)的感染特征及耐药基因分布情况,为防止院内感染、临床抗菌药物的合理使用及临床早期经验性提供依据。方法 收集2018年1月至2020年12月临床分离的血培养鲍曼不动杆菌48株,应用Logistic回归分析血流感染CRAB的可能危险因素。采用VITEK2 Compact全自动微生物分析系统进行细菌鉴定及药敏试验,热裂解法提取DNA,并应用PCR的方法检测常见鲍曼不动杆菌的碳青霉烯类耐药基因(OXA-23、OXA-51、NDM-1)及插入序列ISAba-1、整合酶Int I基因。结果 在所有XDR-AB中重症医学科的检出率最高,占68.4%。Logistic回归分析结果显示,肺炎、恶性肿瘤、静脉穿刺置管、输血、气管插管、尿管插管、胃管插管及支气管镜检查与血流感染CRAB有关(P<0.05),且肺炎(OR=81.894)是血流感染CRAB的独立危险因素(χ²=4.689,P<0.05)。多重耐药菌(13株)和广泛耐药菌(19株)均携带有OXA-23与OXA-51基因。敏感菌株中OXA-51基因检出率为43.8%,没有检测出OXA-23基因。48株菌株均没有检测出NDM-1基因。耐药基因OXA-23、OXA-51、ISAba-1的检出率在耐药菌和敏感菌之间差异有统计学意义(χOXA-232=48.000,χOXA-512=13.066,χISAba-12=15.709,均P<0.05)。结论 肺炎为我院血流感染CRAB的独立危险因素,非恶性肿瘤的患者感染CRAB的风险是有恶性肿瘤患者的21倍。本院碳青霉烯类耐药鲍曼不动杆菌主要为OXA-23型与OXA-51型菌株,且携带有OXA-23耐药基因的鲍曼不动杆菌对碳青霉烯类药物耐药率为100%,未携带该耐药基因的鲍曼不动杆菌对该类药物均呈敏感,提示OXA-23基因可能是造成CRAB耐药的原因,临床应加强院感管理,合理使用抗菌药物,防止该类鲍曼不动杆菌的暴发传播。     

Molecular and Epidemiological Characterization of Carbapenem-Resistant Acinetobacter baumannii in Non-Tertiary Korean Hospitals

Purpose

The increasing prevalence and global spread of carbapenem-resistant Acinetobacter baumannii (A. baumannii) has become a serious problem. The aim of this study was to investigate molecular and epidemiological characteristics of carbapenem-resistant A. baumannii isolates collected from Korean non-tertiary hospitals.

Materials and Methods

Thirty six non-duplicated carbapenem-resistant A. baumannii isolates were collected from 17 non-tertiary hospitals in Korea between 2004 and 2006. Isolates were typed by multilocus sequence typing and repetitive-sequence-based PCR (rep-PCR). Detection of genes encoding OXA carbapenemase and their relationship with ISAba1 was performed by PCR.

Results

Two clones were prevalent among 36 isolates: ST69 (17 isolates, 47.2%) and ST92 (19 isolates, 52.8%). Rep-PCR patterns were diverse and revealed that all isolates were clustered into eight band patterns. The ISAba1-activated blaOXA-23-like and ISAba1-activated blaOXA-51-like genes were prevalent among the carbapenem-resistant A. baumannii isolates.

Conclusion

The class D β-lactamase genes of A. baumannii were distributed nationwide in non-tertiary Korean hospitals.     

Bacteraemia due to OXA-48-carbapenemase-producing Enterobacteriaceae: a major clinical challenge

Bacteraemia due to carbapenemase-producing Enterobacteriaceae is an emerging medical problem. Management of this entity is complicated by the difficulty in Identifying resistance patterns and the limited therapeutic options. A cohort study was performed including all episodes of bloodstream infection due to OXA-48-producing Enterobacteriaceae (O48PE), occurring between July 2010 and April 2012. Data on predisposing factors, clinical presentation, therapy and outcome were collected from medical records. There were 40 cases of bacteraemia caused by O48PE, 35 Klebsiella pneumoniae and five Escherichia coli. Patients were elderly with significant comorbidities (57.5% underlying malignancy). Thirty-five cases (87.5%) were nosocomial, and five (12.5%) were healthcare-associated. Patients had frequently been exposed to antibiotics and to invasive procedures during hospitalization. The most common source of bacteraemia was the urinary tract followed by deep intra-abdominal surgical site infection. Clinical presentation was severe sepsis or shock in 18 cases (45%). Extended-spectrum β-lactamase production was detected in 92.5% of isolates. MIC₉₀ for ertapenem, imipenem and meropenem were 32, 16 and 16 mg/L, respectively. Most frequently preserved antibiotics were amikacin, colistin, tigecycline and fosfomycin. These antibiotics combined are the basis of targeted therapies, including carbapenem in selected cases. Median delay in starting clinically adequate and microbiologically appropriate treatment was 3 days. Crude mortality during admission and within 30 days from bacteraemia was 65% and 50%, respectively. Bloodstream infections caused by O48PE have a poor prognosis. Delay in diagnosis and in initiation of optimal antimicrobial therapy is frequent. Suspicion and rapid identification could contribute to improving outcomes.     

Evaluation of Disk carbapenemase test using improved disks for rapid detection and differentiation of clinical isolates of carbapenemase-producing Enterobacterales

ObjectivesRapid detection of carbapenemase-producing Enterobacterales (CPE) is important to control spread of the resistance. We previously reported that imipenem disks prepared from injectable imipenem-cilastatin could rapidly detect KPC- and NDM-type carbapenemases. In the present study, we evaluated performance of disks of IPM and combined disks of imipenem-tazobactam and imipenem-EDTA, which were prepared from powders of imipenem and inhibitors.MethodsIsolates of Enterobacterales were recovered from specimens of patients at a tertiary care hospital in Korea during January 2017 and March 2018. Routine CPE detection was performed by the CPE surveillance personnel whereas evaluation of the Disk carbapenemase test (DCT) was performed by the other personnel without knowing the results of surveillance. The DCT was carried out by pressing disks on to colonies and rehydrating in Petri plates and observing color change.ResultsThe DCT differentiated 688 of 694 (sensitivity 99.1%) carbapenemase-producing isolates in 2.5–20 min: 630 with KPC, 51 with NDM, three with IMP, one with VIM, two with KPC and IMP, and one with NDM and OXA-181. The DCT failed to detect six OXA- 48-like enzyme-producing isolates, but the modified method using 96-well flat-bottom microplates with mineral oil cover detected all 29 OXA-48-like enzyme-producing isolates in 20–120 min. The DCT was negative for all 440 ertapenem-nonsusceptible, carbapenemase gene-negative isolates (specificity 100%).ConclusionThe procedure of DCT is simple and can differentiate isolates of Enterobacterales with KPC-, NDM-, IMP- and VIM-type carbapenemases rapidly, and the modified DCT can detect isolates with OXA-48-like enzymes rapidly.