Characterization of novel VIM carbapenemase,VIM-38, and first detection of GES-5 carbapenem-hydrolyzing β-lactamases in Pseudomonas aeruginosa in Turkey

Pseudomonas aeruginosa isolates were collected form a Turkish hospital. Antimicrobial susceptibility was performed using the Vitek 2 Compact system, and 24 isolates were categorized as multidrug resistant (n = 18), extensively-drug resistant (n = 5), or pan-drug resistant (n = 1). PCR and DNA sequence analysis revealed that 1 strain possessed the bla_GES-5 and another carried a novel bla_VIM variant, named VIM-38. This new gene exhibited 1 amino acid substitution (Ala265Val) in comparison to its closest variant, VIM-5. Both VIM encoding genes were clones and demonstrated similar susceptibility profile when expressed in identical background. The presence of VIM-38 increases the diversity of carbapenemases in Turkey.     

血流感染鲍氏复合体的特征分析

目的 分析引起血流感染鲍氏复合体的种类、分子分型及OXA型碳青霉烯酶的携带情况.方法 采用基因测序及脉冲场凝胶电泳(PFGE)方法对所有菌株进行鉴定分析,并统计药敏结果及相关感染指标,分析携带耐药基因情况.结果 经鉴定104株鲍氏复合体中有鲍氏不动杆菌89株,占85.5％,不动杆菌属基因型3群占5.8％,不动杆菌属基因型13TU群占2.9％,其他不动杆菌占5.8％;89株鲍氏不动杆菌PFGE聚类分型得到A型8株、B型13株、C型13株、D型11株、E型35株、其他型9株;89例患者接受手术治疗58例,占65.2％,静脉导管53例,占59.6％,腹腔引流管37例,占41.6％,死亡21例,占3.5％;89株鲍氏不动杆菌对亚胺培南、美罗培南的耐药率为82.5％、86.2％;89株鲍氏不动杆菌种有86株菌携带OXA- 51基因,74株菌携带OXA-23,未检测到OXA- 24和OXA- 58基因.结论 医院引起血流感染的鲍氏复合体主要为鲍氏不动杆菌,临床常规生化鉴定存在局限性;鲍氏不动杆菌菌株同源性较高,存在医院内交叉感染;创伤性手术和静脉插管是引起鲍氏不动杆菌感染的重要因素,临床应给予重视;鲍氏不动杆菌对碳青霉烯类耐药率较高,其耐药基因主要为OXA- 23、OXA- 51.     

碳青霉烯类非敏感肠杆菌科细菌的β-内酰胺酶检测及耐药性分析

目的：探讨碳青霉烯类非敏感肠杆菌科细菌产碳青霉烯酶、超广谱β-内酰胺酶（ESBLs）及对16种抗菌药物的耐药情况,为临床合理用药提供依据。方法收集2010年1月至2013年12月临床分离的对碳青霉烯类非敏感的肺炎克雷伯菌214株、大肠埃希菌111株,采用改良Hodge试验对碳青霉烯酶进行检测,表型确证试验检测ESBLs,K-B纸片扩散法检测药敏试验。结果214株肺炎克雷伯菌单产碳青霉烯酶的阳性率为57.9%,单产ESBLs为12.6%,同时产ESBLs和碳青霉烯酶为20.6%;111株大肠埃希菌单产碳青霉烯酶的阳性率为54.1%,单产ESBLs为5.4%,同时产ESBLs和碳青霉烯酶为23.4%。试验菌株对临床常用的抗菌药物耐药性严重,耐药率在13.5%-98.1%之间,对米诺环素和替加环素耐药率低。结论对碳青霉烯类非敏感的肺炎克雷伯菌和大肠埃希菌产碳青霉烯酶率高,治疗该类细菌引起的感染可根据病原菌药敏试验结果和患者病情合理选用替加环素或米诺环素,以达到有效控制感染目的。     

First Canadian outbreak of Enterobacteriaceae-expressing Klebsiella pneumoniae carbapenemase type 3

BACKGROUND:

Organisms expressing Klebsiella pneumoniae carbapenemase (KPC) are found in several regions worldwide but are rarely detected in Canada. The first outbreak of KPC-expressing strains of Enterobacteriaceae clinical isolates in a university-affiliated hospital intensive care unit (ICU) in Canada is described.

METHODS:

Enterobacteriaceae isolates that were flagged by the Vitek 2 (bioMérieux, France) system as possible carbapenemase producers were subjected to the modified Hodge test. Modified Hodge test-positive organisms were analyzed by pulsed-field gel electrophoresis, tested for KPC and other beta-lactamase genes by polymerase chain reaction analysis and underwent subsequent nucleic acid sequencing. Antimicrobial susceptibility profiles were determined by Vitek 2 and Etest (bioMérieux, France). A chart review was conducted to establish epidemiological links.

RESULTS:

During the study period, 10 unique Enterobacteriaceae isolates expressing KPC were detected from nine ICU patients. Five patients had infections (three pneumonias, one surgical site infection, one urinary tract infection). Isolates included Escherichia coli (5), Klebsiella oxytoca (2), Serratia marcescens (2) and Citrobacter freundii (1). Polymerase chain reaction analysis and sequencing confirmed the presence of KPC-3 in all isolates; four also carried TEM, two CTX-M and one CMY-2. The imipenem minimum inhibitory concentrations as determined by Etest ranged from 0.75 μg/mL to ≥32 μg/mL. Pulsed field gel electrophoresis clonal patterns and patient location in the ICU revealed presumptive horizontal transmission events.

CONCLUSIONS:

In the present study, Enterobacteriaceae isolates with KPC are emerging and can result in serious infections. The KPC gene can spread via plasmids to different genera of the Enterobacteriaceae family. The dissemination of KPC in Enterobacteriaceae and the consequences for treatment and infection control measures warrant a high degree of vigilance among clinicians and microbiologists.     

Presence and characterization of blaNDM-1-positive carbapenemase-producing Klebsiella pneumoniae from outpatients in Thailand

BackgroundPresently, community-associated carbapenemase-producing Enterobacterales (CPE) remains largely unknown and require public attention. This study aimed to investigate the presence of CPE from outpatients in Thailand.MethodsNon-duplicate stool (n = 886) and urine (n = 289) samples were collected from outpatients with diarrhea and urinary tract infection, respectively. Demographic data and characteristics of patients were collected. Isolation of CPE was performed by plating enrichment culture on agar supplemented with meropenem. Carbapenemase genes were screened by PCR and sequencing. CPE isolates were phenotypically and genotypically characterized.ResultsFifteen samples (1.3%, 14 stool and 1 urine) yielded bla_NDM-1-positive carbapenemase-producing Klebsiella pneumoniae (CPKP). Additional resistance to colistin and tigecycline was observed in 53.3% and 46.7% of isolates, respectively. Age >60 years was identified as a risk factor for patients with CPKP (P < 0.001, adjusted odds ratio = 11.500, 95% confidence interval = 3.223–41.034). Pulsed field gel electrophoresis revealed genetic diversity of CPKP isolates; however, clonal spread has been observed. ST70 (n = 4) was common, followed by ST147 (n = 3). bla_NDM-1 from all isolates were transferable and mainly resided on IncA/C plasmid (80%). All bla_NDM-1 plasmids remained stable in bacterial host for at least 10 days in antibiotic-free environments, regardless of replicon types.ConclusionThis study demonstrates that the prevalence of CPE among outpatients in Thailand remains low and the spread of bla_NDM-1-positive CPKP may be driven by IncA/C plasmid. Our results emphasize the need for a large-scale surveillance study to limit further spread of CPE in community.     

Multidrug-resistant Enterobacterales infections in abdominal solid organ transplantation

BackgroundTransplant recipients are highly susceptible to multidrug-resistant (MDR) related infections. The lack of early appropriate antimicrobial treatment may contribute to the high mortality due to MDR-related infections in transplant recipients especially in case of metallo-β-lactamases.ObjectivesIn this review, we present the current state of knowledge concerning multidrug-resistant Gram negative bacilli's risk management in the care of solid-organ transplant recipients and suggest control strategies.SourcesWe searched for studies treating MDR g-negative bacilli related infections in the renal and hepatic transplant patient population. We included randomized and observational studies.ContentSolid-organ transplant is the best therapeutic option for patients diagnosed with end-stage organ disease. While the incidence of opportunistic infections is decreasing due to better prevention, the burden of “classical” infections related to MDR bacteria especially related to Gram-negative bacteria is constantly increasing.Over the last two decades, various MDR pathogens have emerged as a relevant cause of infection in this specific population associated with significant mortality. Several factors related to the management of transplant donor candidates and recipients increase the risk of MDR infections in transplant recipients. The awareness of this high susceptibility of transplant recipients to MDR-related infections challenges the choice of empirical therapy, while its appropriateness can only be validated a posteriori. Indeed, the lack of early appropriate antimicrobial treatment may contribute to the high mortality due to MDR-related infections in transplant recipients especially in case of metallo-β-lactamases.ImplicationsMultidrug-resistant Gram-negative bacteria are associated with high morbidity and mortality in solid organ transplant recipients. It seems important to identify patients at risk of colonization/MDR bacteria to evaluate strategies to limit the risk of secondary infections and to minimize the inappropriate use of broad-spectrum antibiotics.     

Rapid detection of carbapenem resistance among gram-negative organisms directly from positive blood culture bottles

BackgroundCarbapenemase producing gram-negative bacteria (GNB) has become a huge problem in majority of tertiary care centers worldwide. They are associated with very high morbidity and mortality rates, especially when they cause invasive infections. Therefore, rapid detection of these organisms is very important for prompt and adequate antibiotic therapy as well as infection control. The aim of this study was rapid detection of carbapenemase genes and thereby likely carbapenem resistance, 24–48 hours in advance, directly from the positive-flagged blood culture bottles using CHROMagar and Xpert® Carba-R.MethodsAspirate from positively flagged blood culture bottles was subjected to differential centrifuge. All gram-negative bacilli on gram stain from the deposit were processed in Xpert® Carba-R and inoculated on CHROMagar. The presence of genes and growth on CHROMagar was compared with carbapenem resistance on VITEK-2 Compact.ResultsA total of 119 GNB isolates were processed. One or more of the carbapenemase genes were detected in 80 isolates. On comparison with VITEK-2 result, 92 samples showed concordance for carbapenem resistance 48 hours in advance. There was discordance in 21 isolates with 12 major errors and 09 minor errors. The sensitivity of direct Xpert® Carba-R test for rapid detection of carbapenem resistance, 48 hours in advance, was 81.42%. The sensitivity of direct CHROMagar test for accurate detection of carbapenem resistance, 24 hours in advance, was 92.06%.ConclusionThe ability to detect carbapenem resistance with very high accuracy, 48 hours in advance, helps in appropriate antibiotic therapy and implementation of effective infection control practices.