Carbapenem-resistant KPC-2-producing Escherichia coli in a Tel Aviv Medical Center, 2005 to 2008

Pseudomonas aeruginosa strains isolated from animal with high virulence genes content and highly sensitive to antimicrobials

OBJECTIVES

P. aeruginosa is one of the most metabolically versatile bacteria having the ability to survive in multiple environments through its accessory genome. An important hallmark of P. aeruginosa is the high level of antibiotic resistance, which often makes eradication difficult and sometimes impossible. Evolutionary forces have led to this bacterium to develop high antimicrobial resistance with a variety of elements contributing to both intrinsic and acquired resistance. The objectives were to genetically and phenotypically characterizer P. aeruginosa strains isolated from companion animals of different species.

METHODS

We characterized a collection of 39 P. aeruginosa strains isolated from infected animals. The genetic characterization was in relation to chromosomal profile by PFGE; content of virulence gene; presence of genomic islands (GIs); genes of the cytotoxins exported by T3SS: exoU, exoS, exoT and exoY; and type IV pili allele. The phenotypic characterization was based on patterns of susceptibility to different antimicrobials.

RESULTS

Each strain had a PFGE profile, a high virulence genes content, and a large accessory genome. However, most of the strains presented high sensitivity to almost all antimicrobials tested, showing no acquired resistance (no β-lactamases). The exception to this lack of resistance was seen with penicillin.

CONCLUSIONS

P. aeruginosa could be a naturally sensitive bacterium to standard antimicrobials but could rapidly develop intrinsic and acquired resistance when the bacterium is exposed to pressure exerted by antibiotics, as observed in hospital settings.

Whole-Genome Sequencing Investigation of a Large Nosocomial Outbreak Caused by ST131 H30Rx KPC-Producing Escherichia coli in Italy

KPC-producing Escherichia coli (KPC-Ec) remains uncommon, being mainly reported as the cause of sporadic episodes of infection rather than outbreak events. Here we retrospectively describe the dynamics of a large hospital outbreak sustained by KPC-Ec, involving 106 patients and 25 hospital wards, during a six-month period. Twenty-nine representative KPC-Ec isolates (8/29 from rectal swabs; 21/29 from other clinical specimens) have been investigated by Whole-Genome Sequencing (WGS). Outbreak isolates showed a multidrug-resistant profile and harbored several resistance determinants, including bla_CTX-M-27, aadA5, dfrA17, sulI, gyrA1AB and parC1aAB. Phylogenomic analysis identified the ST131 cluster 1 (23/29 isolates), H30Rx clade C, as responsible for the epidemic event. A further two KPC-Ec ST131 clusters were identified: cluster 2 (n = 2/29) and cluster 3 (n = 1/29). The remaining KPC-Ec resulted in ST978 (n = 2/29) and ST1193 (n = 1/29), and were bla_KPC-3 associated. The KPC-Ec ST131 cluster 1, originated in a previous KPC-Kp endemic context probably by plasmid transfer, and showed a clonal dissemination strategy. Transmission of the bla_KPC gene to the globally disseminated high-risk ST131 clone represents a serious cause of concern. Application of WGS in outbreak investigations could be useful to better understand the evolution of epidemic events in order to address infection control and contrast interventions, especially when high-risk epidemic clones are involved.

Understanding the Epidemiology of Multi-Drug Resistant Gram-Negative Bacilli in the Middle East Using a One Health Approach

In the last decade, extended-spectrum cephalosporin and carbapenem resistant Gram-negative bacilli (GNB) have been extensively reported in the literature as being disseminated in humans but also in animals and the environment. These resistant organisms often cause treatment challenges due to their wide spectrum of antibiotic resistance. With the emergence of colistin resistance in animals and its subsequent detection in humans, the situation has worsened. Several studies reported the transmission of resistant organisms from animals to humans. Studies from the middle east highlight the spread of resistant organisms in hospitals and to a lesser extent in livestock and the environment. In view of the recent socio-economical conflicts that these countries are facing in addition to the constant population mobilization; we attempt in this review to highlight the gaps of the prevalence of resistance, antibiotic consumption reports, infection control measures and other risk factors contributing in particular to the spread of resistance in these countries. In hospitals, carbapenemases producers appear to be dominant. In contrast, extended spectrum beta lactamases (ESBL) and colistin resistance are becoming a serious problem in animals. This is mainly due to the continuous use of colistin in veterinary medicine even though it is now abandoned in the human sphere. In the environment, despite the small number of reports, ESBL and carbapenemases producers were both detected. This highlights the importance of the latter as a bridge between humans and animals in the transmission chain. In this review, we note that in the majority of the Middle Eastern area, little is known about the level of antibiotic consumption especially in the community and animal farms. Furthermore, some countries are currently facing issues with immigrants, poverty and poor living conditions which has been imposed by the civil war crisis. This all greatly facilitates the dissemination of resistance in all environments. In the one health concept, this work re-emphasizes the need to have global intervention measures to avoid dissemination of antibiotic resistance in humans, animals and the environment in Middle Eastern countries.

Plasmid-Mediated Transmission of KPC-2 Carbapenemase in Enterobacteriaceae in Critically Ill Patients

Carbapenem-resistant Enterobacteriaceae (CRE) cause health care-associated infections worldwide, and they are of severe concern due to limited treatment options. We report an outbreak of KPC-2-producing CRE that was caused by horizontal transmission of a promiscuous plasmid across different genera of bacteria and hospitals in Germany. Eleven isolates (8 Citrobacter freundii, 2 Klebsiella oxytoca, and 1 Escherichia coli) were obtained from seven critically ill patients during the six months of the outbreak in 2016. One patient developed a CRE infection while the other six patients were CRE-colonized. Three patients died in the course of the hospital stay. Six of the seven patients carried the same C. freundii clone; one K. oxytoca clone was found in two patients, and one patient carried E. coli and C. freundii. Molecular analysis confirmed the presence of a conjugative, bla_KPC-2-carrying 70 kb-IncN plasmid in C. freundii and E. coli and an 80 kb-IncN plasmid in K. oxytoca. All transconjugants harbored either the 70 or 80 kb plasmid with bla_KPC-2, embedded within transposon variant Tn4401g. Whole genome sequencing and downstream bioinformatics analyses of all plasmid sequences showed an almost perfect match when compared to a bla_KPC-2-carrying plasmid of a large outbreak in another German hospital two years earlier. Differences in plasmid sizes and open reading frames point to the presence of inserted mobile genetic elements. There are few outbreak reports worldwide on the transmission of bla_KPC-2-carrying plasmids across different bacterial genera. Our data suggest a regional and supraregional spread of bla_KPC-2-carrying IncN-plasmids harboring the Tn4401g isoform in Germany.

Klebsiella pneumoniae: a major worldwide source and shuttle for antibiotic resistance

Klebsiella pneumoniae is an important multidrug-resistant (MDR) pathogen affecting humans and a major source for hospital infections associated with high morbidity and mortality due to limited treatment options. We summarize the wide resistome of this pathogen, which encompasses plentiful chromosomal and plasmid-encoded antibiotic resistance genes (ARGs). Under antibiotic selective pressure, K. pneumoniae continuously accumulates ARGs, by de novo mutations, and via acquisition of plasmids and transferable genetic elements, leading to extremely drug resistant (XDR) strains harboring a 'super resistome'. In the last two decades, numerous high-risk (HiR) MDR and XDR K. pneumoniae sequence types have emerged showing superior ability to cause multicontinent outbreaks, and continuous global dissemination. The data highlight the complex evolution of MDR and XDR K. pneumoniae, involving transfer and spread of ARGs, and epidemic plasmids in highly disseminating successful clones. With the worldwide catastrophe of antibiotic resistance and the urgent need to identify the main pathogens that pose a threat on the future of infectious diseases, further studies are warranted to determine the epidemic traits and plasmid acquisition in K. pneumoniae. There is a need for future genomic and translational studies to decipher specific targets in HiR clones to design targeted prevention and treatment.

Meropenem Utilization Evaluation in a Referral Teaching Hospital in Iran

Objective:

Inappropriate use of antibiotics is associated with detrimental effects including emergence of antibiotic resistance. This study aimed to evaluate the use of meropenem, an extended-spectrum antibiotic, in a referral teaching hospital to detect different types of errors in its prescription.

Methods:

In a cross-sectional study performed over a 6-month period (2014–2015), hospitalized adult patients who received meropenem for any indication were randomly selected. The collected data included the indication for prescription and its correctness, the basis of prescription (empirical or culture based), administered dose, duration of treatment, the status of demanding sample culture in the case of empirical prescription, the status of dose adjustment in the case of renal impairment, and the treatment outcome.

Findings:

Over the study period, 123 patients were evaluated. The most frequent indication for prescription of meropenem was pneumonia (31.7%) and soft-tissue infections (18.7%). Out of these prescriptions, 62.6% (77 prescriptions) were incorrect. All meropenem prescriptions were initially empirical. Furthermore, sample culture and antibiotic susceptibility test were requested for only 52% of patients (n = 66). Treatment duration was correct for 53.7% of patients. Seventeen patients (13.8%) received an inappropriate dose of the antibiotic. Furthermore, of 51 patients who needed meropenem dose adjustment because of renal impairment, 17 patients (33.33%) received unadjusted dose.

Conclusion:

High rate of errors exists in the utilization of meropenem in our hospital, especially in the rank order of selection for treatment (indication), dose adjustment, and treatment duration. Therefore, modification strategies are necessary to promote the rational use of meropenem in this center.

Emergence of Escherichia coli Sequence Type 131 (ST131) and ST3948 with KPC-2, KPC-3 and KPC-8 carbapenemases from a Long-Term Care and Rehabilitation Facility (LTCRF) in Northern Italy

Aim of the study was to characterize KPC-producing Escherichia coli (KPC-Ec) clinical isolates among a Northern Italy Long-Term Care and Rehabilitation Facility (LTCRF) residents. Thirteen consecutive non repeated MDR E. coli isolates showing ertapenem Minimum Inhibitory Concentrations (MICs) >0.5 mg/L, collected during the period March 2011 - May 2013 from ASP "Redaelli" inpatients, were investigated. The bla KPC/CTX-M/SHV/TEM/OXA genes were identified by PCR and sequencing. KPC-Ec isolates underwent phylotyping, Pulsed-Field Gel Electrophoresis (PFGE), multilocus sequence typing (MLST) and repetitive sequence-based PCR (rep-PCR) profiling. Incompatibility groups analysis and conjugation were also performed. Eleven out of 13 isolates, resulted bla KPC-type positive, were consistently resistant to third generation cephalosporins, fluoroquinolones and trimethoprim-sulphametoxazole (84.6 %), retaining susceptibility to colistin (EUCAST guidelines). At least n = 4/11 of KPC-Ec patients received ≥48 h of meropenem therapy. Sequencing identified 9 bla KPC-2, 1 bla KPC-3 and 1 bla KPC-8 determinants. KPC-Ec plasmids belonged to IncF group (FIIk replicon); conjugation confirmed bla KPC/TEM-1/OXA-9 genes transferability for 10 KPC-Ec. Although three pulsotypes (A, B, C) were identified, all KPC-Ec belonged to phylogenetic group B2. Clone B (B-B5) caused an outbreak of infection involving nine inpatients at five wards. Rep-PCR showed relatedness for seven representative KPC-Ec isolates. Here we report a LTCRF outbreak caused by a ST131-B2 E. coli associated with bla KPC-2 and bla KPC-8 genes, and the emergence of the new ST3948. Elderly people with co-morbidities are at risk for ST131 colonization. KPC-Ec clones local monitoring appears essential both to avoid their spreading among healthcare settings, and to improve therapeutic choices for LTCRF residents.

Investigation of carbapenem resistance and the first identification of Klebsiella pneumoniae carbapenemase (KPC) enzyme among Escherichia coli isolates in Turkey: A prospective study

BACKGROUND

The aim of this study was to determine the presence of carbapenem resistance and carbapenemase production in Escherichia coli isolates from clinical samples in Turkey.

METHODS

The prospective study included a total of 4.052 Escherichia coli isolates collected from patients admitted to a hospital from March 2011 to May 2012. We used ertapenem disc for screening carbapenemase production, and the confirmation was performed by using Etest. The resistance mechanisms and genetic relatedness of the carbapenem resistant strains were investigated by using PCR (polymerase chain reaction) and pulsed-field gel electrophoresis (PFGE), respectively.

RESULTS

Among the 4.052 E. coli isolates, 24 (0.59%) were found to be carbapenem resistant. Of these, only 5 isolates were positive for OXA-48 and 2 isolates were positive for Klebsiella pneumoniae carbapenemase (KPC)-2. The KPC-2 producing E. coli strains (n = 2) were both isolated from the same patient. The bla_KPC genes were confirmed using DNA sequence analysis. The genetic relationship between the 24 E. coli strains studied by PFGE revealed that the strains were genetically unrelated.

CONCLUSIONS

This article confirms, to our knowledge for the first time, the detection of KPC-2-producing E. coli in Turkey, with OXA-48 being the most frequent carbapenemase in the study.

Pharmacokinetic and Pharmacodynamic Evaluation of Doripenem in Critically Ill Trauma Patients with Sepsis

BACKGROUND

Doripenem is approved by the Food and Drug Administration for the treatment of patients with complicated intra-abdominal infections and complicated urinary tract infections. While studies have described the pharmacokinetics/pharmacodynamics (PK/PD) of doripenem in the critically ill, no study has described the probability of target attainment profile among trauma patients with sepsis.

PATIENTS AND METHODS

This study was a prospective, open-label, pharmacokinetic study in the surgical intensive care unit (SICU) at Grady Health System. Thirty trauma patients with sepsis admitted to the SICU received doripenem 1 g infused over 4 hours every 8 hours for three doses. Blood samples were taken just before and after the third dose. A two-compartment model was fit to the data using non-parametric population PK modeling software. Embedded with the final PK model, a Monte Carlo Simulations (MCS) was performed to determine the PK/PD profile of doripenem 1 g, infused over 4 hours, every 8 hours after administration of the first and fourth doses.

RESULTS

Overall, the model fit the data well, and mean (standard deviation) clearance and volume of the central compartment were 16.9 (11.4) L/h and 28.5 (16.0) L, respectively. In the MCS analyses, doripenem 1 g, infused over 4 hours, administered every 8 hours, conferred >90% probabilities of achieving 30-50% time greater than the minimum inhibitory concentration (30-50% T>MIC) for MICs ≤2 mg/L after infusion of both the first and fourth doses. The MCS indicated that more intensive doripenem dosing schemes should be considered for organisms with MIC values in excess of 2 mg/L.

CONCLUSIONS

This is the first study to describe the doripenem PK/PD in critically ill patients with trauma. Among these patients, the MCS analyses suggest that current dosing strategies may be ineffective when the MIC value for the infecting pathogen is expected to be above 2 mg/L.

KPC-Like Carbapenemase-Producing Enterobacteriaceae Colonizing Patients in Europe and Israel

In a 2008-2011 survey, 17,945 patients in 18 hospital units in Europe and Israel were screened for carriage of Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae, resulting in identification of 124 positive patients. The isolates were dominated by Klebsiella pneumoniae sequence type 258 (ST258) KPC-2 and ST512 KPC-3, mainly from Greece and Italy, respectively, whereas Israeli isolates were of diverse species, clones, and KPC variants. Various blaKPC platforms were observed, among which IncFIIK-FIBK plasmids with blaKPC-2/-3 genes in the Tn4401a transposon prevailed.

Outbreak of KPC-3 Producing Carbapenem-Resistant Klebsiella pneumoniae in a US Pediatric Hospital

BACKGROUND

The increase in carbapenem-resistant Enterobacteriaceae (CRE) infections is a critical public health issue. We recently experienced the largest single-center pediatric outbreak of carbapenem-resistant Klebsiella pneumoniae (CRKP) at our hospital. The objective of this study was to describe the molecular epidemiology of this outbreak before and after infection-prevention interventions.

METHODS

All positive cultures and associated clinical conditions were reviewed to determine whether health care-associated infections (HAIs) exist. HAIs were defined using Centers for Disease Control and Prevention guidelines. CRKP isolates were collected and screened for the presence of β-lactamase genes. Strain relatedness of CRKP isolates was determined by field-inversion gel electrophoresis (FIGE) and multilocus sequence typing (MLST). Polymerase chain reaction (PCR) amplification and sequencing of blaTEM, blaSHV, and blaKPC genes were performed on representative isolates.

RESULTS

During March-July 2010, 18 CRKP isolates were recovered from 15 unique patients. Six isolates were considered HAIs; all were central-line-associated bloodstream infections. All isolates testing positive by PCR for blaKPC were found to carry KPC-3 in transposon Tn4401 isotype "b." FIGE revealed 2 prevalent patterns (accounting for 10 and 3 CRKP isolates, respectively) that MLST demonstrated to consist entirely of strains from ST730; the remaining FIGE types corresponded to ST14, ST15, and ST1559 (a single-locus variant of ST730), with these alternate backgrounds appearing later in the outbreak. New CRKP cases decreased after the implementation of infection-control interventions. All isolates were ciprofloxacin sensitive.

CONCLUSIONS

Molecular analyses document the introduction of a KPC-3-producing CRKP clone into our hospital setting, though some isolates appear to have other mechanisms of carbapenem resistance. The transition to a polyclonal epidemiology suggests that the initial outbreak was due to nosocomial spread of a single ST730 clone, while latter isolates may have been secondary to the introduction of a blaKPC-3/Tn4401 isotype "b"-containing plasmid into other K pneumoniae strain backgrounds versus new carbapenemase-producing bacteria.

Predictors of Rectal Carriage of Carbapenem-Resistant Enterobacteriaceae (CRE) among Patients with Known CRE Carriage at Their Next Hospital Encounter

Background.

Carbapenem-resistant Enterobacteriaceae (CRE) are important extremely drug-resistant pathogens that have emerged during the past decade. Early identification and isolation of carriers are key components of an effective infection control strategy in healthcare facilities. Very little is known about the natural history of CRE carriage. We aimed to determine the predictors of a positive CRE rectal screen test among patients with known CRE carriage screened at their next hospital encounter.

Methods.

A case-control study was conducted. Sixty-six patients who tested positive for CRE carriage were surveyed for CRE rectal carriage at the next hospital encounter; screen-positive patients were compared with screen-negative control patients. Data were extracted from the patients' medical records and from the hospital computerized database.

Results.

Twenty-three case patients and 43 control patients were identified. Predictors for a positive CRE rectal carriage test were (1) prior fluoroquinolone use (odds ratio [OR], 4.27; 95% confidence interval [CI], 1.10–16.6), (2) admission from an institution or another hospital (OR, 4.04; 95% CI, 1.33–12.37), and (3) time interval less than or equal to 3 months since the first positive CRE test (OR, 3.59; 95% CI, 1.24–10.37). Among patients with no predictor variables, the likelihood of having a positive screen test at the next hospital encounter was 1/7. If they had at least 1 predictor, the likelihood increased to 1/2.

Conclusions.

Prior fluoroquinolone use, transfer from another healthcare facility, and admission less than or equal to 3 months since the first CRE isolation are predictors of persistent CRE rectal carriage. These predictors can be used in designing CRE prevention strategies.

A multicenter study of the clonal structure and resistance mechanism of KPC-producing Escherichia coli isolates in Israel

Little is known about the molecular epidemiology of Klebsiella pneumoniae carbapenemase-producing Escherichia coli (KPCEC). We aimed to describe the clonal structure and resistance mechanisms of KPCEC in a multicenter study. The study included 88 isolates from four medical centres in Israel: Tel Aviv Medical Center (n = 17), Laniado Medical Center (n = 12), Sha'are-Zedek Medical Center (n = 38), and Rambam Medical Center (n = 21). Twelve (14%) KPCEC were from clinical sites and 86% from surveillance cultures. The clonal structure was studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and was highly diverse, with 79 and 45 different PFGE types and STs, respectively. The most common clones were ST-131 and ST-410, identified in 21 isolates (23%). Dominant clonal complexes (CCs) were CC131 (n = 16), CC410 (n = 14), CC10 (n = 17), and CC-69 (n = 6). The blaKPC-2 and blaKPC-3 genes were identified in 68 and 20 isolates, respectively. All isolates were non-susceptible to ertapenem; 16 (18%) and 35 (40%) isolates were susceptible (minimal inhibitory concentration ≤1 mg/L) to imipenem and meropenem, respectively. Isolates were susceptible to colistin, amikacin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole in 100%, 87%, 28%, 27%, and 21% of the cases, respectively. blaKPC-Harbouring plasmids from Tel Aviv Medical Center as well as from six CC-131 isolates from the other centres were studied by Inc and pMLST typing. Sixteen of the 20 blaKPC2-harbouring plasmids were of identical type, IncN-pMLST ST-15. In conclusion, the clonal structure of KPCEC in Israel is characterized by the predominance of known international extended-spectrum β-lactamase-producing clones and by high intra- and inter-institutional diversity. This suggests that in Israel, clonal spread does not play a major role in the dissemination of KPCEC.

Carbapenem-resistant Enterobacteriaceae: biology, epidemiology, and management

Introduced in the 1980s, carbapenem antibiotics have served as the last line of defense against multidrug-resistant Gram-negative organisms. Over the last decade, carbapenem-resistant Enterobacteriaceae (CRE) have emerged as a significant public health threat. This review summarizes the molecular genetics, natural history, and epidemiology of CRE and discusses approaches to prevention and treatment.

Complete sequence of a conjugative incn plasmid harboring blaKPC-2, blaSHV-12, and qnrS1 from an Escherichia coli sequence type 648 strain

We sequenced a novel conjugative blaKPC-2-harboring IncN plasmid, pYD626E, from an Escherichia coli sequence type 648 strain previously identified in Pittsburgh, Pennsylvania. pYD626E was 72,800 bp long and carried four β-lactamase genes, blaKPC-2, blaSHV-12, blaLAP-1, and blaTEM-1. In addition, it harbored qnrS1 (fluoroquinolone resistance) and dfrA14 (trimethoprim resistance). The plasmid profile and clinical history supported the in vivo transfer of this plasmid between Klebsiella pneumoniae and Escherichia coli.

Molecular epidemiology of KPC-producing Escherichia coli: occurrence of ST131-fimH30 subclone harboring pKpQIL-like IncFIIk plasmid

Of 20 Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli isolates identified at hospitals in western Pennsylvania, 60% belonged to the epidemic ST131-fimH30 subclone. IncFIIk was the most common replicon type for the blaKPC-carrying plasmids (n = 8). All IncFIIk plasmids possessed a scaffold similar to that of pKpQIL, and seven of them were borne by ST131-fimH30 isolates. IncN plasmids conferred resistance to trimethoprim-sulfamethoxazole, and IncA/C plasmids conferred resistance to gentamicin. Three blaKPC-carrying plasmids (IncA/C and IncN) possessed blaSHV-7/12 and qnrA1 or qnrS1.

Mix and match of KPC-2 encoding plasmids in Enterobacteriaceae-comparative genomics

We performed comparative sequence analysis of 3 blaKPC-2 encoding plasmids to examine evolution of these plasmids and their dissemination. We found that all of them have an IncN replicon with a newly determined IncN plasmid sequence type (ST), ST15. The 2 Klebsiella pneumoniae (KPN) plasmids also harbor an IncF2A1-B1- replicon. The blaKPC-2 is located in the Tn4401c transposon with a newly discovered mutation in the P2 promoter. Screening of the 27 additional blaKPC-2 carrying plasmids from Enterobacter cloacae, Escherichia coli (EC), and K. pneumoniae showed that: all KPN and EC plasmids are IncN plasmids belonging to ST15; 4/7 KPN and 1/6 EC plasmids contain an additional IncF2A1-B1- replicon; all Enterobacter plasmids belong to neither IncN nor IncF2A1-B1- replicon plasmids; 6/7 KPN and 2/5 EC plasmids carry the mutated P2 promoter. Study of the blaKPC-2 environment, transposon, pMLST, and Inc group suggests transposon and plasmid inter- and intra-species dissemination and evolution.

Updated molecular epidemiology of carbapenem-non-susceptible Escherichia coli in Taiwan: first identification of KPC-2 or NDM-1-producing E. coli in Taiwan

BACKGROUND

The global spread and increasing incidence of carbapenem-resistant Enterobacteriaceae have resulted in treatment and public health concerns. Here, we present an investigation of the molecular mechanisms and clonality of carbapenem-non-susceptible Escherichia coli (CnSEC) based on a nationwide survey in Taiwan.

METHODS

We collected 32 and 43 carbapenem-non-susceptible E. coli isolates in 2010 and 2012, respectively. The genes encoding cabapenemases and plasmidic AmpC-type and extended-spectrum β-lactamases (EBSLs) were analyzed by polymerase chain reaction (PCR). The major porin channels OmpF and OmpC were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Molecular typing was performed with pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST).

RESULTS

The resistance rates of CnSEC isolates to cefazolin, cefotaxime, cefoxitin, ceftazidime, and ertapenem were all 100%, and most (94.7%) isolates were CMY producers. The main mechanism of CnSEC in Taiwan is via plasmidic AmpC β-lactamase CMY-2 and DHA-1 in combination with the loss of OmpC/F. In 2010, one isolate was confirmed to harbor blaIMP-8; a KPC-2 producer and an NDM-1 producer were detected in 2012. No isolate had VIM- or OXA-carbapenemases. ST131 was the predominant ST type (33.3%). PFGE revealed no large cluster in CnSEC isolates in Taiwan.

CONCLUSIONS

The co-existence of plasmidic AmpC β-lactamase and outer membrane protein loss is the main mechanism for CnSEC in Taiwan. The emergence of KPC-2 and NDM-1 in 2012 and the predominance of ST131 warrant close monitoring and infection control.

Emergence of Escherichia coli sequence type 131 isolates producing KPC-2 carbapenemase in China

Twenty-two KPC-2-producing Escherichia coli isolates were obtained from three hospitals in Hangzhou, China, from 2007 to 2011. One isolate, with OmpC porin deficiency, exhibited high-level carbapenem resistance. Pulsed-field gel electrophoresis showed that few isolates were indistinguishable or closely related. Multilocus sequence typing indicated that sequence type 131 (ST131) was the predominant type (9 isolates, 40.9%), followed by ST648 (5 isolates), ST405 (2 isolates), ST38 (2 isolates), and 4 single STs, ST69, ST2003, ST2179, and ST744. Phylogenetic analysis indicated that 9 group B2 isolates belonged to ST131, and 5 of 11 group D isolates belonged to ST648. Only one group B1 isolate and one group A isolate were identified. A representative plasmid (pE1) was partially sequenced, and a 7,788-bp DNA fragment encoding Tn3 transposase, Tn3 resolvase, ISKpn8 transposase, KPC-2, and ISKpn6-like transposase was obtained. The blaKPC-2-surrounding sequence was amplified by a series of primers. The PCR results showed that 13 isolates were consistent with the genetic environment in pE1. It is the first report of rapid emergence of KPC-2-producing E. coli ST131 in China. The blaKPC-2 gene of most isolates was located on a similar genetic structure.

Correlations of antibiotic use and carbapenem resistance in enterobacteriaceae

Epidemiological studies have shown a link between carbapenem use and resistance; however, the clinical relationship between antibiotic consumption and the epidemiology of carbapenem-intermediate or -resistant Enterobacteriaceae (CIRE) remains unclear. This study sought to analyze temporal antibiotic consumption trends for relationships with incident CIRE. In total, 310,892 days of therapy and 55 deduplicated CIRE were analyzed. When conservative corrections were applied for multiple comparisons, carbapenem class use and piperacillin-tazobactam use retained significant positive and negative relationships with the incidence of CIRE, respectively.

Carbapenemases in Klebsiella pneumoniae and other Enterobacteriaceae: an evolving crisis of global dimensions

SUMMARY

The spread of Enterobacteriaceae, primarily Klebsiella pneumoniae, producing KPC, VIM, IMP, and NDM carbapenemases, is causing an unprecedented public health crisis. Carbapenemase-producing enterobacteria (CPE) infect mainly hospitalized patients but also have been spreading in long-term care facilities. Given their multidrug resistance, therapeutic options are limited and, as discussed here, should be reevaluated and optimized. Based on susceptibility data, colistin and tigecycline are commonly used to treat CPE infections. Nevertheless, a review of the literature revealed high failure rates in cases of monotherapy with these drugs, whilst monotherapy with either a carbapenem or an aminoglycoside appeared to be more effective. Combination therapies not including carbapenems were comparable to aminoglycoside and carbapenem monotherapies. Higher success rates have been achieved with carbapenem-containing combinations. Pharmacodynamic simulations and experimental infections indicate that modification of the current patterns of carbapenem use against CPE warrants further attention. Epidemiological data, though fragmentary in many countries, indicate CPE foci and transmission routes, to some extent, whilst also underlining the lack of international collaborative systems that could react promptly and effectively. Fortunately, there are sound studies showing successful containment of CPE by bundles of measures, among which the most important are active surveillance cultures, separation of carriers, and assignment of dedicated nursing staff.

Involvement of MarR and YedS in carbapenem resistance in a clinical isolate of Escherichia coli from China

A carbapenem-resistant clinical isolate of Escherichia coli, which lacked OmpF and OmpC porins, carried a marR mutation and expressed a functional yedS, a normally nontranslated gene. MarR and YedS are described here as having effects on the ability of this strain to resist carbapenems. Additionally, expression of YedS was regulated by the small RNA MicF in a MarA-dependent way. These findings illustrate how broadly bacteria can mutate within a selective clinical setting, in this case, resistance to carbapenems, by altering three porin genes and one regulatory gene.

Molecular characteristics of KPC-producing Enterobacteriaceae at the early stage of their dissemination in Poland, 2008-2009

After the first report in May 2008, the National Reference Center for Susceptibility Testing confirmed 113 cases of infection or colonization by KPC-producing members of the family Enterobacteriaceae in Poland by the end of 2009. The vast majority of patients were found in 18 hospitals; three patients were diagnosed at outpatient clinics. Most of the institutions were in the Warsaw area, including three hospitals with the highest numbers of cases. When available, the data on previous hospitalizations often indicated that these hospitals were the probable acquisition sites; one patient arrived from New York. The group of 119 unique isolates consisted of Klebsiella pneumoniae (n = 114), followed by Klebsiella oxytoca (n = 3), and Escherichia coli (n = 2). The K. pneumoniae isolates were dominated by the clone sequence type 258 (ST258) (n = 111); others were ST11 and ST23. The ST258 group was heterogeneous, with 28 pulsed-field gel electrophoresis (PFGE) subtypes, ∼25 plasmid profiles, and nine β-lactamase patterns differing by KPC variants (KPC-2 mainly), and SHV-12, CTX-M-3, and TEM-1-like enzymes. Plasmids carrying bla(KPC) genes varied in size (~48 to 250 kb), structure, and conjugation potential. Transferable IncFII(K) plasmids of ~110 to 160 kb, probably pKpQIL or its derivatives, were observed in all K. pneumoniae clones and in K. oxytoca. Also prevalent were nontypeable pETKp50-like plasmids of ~50 kb, found in K. pneumoniae ST258 and E. coli isolates (ST93 and ST224). Two K. pneumoniae-E. coli pairs from single patients might represent the in vivo transfer of such plasmids. The striking diversity of KPC producers at the early stage of dissemination could result from several introductions of these bacteria into the country, their multidirectional evolution during clonal spread, and transfer of the plasmids.

Clinical epidemiology of carbapenem-intermediate or -resistant Enterobacteriaceae

OBJECTIVES

Despite the increasing incidence of carbapenem-intermediate or -resistant Enterobacteriaceae (CIRE), risk factors associated with CIRE infections have not been well defined. This study characterizes factors associated with CIRE among two different source populations.

METHODS

A case-control study was performed at a tertiary care medical centre between January 2005 and December 2009. Cases were adults with a culture-confirmed Enterobacteriaceae infection with reduced susceptibility to meropenem or ertapenem. The CIRE cases were matched 1:1 to patients from two different control series: (i) those with carbapenem-susceptible Enterobacteriaceae (CSE) infections; and (ii) inpatients residing on the same ward within 30 days of CIRE culture date. Logistic regression was used to identify variables independently associated with CIRE among each source population. Restricted multivariate analyses were performed to determine if covariates predictive of CIRE varied by infecting organism or presence of the bla(KPC) gene.

RESULTS

There were 102 cases of CIRE during the study period. The only covariate independently associated with CIRE in all multivariate analyses was the cumulative number of prior antibiotic exposures. Compared with CSE controls, the odds ratios (95% confidence interval) were 1.43 (1.19-1.72), 2.05 (1.70-2.47) and 2.93 (2.43-3.53) for 1, 2 and ≥ 3 antibiotic exposures, respectively. The strength of this association was comparable for the hospitalized control group and analyses stratified by organism and presence of the bla(KPC) gene.

CONCLUSIONS

A patient's cumulative antibiotic exposure history is likely to be more important than any one specific exposure when determining the likelihood of developing a CIRE infection.

Laboratory and clinical evaluation of screening agar plates for detection of carbapenem-resistant Enterobacteriaceae from surveillance rectal swabs

The increased worldwide spread of carbapenem-resistant Enterobacteriaceae (CRE) emphasizes the need for a sensitive screening procedure to identify these microorganisms. Gastrointestinal carriers may serve as the reservoir for cross-transmission in the health care setting, and thus active surveillance is a key part in preventing the spread of such strains. Three agar-based methods for direct CRE detection from rectal swabs were compared: CHROMagar-KPC (Chrom); MacConkey agar with imipenem at 1 μg/ml (MacI); and MacConkey plates with imipenem, meropenem, and ertapenem disks (MacD). First, we compared the levels of detection (LODs) of 10 molecularly characterized carbapenemase-producing Enterobacteriaceae strains by the three methods. Second, we compared their performance in a surveillance study using rectal swabs (n = 139). The LODs of carbapenemase-producing Enterobacteriaceae strains were influenced by their MICs to carbapenems and were best for MacI, followed by Chrom. The MacD method was able to detect only the strains exhibiting MICs of ≥ 32 μg/ml to at least ertapenem. In the surveillance study, both Chrom and MacI had greater sensitivity (85%) than MacD (76%). However, MacI was the most specific method. In conclusion, MacI appears to be most appropriate medium for the detection of CRE in settings in which multiclonal CRE strains with various MICs to carbapenems are circulating.

Transfer of KPC-2 Carbapenemase from Klebsiella pneumoniae to Escherichia coli in a patient: first case in Europe

The first case in Europe of Klebsiella pneumoniae carbapenemase (KPC) 2 transfer from K. pneumoniae to Escherichia coli in the same patient is described. KPC-positive plasmids from the two species were identical, indicating horizontal plasmid transfer. Selection of the KPC-producing E. coli strain was triggered by therapy with meropenem.

Multiresistant Gram-negative bacteria: the role of high-risk clones in the dissemination of antibiotic resistance

Multilocus sequence typing reveals that many bacterial species have a clonal structure and that some clones are widespread. This underlying phylogeny was not revealed by pulsed-field gel electrophoresis, a method better suited to short-term outbreak investigation. Some global clones are multiresistant and it is easy to assume that these have disseminated from single foci. Such conclusions need caution, however, unless there is a clear epidemiological trail, as with KPC carbapenemase-positive Klebsiella pneumoniae ST258 from Greece to northwest Europe. Elsewhere, established clones may have repeatedly and independently acquired resistance. Thus, the global ST131 Escherichia coli clone most often has CTX-M-15 extended-spectrum β-lactamase (ESBL), but also occurs without ESBLs and as a host of many other ESBL types. We explore this interaction of clone and resistance for E. coli, K. pneumoniae, Acinetobacter baumannii- a species where three global lineages dominate--and Pseudomonas aeruginosa, which shows clonal diversity, but includes the relatively 'tight' serotype O12/Burst Group 4 cluster that has proved adept at acquiring resistances--from PSE-1 to VIM-1 β-lactamases--for over 20 years. In summary, 'high-risk clones' play a major role in the spread of resistance, with the risk lying in their tenacity--deriving from poorly understood survival traits--and a flexible ability to accumulate and switch resistance, rather than to constant resistance batteries.

Molecular epidemiology, sequence types, and plasmid analyses of KPC-producing Klebsiella pneumoniae strains in Israel

Sporadic isolates of carbapenem-resistant KPC-2-producing Klebsiella pneumoniae were isolated in Tel Aviv Medical Center during 2005 and 2006, parallel to the emergence of the KPC-3-producing K. pneumoniae sequence type 258 (ST 258). We aimed to study the molecular epidemiology of these isolates and to characterize their bla(KPC)-carrying plasmids and their origin. Ten isolates (8 KPC-2 and 2 KPC-3 producing) were studied. All isolates were extremely drug resistant. They possessed the bla(KPC) gene and varied in their additional beta-lactamase contents. The KPC-2-producing strains belonged to three different sequence types: ST 340 (n = 2), ST 277 (n = 2), and a novel sequence type, ST 376 (n = 4). Among KPC-3-producing strains, a single isolate (ST 327) different from ST 258 was identified, but both strains carried the same plasmid (pKpQIL). The KPC-2-encoding plasmids varied in size (45 to 95 kb) and differed among each of the STs. Two of the Klebsiella bla(KPC-2)-carrying plasmids were identical to plasmids from Escherichia coli, suggesting a common origin of these plasmids. These data indicate that KPC evolution in K. pneumoniae is related to rare events of interspecies spread of bla(KPC-2)-carrying plasmids from E. coli followed by limited clonal spread, whereas KPC-3 carriage in this species is related almost strictly to clonal expansion of ST 258 carrying pKpQIL.