Outbreak of infection with a multiresistant Klebsiella pneumoniae strain associated with contaminated roll boards in operating rooms

Factors associated with neonatal sepsis among neonates admitted in Kibungo Referral Hospital, Rwanda

More than one million neonatal deaths occur every year worldwide, of which 99% take place in low-income countries. In Rwanda, nearly 71% of neonatal deaths are preventable and among these, 10% are due to neonatal sepsis. Nevertheless, limited information exists on neonatal sepsis and its associated factors in Rwanda. The objectives of the study were to find prevalence and factors associated with neonatal sepsis among neonates admitted in Kibungo Referral Hospital, Ngoma District, Rwanda. We used a retrospective cross-sectional study design reviewing a subset of neonatal, maternal and laboratory records from Kibungo Hospital in 2017. Data were reviewed and collected from March to May, 2018. Logistic regression and odds ratios were calculated to identify the factors associated with neonatal sepsis at 95% CI, p < 0.05. Of the 972 total neonates' medical records from 2017, we randomly selected 422 of which 12.8% (n = 54) had neonatal sepsis. When blood cultures were positive, 62% grew Klebsiella pneumoniae. Among neonates with sepsis, 38 (70%) recovered while 16 (30%) died. Neonatal sepsis was strongly associated with neonatal age less than or equal to three days (aOR: 2.769, 95% CI 1.312-5.843; p = 0.008); and gestational age less than 37 weeks (aOR: 4.149; CI 1.1878-9.167; p ≤ 0.001). Increased use of blood cultures including sensitivity testing, routine surface cultures of the neonatology and maternity wards facilities, and systematic ward cleaning are all important approaches to prevent and treat neonatal infections in additional to regular neonatal sepsis evaluations.

Environmental Surface Hygiene in the OR: Strategies for Reducing the Transmission of Health Care-Associated Infections

Health care-associated infections (HAIs) cost billions of dollars annually in the United States and cause patient morbidity and mortality. There is increasing evidence that environmental surfaces in the OR setting, including anesthesia work areas, can harbor pathogens that can lead to HAIs. Patient-care equipment used routinely in the OR, such as electrocardiograph wires, blood pressure cuffs, pulse oximetry probes, and monitor cables, can become contaminated with pathogens during surgical procedures; without proper cleaning and disinfection between procedures, these items pose a risk for pathogen transmission and subsequent patient infections. This article discusses the association between contaminated surfaces in the OR and the risk for HAIs. It is essential that perioperative nurses, environmental services personnel, anesthesia technicians, and anesthesia professionals properly disinfect environmental surfaces to prevent HAIs.

Core genome MLST and resistome analysis of Klebsiella pneumoniae using a clinically amenable workflow

Whole genome sequencing (WGS) is replacing traditional microbiological typing methods for investigation of outbreaks in clinical settings. Here, we used a clinical microbiology laboratory core genome multilocus sequence typing (cgMLST) workflow to analyze 40 isolates of K. pneumoniae which are part of the Antimicrobial Resistance Leadership Group (ARLG) isolate collection, alongside 10 Mayo Clinic K. pneumoniae isolates, comparing results to those of pulsed-field gel electrophoresis (PFGE). Additionally, we used the WGS data to predict phenotypic antimicrobial susceptibility (AST). Thirty-one of 40 ARLG K. pneumoniae isolates belonged to the same PFGE type, all of which, alongside 3 isolates of different PFGE types, formed a large cluster by cgMLST. PFGE and cgMLST were completely concordant for the 10 Mayo Clinic K. pneumoniae isolates. For AST prediction, the overall agreement between phenotypic AST and genotypic prediction was 95.6%.

An overview of automated room disinfection systems: When to use them and how to choose them

Conventional disinfection methods are limited by reliance on the operator to ensure appropriate selection, formulation, distribution, and contact time of the agent. Automated room disinfection (ARD) systems remove or reduce reliance on operators and so they have the potential to improve the efficacy of terminal disinfection. The most commonly used systems are hydrogen peroxide vapor (H₂O₂ vapor), aerosolized hydrogen peroxide (aHP), and ultraviolet (UV) light. These systems have important differences in their active agent, delivery mechanism, efficacy, process time, and ease of use. The choice of ARD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation, and cost considerations.

[Monoclonal spread of multi-drug resistant CTX-M-15-producing Klebsiella pneumoniae. Impact of measures to control the outbreak]

OBJECTIVE

To describe an outbreak of multi-drug resistant extended-spectrum β-lactamases-producing Klebsiella pneumoniae (MDR-ESBL-KPN) and the impact of measures for its control.

METHODS

We reviewed the patients´ clinical records with MDR-ESBL-KPN isolation during 2013-2016 with resistance to fluoroquinolones, aminoglycosides, fosfomycin, and nitrofurantoin; susceptible to imipenem, meropenem, colistin, and tigecycline and variable to ertapenem and cotrimoxazole (Vitek-2). The genetic relationship between 35 isolates was established by PFGE and MLST. Control measures were put in place in January 2016.

RESULTS

We detected 269 patients colonized and/or infected by KPN-ESBL-MDR with a common resistance phenotype; the strains studied carried the blaCTX-M-15 gene and formed a single cluster belonging to ST11. The outbreak was detected at the end of 2015, although it began in 2013 in an elderly center. The acquisition source of the strains was: 6% community-acquired, 37% hospital-acquired (76% in internal medicine) and 57% related to long health care facilities (78% of hospitalizations in the last year). Ninety-four percent of patients had at least one underlying disease, 90% received antibiotics previously and 49% had some invasive devices. After the introduction of control measures, the incidence of cases in the quarter was reduced from 29 to 15.

CONCLUSIONS

We detected a monoclonal outbreak of MDR-CTX-M-15-KPN in 2015, with predominance of health-care associated cases. The success in the rapid spread of the outbreak was due to the delay in its detection and to the fact that most of the patients had previously received antibiotics. The control measures reduced the number of isolates by 50%.

Quantitative study about the role of environmental conditions in the survival capability of multidrug-resistant bacteria

BACKGROUND

Healthcare-associated infections (HAIs) caused by multidrug-resistant bacteria (MDRB) are of global concern and hospital textiles can contribute to their transmission. MDRB are able to survive on textiles for more than enough time to spread in the environment. Some studies summarized the effect of environmental factors on the duration of bacterial survival, but it remained an open question how these factors influence the quantity of surviving bacteria in a period of a few days, which is relevant from the perspective of HAIs. Investigating this effect can contribute to better understand the spread of MDRB and the emergence of hospital outbreaks.

METHODS

We investigated quantitatively the survival capability of 15 vancomycin-resistant Enterococcus faecium (VRE), 15 methicillin-resistant Staphylococcus aureus (MRSA), 15 multidrug-resistant Acinetobacter baumannii (MACI) and 15 multidrug-resistant Klebsiella pneumoniae (MRKP) in five environmental conditions using the plate count method. We examined the role of nutrients, textile types, temperature and level of relative humidity on bacterial survival after 1-7days of incubation.

RESULTS

Each bacterial group showed higher survival capability on 100% cotton towel than on 100% cotton sheet (P<0.01). MRSAs and VREs showed higher (P<0.01), MACIs showed lower (P=0.02) CFU/swatch values on 100% polyester sheet than on cotton sheet. The survival capability of MRKPs and MRSAs was higher inoculated in nutrient broth than in saline solution (P<0.01). Each bacterial group showed lower survival capability (P<0.01) at body condition (T=35°C, Rh=83%) than at control (T=25°C, Rh=52%).

CONCLUSIONS

Towels proved to be excellent conditions for each bacteria to survive, however chemical composition of the textiles affected differently the survival of Gram-positive and Gram-negative bacteria. These findings could be useful in searching for the source of outbreaks. Organic contamination of the textiles can increase the survival of desiccation-sensitive bacteria, therefore nutrient-rich inoculating medium is recommended in survival studies.

Anesthesia in patients with infectious disease caused by multi-drug resistant bacteria

PURPOSE OF REVIEW

Up to 50% of specific bacterial strains in healthcare admission facilities are multi-drug resistant organisms (MDROs). Involvement of anesthesiologists in management of patients carrying/at risk of carrying MDROs may decrease transmission in the Operating Room (OR).

RECENT FINDINGS

Anesthesiologists, their work area and tools have all been implicated in MDRO outbreaks. Causes include contamination of external ventilation circuits and noncontribution of filters to prevention, inappropriate decontamination procedures for nondisposable equipment (e.g. laryngoscopes, bronchoscopes and stethoscopes) and the anesthesia workplace (e.g. external surfaces of cart and anesthesia machine, telephones and computer keyboards) during OR cleaning and lack of training in sterile drug management.

SUMMARY

Discussions regarding the management of potential MDRO carriers must include anesthesia providers to optimize infection control interventions as well as the anesthesia method, the location of surgery and recovery and the details of patient transport. Anesthesia staff must learn to identify patients at risk for MDRO infection. Antibiotic prophylaxis, although not evidence based, should adhere to known best practices. Adjuvant therapies (e.g. intranasal Mupirocin and bathing with antiseptics) should be considered. Addition of nonmanual OR cleaning methods such as ultraviolet irradiation or gaseous decontamination is encouraged. Anesthesiologists must undergo formal training in sterile drug preparation and administration.

When are pathogen genome sequences informative of transmission events?

Recent years have seen the development of numerous methodologies for reconstructing transmission trees in infectious disease outbreaks from densely sampled whole genome sequence data. However, a fundamental and as of yet poorly addressed limitation of such approaches is the requirement for genetic diversity to arise on epidemiological timescales. Specifically, the position of infected individuals in a transmission tree can only be resolved by genetic data if mutations have accumulated between the sampled pathogen genomes. To quantify and compare the useful genetic diversity expected from genetic data in different pathogen outbreaks, we introduce here the concept of ‘transmission divergence’, defined as the number of mutations separating whole genome sequences sampled from transmission pairs. Using parameter values obtained by literature review, we simulate outbreak scenarios alongside sequence evolution using two models described in the literature to describe transmission divergence of ten major outbreak-causing pathogens. We find that while mean values vary significantly between the pathogens considered, their transmission divergence is generally very low, with many outbreaks characterised by large numbers of genetically identical transmission pairs. We describe the impact of transmission divergence on our ability to reconstruct outbreaks using two outbreak reconstruction tools, the R packages outbreaker and phybreak, and demonstrate that, in agreement with previous observations, genetic sequence data of rapidly evolving pathogens such as RNA viruses can provide valuable information on individual transmission events. Conversely, sequence data of pathogens with lower mean transmission divergence, including Streptococcus pneumoniae, Shigella sonnei and Clostridium difficile, provide little to no information about individual transmission events. Our results highlight the informational limitations of genetic sequence data in certain outbreak scenarios, and demonstrate the need to expand the toolkit of outbreak reconstruction tools to integrate other types of epidemiological data.

The increasing availability of genetic sequence data has sparked an interest in using pathogen whole genome sequences to reconstruct the history of individual transmission events in an infectious disease outbreak. However, such methodologies rely on pathogen genomes mutating rapidly enough to discriminate between infected individuals, an assumption that remains to be investigated. To determine pathogen outbreaks for which genetic data is expected to be informative of transmission events, we introduce here the concept of ‘transmission divergence’, defined as the number of mutations separating pathogen genome sequences sampled from transmission pairs. We characterise transmission divergence of ten major outbreak causing pathogens using simulations and find significant variation between diseases, with viral outbreaks generally exhibiting higher transmission divergence than bacterial ones. We reconstruct these outbreaks using the R-packages outbreaker and phybreak and find that genetic sequence data, though useful for rapidly evolving pathogens, provides little to no information about outbreaks with low transmission divergence, such as Streptococcus pneumoniae and Shigella sonnei. Our results demonstrate the need to incorporate other sources of outbreak data, such as contact tracing data and spatial location data, into outbreak reconstruction tools.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp.

Surface contamination in operating rooms: a risk for transmission of pathogens?

BACKGROUND

The role of surface contamination in the transmission of nosocomial pathogens is recognized increasingly. For more than 100 years, the inanimate environment in operating rooms (e.g., walls, tables, floors, and equipment surfaces) has been considered a potential source of pathogens that may cause surgical site infections (SSIs). However, the role of contaminated surfaces in pathogen acquisition in this setting generally is considered negligible, as most SSIs are believed to originate from patients' or healthcare workers' flora.

METHODS

A search of relevant medical literature was performed using PubMed to identify studies that investigated surface contamination of operating rooms and its possible role in infection transmission.

RESULTS

Despite a limited number of studies evaluating the role of surface contamination in operating rooms, there is accumulating evidence that the inanimate environment of the operating room can become contaminated with pathogens despite standard environmental cleaning. These pathogens can then be transmitted to the hands of personnel and then to patients and may result in SSIs and infection outbreaks.

CONCLUSION

Contaminated surfaces can be responsible for the transmission of pathogens in the operating room setting. Further studies are necessary to quantify the role of contaminated surfaces in the transmission of pathogens and to inform the most effective environmental interventions. Given the serious consequences of SSIs, special attention should be given to the proper cleaning and disinfection of the inanimate environment in operating rooms in addition to the other established infection control measures to reduce the burden of SSIs.

The changing epidemiology of hospital outbreaks due to ESBL-producing Klebsiella pneumoniae: the CTX-M-15 type consolidation

ABSTRACT 

Klebsiella pneumoniae is responsible for a large number of hospital outbreaks. In the 1990s, there were clonal epidemics, affecting mostly intensive care patients, which carried SHV and TEM enzyme types. With the advent of CTX-M-15 enzymes in the 2000, plasmids encoding multiple extended-spectrum β-lactamase (ESBL) types were described and, frequently, nosocomial outbreaks reported polyclonal dissemination and involved multiple Enterobacteriaceae. Worryingly, the interface between community and hospital is becoming blurred, and there is increasing evidence for the presence of ESBL-producing K. pneumoniae in the community. Furthermore, carbapenem resistance is increasingly reported in ESBL-producing K. pneumoniae strains. Infection control measures and stewardship programs are vital weapons in controlling the pandemic evolution of multidrug-resistant K. pneumoniae.

Polyclonal spread and outbreaks with ESBL positive gentamicin resistant Klebsiella spp. in the region Kennemerland, The Netherlands

Objective

The objective of this study was to analyze the transmission dynamics of ESBL positive Klebsiella spp. with an additional resistance towards gentamicin (ESBL-G) in a Dutch region of 650,000 inhabitants in 2012.

Methods

All patient related ESBL-G isolates isolated in 2012 were genotyped using both Amplification Fragment Length Polymorphism (AFLP) and High-throughput MultiLocus Sequence Typing (HiMLST). HiMLST was used to analyze the presence of (unidentified) clusters of ESBL-G positive patients. Furthermore, all consecutive ESBL-G isolates within patients were studied in order to evaluate the intra-patient variation of antibiotic phenotypes.

Results

There were 38 ESBL-G isolates, which were classified into 18 different sequence types (STs) and into 21 different AFLP types. Within the STs, four clusters were detected from which two were unknown resulting in a transmission index of 0.27. An analysis of consecutive ESBL-G isolates (with similar STs) within patients showed that for 68.8% of the patients at least one isolate had a different consecutive antibiotic phenotype.

Conclusion

The transmission of ESBL-G in the region Kennemerland in 2012 was polyclonal with several outbreaks (with a high level of epidemiological linkage). Furthermore, clustering by antibiotic phenotype characterization seems to be an inadequate approach in this setting. The routine practice of molecular typing of collected ESBL-G isolates may help to detect transmission in an early stage, which opens the possibility of a rapid response.

A guide to no-touch automated room disinfection (NTD) systems

Conventional disinfection methods are limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. ‘No-touch’ automated room disinfection (NTD) systems remove or reduce reliance on operators and so they have the potential to improve the efficacy of terminal disinfection. The most commonly used systems are hydrogen peroxide vapour (H₂O₂ vapour), aerosolised hydrogen peroxide (aHP) and ultraviolet (UV) radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints.

Rise and dissemination of aminoglycoside resistance: the aac(6')-Ib paradigm

Enzymatic modification is a prevalent mechanism by which bacteria defeat the action of antibiotics. Aminoglycosides are often inactivated by aminoglycoside modifying enzymes encoded by genes present in the chromosome, plasmids, and other genetic elements. The AAC(6′)-Ib (aminoglycoside 6′-N-acetyltransferase type Ib) is an enzyme of clinical importance found in a wide variety of gram-negative pathogens. The AAC(6′)-Ib enzyme is of interest not only because of his ubiquity but also because of other characteristics, it presents significant microheterogeneity at the N-termini and the aac(6′)-Ib gene is often present in integrons, transposons, plasmids, genomic islands, and other genetic structures. Excluding the highly heterogeneous N-termini, there are 45 non-identical AAC(6′)-Ib related entries in the NCBI database, 32 of which have identical name in spite of not having identical amino acid sequence. While some variants conserved similar properties, others show dramatic differences in specificity, including the case of AAC(6′)-Ib-cr that mediates acetylation of ciprofloxacin representing a rare case where a resistance enzyme acquires the ability to utilize an antibiotic of a different class as substrate. Efforts to utilize antisense technologies to turn off expression of the gene or to identify enzymatic inhibitors to induce phenotypic conversion to susceptibility are under way.

The role of 'no-touch' automated room disinfection systems in infection prevention and control

BACKGROUND

Surface contamination in hospitals is involved in the transmission of pathogens in a proportion of healthcare-associated infections. Admission to a room previously occupied by a patient colonized or infected with certain nosocomial pathogens increases the risk of acquisition by subsequent occupants; thus, there is a need to improve terminal disinfection of these patient rooms. Conventional disinfection methods may be limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. These problems can be reduced by the use of 'no-touch' automated room disinfection (NTD) systems.

AIM

To summarize published data related to NTD systems.

METHODS

Pubmed searches for relevant articles.

FINDINGS

A number of NTD systems have emerged, which remove or reduce reliance on the operator to ensure distribution, contact time and process repeatability, and aim to improve the level of disinfection and thus mitigate the increased risk from the prior room occupant. Available NTD systems include hydrogen peroxide (H(2)O(2)) vapour systems, aerosolized hydrogen peroxide (aHP) and ultraviolet radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. Typically, there is a trade-off between time and effectiveness among NTD systems. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints.

CONCLUSION

NTD systems are gaining acceptance as a useful tool for infection prevention and control.

Environmental contamination with extended-spectrum β-lactamases: is there any difference between Escherichia coli and Klebsiella spp?

BACKGROUND

The hospital environment contributes to the spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) during outbreaks. We aimed to assess the rate of environmental contamination in rooms occupied by ESBL carriers or infected children and to identify risk factors associated with contamination.

METHODS

Five environmental surface samples were systematically performed in rooms occupied by ESBL-PE carrier or infected children.

RESULTS

Forty-six Escherichia coli and 48 Klebsiella infected/carrier patients were included in the study. Nineteen (4%) of the 470 environmental samples performed yielded ESBL-PE. Klebsiella spp was the most frequent species isolated (16, 89%), whereas E coli and Citrobacter freundii were reported twice and once, respectively. Ten of the 19 (52%) isolates were identical to the corresponding strains isolated from children. Multivariate analysis highlighted ESBL-producing Klebsiella carriage/infection as the only risk factor significantly associated with surface contamination (P = .024).

CONCLUSION

Our data suggest that hospital environmental contamination is more frequent in instances of fecal carriage or infection with ESBL-producing Klebsiella than ESBL-producing E coli. Reinforcing hygiene measures around ESBL-producing Klebsiella might be necessary to reduce the spread of ESBL-PE in hospital environments.

Novel screening assay for in vivo selection of Klebsiella pneumoniae genes promoting gastrointestinal colonisation

Background

Klebsiella pneumoniae is an important opportunistic pathogen causing pneumonia, sepsis and urinary tract infections. Colonisation of the gastrointestinal (GI) tract is a key step in the development of infections; yet the specific factors important for K. pneumoniae to colonize and reside in the GI tract of the host are largely unknown. To identify K. pneumoniae genes promoting GI colonisation, a novel genomic-library-based approach was employed.

Results

Screening of a K. pneumoniae C3091 genomic library, expressed in E. coli strain EPI100, in a mouse model of GI colonisation led to the positive selection of five clones containing genes promoting persistent colonisation of the mouse GI tract. These included genes encoding the global response regulator ArcA; GalET of the galactose operon; and a cluster of two putative membrane-associated proteins of unknown function. Both ArcA and GalET are known to be involved in metabolic pathways in Klebsiella but may have additional biological actions beneficial to the pathogen. In support of this, GalET was found to confer decreased bile salt sensitivity to EPI100.

Conclusions

The present work establishes the use of genomic-library-based in vivo screening assays as a valuable tool for identification and characterization of virulence factors in K. pneumoniae and other bacterial pathogens.

Heat resistance mediated by a new plasmid encoded Clp ATPase, ClpK, as a possible novel mechanism for nosocomial persistence of Klebsiella pneumoniae

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. We have characterized a K. pneumoniae strain responsible for a series of critical infections in an intensive care unit over a two-year period. The strain was found to be remarkably thermotolerant providing a conceivable explanation of its persistence in the hospital environment. This marked phenotype is mediated by a novel type of Clp ATPase, designated ClpK. The clpK gene is encoded by a conjugative plasmid and we find that the clpK gene alone renders an otherwise sensitive E. coli strain resistant to lethal heat shock. Furthermore, one third of a collection of nosocomial K. pneumoniae isolates carry clpK and exhibit a heat resistant phenotype. The discovery of ClpK as a plasmid encoded factor and its profound impact on thermal stress survival sheds new light on the biological relevance of Clp ATPases in acquired environmental fitness and highlights the challenges of mobile genetic elements in fighting nosocomial infections.

Investigation of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae outbreaks in Hungary between 2005 and 2008

Fourteen outbreaks in Hungary between 2005 and 2008 caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) were epidemiologically investigated and the isolated pathogens were characterized by molecular techniques. Ten of the fourteen outbreaks occurred in adult wards and four in neonatal units affecting a total number of 73 patients. The 54% [40] of the patients developed bloodstream infections and 21.9%-21.9% [16] pneumonia and surgical site infections, respectively. The overall rate of mortality proved high: 36.9% [27]. Outbreaks in adults affected more patients, had higher attack rates, were more prolonged in duration and had a 6.9-fold higher mortality rate than outbreaks observed in neonates. The outbreaks in neonates were caused by SHV-type ESBL-producing klebsiellae, while in the "adult outbreaks" exclusively CTX-M-type ESBL-KP strains were involved. While the outbreak strains isolated from neonatal units could be assigned to a variety of pulsotypes, the previously described K. pneumoniae epidemic clones, ST15 and ST147, could be identified among the pathogens causing outbreaks in adult units.

Klebsiella pneumoniae multiresistance plasmid pMET1: similarity with the Yersinia pestis plasmid pCRY and integrative conjugative elements

Background

Dissemination of antimicrobial resistance genes has become an important public health and biodefense threat. Plasmids are important contributors to the rapid acquisition of antibiotic resistance by pathogenic bacteria.

Principal Findings

The nucleotide sequence of the Klebsiella pneumoniae multiresistance plasmid pMET1 comprises 41,723 bp and includes Tn1331.2, a transposon that carries the bla_TEM-1 gene and a perfect duplication of a 3-kbp region including the aac(6′)-Ib, aadA1, and bla_OXA-9 genes. The replication region of pMET1 has been identified. Replication is independent of DNA polymerase I, and the replication region is highly related to that of the cryptic Yersinia pestis 91001 plasmid pCRY. The potential partition region has the general organization known as the parFG locus. The self-transmissible pMET1 plasmid includes a type IV secretion system consisting of proteins that make up the mating pair formation complex (Mpf) and the DNA transfer (Dtr) system. The Mpf is highly related to those in the plasmid pCRY, the mobilizable high-pathogenicity island from E. coli ECOR31 (HPI_ECOR31), which has been proposed to be an integrative conjugative element (ICE) progenitor of high-pathogenicity islands in other Enterobacteriaceae including Yersinia species, and ICE_Kp1, an ICE found in a K. pneumoniae strain causing primary liver abscess. The Dtr MobB and MobC proteins are highly related to those of pCRY, but the endonuclease is related to that of plasmid pK245 and has no significant homology with the protein of similar function in pCRY. The region upstream of mobB includes the putative oriT and shares 90% identity with the same region in the HPI_ECOR31.

Conclusions

The comparative analyses of pMET1 with pCRY, HPI_ECOR31, and ICE_Kp1 show a very active rate of genetic exchanges between Enterobacteriaceae including Yersinia species, which represents a high public health and biodefense threat due to transfer of multiple resistance genes to pathogenic Yersinia strains.