Colistin-Nonsusceptible Pseudomonas aeruginosa Sequence Type 654 with blaNDM-1 Arrives in North America

Genetic Diversity in Antimicrobial Resistance Determinants Among Pathogenic Pseudomonas aeruginosa in India

The drastic rise in antibiotic resistance has become a global challenge, including India, due to high morbidity. The delayed identification and lack of treatment are the major causes of death. However, there is a shortage of precise information on the specific resistance pattern and sequence types of Pseudomonas aeruginosa from India that can help in diagnostics and therapy. A total of 16 clinical isolates were collected from the western region of India, along with 181 P. aeruginosa genomes of India from public database were retrieved and thoroughly analysed for antibiotics resistance determinants for associated sequence types and O-serotypes using different bioinformatics tools. Of all collected isolates (n = 16), 9 were extensively drug-resistant (XDR), 6 were multidrug-resistant (MDR), and only 1 isolate was susceptible to selected antibiotics. ST357 (n = 23; 11.6%) was the most frequent, followed by ST308, and ST1203. In serotyping, O11 (n = 85; 43%) was most prevalent. A novel ST4937 was reported and submitted to PubMLST. blaNDM-1 carbapenemase was found in (n = 45; 22.8%) isolates, whereas class D blaOXA-488 was present in (n = 38; 19.2%) isolates, further, several variants were found for class C blaPDC genes, where blaPDC-3 and blaPDC-19a were found to be predominant. We discovered that the amounts of carbapenemases and extended spectrum beta-lactamases (ESBL) genes were lower in India. This can be a relief sometimes, but a rise in high-risk clones could lead to longer hospital stays and more deaths. Therefore, ongoing surveillance of these strains is essential for effective infection management and containment of their spread.

Laboratory detection of carbapenemases among Gram-negative organisms

SUMMARYThe carbapenems remain some of the most effective options available for treating patients with serious infections due to Gram-negative bacteria. Carbapenemases are enzymes that hydrolyze carbapenems and are the primary method driving carbapenem resistance globally. Detection of carbapenemases is required for patient management, the rapid implementation of infection prevention and control (IP&C) protocols, and for epidemiologic purposes. Therefore, clinical and public health microbiology laboratories must be able to detect and report carbapenemases among predominant Gram-negative organisms from both cultured isolates and direct from clinical specimens for treatment and surveillance purposes. There is not a "one size fits all" laboratory approach for the detection of bacteria with carbapenemases, and institutions need to determine what fits best with the goals of their antimicrobial stewardship and IP&C programs. Luckily, there are several options and approaches available for clinical laboratories to choose methods that best suits their individual needs. A laboratory approach to detect carbapenemases among bacterial isolates consists of two steps, namely a screening process (e.g., not susceptible to ertapenem, meropenem, and/or imipenem), followed by a confirmation test (i.e., phenotypic, genotypic or proteomic methods) for the presence of a carbapenemase. Direct from specimen testing for the most common carbapenemases generally involves detection via rapid, molecular approaches. The aim of this article is to provide brief overviews on Gram-negative bacteria carbapenem-resistant definitions, types of carbapenemases, global epidemiology, and then describe in detail the laboratory methods for the detection of carbapenemases among Gram-negative bacteria. We will specifically focus on the Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii complex.

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis - update from 2017 to 2023

Background

Antimicrobial resistance (AMR) is a critical global health concern. A previous systematic review showed that migrants in Europe are at increased risk of AMR. Since the COVID-19 pandemic there have been rapid changes in patterns of antibiotic use, AMR, and migration. We aimed to present an updated evidence synthesis on the current distribution of AMR among migrants in Europe.

Methods

We carried out a systematic review and meta-analysis in accordance with PRISMA guidelines (PROSPERO ID: CRD42022343263). We searched databases (MEDLINE, Embase, PubMed and Scopus) from 18 January 2017 until 18 January 2023 to identify primary data from observational studies reporting any laboratory-confirmed AMR among migrants in the European Economic Area (EEA) and European Union-15 (EU-15) countries using over 7 key search terms for migrants and over 70 terms for AMR and countries in Europe. Outcomes were infection with, or colonisation of AMR bacteria. Methodological quality was assessed using Joanna Briggs Institute Critical Appraisal Checklist for Observational Studies. We meta-analysed the pooled-prevalence of infection and/or colonisation of AMR organisms.

Findings

Among 630 articles, 21 observational studies met the inclusion criteria and were included in this review. The pooled prevalence for any detected AMR was 28.0% (95% CI 18.0%-41.0%, I 2  = 100%) compared to a 25.4% seen in the previous review; gram-negative bacteria 31.0% (95% CI 20.0%-44.0%, I 2  = 100%), and methicillin-resistant staphylococcus aureus 10.0% (95% CI 5.0%-16.0%, I 2  = 99%). Drug-resistant bacteria were more prevalent in community settings in large migrant populations (pooled prevalence: 41.0%, 95% CI 24.0%-60.0%, I 2  = 99%) than in hospitals (21.0%, 95% CI 12.0%-32.0%, I 2  = 99%). AMR estimates in 'other' migrants were 32.0%, (95% CI 12.0%-57.0%, I 2  = 100%) and 28.0% (95% CI 18.0%-38.0%, I 2 = 100%) in forced migrants. No firm evidence of AMR acquisition with arrival time or length of stay in the host country was found.

Interpretation

Studies investigating AMR in migrants are highly heterogenous. However, since the COVID-19 pandemic, migrants may be at higher risk of acquiring resistant bacteria, particularly gram-negative bacteria, within community settings such as refugee camps and detention centres in Europe. Our study highlights the importance of infrastructure and hygiene measures within these settings, to mitigate transmission of resistant pathogens. Policy-makers should screen for AMR in migrants prior to departure from countries of origin, where feasible, and upon arrival to a new country to ensure optimal health screening, infection control and effective treatment.

Funding

There was no funding source for this study.

Genomic Characterization of Carbapenemase-Producing Enterobacter hormaechei, Serratia marcescens, Citrobacter freundii, Providencia stuartii, and Morganella morganii Clinical Isolates from Bulgaria

Carbapenemase-producing Enterobacter spp. Serratia marcescens, Citrobacter freundii, Providencia spp., and Morganella morganii (CP-ESCPM) are increasingly identified as causative agents of nosocomial infections but are still not under systematic genomic surveillance. In this study, using a combination of whole-genome sequencing and conjugation experiments, we sought to elucidate the genomic characteristics and transferability of resistance genes in clinical CP-ESCPM isolates from Bulgaria. Among the 36 sequenced isolates, NDM-1 (12/36), VIM-4 (11/36), VIM-86 (8/36), and OXA-48 (7/36) carbapenemases were identified; two isolates carried both NDM-1 and VIM-86. The majority of carbapenemase genes were found on self-conjugative plasmids. IncL plasmids were responsible for the spread of OXA-48 among E. hormaechei, C. freundii, and S. marcescens. IncM2 plasmids were generally associated with the spread of NDM-1 in C. freundii and S. marcescens, and also of VIM-4 in C. freundii. IncC plasmids were involved in the spread of the recently described VIM-86 in P. stuartii isolates. IncC plasmids carrying blaNDM-1 and blaVIM-86 were observed too. blaNDM-1 was also detected on IncX3 in S. marcescens and on IncT plasmid in M. morganii. The significant resistance transfer rates we observed highlight the role of the ESCPM group as a reservoir of resistance determinants and stress the need for strengthening infection control measures.

Klebsiella pneumoniae ST147: and then there were three carbapenemases

Gram-negative bacteria containing three different carbapenemases are extremely rare. Klebsiella pneumoniae (N22-925) with KPC-2, NDM-1, and OXA-48 was obtained from a Canadian patient with recent hospitalization in Romania. Short and long read whole genome sequencing showed that the bla_KPC-2 was situated on a 214 kb IncFIB(K)/IncFII(K) plasmid, the bla_NDM-1 on a 104 kb IncFIB (pQil)/IncFII(K) plasmid, and the bla_OXA-48 on a 64 kb IncL plasmid. These plasmids were conjugated to Escherichia coli J53. N22-925 belonged to a unique ST147 cluster that is likely endemic in Romania. This case emphasizes the need for rapid carbapenemase screening in patients from endemic regions. We described the first complete genome sequence of a K. pneumoniae isolate with three different carbapenemases, providing a reference for future studies on this rarely reported occurrence.

Genetic Characterization of bla NDM-1-Carrying Citrobacter portucalensis Sequence Type 328 and Citrobacter freundii Sequence Type 98

Purpose

NDM-1-producing Citrobacter portucalensis and Citrobacter freundii simultaneously occurred in a hospital. This study aims to characterize the bla_NDM-1-carrying plasmids in these Citrobacter strains.

Methods

Cf7303, Cf7308, and Cf7313 were recovered from three patients in a teaching hospital from September 24 to October 1, 2021. Bacteria were identified by MALDI-TOF mass spectrometry, and antibiotics susceptibility tests were determined by VITEK^® 2 compact system. Whole-genome sequencing (WGS) was performed using the HiSeq Illumina and QNome platform to characterize the genomes.

Results

Cf7303 was identified as C. portucalensis Sequence Type 328 by WGS, and harbored two plasmids, namely pCf7303 and a novel IncFIB pNDM-Cf7303 on which antibiotic-resistant genes (bla_TEM-1, bla_CTX-M-14, bla_NDM-1, aac (3)-IId, aadA2, fosA3, sul1, sul2, catA2, tetD, dfrA12, qacEdelta1, mph(A), and ble_MBL) are located. C. freundii strain Cf7308 and Cf7313 belonged to the same Sequence Type 98. Cf7308 contained two plasmids, pCf7308, and an IncN1 pNDM-Cf7308 with homology to pNDM-BTR in E. coli and pNDM-CWH001 in C. freundii.

Conclusion

We characterized a putatively novel IncFIB plasmid carrying bla_NDM-1 in C. portucalensis. In addition, the closely related bla_NDM-1-carrying IncN1 plasmids in E. coli and C. freundii suggest that interspecies or intraspecies horizontal transfer occurs in China.

Localized outbreaks of Pseudomonas aeruginosa belonging to international high-risk clones in a south Indian hospital

Introduction. Pseudomonas aeruginosa is now considered as a major bacterial pathogen associated with hospital infections. Frequently, multidrug-resistant (MDR) and extensively drug-resistant (XDR) P. aeruginosa are being encountered. Unusual increase in the P. aeruginosa infections led to the suspicion of outbreaks in the urology ward and cardiothoracic and vascular surgery intensive care unit (CTVS-ICU).Hypothesis. We hypothesize that the localized outbreaks may have originated from environmental sources within the hospital premises. An alternative possibility is the transmission from a previously infected patient or hospital attendant. Understanding the drug-resistance profile and genome characteristics of these clinical samples would determine the likely source of infection and spread.Aim. To perform epidemiological and molecular investigations on the suspected outbreaks of P. aeruginosa in the study centre and identify potential sources of infection.Methodology. Fourteen drug-resistant P. aeruginosa isolated from patients of the urology ward, CTVS-ICU and tap waters collected during the suspected outbreaks were subjected to microbiological and genomic analysis. Comparative genome (CG) analysis of these 14 study genomes with 284 complete P. aeruginosa genomes was performed.Results. Multilocus sequence typing analysis revealed that the isolates belonged to five different sequence types (ST235, ST357, ST639, ST654 and ST1203) and clustered into three distinct groups while two CTVS-ICU isolates remained as singletons. Genome analysis distinguished that the outbreaks in the urology ward and CTVS-ICU are independent, epidemiologically unrelated to each other and with the tap-water isolates.Conclusion. This study highlights the presence of distinct, clonally unrelated, drug-resistant P. aeruginosa within a hospital setting. The genome analysis of the two localized outbreaks revealed their distinct genetic background and phylogenetically unrelated origin. Vigilant screening and effective implementation of infection control measures led to the successful containment of potential environmental reservoirs of P. aeruginosa within the premises.

uCARE Chem Suite and uCAREChemSuiteCLI: Tools for bacterial resistome prediction

In the era of antibiotic resistance, in silico prediction of bacterial resistome profiles, likely to be associated with inactivation of new potential antibiotics is of utmost importance. Despite this, to the best of our knowledge, no tool exists for such prediction. Therefore, under the rationale that drugs with similar structures have similar resistome profiles, we developed two models, a deterministic model and a stochastic model, to predict the bacterial resistome likely to neutralize uncharacterized but potential chemical structures. The current version of the tool involves the prediction of a resistome for Escherichia coli and Pseudomonas aeruginosa. The deterministic model on omitting two diverse but relatively less characterized drug classes, polyketides and polypeptides showed an accuracy of 87%, a sensitivity of 85%, and a precision of 89%, whereas the stochastic model predicted antibiotic classes of the test set compounds with an accuracy of 72%, a sensitivity of 75%, and a precision of 83%. The models have been implemented in both a standalone package and an online server, uCAREChemSuiteCLI and uCARE Chem Suite, respectively. In addition to resistome prediction, the online version of the suite enables the user to visualize the chemical structure, classify compounds in 19 predefined drug classes, perform pairwise alignment, and cluster with database compounds using a graphical user interface.

Availability

uCARE Chem Suite can be browsed at: https://sauravsaha.shinyapps.io/ucarechemsuite2/, and uCAREChemSuiteCLI can be installed from:

1. CRAN (https://cran.r-project.org/package=uCAREChemSuiteCLI) and

2. GitHub (https://github.com/sauravbsaha/uCAREChemSuiteCLI).

Characterization of a blaNDM-1-carrying IncHI5 plasmid from Enterobacter cloacae complex of food-producing animal origin

OBJECTIVES

To characterize an NDM-1-encoding multiresistance IncHI5 plasmid from Enterobacter cloacae complex of chicken origin.

METHODS

Carbapenemase genes were detected by PCR and Sanger sequencing. The MICs for the E. cloacae complex isolate and its transformant were determined by the agar dilution and broth microdilution methods. Conjugation and electrotransformation were performed to assess the horizontal transferability of the carbapenemase plasmid. Plasmid DNA was isolated from the transformant and fully sequenced using Illumina HiSeq and PacBio platforms. Plasmid stability was investigated by sequential passages on antibiotic-free medium. A circular intermediate was detected by inverse PCR and Sanger sequencing.

RESULTS

Plasmid pNDM-1-EC12 carried a conserved IncHI5 backbone and exhibited an MDR phenotype. All antimicrobial resistance genes were clustered in a single MDR region. Genetic environment analysis revealed that the blaNDM-1 gene was in a novel complex integron, In469. Based on sequence analysis, the blaNDM-1-carrying region was thought to be inserted by homologous recombination. Inverse PCR indicated that an ISCR1-mediated circular intermediate can be formed. Plasmid pNDM-1-EC12 was stably maintained both in the parental strain and the transformant without selective pressure. Comprehensive analysis of IncHI5-type plasmids suggested that they may become another key vehicle for rapid transmission of carbapenemase genes.

CONCLUSIONS

To the best of our knowledge, this is the first report of a fully sequenced IncHI5 plasmid recovered from an E. cloacae complex strain of food-producing animal origin. Co-occurrence of blaNDM-1 with genes encoding resistance to other antimicrobial agents on the same IncHI5 plasmid may result in the co-selection of blaNDM-1 and facilitates its persistence and rapid dissemination.

Detection of diverse carbapenem and multidrug resistance genes and high-risk strain types among carbapenem non-susceptible clinical isolates of target gram-negative bacteria in Kenya

Carbapenem-resistant gram-negative bacteria are an increasingly significant clinical threat globally. This risk may be underestimated in Kenya as only four carbapenemase genes in three bacterial species have been described. The study aimed to understand the antibiotic resistance profiles, genes, sequence types, and distribution of carbapenem-resistant gram-negative bacteria from patients in six hospitals across five Kenyan counties by bacterial culture, antibiotic susceptibility testing, and whole-genome sequence analysis. Forty-eight, non-duplicate, carbapenem non-susceptible, clinical isolates were identified across the five counties (predominantly in Nairobi and Kisii): twenty-seven Acinetobacter baumannii, fourteen Pseudomonas aeruginosa, three Escherichia coli, two Enterobacter cloacae, and two Klebsiella pneumoniae. All isolates were non-susceptible to β-lactam drugs with variable susceptibility to tigecycline (66%), minocycline (52.9%), tetracycline (29.4%), and levofloxacin (22.9%). Thirteen P. aeruginosa isolates were resistant to all antibiotics tested. Eleven carbapenemase genes were identified: blaNDM-1, blaOXA-23, -58, -66, -69, and -91 in A. baumannii (STs 1, 2, 164 and a novel ST1475), blaNDM-1 in E. cloacae (STs 25,182), blaNDM-1, blaVIM-1and -6, blaOXA-50 in P. aeruginosa (STs 316, 357, 654, and1203), blaOXA-181, blaNDM-1 in K. pneumoniae (STs 147 and 219), and blaNDM-5 in E. coli (ST164). Five A. baumannii isolates had two carbapenemases, blaNDM-1, and either blaOXA-23 (4) or blaOXA-58 (1). AmpC genes were detected in A. baumannii (blaADC-25), E. cloacae (blaDHA-1 and blaACT-6, 16), and K. pneumoniae (blaCMY). Significant multiple-drug resistant genes were the pan-aminoglycoside resistance16srRNA methyltransferase armA, rmtB, rmtC, and rmtF genes. This study is the first to report blaOXA-420, -58, -181, VIM-6, and blaNDM-5 in Kenyan isolates. High-risk STs of A. baumannii (ST1475, ST2), E. cloacae ST182, K. pneumoniae ST147, P. aeruginosa (ST357, 654), and E. coli ST167, ST648 were identified which present considerable therapeutic danger. The study recommends urgent carbapenem use regulation and containment of high-risk carbapenem-resistant bacteria.

Mobile Carbapenemase Genes in Pseudomonas aeruginosa

Carbapenem-resistant Pseudomonas aeruginosa is one of the major concerns in clinical settings impelling a great challenge to antimicrobial therapy for patients with infections caused by the pathogen. While membrane permeability, together with derepression of the intrinsic beta-lactamase gene, is the global prevailing mechanism of carbapenem resistance in P. aeruginosa, the acquired genes for carbapenemases need special attention because horizontal gene transfer through mobile genetic elements, such as integrons, transposons, plasmids, and integrative and conjugative elements, could accelerate the dissemination of the carbapenem-resistant P. aeruginosa. This review aimed to illustrate epidemiologically the carbapenem resistance in P. aeruginosa, including the resistance rates worldwide and the carbapenemase-encoding genes along with the mobile genetic elements responsible for the horizontal dissemination of the drug resistance determinants. Moreover, the modular mobile elements including the carbapenemase-encoding gene, also known as the P. aeruginosa resistance islands, are scrutinized mostly for their structures.

Interplay between ESKAPE Pathogens and Immunity in Skin Infections: An Overview of the Major Determinants of Virulence and Antibiotic Resistance

The skin is the largest organ in the human body, acting as a physical and immunological barrier against pathogenic microorganisms. The cutaneous lesions constitute a gateway for microbial contamination that can lead to chronic wounds and other invasive infections. Chronic wounds are considered as serious public health problems due the related social, psychological and economic consequences. The group of bacteria known as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) are among the most prevalent bacteria in cutaneous infections. These pathogens have a high level of incidence in hospital environments and several strains present phenotypes of multidrug resistance. In this review, we discuss some important aspects of skin immunology and the involvement of ESKAPE in wound infections. First, we introduce some fundamental aspects of skin physiology and immunology related to cutaneous infections. Following this, the major virulence factors involved in colonization and tissue damage are highlighted, as well as the most frequently detected antimicrobial resistance genes. ESKAPE pathogens express several virulence determinants that overcome the skin's physical and immunological barriers, enabling them to cause severe wound infections. The high ability these bacteria to acquire resistance is alarming, particularly in the hospital settings where immunocompromised individuals are exposed to these pathogens. Knowledge about the virulence and resistance markers of these species is important in order to develop new strategies to detect and treat their associated infections.

Travel-Related Antimicrobial Resistance: A Systematic Review

There is increasing evidence that human movement facilitates the global spread of resistant bacteria and antimicrobial resistance (AMR) genes. We systematically reviewed the literature on the impact of travel on the dissemination of AMR. We searched the databases Medline, EMBASE and SCOPUS from database inception until the end of June 2019. Of the 3052 titles identified, 2253 articles passed the initial screening, of which 238 met the inclusion criteria. The studies covered 30,060 drug-resistant isolates from 26 identified bacterial species. Most were enteric, accounting for 65% of the identified species and 92% of all documented isolates. High-income countries were more likely to be recipient nations for AMR originating from middle- and low-income countries. The most common origin of travellers with resistant bacteria was Asia, covering 36% of the total isolates. Beta-lactams and quinolones were the most documented drug-resistant organisms, accounting for 35% and 31% of the overall drug resistance, respectively. Medical tourism was twice as likely to be associated with multidrug-resistant organisms than general travel. International travel is a vehicle for the transmission of antimicrobial resistance globally. Health systems should identify recent travellers to ensure that adequate precautions are taken.

Antimicrobials as Single and Combination Therapy for Colistin-Resistant Pseudomonas aeruginosa at a University Hospital in Thailand

Global infections with colistin-resistant Pseudomonas aeruginosa (CoR-PA) are increasing; there are currently very few studies focused on the antimicrobial susceptibility of CoR-PA isolates, and none from Thailand. Here, we investigated the impact of various antimicrobials, alone and in combination, via the in vitro testing of CoR-PA clinical isolates. Eighteen CoR-PA isolates were obtained from patients treated at Phramongkutklao Hospital from January 2010 through June 2019; these were classified into six different clonal types by using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method, with a high prevalence of Group A (27.8%). The antimicrobial susceptibility was determined as the minimal inhibitory concentrations (MICs) using the epsilometer-test (E-test) method. The synergistic activities of six antimicrobial combinations were reported via the fractional-inhibitory-concentration index. All CoR-PA isolates were susceptible to amikacin, meropenem, and ceftolozane/tazobactam, but only 5.56% were susceptible to imipenem. In vitro synergistic activities were detected for amikacin with aztreonam, piperacillin/tazobactam, meropenem, and ceftazidime for 16.67%, 11.11%, 11.11%, and 5.55%, respectively. One CoR-PA isolate carried the bla_VIM metallo-β-lactamase gene; none carried mcr-1 genes or detected plasmid-mediated AmpC β-lactamase or an overproduction of chromosomal AmpC β-lactamase. Seven CoR-PA isolates (38.89%) were capable of biofilm formation. In conclusion, CoR-PA isolates are highly susceptible to antimicrobials; the synergy observed in response to the various agents should be examined in a clinical setting.

Dissemination of VIM-producing Pseudomonas aeruginosa associated with high-risk clone ST654 in a tertiary and quaternary hospital in Makkah, Saudi Arabia

To the best of our knowledge, no molecular surveillance that has been conducted to identify the most common clones of carbapenem-resistant Pseudomonas aeruginosa (CRPA) in western Saudi Arabia. Therefore, this study aimed to identify genetic diversity and the most common CRPA clones in this region. Thirty-five CRPA isolates were collected from a tertiary and quaternary hospital in Makkah. bla _VIM was the most common carbapenemase-encoding gene (11 CRPA isolates), while bla_GES was reported in only three isolates. CRPA isolates were subjected to multi- locus sequence typing and showed relatively high genetic diversity with 20 sequence types. Approximately one-third (31.4%) of the CRPA isolates belonged to two high-risk clones (ST235 and ST654). This troublesome finding raises serious concerns about the emergence and further dissemination of CRPA high-risk clones in local hospitals and suggest that surveillance programs should be established in this region to monitor and control clonal dissemination of all multidrug resistant bacteria, including CRPA.

Role of Pseudomonas aeruginosa Glutathione Biosynthesis in Lung and Soft Tissue Infection

The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality worldwide. To survive in both the environment and the host, P. aeruginosa must cope with redox stress. In P. aeruginosa, a primary mechanism for protection from redox stress is the antioxidant glutathione (GSH). GSH is a low-molecular-weight thiol-containing tripeptide (l-γ-glutamyl-l-cysteinyl-glycine) that can function as a reversible reducing agent. GSH plays an important role in P. aeruginosa physiology and is known to modulate several cellular and social processes that are likely important during infection. However, the role of GSH biosynthesis during mammalian infection is not well understood. In this study, we created a P. aeruginosa mutant defective in GSH biosynthesis to examine how loss of GSH biosynthesis affects P. aeruginosa virulence. We found that GSH is critical for normal growth in vitro and provides protection against hydrogen peroxide, bleach, and ciprofloxacin. We also studied the role of P. aeruginosa GSH biosynthesis in four mouse infection models, including the surgical wound, abscess, burn wound, and acute pneumonia models. We discovered that the GSH biosynthesis mutant was slightly less virulent in the acute pneumonia infection model but was equally virulent in the three other models. This work provides new and complementary data regarding the role of GSH in P. aeruginosa during mammalian infection.

Genotypes, carbapenemase carriage, integron diversity and oprD alterations among carbapenem-resistant Pseudomonas aeruginosa from Russia

Pseudomonas aeruginosa is a serious opportunistic pathogen demonstrating a high level of resistance to many groups of antibiotics, including carbapenems. This study aimed to characterise the molecular epidemiology and prevalence of mobile genetic elements associated with resistance to carbapenems among P. aeruginosa (CRPA) clinical isolates. Among 145 carbapenem-resistant P. aeruginosa isolates, 34 different sequence types (STs) were detected; the six most common STs were ST654 (24%), ST235 (24%), ST111 (8%), ST446 (6%), ST357 (5%) and ST2592 (a novel single-locus variant of ST357) (4%). A carbapenemase gene was found in 94 isolates (64.8%). The bla_VIM-2 gene was harboured by 64 isolates (44.1%) restricted to ST111, ST235 and ST654, and the bla_GES-type and bla_OXA-10 group genes were each detected in 15 isolates (10.3%); none of other tested carbapenemase genes, including bla_IMP, bla_NDM and bla_GIM, were detected. Among the bla_VIM-2-positive isolates, five types of bla_VIM-2-containing integrons were discovered, including In56, In559, In59-like, In59 and In249. The oprD gene was disrupted by an insertion sequence (IS) in 15.9% of isolates. Overall, five types of IS elements were found (ISPsme1, ISPa1328, ISPa26, ISPst2 and ISPa195). Observed rearrangements within variable regions of bla_VIM-2-carrying integrons in conjunction with the discovery of a novel type of oprD-disrupting IS element illustrate the ongoing evolution of CRPA a, which warrants further investigation.

Isolation of five Enterobacteriaceae species harbouring blaNDM-1 and mcr-1 plasmids from a single paediatric patient

In Argentina, NDM metallo-β-lactamase was first reported in 2013. By now, it has disseminated throughout the country in diverse Gram negative bacteria. Here, we report the case of a paediatric patient that underwent a 1-year hospitalisation due to erythrodermic psoriasis in 2014 and received multiple antimicrobial treatments. During his stay, five isolates were obtained from rectal swabs (rs) or blood culture (bc) suspicious of carbapenemase production: a K. quasipneumoniae subsp. quasipneumoniae (rs), Citrobacter freundii (rs), Escherichia coli (bc), Enterobacter cloacae (rs), and a Serratia marcescens (bc). The isolates were studied with broth microdilution, biparental conjugation and plasmid and whole genome sequencing (Illumina). All isolates harboured an 138,998-bp type 1 IncC plasmid that carried bla_NDM-1, ble_MBL, bla_CMY-6, rmtC, aac(6’)-Ib, and sul1 resistance genes. Additionally, the bla_NDM-plasmids contained ISKpn8 an insertion sequence previously described as associated only to bla_KPC. One isolate, a colistin-resistant E. coli, also carried a mcr-1-containing an IncI2 plasmid, which did not harbour additional resistance. The whole genome of K. quasipneumoniae subsp. quasipneumoniae isolate was fully sequenced. This isolate harboured, additionally to bla_NDM, three plasmid-mediated quinolone resistance genes: qnrB4, qnrB52 and aac(6’)-Ib-cr1. The E. cloacae isolate also harboured qnrA1. These findings alert to the underestimated horizontal dissemination of multidrug-resistant plasmids limiting treatment options with last resort antimicrobials.

Characterization of a NDM-1- Encoding Plasmid pHFK418-NDM From a Clinical Proteus mirabilis Isolate Harboring Two Novel Transposons, Tn6624 and Tn6625

Acquisition of the bla_NDM–1 gene by Proteus mirabilis is a concern because it already has intrinsic resistance to polymyxin E and tigecycline antibiotics. Here, we describe a P. mirabilis isolate that carries a pPrY2001-like plasmid (pHFK418-NDM) containing a bla_NDM–1 gene. The pPrY2001-like plasmid, pHFK418-NDM, was first reported in China. The pHFK418-NDM plasmid was sequenced using a hybrid approach based on Illumina and MinION platforms. The sequence of pHFK418-NDM was compared with those of the six other pPrY2001-like plasmids deposited in GenBank. We found that the multidrug-resistance encoding region of pHFK418-NDM contains ΔTn10 and a novel transposon Tn6625. Tn6625 consists of ΔTn1696, Tn6260, In251, ΔTn125 (carrying bla_NDM–1), ΔTn2670, and a novel mph(E)-harboring transposon Tn6624. In251 was first identified in a clinical isolate, suggesting that it has been transferred efficiently from environmental organisms to clinical isolates. Genomic comparisons of all these pPrY2001-like plasmids showed that their relatively conserved backbones could integrate the numerous and various accessory modules carrying multifarious antibiotic resistance genes. Our results provide a greater depth of insight into the horizontal transfer of resistance genes and add interpretive value to the genomic diversity and evolution of pPrY2001-like plasmids.

Carbapenemases in Enterobacteriaceae: Detection and Antimicrobial Therapy

Carbapenem-resistant Enterobacteriaceae (CRE) have spread rapidly around the world in the past few years, posing great challenges to human health. The plasmid-mediated horizontal transmission of carbapenem-resistance genes is the main cause of the surge in the prevalence of CRE. Therefore, the timely and accurate detection of CRE, especially carbapenemase-producing Enterobacteriaceae, is very important for the clinical prevention and treatment of these infections. A variety of methods for the rapid detection of CRE phenotypes and genotypes have been developed for use in clinical microbiology laboratories. To overcome the lack of efficient antibiotics, CRE infections are often treated with combination therapies. Moreover, novel drugs and emerging strategies appeared successively and in various stages of development. In this article, we summarized the global distribution of various carbapenemases. And we focused on summarizing and comparing the advantages and limitations of the detection methods and the therapeutic strategies of CRE primarily.

Identification of two dihydrodipicolinate synthase isoforms from Pseudomonas aeruginosa that differ in allosteric regulation

Pseudomonas aeruginosa is one of the leading causes of nosocomial infections, accounting for 10% of all hospital-acquired infections. Current antibiotics against P. aeruginosa are becoming increasingly ineffective due to the exponential rise in drug resistance. Thus, there is an urgent need to validate and characterize novel drug targets to guide the development of new classes of antibiotics against this pathogen. One such target is the diaminopimelate (DAP) pathway, which is responsible for the biosynthesis of bacterial cell wall and protein building blocks, namely meso-DAP and lysine. The rate-limiting step of this pathway is catalysed by the enzyme dihydrodipicolinate synthase (DHDPS), typically encoded for in bacteria by a single dapA gene. Here, we show that P. aeruginosa encodes two functional DHDPS enzymes, PaDHDPS1 and PaDHDPS2. Although these isoforms have similar catalytic activities (k_cat  = 29 s^-1 and 44 s^-1 for PaDHDPS1 and PaDHDPS2, respectively), they are differentially allosterically regulated by lysine, with only PaDHDPS2 showing inhibition by the end product of the DAP pathway (IC₅₀  = 130 μm). The differences in allostery are attributed to a single amino acid difference in the allosteric binding pocket at position 56. This is the first example of a bacterium that contains multiple bona fide DHDPS enzymes, which differ in allosteric regulation. We speculate that the presence of the two isoforms allows an increase in the metabolic flux through the DAP pathway when required in this clinically important pathogen. DATABASES: PDB ID: 6P90.

Emergence of Carbapenem-Resistant Pseudomonas asiatica Producing NDM-1 and VIM-2 Metallo-β-Lactamases in Myanmar

Pseudomonas asiatica is a recently proposed species of the genus Pseudomonas This study describes eight isolates of carbapenem-resistant P. asiatica harboring bla _NDM-1 and bla _VIM-2, genes encoding metallo-β-lactamase (MBL). These isolates were obtained from urine samples of patients hospitalized in Myanmar. These isolates were resistant to carbapenems but susceptible to colistin. All eight isolates were positive for a carbapenemase inactivation method, CIMTrisII, and seven were positive on an immunochromatographic assay for NDM-type MBL. One isolate was highly resistant to aminoglycosides. Whole-genome sequencing showed that seven isolates harbored bla _NDM-1 and one harbored bla _VIM-2, with these genes located on the chromosome. One isolate harbored bla _NDM-1 and rmtC, a gene encoding 16S rRNA methylase. Five types of genomic environments surrounding bla _NDM-1 and bla _VIM-2 were detected in these eight isolates, with four isolates having the same type. These data indicate that P. asiatica isolates harboring genes encoding carbapenemases, including bla _NDM-1 and bla _VIM-2, are spreading in medical settings in Myanmar.

NDM Metallo-β-Lactamases and Their Bacterial Producers in Health Care Settings

New Delhi metallo-β-lactamase (NDM) is a metallo-β-lactamase able to hydrolyze almost all β-lactams. Twenty-four NDM variants have been identified in >60 species of 11 bacterial families, and several variants have enhanced carbapenemase activity. Klebsiella pneumoniae and Escherichia coli are the predominant carriers of bla _NDM, with certain sequence types (STs) (for K. pneumoniae, ST11, ST14, ST15, or ST147; for E. coli, ST167, ST410, or ST617) being the most prevalent. NDM-positive strains have been identified worldwide, with the highest prevalence in the Indian subcontinent, the Middle East, and the Balkans. Most bla _NDM-carrying plasmids belong to limited replicon types (IncX3, IncFII, or IncC). Commonly used phenotypic tests cannot specifically identify NDM. Lateral flow immunoassays specifically detect NDM, and molecular approaches remain the reference methods for detecting bla _NDM Polymyxins combined with other agents remain the mainstream options of antimicrobial treatment. Compounds able to inhibit NDM have been found, but none have been approved for clinical use. Outbreaks caused by NDM-positive strains have been reported worldwide, attributable to sources such as contaminated devices. Evidence-based guidelines on prevention and control of carbapenem-resistant Gram-negative bacteria are available, although none are specific for NDM-positive strains. NDM will remain a severe challenge in health care settings, and more studies on appropriate countermeasures are required.

Mobile Genetic Elements Associated with Antimicrobial Resistance

Strains of bacteria resistant to antibiotics, particularly those that are multiresistant, are an increasing major health care problem around the world. It is now abundantly clear that both Gram-negative and Gram-positive bacteria are able to meet the evolutionary challenge of combating antimicrobial chemotherapy, often by acquiring preexisting resistance determinants from the bacterial gene pool. This is achieved through the concerted activities of mobile genetic elements able to move within or between DNA molecules, which include insertion sequences, transposons, and gene cassettes/integrons, and those that are able to transfer between bacterial cells, such as plasmids and integrative conjugative elements. Together these elements play a central role in facilitating horizontal genetic exchange and therefore promote the acquisition and spread of resistance genes. This review aims to outline the characteristics of the major types of mobile genetic elements involved in acquisition and spread of antibiotic resistance in both Gram-negative and Gram-positive bacteria, focusing on the so-called ESKAPEE group of organisms (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), which have become the most problematic hospital pathogens.

Evolution and typing of IncC plasmids contributing to antibiotic resistance in Gram-negative bacteria

The large, broad host range IncC plasmids are important contributors to the spread of key antibiotic resistance genes and over 200 complete sequences of IncC plasmids have been reported. To track the spread of these plasmids accurate typing to identify the closest relatives is needed. However, typing can be complicated by the high variability in resistance gene content and various typing methods that rely on features of the conserved backbone have been developed. Plasmids can be broadly typed into two groups, type 1 and type 2, using four features that differentiate the otherwise closely related backbones. These types are found in many different countries in bacteria from humans and animals. However, hybrids of type 1 and type 2 are also occasionally seen, and two further types, each represented by a single plasmid, were distinguished. Generally, the antibiotic resistance genes are located within a small number of resistance islands, only one of which, ARI-B, is found in both type 1 and type 2. The introduction of each resistance island generates a new lineage and, though they are continuously evolving via the loss of resistance genes or introduction of new ones, the island positions serve as valuable lineage-specific markers. A current type 2 lineage of plasmids is derived from an early type 2 plasmid but the sequences of early type 1 plasmids include features not seen in more recent type 1 plasmids, indicating a shared ancestor rather than a direct lineal relationship. Some features, including ones essential for maintenance or for conjugation, have been examined experimentally.

Acquisition of resistance to carbapenem and macrolide-mediated quorum sensing inhibition by Pseudomonas aeruginosa via ICETn4371 6385

Pseudomonas aeruginosa can cause life-threatening infections in immunocompromised patients. The first-line agents to treat P. aeruginosa infections are carbapenems. However, the emergence of carbapenem-resistant P. aeruginosa strains greatly compromised the effectiveness of carbapenem treatment, which makes the surveillance on their spreading and transmission important. Here we characterized the full-length genomes of two carbapenem-resistant P. aeruginosa clinical isolates that are capable of producing New Delhi metallo-β-lactamase-1 (NDM-1). We show that bla_NDM-1 is carried by a novel integrative and conjugative element (ICE) ICE_Tn43716385, which also carries the macrolide resistance gene msr(E) and the florfenicol resistance gene floR. By exogenously expressing msr(E) in P. aeruginosa laboratory strains, we show that Msr(E) can abolish azithromycin-mediated quorum sensing inhibition in vitro and anti-Pseudomonas effect in vivo. We conclude that ICEs are important in transmitting carbapenem resistance, and that anti-virulence treatment of P. aeruginosa infections using sub-inhibitory concentrations of macrolides can be challenged by horizontal gene transfer.

Yichen Ding et al. identify a novel integrative and conjugative element that confers Pseudomonas aeruginosa with resistance to carbapenem, the last-resort drug for susceptable Gram-negative bacterial infections. This study also shows how antivirulence treatment for P. aeruginosainfections can be challenged by horizontal gene transfer.

Identification of carbapenem-resistant Pseudomonas aeruginosa in selected hospitals of the Gulf Cooperation Council States: dominance of high-risk clones in the region

PURPOSE

The molecular epidemiology and resistance mechanisms of carbapenem-resistant Pseudomonas aeruginosa (CRPA) were determined in hospitals in the countries of the Gulf Cooperation Council (GCC), namely, Saudi Arabia, the United Arab Emirates, Oman, Qatar, Bahrain and Kuwait.

METHODOLOGY

Isolates were screened for common carbapenem-resistance genes by PCR. Relatedness between isolates was assessed using previously described genotyping methods: an informative-single nucleotide polymorphism MassARRAY iPLEX assay (iPLEX20SNP) and the enterobacterial repetitive intergenic consensus (ERIC)-PCR assay, with selected isolates being subjected to multilocus sequence typing (MLST). Ninety-five non-repetitive isolates that were found to be resistant to carbapenems were subjected to further investigation.Results/Key findings. The most prevalent carbapenemase-encoding gene, blaVIM-type, was found in 37/95 (39 %) isolates, while only 1 isolate (from UAE) was found to have blaIMP-type. None of the CRPA were found to have blaNDM-type or blaKPC-type. We found a total of 14 sequence type (ST) clusters, with 4 of these clusters being observed in more than 1 country. Several clusters belonged to the previously recognized internationally disseminated high-risk clones ST357, ST235, ST111, ST233 and ST654. We also found the less predominant ST316, ST308 and ST823 clones, and novel MLST types (ST2010, ST2011, ST2012 and ST2013), in our collection.

CONCLUSION

Overall our data show that 'high-risk' CRPA clones are now detected in the region and highlight the need for strategies to limit further spread of such organisms, including enhanced surveillance, infection control precautions and further promotion of antibiotic stewardship programmes.

Molecular epidemiology of carbapenem-resistant Pseudomonas aeruginosa in an endemic area: comparison with global data

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is an endemic problem in certain countries including Greece. CRPA and multidrug-resistant P. aeruginosa (MDRPA) firstly emerged in our region during the 80s, right after the launch of imipenem and meropenem as therapeutic agents against P. aeruginosa infections. The role of outer membrane protein (Opr) inactivation has been known to contribute to imipenem resistance since many years, while efflux overexpression systems have been mainly associated with meropenem resistance. Among carbapenemases, metallo-β-lactamases (MBL) and mostly Verona integron-mediated (VIM) MBL's have played the most crucial role in CRPA emergence. VIM-2 and VIM-4 producing CRPA, usually belonging to clonal complexes (CC) 111 and 235 respectively, have most frequently been isolated. Bla_VIM-2 and bla_VIM-4 are usually associated with a class 1 integron. VIM-17 also has appeared in Greece. On the other hand, other VIM subtypes detected in a global level, such as VIM-3, VIM-5, VIM-6, VIM-7, VIM-11, VIM-14, VIM-15, VIM-16 and VIM-18 have not yet emerged in Greece. However, new VIM subtypes will probably emerge in the future. In addition, MBL carbapenemases other than VIM, detected worldwide have not yet appeared. A single CRPA isolate producing KPC has emerged in our region several years ago. The study of the molecular basis of Opr deficiency and efflux overexpression remains a challenge for the future. In this article, we review the molecular epidemiology of CRPA in an endemic area, compared to global data.

Pseudomonas aeruginosa: the history of one of the most successful nosocomial pathogens in Russian hospitals

Pseudomonas aeruginosa is recognized as one of the six most important pathogens in terms of antimicrobial resistance («ESKAPE» pathogens), and included by WHO in the group of microorganisms for which the need for development of new antimicrobial agents is crucial. In 2015, P. aeruginosa was the second (after Klebsiella spp.) most common nosocomial bacterial pathogen in Russia with the following resistance rates: amikacin – 45.2%, imipenem – 51.5%, meropenem – 53.3%, colistin – 2.2%, piperacillin/tazobactam – 61.4%, ceftazidime – 56.8%, ciprofloxacin – 61.2%. The majority of carbapenemase-producing isolates in Russia belong to the two epidemic lineages – CC235 and CC654.

Structural genomics of pNDM-BTR harboring In191 and Tn6360, and other bla NDM-carrying IncN1 plasmids

Aim: To characterize a conjugative bla NDM-1-carrying plasmid pNDM-BTR from a clinical Escherichia coli isolate. Materials & methods: The complete nucleotide sequence of pNDM-BTR was determined using next-generation sequencing technology. Comparative genomic analysis of bla NDM-carrying IncN1 plasmids, including pNDM-BTR, was performed, and the antimicrobial resistance phenotypes were determined. Results: pNDM-BTR contained three accessory modules, namely IS26, a novel Tn3-family transposon Tn6360 and the dfrA14 region composed of In191, ecoRII–ecoRIImet and ΔIS1X2. The relatively small IncN1 backbones could integrate massive accessory modules, most of which were integrated at two ‘hotspots’. These IncN1 plasmids contained distinct profiles of accessory modules, which included those carrying various resistance genes. Conclusion: This study provides a deeper insight into horizontal transfer of resistance genes among IncN1 plasmids.

Resistance to Antibiotics, Biocides, Preservatives and Metals in Bacteria Isolated from Seafoods: Co-Selection of Strains Resistant or Tolerant to Different Classes of Compounds

Multi-drug resistant bacteria (particularly those producing extended-spectrum β-lactamases) have become a major health concern. The continued exposure to antibiotics, biocides, chemical preservatives, and metals in different settings such as the food chain or in the environment may result in development of multiple resistance or co-resistance. The aim of the present study was to determine multiple resistances (biocides, antibiotics, chemical preservatives, phenolic compounds, and metals) in bacterial isolates from seafoods. A 75.86% of the 87 isolates studied were resistant to at least one antibiotic or one biocide, and 6.90% were multiply resistant to at least three biocides and at least three antibiotics. Significant (P < 0.05) moderate or strong positive correlations were detected between tolerances to biocides, between antibiotics, and between antibiotics with biocides and other antimicrobials. A sub-set of 30 isolates selected according to antimicrobial resistance profile and food type were identified by 16S rDNA sequencing and tested for copper and zinc tolerance. Then, the genetic determinants for biocide and metal tolerance and antibiotic resistance were investigated. The selected isolates were identified as Pseudomonas (63.33%), Acinetobacter (13.33%), Aeromonas (13.33%), Shewanella, Proteus and Listeria (one isolate each). Antibiotic resistance determinants detected included sul1 (43.33% of tested isolates), sul2 (6.66%), blaTEM (16.66%), blaCTX-M (16.66%), blaPSE (10.00%), blaIMP (3.33%), blaNDM-1 (3.33%), floR (16.66%), aadA1 (20.0%), and aac(6')-Ib (16.66%). The only biocide resistance determinant detected among the selected isolates was qacEΔ1 (10.00%). A 23.30 of the selected isolates were able to grow on media containing 32 mM copper sulfate, and 46.60% on 8 mM zinc chloride. The metal resistance genes pcoA/copA, pcoR, and chrB were detected in 36.66, 6.66, and 13.33% of selected isolates, respectively. Twelve isolates tested positive for both metal and antibiotic resistance genes, including one isolate positive for the carbapenemase gene blaNDM-1 and for pcoA/copA. These results suggest that exposure to metals could co-select for antibiotic resistance and also highlight the potential of bacteria on seafoods to be involved in the transmission of antimicrobial resistance genes.

Pseudomonas aeruginosa Lifestyle: A Paradigm for Adaptation, Survival, and Persistence

Pseudomonas aeruginosa is an opportunistic pathogen affecting immunocompromised patients. It is known as the leading cause of morbidity and mortality in cystic fibrosis (CF) patients and as one of the leading causes of nosocomial infections. Due to a range of mechanisms for adaptation, survival and resistance to multiple classes of antibiotics, infections by P. aeruginosa strains can be life-threatening and it is emerging worldwide as public health threat. This review highlights the diversity of mechanisms by which P. aeruginosa promotes its survival and persistence in various environments and particularly at different stages of pathogenesis. We will review the importance and complexity of regulatory networks and genotypic-phenotypic variations known as adaptive radiation by which P. aeruginosa adjusts physiological processes for adaptation and survival in response to environmental cues and stresses. Accordingly, we will review the central regulatory role of quorum sensing and signaling systems by nucleotide-based second messengers resulting in different lifestyles of P. aeruginosa. Furthermore, various regulatory proteins will be discussed which form a plethora of controlling systems acting at transcriptional level for timely expression of genes enabling rapid responses to external stimuli and unfavorable conditions. Antibiotic resistance is a natural trait for P. aeruginosa and multiple mechanisms underlying different forms of antibiotic resistance will be discussed here. The importance of each mechanism in conferring resistance to various antipseudomonal antibiotics and their prevalence in clinical strains will be described. The underlying principles for acquiring resistance leading pan-drug resistant strains will be summarized. A future outlook emphasizes the need for collaborative international multidisciplinary efforts to translate current knowledge into strategies to prevent and treat P. aeruginosa infections while reducing the rate of antibiotic resistance and avoiding the spreading of resistant strains.

Identification of IncA/C Plasmid Replication and Maintenance Genes and Development of a Plasmid Multilocus Sequence Typing Scheme

Plasmids of incompatibility group A/C (IncA/C) are becoming increasingly prevalent within pathogenic Enterobacteriaceae They are associated with the dissemination of multiple clinically relevant resistance genes, including bla_CMY and bla_NDM Current typing methods for IncA/C plasmids offer limited resolution. In this study, we present the complete sequence of a bla_NDM-1-positive IncA/C plasmid, pMS6198A, isolated from a multidrug-resistant uropathogenic Escherichia coli strain. Hypersaturated transposon mutagenesis, coupled with transposon-directed insertion site sequencing (TraDIS), was employed to identify conserved genetic elements required for replication and maintenance of pMS6198A. Our analysis of TraDIS data identified roles for the replicon, including repA, a toxin-antitoxin system; two putative partitioning genes, parAB; and a putative gene, 053 Construction of mini-IncA/C plasmids and examination of their stability within E. coli confirmed that the region encompassing 053 contributes to the stable maintenance of IncA/C plasmids. Subsequently, the four major maintenance genes (repA, parAB, and 053) were used to construct a new plasmid multilocus sequence typing (PMLST) scheme for IncA/C plasmids. Application of this scheme to a database of 82 IncA/C plasmids identified 11 unique sequence types (STs), with two dominant STs. The majority of bla_NDM-positive plasmids examined (15/17; 88%) fall into ST1, suggesting acquisition and subsequent expansion of this bla_NDM-containing plasmid lineage. The IncA/C PMLST scheme represents a standardized tool to identify, track, and analyze the dissemination of important IncA/C plasmid lineages, particularly in the context of epidemiological studies.

The rapid spread of carbapenem-resistant Enterobacteriaceae

Carbapenems, our one-time silver bullet for multidrug resistant bacterial infections, are now threatened by widespread dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Successful expansion of Enterobacteriaceae clonal groups and frequent horizontal gene transfer of carbapenemase expressing plasmids are causing increasing carbapenem resistance. Recent advances in genetic and phenotypic detection facilitate global surveillance of CRE diversity and prevalence. In particular, whole genome sequencing enabled efficient tracking, annotation, and study of genetic elements colocalized with carbapenemase genes on chromosomes and on plasmids. Improved characterization helps detail the co-occurrence of other antibiotic resistance genes in CRE isolates and helps identify pan-drug resistance mechanisms. The novel β-lactamase inhibitor, avibactam, combined with ceftazidime or aztreonam, is a promising CRE treatment compared to current colistin or tigecycline regimens. To halt increasing CRE-associated morbidity and mortality, we must continue quality, cooperative monitoring and urgently investigate novel treatments.