Genetic Characterization of Carbapenem-Resistant Enterobacteriaceae and the Spread of Carbapenem-Resistant Klebsiella pneumonia ST340 at a University Hospital in Thailand

Characterisation of Non-Carbapenemase-Producing Carbapenem-Resistant Klebsiella pneumoniae Based on Their Clinical and Molecular Profile in Malaysia

Non-carbapenemase-producing carbapenem-resistant Klebsiella pneumoniae (NC-CRKP) confers carbapenem resistance through a combination of chromosomal mutations and acquired non-carbapenemase resistance mechanisms. In this study, we aimed to evaluate the clinical and molecular profiles of NC-CRKP isolated from patients in a tertiary teaching hospital in Malaysia from January 2013 to October 2019. During the study period, 54 NC-CRKP-infected/colonised patients’ isolates were obtained. Clinical parameters were assessed in 52 patients. The all-cause in-hospital mortality rate among NC-CRKP patients was 46.2% (24/52). Twenty-three (44.2%) patients were infected, while others were colonised. Based on the Charlson Comorbidity Index (CCI) score, 92.3% (48/52) of the infected/colonised patients had a score of ≥ 1. Resistance genes found among the 54 NC-CRKP isolates were bla_TEM, bla_SHV, bla_CTX-M, bla_OXA, and bla_DHA. Porin loss was detected in 25/54 (46.3%) strains. None of the isolated strains conferred carbapenem resistance through the efflux pumps system. In conclusion, only 25/54 (46.3%) NC-CRKP conferred carbapenem resistance through a combination of porin loss and the acquisition of non-carbapenemase resistance mechanisms. The carbapenem resistance mechanisms for the remaining strains (53.7%) should be further investigated as rapid identification and distinction of the NC-CRKP mechanisms enable optimal treatment and infection control efforts.

An Overview on Phenotypic and Genotypic Characterisation of Carbapenem-Resistant Enterobacterales

Improper use of antimicrobials has resulted in the emergence of antimicrobial resistance (AMR), including multi-drug resistance (MDR) among bacteria. Recently, a sudden increase in Carbapenem-resistant Enterobacterales (CRE) has been observed. This presents a substantial challenge in the treatment of CRE-infected individuals. Bacterial plasmids include the genes for carbapenem resistance, which can also spread to other bacteria to make them resistant. The incidence of CRE is rising significantly despite the efforts of health authorities, clinicians, and scientists. Many genotypic and phenotypic techniques are available to identify CRE. However, effective identification requires the integration of two or more methods. Whole genome sequencing (WGS), an advanced molecular approach, helps identify new strains of CRE and screening of the patient population; however, WGS is challenging to apply in clinical settings due to the complexity and high expense involved with this technique. The current review highlights the molecular mechanism of development of Carbapenem resistance, the epidemiology of CRE infections, spread of CRE, treatment options, and the phenotypic/genotypic characterisation of CRE. The potential of microorganisms to acquire resistance against Carbapenems remains high, which can lead to even more susceptible drugs such as colistin and polymyxins. Hence, the current study recommends running the antibiotic stewardship programs at an institutional level to control the use of antibiotics and to reduce the spread of CRE worldwide.

Prevalence and incidence of carbapenem-resistant K. pneumoniae colonization: systematic review and meta-analysis

BACKGROUND

Klebsiella pneumoniae is a gram-negative rod belonging to the order Enterobacterales and having a wide distribution in the environment, including the human colon. Recently, the bacterium is one of the known problems in the healthcare setting as it has become resistant to last-resort drugs like carbapenems. The colonized person can serve as a reservoir for his/herself and others, especially in the healthcare setting leading to nosocomial and opportunistic infections. Therefore, we aimed to quantitatively estimate the rate of prevalence and incidence of colonization with carbapenem-resistant K. pneumoniae.

METHODS

A literature search was conducted on PubMed/MEDLINE, Google Scholar, Science Direct, Cochrane Library, WHO Index Medicus, and university databases. The study includes all published and unpublished papers that addressed the prevalence or incidence of K. pneumoniae colonization. Data were extracted onto format in Microsoft Excel and pooled estimates with a 95% confidence interval calculated using Der-Simonian-Laird random-effects model. With the use of I² statistics and prediction intervals, the level of heterogeneity was displayed. Egger's tests and funnel plots of standard error were used to demonstrate the publication bias.

RESULTS

A total of 35 studies were included in the review and 32 records with 37,661 patients for assessment of prevalence, while ten studies with 3643 patients for incidence of colonization. The prevalence of carbapenem-resistant K. pneumoniae colonization varies by location and ranges from 0.13 to 22%, with a pooled prevalence of 5.43%. (3.73-7.42). Whereas the incidence of colonization ranges from 2 to 73% with a pooled incidence of 22.3% (CI 12.74-31.87), both prevalence and incidence reports are majorly from developed countries. There was a variation in the distribution of carbapenem resistance genes among colonizing isolates with KPC as a prominent gene reported from many studies and NDM being reported mainly by studies from Asian countries. A univariate meta-regression analysis indicated continent, patient type, study design, and admission ward do not affect the heterogeneity (p value>0.05).

CONCLUSION

The review revealed that colonization with K. pneumoniae is higher in a healthcare setting with variable distribution in different localities, and resistance genes for carbapenem drugs also have unstable distribution in different geographic areas.

Active Surveillance for Carbapenem-Resistant Enterobacterales (CRE) Colonization and Clinical Course of CRE Colonization among Hospitalized Patients at a University Hospital in Thailand

Optimal measures for preventing and controlling carbapenem-resistant Enterobacterales (CRE) depend on their burden. This prospective observational study investigated the prevalence and clinical course of CRE colonization in hospitalized patients at Siriraj Hospital, the largest university hospital in Thailand. Stool/rectal swab samples were collected from the patients upon admission, once weekly during hospitalization and every 1–3 months after discharge, to determine the presence of CRE in the stool. Between 2018 and 2021, a total of 528 patients were included. The prevalence of CRE colonization upon admission was 15.5%, while 28.3% of patients who tested negative for CRE on admission acquired CRE during their hospitalization. CRE colonization upon admission was usually associated with prior healthcare exposure. Among CRE-colonized patients, 4.7% developed a CRE clinical infection, with 60% mortality. No cutoff period that ensured that patients were free of CRE colonization in stool was identified, and isolation precautions should only be ceased if stool tests are negative for CRE. In conclusion, the prevalence of CRE colonization among hospitalized patients at Siriraj Hospital is high. CRE-colonized patients are at risk of developing subsequent CRE infection. To prevent CRE transmission within the hospital, patients at high risk of colonization should undergo CRE screening upon admission.

Association Between Types of Carbapenemase and Clinical Outcomes of Infection Due to Carbapenem Resistance Enterobacterales

Purpose

Compared with non-carbapenemase producing carbapenem-resistant Enterobacterales (non-CP-CRE), carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) are associated with considerable mortality. However, given that the patients are treated with various therapeutic options, it remains unclear whether differences in types of carbapenemase genes yield different mortality rates. Therefore, this study aims to identify carbapenemase genes and identify whether clinical outcomes differ according to the prevalence of genotype and phenotype of carbapenemase among Enterobacterales clinical isolated.

Patients and Methods

A retrospective cohort study was performed to determine whether types of carbapenemase genes have an impact on clinical outcomes. Carbapenem-resistant clinical isolates were collected at a tertiary care university hospital in Songkhla, Thailand, between June 2018 and February 2020. Demographic and microbiological data such as antimicrobial susceptibility, carbapenemase genes, and overall mortality were evaluated.

Results

A total of 121 Enterobacterales clinical isolated were evaluated. The bla_NDM-1 gene was detected in 44% of the isolates, followed by bla_OXA-48 (28%) and bla_NDM-1/OXA-48 (28%). NDM-1- or NDM-1/OXA-48- producing isolates were more likely to require meropenem MICs of ≥16 mg/L, while OXA-48-producing isolates were more likely to require meropenem MICs of <16 mg/L. The patients with NDM-1 or NDM-1/OXA-48 had a higher 14 days mortality rate than those with OXA-48 after treating with carbapenem-containing regimens (P-value 0.001) or colistin-containing regimens (P-value < 0.001).

Conclusion

Our findings suggest that the mortality for CP-CRE infection in patients with NDM-1 or NDM-1/OXA-48 was higher than the mortality in those with OXA-48, which It seems that the type of carbapenemase gene may affect meropenem MIC levels. Hence, in treatment decisions involving the use of either carbapenem-containing regiment or colistin-containing regiment in patients with CP-CRE infection, especially those in the NDM-1 and NDM-1/OXA-48 groups, the patient symptoms should be closely monitored.

Multi Evaluation of a Modified GoldNano Carb Test for Carbapenemase Detection in Clinical Isolates of Gram-Negative Bacilli

Carbapenemase-producing Gram-negative bacteria have been increasingly reported. Simple and sensitive methods for carbapenemase detection are still needed. In this study, a gold nanoparticle (AuNP) solution was modified by the addition of zinc sulfate (ZnSO4) for improving the conventional GoldNano Carb (cGoldC) test, and the modified GoldC (mGoldC) test was then evaluated for phenotypic detection of carbapenemase production in Gram-negative bacilli clinical isolates. ZnSO4 was added to give final concentrations of 0.25, 0.5, 0.75, and 1 mM. The performance of the mGoldC test was evaluated in Enterobacterales, Acinetobacter spp., and Pseudomonas aeruginosa isolates from six hospitals in different regions using polymerase chain reaction (PCR) as a gold standard. The AuNP solution with 0.25 mM ZnSO4 was used for the mGoldC test. Evaluation of the mGoldC test in 495 Enterobacterales, 212 Acinetobacter spp., and 125 P. aeruginosa isolates (including 444 carbapenemase producers and 388 non-carbapenemase producers) revealed sensitivity, specificity, a positive likelihood ratio, and a negative likelihood ratio of 98.6%, 98.2%, 54.7, and 0.01, respectively. This test is fast, easy to perform, cost-effective (~0.25 USD per test), and highly sensitive and specific for routine carbapenemase detection, thus leading to effective antimicrobial therapy and infection control measures.

Nationwide surveillance in Thailand revealed genotype-dependent dissemination of carbapenem-resistant Enterobacterales

Carbapenem-resistant Enterobacterales (CRE) are a serious public health threat because of their rapid dissemination. To determine the epidemiological and genetic characteristics of CRE infections in Thailand, we performed whole-genome sequencing of 577 carbapenem-resistant Klebsiella pneumoniae isolates and 170 carbapenem-resistant Escherichia coli isolates from hospitals across the nation. The four most prevalent carbapenemase genes harboured by these bacteria were bla NDM-1, bla NDM-5, bla OXA-181 and bla OXA-232. The gene bla NDM-1 was identified in diverse sequence types. The gene bla NDM-5 was identified almost exclusively in E. coli . The genes bla OXA-181, bla OXA-232, and co-carriage of bla NDM-1 and bla OXA-232 were found in specific sequence types from certain provinces. Replicon typing revealed the diverse backbones of bla NDM-1- and bla NDM-5-harbouring plasmids and successful expansion of bla NDM-1-harbouring IncN2-type plasmids. Core-genome single-nucleotide polymorphism analysis suggested that bla OXA-181-, bla OXA-232-, bla NDM-5-, and co-carriage of bla NDM-1 and bla OXA-232-associated sub-clonal lineages have recently predominated in the provinces from where these isolates were isolated. Thus, we demonstrate genotype-dependent dissemination of CRE in Thailand, which is helpful for establishing infection-control strategies in CRE-endemic areas.

Endophytic Fungus from Opuntia ficus-indica: A Source of Potential Bioactive Antimicrobial Compounds against Multidrug-Resistant Bacteria

Endophytic Aspergillus species represent an inexhaustible source for many medicinally important secondary metabolites. The current study isolated the endophytic Aspergillus niger (OL519514) fungus from Opuntia ficus-indica fruit peels. The antibacterial activities were reported for both Aspergillus species and Opuntia ficus-indica fruit peel extract. Extraction of the endophytic fungal metabolites using ethyl acetate and fractionation was performed, yielding dihydroauroglaucin (C1), isotetrahydroauroglaucin (C2), and cristatumin B (C3). Resistant bacterial strains were used to investigate the efficiency of the total fungal ethyl acetate extract (FEA) and the isolated compounds. FEA showed promising wide spectrum activity. (C3) showed excellent activity against selected Gram-negative resistant bacteria; However, (C2) exhibited tremendous activity against the tested Gram-positive resistant strains; conversely, (C1) possessed the lowest antibacterial activity compared to the two other compounds. An in silico virtual molecular docking demonstrated that cristatumin B was the most active antimicrobial compound against the selected protein targets. In conclusion, the active metabolites newly isolated from the endophytic fungus Aspergillus niger (OL519514) and present in plants' waste can be a promising antimicrobial agent against multidrug-resistant bacteria.

Antimicrobial Activity Profiles and Potential Antimicrobial Regimens against Carbapenem-Resistant Enterobacterales Isolated from Multi-Centers in Western Thailand

The spread of carbapenem-resistant Enterobacterales (CRE) constitutes a global health burden. Antimicrobial susceptibility and types of carbapenemase differ by geographic region. This study aimed to (1) examine the minimum inhibitory concentrations (MICs) and antibiotic resistance genes and (2) investigate antibiotic dosing regimens against CRE using Monte Carlo simulation. Clinical carbapenem-resistant Klebsiella pneumoniae (CRKP), Escherichia coli (CREC), and Enterobacter cloacae (CREclo) isolates were collected from various hospitals in western Thailand. Broth microdilution was performed, and the types of carbapenemase and mcr-1 genes were detected using polymerase chain reaction (PCR). Monte Carlo simulation was used to establish optimal antimicrobial dosing regimens meeting the criterion of a cumulative fraction of response (CFR) >90%. A total of 150 CRE isolates from 12 hospitals were included. The proportion of CRKP (76%) was greater than that of CREC (22%) and CREclo (2%). Regional hospitals reported higher rates of resistance than general hospitals. Most isolates were resistant to aztreonam and ceftazidime/avibactam, whereas they were highly susceptible to aminoglycosides. Most carbapenemases were NDM (47.33%), OXA-48 (43.33%) and NDM plus OXA-48 (6.67%); five OXA-48 positive isolates carried mcr-1 genes. Currently, high-dose tigecycline is the only optimal regimen against CRE isolates. Further extensive research on antibiotic synergism or new antibiotics should be conducted.

Impact of Carbapenem Heteroresistance Among Multidrug-Resistant ESBL/AmpC-Producing Klebsiella pneumoniae Clinical Isolates on Antibiotic Treatment in Experimentally Infected Mice

Purpose

Antibiotic resistance is a growing health crisis that is further complicated by treatment failures caused by bacteria that exhibit heterogeneous susceptibility to antibiotics. The aim of this study was to describe imipenem (IPM)-heteroresistant strains among multidrug-resistant (MDR) ESBL/AmpC-producing Klebsiella pneumoniae clinical isolates, investigate their molecular phenotypic characteristics, and elucidate the outcome of antibiotic treatment in mice infected with the heteroresistant isolates.

Materials and Methods

Antimicrobial susceptibility of K. pneumoniae isolates was determined by the disk diffusion and E-test methods. Heteroresistance to IPM was confirmed by population analysis profile (PAP) assays. PCR and sequencing were employed to detect MDR determinants. Molecular differences between the susceptible and resistant subpopulations were evaluated by sequencing and quantitative real-time reverse transcription PCR (qRT-PCR) analysis. The effect of the carbapenem-heteroresistant strains on antibiotic treatment was assessed using a mouse model of peritonitis with heteroresistant K. pneumoniae and subsequent treatment with IPM.

Results

In total, 37 MDR ESBL/AmpC-producing clinical isolates of K. pneumoniae were identified between September 2018 and December 2019. These strains were notably resistant to conventional antimicrobials other than carbapenems. Among the isolates, three strains exhibited heteroresistance to IPM and carried several ESBL and/or AmpC genes. Mice infected with a lethal dose of any of the three heteroresistant isolates were unable to survive in the presence of IPM treatment, as the percentage of the IPM-resistant subpopulation of each strain was increased in the peritoneum of these mice at 24 h after infection. The resistant subpopulation of the strains presented pulsed-field gel electrophoresis (PFGE) profiles that were identical to those of the susceptible subpopulation, but ompK36 porin showed a reduction in gene expression (0.09- to 0.50-fold) in the resistant subpopulation.

Conclusion

Carbapenem-heteroresistant strains were present among the MDR K. pneumoniae isolates producing ESBL/AmpC β-lactamases, and these heteroresistant strains failed IPM therapy in experimentally infected mice.

Genomic investigation of a suspected Klebsiella pneumoniae outbreak in a neonatal care unit in sub-Saharan Africa

A special-care neonatal unit from a large public hospital in Malawi was noted as having more frequent, difficult-to-treat infections, and a suspected outbreak of multi-drug-resistant Klebsiella pneumoniae was investigated using genomic characterisation. All K. pneumoniae bloodstream infections (BSIs) from patients in the neonatal ward (n=62), and a subset of K. pneumoniae BSI isolates (n=38) from other paediatric wards in the hospital, collected over a 4 year period were studied. After whole genome sequencing, the strain sequence types (STs), plasmid types, virulence and resistance genes were identified. One ST340 clone, part of clonal complex 258 (CC258) and an ST that drives hospital outbreaks worldwide, harbouring numerous resistance genes and plasmids, was implicated as the likely cause of the outbreak. This study contributes molecular information necessary for tracking and characterizing this important hospital pathogen in sub-Saharan Africa.

Concurrent Resistance to Carbapenem and Colistin Among Enterobacteriaceae Recovered From Human and Animal Sources in Nigeria Is Associated With Multiple Genetic Mechanisms

Resistance to last resort drugs such as carbapenem and colistin is a serious global health threat. This study investigated carbapenem and colistin resistance in 583 non-duplicate Enterobacteriaceae isolates utilizing phenotypic methods and whole genome sequencing (WGS). Of the 583 isolates recovered from humans, animals and the environment in Nigeria, 18.9% (110/583) were resistant to at least one carbapenem (meropenem, ertapenem, and imipenem) and 9.1% (53/583) exhibited concurrent carbapenem-colistin resistance. The minimum inhibitory concentrations of carbapenem and colistin were 2–32 μg/mL and 8 to >64 μg/mL, respectively. No carbapenem resistant isolates produced carbapenemase nor harbored any known carbapenemase producing genes. WGS supported that concurrent carbapenem-colistin resistance was mediated by novel and previously described alterations in chromosomal efflux regulatory genes, particularly mgrB (M1V) ompC (M1_V24del) ompK37 (I70M, I128M) ramR (M1V), and marR (M1V). In addition, alterations/mutations were detected in the etpA, arnT, ccrB, pmrB in colistin resistant bacteria and ompK36 in carbapenem resistant bacteria. The bacterial isolates were distributed into 37 sequence types and characterized by the presence of internationally recognized high-risk clones. The results indicate that humans and animals in Nigeria may serve as reservoirs and vehicles for the global spread of the isolates. Further studies on antimicrobial resistance in African countries are warranted.

High-Level Carbapenem Resistance among OXA-48-Producing Klebsiellapneumoniae with Functional OmpK36 Alterations: Maintenance of Ceftazidime/Avibactam Susceptibility

The aim of this work was to analyze outer membrane porin-encoding genes (ompK35 and ompK36) in a collection of OXA-48 producing Klebsiella pneumoniae, to assess the effect of porin alterations on the susceptibility to ceftazidime/avibactam, and to describe a screening methodology for phenotypic detection of OXA-48-producing K. pneumoniae with disrupted porins. Antimicrobial susceptibility was tested by Microscan and Etest. The genomes of 81 OXA-48-producing K. pneumoniae were sequenced. MLST, detection of antimicrobial resistance genes, and analysis of ompK35 and ompK36 were performed in silico. Tridimensional structures of the OmpK36 variants were assessed. Receiver operating characteristics curves were built to visualize the performance ability of a disk diffusion assay using carbapenems and cefoxitin to detect OmpK36 functional alterations. A wide variety of OmpK36 alterations were detected in 17 OXA-48-producing K. pneumoniae isolates. All displayed a high-level meropenem resistance (MIC ≥ 8 mg/L), and some belonged to high-risk clones, such as ST15 and ST147. Alterations in ompK35 were also observed, but they did not correlate with high-level meropenem resistance. All isolates were susceptible to ceftazidime/avibactam and porin alterations did not affect the MICs of the latter combination. Cefoxitin together with ertapenem/meropenem low inhibition zone diameters (equal or lower than 16 mm) could strongly suggest alterations affecting OmpK36 in OXA-48-producing K. pneumoniae. OXA-48-producing K. pneumoniae with porin disruptions are a cause of concern; ceftazidime/avibactam showed good in vitro activity against them, so this combination could be positioned as the choice therapy to combat the infections caused by this difficult-to-treat isolates.

Antibiotic Resistance Genes Among Carbapenem-resistant Enterobacterales (CRE) Isolates of Prapokklao Hospital, Chanthaburi Province, Thailand

Background

The global spread of carbapenem-resistant Enterobacterales (CRE) inflicts a severe threat to human health. The CRE infections have resulted in an increased mortality rate in hospitals and other health-care settings worldwide. In this study, the antibiotic-resistance pattern and prevalence of carbapenemase-encoding genes among CRE isolated from patients of one hospital in Thailand were investigated.

Methods

By using conventional biochemical tests, we identified and isolated all species of Enterobacterales from the clinical samples kept at Prapokklao Hospital, Chanthaburi, Thailand, which were collected during 2016–2017. Multidrug-resistant (MDR) bacteria were determined by disc diffusion method and minimum inhibitory concentration (MIC) test strips. Carbapenemase genes were detected by PCR and confirmed by Sanger sequencing.

Results

Klebsiella pneumoniae complex, Escherichia coli, and Enterobacter spp. were isolated from the specimens. Of 9,564 isolated Enterobacterales, 282 were multidrug-resistance (MDR). The MIC test strips revealed that the MDR CRE were resistant to ertapenem (92.9%) and meropenem (81.3%). All these isolates carried carbapenemase-coding genes, including bla_NDM (90%) and bla_IMP (71%), the two most commonly found genes among CRE strains. There were 39.2% of the isolates that carried a combination of bla_NDM-bla_IMP and 22.6% carried combined bla_NDM-bla_IMP-bla_OXA-48-like genes.

Conclusion

This study demonstrates a significantly high prevalence of CRE isolates with the MDR phenotypes. A minority of the isolates carried a single carbapenem-resistant gene, while the majority harbored multiple genes in combination. Regular monitoring of MDR CRE and characterization of their drug resistance are important for guiding treatment, intervention and control of the CRE spread and outbreak in a health-care setting.

Genetyping of Carbapenem-resistant Organisms Isolated from Clinical Isolates Received from Tertiary Care Hospitals of Ahmedabad, Gujarat

The world is seeing a continuous rise in the levels of antibiotic resistance1. Organisms develop new resistance mechanisms, emerge, and spread the resistance worldwide, making it challenging to treat common infectious diseases. In the current study, clinical isolates received between the years 2017 to 2020 were cultured and the isolated organisms were screened for antibiotic resistance; isolates with multiple drug resistance were further subjected to confirmatory screening through Combined Disc Test (CDT) and Modified Hodge Test (M.H.T.), and molecular characterization to be finally tested for gene expression analysis. Molecular characterization involved screening of genes blaVIM-2, blaKPC-3, blaNDM-1, and blaIMP-11 responsible for imparting carbapenem drug resistance2. From the laboratories of tertiary care hospitals, a total of 1452 clinical isolates were collected and identified. The organisms were subjected to antibiotic susceptibility screening and carbapenem resistance screening. The isolates found positive in the screenings were subjected to molecular characterization for genes, blaVIM-2, blaKPC-3, blaNDM-1, and blaIMP-11, responsible for imparting carbapenem drug resistance. Most of the isolates were resistant variably to aminoglycosides but were found to be resistant to fluoroquinolones and β-lactams group of antibiotics. Carbapenem activity was detected in twelve percent of total isolates and 27 percent among multidrug-resistant isolates. blaNDM-1 gene was found present in 77% isolates, and five organisms among the total number of organisms showed pan drug resistance.

Optical DNA Mapping of Plasmids Reveals Clonal Spread of Carbapenem-Resistant Klebsiella pneumoniae in a Large Thai Hospital

Carbapenem-resistant Klebsiella pneumoniae (CR-KP) in patients admitted to hospitals pose a great challenge to treatment. The genes causing resistance to carbapenems are mostly found in plasmids, mobile genetic elements that can spread easily to other bacterial strains, thus exacerbating the problem. Here, we studied 27 CR-KP isolates collected from different types of samples from 16 patients admitted to the medical ward at Siriraj Hospital in Bangkok, Thailand, using next generation sequencing (NGS) and optical DNA mapping (ODM). The majority of the isolates belonged to sequence type (ST) 16 and are described in detail herein. Using ODM, we identified the plasmid carrying the bla_NDM-1 gene in the ST16 isolates and the plasmids were very similar, highlighting the possibility of using ODM of plasmids as a surrogate marker of nosocomial spread of bacteria. We also demonstrated that ODM could identify that the bla_CTX-M-15 and bla_OXA-232 genes in the ST16 isolates were encoded on separate plasmids from the bla_NDM-1 gene and from each other. The other three isolates belonged to ST147 and each of them had distinct plasmids encoding bla_NDM-1.

Synergistic Antibacterial Effects of Meropenem in Combination with Aminoglycosides against Carbapenem-Resistant Escherichia coli Harboring blaNDM-1 and blaNDM-5

Infections due to carbapenem-resistant Escherichia coli (CREC) are problematic due to limitation in treatment options. Combination therapies of existing antimicrobial agents have become a reliable strategy to control these infections. In this study, the synergistic effects of meropenem in combination with aminoglycosides were assessed by checkerboard and time-kill assays. Of the 35 isolates, 19 isolates (54.3%) were resistant to carbapenems (imipenem and meropenem) with the MIC ranges from 16 to 128 µg/mL. These isolates were resistant to almost all antibiotic classes. Molecular characteristics revealed co-harboring of carbapenemase (bla_NDM-1, bla_NDM-5 and bla_OXA-48) and extended-spectrum β-lactamases (ESBL) genes (bla_CTX-M, bla_SHV and bla_TEM). The checkerboard assay displayed synergistic effects of meropenem and several aminoglycosides against most CREC isolates. Time-kill assays further demonstrated strong synergistic effects of meropenem in combination with either amikacin, gentamicin, kanamycin, streptomycin, and tobramycin. The results suggested that meropenem in combination with aminoglycoside therapy might be an efficient optional treatment for infections cause by CREC.

Nationwide Surveillance and Molecular Characterization of Critically Drug-Resistant Gram-Negative Bacteria: Results of the Research University Network Thailand Study

A large-scale surveillance is an important measure to monitor the regional spread of antimicrobial resistance. We prospectively studied the prevalence and molecular characteristics of clinically important Gram-negative bacilli, including Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii complex (ABC), and Pseudomonas aeruginosa, from blood, respiratory tract, urine, and sterile sites at 47 hospitals across Thailand. Among 187,619 isolates, 93,810 isolates (50.0%) were critically drug resistant, of which 12,915 isolates (13.8%) were randomly selected for molecular characterization. E. coli was most commonly isolated from all specimens, except the respiratory tract, in which ABC was predominant. Prevalence of extended-spectrum cephalosporin resistance (ESCR) was higher in E. coli (42.5%) than K. pneumoniae (32.0%), but carbapenem-resistant (CR)-K. pneumoniae (17.2%) was 4.5-fold higher than CR-E. coli (3.8%). The majority of ESCR/CR-E. coli and K. pneumoniae isolates carried bla_CTX-M (64.6% to 82.1%). bla_NDM and bla_OXA-48-like were the most prevalent carbapenemase genes in CR-E. coli/CR-K. pneumoniae (74.9%/52.9% and 22.4%/54.1%, respectively). In addition, 12.9%/23.0% of CR-E. coli/CR-K. pneumoniae cocarried bla_NDM and bla_OXA-48-like. Among ABC isolates, 41.9% were extensively drug resistant (XDR) and 35.7% were multidrug resistant (MDR), while P. aeruginosa showed XDR/MDR at 6.3%/16.5%. A. baumannii was the most common species among ABC isolates. The major carbapenemase gene in MDR-A. baumannii/XDR-A. baumannii was bla_OXA-23-like (85.8%/93.0%), which had much higher rates than other ABC species. bla_IMP, bla_VIM, bla_OXA-40-like, and bla_OXA-58-like were also detected in ABC at lower rates. The most common carbapenemase gene in MDR/XDR-P. aeruginosa was bla_IMP (29.0%/30.6%), followed by bla_VIM (9.5%/25.3%). The findings reiterate an alarming situation of drug resistance that requires serious control measures.

The Potential Use of Ceftazidime-Avibactam Against Carbapenem Resistant Klebsiella pneumoniae Clinical Isolates Harboring Different Carbapenemase Types in a Thai University Hospital

Purpose

MBL and OXA-48 genes in carbapenem-resistant Enterobacterales (CRE) have emerged as a major public health problem worldwide, including Thailand. Due to the lack of susceptibility data and dosing regimens of ceftazidime-avibactam (CZA) against CRE in Thailand, especially in colistin-resistant era, we aimed to demonstrate in vitro susceptibility data of CZA and optimal dose based on Monte Carlo simulation of CZA to expand the treatment options.

Patients and Methods

We collected 49 carbapenem-resistant Klebsiella pneumoniae (CRKP) clinical isolates from unique patients at Phramongkutklao Hospital (June–October 2020). CZA disk diffusion and E-test testing were performed to obtain minimum inhibitory concentration (MIC). Each drug regimen was simulated using the Monte Carlo technique to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR).

Results

The most common genotypes of CRKP were bla_OXA-48 (53.1%) and bla_OXA-48 +bla_NDM (42.8%). CZA showed 47.7% and 90.5% susceptible rate against all genotypes of carbapenemases and OXA-48 type CRKP isolates. The MIC₅₀ and MIC₉₀ of CZA against CRKP were 2 and >256 µg/mL. The categorical agreement (CA) between disk diffusion and E-test testing of CZA against CRKP was 95.4%. The CZA dosing regimens of 2.5 g infused 2–3 h every 8 h achieved ≥90% of the target of free ceftazidime plasma concentration over MIC (%fTime >MIC) ≥50% and 100% against isolates MICs of ≤8 and ≤8 µg/mL, respectively. The avibactam regimens also provided 100%fTime at 0.5 µg/mL. Based on CFR ≥90%, no CZA regimens were effective against all of the studied CRKP isolates except CRKP carrying OXA-48.

Conclusion

CZA exhibited a fairly susceptible rate among the OXA-48-positive isolates in Thailand. The current suggested dose of CZA with prolonged infusion appears appropriate to achieve the pharmacokinetic/pharmacodynamic targets of ceftazidime and avibactam against CRKP carrying bla_OXA-48.

Genomic and clinical characterisation of multidrug-resistant carbapenemase-producing ST231 and ST16 Klebsiella pneumoniae isolates colonising patients at Siriraj hospital, Bangkok, Thailand from 2015 to 2017

BACKGROUND

Infections caused by carbapenemase-producing Enterobacteriaceae (CPE) have continually grown as a global public health threat, with significant mortality rates observed across the world. We examined the clinical data from patients with CPE infections and their outcomes, concentrating on Klebsiella pneumoniae isolates. We analysed the clinical information, performed antimicrobial susceptibility testing, and conducted molecular epidemiological and genomic analyses on the isolates to identify patterns in the data.

METHODS

The clinical characteristics of 33 hospitalised patients with confirmed CPE, including patient-related factors associated with the development of CPE infections, were examined. Patients were divided according to whether they were "colonised" or "infected" with CPE and by the timing and frequency of their rectal swab collections, from which 45 swabs were randomly selected for analysis. CPE isolates were purified, and antimicrobial susceptibility tests performed. Whole genome sequences of these isolates were determined and analysed to compute bacterial multilocus sequence types and plasmid replicon types, infer phylogenetic relationships, and identify antimicrobial resistance and virulence genes.

RESULTS

Altogether, 88.9% (40/45) of the CPE isolates were K. pneumoniae. The most abundant carbapenemase gene family in the K. pneumoniae isolates (33/39) was bla_OXA-232, with bla_NDM-1 additionally identified in 19 of them. All CPE isolates carrying either bla_OXA-232 or bla_NDM-1 were resistant to meropenem, but only 40 from 45 were susceptible to colistin. Among the CPE-infected patients (n = 18) and CPE-colonised patients who developed CPE infections during the study (n = 3), all but one received standard colistin-based combination therapy. Phylogenetic analysis revealed the polyclonal spread of carbapenemase-producing K. pneumoniae (CPKP) within the patient population, with the following two major subclades identified: ST16 (n = 15) and ST231 (n = 14). CPKP-ST231 had the highest virulence score of 4 and was associated with primary bacteraemia. The siderophores yersiniabactin and aerobactin, considered to be important virulence factors, were only identified in the CPKP-ST231 genomes.

CONCLUSIONS

This study has revealed the genomic features of colonising CPE isolates, focusing on antimicrobial resistance and virulence determinants. This type of multi-layered analysis can be further exploited in Thailand and elsewhere to modify the regimes used for empirical antibiotic treatment and improve the management strategies for CPE infections in hospitalised patients.

Carriage of Carbapenem-Resistant Enterobacterales in Adult Patients Admitted to a University Hospital in Italy

The emerging spread of carbapenemase-producing Enterobacterales (CPE) strains, in particular, Klebsiella pneumoniae and Escherichia coli, has become a significant threat to hospitalized patients. Carbapenemase genes are frequently located on plasmids than can be exchanged among clonal strains, increasing the antibiotic resistance rate. The aim of this study was to determine the prevalence of CPE in patients upon their admission and to analyze selected associated factors. An investigation of the antibiotic resistance and genetic features of circulating CPE was carried out. Phenotypic tests and molecular typing were performed on 48 carbapenemase-producing strains of K. pneumoniae and E. coli collected from rectal swabs of adult patients. Carbapenem-resistance was confirmed by PCR detection of resistance genes. All strains were analyzed by PCR-based replicon typing (PBRT) and multilocus sequence typing (MLST) was performed on a representative isolate of each PBRT profile. More than 50% of the strains were found to be multidrug-resistant, and the bla_KPC gene was detected in all the isolates with the exception of an E. coli strain. A multireplicon status was observed, and the most prevalent profile was FIIK, FIB KQ (33%). MLST analysis revealed the prevalence of sequence type 512 (ST512). This study highlights the importance of screening patients upon their admission to limit the spread of CRE in hospitals.

Detection of carbapenem-resistance genes in bacteria isolated from wastewater in Ontario

Bacterial carbapenem resistance is a major public health concern since these antimicrobials are often the last resort to treat serious human infections. To evaluate methodologies for detection of carbapenem resistance, carbapenem-tolerant bacteria were isolated from wastewater treatment plants in Toronto, Ottawa, and Arnprior, Ontario. A total of 135 carbapenem-tolerant bacteria were recovered. Polymerase chain reaction (PCR) indicated the presence of carbapenem hydrolysing enzymes KPC ( n = 10), GES ( n = 5), VIM ( n = 7), and IMP ( n = 1), and β-lactamases TEM ( n = 7), PER ( n = 1), and OXA-variants ( n = 16). A subset of 46 isolates were sequenced and analysed using ResFinder and CARD-RGI. Both programs detected carbapenem resistance genes in 35 sequenced isolates and antimicrobial resistance genes (ARGs) conferring resistance to multiple class of other antibiotics. Where β-lactamase resistance genes were not initially identified, lowering the thresholds for ARG detection enabled identification of closely related β-lactamases. However, no known carbapenem resistance genes were found in seven sequenced Pseudomonas spp. isolates. Also of note was a multi-drug-resistant Klebsiella pneumoniae isolate from Ottawa, which harboured resistance to seven antimicrobial classes including β-lactams. These results highlight the diversity of genes encoding carbapenem resistance in Ontario and the utility of whole genome sequencing over PCR for ARG detection where resistance may result from an assortment of genes.

The present danger of New Delhi metallo-β-lactamase: a threat to public health

The evolution of antimicrobial-resistant Gram-negative pathogens is a substantial menace to public health sectors, notably in developing countries because of the scarcity of healthcare facilities. New Delhi metallo-β-lactamase (NDM) is a potent β-lactam enzyme able to hydrolyze several available antibiotics. NDM was identified from the clinical isolates of Klebsiella pneumoniae and Escherichia coli from a Swedish patient in New Delhi, India. This enzyme horizontally passed on to various Gram-negative bacteria developing resistance against a variety of antibiotics which cause treatment crucial. These bacteria increase fatality rates and play an integral role in the economic burden. The efficient management of NDM-producing isolates requires the coordination between each healthcare setting in a region. In this review, we present the prevalence of NDM in children, fatality and the economic burden of resistant bacteria, the clonal spread of NDM harboring bacteria and modern techniques for the detection of NDM producing pathogens.

Molecular insights of Carbapenem resistance Klebsiella pneumoniae isolates with focus on multidrug resistance from clinical samples

BACKGROUND

Carbapenem are the last-line antibiotic, defence against Gram-negative extended spectrum ß-lactamases producers (ESBLs). Carbapenem resistance Enterobacteriaceae especially Carbapenem resistant-Klebsiella pneumoniae (CR-KP) is recognized as one of the well-known public health problem, which is increasingly being reported around the world. The present study was focused to analyse the prevalence and characterization of antibiotic resistance K. pneumoniae in centre region of Tamil Nadu, India.

METHODOLOGY

Totally 145 suspected K. pneumoniae isolates [Urine, Pus, Sputum, Blood and Biopsy] obtained from hospitals of Central South India. The isolates were subjected to biochemical and molecular identification technique, following with antibiotic resistance pattern by standard antibiotic sensitivity test. Multidrug resistance (MDR) with β-lactamase producing Carbapenem resistant K. pneumoniae (CR-KP) strains were screened by classical sensitivity method and also drug resistance encoded gene. Also, molecular typing of the MDR strains were characterized by Pulsed-Field Gel Electrophoresis (PFGE). Further, the outer membrane protein (OmpK35 and 36) related Carbapenem resistance were characterized.

RESULTS

Totally, 61% of isolates were confirmed as K. pneumoniae, 75 % of isolates were MDR including 58% carbapenem and 97% ESBL antibiotics and grouped into 17 distinct resistant patterns. The MDR KP isolates shows positive for blaCTXM-1 (92 %) gene followed by blaSHV (43 %), blaTEM (36 %), blaNDM-1 (26 %), blaGES (20 %) and blaIMP-1 (8 %). Moreover, 62 % CR-KP isolates loses OmpK36 and 33% isolates loses OmpK35.

CONCLUSIONS

Loss of OmpK36 were highly an influence the cefoxitin and carbapenem resistance. Sixteen different PFGE patterns have been observed among the 18 MDR isolates. Eventually, ESBL as well as CR-KP were diverse in genetic makeup and often associated with hyper virulence hvKP should be of serious concern.

In vitro synergistic activity of fosfomycin in combination with other antimicrobial agents against carbapenem-resistant Klebsiella pneumoniae isolated from patients in a hospital in Thailand

INTRODUCTION

Carbapenem-resistant Klebsiella pneumoniae (CRKP) causes high morbidity and mortality worldwide. The purpose of the study was to assess the synergistic activity of fosfomycin in combination with other antimicrobial agents against CRKP isolated from patients in Songklanagarind Hospital, Thailand.

METHODS

A total of 35 K. pneumoniae isolates were obtained from patients in Songklanagarind Hospital. The MICs of imipenem and meropenem were determined in all isolates by broth microdilution. In all CRKP isolates, the presence of carbapenemase and extended-spectrum β-lactamase (ESBL) genes was investigated by PCR, while the production of these enzymes was determined by combined disk test. In the carbapenemase-genes-negative CRKP isolates, the porin loss and efflux pump were characterized by SDS-PAGE and broth microdilution, respectively. Finally, the synergistic effects of fosfomycin and other antimicrobial agents were evaluated by checkerboard analysis.

RESULTS

Twenty-one of 35 K. pneumoniae isolates were classified as CRKP. Most of CRKP isolates carried bla_NDM-1 (n = 18), bla_SHV (n = 21), bla_CTX-M (n = 21), and bla_TEM (n = 16). In fosfomycin-based combination, the result showed that the highest synergistic activity in this study was observed in the combination of fosfomycin and gentamicin (61.9%).

CONCLUSION

These findings suggested that the fosfomycin and gentamicin combination might be useful as a possible treatment option for CRKP infection.

Bacteremia Caused by Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Vientiane, Lao PDR: A 5-Year Study

Although there has been an increasing incidence of bacteremia caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) across South East Asia, there are sparse data from the Lao PDR, where laboratory capacity for antimicrobial resistance surveillance is limited. We, therefore, retrospectively reviewed bacteremia caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae between 2010 and 2014 at Mahosot Hospital, Vientiane, Lao PDR. Clinical and laboratory data relating to all episodes of ESBL-E bacteremia were reviewed over the 5-year period and compared with non-ESBL-E bacteremia. Blood cultures positive for E. coli or K. pneumoniae were identified retrospectively from laboratory records. Clinical and laboratory data were extracted from research databases and case notes and analyzed using STATA. Between 2010 and 2014, we identified 360 patients with E. coli (n = 249) or K. pneumoniae (n = 111) bacteremia, representing 34.8% of all patients with clinically significant bacteremia. Seventy-two (20%) isolates produced ESBL; E. coli accounted for 15.3% (55/360) and K. pneumoniae for 4.7% (17/360), respectively. The incidence of ESBL-producing E. coli bacteremia rose during the study period. By multiple logistic analysis, reported antibiotic use in the previous week was significantly associated with ESBL positivity (P < 0.001, odds ratio 3.89). Although multiresistant, most ESBL-producing E. coli and K. pneumoniae remained susceptible to meropenem (65/65; 100%) and amikacin (64/65; 98.5%). We demonstrated an alarming increase in the incidence of ESBL-E as a cause of bacteremia in Vientiane during the study period. This has implications for empiric therapy of sepsis in Laos, and ongoing surveillance is essential.

An African perspective on the prevalence, fate and effects of carbapenem resistance genes in hospital effluents and wastewater treatment plant (WWTP) final effluents: A critical review

This article provides an overview of the antibiotic era and discovery of earliest antibiotics until the present day state of affairs, coupled with the emergence of carbapenem-resistant bacteria. The ways of response to challenges of antibiotic resistance (AR) such as the development of novel strategies in the search of new antibiotics, designing more effective preventive measures as well as the ecology of AR have been discussed. The applications of plant extract and chemical compounds like nanomaterials which are based on recent developments in the field of antimicrobials, antimicrobial resistance (AMR), and chemotherapy were briefly discussed. The agencies responsible for environmental protection have a role to play in dealing with the climate crisis which poses an existential threat to the planet, and contributes to ecological support towards pathogenic microorganisms. The environment serves as a reservoir and also a vehicle for transmission of antimicrobial resistance genes hence, as dominant inhabitants we have to gain a competitive advantage in the battle against AMR.

Genomic characterization of an emerging blaKPC-2 carrying Enterobacteriaceae clinical isolates in Thailand

The rapidly increasing prevalence of carbapenem-resistant Enterobacteriaceae (CRE) over the past decade has increased concern in healthcare facilities and the impact on public health. The prevalence of bla_KPC (KPC) in Thailand remains very low; only bla_KPC-13 has been described previously. This study is the first to describe the characteristics of bla_KPC-2-carrying Klebsiella pneumoniae, Escherichia coli, and Enterobacter asburiae in Thailand. The prevalence rate of bla_KPC-2-carrying isolates was 0.13% among CRE isolates in our study. Based on carbapenem susceptibility testing, K. pneumoniae C1985 was resistant to meropenem and ertapenem, E. coli C1992 was resistant to meropenem, imipenem, and ertapenem, and E. asburiae C2135 was only resistant to imipenem. K. pneumoniae C1985 carried bla_KPC-2, bla_SHV-11, fosA, oqxA, and oqxB, while E. coli C1992 contained bla_KPC-2 and mdf(A) and E. asburiae C2135 harbored bla_KPC-2, bla_ACT-2, and qnrE1. The genetic features of bla_KPC-2 in the 3 isolates revealed identical rearrangement and flanking regions. Analysis of genomic sequences from these 3 isolates revealed that the sequence types of K. pneumoniae C1985, E. coli C1992, and E. asburiae C2135 were ST4008, ST7297, and ST1249, respectively. The 3 bla_KPC-2 isolates were from individual living cases. Two cases were colonization for K. pneumoniae C1985 and E. asburiae C2135 and the third case was hospital-acquired infection of E. coli C1992. Although the prevalence of bla_KPC-2-carrying CRE is relatively low in this study, continued surveillance and close monitoring are warranted. In addition, prompt or early detection of CRE and strict implementation of infection control are essential to prevent outbreaks or rapid spread in hospitals.

Clonal dissemination of KPC-2-producing Klebsiella pneumoniae ST11 and ST48 clone among multiple departments in a tertiary teaching hospital in Jiangsu Province, China

Background

The world-wide prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a threat to the public health. The objective of this study was to determine the epidemiological and molecular patterns of KPC-producing Klebsiella pneumoniae (K. pneumoniae) clinical isolates.

Methods

In this study, a total of 82 non-duplicated CRKP isolates were analyzed for the prevalence of resistant determinants including carbapenemase, extended spectrum β-lactamase (ESBLs), and AmpC as well as integrons and cassette regions by polymerase chain reaction (PCR) and DNA sequencing. The genetic relatedness was investigated by pulsed field gel electrophoresis (PFGE) and multi-locus sequencing typing (MLST).

Results

Overall, bla _KPC-2 (n=75) was the predominant carbapenemase gene, followed by high prevalence of bla _SHV (92.7%) and bla _CTX-M (90.2%). PFGE and MLST analysis revealed that 65 out of 68 KPC-2-producing CRKP belonged to the ST11 clone and were distributed mainly in the department of neurology ICU. Moreover, first report on clonal dissemination of KPC-2-producing CRKP ST48 clone and NDM-5-producing CRKP ST337 clone was also identified. Class I integron were detected in 17 (20.7%) of 82 isolates with aadA2 being the most common cassette. And a novel cassette array of integron, aac(6')-II-bla _CARB/PSE-1 was identified.

Conclusions

All in all, KPC-2-producing CRKP ST11 and ST48 clone were widely disseminated in multiple departments of our hospital, which triggers the need for active surveillance and implementation of infection control measures.

Outbreak Of Klebsiella pneumoniae Carbapenemase-Producing Klebsiella aerogenes Strains In A Tertiary Hospital In China

Purpose

This study aimed to evaluate the molecular characteristics and prevalence of clinical carbapenem-resistant Klebsiella aerogenes (CRKA), collected during an outbreak in a Chinese tertiary hospital.

Methods

Antimicrobial susceptibility test, using 17 antibiotics, was performed on 14 CRKA isolates. The strains were examined for the presence of β-lactamase genes by PCR, and efflux pump phenotype was determined by efflux pump inhibition test. Presence of outer-membrane porins was examined. Clonal relatedness among the isolates was investigated by pulsed-field gel electrophoresis (PFGE). S1 nuclease-PFGE and plasmid incompatibility group analysis were performed to determine plasmids, and the genetic environment of bla_KPC-2 was analyzed. Epidemiological data were collected via chart review.

Results

The 14 CRKA isolates were all resistant to carbapenems; five distinct groups (PFGE types A–E) were observed. All 14 isolates carried the bla_KPC-2 gene. S1 nuclease-PFGE indicated the size of bla_KPC-2-carrying plasmids to range from 20 kb to 200 kb, and the 14 plasmids belonged to various incompatibility groups. The most frequent genetic environment of bla_KPC-2 was Tn1721- bla_KPC-2-ΔTn3-IS26. PFGE type A group, including 11 KPC-2-producing clinical isolates, was primarily responsible for dissemination.

Conclusion

Our findings suggest both transposons and vertical transmission to contribute to the transformation of bla_KPC-2. The results strongly suggest strict implementation of infection control of CRKA, in healthcare facilities.

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Epidemiology of carbapenem-resistant Enterobacteriaceae: a 5-year experience at a tertiary care hospital

Purpose

The incidence of carbapenem-resistant Enterobacteriaceae (CRE) has been increasing worldwide. Ertapenem resistance is mediated by non-carbapenemase mechanisms, and has less of an effect on susceptibility to imipenem and meropenem. This study aimed to study the epidemiology of CRE, and to compare risk factors and related mortality between non-susceptibility to ertapenem alone Enterobacteriaceae (NSEE), with non-susceptibility to other carbapenems (imipenem, meropenem, or doripenem) Enterobacteriaceae (NSOCE) at a tertiary care hospital in Thailand.

Methods

All CRE isolated were identified between December 2011 and December 2016. Quarterly incidence rate was estimated. Hospital-wide carbapenem consumption was calculated as defined daily doses (DDD). Relationships between hospital-wide carbapenem consumption and incidence of CRE were tested. Factors associated with NSEE and NSOCE, and risk factors associated with 14- and 30-day mortality in patients with CRE infection were determined.

Results

The quarterly CRE incidence increased significantly from 3.37 per 100,000 patient-days in the last quarter of 2011 to 32.49 per 100,000 patient-days in the last quarter of 2016. (P for trend <0.001). Quarterly hospital-wide carbapenem consumption increased 1.58 DDD per 1,000 patient-days (P for trend=0.004). The Poisson regression showed the expected increase of CRE incidence was 1.02 per 100,000 patient-days for a 1 DDD per 1,000 patient-days increase in carbapenem consumption (P<0.001). There were 40 patients with NSEE and 134 patients with NSOCE in the 5-year study period. The NSEE group had significantly lower carbapenem exposure compared with the NSOCE group (adjusted odds ratio: 0.25; P=0.001). No difference in 14-day and 30-day all-cause mortality between the two groups was observed.

Conclusion

The incidence of CRE has risen significantly at our institution. Previous carbapenem use was associated with NSOCE. This hospital-wide carbapenem use was significantly associated with the increasing incidence of CRE.

Correlation between antimicrobial consumption and the prevalence of carbapenem-resistant Escherichia coli and carbapenem-resistant Klebsiella pneumoniae at a university hospital in Thailand

WHAT IS KNOWN AND OBJECTIVE

Carbapenem-resistant Enterobacteriaceae (CRE) are virulent gram-negative bacilli and cause urgent healthcare problems worldwide. One of the main factors leading to the emergence of CRE is antimicrobial consumption. The objective of this study was to assess how closely the rate of antimicrobial consumption and the prevalences of carbapenem-resistant Escherichia coli (CR-EC) and carbapenem-resistant Klebsiella pneumoniae (CR-KP) are correlated.

METHODS

A retrospective study was performed at a university hospital in Thailand from January 2013 to September 2016. The prevalence of E coli and K pneumoniae was represented as percentages per species per quarter. The antimicrobial consumption rate per quarter was expressed as the defined daily dose (DDD)/1000 patient-days. Evaluation of the relationships between the rate of antimicrobial consumption and the prevalences of CR-EC and CR-KP was conducted via Pearson's or Spearman's correlation analyses.

RESULTS AND DISCUSSION

During the study period, the prevalence of CR-EC and CR-KP was less than 6%; however, significantly increasing prevalences were reported for both CR-EC (r = 0.55, P = 0.03) and CR-KP (r = 0.87, P < 0.01). There was a significant increasing trend in the consumption of meropenem (r = 0.65, P = 0.01), levofloxacin (r = 0.63, P = 0.01), ceftriaxone (r = 0.55, P = 0.03), ertapenem (r = 0.52, P = 0.05) and the carbapenem group (r = 0.64, P = 0.01). A significant correlation was observed between CR-KP prevalence and total carbapenem consumption (r = 0.55, P = 0.04). Moreover, levofloxacin consumption had a significant positive relationship with the prevalence of CR-KP (r = 0.65, P = 0.01). No positive correlation was found with the prevalence of CR-EC.

WHAT IS NEW AND CONCLUSION

The rate of consumption of levofloxacin and carbapenems was the important key factor correlated with the rate of emergence of CR-KP. This is the first report demonstrating the correlation between levofloxacin consumption and CR-KP prevalence.

Molecular characterization and epidemiology of carbapenem non-susceptible Enterobacteriaceae isolated from the Eastern region of Heilongjiang Province, China

Background

The aim of this study was to elucidate the molecular epidemiology of carbapenem non-susceptible Enterobacteriaceae(CNSE) isolated in the Eastern region of Heilongjiang Province, China, and the mechanism of carbapenem resistance.

Methods

A total of 53 CNSE isolates were collected in a grade-3 hospital in Heilongjiang province. Sensitivity to antibiotics was determined using the VITEK-2 Compact automatic system. The modified Hodge test (MHT) and modified carbapenem inactivation test (mCIM) were performed for phenotypic identification. Beta-lactamases gene were detected by Polymerase chain reaction(PCR) and DNA sequencing. The transfer of bla_NDM and bla_KPC was investigated through conjugation experiment. The clinical data of patients were retrospectively reviewed. Homology of Carbapenem-resistant Klebsiella pneumoniae(CRKP) was conducted by multilocus sequence typing (MLST).

Results

CNSE were highly resistant to the majority of antimicrobial agents. The resistance rate was 100% for first, third, fourth generation cephalosporins and enzyme inhibitor compounds. Gentamicin and tobramycin recorded a resistance rate higher than 80%. Less than 30% resistance was detected for amikacin and levofloxacin. Among CNSE 52(98.1%) and 48(90.6%) of CNSE were positive for mCIM and MHT respectively. There were 42 positive bla_KPC genes, three bla_NDM-1 genes, three bla_NDM-5 genes, one bla_NDM-7 gene, and six bla_IMP-4 genes. Most isolates harbored multiple drug resistance gene, especially as related to extended-spectrum-β-lactamases, bla_SHV, bla_TEM and bla_CTX-M-15 genes.The resistant gene was transferred into recipient Escherichia coli J53 through conjugation in 21.3% (10/47) of the strains. MLST revealed that ST76 (n = 36) was the most predominant clone, followed by ST896, ST323 and ST11. A new one ST 2946 was identity by this study.

Conclusion

The carbapenem resistance phenomenon is alarming and bla_KPC-2 is the main resistant gene of CNSE in our hospital. This is the first report of an outbreak caused by bla_KPC-2 positive K. pneumoniae ST76 in the Eastern region of Heilongjiang Province, China. Relevant departments should implement infection control and prevention measures to avoid further dissemination of the multi drug-resistant bacteria (MDR).

Role of association of OmpK35 and OmpK36 alteration and blaESBL and/or blaAmpC genes in conferring carbapenem resistance among non-carbapenemase-producing Klebsiella pneumoniae

In Klebsiella pneumoniae, loss of the two major outer membrane porins (OMPs) OmpK35 and OmpK36 confers resistance to carbapenems in strains producing extended-spectrum β-lactamases (ESBLs) or plasmid-mediated AmpC-type β-lactamases. This study investigated mechanisms responsible for carbapenem resistance in non-carbapenemase-producing K. pneumoniae (NCPK). All carbapenem-resistant Enterobacteriaceae (CRE) at Charles Nicolle Hospital (Tunis, Tunisia) were collected over a 6-year period (2010-2015). Among the 334 CRE strains collected, 44 (13.2%) were NCPK. MIC ranges for ertapenem, imipenem and meropenem were 1 to >32 mg/L, 0.125-8 mg/L and 0.125-32 mg/L, respectively. All strains showed a multidrug-resistant (MDR) phenotype and were negative for carbapenemase activity. None of the carbapenemase genes searched for were found. ESBL production was confirmed in all isolates except one [CTX-M-15 (n = 39) and SHV-5 (n = 4)]. Three isolates produce DHA-1 (associated with CTX-M-15 in two strains). Molecular fingerprints grouped the 44 NCPK isolates into seven clusters. In seven representative strains of these clusters, SDS-PAGE results showed that four isolates lacked the OmpK35 porin, one isolate lacked OmpK36 and two isolates lacked both OmpK35 and OmpK36. Sequencing of the corresponding porin genes showed amino acid insertions and deletions leading to early termination of translation, point mutations in the promoter region, or insertion sequences disrupting the gene coding sequence. Loss or deficiency of OMPs, coupled with ESBL and/or AmpC production, plays an important role in conferring carbapenem resistance in K. pneumoniae. Dissemination of these MDR bacteria in our hospital may create serious therapeutic problems in the future.

Antibiotic resistance ofKlebsiella pneumoniae through β-arrestin recruitment-induced β-lactamase signaling pathway

Overuse and misuse of antibiotics leads to rapid evolution of antibiotic-resistant bacteria and antibiotic resistance genes. Klebsiella pneumoniae has become the most common pathogenic bacterium accountable for nosocomial infections due to its high virulence factor and general occurrence of resistance to most antibiotics. The β-lactamase signaling pathway has been suggested to be involved in antibiotic resistance against β-lactams in Klebsiella pneumoniae. In the present study, the molecular mechanism of the antibiotic resistance of Klebsiella pneumoniae was investigated and the results indicated involvement of the β-arrestin recruitment-induced β-lactamase signaling pathway. Antimicrobial susceptibility of Klebsiella pneumoniae was assessed using automated systems and extended-spectrum β-lactamase (ESBL) and β-arrestin expression levels in Klebsiella pneumoniae were analyzed by reverse-transcription quantitative PCR. β-lactam resistance in Klebsiella pneumoniae was determined using β-lactam agar screening plates. The results demonstrated that β-arrestin recruitment was increased in Klebsiella pneumoniae with antibiotic resistance (AR-K.P.) compared with that in the native Klebsiella pneumoniae strain (NB-K.P.). Increased production of ESBL was observed in AR-K.P. after treatment with the β-lactam penicillin. Of note, inhibition of β-arrestin recruitment significantly suppressed ESBL expression in AR-K.P. and in addition, genes encoding β-arrestin and ESBL were upregulated in Klebsiella pneumoniae. Restoration of endogenous β-arrestin markedly increased antibiotic resistance of Klebsiella pneumoniae to β-lactam. Knockdown of endogenous β-arrestin downregulated antibiotic resistance genes and promoted the inhibitory effects of β-lactam antibiotic treatment on Klebsiella pneumoniae growth. In conclusion, the present study identified that β-arrestin recruitment was associated with growth and resistance to β-lactams, which suggested that β-arrestin regulating ESBL expression may be a potential target for addressing antibiotic resistance to β-lactams in Klebsiella pneumoniae.

An Outbreak of Infections Caused by a Klebsiella pneumoniae ST11 Clone Coproducing Klebsiella pneumoniae Carbapenemase-2 and RmtB in a Chinese Teaching Hospital

Background:

Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae bacteria, which cause serious disease outbreaks worldwide, was rarely detected in Xiangya Hospital, prior to an outbreak that occurred from August 4, 2014, to March 17, 2015. The aim of this study was to analyze the epidemiology and molecular characteristics of the K. pneumoniae strains isolated during the outbreak.

Methods:

Nonduplicate carbapenem-resistant K. pneumoniae isolates were screened for bla_KPC-2 and multiple other resistance determinants using polymerase chain reaction. Subsequent studies included pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, analysis of plasmids, and genetic organization of bla_KPC-2 locus.

Results:

Seventeen bla_KPC-2-positive K. pneumoniae were identified. A wide range of resistant determinants was detected. Most isolates (88.2%) coharbored bla_KPC-2 and rmtB in addition to other resistance genes, including bla_SHV-1, bla_TEM-1, and aac(3)-IIa. The bla_KPC-2 and rmtB genes were located on the conjugative IncFIB-type plasmid. Genetic organization of bla_KPC-2 locusin most strains was consistent with that of the plasmid pKP048. Four types (A1, A2, A3, and B) were detected by PFGE, and Type A1, an ST11, was the predominant PFGE type. A novel K. pneumoniae sequence type (ST1883) related to ST11 was discovered.

Conclusions:

These isolates in our study appeared to be clonal and ST11 K. pneumoniae was the predominant clone attributed to the outbreak. Coharbing of bla_KPC-2 and rmtB, which were located on a transferable plasmid, in clinical K. pneumoniae isolates may lead to the emergence of a new pattern of drug resistance.

Chromosomal Integration of the Klebsiella pneumoniae Carbapenemase Gene, blaKPC, in Klebsiella Species Is Elusive but Not Rare

Carbapenemase genes in Enterobacteriaceae are mostly described as being plasmid associated. However, the genetic context of carbapenemase genes is not always confirmed in epidemiological surveys, and the frequency of their chromosomal integration therefore is unknown. A previously sequenced collection of bla_KPC-positive Enterobacteriaceae from a single U.S. institution (2007 to 2012; n = 281 isolates from 182 patients) was analyzed to identify chromosomal insertions of Tn4401, the transposon most frequently harboring bla_KPC Using a combination of short- and long-read sequencing, we confirmed five independent chromosomal integration events from 6/182 (3%) patients, corresponding to 15/281 (5%) isolates. Three patients had isolates identified by perirectal screening, and three had infections which were all successfully treated. When a single copy of bla_KPC was in the chromosome, one or both of the phenotypic carbapenemase tests were negative. All chromosomally integrated bla_KPC genes were from Klebsiella spp., predominantly K. pneumoniae clonal group 258 (CG258), even though these represented only a small proportion of the isolates. Integration occurred via IS15-ΔI-mediated transposition of a larger, composite region encompassing Tn4401 at one locus of chromosomal integration, seen in the same strain (K. pneumoniae ST340) in two patients. In summary, we identified five independent chromosomal integrations of bla_KPC in a large outbreak, demonstrating that this is not a rare event. bla_KPC was more frequently integrated into the chromosome of epidemic CG258 K. pneumoniae lineages (ST11, ST258, and ST340) and was more difficult to detect by routine phenotypic methods in this context. The presence of chromosomally integrated bla_KPC within successful, globally disseminated K. pneumoniae strains therefore is likely underestimated.

Molecular Characteristics and Antibiotic Resistance Profiles of Klebsiella Isolates in Mthatha, Eastern Cape Province, South Africa

The increase in the incidence of extended-spectrum β-lactamase- (ESBL-) producing Klebsiella species has become a serious problem worldwide, because of their incrimination in antibiotic resistance. The objective of this study is to investigate the resistance genes responsible for ESBL-producing Klebsiella species and carbapenemase-producing Klebsiella (CRE) isolated in Mthatha and to study their epidemiology. A prospective, descriptive study of 202 nonrepetitive samples from patients was obtained from Nelson Mandela Academic Hospital. The cultured Klebsiella isolates were subjected to antimicrobial susceptibility tests and the polymerase chain reaction of bla_CTX-M, bla_TEM, bla_SHV, bla_KPC, and bla_NDM genes. Overall K. pneumoniae were the majority with 169 (83.7%) species isolates, followed by K. oxytoca with 29 (14.4%), while K. ozaenae and Raoultella ornithinolytica were 2 (0.9%) each. The prevalence of ESBL production in all Klebsiella species was 117 (57.9%). ESBL-genotypic resistance is driven in Mthatha by bla_SHV 121 (77.1%) followed by bla_TEM 105 (66.9%) and bla_CTX-M at 89 (56.7%). The most common ESBL genotype combination among the Klebsiella was bla_TEM + bla_SHV + bla_CTX-M at 79 (50.3%). There is a steady increase in the rate of ESBL genes in the last five years.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread.