Characterization of OXA-48-like carbapenemase producers in Canada, 2011-14

Characterization of ST15-KL112 Klebsiella pneumoniae Co-Harboring Bla oxa-232 and rmtF in China

Introduction

This study aimed to investigate the emergence and characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that demonstrate resistance to multiple antibiotics, including aminoglycosides and tigecycline, in a Chinese hospital.

Methods

A group of ten CRKP strains were collected from the nine patients in a Chinese hospital. Antimicrobial Susceptibility Testing (AST) and phenotypic inhibition assays precisely assess bacterial antibiotic resistance. Real-time quantitative PCR (RT-qPCR) was used to analyze the mRNA levels of efflux pump genes (acrA/acrB and oqxA/oqxB) and the regulatory gene (ramA). The core-genome tree and PFGE patterns were analyzed to assess the clonal and horizontal transfer expansion of the strains. Whole-genome sequencing was performed on a clinical isolate of K. pneumoniae named Kpn20 to identify key resistance genes and antimicrobial resistance islands (ARI).

Results

The CRKP strains showed high resistance to carbapenems, aminoglycosides (CLSI, 2024), and tigecycline (EUCAST, 2024). The mRNA expression levels of efflux pump genes and regulatory genes were detected by RT-qPCR. All 10 isolates had significant differences compared to the control group of ATCC13883. The core-genome tree and PFGE patterns revealed five clusters, indicating clonal and horizontal transfer expansion. Three key resistance genes (blaoxa-232, blaCTX-M-15 , and rmtF) were observed in the K. pneumoniae clinical isolate Kpn20. Mobile antibiotic resistance islands were identified containing bla CTX-M-15 and rmtF, with multiple insertion sequences and transposons present. The coexistence of bla oxa-232 and rmtF in a high-risk K. pneumoniae strain was reported. Conjugation assay was utilized to investigate the transferability of bla oxa-232-encoding plasmids horizontally.

Conclusion

The study highlights the emergence of ST15-KL112 high-risk CRKP strains with multidrug resistance, including to aminoglycosides and tigecycline. The presence of mobile ARI and clonal and horizontal transfer expansion of strains indicate the threat of transmission of these strains. Future research is needed to assess the prevalence of such isolates and develop effective control measures.

Escherichia coli sequence type 410 with carbapenemases: a paradigm shift within E. coli toward multidrug resistance

Escherichia coli sequence type ST410 is an emerging carbapenemase-producing multidrug-resistant (MDR) high-risk One-Health clone with the potential to significantly increase carbapenem resistance among E. coli. ST410 belongs to two clades (ST410-A and ST410-B) and three subclades (ST410-B1, ST410-B2, and ST410-B3). After a fimH switch between clades ST410-A and ST410-B1, ST410-B2 and ST410-B3 subclades showed a stepwise progression toward developing MDR. (i) ST410-B2 initially acquired fluoroquinolone resistance (via homologous recombination) in the 1980s. (ii) ST410-B2 then obtained CMY-2, CTX-M-15, and OXA-181 genes on different plasmid platforms during the 1990s. (iii) This was followed by the chromosomal integration of blaCMY-2, fstl YRIN insertion, and ompC/ompF mutations during the 2000s to create the ST410-B3 subclade. (iv) An IncF plasmid "replacement" scenario happened when ST410-B2 transformed into ST410-B3: F36:31:A4:B1 plasmids were replaced by F1:A1:B49 plasmids (both containing blaCTX-M-15) followed by blaNDM-5 incorporation during the 2010s. User-friendly cost-effective methods for the rapid identification of ST410 isolates and clades are needed because limited data are available about the frequencies and global distribution of ST410 clades. Basic mechanistic, evolutionary, surveillance, and clinical studies are urgently required to investigate the success of ST410 (including the ability to acquire successive MDR determinants). Such information will aid with management and prevention strategies to curb the spread of carbapenem-resistant E. coli. The medical community can ill afford to ignore the spread of a global E. coli clone with the potential to end the carbapenem era.

Longitudinal genomic surveillance of multidrug-resistant Escherichia coli carriage in critical care patients

Colonization with multidrug-resistant Escherichia coli strains causes a substantial health burden in hospitalized patients. We performed a longitudinal genomics study to investigate the colonization of resistant E. coli strains in critically ill patients and to identify evolutionary changes and strain replacement events within patients. Patients were admitted to the intensive care unit and hematology wards at a major hospital in Lebanon. Perianal swabs were collected from participants on admission and during hospitalization, which were screened for extended-spectrum beta-lactamases and carbapenem-resistant Enterobacterales. We performed whole-genome sequencing and analysis on E. coli strains isolated from patients at multiple time points. The E. coli isolates were genetically diverse, with 11 sequence types (STs) identified among 22 isolates sequenced. Five patients were colonized by E. coli sequence type 131 (ST131)-encoding CTX-M-27, an emerging clone not previously observed in clinical samples from Lebanon. Among the eight patients whose resident E. coli strains were tracked over time, five harbored the same E. coli strain with relatively few mutations over the 5 to 10 days of hospitalization. The other three patients were colonized by different E. coli strains over time. Our study provides evidence of strain diversity within patients during their hospitalization. While strains varied in their antimicrobial resistance profiles, the number of resistance genes did not increase over time. We also show that ST131-encoding CTX-M-27, which appears to be emerging as a globally important multidrug-resistant E. coli strain, is also prevalent among critical care patients and deserves further monitoring.IMPORTANCEUnderstanding the evolution of bacteria over time in hospitalized patients is of utmost significance in the field of infectious diseases. While numerous studies have surveyed genetic diversity and resistance mechanisms in nosocomial infections, time series of within-patient dynamics are rare, and high-income countries are over-represented, leaving low- and middle-income countries understudied. Our study aims to bridge these research gaps by conducting a longitudinal survey of critically ill patients in Lebanon. This allowed us to track Escherichia coli evolution and strain replacements within individual patients over extended periods. Through whole-genome sequencing, we found extensive strain diversity, including the first evidence of the emerging E. coli sequence type 131 clone encoding the CTX-M-27 beta-lactamase in a clinical sample from Lebanon, as well as likely strain replacement events during hospitalization.

Plasmid genomic epidemiology of blaKPC carbapenemase-producing Enterobacterales in Canada, 2010-2021

Carbapenems are considered last-resort antibiotics for the treatment of infections caused by multidrug-resistant Enterobacterales, but carbapenem resistance due to acquisition of carbapenemase genes is a growing threat that has been reported worldwide. Klebsiella pneumoniae carbapenemase (blaKPC) is the most common type of carbapenemase in Canada and elsewhere; it can hydrolyze penicillins, cephalosporins, aztreonam, and carbapenems and is frequently found on mobile plasmids in the Tn4401 transposon. This means that alongside clonal expansion, blaKPC can disseminate through plasmid- and transposon-mediated horizontal gene transfer. We applied whole genome sequencing to characterize the molecular epidemiology of 829 blaKPC carbapenemase-producing isolates collected by the Canadian Nosocomial Infection Surveillance Program from 2010 to 2021. Using a combination of short-read and long-read sequencing, we obtained 202 complete and circular blaKPC-encoding plasmids. Using MOB-suite, 10 major plasmid clusters were identified from this data set which represented 87% (175/202) of the Canadian blaKPC-encoding plasmids. We further estimated the genomic location of incomplete blaKPC-encoding contigs and predicted a plasmid cluster for 95% (603/635) of these. We identified different patterns of carbapenemase mobilization across Canada related to different plasmid clusters, including clonal transmission of IncF-type plasmids (108/829, 13%) in K. pneumoniae clonal complex 258 and novel repE(pEh60-7) plasmids (44/829, 5%) in Enterobacter hormaechei ST316, and horizontal transmission of IncL/M (142/829, 17%) and IncN-type plasmids (149/829, 18%) across multiple genera. Our findings highlight the diversity of blaKPC genomic loci and indicate that multiple, distinct plasmid clusters have contributed to blaKPC spread and persistence in Canada.

Comparative Genomic Analysis Reveals the Emergence of ST-231 and ST-395 Klebsiella pneumoniae Strains Associated with the High Transmissibility of blaKPC Plasmids

Conjugative transposons in Gram-negative bacteria have a significant role in the dissemination of antibiotic-resistance-conferring genes between bacteria. This study aims to genomically characterize plasmids and conjugative transposons carrying integrons in clinical isolates of Klebsiella pneumoniae. The genetic composition of conjugative transposons and phenotypic assessment of 50 multidrug-resistant K. pneumoniae isolates from a tertiary-care hospital (SQUH), Muscat, Oman, were investigated. Horizontal transferability was investigated by filter mating conjugation experiments. Whole-genome sequencing (WGS) was performed to determine the sequence type (ST), acquired resistome, and plasmidome of integron-carrying strains. Class 1 integrons were detected in 96% of isolates and, among integron-positive isolates, 18 stains contained variable regions. Horizontal transferability by conjugation confirmed the successful transfer of integrons between cells and WGS confirmed their presence in conjugative plasmids. Dihydrofolate reductase (dfrA14) was the most prevalent (34.8%) gene cassette in class 1 integrons. MLST analysis detected predominantly ST-231 and ST-395. BlaOXA-232 and blaCTX-M-15 were the most frequently detected carbapenemases and beta-lactamases in the sequenced isolates. This study highlighted the high transmissibility of MDR-conferring conjugative plasmids in clinical isolates of K. pneumoniae. Therefore, the wise use of antibiotics and the adherence to effective infection control measures are necessary to limit the further dissemination of multidrug-resistant bacteria.

Increased clonal dissemination of OXA-232-producing ST15 Klebsiella pneumoniae in Zhejiang, China from 2018 to 2021

BACKGROUND

OXA-232-producing Klebsiella pneumoniae was first identified in China in 2016, and its clonal transmission was reported in 2019. However, there are no prevalence and genotypic surveillance data available for OXA-232 in China. Therefore, we investigated the trends and characteristics of OXA-232 type carbapenemase in Zhejiang Province, China from 2018 to 2021.

METHODS

A total of 3278 samples from 1666 patients in the intensive care units were collected from hospitals in Zhejiang Province from 2018 to 2021. Carbapenem-resistant isolates were initially selected by China Blue agar plates supplemented with 0.3 μg/ml meropenem, and further analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry identification, immune colloidal gold technique, conjugation experiment, antimicrobial susceptibility testing and whole genome sequencing.

RESULTS

A total of 79 OXA-producing strains were recovered, with the prevalence increased from 1.8% [95% confidence interval (CI): 0.7-3.7%] in 2018 to 6.0% (95% CI: 4.4-7.9%) in 2021. Seventy-eight strains produced OXA-232 and one produced OXA-181. The bla_OXA-232 gene in all strains was located in a 6141-bp ColKP3-type non-conjugative plasmid and the bla_OXA-181 gene was located in a 51,391-bp ColKP3/IncX3-type non-conjugative plasmid. The bla_OXA-232-producing K. pneumoniae was dominated (75/76) by isolates of sequence type 15 (ST15) that differed by less than 80 SNPs. All OXA-producing strains (100%, 95% CI: 95.4-100.0%) were multidrug-resistant.

CONCLUSIONS

From 2018 to 2021, OXA-232 is the most prevalent OXA-48-like derivative in Zhejiang Province, and ST15 K. pneumoniae isolates belonging to the same clone are the major carriers. The transmission of ColKP3-type plasmid to E. coli highlighted that understanding the transmission mechanism is of great importance to delay or arrest the propagation of OXA-232 to other species.

Molecular Mechanisms Mediating Ceftazidime/Avibactam Resistance Amongst Carbapenem-Resistant Klebsiella pneumoniae Isolates from Cancer Patients

Background

A growing body of evidence suggests that ceftazidime/avibactam (CZA) is a potential therapeutic option for carbapenem-resistant Klebsiella pneumoniae (CRKP) infections; however, resistant strains are increasingly emerged worldwide. Herein, we deemed to investigate the susceptibility profile of CRKP isolates from cancer patients to CZA and to identify the underlying resistance mechanisms.

Methods

Clinical samples were obtained from adult patients admitted to the Oncology Center of Mansoura University, Mansoura, Egypt. The antibiotic susceptibility pattern of K. pneumoniae isolates to different antibiotics was tested by the modified Kirby Bauer's disc diffusion method. Minimum inhibitory concentrations of CZA were assessed using broth microdilution method. Screening for carbapenemase-producing strains was achieved by the modified Hodge test. Multiplex polymerase chain reactions (PCRs) were conducted for uncovering of carbapenemase-encoding genes (bla_KPC, bla_VIM, bla_IMP, bla_NDM-1 , and bla_OXA-48 ), and outer membrane porin genes (ompK35 and ompK36).

Results

A total of 12 CZA-resistant isolates were identified out of 47 CRKP isolates (25.5%). The MIC₅₀ and MIC₉₀ of CZA against CRKP were 1 and 64 µg/mL, respectively. Risk factors for CZA resistance included chronic kidney disease, mechanical ventilation, longer length of hospital stay, and ICU admission. The multivariate logistic regression demonstrated that longer length of hospital stay (P=0.03) was the only independent predictor for acquisition of CZA-resistant isolates. The leading mechanism for CZA resistance was sustained by bla_KPC (50%), meanwhile 16.7% and 8.3% of the CZA-resistant isolates harbored bla_OXA-48 and bla_OXA-48 /bla_NDM-1 , respectively. The MBL-encoding genes bla_NDM-1 and bla_IMP were detected in 16.7% and 8.3% of the isolates, respectively. Absence of both ompK35 and ompK36 was observed in 58.3% of the CZA-resistant isolates.

Conclusion

CZA has displayed superior in vitro activity against CRKP isolates in comparison to other antibiotics; however, thorough molecular characterization of resistant strains is highly recommended in future studies to detect and monitor the emergence of further tackling strains.

OXA-48-Like β-Lactamases: Global Epidemiology, Treatment Options, and Development Pipeline

Modern medicine is threatened by the rising tide of antimicrobial resistance, especially among Gram-negative bacteria, where resistance to β-lactams is most often mediated by β-lactamases. The penicillin and cephalosporin ascendancies were, in their turn, ended by the proliferation of TEM penicillinases and CTX-M extended-spectrum β-lactamases. These class A β-lactamases have long been considered the most important. For carbapenems, however, the threat is increasingly from the insidious rise of a class D carbapenemase, OXA-48, and its close relatives. Over the past 20 years, OXA-48 and "OXA-48-like" enzymes have proliferated to become the most prevalent enterobacterial carbapenemases across much of Europe, Northern Africa, and the Middle East. OXA-48-like enzymes are notoriously difficult to detect because they often cause only low-level in vitro resistance to carbapenems, meaning that the true burden is likely underestimated. Despite this, they are associated with carbapenem treatment failures. A highly conserved incompatibility complex IncL plasmid scaffold often carries bla_OXA-48 and may carry other antimicrobial resistance genes, leaving limited treatment options. High conjugation efficiency means that this plasmid is sometimes carried by multiple Enterobacterales in a single patient. Producers evade most β-lactam-β-lactamase inhibitor combinations, though promising agents have recently been licensed, notably ceftazidime-avibactam and cefiderocol. The molecular machinery enabling global spread, current treatment options, and the development pipeline of potential new therapies for Enterobacterales that produce OXA-48-like β-lactamases form the focus of this review.

Comparison of Two Distinct Subpopulations of Klebsiella pneumoniae ST16 Co-Occurring in a Single Patient

The higher resistance rate to ceftazidime-avibactam (CZA) is mainly related to carbapenem resistance, especially New Delhi metallo-β-lactamase (NDM). The CZA-susceptible Klebsiella pneumoniae (K191663) and the later CZA-resistant isolates (K191724, K191725, K191773) co-producing NDM-4 and OXA-181 were obtained from the same hospitalized patient returning from Vietnam. Our study aims to elucidate the diversity of K. pneumoniae ST16 through comparative analysis of whole-genome sequencing (WGS) data and identify the potential evolution of plasmids by sequencing longitudinal clinical isolates during antibiotic treatment. Firstly, multilocus sequence typing analysis and phylogenic analysis suggested that these strains belong to the two lineages of K. pneumoniae ST16. Surprisingly, the CZA-resistant strains were closely related to K. pneumoniae ST16 described in South Korea, instead of the bla_NDM-4- or bla_OXA-181-carrying ST16 reported in Vietnam. Secondly, bla_NDM-4, bla_TEM-1B, and rmtB co-existed on a self-conjugative IncFII(Yp)-like plasmid, which played a significant role in CZA resistance. It could transfer into the recipient Escherichia coli J53 at high frequency, indicating the risk of mobile carbapenemases. In addition, the loss of 12-kbp fragment occurred in bla_NDM-4-positive isolate (K191773), which was likely caused by insertion sequence-mediated homologous recombination. Last but not least, as a repressor of acrAB operon system, acrR was truncated by a frameshift mutation in K191663. Thus, our study provided baseline information for monitoring the occurrence and development of bacterial resistance.

IMPORTANCE As a leading health care-acquired infection pathogen, Klebsiella pneumoniae is threatening a large number of inpatients due to its diverse antibiotic resistance and virulence factors. Heretofore, with a growing number of reports about the coexistence of several carbapenemases in carbapenem-resistant K. pneumoniae (CRKP), epidemiologic surveillance has been strengthened. Nevertheless, the nosocomial outbreaks by CRKP ST16 are gradually increasing worldwide. Our study provides a deeper insight into the diversification of clinical isolates of CRKP ST16 in China. In addition, the comparison analysis of resistant plasmids may reveal the transmission of carbapenemase-encoding genes. Furthermore, our study also highlights the importance of longitudinal specimen collection and continuous monitoring during the treatment, which play a crucial role in understanding the development of antibiotic resistance and the evolution of resistance plasmids.

Emergence of oxacillinase-181 carbapenemase-producing diarrheagenic Escherichia coli in Ghana

The emergence and spread of carbapenemase-producing bacteria are serious threats to public health. We characterized two OXA-181-producing Escherichia coli isolates from pediatric patients with diarrhea from Ghana. bla_OXA-₁₈₁ was localized on the self-conjugative IncX3-containing plasmid in the E. coli ST410 isolate, belonging to an emerging lineage, and an IncFIC(FII)-containing plasmid in E. coli ST940. The bla_OXA-181-qnrS1 region was found on the IS26 composite transposon, which contained a 366-bp deletion in the region encoding the Rep A protein for the IncX3-containing plasmid. The IncFIC(FII) plasmid was novel and integrated with an approximately 39-kb IncX1 plasmid through conjugal transfer. Both plasmids clustered close to plasmids from Switzerland. To the best of our knowledge, this is the first report describing the presence of an IncX3 plasmid containing bla_OXA-181 in strains closely related to the B4/H24RxC clade in Africa, suggesting its emergence and the need to strengthen antimicrobial resistance surveillance.

blaOXA-48-like genome architecture among carbapenemase-producing Escherichia coli and Klebsiella pneumoniae in the Netherlands

Carbapenem-hydrolysing enzymes belonging to the OXA-48-like group are encoded by blaOXA-48-like alleles and are abundant among Enterobacterales in the Netherlands. Therefore, the objective here was to investigate the characteristics, gene content and diversity of the blaOXA-48-like carrying plasmids and chromosomes of Escherichia coli and Klebsiella pneumoniae collected in the Dutch national surveillance from 2014 to 2019 in comparison with genome sequences from 29 countries. A combination of short-read genome sequencing with long-read sequencing enabled the reconstruction of 47 and 132 complete blaOXA-48-like plasmids for E. coli and K. pneumoniae, respectively. Seven distinct plasmid groups designated as pOXA-48-1 to pOXA-48-5, pOXA-181 and pOXA-232 were identified in the Netherlands which were similar to internationally reported plasmids obtained from countries from North and South America, Europe, Asia and Oceania. The seven plasmid groups varied in size, G+C content, presence of antibiotic resistance genes, replicon family and gene content. The pOXA-48-1 to pOXA-48-5 plasmids were variable, and the pOXA-181 and pOXA-232 plasmids were conserved. The pOXA-48-1, pOXA-48-2, pOXA-48-3 and pOXA-48-5 groups contained a putative conjugation system, but this was absent in the pOXA-48-4, pOXA-181 and pOXA-232 plasmid groups. pOXA-48 plasmids contained the PemI antitoxin, while the pOXA-181 and pOXA-232 plasmids did not. Furthermore, the pOXA-181 plasmids carried a virB2-virB3-virB9-virB10-virB11 type IV secretion system, while the pOXA-48 plasmids and pOXA-232 lacked this system. A group of non-related pOXA-48 plasmids from the Netherlands contained different resistance genes, non-IncL-type replicons or no replicons. Whole genome multilocus sequence typing revealed that the blaOXA-48-like plasmids were found in a wide variety of genetic backgrounds in contrast to chromosomally encoded blaOXA-48-like alleles. Chromosomally localized blaOXA-48 and blaOXA-244 alleles were located on genetic elements of variable sizes and comprised regions of pOXA-48 plasmids. The blaOXA-48-like genetic element was flanked by a direct repeat upstream of IS1R, and was found at multiple locations in the chromosomes of E. coli. Lastly, K. pneumoniae isolates carrying blaOXA-48 or blaOXA-232 were mostly resistant for meropenem, whereas E. coli blaOXA-48, blaOXA-181 and chromosomal blaOXA-48 or blaOXA-244 isolates were mostly sensitive. In conclusion, the overall blaOXA-48-like plasmid population in the Netherlands is conserved and similar to that reported for other countries, confirming global dissemination of blaOXA-48-like plasmids. Variations in size, presence of antibiotic resistance genes and gene content impacted pOXA-48, pOXA-181 and pOXA-232 plasmid architecture.

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.

Environmental dissemination of carbapenemase-producing Enterobacteriaceae in rivers in Switzerland

The aquatic environment takes on a key role in the dissemination of antimicrobial-resistant Enterobacteriaceae. This study assesses the occurrence of carbapenemase-producing Enterobacteriaceae (CPE) in freshwater samples from rivers, inland canals, and streams throughout Switzerland, and characterizes the isolated strains using phenotypic and NGS-based genotypic methods. CPE producing KPC-2 (n = 2), KPC-3 (n = 1), NDM-5 (n = 3), OXA-48 (n = 3), OXA-181 (n = 6), and VIM-1 (n = 2) were detected in 17/164 of the water samples. Seven Escherichia coli had sequence types (STs) that belonged to extra-intestinal pathogenic clonal lineages ST38, ST73, ST167, ST410, and ST648. The majority (16/17) of the carbapenemase genes were located on plasmids, including the widespread IncC (n = 1), IncFIIA (n = 1), and IncFIIB plasmids (n = 4), the epidemic IncL (n = 1) and IncX3 (n = 5) plasmids, a rare Col156 plasmid (n = 1), and the mosaic IncFIB, IncR, and IncQ plasmids (n = 3). Plasmids were composed of elements that were identical to those of resistance plasmids retrieved from clinical and veterinary isolates locally and worldwide. Our data show environmental dissemination of high-risk CPE clones in Switzerland. Epidemic and mosaic-like plasmids carrying clinically relevant carbapenemase genes are replicating and evolving pollutants of river ecosystems, representing a threat to public health and environmental integrity.

In vitro evaluation of double carbapenem and colistin combinations against OXA-48, NDM carbapenemase-producing colistin-resistant Klebsiella pneumoniae strains

BACKGROUND

Treatment of pandrug-resistant isolates often necessitates combination therapy. Checkerboard synergy and time-killing assay tests were performed to evaluate the benefits of a triple combination with meropenem, ertapenem, and colistin against 10 colistin-resistant K. pneumoniae clinical isolates harboring different β-lactamases. (bla_OXA-48, bla_NDM).

MATERIALS AND METHODS

In this study, ertapenem and meropenem (ERT/MEM), meropenem and colistin (MEM/COL), ertapenem, meropenem and colistin (ERT/MEM/COL) combinations were tested using checkerboard techniques and time-kill assays of each antibiotic alone and in combination against 10 colistin-resistant clinical K. pneumoniae isolates. An analysis of K. pneumoniae isolate B6 using a scanning electron microscope revealed morphologic changes in the cell surface after treatment with each antibiotic both alone and in combination. The whole genome of K. pneumoniae KPNB1 was sequenced using an Ion Torrent PGM sequencer.

RESULTS

According to the checkboard results, synergistic combinations were observed with ertapenem/meropenem (5/10 isolates), meropenem/colistin (7/10) and ertapenem/meropenem/colistin (9/10); no antagonism was observed for all combinations. For the time-kill assay results; synergism and bactericidal effects were observed with meropenem/colistin (10/10) and with ertapenem/meropenem/colistin (10/10) combinations, and an indifference effect was observed with the ertapenem and meropenem (10/10) combination. Strain number 1 was found 100% identical to Klebsiella pneumoniae subsp. pneumoniae HS11286 according to the outcomes of complete genome sequence analysis, and the strain carried the genes bla_OXA-181, bla_CTXM-15, blaNDM, arr-3, aac (6')-Ib-cr, rmtF, and catB1.

CONCLUSION

Using double carbapenem antibiotics with colistin could be a potential alternative to treat colistin and carbapenem-resistant K. pneumoniae. The present study is the first Turkish report of OXA-181-type carbapenemase causing colistin resistance.

Winter is coming - Impact of temperature on the variation of beta-lactamase and mcr genes in a wastewater treatment plant

Wastewater treatment plants (WWTP) play a key role in the dissemination of antibiotic resistance and analyzing the abundance of antibiotic resistance genes (ARGs) and resistant bacteria is necessary to evaluate the risk of proliferation caused by WWTPs. Since few studies investigated the seasonal variation of antibiotic resistance, this study aimed to determine the abundance of beta-lactamase and mcr genes and to characterize phenotypic resistant strains in a WWTP in Germany over the seasons. Wastewater, sewage sludge and effluent samples were collected over a one year period and analyzed using quantitative real-time PCR. Resistant strains were isolated, followed by identification and antibiotic susceptibility testing using VITEK 2. The results show a significantly higher occurrence of nearly all investigated ARGs in the wastewater compared to sewage sludge and effluent. ARG abundance and temperature showed a negative correlation in wastewater and significant differences between ARG abundance during warmer and colder seasons were determined, indicating a seasonal effect. Co-occurrence of mcr-1 and carbapenemase genes in a multi-drug resistant Enterobacter cloacae and Escherichia coli producing extended-spectrum beta-lactamase (ESBL) was determined. To the best of our knowledge, this is the first detection of mcr-1, bla_VIM and bla_OXA-48 in an ESBL-producing E. coli. Although wastewater treatment reduced the abundance of ARGs and resistant strains, a dissemination into the river might be possible because carbapenemase-, CTX-M- and mcr-1-gene harboring strains were still present in the effluent.

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Epidemiology of carbapenemase-producing Enterobacterales in the Middle East: a systematic review

Introduction: The Middle East is actually recognized as endemic for carbapenemases-producing Enterobacterales (CPE) including at least OXA-48-like and NDM-like.Areas covered: We performed a search of PubMed and Scopus using relevant keywords. We included peer-reviewed articles published only in English reporting any data on carbapenemase-producing bacteria from Middle East countries. The last literature search was performed on 26 October 2019. All studies describing carbapenemase-producing Enterobacterales isolated from humans, animals or environmental samples from the Middle East were included.Expert opinion: The Middle-East is considered an endemic region for CPE strains and the extensive international exchange could facilitate the spread of CPE from these countries to other parts of the Globe in which the prevalence of the CPE is low. The expansion of the Middle East conflict has been associated with the rapid collapse of the existing health care system of the concerned countries. Considering that Millions of refugees have fled their country, they could introduce these CPE strains in countries with low endemicity. In conclusion, the health care system actors should take in a count the endemicity of CPE in these countries and develop local surveillance programs to limit the spread of these MDR bacteria.

The Global Ascendency of OXA-48-Type Carbapenemases

Surveillance studies have shown that OXA-48-like carbapenemases are the most common carbapenemases in Enterobacterales in certain regions of the world and are being introduced on a regular basis into regions of nonendemicity, where they are responsible for nosocomial outbreaks. OXA-48, OXA-181, OXA-232, OXA-204, OXA-162, and OXA-244, in that order, are the most common enzymes identified among the OXA-48-like carbapenemase group. OXA-48 is associated with different Tn1999 variants on IncL plasmids and is endemic in North Africa and the Middle East. OXA-162 and OXA-244 are derivatives of OXA-48 and are present in Europe. OXA-181 and OXA-232 are associated with ISEcp1, Tn2013 on ColE2, and IncX3 types of plasmids and are endemic in the Indian subcontinent (e.g., India, Bangladesh, Pakistan, and Sri Lanka) and certain sub-Saharan African countries. Overall, clonal dissemination plays a minor role in the spread of OXA-48-like carbapenemases, but certain high-risk clones (e.g., Klebsiella pneumoniae sequence type 147 [ST147], ST307, ST15, and ST14 and Escherichia coli ST38 and ST410) have been associated with the global dispersion of OXA-48, OXA-181, OXA-232, and OXA-204. Chromosomal integration of bla _OXA-48 within Tn6237 occurred among E. coli ST38 isolates, especially in the United Kingdom. The detection of Enterobacterales with OXA-48-like enzymes using phenotypic methods has improved recently but remains challenging for clinical laboratories in regions of nonendemicity. Identification of the specific type of OXA-48-like enzyme requires sequencing of the corresponding genes. Bacteria (especially K. pneumoniae and E. coli) with bla _OXA-48, bla _OXA-181, and bla _OXA-232 are emerging in different parts of the world and are most likely underreported due to problems with the laboratory detection of these enzymes. The medical community should be aware of the looming threat that is posed by bacteria with OXA-48-like carbapenemases.

Rapidly disseminating blaOXA-232 carrying Klebsiella pneumoniae belonging to ST231 in India: multiple and varied mobile genetic elements

Background

Recently, in India, there has been a shift from NDM to OXA48-like carbapenemases. OXA-181 and OXA-232 are the frequently produced variants of OXA48-like carbapenemases. OXA48-like carbapenemases are also known to be carried on transposons such as Tn1999, Tn1999.2 and it is also associated with IS1R carried on Tn1999. In India, there are no previous reports studying the association of mobile genetic elements (MGEs) with OXA48-like carbapenemases. The present study was aimed at determining the genetic backbone of OXA48-like carbapenemases to determine the role of MGEs in its transfer and to investigate the Inc plasmid type carrying bla_OXA48-like.

Results

A total of 49 carbapenem resistant K. pneumoniae which included 25 isolates from South India and 24 isolates from North India, were included in the study. Whole genome sequencing using Ion Torrent PGM was performed to study the isolates. OXA-232 was present in 35 isolates (71%). In 19 isolates (39%), bla_OXA48-like was associated with MGEs. Insertion sequences such as ISX4, IS1, IS3, ISKpn1, ISKpn26, ISKpn25, ISSpu2, ISKox1, IS4321R, ISEc36, and ISPa38; and transposons such as TnAs3 and Tn2, were present. Isolates from northern and southern India belonging to same sequence type (ST) had diverse genetic backbone for bla_OXA48-like. ST14 isolates from north had IS5 and Tn3 families while from south they had IS1, IS5 and IS630 families. ST231 from north had IS5, IS6 and Tn3 families with bla_OXA-232 while from south, IS1, IS3 and IS5 families were observed; with ISKpn26 being present among isolates from both the regions. bla_OXA48-like was predominantly found on ColKP3 plasmid. ST231 was the predominant ST in 22 isolates (45%).

Conclusion

OXA-232 is the predominant variant of OXA48-like carbapenemase with ST231 being the commonest ST of OXA48-like carbapenemase producing K. pneumoniae in India. Diverse MGEs have been associated with both bla_OXA-232 and bla_OXA-181 which contribute to their spread. The MGEs in the present study are different from those reported earlier. There is no clonal expansion of bla_OXA48-like producing K. pneumoniae since diverse STs were observed. Monitoring the genetic backbone of OXA48-like carbapenemase is essential to better understand the transmission dynamics of XDR K. pneumoniae.

Epidemic IncX3 plasmids spreading carbapenemase genes in the United Arab Emirates and worldwide

Purpose

Plasmids of the incompatibility group X type 3 (IncX3) were described carrying various carbapenemase genes in carbapenemase-producing Enterobacteriaceae (CPE) worldwide and in the United Arab Emirates (UAE), as well. To understand the driving force behind the emergence of such plasmids in the UAE, the relationship between IncX3 plasmids encountered locally and globally was investigated.

Methods

CPE strains isolated in the UAE during 2009-2014 were screened by X3 PCR-based replicon typing. The clonal relationship of CPE carrying IncX3 plasmids was determined by multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Complete sequence of selected IncX3 plasmids was determined. Phylogenetic relationship between the carbapenemase carrying IncX3 plasmids from the UAE and of those reported worldwide was established by comparing the plasmid backbones.

Results

10.2% of the 295 CPE tested were identified to carry IncX3 plasmids: 13 Escherichia coli, 13 Klebsiella pneumoniae, two Enterobacter cloacae, one Citrobacter freundii and one Morganella morganii isolate, respectively. Most of them were non-clonal; with small clusters of triplets and pairs of E. coli and K. pneumoniae, and a cluster of five K. pneumoniae ST11 exhibiting >90% similar PFGE patterns, respectively. The 30 isolates harbored either bla _NDM-1, bla _NDM-4, bla _NDM-5, bla _NDM-7, bla _OXA-181 or bla _KPC-2 carbapenemase genes on IncX3 plasmids. Phylogenetic analysis of the backbone region of IncX3 plasmids carrying various beta-lactamase genes from the UAE (n=23) and that of North-America, Europe, Asia and Australia (n=35) revealed three clusters based on the carbapenemase genes carried: plasmids harboring bla _OXA-181 and bla _NDM-5 formed two distinct groups, whereas backbones of plasmids with bla _NDM-1, bla _NDM-4 and bla _NDM-7 clustered together. Each cluster contained plasmids of diverse geographical origin.

Conclusion

The findings suggest that different carbapenemase gene carrying IncX3 plasmids encountered in the UAE do not evolve locally, rather are subtypes of this epidemic plasmid emerging in this country due to international transfer.

Screening and Characterization of Multidrug-Resistant Gram-Negative Bacteria from a Remote African Area, São Tomé and Príncipe

The occurrence of resistance to last-resort antibiotics was evaluated among Enterobacteriaceae isolates recovered from hospitalized children in a remote African archipelago, São Tomé and Príncipe, where there is limited access to those antibiotics. Fifty patients were screened for colonization by carbapenem-, pan-aminoglycoside-, or polymyxin-resistant Enterobacteriaceae A total of 36 isolates (including 30 Escherichia coli and 4 Klebsiella pneumoniae) were recovered from 23 patients, including 26 isolates harboring the bla_OXA-181 carbapenemase gene, a single isolate harboring the 16S rRNA methylase gene rmtB encoding pan-resistance to aminoglycosides, and 8 isolates coharboring both genes. A single isolate possessed the plasmid-borne colistin resistance gene mcr-1 A high clonal relationship was found for OXA-181-producing E. coli (4 clones), and conversely, three of the four OXA-181-producing K. pneumoniae isolates were clonally unrelated. This study overall showed a high prevalence of resistance to last-resort antibiotics in this country, where no epidemiological data were previously available.

Early emergence of OXA-181-producing Escherichia coli ST410 in China

OBJECTIVES

The aim of this study was to investigate the prevalence and characterisation of OXA-48-like-producing Enterobacteriaceae in Henan Province, China.

METHODS

A total of 339 carbapenem-non-susceptible clinical Enterobacteriaceae isolates [imipenem or meropenem minimum inhibitory concentration (MIC) of >1μg/mL] obtained between January 2013 and December 2016 were screened for the presence of the bla_OXA-48-like gene by PCR and sequencing. Antimicrobial susceptibility to various antimicrobials agents was examined by MIC testing. Multilocus sequence typing (MLST) was performed for bacterial genotyping. The plasmid pEC21-OXA-181 was transformed into Escherichia coli DH5α by electroporation and was sequenced using an Illumina MiSeq platform, followed by subsequent annotation and genetic analysis.

RESULTS

Among the 339 carbapenem-non-susceptible Enterobacteriaceae isolates, only one (0.3%) E. coli strain EC21, belonging to ST410, was positive for bla_OXA-181, a variant of bla_OXA-48. This OXA-181-producing E. coli, recovered from a patient without a history of foreign travel, was obtained earlier than the first reported bla_OXA-181-positive E. coli (WCHEC14828) in Sichuan Province, China. Plasmid analysis revealed that bla_OXA-181 together with the quinolone resistance gene qnrS1 was carried by an IS26-flanked composite transposon on a 51-kb IncX3-type plasmid.

CONCLUSIONS

These findings indicate the emergence of OXA-181-producing E. coli in China earlier than previously thought. The bla_OXA-181 gene is associated with the widely disseminated potentially endemic E. coli ST410 clone and is carried by an IncX3 plasmid, a common vehicle for spreading NDM-type carbapenemases, which might promote the further dissemination of bla_OXA-181 among the Enterobacteriaceae in China.

Extended-spectrum β-lactamase-producing and carbapenemase-producing Enterobacteriaceae

Antimicrobial resistance (AMR) is a global public-health emergency, which threatens the advances made by modern medical care over the past century. The World Health Organization has recently published a global priority list of antibiotic-resistant bacteria, which includes extended-spectrum β-lactamase-producing Enterobacteriaceae and carbapenemase-producing Enterobacteriaceae. In this review, we highlight the mechanisms of resistance and the genomic epidemiology of these organisms, and the impact of AMR.