Emergence of Plasmid-Mediated Fosfomycin-Resistance Genes among Escherichia coli Isolates, France

Structural Studies of Klebsiella pneumoniae Fosfomycin-Resistance Protein and Its Application for the Development of an Optical Biosensor for Fosfomycin Determination

Fosfomycin-resistance proteins (FosAs) are dimeric metal-dependent glutathione transferases that conjugate the antibiotic fosfomycin (Fos) to the tripeptide glutathione (γ-Glu-Cys-Gly, GSH), rendering it inactive. In the present study, we reported a comparative analysis of the functional features of two FosAs from Pseudomonas aeruginosa (FosAPA) and Klebsiella pneumoniae (FosAKP). The coding sequences of the enzymes were cloned into a T7 expression vector, and soluble active enzymes were expressed in E. coli. FosAKP displayed higher activity and was selected for further studies. The crystal structure of the dimeric FosAKP was determined via X-ray crystallography at 1.48 Å resolution. Fos and tartrate (Tar) were found bound in the active site of the first and second molecules of the dimer, respectively. The binding of Tar to the active site caused slight rearrangements in the structure and dynamics of the enzyme, acting as a weak inhibitor of Fos binding. Differential scanning fluorimetry (DSF) was used to measure the thermal stability of FosAKP under different conditions, allowing for the selection of a suitable buffer to maximize enzyme operational stability. FosAKP displays absolute specificity towards Fos; therefore, this enzyme was exploited for the development of an enzyme-based colorimetric biosensor. FosAKP was tethered at the bottom of a plastic cuvette using glutaraldehyde chemistry to develop a simple colorimetric method for the determination of Fos in drinking water and animal plasma.

Synergistic Antimicrobial Activity of Eugenol in Combination with Fosfomycin to Combat Escherichia coli and Potential Effect on Plasmid-Mediated Fosfomycin Resistance Genes

The presence of multidrug-resistant pathogenic microorganisms makes it challenging to cure bacterial illnesses. Syzygium aromaticum has been used for medicinal purposes since ancient times. The objective of this study was to investigate the potential synergistic effect of the combination of Eugenol and Fosfomycin against clinically Uropathogenic Escherichia coli (UPEC) and their possible co-treatment as well as their contribution to plasmid-mediated Fosfomycin resistance (fosA3 and fosA4) genes using molecular assays. Eugenol was extracted from clove (Syzygium aromaticum) plants using steam distillation by Clevenger and analyzed by high-performance liquid chromatography (HPLC). UPEC accounted for 63.6 % of all isolates. Specifically, 99.3 % of the UPEC isolates exhibited resistance to multiple types of antibiotics [multidrug-resistant (MDR)]. The MIC for Eugenol was 1.25-5 μg/mL, and Fosfomycin was 512-1024 μg/mL, while the MBC for Eugenol was 5-10 μg/mL and Fosfomycin was 2048 μg/mL. The synergistic effects were considerable, with 1/4 MIC of Eugenol resulting in 1/8 MIC Fosfomycin. Eugenol inhibited most of the UPEC isolates at 4-8 hours, Fosfomycin at 8-12 hours, and co-treatment at 4-8 hours. The fosA3 and fosA4 genes were detected in 5.7 % and 2.9 % of the isolates, respectively. The results showed variable gene expression changes in response to the different treatments.

Occurrence of plasmid-mediated fosfomycin resistance (fos genes) among Escherichia coli isolates, Portugal

OBJECTIVES

To evaluate the occurrence of plasmid-mediated fos genes among fosfomycin-resistant Escherichia coli isolates collected from patients in Lisbon, Portugal, and characterize the fos-positive strains.

METHODS

A total of 19 186 E. coli isolates were prospectively collected between April 2022 and January 2023 from inpatients and outpatients at a private laboratory in Lisbon. Fosfomycin resistance was initially assessed by semi-automated systems and further confirmed by the disc diffusion method. Resistant isolates were investigated for plasmid-mediated fos genes (fosA1-fosA10, fosC and fosL1-fosL2) and extended-spectrum beta-lactamases (ESBLs) by PCR and sequencing. Multilocus sequence typing was performed to evaluate the clonal relationship among fos-carrying isolates.

RESULTS

Out of the 19 186 E. coli isolates, 100 were fosfomycin-resistant (0.5%), out of which 15 carried a fosA-like gene (15%). The most prevalent fosfomycin-resistant determinant was fosA3 (n = 11), followed by fosA4 (n = 4). Among the 15 FosA-producing isolates, 10 co-produced an ESBL (67%), being either of CTX-M-15 (n = 8) or CTX-M-14 (n = 2) types. The fosA3 gene was carried on IncFIIA-, IncFIB-, and IncY-type plasmids, whereas fosA4 was always located on IncFIB-type plasmids. Most FosA4-producing isolates belonged to a single sequence type ST2161, whereas isolates carrying the fosA3 gene were distributed into nine distinct genetic backgrounds.

CONCLUSION

The prevalence of fosfomycin-resistant E. coli isolates is still low in Portugal. Notably, 15% of fosfomycin-resistant isolates harbour a transferable fosA gene, among which there is a high rate of ESBL producers, turning traditional empirical therapeutical options used in Portugal (fosfomycin and amoxicillin-clavulanic acid) ineffective.

Plasmid-mediated fosfomycin resistance in Escherichia coli isolates of worldwide origin

OBJECTIVES

Fosfomycin is a first-line treatment for uncomplicated urinary tract infections (UTIs) in several European countries, and it is increasingly becoming the treatment of choice globally. Resistance to fosfomycin in Escherichia coli can be exerted through several mechanisms, including the acquisition of fosfomycin-modifying enzymes, of which the FosA-type enzymes are the most common. This study analysed, both phenotypically and genotypically, an international collection of E. coli strains harbouring acquired fosA genes.

METHODS

Thirty-one fosA-positive E. coli isolates were obtained from both clinical and environmental sources, from seven countries (Portugal (n = 12), Switzerland (n = 9), China (n = 3), France (n = 2), Nepal (n = 2), South Africa (n = 2), Kuwait (n = 1)). MICs were determined according to EUCAST guidelines. Whole genome sequencing (WGS) was performed on 23 isolates, and complete fosA plasmid sequences were determined for 12. Conjugation assays were performed on seven isolates.

RESULTS

All isolates exhibited high-level resistance to fosfomycin (64 to >256 mg/L). WGS of 23 isolates identified 17 sequence types (STs), and 16 harboured fosA3, four fosA4, two fosA8, and one fosA10. ESBLs, pAmpC, or carbapenemase genes were present in 15, four, and three isolates, respectively. The fosA plasmids of 12 isolates were determined and were diverse in size (∼67 kb to ∼235 kb), resistance gene carriage, and replicon types. Six fosA plasmids additionally carried ESBL or carbapenemase genes. Conjugation assays, performed on seven isolates harbouring diverse plasmids, identified that all were capable of being transmitted.

CONCLUSION

This study highlights the necessity of the surveillance and close monitoring of fosfomycin resistance in E. coli, essential to maintain the optimal use of this treatment option.

High incidence of fosfomycin-resistant uropathogenic E. coli among children

BACKGROUND

There are few epidemiological or molecular data on Escherichia coli (E. coli) strains resistant to fosfomycin. In this study, we described the occurrence and characterization of fosfomycin-resistant uropathogenic E. coli (UPEC) isolated from children.

MATERIALS AND METHODS

This study was carried out on 96 E. coli isolates obtained from children with urinary tract infections. Two methods were performed to detect fosfomycin resistance: The agar dilution method and the rapid fosfomycin test. The disc diffusion method was done to detect the antimicrobial susceptibility pattern of all isolates. The phylogenetic grouping of all isolates was done according to the modified Clermont method. Conventional PCR was performed to detect plasmid-mediated fosfomycin-resistant genes (fos genes) and the bla_CTX-M gene.

RESULTS

Analyses of data were performed by SPSS software. A high percentage of fosfomycin resistance (37/96; 38.5%) was reported among UPEC isolates. The fosfomycin-resistant strains showed a higher resistance rate than fosfomycin-susceptible isolates to different antibiotics. E group (62.2%) was the most predominant phylogenetic group among the fosfomycin-resistant UPEC isolates, followed by Group B2 (21.6%) and group D (13.5%). The fos genes were detected in 21 isolates with the fosA3 gene as the most frequent, which was detected in 11 isolates followed by fosA (8), fosC2 (4), fosA4(1), and fosA5(1) genes.

CONCLUSION

This is the first report of a high prevalence of plasmid-mediated fosfomycin-resistant UPEC in Egypt. All of these isolates were multidrug-resistant to the tested antibiotics. Close monitoring of such strains is mandatory to prevent widespread dissemination of the genes code for antibiotic resistance.

Fosfomycin resistance mechanisms in Enterobacterales: an increasing threat

Antimicrobial resistance is well-known to be a global health and development threat. Due to the decrease of effective antimicrobials, re-evaluation in clinical practice of old antibiotics, as fosfomycin (FOS), have been necessary. FOS is a phosphonic acid derivate that regained interest in clinical practice for the treatment of complicated infection by multi-drug resistant (MDR) bacteria. Globally, FOS resistant Gram-negative pathogens are raising, affecting the public health, and compromising the use of the antibiotic. In particular, the increased prevalence of FOS resistance (FOS^R) profiles among Enterobacterales family is concerning. Decrease in FOS effectiveness can be caused by i) alteration of FOS influx inside bacterial cell or ii) acquiring antimicrobial resistance genes. In this review, we investigate the main components implicated in FOS flow and report specific mutations that affect FOS influx inside bacterial cell and, thus, its effectiveness. FosA enzymes were identified in 1980 from Serratia marcescens but only in recent years the scientific community has started studying their spread. We summarize the global epidemiology of FosA/C2/L1-2 enzymes among Enterobacterales family. To date, 11 different variants of FosA have been reported globally. Among acquired mechanisms, FosA3 is the most spread variant in Enterobacterales, followed by FosA7 and FosA5. Based on recently published studies, we clarify and represent the molecular and genetic composition of fosA/C2 genes enviroment, analyzing the mechanisms by which such genes are slowly transmitting in emerging and high-risk clones, such as E. coli ST69 and ST131, and K. pneumoniae ST11. FOS is indicated as first line option against uncomplicated urinary tract infections and shows remarkable qualities in combination with other antibiotics. A rapid and accurate identification of FOS^R type in Enterobacterales is difficult to achieve due to the lack of commercial phenotypic susceptibility tests and of rapid systems for MIC detection.

Polyclonal Spread of Fosfomycin Resistance among Carbapenemase-Producing Members of the Enterobacterales in the Czech Republic

Fosfomycin (FOS) has been recently reintroduced into clinical practice, but its effectiveness against multidrug-resistant (MDR) Enterobacterales is reduced due to the emergence of FOS resistance. The copresence of carbapenemases and FOS resistance could drastically limit antibiotic treatment. The aims of this study were (i) to investigate fosfomycin susceptibility profiles among carbapenem-resistant Enterobacterales (CRE) in the Czech Republic, (ii) to characterize the genetic environment of fosA genes among the collection, and (iii) to evaluate the presence of amino acid mutations in proteins involved in FOS resistance mechanisms. During the period from December 2018 to February 2022, 293 CRE isolates were collected from different hospitals in the Czech Republic. FOS MICs were assessed by the agar dilution method (ADM), FosA and FosC2 production was detected by the sodium phosphonoformate (PPF) test, and the presence of fosA-like genes was confirmed by PCR. Whole-genome sequencing was conducted with an Illumina NovaSeq 6000 system on selected strains, and the effect of point mutations in the FOS pathway was predicted using PROVEAN. Of these strains, 29% showed low susceptibility to fosfomycin (MIC, ≥16 μg/mL) by ADM. An NDM-producing Escherichia coli sequence type 648 (ST648) strain harbored a fosA10 gene on an IncK plasmid, while a VIM-producing Citrobacter freundii ST673 strain harbored a new fosA7 variant, designated fosA7.9. Analysis of mutations in the FOS pathway revealed several deleterious mutations occurring in GlpT, UhpT, UhpC, CyaA, and GlpR. Results regarding single substitutions in amino acid sequences highlighted a relationship between ST and specific mutations and an enhanced predisposition for certain STs to develop resistance. This study highlights the occurrence of several FOS resistance mechanisms in different clones spreading in the Czech Republic. IMPORTANCE Antimicrobial resistance (AMR) currently represents a concern for human health, and the reintroduction of antibiotics such as fosfomycin into clinical practice can provide further option in treatment of multidrug-resistant (MDR) bacterial infections. However, there is a global increase of fosfomycin-resistant bacteria, reducing its effectiveness. Considering this increase, it is crucial to monitor the spread of fosfomycin resistance in MDR bacteria in clinical settings and to investigate the resistance mechanism at the molecular level. Our study reports a large variety of fosfomycin resistance mechanisms among carbapenemase-producing Enterobacterales (CRE) in the Czech Republic. Our study summarizes the main achievements of our research on the use of molecular technologies, such as next-generation sequencing (NGS), to describe the heterogeneous mechanisms that reduce fosfomycin effectiveness in CRE. The results suggest that a program for widespread monitoring of fosfomycin resistance and epidemiology fosfomycin-resistant organisms can aide timely implementation of countermeasures to maintain the effectiveness of fosfomycin.

A multicentre, retrospective audit of fosfomycin use for urinary tract infections in Australian children and adolescents

BACKGROUND

Urinary tract infections (UTIs) due to MDR organisms are increasingly common. The lack of paediatric data on efficacious antibiotics makes UTI treatment particularly challenging. Data on the efficacy of fosfomycin use for UTI in children are variable.

METHODS

We conducted a retrospective audit of children aged 0-18 years who were treated with fosfomycin for UTI at seven tertiary paediatric hospitals in Australia over a 7 year period, from 2014 to 2020.

RESULTS

Ninety-one children with a median age of 5 years (range 2 months to 18 years) received oral fosfomycin for UTI. The majority (57/91, 63%) had one or more comorbidity, with the most common being renal tract anomalies (24/91, 26%). Fifty-nine (65%) had febrile UTI, 14/91 (15%) had pyelonephritis and 1/91 (1%) was bacteraemic. A majority (80/91, 88%) of urinary cultures had an ESBL-producing Gram-negative pathogen isolated. Fosfomycin susceptibility was evident in all 80 isolates tested. For uncomplicated UTI, the most common dose in children aged <1, 1-12 and >12 years was 1, 2 and 3 g, respectively. For complicated UTI, doses of 2 and 3 g were most common. The median duration of fosfomycin administration was 5 days (range 1-82). Clinical cure was achieved in 84/90 (93%); the six with treatment failure had underlying comorbidities. Overall, 2/91 (2%) children experienced drug-related adverse effects comprising gastrointestinal symptoms in both, which resolved after treatment discontinuation.

CONCLUSIONS

Fosfomycin is well tolerated and associated with favourable treatment outcomes in children with UTI. Further research on the optimal dosing strategy is required.

Models for Gut-Mediated Horizontal Gene Transfer by Bacterial Plasmid Conjugation

The emergence of new antimicrobial resistant and virulent bacterial strains may pose a threat to human and animal health. Bacterial plasmid conjugation is a significant contributor to rapid microbial evolutions that results in the emergence and spread of antimicrobial resistance (AR). The gut of animals is believed to be a potent reservoir for the spread of AR and virulence genes through the horizontal exchange of mobile genetic elements such as plasmids. The study of the plasmid transfer process in the complex gut environment is limited due to the confounding factors that affect colonization, persistence, and plasmid conjugation. Furthermore, study of plasmid transfer in the gut of humans is limited to observational studies, leading to the need to identify alternate models that provide insight into the factors regulating conjugation in the gut. This review discusses key studies on the current models for in silico, in vitro, and in vivo modeling of bacterial conjugation, and their ability to reflect the gut of animals. We particularly emphasize the use of computational and in vitro models that may approximate aspects of the gut, as well as animal models that represent in vivo conditions to a greater extent. Directions on future research studies in the field are provided.

Different fosA genes were found on mobile genetic elements in Escherichia coli from wastewaters of hospitals and municipals in Turkey

AIMS

The increasing number of globally established fosfomycin-resistant (Fos^R) Gram-negative bacteria inspired us to investigate the occurrence of Fos^REnterobacterales populations (esp. E. coli) in samples of city wastewater treatment plants (WWTPs) and hospital sewage in Hatay, Turkey. Fos^R target bacteria were further characterized for their clonal relatedness, resistomes and mobile genetic elements (MGEs) to evaluate their impact on fosfomycin resistance dissemination.

METHODS

A total of 44 samples from raw and treated waters of WWTPs as well as of two hospitals in the Hatay province were subjected to selective cultivation for recovering Fos^REnterobacterales. The presence of fosA was verified by PCR and Sanger amplicon sequencing. Detected E. coli were further evaluated against antimicrobial susceptibility-testing, macrorestriction profiling (PFGE) and whole-genome sequencing (WGS). Bioinformatics analysis was performed for genome subtyping (i.e., MLST, serotype), resistome/virulome determination and dissection of the genetic determinants of plasmidic fosA3/4 resistances.

RESULTS

Besides ten non-E. coli Enterobacterales, 29 E. coli were collected within this study. In silico-based subtyping revealed that E. coli isolates were assigned to six different serovars and 14 sequence types (ST), while O8:H21 and ST410 represented the major prevalent types, respectively. Fosfomycin resistance in the isolates was found to be mediated by the fosA4 (n = 18), fosA3 (n = 10) and fosA (n = 1), which are frequently associated with transmissible MGEs. Reconstruction of plasmid-associated fosA gene context revealed a linkage between the resistance cassette and IS6 (IS26 family) transposases, which might represent a major driver for the distribution of the genes and the generation of novel fosA-carrying plasmids.

CONCLUSIONS

The occurrence of plasmid-mediated, transmissible Fos^R in E. coli from wastewater pose a foreseeable threat to "One-Health". To minimize further spread of the resistances in bacterial populations associated with environmental, animal and human health further resistance monitoring and management strategies must be developed.

Global Threat of Carbapenem-Resistant Gram-Negative Bacteria

Infections caused by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacteria (GNB), including carbapenem-resistant (CR) Enterobacterales (CRE; harboring mainly bla_KPC, bla_NDM, and bla_OXA-48-like genes), CR- or MDR/XDR-Pseudomonas aeruginosa (production of VIM, IMP, or NDM carbapenemases combined with porin alteration), and Acinetobacter baumannii complex (producing mainly OXA-23, OXA-58-like carbapenemases), have gradually worsened and become a major challenge to public health because of limited antibiotic choice and high case-fatality rates. Diverse MDR/XDR-GNB isolates have been predominantly cultured from inpatients and hospital equipment/settings, but CRE has also been identified in community settings and long-term care facilities. Several CRE outbreaks cost hospitals and healthcare institutions huge economic burdens for disinfection and containment of their disseminations. Parenteral polymyxin B/E has been observed to have a poor pharmacokinetic profile for the treatment of CR- and XDR-GNB. It has been determined that tigecycline is suitable for the treatment of bloodstream infections owing to GNB, with a minimum inhibitory concentration of ≤ 0.5 mg/L. Ceftazidime-avibactam is a last-resort antibiotic against GNB of Ambler class A/C/D enzyme-producers and a majority of CR-P. aeruginosa isolates. Furthermore, ceftolozane-tazobactam is shown to exhibit excellent in vitro activity against CR- and XDR-P. aeruginosa isolates. Several pharmaceuticals have devoted to exploring novel antibiotics to combat these troublesome XDR-GNBs. Nevertheless, only few antibiotics are shown to be effective in vitro against CR/XDR-A. baumannii complex isolates. In this era of antibiotic pipelines, strict implementation of antibiotic stewardship is as important as in-time isolation cohorts in limiting the spread of CR/XDR-GNB and alleviating the worsening trends of resistance.

Occurrence and molecular epidemiology of fosA3-bearing Escherichia coli from ducks in Shandong province of China

The plasmid-borne fosfomycin resistance gene fosA3 has been identified in Escherichia coli (E. coli) from various animals but has rarely been reported in ducks. In this study, we investigated the fosA3 prevalence and molecular characteristics of fosA3-harboring E. coli strains from ducks in Shandong province of China. In 416 E. coli isolates, 91 (21.88%) were identified as fosA3-bearing strains, and the fosfomycin-resistant phenotype of 88 of the 91 fosA3-harboring strains was successfully transferred to the recipient strains. Seven different genetic structures surrounding the fosA3 gene were detected and 2 new contexts were discovered among the fosA3-carrying E. coli. Twenty fosA3-harboring isolates and their trans-conjugants were randomly selected for pulsed-field gel electrophoresis (PFGE) typing and S1-nuclease PFGE, respectively. The PFGE patterns revealed that the 20 randomly selected fosA3-bearing isolates were not a result of clonal dissemination. S1-PFGE showed that 15 of the 20 randomly selected trans-conjugants carried a single plasmid, and these 15 plasmids that harbored fosA3 (55-190 kb) were distributed into the following replicon types: IncF (n = 11), IncI1 (n = 1), IncN (n = 1), untypable (n = 1), and W-FIC (n = 1). Additionally, as vectors for fosA3 in E. coli, F-:A1:B6, N/ST1, IncI1/ST2, W-FIC, and one untypable plasmid had never been reported before. These observations highlighted the importance of ducks as a reservoir for multidrug-resistant fosA3-carrying E. coli.

Genetic Characterization of Multidrug-Resistant E. coli Isolates from Bloodstream Infections in Lithuania

Extraintestinal pathogenic Escherichia coli (ExPEC) isolates are a main cause of bloodstream infections. The aim of this study was to characterize 256 β-lactam–resistant, bacteremia-causing E. coli isolates collected from 12 healthcare institutions in Lithuania in 2014 and 2018. All isolates were identified as E. coli via MALDI-TOF MS and VITEK ®2. In addition, the isolates were analyzed for the presence of 29 resistance genes and 13 virulence genes, divided into phylogenetic groups (A, B1, B2, C, D, E, and F), and characterized using rep-PCR genotyping methods (BOX-PCR and (GTG)5-PCR). Analyzing the results of this study showed tetA-strB-sul2-TEM-NDM-strA-fosA-AIM-sul3-aadA-CTX-M-9 to be the most common resistance gene combination (67.2% of all isolates). Additionally, the most common virulence genes established were fimH (98.4% of all isolates), fyuA (91.8%), and traT (81.3%) and the most common gene combination was fuyA-fimH-iroN (58.6% of all isolates). Next, the isolates were separated into four phylogenetic groups: A, B1, B2, and F, where group A isolates were detected at a significantly higher frequency (79.3% of all isolates). Finally, a total of 235 genotyping profiles were established using rep-PCR methods, and all profiles were separated into fourteen genotypic clusters, with each cluster containing profiles with a variety of virulence and resistance genes not restricted to any specific cluster. The results of this study elucidate E. coli antimicrobial resistance patterns by highlighting the variability and diversity of resistance and virulence genes and providing phylogenetic classification, genetic profiling, and clustering data. These results may improve clinical control of multidrug-resistant infections in healthcare institutions and contribute to the prevention of potential outbreaks.

Selective screening culture medium for fosfomycin resistance in Enterobacterales

A selective medium for screening fosfomycin (FOS)-resistant Enterobacterales was developed. Performances of this medium were first evaluated by using cultures of a collection of 84 enterobacterial clinical strains (42 FOS-susceptible and 42 FOS-resistant). The SuperFOS medium showed excellent sensitivity and specificity of detection (100%) in those conditions. Then, by testing spiked stool and spiked urine specimens, it revealed excellent performances, with lower limits of identification ranging from 10¹ to 10² CFU/ml. This screening medium allows easy and accurate detection of FOS-resistant isolates regardless of their resistance mechanisms.

Emergence of Multidrug-Resistant Escherichia coli Producing CTX-M, MCR-1, and FosA in Retail Food From Egypt

In this study, multidrug-resistant (MDR) Escherichia coli isolates from retail food and humans assigned into similar Multilocus Sequence Types (MLST) were analyzed using whole genome sequencing (WGS). In silico analysis of assembled sequences revealed the existence of multiple resistance genes among the examined E. coli isolates. Of the six CTX-M-producing isolates from retail food, bla _CTX-M-14 was the prevalent variant identified (83.3%, 5/6). Two plasmid-mediated fosfomycin resistance genes, fosA3, and fosA4, were detected from retail food isolates (one each from chicken and beef), where fosA4 was identified in the chicken isolate 82CH that also carried the colistin resistance gene mcr-1. The bla _CTX-M-14 and fosA genes in retail food isolates were located adjacent to insertion sequences ISEcp1 and IS26, respectively. Sequence analysis of the reconstructed mcr-1 plasmid (p82CH) showed 96-97% identity to mcr-1-carrying IncI2 plasmids previously identified in human and food E. coli isolates from Egypt. Hierarchical clustering of core genome MLST (HierCC) revealed clustering of chicken isolate 82CH, co-harboring mcr-1 and fosA4 genes, with a chicken E. coli isolate from China at the HC200 level (≤200 core genome allelic differences). As E. coli co-harboring mcr-1 and fosA4 genes has only been recently reported, this study shows rapid spread of this genotype that shares similar genetic structures with regional and international E. coli lineages originating from both humans and food animals. Adopting WGS-based surveillance system is warranted to facilitate monitoring the international spread of MDR pathogens.

A Point Prevalence Survey of Antibiotic Resistance in the Irish Environment, 2018-2019

Water bodies worldwide have proven to be vast reservoirs of clinically significant antibiotic resistant organisms. Contamination of waters by anthropogenic discharges is a significant contributor to the widespread dissemination of antibiotic resistance. The aim of this research was to investigate multiple different anthropogenic sources on a national scale for the role they play in the environmental propagation of antibiotic resistance. A total of 39 water and 25 sewage samples were collected across four local authority areas in the West, East and South of Ireland. In total, 211 Enterobacterales were isolated (139 water, 72 sewage) and characterised. A subset of isolates (n=60) were chosen for whole genome sequencing. Direct comparisons of the water versus sewage isolate collections revealed a higher percentage of sewage isolates displayed resistance to cefoxitin (46%) and ertapenem (32%), while a higher percentage of water isolates displayed resistance to tetracycline (55%) and ciprofloxacin (71%). Half of all isolates displayed extended spectrum beta-lactamase (ESBL) production phenotypically (n = 105/211; 50%), with bla_CTX-M detected in 99/105 isolates by PCR. Carbapenemase genes were identified in 11 isolates (6 sewage, 5 water). The most common variant was bla_OXA-48 (n=6), followed by bla_NDM-5 (n=2) and bla_KPC-2 (n=2). Whole genome sequencing analysis revealed numerous different sequence types in circulation in both waters and sewage including E. coli ST131 (n=15), ST38 (n=8), ST10 (n=4) along with Klebsiella ST405 (n=3) and ST11 (n=2). Core genome MLST (cgMLST) comparisons uncovered three highly similar Klebsiella isolates originating from hospital sewage and two nearby waters. The Klebsiella isolates from an estuary and seawater displayed 99.1% and 98.8% cgMLST identity to the hospital sewage isolate respectively. In addition, three pairs of E. coli isolates from different waters also revealed cgMLST similarities, indicating widespread dissemination and persistence of certain strains in the aquatic environment. These findings highlight the need for routine monitoring of water bodies used for recreational and drinking purposes for the presence of multi-drug resistant organisms.

A Study on Multidrug-Resistant Escherichia coli Clinical Isolates from Different Hospitals in Greater Cairo

The biological fitness cost of antibiotic resistance is a key parameter in determining the rate of appearance and spread of antibiotic-resistant bacteria in Egypt. Our study aimed to investigate the prevalence of antibiotic resistance among Escherichia coli clinical isolates from Greater Cairo area hospitals. A total of 537 clinical isolates were recovered from samples of urine, diarrheal specimen, pus, wound culture, gastric wound, blood, drain culture, sputum, high vaginal swab, abscess, amniotic fluid, ventilator, burn swab, splenic drain culture, and unknown site of infection during different seasons. All isolates were subjected to phenotypic and genotypic susceptibility testing for colistin, nitrofurantoin, fosfomycin, and trimethoprim, quinolones, and β-lactam resistance. Our results revealed that 42.7% of the isolates harbored at least one resistance encoding gene, 10% harboring 2, 0.6% harboring 3, and 0.85% harboring 4 resistance-encoding genes. PCR reported the prevalence of resistance genes as follows: bla-SHV 13.4%, mcr-1 0.6%, qnr-A 23.8%, fos-A 1.06%, nfs-A 3.6%, and dfr-A 25.5%. We reported that three isolates carried the mcr-1 gene encoding colistin resistance from three different hospitals. Upon performing sequencing and phylogenetic analysis on the three positive mcr-1 isolates (MT890587, MT890588, and MT890589), the three isolates showed 100% identity with themselves, with some strains from Egypt and Japan, and 99.9% identity with an isolate from China.

Prevalence, detection and characterisation of fosfomycin-resistant Escherichia coli strains carrying fosA genes in Community of Madrid, Spain

OBJECTIVES

The aim of this this study was to describe the presence of different variants of the fosA gene in fosfomycin-resistant Escherichia coli strains in Madrid, Spain.

METHODS

fos genes were searched for in 55 E. coli strains collected from seven representative hospitals located in Madrid. A phenotypic screening test was performed following the disk diffusion method with sodium phosphonoformate added as described by Nakamura et al. Additionally, a molecular study based on PCR was used to confirm the screening results. Positive strains for fos genes were further subjected to whole-genome sequencing (WGS).

RESULTS

Phenotypic screening was positive in 9/55 strains (16.4%), although genotypic detection was positive in only 3 (fosA3, fosA4 and fosA6). Thus, the prevalence of fos genes in Madrid was 5.5% (3/55). WGS data were not available for the fosA6-positive strain. One isolate with fosA3 (ST69) carried a bla_CTX-M-55 gene and seven virulence genes (air, eilA, iha, iss, lpfA, sat and senB). The fosA4-positive isolate (ST4038) carried the virulence genes iss, lpfA, iroN and mchF. Both fos genes were located between two IS26 mobile elements of a plasmid.

CONCLUSION

We detected the presence of different variants of plasmid-mediated fosA genes in fosfomycin-resistant E. coli strains in Madrid, Spain. Despite the few reports in Europe, it would be of interest to monitor the spread of these acquired resistance genes.

Complete sequences of two new KPC-harbouring plasmids in Klebsiella pneumoniae ST11 strains in China

OBJECTIVES

Klebsiella pneumoniae carbapenemase (KPC) has spread across the world. The present study focused on exploring the sequences of two new KPC-harbouring plasmids in K. pneumoniae.

METHODS

Eighteen KPC-harbouring K. pneumoniae isolates were collected from a tertiary teaching hospital in 2014 in Fujian, China, among which two new KPC-harbouring plasmids (pF77 and pF5) we identified. The characteristics of the plasmids and the isolates carrying them were investigated in detail.

RESULTS

The two KPC-harbouring plasmids (pF5 and pF77) carried the antimicrobial resistance genes bla_KPC-2, bla_CTX-M-65, bla_SHV-12, catA2 and fosA3. Detailed sequence comparison revealed that the two plasmids might have evolved from recombination of the previously reported plasmids pKP1034 and pCT-KPC, which were considered to evolve from ancestor plasmids pHN7A8, pKPC-LK30 and pKPHS2. Plasmids pF5 and pF77 were non-conjugative and were mainly identified in sequence type 11 (ST11) K. pneumoniae isolates. Additionally, 4-55 core single nucleotide polymorphisms (SNPs) were identified in each pair of sequenced isolates that carried the identified plasmids.

CONCLUSION

Plasmids pF5 and pF77 as well as the previously reported plasmids pKP1034 and pCT-KPC were all detected in 2013-2014 in South China and were carried by ST11 K. pneumoniae isolates. SNP analysis indicated high similarity of the sequenced isolates. Therefore, spread of the group of plasmids may be due to an outbreak of clonal dissemination of ST11 KPC-producing K. pneumoniae. This study also highlights the importance of plasmid analysis in the surveillance and control of antibiotic resistance spread in clinical isolates.

Mobile fosfomycin resistance genes in Enterobacteriaceae-An increasing threat

Antimicrobial resistance is one of the major threats to the health and welfare of both humans and animals. The shortage of new antimicrobial agents has led to the re-evaluation of old antibiotics such as fosfomycin as a potential regimen for treating multidrug-resistant bacteria especially extended-spectrum-beta-lactamase- and carbapenemase-producing Enterobacteriaceae. Fosfomycin is a broad-spectrum bactericidal antibiotic that inhibits the initial step of the cell wall biosynthesis. Fosfomycin resistance can occur due to mutation in the drug uptake system or by the acquisition of fosfomycin-modifying enzymes. In this review, we focus on mobile fosfomycin-resistant genes encoding glutathione-S-transferase which are mainly responsible for fosfomycin resistance in Enterobacteriaceae, that is, fosA and its subtypes, fosC2, and the recently described fosL1-L2. We summarized the proposed origins of the different resistance determinants and highlighted the different plasmid types which are attributed to the dissemination of fosfomycin-modifying enzymes. Thereby, IncF and IncN plasmids play a predominant role. The detection of mobile fosfomycin-resistant genes in Enterobacteriaceae has increased in recent years. Similar to the situation in (East) Asia, the most frequently detected fosfomycin-resistant gene in Europe is fosA3. Mobile fosfomycin-resistant genes have been detected in isolates of human, animal, food, and environmental origin which leads to a growing concern regarding the risk of spread of such bacteria, especially Escherichia coli and Salmonella, at the human-animal-environment interface.

Characterization of Fosfomycin and Nitrofurantoin Resistance Mechanisms in Escherichia coli Isolated in Clinical Urine Samples

Fosfomycin and nitrofurantoin are antibiotics of choice to orally treat non-complicated urinary tract infections (UTIs) of community origin because they remain active against bacteria resistant to other antibiotics. However, epidemiologic surveillance studies have detected a reduced susceptibility to these drugs. The objective of this study was to determine possible mechanisms of resistance to these antibiotics in clinical isolates of fosfomycin- and/or nitrofurantoin-resistant UTI-producing Escherichia coli. We amplified and sequenced murA, glpT, uhpT, uhpA, ptsI, cyaA, nfsA, nfsB, and ribE genes, and screened plasmid-borne fosfomycin-resistance genes fosA3, fosA4, fosA5, fosA6, and fosC2 and nitrofurantoin-resistance genes oqxA and oqxB by polymerase chain reaction. Among 29 isolates studied, 22 were resistant to fosfomycin due to deletion of uhpT and/or uhpA genes, and 2 also possessed the fosA3 gene. Some modifications detected in sequences of NfsA (His11Tyr, Ser33Arg, Gln67Leu, Cys80Arg, Gly126Arg, Gly154Glu, Arg203Cys), NfsB (Gln44His, Phe84Ser, Arg107Cys, Gly192Ser, Arg207His), and RibE (Pro55His), and the production of truncated NfsA (Gln67 and Gln147) and NfsB (Glu54), were associated with nitrofurantoin resistance in 15/29 isolates; however, the presence of oqxAB plasmid genes was not detected in any isolate. Resistance to fosfomycin was associated with the absence of transporter UhpT expression and/or the presence of antibiotic-modifying enzymes encoded by fosA3 plasmid-mediated gene. Resistance to nitrofurantoin was associated with modifications of NfsA, NfsB, and RibE proteins. The emergence and spread of these resistance mechanisms, including transferable resistance, could compromise the future usefulness of fosfomycin and nitrofurantoin against UTIs. Furthermore, knowledge of the genetic mechanisms underlying resistance may lead to rapid DNA-based testing for resistance.

Multiple Plasmid Vectors Mediate the Spread of fosA3 in Extended-Spectrum-β-Lactamase-Producing Enterobacterales Isolates from Retail Vegetables in China

The plasmid-mediated fosfomycin resistance gene fosA3 has been detected in Enterobacterales from various sources but has rarely been reported in vegetables. In this study, the aim was to investigate the prevalence of and, subsequently, to characterize fosA3-positive Enterobacterales isolates from retail vegetables. Seventeen (7.3%) fosA3-carrying strains were identified from 233 extended-spectrum-β-lactamase-producing Enterobacterales isolates from vegetables. All 17 isolates, including six Escherichia coli, seven Klebsiella pneumoniae, two Raoultella ornithinolytica, and two Citrobacter freundii isolates, carried bla _CTX-M S1-nuclease pulsed-field gel electrophoresis (S1-PFGE) and hybridization confirmed that the fosA3 genes in 16 isolates were located on plasmids ranging in size from ∼40 kb to ∼250 kb, except one located on chromosome of C. freundii All the fosA3-carrying plasmids from 16 fosA3-positive isolates were successfully transferred into the recipient bacteria by transformation or conjugation. In agreement with data determined with isolates from food animals, the IncHI2/ST3 and IncN-F33:A-:B-/F33:A-:B plasmids were the main vectors of fosA3 in E. coli Additionally, F24:A-:B1, IncFII_K-IncR, IncFII_S, IncR, and two untypeable plasmids were found for the first time to be vectors for fosA3 in Enterobacterales The genetic contexts of fosA3 in 15 Enterobacterales isolates differed due to insertion and/or loss of molecular modules mediated by mobile elements. However, all fosA3 genes were flanked by IS26, as commonly observed in other fosA3-carrying plasmids. Here, we report a high rate of detection of fosA3 genes, mediated by multiple plasmid vectors, in ESBL-producing Enterobacterales from retail vegetables. FosA3-producing Enterobacterales could be transmitted to the human body by direct contact or consumption of vegetables, which might pose a potential threat to public health.IMPORTANCE This report provides important information on the transmission and epidemiology of fosA3 among Enterobacterales isolates from vegetables. The rate of occurrence of fosA3 in ESBL-producing Enterobacterales from retail vegetables is high, and fosA3 was found to be carried by diverse plasmids. Some novel genetic contexts of fosA3 and novel fosA3-carrying plasmids, including several plasmid types common in K. pneumoniae, were identified, increasing the number of known transfer vectors for the fosA3 gene and reflecting the complexity of fosA3 transmission in Enterobacterales The capture of fosA3 by the resident plasmid of K. pneumoniae will accelerate the spread of fosA3 in K. pneumoniae, one of the most pathogenic species in clinical medicine. Considering the clinical importance of fosfomycin, and the fact that vegetables are directly consumed, the fosfomycin resistance genes present a risk of transmission to the human body through the food chain and thus pose a threat to public health.

Synergistic activity of fosfomycin-meropenem and fosfomycin-colistin against carbapenem resistant Klebsiella pneumoniae: an in vitro evidence

Aim:

To evaluate the antibacterial activity of fosfomycin–meropenem and fosfomycin–colistin combinations against carbapenem-resistant Klebsiella pneumoniae (CR-Kp).

Methods:

A total of 50 CR-Kp isolates recovered from blood cultures were included in this study. All the CR-Kp isolates were screened for the presence of carbapenem resistant genes bla_IMP. bla_VIM. bla_NDM. bla_OXA-48 like, bla_KPC. bla_GES.#x00A0;and bla_SPM. Combination testing of fosfomycin–meropenem and fosfomycin–colistin were performed using time-kill assay.

Results:

Fosfomycin–meropenem combination showed synergy in 20% of the tested CR-Kp isolates. While, fosfomycin–colistin exhibited synergy against 16% of the isolates. A total of 68% (n = 34) of CR-Kp isolates were characterised as OXA-48-like producers and 22% (n = 11) as NDM producers. Synergistic activity of these combinations was observed against OXA-48, NDM and NDM + OXA-48 co-producers.

Conclusion:

Considerable synergistic antibacterial activity of fosfomycin–meropenem and fosfomycin–colistin was not observed against CR-Kp isolates. Therefore, these combinations may not be promising for infections associated with CR-Kp.

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) infections are difficult to treat and are associated with a high mortality rate. This study aimed to evaluate the synergistic activity of fosfomycin–meropenem and fosfomycin–colistin combinations against CR-Kp. Synergistic activity of these combinations was observed against OXA-48, NDM and NDM + OXA-48 co-producers. However, synergism was not found to be significant. Therefore, these combinations may not be promising for infections associated with CR-Kp.

Diverse and Flexible Transmission of fosA3 Associated with Heterogeneous Multidrug Resistance Regions in Salmonella enterica Serovar Typhimurium and Indiana Isolates

We identified fosA3 at a rate of 2.6% in 310 Salmonella isolates from food animals in Guangdong province, China. The fosA3 gene was genetically linked to diverse antibiotic resistance genes (ARGs), including mcr-1, bla _CTX-M-14/55, oqxAB, and rmtB These gene combinations were embedded in heterogeneous fosA3-containing multidrug resistance regions on the transferable ST3-IncHI2 and F33:A-:B- plasmids and the chromosome. This indicated a great flexibility of fosA3 cotransmission with multiple important ARGs among Salmonella species.

Identification of FosA8, a Plasmid-Encoded Fosfomycin Resistance Determinant from Escherichia coli, and Its Origin in Leclercia adecarboxylata

A plasmid-located fosfomycin resistance gene, fosA8, was identified from a CTX-M-15-producing Escherichia coli isolate recovered from urine. Identification of this gene was obtained by whole-genome sequencing. It encoded FosA8, which shares 79% and 78% amino acid identity with the most closely related FosA2 and FosA1 enzymes, respectively. The fosA8 gene was located on a transferable 50-kb plasmid of IncN type encoding high-level resistance to fosfomycin. In silico analysis and cloning experiments identified fosA8 analogues (99% identity) in the genome of Leclercia decarboxylata, which is an enterobacterial species with natural resistance to fosfomycin. This finding adds L. decarboxylata to the list of enterobacterial species that are a reservoir of fosA-like genes which have been captured from the chromosome of a progenitor and are then acquired by E. coli.

New perspectives for reassessing fosfomycin: applicability in current clinical practice

Fosfomycin is a bactericidal antibiotic that interferes with cell wall synthesis. The drug therefore has a broad spectrum of activity against a wide range of Gram-positive and Gram-negative bacteria. Both the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) have started review processes of the accumulated information on the use of fosfomycin and on information from new clinical trials. The intent is to establish usage terms in Europe and to authorize the sale of fosfomycin in the US. This monograph reviews the most current aspects of the compound. From the microbiological point of view, fosfomycin's single mechanism of action can provide a synergistic effect to other classes of antibiotics, including β-lactams, aminoglycosides, lipopeptides and fluoroquinolones. The resistance mechanisms include the reduced intracellular transport of the antibiotic, the change in target and the direct inactivation of the antibiotic by metalloenzymes and kinases; however, the clinical impact of some of these mechanisms has not yet been elucidated. The lack of agreement in determining the sensitivity cutoffs between the Clinical and Laboratory Standards Institute (CLSI) (≤64 mg/L) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) (≤32 mg/L), the fact that a number of microorganisms require a higher MIC (Klebsiella spp., Enterobacter spp., Serratia spp., Pseudomonas aeruginosa) and the drug's different effective concentrations against Gram-positive and Gram-negative bacteria have resulted in recommended dosages for treating multiresistant microorganism infections that vary between 8 and 12 g/day for Gram-positive bacteria and 16 and 24 g/day for Gram-negative bacteria. Fosfomycin has 3 presentations (intravenous with disodium salt, oral with calcium salt and combined with tromethamine),has good distribution in tissues and abscesses and is well tolerated. The pharmacodynamic ratio of dosage production for fosfomycin is AUC/MIC. However, the pharmacokinetics/pharmacodynamic ratio could be optimized in daily practice based on the pathogen, the patient's clinical profile or the infection model. Fosfomycin is the treatment of choice for cystitis in immunocompetent patients, patients with transplants, pregnant women and in pediatric settings. The drug is especially useful due to its microbiological activity and oral posology in cystitis caused by ESBL bacteria. Administer intravenously at high doses and combined with other antimicrobial agents. Fosfomycin has been useful in treating infections by multiresistant Gram-negative bacteria, such as Enterobacteriaceae, carbapenemase carriers and P. aeruginosa, extensively resistant or panresistant in urinary infections and in skin and soft tissue. Fosfomycin has also been shown active in combination with daptomycin or imipenem in osteoarticular infections by methicillin-resistant Staphylococcus aureus. Fosfomycin is an old antibiotic that still has much to reveal.

New microbiological aspects of fosfomycin

The discovery of fosfomycin more than 40 years ago was an important milestone in antibiotic therapy. The antibiotic's usefulness, alone or in combination, for treating infections caused by multidrug-resistant microorganisms is clearer than ever. Both the European Medicines Agency and the US Food and Drug Administration have open processes for reviewing the accumulated information on the use of fosfomycin and the information from new clinical trials on this compound. The agencies' objectives are to establish common usage criteria for Europe and authorize the sale of fosfomycin in the US, respectively. Fosfomycin's single mechanism of action results in no cross-resistance with other antibiotics. However, various fosfomycin-resistance mechanisms have been described, the most important of which, from the epidemiological standpoint, is enzymatic inactivation, which is essentially associated with a gene carrying a fosA3-harboring plasmid. Fosfomycin has been found more frequently in Asia in extended-spectrum beta-lactamase-producing and carbapenemase-producing Enterobacterales. Although fosfomycin presents lower intrinsic activity against Pseudomonas aeruginosa compared with that presented against Escherichia coli, fosfomycin's activity has been demonstrated in biofilms, especially in combination with aminoglycosides. The current positioning of fosfomycin in the therapeutic arsenal for the treatment of infections caused by multidrug-resistant microorganisms requires new efforts to deepen our understanding of this compound, including those related to the laboratory methods employed in the antimicrobial susceptibility testing study.

Prevalence of fosfomycin resistance among ESBL-producing Escherichia coli isolates in the community, Switzerland

Our aim was to evaluate the prevalence of fosfomycin-resistant strains among ESBL-producing Escherichia coli isolates recovered from community patients in Switzerland. A total of 1225 ESBL-producing E. coli isolates were collected between 2012 and 2013 from a private and community laboratory. Fosfomycin resistance was assessed by using the novel rapid fosfomycin/E. coli NP test and agar dilution method. Resistant isolates were further investigated for acquired resistance genes fosA1-7 by PCR and sequencing. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed to evaluate the clonal relationship among fosA3-carrying isolates. Out of the 1225 ESBL-producing E. coli isolates analyzed in this study, 1208 were fosfomycin susceptible while 17 were fosfomycin resistant. No discrepancy was observed between the rapid fosfomycin/E. coli NP test and the agar dilution method taken as the gold standard. Five out of the 17 resistant isolates carried a fosA-like gene. No clonal relationship was observed among those isolates. Here, the prevalence of fosfomycin resistance among ESBL-producing E. coli isolates in the community is reported for the first time in Switzerland, being ca. 1.4%. Among the five isolates carrying a fosA gene, four encoded the FosA3 enzyme, being the most prevalent fosfomycin-resistant determinant. An excellent correlation was observed between minimum inhibitory concentration-based susceptibility categorization and results of the rapid fosfomycin/E. coli NP test, further indicating the excellent sensitivity and specificity of this recently developed rapid test whose results are obtained in less than 2 h.

Rapid Detection of Fosfomycin Resistance in Escherichia coli

The rapid fosfomycin/Escherichia coli NP test was developed to detect fosfomycin resistance in E. coli isolates. The test is based on glucose metabolization and the detection of bacterial growth in the presence of fosfomycin at 40 µg/ml. Bacterial growth is visually detectable by an orange-to-yellow color change of red phenol, a pH indicator. A total of 100 E. coli isolates, among which 22 were fosfomycin resistant, were used to evaluate the test performance. The sensitivity and specificity of the test were 100% and 98.7%, respectively. This new test is user friendly, sensitive and specific, and its results are obtained in 1 h 30 min.

Genome Sequencing of Extended-Spectrum β-Lactamase (ESBL)-Producing Klebsiella pneumoniae Isolated from Pigs and Abattoir Workers in Cameroon

Background and objectives: Extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae is a serious public health issue globally. In this study, the antibiotic resistance genes, virulence factors, mobile genetic elements, and genetic lineages of circulating ESBL-producing K. pneumoniae strains isolated from pigs and humans in Cameroonian abattoirs were investigated using whole genome sequencing (WGS), in order to ascertain zoonotic transmission (viz. from animals to humans and/or vice-versa) in the food chain.

Methods: During March–October 2016, 288 nasal and rectal pooled samples from 432 pigs as well as nasal and hand swabs from 82 humans were collected from Cameroon and South Africa. Seven ESBL-producing K. pneumoniae circulating in Cameroonian pig abattoirs were selected and their genomic DNA sequenced using an Illumina MiSeq platform. Generated reads were de novo assembled using the Qiagen CLC Genomics Workbench and SPAdes. The assembled contigs were annotated using RAST and antibiotic resistance genes, virulence factors, plasmids, and bacteriophages were identified with ResFinder, Virulence Finder, PlasmidFinder, and PHAST, respectively.

Results: ESBL-producing K. pneumoniae were detected in pigs (34/158; 21.52%) and exposed workers (8/71; 11.26%) in Cameroon only. The circulating K. pneumoniae strains were dominated principally by the sequence type (ST) 14 and 39. In addition, the “high-risk” ST307 clone and two novel STs assigned ST2958 and ST2959 were detected. Genomic analysis identified various antibiotic resistance genes associated with resistance to β-lactams, aminoglycosides, fluoroquinolones, macrolide, lincosamide and streptogramins, rifampicin, sulfonamides, trimethoprim, phenicols and tetracycline. None of the ESBL-producing K. pneumoniae harbored virulence genes. Intermingled K. pneumoniae populations were observed between pig- and human-source within and across abattoirs in the country.

Conclusion: Our study shows that ESBL-producing K. pneumoniae is actively disseminating in pigs and occupationally exposed workers in Cameroonian pig abattoirs and is probably underestimated in the absence of molecular epidemiological studies. It suggests pigs, abattoir workers and food products as potential reservoirs and sources of zoonotic transmission in Cameroon. Our findings underline the existence of a potential unheeded food safety and public health threat associated with these resistant strains and reinforce the crucial importance of implementing appropriate food safety measures and promoting rational antibiotic use.