https://doi.org/10.1016/j.wroa.2023.100174

Uncovering the diverse hosts of tigecycline resistance gene tet(X4) in anaerobic digestion systems treating swine manure by epicPCR

With the large-scale use of antibiotics, antibiotic resistant bacteria (ARB) continue to rise, and antibiotic resistance genes (ARGs) are regarded as emerging environmental pollutants. The new tetracycline-class antibiotic, tigecycline is the last resort for treating multidrug-resistant (MDR) bacteria. Plasmid-mediated horizontal transfer enables the sharing of genetic information among different bacteria. The tigecycline resistance gene tet(X) threatens the efficacy of tigecycline, and the adjacent ISCR2 or IS26 are often detected upstream and downstream of the tet(X) gene, which may play a crucial driving role in the transmission of the tet(X) gene. Since the first discovery of the plasmid-mediated high-level tigecycline resistance gene tet(X4) in China in 2019, the tet(X) genes, especially tet(X4), have been reported within various reservoirs worldwide, such as ducks, geese, migratory birds, chickens, pigs, cattle, aquatic animals, agricultural field, meat, and humans. Further, our current researches also mentioned viruses as novel environmental reservoirs of antibiotic resistance, which will probably become a focus of studying the transmission of ARGs. Overall, this article mainly aims to discuss the current status of plasmid-mediated transmission of different tet(X) genes, in particular tet(X4), as environmental pollutants, which will risk to public health for the "One Health" concept. 

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Dissemination and prevalence of plasmid-mediated high-level tigecycline resistance gene tet (X4)

Salmonella Typhimurium is associated with foodborne diseases worldwide, including in Peru, and its emerging antibiotic resistance (AMR) is now a global public health problem. Therefore, country-specific monitoring of the AMR emergence is vital to control this pathogen, and in these aspects, whole genome sequence (WGS)—based approaches are better than gene-based analyses. Here, we performed the antimicrobial susceptibility test for ten widely used antibiotics and WGS-based various analyses of 90 S. Typhimurium isolates (human, animal, and environment) from 14 cities of Peru isolated from 2000 to 2017 to understand the lineage and antimicrobial resistance pattern of this pathogen in Peru. Our results suggest that the Peruvian isolates are of Typhimurium serovar and predominantly belong to sequence type ST19. Genomic diversity analyses indicate an open pan-genome, and at least ten lineages are circulating in Peru. A total of 48.8% and 31.0% of isolates are phenotypically and genotypically resistant to at least one antibiotic, while 12.0% are multi-drug resistant (MDR). Genotype–phenotype correlations for ten tested drugs show >80% accuracy, and >90% specificity. Sensitivity above 90% was only achieved for ciprofloxacin and ceftazidime. Two lineages exhibit the majority of the MDR isolates. A total of 63 different AMR genes are detected, of which 30 are found in 17 different plasmids. Transmissible plasmids such as lncI-gamma/k, IncI1-I(Alpha), Col(pHAD28), IncFIB, IncHI2, and lncI2 that carry AMR genes associated with third-generation antibiotics are also identified. Finally, three new non-synonymous single nucleotide variations (SNVs) for nalidixic acid and eight new SNVs for nitrofurantoin resistance are predicted using genome-wide association studies, comparative genomics, and functional annotation. Our analysis provides for the first time the WGS-based details of the circulating S. Typhimurium lineages and their antimicrobial resistance pattern in Peru.

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WGS-Based Lineage and Antimicrobial Resistance Pattern of Salmonella Typhimurium Isolated during 2000–2017 in Peru

The emergence of hypervirulent Klebsiella pneumoniae (hvKp) poses a great threat to human health, while tigecycline provides an important guarantee for the treatment of MDR-hvKp infections. Currently, prevalence of tet(X4)-positive hvKp in animal origin remains unknown. Six tet(X4)-positive K. pneumoniae isolates were isolated from pork samples in China. Notably, one of them was identified as a hvKp isolate. This isolate has a hypermucoviscous and a hypervirulent phenotype according to string test and mouse infection model. The tet(X4) gene in six K. pneumoniae isolates was located on an IncFII(pCRY) plasmid. Interestingly, the backbone structure of IncFII(pCRY) tet(X4)-positive plasmid was similar to that of blaKPC-2-positive plasmid in hvKp. Besides, this IncFII(pCRY) plasmid can be transferred into E. coli and ST11 hvKp, and does not incur a significant fitness cost, and is able to persist stably. A novel tet(X4) core genetic environment (abh-tet(X4)-IS102-1-ISCR2) was found on the plasmid. To the best of our knowledge, this is the first report of tet(X4)-positive hvKp in animals. Our findings highlight the urgent need for further global surveillance of tet(X4)-positive hvKp in clinical and animal farming settings with the One Health approach. 

Emergence of tet(X4)-positive hypervirulent Klebsiella pneumoniae of food origin in China

A set of antibiotic-resistance mechanisms and virulence factors in GES-16-producing Klebsiella quasipneumoniae subsp. Similipneumoniae from hospital wastewater revealed by whole-genome sequencing.

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

Emergence of pathogens harboring tigecycline resistance genes incurs great concerns. Wastewater is recognized as the important reservoir of antimicrobial resistance genes. Here we characterized the phenotypes and genotypes of bacteria carrying tet(X4) from wastewater in Turkey for the first time. Four tet(X4)-positive Escherichia coli isolates were identified and characterized by PCR, Sanger sequencing, antimicrobial susceptibility testing, conjugation assays, Illumina sequencing, nanopore sequencing and bioinformatic analysis. Four tet(X4)-harboring isolates were multidrug-resistant (MDR) bacteria and the tet(X4) gene was nontransferable in four isolates. Genetic analysis revealed that tet(X4) genes in four isolates were located on plasmids co-harboring two replicons IncFIA(HI1) and IncFIB(K). However, none of the four plasmids carried genes associated with horizontal transfer of plasmids. The coexistence of blaSHV-12-bearing IncX3-type plasmid and tet(X4)-harboring plasmid was also found in one isolate. These findings indicate that continuous surveillance of the tet(X4)-bearing isolates in different environments worldwide should be strengthened. ABSTRACT Emergence of pathogens harboring tigecycline resistance genes incurs great concerns. Wastewater is recognized as the important reservoir of antimicrobial resistance genes. Here we characterized the phenotypes and genotypes of bacteria carrying tet(X4) from wastewater in Turkey for the first time. Four tet(X4)-positive Escherichia coli isolates were identified and characterized by PCR, Sanger sequencing, antimicrobial susceptibility testing, conjugation assays, Illumina sequencing, nanopore sequencing and bioinformatic analysis. Four tet(X4)-harboring isolates were multidrug-resistant (MDR) bacteria and the tet(X4) gene was nontransferable in four isolates. Genetic analysis revealed that tet(X4) genes in four isolates were located on plasmids co-harboring two replicons IncFIA(HI1) and IncFIB(K). However, none of the four plasmids carried genes associated with horizontal transfer of plasmids. The coexistence of blaSHV-12-bearing IncX3-type plasmid and tet(X4)-harboring plasmid was also found in one isolate. These findings indicate that continuous surveillance of the tet(X4)-bearing isolates in different environments worldwide should be strengthened. IMPORTANCE The emergence of tigecycline resistance genes in humans and animals in China seriously threatens the clinical utility of tigecycline, but the molecular epidemiology of tigecycline-resistant bacteria in other countries remained largely unknown. Therefore, it is necessary to learn the prevalence and molecular characteristics of bacteria carrying tigecycline resistance genes, particularly the mobilizable tet(X4), in other countries. In the study, we first described the presence and molecular characteristics of the tet(X4)-positive E. coli isolates from wastewater in Turkey. Four tet(X4)-bearing isolates belonged to ST609, an E. coli clone commonly found from humans, animals and the environment. These findings highlight the importance of monitoring the tet(X4) gene in different settings globally.

Emergence and Characterization of Tigecycline Resistance Gene tet(X4) in ST609 Escherichia coli Isolates from Wastewater in Turkey

Disinfectant and heavy metal resistance profiles in extended spectrum β-lactamase (ESBL) producing Escherichia coli isolates from chicken meat samples.

Design and modification of frog skin peptide brevinin-1GHa with enhanced antimicrobial activity on Gram-positive bacterial strains

In this study, antimicrobial nanofibers were produced with the mixtures of polyvinyl alcohol (PVA) and cyclotide-rich fractions by electrospinning method. After extraction, the first separation was carried out with C18 flash chromatography and then fractioned into five separate parts by reversed-phase high-pressure liquid chromatography (RP-HPLC). The molecular weights of cyclotides in each fraction were determined by quadrupole time-of-flight liquid chromatography-mass spectrometry (Q-TOF LC-MS). Cyclotide-rich fractions were mixed with 10% of PVA solution and nanofibers were produced from this biocomposite mixture by electrospinning method. The nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), and it was observed that 100% peptide-containing nanofibers (cyclotide-rich fraction/10% PVA, w/v) had more regular fiber textures. The presence of the peptides in the nanofiber was also confirmed by analytical RP-HPLC, as the peptides in both peptide fractions and nanofiber solutions have the same retention times. The nanofibers produced with the fourth cyclotide-rich fraction showed activity against gram-positive bacteria (Bacillus cereus) in antimicrobial susceptibility test. As a result of these findings, cyclotide-containing nanofibers with antimicrobial activity can be produced for pharmaceutical research and development studies. 

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Cemil Kürekci

Papers

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

Emergence and Characterization of Tigecycline Resistance Gene tet(X4) in ST609 Escherichia coli Isolates from Wastewater in Turkey

Disinfectant and heavy metal resistance profiles in extended spectrum β-lactamase (ESBL) producing Escherichia coli isolates from chicken meat samples.

Design and modification of frog skin peptide brevinin-1GHa with enhanced antimicrobial activity on Gram-positive bacterial strains

Cyclotide-rich fractions containing nanofibers by electrospinning: preparation, characterization and examination of antimicrobial activity