The study reports the development of an efficient multiplex PCR method to detect the expanding family of tet(X) variants, including tet(X1) to tet(X5), which are responsible for tigecycline resistance in various bacterial species.

The study identifies that azidothymidine enhances the effectiveness of tigecycline against tigecycline-resistant E. coli by inhibiting the enzymatic activity of Tet(X3/X4) and disrupting DNA synthesis.

The study developed a TaqMan-based multiplex real-time PCR assay for the rapid detection of tigecycline resistance genes tet(X3) and tet(X4) in various samples, demonstrating high specificity and sensitivity.

The study identified the tet(X4) gene as a plasmid-encoded tigecycline resistance gene prevalent in Escherichia coli isolates from pigs and chickens in northwestern China, highlighting its potential for human transmission.

The study identifies tet(X2) as the predominant tigecycline resistance gene in Flavobacteriaceae, with tet(X3), tet(X4), and tet(X5) also found in various bacterial species. The research suggests Flavobacteriaceae as a potential ancestral source of the tet(X) gene.

The study developed a MALDI-TOF MS-based assay to rapidly detect Tet(X)-producing E. coli and Acinetobacter spp. by identifying a unique peak of an oxygen-modified derivative of tigecycline. The assay showed high sensitivity (99.19%) and specificity (100%).

Four tet(X) variants (tet(X3), tet(X4), tet(X5.2), and tet(X5.3)) were identified in Acinetobacter species, showing high-level resistance to tigecycline, tetracycline, eravacycline, and omadacycline. These genes were found in multiple Acinetobacter species and were associated with IS CR2 elements, facilitating their spread.

The report highlights the prevalence of antimicrobial resistance in zoonotic and indicator bacteria, including high resistance levels to ampicillin, tetracyclines, and fluoroquinolones in Salmonella and Campylobacter isolates. It also notes the emergence of resistance to third-generation cephalosporins and carbapenems, along with the detection of linezolid-resistant strains harboring the cfr gene in fattening pigs.

The study identified multiple antimicrobial resistance genes in Salmonella enterica isolates from retail meat in Beijing, including beta-lactamases (blaCTX-M-55, blaCTX-M-14, blaCTX-M-65), aminoglycoside resistance genes (aac(6')-Iaa, aph(6)-Id, aph(3")-Ib), sulfonamide resistance gene (sul2), beta-lactamase (blaTEM-1B), quinolone resistance genes (qnrS1), and colistin resistance genes (mcr-1.1, mcr-9).

The study identifies five key residue changes (L282S, A339T, D340N, V350I, and K351E) in Tet(X2) that enhance tigecycline resistance, demonstrating their critical role in the molecular evolution of Tet(X) towards high-level resistance.

The study identifies five key residue changes (L282S, A339T, D340N, V350I, and K351E) in Tet(X2) that enhance tigecycline resistance, demonstrating their critical role in the molecular evolution of Tet(X) towards high-level resistance.

The study identifies the prevalence of the tet(X4) gene in Escherichia coli isolates from duck farms in Southeast China, highlighting its association with resistance to multiple antibiotics including tigecycline, chlortetracycline, ampicillin, florfenicol, ciprofloxacin, gentamicin, trimethoprim/sulfamethoxazole, and fosfomycin.

The study identifies and characterizes the tigecycline resistance gene tet(X4) and a novel tet(A) variant, tet(A)-v, in Escherichia coli strains from swine farms, highlighting their role in multidrug resistance and the potential for horizontal gene transfer.

The study identifies tet(X4) as a gene that confers tigecycline resistance in E. coli, and develops an RNA-based assay (RBAST) to rapidly detect tet(X4)-positive strains.

The study identifies the mobilization of the tigecycline resistance gene tet(X4) by IS1 family elements in porcine Escherichia coli isolates, demonstrating the role of IS1 elements in the transposition of tet(X4) into the E. coli chromosome.

The study identifies mcr-1 and tet(X4) as genes conferring resistance to colistin and tigecycline, respectively, and characterizes plasmids coharboring these genes in Escherichia coli.

Tet(X4) exhibits high catalytic efficiency and confers resistance to tigecycline in E. coli. Amino acid substitutions L282S and V329M enhance its activity.

The study identifies novel tet(X) orthologs, including tet(X45), tet(X46), and tet(X47), which confer resistance to tigecycline and other tetracycline derivatives. It also traces the origins of tet(X) genes to Riemerella anatipestifer and highlights the role of Bacteroidaceae as a reservoir for these genes.

The study identifies the tet(X4) gene as a major cause of tigecycline resistance in various bacterial species isolated from pork samples, highlighting its widespread distribution and potential for horizontal gene transfer.

The study presents the MALDI Tet(X)-plus test, a rapid and reliable method for detecting Tet(X)-producers, non-Tet(X)-producing tetracycline-resistant, and tetracycline-susceptible Gram-negative bacteria. It identifies various tetracycline resistance genes such as tet(A), tet(B), tet(D), tet(G), tet(M), tet(X3), tet(X4), tet(X2)-tet(X6), tet(X3)-tet(X6), and TMexCD1-TOprJ1.

The study identified four tet(X) variants (tet(X3), tet(X4), tet(X6), and tet(X15)) in diverse bacterial species from chicken fecal samples, highlighting the widespread occurrence of tigecycline resistance in poultry farms.

The study reports the first identification of the plasmid-mediated tigecycline resistance gene tet(X4) in a clinical isolate of Klebsiella pneumoniae, highlighting the potential spread of this gene among important nosocomial pathogens.

Bismuth drugs, particularly bismuth nitrate, reverse tigecycline resistance conferred by the Tet(X4) protein in Gram-negative bacteria by inhibiting its enzymatic activity.

The study identifies the plasmid-mediated tigecycline resistance gene tet(X4) in Enterobacter cloacae isolates from pigs in China, demonstrating its transferability and association with multidrug resistance.

The study identifies multiple antimicrobial resistance genes in multidrug-resistant E. coli isolates from pig farms in China, including ESBL genes, fluoroquinolone resistance genes, carbapenem resistance genes, and colistin resistance genes. It highlights the widespread presence of these resistance mechanisms and their potential to spread to human pathogens.

The study identifies the presence of the bla KPC gene in Klebsiella pneumoniae isolates using long-read sequencing, highlighting its role in carbapenem resistance.

The study identifies the coexistence of tet(X4), mcr-1, and bla(NDM-5) in ST6775 Escherichia coli isolates from pigeons in China, highlighting the risk of multidrug-resistant pathogens.

The report highlights the presence of various antimicrobial resistance genes such as blaVIM-1, blaTEM-1B, blaTEM-1C, and cfr in different bacterial isolates, indicating resistance to carbapenems, beta-lactams, and macrolides/lincosamides/streptogramin B.

The study characterizes the fitness cost of tet(X4)-positive plasmids in E. coli, showing that these plasmids confer resistance to tetracyclines and other antibiotics, with varying impacts on bacterial growth and virulence.

The study identifies the emergence of tigecycline resistance gene tet(X4) in ST609 Escherichia coli isolates from wastewater in Turkey, highlighting the need for global surveillance of tet(X4)-bearing isolates.

The study identified mcr-1, tet(X4), and blaNDM-5 genes in Escherichia coli from food animals in eastern China, highlighting their role in resistance to colistin, tigecycline, and meropenem, respectively. These genes were found to be transferable via plasmids, emphasizing the potential for spread of antimicrobial resistance.

Probiotic supplementation in preterm infants reduces the diversity and persistence of antibiotic resistance genes in the gut microbiome, particularly targeting aminoglycoside, beta-lactam, tetracycline, and streptogramin resistance genes.

The study identified the presence of the tet(X4) gene in Escherichia coli isolates from a hospital in Beijing, China, highlighting the role of both clonal spread and horizontal gene transfer in the dissemination of tigecycline resistance.

The study identifies tet(X4) as a major cause of tigecycline resistance in E. coli ST761 isolates from a pig farm in China. The gene is located on a hybrid plasmid and is part of a multidrug resistance region that includes other resistance genes such as blaTEM-1, tet(A), tet(M), floR, qnrS1, sul3, dfrA5, and mef(B).

LI14, a synthetic antimicrobial peptide, displays potent antibacterial activity against multidrug-resistant pathogens, including those harboring blaNDM-1, mcr-1, tet(X4), and other resistance genes. It effectively kills bacteria, disrupts biofilms, and reduces persistence without inducing resistance.

The study identifies the plasmid-mediated tigecycline resistance gene tet(X4) in various Enterobacterales from porcine origins, highlighting its widespread dissemination and coexistence with other resistance genes such as blaNDM-1 and cfr. It also reports the first occurrence of tet(X4) in Morganella morganii and its coexistence with blaNDM-1 in a Klebsiella quasipneumoniae strain.

The study characterizes the plasmid-mediated high-level tigecycline resistance gene tet(X4) and its variants, highlighting their widespread occurrence in various bacterial species and environments.

The study identifies the coexistence of tet(X4), bla(NDM-1), and bla(OXA-58) in a porcine Acinetobacter towneri isolate, highlighting the complex resistance mechanisms involving tigecycline and carbapenem resistance.

The study identifies the presence of various tetracycline resistance genes (TRGs) in doxycycline-resistant E. coli (DRE) strains isolated from swine manure, highlighting the significant risk of tigecycline resistance. The tetX and tet(X4) genes were found to be strongly associated with tigecycline resistance.

The study identified several AMR genes in E. coli isolates from pigs and chickens in Zhejiang, China, including bla NDM-5, mcr-1, tet (X4), and cfr, which confer resistance to carbapenems, colistin, tigecycline, and multiple other antibiotics.

The study identified multiple antibiotic resistance genes (ARGs) in manure samples from a swine finishing facility, highlighting the prevalence of resistance to tetracyclines, macrolides, aminoglycosides, and other antibiotics. Key genes included tet(M), lnuA, erm(35), aadS, mphB, dfrG, vga-type ABC-F, lsa-type ABC-F, msr-type ABC-F, optrA, and others, primarily found in Firmicutes, Proteobacteria, and Bacteroidota. These genes were associated with resistance mechanisms such as target alteration, antibiotic inactivation, and efflux pumps.

The study identifies the first case of an XDR E. coli isolate co-harboring plasmid-mediated bla NDM-5 and tet (X4) genes, highlighting the coexistence of carbapenem and tigecycline resistance in a high-risk E. coli clone ST648 of human origin in China.

The study identified several antibiotic resistance genes in Riemerella anatipestifer, including OXA-209, erm(F), floR, aadS, tet(X), tet(X4), RanA, RanB, and ErmF, which confer resistance to various antibiotics such as beta-lactams, macrolides, fluoroquinolones, aminoglycosides, and tetracyclines.

The study identifies tet(X4) as a tigecycline resistance gene in E. coli and K. pneumoniae from pork samples, showing its transferability and association with multidrug resistance.

The study identified several AMR genes in avian strains of Escherichia fergusonii, including beta-lactamases (CTX-M, OXA, TEM), tetracycline resistance genes (Tet(X4)), and colistin resistance gene (MCR-1.1). Avian strains were found to have higher AMR dissemination potential compared to other sources.

The study identifies multiple antimicrobial resistance genes in Salmonella enterica isolates from China, highlighting the increasing prevalence of resistance to beta-lactams, quinolones, tetracyclines, and sulfonamides. Key genes include blaTEM-1B, blaCTX-M-14, aac(3)-IV, and mcr-1.

The study identifies the tet(X4) gene and other tetracycline resistance genes, along with efflux pumps, as contributors to high tigecycline resistance in E. fergusonii from pigs.

Two multidrug-resistant Klebsiella pneumoniae strains harboring the tigecycline-resistant gene tet(X4) were identified in China. The tet(X4) gene was found to be flanked by mobile elements IS 1R and IS CR2, facilitating its transmission. The plasmids carrying tet(X4) were transferable to Escherichia coli, demonstrating their potential for horizontal gene transfer.

The study identifies an E. coli strain co-harboring the tigecycline resistance gene tet(X4) and the virulence gene astA, highlighting the potential threat of such strains in causing disease and complicating treatment.

The study identified 53 resistance genes and 13 categories of 195 virulence factors in multidrug-resistant ETEC isolates from diarrheic pigs, including tet(A), floR, aph(3')-Ia, aadA2, bleO, sul3, dfrA12, QnrS1, and tet(X4).

The study identifies the presence of the tet(X4) gene in avian-derived E. coli strains in Sichuan Province, China, highlighting its location on mobile plasmids and its ability to confer tigecycline resistance. The gene was found to be stably transmitted under tigecycline selection pressure.

This review discusses the role of flavin-dependent monooxygenases (FMOs) and Baeyer-Villiger monooxygenases (BVMOs) in antibiotic resistance, focusing on their mechanisms in modifying antibiotics such as tetracyclines, rifamycins, and sulfonamides. Key genes like TetX, MabTetX, Tet56, RIFMO, SadA, SadB, SulX, and SulR were identified as conferring resistance through enzymatic modifications.

This review discusses the role of flavin-dependent monooxygenases (FMOs) and Baeyer-Villiger monooxygenases (BVMOs) in antibiotic resistance, focusing on their mechanisms in modifying antibiotics such as tetracyclines, rifamycins, and sulfonamides. Key genes like TetX, MabTetX, Tet56, RIFMO, SadA, SadB, SulX, and SulR were identified as conferring resistance through enzymatic modifications.

The study established a highly sensitive and specific LAMP assay for the detection of tet(X2/X3/X4/X5) genes, which confer resistance to tigecycline.

The study identifies tet(X4) and tmexCD1-toprJ1 as key genes contributing to tigecycline resistance in E. coli and K. pneumoniae isolates from hospital sewage, highlighting the role of plasmid-mediated resistance and efflux pump overexpression.

The study demonstrates the use of a CRISPR/Cas9 system to resensitize tigecycline- and colistin-resistant Escherichia coli by targeting the tet(X4) and mcr-1 genes, leading to plasmid loss and reduced resistance.

The study identifies that sub-MICs of host defense peptides, particularly indolicidin, inhibit the conjugative transfer of resistance plasmids carrying bla NDM and tet(X4) genes in physiologically relevant conditions.

The study identifies several AMR genes, including bla CTX-M-1, bla CTX-M-14b, bla SHV-12, tet(X3), and tet(X4), in Salmonella isolates from food-producing animals and human cases in the EU. These genes confer resistance to various antibiotics, highlighting the spread of multidrug-resistant Salmonella strains.

The study identifies the first occurrence of the tet(X4) gene in Klebsiella pneumoniae from wild birds in Pakistan, highlighting the potential spread of tigecycline resistance beyond E. coli.

The paper reviews the molecular mechanisms of tigecycline resistance in Enterobacterales, highlighting the roles of efflux pumps, tet genes, and other resistance mechanisms. It identifies several tigecycline resistance genes, including tet(X), tet(X1), tet(X2), tet(X3), tet(X4), tet(M), tet(A), tet(B), tet(Y), and others, along with their associated resistance profiles.

The study developed a one-tube RPA-CRISPR-Cas12b-based detection system for mcr-1 and tet(X4) with high sensitivity and specificity, enabling rapid and accurate identification of these resistance genes in pork and environmental samples.

The study identified multiple AMR genes in E. coli isolates from poultry in Bangladesh, including genes conferring resistance to various antibiotics such as tetracycline, ciprofloxacin, azithromycin, colistin, and others. High levels of multidrug resistance were observed, with specific genes like mcr1.1, bla CTX-M-65, and tet(A) playing significant roles.

The study identified several antimicrobial resistance genes in Morganella morganii, including bla KPC-2, mcr-1, tet(X4), and tmexCD-toprJ. Additionally, a novel bla KPC-2-bearing plasmid was discovered, highlighting the role of mobile genetic elements in the spread of resistance.

The study identifies the tigecycline resistance gene tet(X4) in Escherichia coli isolates from pigs and pork, highlighting its association with specific plasmid types and the potential for horizontal transfer.

The study identifies the plasmid-borne tet(X4) resistance gene in a clinical isolate of Klebsiella pneumoniae ST485, which confers resistance to tigecycline, eravacycline, and omadacycline. The gene was successfully transferred to E. coli DH5α, demonstrating its mobility and potential for spread.

The study identifies the tet(X4) gene in E. coli isolates from duck farms, demonstrating its presence in a circular intermediate and its ability to transfer via conjugation, highlighting the potential for widespread tigecycline resistance.

The study identified the tet(X4) gene in tigecycline-resistant Escherichia coli isolates from poultry and meat samples in Türkiye, highlighting its role in tigecycline resistance and its presence on IncX1 plasmids.

The study identifies the co-existence of fosA4, mcr-1, and tet(X4) genes in Escherichia coli isolates from wild birds in Pakistan, indicating the potential for horizontal gene transfer and the spread of multidrug-resistant plasmids.

The study characterizes the presence of mcr-1.1, mcr-3.5, blaCTX-M-55, and tet(X4) genes in clinical isolates of Enterobacterales from Thailand, highlighting their role in multidrug resistance and the potential for horizontal gene transfer.

The study identified the emergence of plasmid-mediated colistin resistance genes mcr-1 and mcr-3 in animals and humans in China, highlighting the significance of these genes in the spread of colistin resistance. Additionally, the tet(X4) gene was detected, indicating tetracycline resistance.

The study identifies a wide range of antibiotic resistance genes in the Enterobacter hormaechei complex, highlighting its multidrug-resistant nature and the role of mobile genetic elements in the dissemination of resistance.

The study identifies multiple extended-spectrum β-lactamase (ESBL) genes, including bla CTX-M, bla TEM, bla OXA, bla LAP, and bla CMY, as well as other antibiotic resistance genes such as mcr-1, mcr-1.1, tet(X4), aadA1, aadA2, aph(6)-Id, aph(3")-Ib, aph(3')-Ia, aph(3')-IIa, aac(3)-IVa, aph(4)-Ia, tet(A), tet(M), sul2, sul3, dfrA14, qnrS1, arr-2, fosA3, cmlA5, floR, mph(A), and lnu(F) in ESBL-producing E. coli isolates from pigeons in China.

The study identifies the presence of mcr-1.1, bla TEM, bla CTX-M−15, bla CTX-M−55, and other resistance genes in ESBL-producing E. coli isolates from the Jehai community in Malaysia, highlighting the co-occurrence of multiple antibiotic resistance mechanisms.

The study identifies Tet(X4) as a critical tetracycline destructase responsible for resistance to third-generation tetracyclines. It develops a fluorescence polarisation binding assay to discover inhibitors of Tet(X4), including phenothiazine derivatives and the 5-HT4 agonist tegaserod, which show promise in restoring tetracycline activity against resistant bacteria.

The study identifies the emergence of the transferable tigecycline and eravacycline resistance gene tet(X4) in Escherichia coli isolates from Iran, highlighting its potential to spread among animal and human populations.

The study identifies multiple antimicrobial resistance genes (ARGs) in Escherichia coli isolates from pet cafés, highlighting the role of plasmids in the transmission of these genes. Key ARGs include tet(X4), sul2, sul3, strA, strB, dfrA14, qnrS1, qnrS2, oqxB, blaCTX-M-15, blaCTX-M-14, blaCTX-M-65, floR, and tet(A).

The study identifies the tet(X4) gene as a key factor in tigecycline resistance in XDR E. coli strains from pet dogs, highlighting the role of plasmid fusion in overcoming temperature sensitivity and promoting resistance gene dissemination.

The study reports the detection of SXT/R391 integrative conjugative elements carrying tigecycline resistance genes tet(X4) and tmexCD2-toprJ2 in Shewanella spp. isolated from retail seafood. These genes were found to be located on novel members of the SXT/R391 family of ICEs, highlighting the potential for horizontal gene transfer of tigecycline resistance among aquatic bacteria.

The study identified 50 acquired resistance genes and seven chromosomal-mediated gene mutations in Salmonella populations from Thai canal water, highlighting the prevalence of multidrug-resistant strains and the diversity of resistance mechanisms.

The study identifies various antimicrobial resistance genes in E. coli isolates from Hong Kong, including blaTEM-1, floR, tet(A), aph(3')-Ia, blaNDM, tet(X4), and mcr, which confer resistance to multiple antibiotics.

The study identifies a Klebsiella pneumoniae ST14 strain co-harboring bla NDM-1, bla OXA-232, mcr-1.1, and a novel IncI1 tet(X4) plasmid, highlighting the complex resistance profile and potential for horizontal gene transfer under antibiotic pressure.

The study identifies a Klebsiella pneumoniae ST14 strain co-harboring bla NDM-1, bla OXA-232, mcr-1.1, and a novel IncI1 tet(X4) plasmid, highlighting the complex resistance profile and potential for horizontal gene transfer under antibiotic pressure.

The study identifies the plasmid-mediated tigecycline resistance gene tet(x4) and the New Delhi metallo-beta-lactamase (NDM) in an Escherichia coli isolate from Canada, highlighting the emergence of a high-risk multidrug-resistant clone.

The study identifies tet(X4)-positive multidrug-resistant E. coli in healthy individuals from urban areas in Shenzhen, China, highlighting the presence of tigecycline resistance and other resistance genes in the community gut microbiota.

The study identifies multiple antimicrobial resistance genes in Escherichia coli from poultry and other food-producing animals in China, highlighting the prevalence of beta-lactamases, tetracycline resistance genes, aminoglycoside modifying enzymes, quinolone resistance genes, and sulfonamide resistance genes.

Mefloquine was identified as a synergistic agent with tetracyclines against Tet(X3/X4)-positive E. coli, demonstrating inhibitory effects on Tet(X4) activity and disrupting bacterial energy metabolism.

Arsenic and microplastics significantly influenced the spread of antibiotic resistance genes (ARGs) during vermicomposting, with specific genes like bla ampC, bla LRA-1, bla FEZ-1, aph(3′)-II, ermB, vanY, mefA, catA, tetX4, bla IMP-11, aadK, ant(3′)-Ih-aac(6′)-Id, ermG, bla OXA-119, tetR, vatE, smeE, mexD, bla OXA-3, amrB, tetY, class A beta-lactamase, dfrA1, alanine adenosyltransferase JOHN-1, mdtB, mdtE, and erm-41 being enriched under various treatment conditions.