The study characterizes the tetracycline destructase enzymes Tet(50), Tet(X), and Tet(X)_3, highlighting their roles in tetracycline inactivation and the development of anhydrotetracycline analogs as inhibitors.

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 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 study reports three tigecycline-resistant Acinetobacter towneri strains co-harboring the tet(X3) and bla(OXA-58) genes on plasmids, highlighting the potential for horizontal gene transfer and increased antibiotic resistance.

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 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 tet(X3) and tet(X6) as prevalent tetracycline resistance genes in livestock-associated Acinetobacter, highlighting their sporadic dissemination and the role of diverse plasmidomes in their spread.

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 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 identified various ESBL and carbapenemase genes, including bla NDM-1, bla OXA-48-like, bla CTX-M-15, bla SHV, bla OXA-1, and tet(X3), in environmental samples from a Ghanaian hospital, highlighting the presence of multidrug-resistant gram-negative bacteria.

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 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 identifies and characterizes tet(X)-carrying plasmids in Acinetobacter species, highlighting the role of GR31 plasmids in mediating tigecycline resistance and their potential to spread among various Acinetobacter species.

The study identified NDM-1-producing Shewanella spp. and Acinetobacter portensis co-harboring tet(X3) in a Chinese dairy farm. bla NDM-1 and tet(X3) were found on a non-conjugative plasmid and the chromosome, respectively. The study also confirmed the presence of a circular intermediate ΔIS CR2-tet(X3)-bla NDM-1.

Seven novel tet(X3) variants were identified in Acinetobacter species, with tet(X3.7) and tet(X3.9) showing increased tigecycline resistance when expressed in E. coli JM109.

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 reports the earliest observation of the tetracycline destructase gene tet(X3) in a clinical strain of Acinetobacter junii isolated in 2004, predating tigecycline's commercialization, indicating potential alternative selective pressures for its emergence.

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 identifies the presence of tet(x3), bla NDM-1, and bla OXA-97 genes in carbapenem-resistant Acinetobacter baumannii isolates from the Netherlands, which confer resistance to eravacycline, omadacycline, and carbapenems.

The study identifies multiple ESBL genes, including bla CTX-M, bla TEM, and bla SHV, along with other resistance genes such as bla OXA-1, bla KPC-2, bla NDM-1, and others, contributing to multidrug resistance in E. coli ST410 isolates from pediatric infections in Shenzhen, China.

The study identifies specific tetracycline resistance mechanisms (efflux pumps, ribosomal protection proteins, and type 1 tetracycline destructases) that are preferentially selected by different generations of tetracycline antibiotics, highlighting the evolutionary dynamics of resistance.

The study identifies the tet(X3) gene as a major cause of tigecycline resistance in Escherichia coli and demonstrates that exogenous adenosine can restore tigecycline susceptibility by enhancing oxidative stress and disrupting bacterial cell membranes.

The study identifies a novel Acinetobacter species co-harboring chromosomal tet(X3) and plasmid-associated bla(NDM-1) genes, demonstrating resistance to multiple antibiotics including carbapenems and tetracyclines.

The study identifies multiple acquired antimicrobial resistance genes in Acinetobacter baumannii International Clone 12, including bla OXA-23, bla GES-11, bla GES-12, bla GES-22, bla GES-35, bla CARB-16, bla CARB-49, aphA6a, aadB, strA, strB, cmlA1, aadA2b, sul1, drfA7, dfrA1, qacE, tet(B), tet(X3), msr(E), mph(E), bla TEM-1B, and aacC3. These genes contribute to resistance against various antibiotics, highlighting the complexity of resistance mechanisms in this clone.