scholarly journals A New Tetracycline Efflux Gene, tet(40), Is Located in Tandem with tet(O/32/O) in a Human Gut Firmicute Bacterium and in Metagenomic Library Clones

2008 ◽  
Vol 52 (11) ◽  
pp. 4001-4009 ◽  
Author(s):  
Katarzyna A. Kazimierczak ◽  
Marco T. Rincon ◽  
Andrea J. Patterson ◽  
Jennifer C. Martin ◽  
Pauline Young ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Metagenomic Library ◽  
Tetracycline Resistance ◽  
Mobile Element ◽  
Amino Acid Identity ◽  
Donor Strain ◽  
Human Gut ◽  
Efflux Pump Inhibitor ◽  
E Coli ◽  
Tetracycline Resistance Genes

ABSTRACT The bacterium Clostridium saccharolyticum K10, isolated from a fecal sample obtained from a healthy donor who had received long-term tetracycline therapy, was found to carry three tetracycline resistance genes: tet(W) and the mosaic tet(O/32/O), both conferring ribosome protection-type resistance, and a novel, closely linked efflux-type resistance gene designated tet(40). tet(40) encodes a predicted membrane-associated protein with 42% amino acid identity to tetA(P). Tetracycline did not accumulate in Escherichia coli cells expressing the Tet(40) efflux protein, and resistance to tetracycline was reduced when cells were incubated with an efflux pump inhibitor. E. coli cells carrying tet(40) had a 50% inhibitory concentration of tetracycline of 60 μg/ml. Analysis of a transconjugant from a mating between donor strain C. saccharolyticum K10 and the recipient human gut commensal bacterium Roseburia inulinivorans suggested that tet(O/32/O) and tet(40) were cotransferred on a mobile element. Sequence analysis of a 37-kb insert identified on the basis of tetracycline resistance from a metagenomic fosmid library again revealed a tandem arrangement of tet(O/32/O) and tet(40), flanked by regions with homology to parts of the VanG operon previously identified in Enterococcus faecalis. At least 10 of the metagenomic inserts that carried tet(O/32/O) also carried tet(40), suggesting that tet(40), although previously undetected, may be an abundant efflux gene.

scholarly journals Novel Tetracycline Resistance Determinant Isolated from an Environmental Strain of Serratia marcescens

2007 ◽  
Vol 73 (7) ◽  
pp. 2199-2206 ◽  
Author(s):  
Stuart A. Thompson ◽  
Elizabeth V. Maani ◽  
Angela H. Lindell ◽  
Catherine J. King ◽  
J. Vaun McArthur
Keyword(s):  
Serratia Marcescens ◽  
Efflux Pump ◽  
Tetracycline Resistance ◽  
Amino Acid Identity ◽  
Resistance Determinant ◽  
Mercury Resistance ◽  
Resistance Locus ◽  
Environmental Strain ◽  
Apparent Lack ◽  
E Coli

ABSTRACT Resistances to tetracycline and mercury were identified in an environmental strain of Serratia marcescens isolated from a stream highly contaminated with heavy metals. As a step toward addressing the mechanisms of coselection of heavy metal and antibiotic resistances, the tetracycline resistance determinant was cloned in Escherichia coli. Within the cloned 13-kb segment, the tetracycline resistance locus was localized by deletion analysis and transposon mutagenesis. DNA sequence analysis of an 8.0-kb region revealed a novel gene [tetA(41)] that was predicted to encode a tetracycline efflux pump. Phylogenetic analysis showed that the TetA(41) protein was most closely related to the Tet(39) efflux protein of Acinetobacter spp. yet had less than 80% amino acid identity with known tetracycline efflux pumps. Adjacent to the tetA(41) gene was a divergently transcribed gene [tetR(41)] predicted to encode a tetracycline-responsive repressor protein. The tetA(41)-tetR(41) intergenic region contained putative operators for TetR(41) binding. The tetA(41) and tetR(41) promoters were analyzed using lacZ fusions, which showed that the expression of both the tetA(41) and tetR(41) genes exhibited TetR(41)-dependent regulation by subinhibitory concentrations of tetracycline. The apparent lack of plasmids in this S. marcescens strain, as well as the presence of metabolic genes adjacent to the tetracycline resistance locus, suggested that the genes were located on the S. marcescens chromosome and may have been acquired by transduction. The cloned Tet 41 determinant did not confer mercury resistance to E. coli, confirming that Tet 41 is a tetracycline-specific efflux pump rather than a multidrug transporter.

Detection of efflux pump genes in multiresistant Acinetobacter baumannii ST2 in Iran

2021 ◽  
Author(s):  
Zahra Meshkat ◽  
Himen Salimizand ◽  
Yousef Amini ◽  
Davood Mansury ◽  
Abolfazl Rafati Zomorodi ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Efflux Pump ◽  
Tetracycline Resistance ◽  
Genomic Diversity ◽  
Expression Level ◽  
Tetracycline Resistance Genes ◽  
Microdilution Method ◽  
Relationship Of ◽  
Repetitive Extragenic Palindromic Pcr

AbstractAcinetobacter baumannii, as a nosocomial pathogen has become a worldwide concern in recent years. In the current study, the resistance to tetracyclines and colistin were assessed in the isolates from different provinces of Iran.During the timeline of this study, a number of 270 isolates of A. baumannii were collected from tracheal aspirates, wounds, urine and blood cultures. The minimum inhibitory concentration (MIC) for tetracycline, doxycycline, minocycline, tigecycline and colistin were evaluated. Tetracycline resistance genes were assessed by PCR. The mean expression level of adeB, adeJ and adeG were assessed using semi quantitative Real-Time PCR. The clonal relationship of the isolates was evaluated by the repetitive extragenic palindromic PCR (REP-PCR), International Clonal (IC) Lineage Multiplex PCR and multilocus sequence typing (MLST) (Pasteur scheme) methods.The MIC by microdilution method showed that 87.5, 51.4, 28, 0.74 and 0% of the isolates were resistant to tetracycline, doxycycline, minocycline, tigecycline and colistin respectively. The prevalence of tetracycline resistance genes was 99.2, 99.2, 98, 86.7, 10, 3.33, 0.37, 0% for adeB, adeJ, adeG, tetB, tetA(39), tetA, tetM and tetH in tetracycline-resistant isolates. Moreover, the expression level of adeB, adeJ, adeG genes in tigecycline-nonsusceptible A. baumannii (TNAB) strain was higher compared to the tigecycline-susceptible A. baumannii (TSAB). A broad genomic diversity was revealed, but ST2 was the most prevalent ST. Our results indicated that tetracycline resistance in Iran is mediated by resistance-nodulation-cell division (RND) and tetB efflux pumps.

scholarly journals Detection of a Novel, and Likely Ancestral, Tn916-Like Element from a Human Saliva Metagenomic Library

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 548
Author(s):  
Liam J. Reynolds ◽  
Muna F. Anjum ◽  
Adam P. Roberts
Keyword(s):  
Resistance Genes ◽  
Metagenomic Library ◽  
Tetracycline Resistance ◽  
Human Saliva ◽  
Fusion Event ◽  
Tetracycline Resistance Genes ◽  
Antimicrobial Resistance Genes ◽  
Genes Encoding ◽  
Gene Fusion Event ◽  
Metagenomic Approach

Tn916 is a conjugative transposon (CTn) and the first reported and most well characterised of the Tn916/Tn1545 family of CTns. Tn916-like elements have a characteristic modular structure and different members of this family have been identified based on similarities and variations in these modules. In addition to carrying genes encoding proteins required for their conjugation, Tn916-like elements also carry accessory, antimicrobial resistance genes; most commonly the tetracycline resistance gene, tet(M). Our study aimed to identify and characterise tetracycline resistance genes from the human saliva metagenome using a functional metagenomic approach. We identified a tetracycline-resistant clone, TT31, the sequencing of which revealed it to encode both tet(M) and tet(L). Comparison of the TT31 sequence with the accessory, regulation, and recombination modules of other Tn916-like elements indicated that a partial Tn916-like element encoding a truncated orf9 was cloned in TT31. Analysis indicated that a previous insertion within the truncated orf9 created the full length orf9 found in most Tn916-like transposons; demonstrating that orf9 is, in fact, the result of a gene fusion event. Thus, we hypothesise that the Tn916-like element cloned in TT31 likely represents an ancestral Tn916.

scholarly journals Prevalence of Antimicrobial Resistance and Transfer of Tetracycline Resistance Genes in Escherichia coli Isolates from Beef Cattle

2015 ◽  
Vol 81 (16) ◽  
pp. 5560-5566 ◽  
Author(s):  
Seung Won Shin ◽  
Min Kyoung Shin ◽  
Myunghwan Jung ◽  
Kuastros Mekonnen Belaynehe ◽  
Han Sang Yoo
Keyword(s):  
Escherichia Coli ◽  
South Korea ◽  
Beef Cattle ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Tetracycline Resistance ◽  
Tetracycline Resistance Gene ◽  
Content Type ◽  
E Coli ◽  
Tetracycline Resistance Genes

ABSTRACTThe aim of this study was to investigate the prevalence and transferability of resistance in tetracycline-resistantEscherichia coliisolates recovered from beef cattle in South Korea. A total of 155E. coliisolates were collected from feces in South Korea, and 146 were confirmed to be resistant to tetracycline. The tetracycline resistance genetet(A) (46.5%) was the most prevalent, followed bytet(B) (45.1%) andtet(C) (5.8%). Strains carryingtet(A) plustet(B) andtet(B) plustet(C) were detected in two isolates each. In terms of phylogenetic grouping, 101 (65.2%) isolates were classified as phylogenetic group B1, followed in decreasing order by D (17.4%), A (14.2%), and B2 (3.2%). Ninety-one (62.3%) isolates were determined to be multidrug resistant by the disk diffusion method. MIC testing using the principal tetracyclines, namely, tetracycline, chlortetracycline, oxytetracycline, doxycycline, and minocycline, revealed that isolates carryingtet(B) had higher MIC values than isolates carryingtet(A). Conjugation assays showed that 121 (82.9%) isolates could transfer a tetracycline resistance gene to a recipient via the IncFIB replicon (65.1%). This study suggests that the high prevalence of tetracycline-resistantE. coliisolates in beef cattle is due to the transferability of tetracycline resistance genes betweenE. colipopulations which have survived the selective pressure caused by the use of antimicrobial agents.

scholarly journals Photodynamic Inactivation of Bacteria with Porphyrin Derivatives: Effect of Charge, Lipophilicity, ROS Generation, and Cellular Uptake on Their Biological Activity In Vitro

2020 ◽  
Vol 21 (22) ◽  
pp. 8716
Author(s):  
Adam Sułek ◽  
Barbara Pucelik ◽  
Marcin Kobielusz ◽  
Agata Barzowska ◽  
Janusz M. Dąbrowski
Keyword(s):  
Cellular Uptake ◽  
Efflux Pump ◽  
Theoretical Calculations ◽  
Resistant Bacteria ◽  
Ros Generation ◽  
Photodynamic Inactivation ◽  
Efflux Pump Inhibitor ◽  
E Coli ◽  
Charge Interaction

Resistance of microorganisms to antibiotics has led to research on various therapeutic strategies with different mechanisms of action, including photodynamic inactivation (PDI). In this work, we evaluated a cationic, neutral, and anionic meso-tetraphenylporphyrin derivative’s ability to inactivate the Gram-negative and Gram-positive bacteria in a planktonic suspension under blue light irradiation. The spectroscopic, physicochemical, redox properties, as well as reactive oxygen species (ROS) generation capacity by a set of photosensitizers varying in lipophilicity were investigated. The theoretical calculations were performed to explain the distribution of the molecular charges in the evaluated compounds. Moreover, logP partition coefficients, cellular uptake, and phototoxicity of the photosensitizers towards bacteria were determined. The role of a specific microbial efflux pump inhibitor, verapamil hydrochloride, in PDI was also studied. The results showed that E. coli exhibited higher resistance to PDI than S. aureus (3–5 logs) with low light doses (1–10 J/cm2). In turn, the prolongation of irradiation (up to 100 J/cm2) remarkably improved the inactivation of pathogens (up to 7 logs) and revealed the importance of photosensitizer photostability. The PDI potentiation occurs after the addition of KI (more than 3 logs extra killing). Verapamil increased the uptake of photosensitizers (especially in E. coli) due to efflux pump inhibition. This effect suggests that PDI is mediated by ROS, the electrostatic charge interaction, and the efflux of photosensitizers (PSs) regulated by multidrug-resistance (MDR) systems. Thus, MDR inhibition combined with PDI gives opportunities to treat more resistant bacteria.

scholarly journals Genotypic antimicrobial resistance characterization of E. coli from dairy calves at high risk of respiratory disease administered enrofloxacin or tulathromycin

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
R. V. Pereira ◽  
C. Foditsch ◽  
J. D. Siler ◽  
S. C. Dulièpre ◽  
C. Altier ◽  
...  
Keyword(s):  
High Risk ◽  
Antimicrobial Resistance ◽  
Respiratory Disease ◽  
Resistance Genes ◽  
Tetracycline Resistance ◽  
Control Group ◽  
E Coli ◽  
Tetracycline Resistance Genes ◽  
Antimicrobial Resistance Genes

Abstract The objective of this study was to evaluate the longitudinal effect of enrofloxacin or tulathromycin use in calves at high risk of bovine respiratory disease (BRD) on antimicrobial resistance genes and mutation in quinolone resistance-determining regions (QRDR) in fecal E. coli. Calves at high risk of developing BRD were randomly enrolled in one of three groups receiving: (1) enrofloxacin (ENR; n = 22); (2) tulathromycin (TUL; n = 24); or (3) no treatment (CTL; n = 21). Fecal samples were collected at enrollment and at 7, 28, and 56 days after beginning treatment, cultured for Escherichiacoli (EC) and DNA extracted. Isolates were screened for cephalosporin, quinolone and tetracycline resistance genes using PCR. QRDR screening was conducted using Sanger sequencing. The only resistance genes detected were aac(6′)Ib-cr (n = 13), bla-CTX-M (n = 51), bla-TEM (n = 117), tetA (n = 142) and tetB (n = 101). A significantly higher detection of gyrA mutated at position 248 at time points 7 (OR = 11.5; P value = 0.03) and 28 (OR = 9.0; P value = 0.05) was observed in the ENR group when compared to calves in the control group. Our findings support a better understanding of the potential impacts from the use of enrofloxacin in calves on the selection and persistence of resistance.

scholarly journals Occurrence of Tetracycline Resistance Genes among Escherichia coli Isolates from the Phase 3 Clinical Trials for Tigecycline

2007 ◽  
Vol 51 (9) ◽  
pp. 3205-3211 ◽  
Author(s):  
Margareta Tuckman ◽  
Peter J. Petersen ◽  
Anita Y. M. Howe ◽  
Mark Orlowski ◽  
Stanley Mullen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clinical Trials ◽  
Tetracycline Resistance ◽  
Phase 3 ◽  
E Coli ◽  
Tetracycline Resistance Genes ◽  
Resistance Determinants ◽  
Resistant Strains ◽  
A Current ◽  
Antibacterial Spectrum

ABSTRACT Tigecycline, a member of the glycylcycline class of antibiotics, was designed to maintain the antibacterial spectrum of the tetracyclines while overcoming the classic mechanisms of tetracycline resistance. The current study was designed to monitor the prevalence of the tet(A), tet(B), tet(C), tet(D), tet(E), and tet(M) resistance determinants in Escherichia coli isolates collected during the worldwide tigecycline phase 3 clinical trials. A subset of strains were also screened for the tet(G), tet(K), tet(L), and tet(Y) genes. Of the 1,680 E. coli clinical isolates screened for resistance to classical tetracyclines, 405 (24%) were minocycline resistant (MIC ≥ 8 μg/ml) and 248 (15%) were tetracycline resistant (MIC ≥ 8 μg/ml) but susceptible to minocycline (MIC ≤ 4 μg/ml). A total of 452 tetracycline-resistant, nonduplicate isolates were positive by PCR for at least one of the six tetracycline resistance determinants examined. Over half of the isolates encoding a single determinant were positive for tet(A) (26%) or tet(B) (32%) with tet(C), tet(D), tet(E), and tet(M), collectively, found in 4% of isolates. Approximately 33% of the isolates were positive for more than one resistance determinant, with the tet(B) plus tet(E) combination the most highly represented, found in 11% of isolates. The susceptibilities of the tetracycline-resistant strains to tigecycline (MIC90, 0.5 μg/ml), regardless of the encoded tet determinant(s), were comparable to the tigecycline susceptibility of tetracycline-susceptible strains (MIC90, 0.5 μg/ml). The results provide a current (2002 to 2006) picture of the distribution of common tetracycline resistance determinants encoded in a globally sourced collection of clinical E. coli strains.

scholarly journals Effects of Chlorophyll-Derived Efflux Pump Inhibitor Pheophorbide a and Pyropheophorbide a on Growth and Macrolide Antibiotic Resistance of Indicator and Anaerobic Swine Manure Bacteria

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Mareike Kraatz ◽  
Terence R. Whitehead ◽  
Michael A. Cotta ◽  
Mark A. Berhow ◽  
Mark A. Rasmussen
Keyword(s):  
Bacterial Resistance ◽  
Efflux Pump ◽  
Growth Parameters ◽  
Swine Manure ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Pheophorbide A ◽  
Efflux Pump Inhibitor ◽  
E Coli ◽  
Pyropheophorbide A

Natural plant compounds, such as the chlorophyll a catabolites pheophorbide a (php) and pyropheophorbide a (pyp), are potentially active in the gastrointestinal tracts and manure of livestock as antimicrobial resistance-modifying agents through inhibition of bacterial efflux pumps. To investigate whether php, a known efflux pump inhibitor, and pyp influence bacterial resistance, we determined their long-term effects on the MICs of erythromycin for reference strains of clinically relevant indicator bacteria with macrolide or multidrug resistance efflux pumps. Pyp reduced the final MIC endpoint for Staphylococcus (S.) aureus and Escherichia (E.) coli by up to 1536 and 1024 μg erythromycin mL−1 or 1.4- and 1.2-fold, respectively. Estimation of growth parameters of S. aureus revealed that pyp exerted an intrinsic inhibitory effect under anaerobic conditions and was synergistically active, thereby potentiating the effect of erythromycin and partially reversing high-level erythromycin resistance. Anaerobe colony counts of total and erythromycin-resistant bacteria from stored swine manure samples tended to be lower in the presence of pyp. Tylosin, php, and pyp were not detectable by HPLC in the manure or medium. This is the first study showing that pyp affects growth and the level of sensitivity to erythromycin of S. aureus, E. coli, and anaerobic manure bacteria.

scholarly journals 1-benzyl-1,4-diazepane reduces the efflux of resistance-nodulation-cell division pumps in Escherichia coli

2020 ◽  
Vol 15 (11) ◽  
pp. 987-999
Author(s):  
Enrico Casalone ◽  
Tiziano Vignolini ◽  
Laura Braconi ◽  
Lucia Gardini ◽  
Marco Capitanio ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ethidium Bromide ◽  
Inhibitory Concentration ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Efflux Pump Inhibitor ◽  
E Coli ◽  
Microdilution Method ◽  
Photoactivated Localization Microscopy ◽  
Mixed Mechanism

Aim: To investigate the action mechanism of 1-benzyl-1,4-diazepane (1-BD) as efflux pump inhibitor (EPI) in Escherichia coli mutants: Δ acrAB or overexpressing AcrAB and AcrEF efflux pumps. Materials & methods: Effect of 1-BD on: antibiotic potentiation, by microdilution method; membrane functionality, by fluorimetric assays; ethidium bromide accumulation, by fluorometric real-time efflux assay; AcrB expression, by quantitative photoactivated localization microscopy. Results: 1-BD decreases the minimal inhibitory concentration of levofloxacin and other antibiotics and increase ethidium bromide accumulation in E. coli overexpressing efflux pumps but not in the Δ acrAB strain. 1-BD increases membranes permeability, without sensibly affecting inner membrane polarity and decreases acrAB transcription. Conclusion: 1-BD acts as an EPI in E. coli with a mixed mechanism, different from that of major reference EPIs.

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