Inactivation Of Tetracycline Research Articles

Cerium-Doped TiO2 and Sepiolite Nanocomposites for Tetracycline Inactivation in Water Treatment

Cerium-Doped TiO₂ and Sepiolite Nanocomposites for Tetracycline Inactivation in Water Treatment

Mitigating mechanism of nZVI-C on the inhibition of anammox consortia under long-term tetracycline hydrochloride stress: Extracellular polymeric substance properties and microbial community evolution

In this study, activated carbon-loaded nano-zero-valent iron (nZVI-C) composites were added to anaerobic ammonium oxidation bacteria (AnAOB) to overcome the inhibition of tetracycline hydrochloride (TCH). Results showed that 500 mg L−1 nZVI-C effectively mitigated the long-term inhibition of 1.5 mg L−1 TCH on AnAOB and significantly improved the total nitrogen removal efficiency (TNRE) (from 65.27% to 86.99%). Spectroscopic analysis revealed that nZVI-C increased the content of N–H and CO groups in EPS, which contributed to the adsorption of TCH. The accumulation of humic acid-like substances in EPS was also conducive to strengthening the extracellular defense level. In addition, TCH-degrading bacteria (Clostridium and Mycobacterium) were enriched in situ, and the abundance of Ca. Brocadia was significantly increased (from 10.69% to 18.59%). Furthermore, nZVI-C increased the abundance of genes encoding tetracycline inactivation (tetX), promoted mineralization of TCH by 90%, weakening the inhibition of TCH on microbial nitrogen metabolism. nZVI-C accelerated the electron consumption of anammox bacteria by upregulating the abundance of electron generation genes (nxrA, hdh) and providing electrons directly.

Rapid detection of plasmid-mediated high-level tigecycline resistance in Escherichia coli and Acinetobacter spp.

The emergence and spread of plasmid-encoded tet(X3/X4) genes that confer high-level tigecycline and eravacycline resistance in Escherichia coli and Acinetobacter spp. pose serious threats to human and animal health. We developed a rapid and robust assay to detect Tet(X3/X4) in Gram-negative bacteria based on eravacycline degradation by the presence of the Tet(X) enzyme in the test strain. This tetracycline inactivation method (TIM) is based on the degradation of eravacycline by the Tet(X3/X4)-producing strain, which results in reduced eravacycline activity against an acid-producing thermophile Bacillus stearothermophilus indicator strain. For Tet(X)-negative strains, eravacycline retains its antimicrobial activity. Coupled with a pH-sensitive dye (bromocresol purple), the reduced colorimetric inhibition zone can be measured to determine the production of Tet(X3/X4). One hundred and eighteen isolates, including 30 tet(X4)-positive E. coli, 30 tet(X3)-positive Acinetobacter spp. and 58 tet(X)-negative E. coli and Acinetobacter spp., were examined to evaluate the performance of this TIM. The sensitivity and specificity for E. coli carrying tet(X4) was 96.7% and 100%, respectively, and for Acinetobacter spp. carrying tet(X3) both were 100%. The TIM assay can be completed within 6.5 h. The TIM is a simple, rapid and cost-effective method for the detection of plasmid-mediated high-level tigecycline resistance in E. coli and Acinetobacter spp.

Inactivation and change of tetracycline-resistant Escherichia coli in secondary effluent by visible light-driven photocatalytic process using Ag/AgBr/g-C3N4

Control of antibiotic-resistant bacteria (ARB) and their related genes in secondary effluents has become a serious issue because of increased awareness of their health risks. A considerable number of techniques have been developed in recent years, particularly in relation to advanced oxidation. However, limited information is known about cellular behavior and resistance characteristic change during photocatalytic treatment. In this study, the inactivation of tetracycline (TC)-resistant Escherichia coli (TC-E. coli), removal of TC-resistant genes (TC-RGs), and antibiotic susceptibility were evaluated by employing photocatalytic treatment using Ag/AgBr/g-C3N4 with visible light irradiation. The effects of light intensity, photocatalyst dosage, and reaction ambient temperature on photocatalysis were modelled and investigated. The rate of TC-E. coli removal was also optimized. Results demonstrated that the optimal conditions for TC-E. coli removal included light intensity of 96.0 mW/cm2, photocatalyst dosage of 211.0 mg/L, and reaction ambient temperature of 23.7 °C. Under such conditions, the ARB removal rate was 6.1 log after 90 min and the related TC-RG removal rates were 49%, 86%, 69%, and 86% for tetA, tetM, tetQ, and intl1, respectively. The minimum inhibitory concentration test after photocatalysis shows that the antibiotic resistance of TC-E. coli was enhanced, which may be mainly due to the changes in the membrane potential and resulted in difficulty in destroying the bacteria through antibiotic contact. Hence, photocatalytic treatment could be an ideal method for ARB and antibiotic-resistant gene (ARG) control in wastewater, but the health risks of the remaining ARB and ARG should be investigated further.

Plasticity, dynamics, and inhibition of emerging tetracycline resistance enzymes.

While tetracyclines are an important class of antibiotics in agriculture and the clinic, their efficacy is threatened by increasing resistance. Resistance to tetracyclines can occur through efflux, ribosomal protection, or enzymatic inactivation. Surprisingly, tetracycline enzymatic inactivation has remained largely unexplored despite providing the distinct advantage of antibiotic clearance. The tetracycline destructases are a recently-discovered family of tetracycline-inactivating flavoenzymes from pathogens and soil metagenomes with a high potential for broad dissemination. Here, we show tetracycline destructases accommodate tetracycline-class antibiotics in diverse and novel orientations for catalysis, and antibiotic binding drives unprecedented structural dynamics facilitating tetracycline inactivation. We identify a key inhibitor binding mode that locks the flavin adenine dinucleotide cofactor in an inactive state, functionally rescuing tetracycline activity. Our results reveal the potential of a novel tetracycline/tetracycline destructase inhibitor combination therapy strategy to overcome resistance by enzymatic inactivation and restore the use of an important class of antibiotics.

The Tetracycline Destructases: A Novel Family of Tetracycline-Inactivating Enzymes

Enzymes capable of inactivating tetracycline are paradoxically rare compared with enzymes that inactivate other natural-product antibiotics. We describe a family of flavoenzymes, previously unrecognizable as resistance genes, which are capable of degrading tetracycline antibiotics. From soil functional metagenomic selections, we discovered nine genes that confer high-level tetracycline resistance by enzymatic inactivation. We also demonstrate that a tenth enzyme, an uncharacterized homolog in the human pathogen Legionella longbeachae, similarly inactivates tetracycline. These enzymes catalyze the oxidation of tetracyclines in vitro both by known mechanisms and via previously undescribed activity. Tetracycline-inactivation genes were identified in diverse soil types, encompass substantial sequence diversity, and are adjacent to genes implicated in horizontal gene transfer. Because tetracycline inactivation is scarcely observed in hospitals, these enzymes may fill an empty niche in pathogenic organisms, and should therefore be monitored for their dissemination potential into the clinic.

Wastewater disinfection by solar heterogeneous photocatalysis: effect on tetracycline resistant/sensitive Enterococcus strains

<div> <p>Solar simulated heterogeneous photocatalysis (SSHP) with suspended TiO<sub>2</sub> was investigated in the inactivation of tetracycline resistant/sensitive <em>Enterococcus</em> (TRE/TSE) strains in the effluent of an urban wastewater treatment plant (UWTP). The effect of solar simulated disinfection (SSD) on the inactivation of the same <em>Enterococcus</em> strains was investigated as control. SSHP process (0.05 g l<sup>-1</sup> of TiO<sub>2</sub>) was found to be effective in the inactivation of both <em>Enterococcus</em> strains with total inactivation (~7 log unit) observed after 60 min of irradiation. On the contrary, SSD process did not show any significant inactivation after 90 min of irradiation. The effect of both processes on the antibiotic resistance phenotypes of the surviving enterococci was also evaluated. TRE cells surviving the SSHP treatment showed that disinfection process did not affect the antibiotic resistance pattern after 45 min irradiation. The same was observed for the TSE strain. Accordingly, antibiotic resistance can spread into the receiving water body when antibiotic resistant strains survive to disinfection process.</p> </div> <p> </p>

Erratum: Acquired antibiotic resistance genes: an overview

OPINION article Front. Microbiol., 16 November 2012Sec. Antimicrobials, Resistance and Chemotherapy Volume 3 - 2012 | https://doi.org/10.3389/fmicb.2012.00384

Degradation and inactivation of tetracycline by TiO 2 photocatalysis

To compare tetracycline abatement efficiency, tetracycline solutions were irradiated in aqueous suspensions of TiO 2 with three different light sources: a UV lamp, a solarium device and a UV-A lamp. Negligible degradation was observed when irradiations were performed in absence of TiO 2. In contrast, rapid tetracycline degradation was observed in the presence of 0.5 g l −1 of TiO 2. Close to 50% of its initial concentration was eliminated after 10, 20 and 120 min when the irradiation source used was a UV lamp, a solarium device and a UV-A lamp, respectively. Significant mineralization was also obtained when the UV lamp and solarium were used for photocatalysis. The antibacterial activity of selected microorganisms was drastically inhibited when exposed to tetracycline solutions treated by the photocatalyst over short irradiation periods.

A tetracycline efflux gene on Bacteroides transposon Tn4400 does not contribute to tetracycline resistance

Previously, we demonstrated that the Bacteroides transposon Tn4351, which confers tetracycline resistance only on aerobically grown Escherichia coli, carries a gene that codes for a tetracycline-inactivating enzyme (B. S. Speer and A. A. Salyers, J. Bacteriol. 170:1423-1429, 1988). However, Park et al. (B. H. Park, M. Hendricks, M. H. Malamy, F. P. Tally, and S. B. Levy, Antimicrob. Agents Chemother. 31:1739-1743, 1987) showed that E. coli carrying a closely related transposon, Tn4400, exhibits energy-dependent efflux of tetracycline as well as tetracycline-inactivating activity (B. H. Park and S. B. Levy, Antimicrob. Agents Chemother. 32:1797-1800, 1988). This result raised the question of whether efflux or inactivation or a combination of the two was necessary for resistance conferred by both transposons. We showed that cells carrying Tn4351 did not exhibit the clear-cut efflux activity seen with cells carrying Tn4400 but rather exhibited a tetracycline accumulation profile which could be explained solely on the basis of inactivation of tetracycline in the cytoplasm and rapid diffusion of altered tetracycline out of the cell. Additionally, we were able to clone the efflux and tetracycline-modifying genes of Tn4400 separately. The region carrying the efflux gene spanned one of the two regions in which Tn4400 differs from Tn4351. A clone containing the corresponding region of Tn4351 did not exhibit efflux. Thus, it appears that Tn4351 does not have the efflux gene and that efflux makes no contribution to the resistance conferred by Tn4351. The MIC for cells carrying the subclone from Tn4400 that contained only the gene for tetracycline inactivation was the same that for cells carrying both the inactivation and efflux genes. Cells carrying only the gene for tetracycline efflux were tetracycline sensitive. This was true even when the efflux gene was on a high-copy-number plasmid which increased the level of efflux to that associated with the Tcr gene on pBR328. These results indicate that efflux activity does not contribute significantly to the tetracycline resistance conferred by Tn4400.

The cryptic tetracycline resistance determinant on Tn4400 mediates tetracycline degradation as well as tetracycline efflux.

Escherichia coli containing the cryptic tetracycline resistance determinant (class F) from the Bacteroides fragilis transposon Tn4400 on plasmid pGAT400 expressed a detoxification of tetracycline as well as an active efflux of tetracycline. This finding concurs with the report of detoxification for a related tetracycline resistance determinant from B. fragilis on Tn4351 (B. S. Speer and A. Salyers, J. Bacteriol. 170:1423-1429, 1987), which specifies a 10-fold-higher resistance than Tn4400. Inactivation of tetracycline occurred at an initial rate of congruent to 0.7 micrograms of tetracycline per h per 10(8) cells, as determined by biologic assay and chromatographic analysis. The detoxification is a chemical degradation which can occur in the absence of energy-dependent efflux. The products of this degradation were not substrates for active transport into susceptible cells or out of pGAT400-containing E. coli. These results indicate that Tn4400 mediates two functionally different mechanisms for tetracycline resistance: an active efflux of tetracycline and a degradation of tetracycline.

Milk Inactivation of Tetracycline

Milk Inactivation of Tetracycline

Mechanisms of R Factor R931 and Chromosomal Tetracycline Resistance in Pseudomonas aeruginosa

The mechanism of tetracycline resistance mediated by R931 (a Pseudomonas aeruginosa R factor not yet successfully transferred to Escherichia coli recipients) was examined. In strain 931 (R931) (minimal inhibitory concentration [MIC] 200 mug/ml) significant tetracycline uptake did not occur until 100 mug of tetracycline per ml was included in uptake studies. The introduction of R931 into strain 280 resulted in a significant decline in (3)H-tetracycline uptake. In both strains 931 (R931) and 280 (R931), a further reduction in tetracycline uptake resulted from pre-incubation with 1 mug of tetracycline per ml. Tetracycline resistance in R(-)P. aeruginosa strains 1731, 1885, and 494, considered to be of chromosomal origin, was associated with a lack of tetracycline uptake until the MIC of the strain was obtained. No evidence of tetracycline inactivation or ribosomal resistance was detected in R(-) or R(+) strains. The MIC for R(-) strains was generally about 25 mug/ml and that for R(+) strains was 75 to 200 mug/ml.

Inactivation of Tetracycline with Cupric-Morpholine Complex

Cupric-morpholine complex degrades and inactivates tetracycline in methanol or methanol water solutions. No other agent has been reported to inactivate tetracycline so rapidly and completely at the mild conditions employed. Kanamycin is not affected. This selectivity of inactivation is used as part of a biological assay for kanamycin in the presence of tetracycline.

Inactivation of Tetracycline with Sodium Borohydride

Inactivation of Tetracycline with Sodium Borohydride