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MicrobiologyOpen Oct 2022Antibiotic resistance is becoming increasingly prevalent amongst bacterial pathogens and there is an urgent need to develop new types of antibiotics with novel modes of...
Antibiotic resistance is becoming increasingly prevalent amongst bacterial pathogens and there is an urgent need to develop new types of antibiotics with novel modes of action. One promising strategy is to develop resistance-breaker compounds, which inhibit resistance mechanisms and thus resensitize bacteria to existing antibiotics. In the current study, we identify bacterial DNA double-strand break repair as a promising target for the development of resistance-breaking co-therapies. We examined genetic variants of Escherichia coli that combined antibiotic-resistance determinants with DNA repair defects. We observed that defects in the double-strand break repair pathway led to significant resensitization toward five bactericidal antibiotics representing different functional classes. Effects ranged from partial to full resensitization. For ciprofloxacin and nitrofurantoin, sensitization manifested as a reduction in the minimum inhibitory concentration. For kanamycin and trimethoprim, sensitivity manifested through increased rates of killing at high antibiotic concentrations. For ampicillin, repair defects dramatically reduced antibiotic tolerance. Ciprofloxacin, nitrofurantoin, and trimethoprim induce the promutagenic SOS response. Disruption of double-strand break repair strongly dampened the induction of SOS by these antibiotics. Our findings suggest that if break-repair inhibitors can be developed they could resensitize antibiotic-resistant bacteria to multiple classes of existing antibiotics and may suppress the development of de novo antibiotic-resistance mutations.
Topics: Humans; Escherichia coli; Anti-Bacterial Agents; Escherichia coli Proteins; Nitrofurantoin; DNA Repair; Escherichia coli Infections; Ciprofloxacin; Microbial Sensitivity Tests; DNA, Bacterial; Trimethoprim
PubMed: 36314749
DOI: 10.1002/mbo3.1316 -
Journal of Chromatography. B,... May 2022The dual agent antibiotic, trimethoprim/sulfamethoxazole (TMP-SMX), has been prescribed to treat or prevent infections for over 50 years. However, there are no...
The dual agent antibiotic, trimethoprim/sulfamethoxazole (TMP-SMX), has been prescribed to treat or prevent infections for over 50 years. However, there are no published validated analytical methods for the measurement of TMP metabolites in humans. We developed methodology enabling reliable quantification of TMP and 5 metabolites in human plasma. Chromatographic separation was achieved in less than 8 min using a biphenyl column. Analytes were detected in positive electrospray mode using a tandem Waters Xevo-TQ-XS mass spectrometer. Precision and accuracy values for all analytes were within 15% of nominal values during assay validation.
Topics: Child; Chromatography, High Pressure Liquid; Humans; Plasma; Reproducibility of Results; Tandem Mass Spectrometry; Trimethoprim; Trimethoprim, Sulfamethoxazole Drug Combination
PubMed: 35428009
DOI: 10.1016/j.jchromb.2022.123232 -
International Journal of Molecular... Apr 2021Eighteen previously undescribed trimethoprim (TMP) analogs containing amide bonds () were synthesized and compared with TMP, methotrexate (MTX), and netropsin (NT).... (Comparative Study)
Comparative Study
Synthesis, Biological Activity, and Molecular Dynamics Study of Novel Series of a Trimethoprim Analogs as Multi-Targeted Compounds: Dihydrofolate Reductase (DHFR) Inhibitors and DNA-Binding Agents.
Eighteen previously undescribed trimethoprim (TMP) analogs containing amide bonds () were synthesized and compared with TMP, methotrexate (MTX), and netropsin (NT). These compounds were designed as potential minor groove binding agents (MGBAs) and inhibitors of human dihydrofolate reductase (DHFR). The all-new derivatives were obtained via solid phase synthesis using 4-nitrophenyl Wang resin. Data from the ethidium displacement test confirmed their DNA-binding capacity. Compounds (49.89% and 43.85%) and (41.68% and 42.99%) showed a higher binding affinity to pBR322 plasmid than NT. The possibility of binding in a minor groove as well as determination of association constants were performed using calf thymus DNA, T4 coliphage DNA, poly (dA-dT), and poly (dG-dC). With the exception of compounds (IC50 = 56.05 µM) and (IC50 = 55.32 µM), all of the compounds showed better inhibitory properties against DHFR than standard, which confirms that the addition of the amide bond into the TMP structures increases affinity towards DHFR. Derivatives , , , , and were found to be the most potent DHFR inhibitors. This molecular modelling study shows that they interact strongly with a catalytically important residue Glu-30.
Topics: Folic Acid Antagonists; Molecular Docking Simulation; Molecular Dynamics Simulation; Trimethoprim
PubMed: 33916202
DOI: 10.3390/ijms22073685 -
Antimicrobial Agents and Chemotherapy May 1978Sulfamethoxazole-trimethoprim and three oral cephalosporins, cefaclor, cephalexin, and cephradine, were evaluated in vitro as possible alternatives to chloramphenicol in...
Sulfamethoxazole-trimethoprim and three oral cephalosporins, cefaclor, cephalexin, and cephradine, were evaluated in vitro as possible alternatives to chloramphenicol in the treatment of non-central nervous system infections due to ampicillin-resistant Haemophilus influenzae. Sixty-four isolates of H. influenzae, including 31 beta-lactamase-positive strains, were tested by the agar dilution method. All strains were inhibited by 0.78/0.039 mug sulfamethoxazole-trimethoprim per ml and by 0.78 mug of chloramphenicol per ml. At 6.25 mug/ml, 100, 11, and 3% of all strains were inhibited by cefaclor, cephalexin, and cephradine, respectively. Thus, on the basis of drug concentrations presumably achievable in serum, 100% of strains were susceptible to sulfamethoxazole-trimethoprim, chloramphenicol, and cefaclor. However, a considerable inoculum effect was noted with both beta-lactamase-positive and -negative strains, when tested with sulfamethoxazole-trimethoprim; the minimal inhibitory concentrations of cefaclor were only slightly affected. Also, synergistic effects of sulfamethoxazole-trimethoprim, sulfamethoxazole-erythromycin, and sulfamethoxazole-cefaclor were seen when combinations were tested against both beta-lactamase-positive and -negative strains, as determined by minimal inhibitory concentrations measured by the broth dilution method and by killing curve analyses. These results support further evaluation of these combinations and of cefaclor alone for the treatment of non-central nervous system infections due to H. influenzae.
Topics: Cephalosporins; Cephradine; Drug Combinations; Drug Synergism; Haemophilus influenzae; Microbial Sensitivity Tests; Sulfamethoxazole; Trimethoprim
PubMed: 307367
DOI: 10.1128/AAC.13.5.861 -
The ISME Journal Sep 2023Trimethoprim (TMP) is a low-cost, widely prescribed antibiotic. Its effectiveness is increasingly challenged by the spread of genes coding for TMP-resistant...
Trimethoprim (TMP) is a low-cost, widely prescribed antibiotic. Its effectiveness is increasingly challenged by the spread of genes coding for TMP-resistant dihydrofolate reductases: dfrA, and the lesser-known, evolutionarily unrelated dfrB. Despite recent reports of novel variants conferring high level TMP resistance (dfrB10 to dfrB21), the prevalence of dfrB is still unknown due to underreporting, heterogeneity of the analyzed genetic material in terms of isolation sources, and limited bioinformatic processing. In this study, we explored a coherent set of shotgun metagenomic sequences to quantitatively estimate the abundance of dfrB gene variants in aquatic environments. Specifically, we scanned sequences originating from influents and effluents of municipal sewage treatment plants as well as river-borne microbiomes. Our analyses reveal an increased prevalence of dfrB1, dfrB2, dfrB3, dfrB4, dfrB5, and dfrB7 in wastewater microbiomes as compared to freshwater. These gene variants were frequently found in genomic neighborship with other resistance genes, transposable elements, and integrons, indicating their mobility. By contrast, the relative abundances of the more recently discovered variants dfrB9, dfrB10, and dfrB13 were significantly higher in freshwater than in wastewater microbiomes. Moreover, their direct neighborship with other resistance genes or markers of mobile genetic elements was significantly less likely. Our findings suggest that natural freshwater communities form a major reservoir of the recently discovered dfrB gene variants. Their proliferation and mobilization in response to the exposure of freshwater communities to selective TMP concentrations may promote the prevalence of high-level TMP resistance and thus limit the future effectiveness of antimicrobial therapies.
Topics: Trimethoprim Resistance; Wastewater; Genes, Bacterial; Trimethoprim; Anti-Bacterial Agents
PubMed: 37369703
DOI: 10.1038/s41396-023-01460-7 -
PLoS Computational Biology Feb 2022Antimicrobial resistance presents a significant health care crisis. The mutation F98Y in Staphylococcus aureus dihydrofolate reductase (SaDHFR) confers resistance to the...
Antimicrobial resistance presents a significant health care crisis. The mutation F98Y in Staphylococcus aureus dihydrofolate reductase (SaDHFR) confers resistance to the clinically important antifolate trimethoprim (TMP). Propargyl-linked antifolates (PLAs), next generation DHFR inhibitors, are much more resilient than TMP against this F98Y variant, yet this F98Y substitution still reduces efficacy of these agents. Surprisingly, differences in the enantiomeric configuration at the stereogenic center of PLAs influence the isomeric state of the NADPH cofactor. To understand the molecular basis of F98Y-mediated resistance and how PLAs' inhibition drives NADPH isomeric states, we used protein design algorithms in the osprey protein design software suite to analyze a comprehensive suite of structural, biophysical, biochemical, and computational data. Here, we present a model showing how F98Y SaDHFR exploits a different anomeric configuration of NADPH to evade certain PLAs' inhibition, while other PLAs remain unaffected by this resistance mechanism.
Topics: Drug Resistance, Bacterial; Folic Acid Antagonists; Humans; NADP; Staphylococcal Infections; Staphylococcus aureus; Tetrahydrofolate Dehydrogenase; Trimethoprim
PubMed: 35143481
DOI: 10.1371/journal.pcbi.1009855 -
Antimicrobial Agents and Chemotherapy Sep 1977The in vitro effect of trimethoprim on the inhibitory and bactericidal activity of amikacin against 20 strains each of Klebsiella pneumoniae and Serratia marcescens, 15...
The in vitro effect of trimethoprim on the inhibitory and bactericidal activity of amikacin against 20 strains each of Klebsiella pneumoniae and Serratia marcescens, 15 strains of Escherichia coli, and 10 strains of Pseudomonas aeruginosa was examined by the checkerboard technique in microtiter plates. Trimethoprim had a synergistic effect on the inhibitory and bactericidal activity of amikacin against the majority of non-pseudomonas strains tested. The mean +/- standard deviation fractional inhibitory concentration indexes were 0.59 +/- 0.19 for the Klebsiella strains, 0.48 +/- 0.18 for the Serratia strains, and 0.60 +/- 0.22 for the E. coli strains tested. Respective mean +/- standard deviation fractional bactericidal concentration indexes for these organisms were 0.55 +/- 0.17, 0.54 +/- 0.29, and 0.61 +/- 0.22. A total of 40% of the Klebsiella strains, 80% of the Serratia strains, and 46% of the E. coli strains had a fractional inhibitory concentration equal to or less than 0.25 for both of these antimicrobial agents and were considered to be synergistically inhibited by the combination. By applying this criterion to bactericidal activity, synergy was demonstrated against 50, 65, and 46% of these strains, respectively. All of the Enterobacteriaceae tested were inhibited by clinically achievable concentrations of trimethoprim and amikacin. Antagonism was not demonstrated with any of the organisms tested. Trimethoprim had no antibacterial effect on the Pseudomonas strains and did not alter amikacin's activity against these bacteria.
Topics: Amikacin; Drug Synergism; Escherichia coli; Kanamycin; Klebsiella pneumoniae; Pseudomonas aeruginosa; Serratia marcescens; Species Specificity; Trimethoprim
PubMed: 410362
DOI: 10.1128/AAC.12.3.349 -
Postgraduate Medical Journal May 1992
Topics: Aged; Aged, 80 and over; Female; Humans; Skin Diseases; Trimethoprim; Vasculitis
PubMed: 1630995
DOI: 10.1136/pgmj.68.799.391 -
American Journal of Ophthalmology Oct 1990
Topics: Female; Humans; Middle Aged; Necrosis; Nocardia Infections; Sclera; Scleritis; Sulfamethoxazole; Trimethoprim
PubMed: 2220994
DOI: 10.1016/s0002-9394(14)77042-4 -
Antimicrobial Agents and Chemotherapy Dec 1984The pharmacokinetics of trimethoprim (TMP) and sulfamethoxazole (SMX) in cerebrospinal fluid (CSF) and serum after a single intravenous infusion of 5 mg of TMP and 25 mg...
The pharmacokinetics of trimethoprim (TMP) and sulfamethoxazole (SMX) in cerebrospinal fluid (CSF) and serum after a single intravenous infusion of 5 mg of TMP and 25 mg of SMX per kg of body weight over approximately 120 min were studied i nine patients who had uninflamed meninges and were undergoing elective myelography. Peak concentrations of TMP and SMX in CSF were 1 microgram/ml and 13.8 micrograms/ml, respectively. The peak TMP concentration in CSF occurred significantly earlier than the peak SMX concentration (60 versus 480 min postinfusion). At 15 h, there was no detectable TMP in the CSF, and there was 4.7 micrograms of SMX per ml of CSF. In the postdistribution phase (in CSF), simultaneous CSF-to-serum concentration ratios ranged from 0.23 to 0.53 for TMP and from 0.20 to 0.36 for SMX. CSF penetration (measured by comparison of the area under the curve of the composite CSF and serum concentration-time curves) was 18% for TMP and 12% for SMX. A loading dose of TMP-SMX (bases on TMP) of 10 to 12 mg/kg and a maintenance dose of 6 mg/kg every 8 h or 8 mg/kg every 12 h (with a 2-h infusion) should yield steady-state peak concentrations of at least 5 micrograms of TMP per ml of serum and 160 micrograms of SMX per ml of serum. Further studies of TMP-SMX administered in these doses in the treatment of serious bacterial infection, including meningitis, are warranted.
Topics: Adult; Aged; Drug Combinations; Female; Humans; Kinetics; Male; Meninges; Middle Aged; Sulfamethoxazole; Time Factors; Trimethoprim; Trimethoprim, Sulfamethoxazole Drug Combination
PubMed: 6335381
DOI: 10.1128/AAC.26.6.811