Detection of metronidazole resistance in Trichomonas vaginalis using uncultured vaginal swabs

High frequency of point mutations in the nitroreductase 4 and 6 genes of Trichomonas vaginalis associated with metronidazole resistance

Trichomoniasis, a globally distributed sexually transmitted infection, is caused by the urogenital parasite Trichomonas vaginalis Donné, 1836 affecting both women and men. The treatment of choice is metronidazole (MTZ). In the present study, 15 samples of vaginal discharge and urine were analysed by sequencing nitroreductase genes (ntr4 and ntr6). An in silico model was structured to illustrate the location of point mutations (PM) in the protein. The ntr4 gene presented four PMs: G76C (10/10), C213G (9/10), C318A (5/10) and G424A (1/10), while the ntr6 gene had eight PMs; G593A (13/13) the most frequent, G72T and G627C, both in 8/13. The PM C213G and A438T generated a stop codon causing a truncated nitroreductase 4 and 6 protein. Docking analysis demonstrated that some models had a decrease in binding affinity to MTZ (p < 0.0001). A high frequency of mutations was observed in the samples analysed that could be associated with resistance to MTZ in Chile.

A novel fluorescent traceable carbon quantum dots with selective antibacterial activity against Porphyromonas gingivalis

Antibiotics can kill bacteria, but their continued use can easily lead to drug resistance, particularly the main pathogenic bacteria of periodontitis, Porphyromonas gingivalis. However, to avoid drug resistance, carbon quantum dots (CDs) have great potential as a bioactive material in antimicrobial therapy. Herein, we use ornidazole as raw material to prepare CDs of different sizes by microwave irradiation and screen CDs with fluorescence and bacteriostatic properties. The inhibition experiments and live/dead assays of P. gingivalis exhibited outstanding antibacterial effects. This research aimed to develop nano-level antibacterial active materials that also have fluorescence traceability. This study offers a different method for the development of multifunctional CDs, provides valuable strategies for the treatment of diseases associated with P. gingivalis, and predicts great application prospects in the field of biomedicine.

A fluorescence-based assay for Trichomonas vaginalis drug screening

BACKGROUND

The emergence and spread of drug resistance in Trichomonas vaginalis parasites has become an important concern in trichomoniasis treatment. Fast and reliable growth assessment is critical for validating in vitro drug susceptibility and high-throughput screening of newly developed drugs.

METHODS

Modified media without yeast extract were evaluated for their ability to support the growth of T. vaginalis parasites. The potential of the nucleic acid-binding dye SYBR Green I for detecting T. vaginalis drug resistance was characterized, and seeding parasite concentration and incubation time were optimized. The fluorescence assay based on SYBR Green I was further validated in four T. vaginalis isolates with different susceptibilities to the antibiotics metronidazole, tinidazole, ornidazole and secnidazole, and compared with the traditional method that detects minimum lethal concentrations (MLCs).

RESULTS

A modified medium consisting of RPMI 1640 and Tryptone Plus as replacements for yeast extract and tryptone, respectively, in traditional trypticase-yeast extract-maltose (TYM) medium exhibited similar performance as TYM medium in maintaining T. vaginalis growth, while it showed much lower background fluorescent signals. The T. vaginalis SYBR Green I-based fluorescence (TSF) drug assay was found to have to satisfy one of two conditions to demonstrate the 50% inhibitory concentration of metronidazole for the sensitive isolate TV-334: (i) a seeding density of 3 × 104 parasites/ml and an incubation time of 48 h; or (ii) a seeding density of 1 × 104 parasites/ml and an incubation time of 72 h. Subsequent validation experiments revealed that the 48-h incubation/3 × 104 parasites/ml seeding density condition had a greater sensitivity to detect drug resistance than the 72-h condition. The TSF assay also exhibited high efficiency in identifying parasite drug resistance, as evidenced by its strong correlation with the standard MLC assay results (P = 0.003).

CONCLUSIONS

This study presents a robust TSF assay that has the potential to facilitate high-throughput, automated in vitro anti-trichomoniasis susceptibility testing for drug resistance monitoring and drug development. In comparison to the standard MLC method, this assay offers the advantages of reduced labor and elimination of subjective examination.