Detection of metronidazole resistance in Trichomonas vaginalis using uncultured vaginal swabs

Bongekile Ngobese; Ravesh Singh; Khine Swe Swe- Han; Partson Tinarwo; Nonkululeko Mabaso; Nathlee S Abbai

doi:10.1007/s00436-022-07548-x

Detection of metronidazole resistance in Trichomonas vaginalis using uncultured vaginal swabs

Parasitol Res. 2022 Aug;121(8):2421-2432. doi: 10.1007/s00436-022-07548-x. Epub 2022 Jun 3.

Authors

Bongekile Ngobese¹, Ravesh Singh^{2

3}, Khine Swe Swe- Han^{2

3}, Partson Tinarwo⁴, Nonkululeko Mabaso⁵, Nathlee S Abbai⁵

Affiliations

¹ School of Clinical Medicine Laboratory, College of Health Science, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa. bongeeeh@gmail.com.
² Department of Medical Microbiology, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa.
³ Department of Microbiology, National Health Laboratory Services, KwaZulu-Natal Academic Complex, Inkosi Albert Luthuli Central Hospital, Durban, South Africa.
⁴ Department of Biostatistics, College of Health Sciences, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa.
⁵ School of Clinical Medicine Laboratory, College of Health Science, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa.

PMID: 35657426
DOI: 10.1007/s00436-022-07548-x

Abstract

Trichomonas vaginalis (T. vaginalis) is the most prevalent sexually transmitted infection (STI) globally. Metronidazole is the drug of choice for treating T. vaginalis infections although metronidazole-resistant T. vaginalis has been reported in clinical isolates. The purpose of this study was to determine the presence of mutations in nitroreductase genes associated with metronidazole resistance in vaginal swabs testing positive for T. vaginalis. This study included 385 human immunodeficiency virus (HIV)-positive pregnant women. Vaginal swabs were collected from consenting pregnant women and used for the detection of T. vaginalis using the TaqMan assay. From the vaginal swabs, nitroreductase genes ntr4 and ntr6 containing mutations associated with metronidazole resistance were amplified using a quantitative polymerase chain reaction (PCR) assay. To validate the PCR assay, T. vaginalis cultured isolates with known metronidazole resistance profiles were used as controls in the mutation detection assays. The prevalence of T. vaginalis in the study population was 12.2% (47/385). Mutations associated with resistance to metronidazole were detected in more than 40% of the samples tested, i.e. 21/47 (45%) and 24/47 (51%) for ntr4 and ntr6, respectively. A total of 19 samples (40%) carried mutations for both ntr4 and ntr6 genes associated with metronidazole resistance. The validation assays showed a positive correlation between phenotypic and genotypic resistance profiles. This study found a high prevalence of mutations associated with metronidazole resistance. This is concerning since metronidazole is currently used in the syndromic management of STIs in South Africa. Molecular-based assays for monitoring metronidazole resistance profiles using nitroreductase genes may serve as a feasible method for antimicrobial surveillance studies for T. vaginalis.

Keywords: HIV; Metronidazole resistance; Pregnancy; South Africa; Trichomonas vaginalis.

MeSH terms

Drug Resistance
Female
Humans
Metronidazole / pharmacology
Metronidazole / therapeutic use
Polymerase Chain Reaction
Pregnancy
Trichomonas Infections* / drug therapy
Trichomonas Vaginitis* / diagnosis
Trichomonas vaginalis*

Substances

Metronidazole