Utility of Antimicrobial Susceptibility Testing in Trichomonas vaginalis–Infected Women With Clinical Treatment Failure

Abstract

Clinical and microbiologic cure rates were higher for women who were treated in accordance with the recommendation provided after in vitro testing compared with those who received a lower dose or a different drug. Susceptibility testing leading to tailored treatment may have a beneficial role for management of women with persistent trichomoniasis.

Trichomonas vaginalis Metronidazole Resistance Is Associated with Single Nucleotide Polymorphisms in the Nitroreductase Genes ntr4 Tv and ntr6 Tv

“…For example, one study linked resistance to infection of T. vaginalis by Mycoplasma (16); however, the mechanism by which infection would impart resistance is unclear, and this association was not found in a subsequent study (17). Another study found that infection by a double-stranded RNA virus was associated with a lower mean metronidazole MLC value (2); however, the virus is also strongly associated with population 1, being present in 73% of isolates in this population compared to only 2.5% of isolates in population 2 (18). Further studies will be required to determine the relative contribution of population ancestry, ntr Tv genotype, and other factors to metronidazole resistance.…”

Comparative aspects of immunity and vaccination in human and bovine trichomoniasis: a review

“…There are reports of dysuria, lower abdominal discomfort, itchiness of the vagina, leucorrhea, and vaginal odor in some women (Schwebke and Burgess 2004). Thus, Trichomonas vaginalis infection is usually only detected during routine STD screening (Bosserman et al 2011).…”

United Kingdom National Guideline on the Management of Trichomonas vaginalis 2014

“…Clinical and microbiological cure rates were higher in women with previous treatment failure who were treated in accordance with a treatment protocol utilising the results of a resistance test. 72 Resistance data from the UK are lacking due to the absence of a metronidazole resistance testing service; however in 2002, one group found a 3.5% prevalence of non-response to standard dose metronidazole in the absence of re-infection and nonadherence. 73 Clinical isolates resistant to metronidazole can be resistant to tinidazole but usually with significantly lower minimal lethal concentrations to tinidazole than metronidazole.…”

“…Paromomycin* intravaginally 250 mg once or twice daily for 14 days -56-58% cure rate reported 78,80 Furazolidone* intravaginally 100 mg twice daily for 12-14 days -33% cure rate reported 72,81 Acetarsol* pessaries 500 mg nocte for 2 weeks 6% Nonoxynol-9* pessaries nightly for 2 weeks Availability *The medicines suggested for use in treatment failure are unlicensed products and may not be readily available for purchase in the UK. The pharmacy purchasing department may be able to source some of these products from specialist manufacturers.…”

“…72 If resistance testing is not available, high-dose tinidazole regimens are recommended, as in the above study 65% of women with clinical treatment failure did not have tinidazole-resistant isolates and 83% of those receiving the recommended high-dose treatment were cured compared with 57% of women receiving a lower-than-recommended dose. If very high-dose tinidazole has been unsuccessful it is difficult to recommend one specific further treatment.…”