Viability PCR shows that non-ocular surfaces could contribute to transmission of Chlamydia trachomatis infection in trachoma

Abstract

Background The presence of Chlamydia trachomatis (Ct) DNA at non-ocular sites suggests that these sites may represent plausible routes of Ct transmission in trachoma. However, qPCR cannot discriminate between DNA from viable and non-viable bacteria. Here we use a propodium monoazide based viability PCR to investigate how long Ct remains viable at non-ocular sites under laboratory-controlled conditions. Methods Cultured Ct stocks (strain A2497) were diluted to final concentrations of 1000, 100, 10 and 1 omcB copies/μL and applied to plastic, woven mat, cotton cloth and pig skin. Swabs were then systemically collected from each surface and tested for the presence Ct DNA using qPCR. If Ct DNA was recovered, Ct viability was assessed over time by spiking multiple areas of the same surface type with the same final concentrations. Swabs were collected from each surface at 0, 2, 4, 6, 8 and 24 hours after spiking. Viability PCR was used to determine Ct viability at each timepoint. Results We were able to detect Ct DNA on all surfaces except the woven mat. Total Ct DNA remained detectable and stable over 24 hours for all concentrations applied to plastic, pig skin and cotton cloth. The amount of viable Ct decreased over time. For plastic and skin surfaces, only those where concentrations of 100 or 1000 omcB copies/μL were applied still had viable loads detectable after 24 hours. Cotton cloth showed a more rapid decrease and only those where concentrations of 1000 omcB copies/μL were applied still had viable DNA detectable after 24 hours.

Association of Chlamydia trachomatis burden with the vaginal microbiota, bacterial vaginosis, and metronidazole treatment

“…Here, we illustrated the immense spectrum of infectious chlamydial burden and even broader spectrum of total chlamydial burden in untreated infection and how IFU : GCN reveals a heterogeneity of Ct growth with some samples predominated by replicating forms, and others by non-replicating forms, supporting our previous pilot study ( Lewis et al., 2014 ). However, our future studies would benefit from the use of a recently described Ct-specific viability-PCR capable of distinguishing viable from non-viable Ct ( Janssen et al., 2016 ; Janssen et al., 2018 ; Dukers-Muijrers et al., 2020 ; Janssen et al., 2020 ; Versteeg et al., 2020 ; Janssen et al., 2022 ; Vojtech et al., 2023 ).…”

Prevalence of Trachoma after Implementation of Trachoma Elimination Interventions in Oromia Regional State, Ethiopia: Results of Impact Surveys in 131 Evaluation Units Covering 139 Districts

“…Second, clinical trials to assess novel strategies for intensified delivery of the SAFE strategy could be carried out. Research into the biology of trachoma in the region could be further investigated: routes of transmission of ocular C. trachomatis are only now being more fully explored, 2 , 4 while work on the relationship between the background conjunctival microbiome, pathogen genotype, host genotype and susceptibility to infection in different settings is in its infancy. 37–40 All of these factors could potentially contribute to persistence of disease after treatment and warrant further investigation in light of the large number of districts in Oromia where TF has not fallen below 5% after the recommended number of MDA rounds.…”

Facial cleanliness indicators by time of day: results of a cross-sectional trachoma prevalence survey in Senegal

“…Alternatively, it could be the result of parents cleaning their children’s faces before examination, as they became aware that faces were being inspected from observing the examination of other children in the central location. This could potentially have a detrimental effect, facilitating transmission if faces are wiped with unclean fomites: the detection of viable C. trachomatis DNA on non-ocular sites has demonstrated that these surfaces can contribute to ongoing transmission, and has led to suggestions that washing of plastic, hands (skin) and cloths should be considered by trachoma programmes in addition to face washing [ 2 , 28 ].…”