Viability PCR shows that non-ocular surfaces could contribute to transmission of Chlamydia trachomatis infection in trachoma.
Bart Versteeg, Hristina Vasileva, Joanna Houghton, Anna Last, Oumer Shafi Abdurahman, Virginia Sarah, David Macleod, Anthony W Solomon, Martin J Holland, Nicholas Thomson, Matthew J Burton
Author Information
Bart Versteeg: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Hristina Vasileva: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom.
Joanna Houghton: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Anna Last: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom.
Oumer Shafi Abdurahman: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Virginia Sarah: The Fred Hollows Foundation, London, United Kingdom.
David Macleod: Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Anthony W Solomon: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Martin J Holland: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
Nicholas Thomson: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom.
Matthew J Burton: Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom. ORCID
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. CONCLUSION: Plastic, cotton cloth and skin may contribute to transmission of the Ct strains that cause trachoma, by acting as sites where reservoirs of bacteria are deposited and later collected and transferred mechanically into previously uninfected eyes.
References
Invest Ophthalmol Vis Sci. 2003 Oct;44(10):4215-22
[PMID: 14507864]
