Biocide sensitivity of Vermamoeba vermiformis isolated from dental-unit-waterline systems

Dillon, Amanda, Achilles-Day, Undine EH, Singhrao, Simarjit Kaur orcid iconORCID: 0000-0001-9573-5963, Pearce, Mark, Morton, Leslie Hugh Glyn and Crean, Stjohn orcid iconORCID: 0000-0001-9336-8549 (2014) Biocide sensitivity of Vermamoeba vermiformis isolated from dental-unit-waterline systems. International Biodeterioration & Biodegradation, 88 . pp. 97-105. ISSN 0964-8305

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This study isolated amoebae from two different dental-unit-waterline (DUWL) sources, a simulated
laboratory system (sDUWL) and a decommissioned system (dDUWL), within 24 h of it being dismantled
from a working clinical practice. Molecular profiles of the isolates were determined and morphological
characteristics of the test organisms were examined using microscopy. DNA barcoding identified the
amoebae from both sources as being Vermamoeba vermiformis (previously described as Hartmannella
vermiformis). These amoebae have been deposited at the Culture Collection of Algae and Protozoa and as
CCAP 1534/16, GenBank accession number KC161965 (in-vitro simulated system) and CCAP 1534/17,
GenBank accession number KC188996 (decommissioned system). The organisms from both sources
exhibited two main forms: motile trophozoites and non-motile cysts. Mature cysts displayed natural
fluorescence with excitation and emission wavelength of 488 nm, attributed to the presence of natural
flavins and nicotinamide compounds. Both the encysted and the trophozoite forms of V. vermiformis
remained unaffected when exposed to the proprietary biocides tested at the concentrations recommended
for use in dental surgeries and cysts successfully excysted, to release trophozoites upon subsequent
culture. However, two out of three proprietary dental biocides tested on isolated heterotrophic
bacteria were effective at controlling bacterial contamination.

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