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Ananya Datta, Mark D P Willcox, Fiona Stapleton; Bacterial coaggregation and cohesion among the isolates from contact lens cases. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1777. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Microbial contamination of contact lens cases often occurs during lens wear. Bacterial colonization of surfaces involves several stages including adhesion, coaggregation, cohesion, micro-colony formation, maturation and eventual dispersal. The aim of this study was to examine cohesion, coaggregation and co-culture between bacteria commonly isolated from contact lens cases.
Staphylococcus epidermidis, Staphylococcus haemolyticus, Micrococcus luteus and Acinetobacter radioresistens (two strains each) isolated from contact lens cases of two asymptomatic wearers were used in this study. In the cohesion assay, bacteria were grown, washed and examined by incubating lens cases with two different types of bacteria sequentially and assessing the number of adhered cells of each isolate. The ability of isolates to interfere with the growth of other isolates was tested by growing strains in co-cultures for 24 hrs and determining the numbers of cells of individual strains. For coaggregation, equal proportions of two bacterial suspensions were mixed and allowed to coaggregate for 24 hrs. Inhibition of coaggregation was tested by the addition of lactose (0.06 M) or sucrose (0.06 M) or pronase.
The initial adhesion of M. luteus or A. radioresistens significantly (p<0.05) enhanced the subsequent adhesion of the staphylococci. The addition of A. radioresistens in liquid media significantly (p<0.05) enhanced the growth of staphylococci. S. epidermidis or S. haemolyticus coaggregated with M. luteus or A. radioresistens. The degree of coaggregation varied between 30% to 54%. The highest coaggregation (54% ± 5) was seen between A. radioresistens 22-1 and S. epidermidis 22-1, isolated from the same lens case. Only lactose or sucrose treatment of staphylococci could partly inhibit coaggregation of some pairs.
Coaggregation, cohesion and growth promotion may facilitate the process of bacterial colonisation in contact lens cases during use. Thus, it may help to design a better approach to prevent the biofilm formation in lens cases by targeting the specific bacteria. This may in turn reduce contact lens induced ocular adverse events.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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