Diagnostic Yield of Corneal, Contact Lens, and Lens Fluid Cultures in Microbial Keratitis: A 12-Year Single-Center Study

Purpose: – To determine the yield of culturing contact lenses (CL) and contact lens fluid/cases (CLF) to isolate recognized pathogens in suspected microbial keratitis (MK).Methods: – Data from 4298 ocular samples of MK collected at the Royal Liverpool University Hospital between January 2012 and December 2023 were reviewed. The isolation rates and proportion of recognized pathogens were compared between corneal impression membranes (CIM) and scrapes (CS), CL, and CLF. Chi-square tests and mixed-effects logistic models were used to assess differences in distribution among all isolates and subgroups of samples.Results: – The overall isolation rate was 54.1%, with CL having the highest rate ([348/466], 74.7%), followed by CIM ([1822/2940], 62%), CS ([126/566], 22.3%), and CLF ([23/317], 7.3%). CLF, however, had the highest proportion of recognized pathogens ([22/28], 78.6%), followed by CL ([269/531], 50.7%), CS ([71/142], 50%), and CIM ([728/2218], 32.8%). CIM and CS predominantly detected Gram-positive bacteria, whereas CLF had the highest rates of Acanthamoeba ([13/28], 46.4%) and fungal isolates ([4/28], 14.3%). CL and/or CLF cultures led to altered treatment in 10.5% of cases.Conclusions: – In suspected MK, culturing the CLF and CL can increase the probability of detecting a recognized pathogen that in turn may help guide treatment.