The Corneal Ulcer One-Touch Study: A Simplified Microbiological Specimen Collection Method

• Published in: American journal of ophthalmology 2015-01, Vol.159 (1), p.37-43.e1
• Main Authors: Pakzad-Vaezi, Kaivon, Levasseur, Steve D, Schendel, Steven, Mark, Sean, Mathias, Richard, Roscoe, Diane, Holland, Simon P
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Antibiotics; Bacteria - isolation & purification; Bacteriological Techniques; Colleges & universities; Confidence intervals; Corneal Ulcer - microbiology; Eye Infections, Bacterial - microbiology; Eye Infections, Fungal - microbiology; Female; Humans; Laboratories; Male; Medical personnel; Methods; Middle Aged; Ophthalmology; Patients; Prospective Studies; Sensitivity and Specificity; Specimen Handling - methods; Streptococcus infections; Ulcers; Young Adult
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/j.ajo.2014.09.021

Purpose To determine if a new, single-sample device (ESwab; Copan Diagnostics, Inc) can simplify the traditional multi-sample approach to specimen collection in infectious keratitis. Design Prospective, diagnostic test evaluation. Methods In this institutional study, patients with suspected infectious keratitis meeting traditional criteria for diagnostic corneal specimen collection and culture were randomized to the order of first specimen collection method: ESwab or a sample directly plated for growth on chocolate agar. This was followed by standard samples for blood agar, Gram stain, Sabouraud agar, thioglycolate broth, and brain heart infusion broth in all cases. The specimens collected using the 2 approaches were analyzed separately by the laboratory in a masked fashion. The main outcome measure was positive growth on cultured media. Results Eighty-one eyes from 80 consecutive patients were sampled. Culture positivity rate for the multi-sample method and ESwab was 70% and 69%, respectively, with a 75% agreement rate. ESwab sensitivity was 84% (95% confidence interval [CI]: 72%–93%), with a specificity of 67% (95% CI: 45%–84%). Positive and negative predictive values of the ESwab were 86% (95% CI: 74%–94%) and 64% (95% CI: 43%–82%), respectively. There was no difference in positive culture reports with respect to the order of specimen collection technique used. Conclusions The single-sample ESwab method is a more accessible and less cumbersome approach to corneal culturing for ophthalmologists, particularly those in the community setting who do not have access to the full set of traditional culture materials. Culture results using this single-sample approach were comparable to the multi-sample method.