Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

Abstract

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Keywords: Cumitech 13; endophthalmitis; eye infection; keratitis; ocular infection; retinitis; uveitis.

FIG 1

Anatomy of the eye and surrounding tissues. (Licensed from https://www.carlsonstockart.com/photo/human-eye-anatomy-illustration-1/.)

FIG 2

(A to C) Gram staining of cornea tissue infected with pathogens requiring rapid medical intervention. (A) Neisseria gonorrhoeae; (B) Bacillus cereus (note the iris melanin granules [reprinted from reference 394]); (C) hyaline septate mold (scopulariopsis). (D) Papanicolaou stain of HSV infection in the cornea.

FIG 3

Gram (A)- and hematoxylin and eosin (H&E) (B)-stained sections of cornea tissue with melanized granules from the iris mimicking bacterial cocci. Note the brownish pigmentation, irregular edges to some of the granules, and the lack of an appropriate host response.

FIG 4

Calcofluor white-stained cornea scraping (A) and H&E-stained section (B) of cornea tissue showing Acanthamoeba cysts in a patient with contact lens-associated keratitis.