Microbial Landscape in Herpetic Keratitis in Patients with Coronavirus Infection

The manifestation of herpetic keratitis is influenced by a variety of pathological factors. Coronavirus infection is both a precipitating and triggering factor for ophthalmic herpes, both in the acute phase of the disease and in post-COVID syndrome. Given the combined attack on the immune system by the coronavirus itself, herpes viruses, and iatrogenic immunosuppression, is difficult to overestimate the pathological role of secondary bacterial infection. The aim of this study is a retrospective analysis the results of microbial associations in conjunctival and nasopharyngeal swabs in patients with complicated ophthalmic herpes following coronavirus pneumonia. 

Material and methods. The retrospective analysis included 11 patients with various forms of herpetic keratitis with ulceration (recurrent/sluggish flow), which developed late after severe coronavirus pneumonia. All patients underwent a standard ophthalmic examination and were questioned about the presence of trigger factors and comorbid conditions. Microbiological samples from the conjunctiva and nasopharynx were cultured on solid nutrient media. Colony growth was quantified in colony-forming units (CFU/ml) per 1.0 ml of biological material using standard grading methods. Identified pathogens were tested for sensitivity to the main groups of antibacterial drugs using the disk method. Results: In only one case, conjunctival culture yielded two pathogenic cultures — Staphylococcus aureus and Moraxella catarrhalis — at 104–106 CFU/ml. The results of nasopharyngeal culture on nutrient media turned out to be informative with respect to the dominant pathogens. Among the nasopharyngeal culture results (25 cultures), the leading ones were Staphylococcus aureus (10 cases, 40 %) and Streptococcus pneumoniae (7 cases, 28 %). Less frequently, the growth of cultures of such pathogens as Klebsiella pneumoniae (4 cases, 16 %), Escherichia coli (8 %), Moraxella catarrhalis and Hemophilus influenzae (4 % each) was determined. When determining the sensitivity to groups of antibiotics, the microflora showed high sensitivity to fluoroquinolones (15 samples, 60 % of cases), mainly moderate sensitivity was determined to macrolides and aminoglycosides (15 and 14 samples, respectively). Moderate sensitivity was determined to penicillins (19 samples), and the highest proportion of resistance was found to cephalosporins. 

Conclusion. The high sensitivity of the isolated microflora to fluoroquinolones indicates their use in the treatment of complicated forms of herpetic keratitis with activation of polybacterial flora. One of the possible drugs of choice is besifloxacin, which is not used systemically and has minimal risks of potential resistance of microbial associations to it. A comprehensive treatment approach, including thorough laboratory testing and consultation with related specialists (otolaryngologist and immunologist), is crucial for achieving recovery in the development of protracted forms of ophthalmic herpes associated with chronic inflammatory diseases of the nasopharynx.

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