Clinical Characterization and Outcomes of Culture- and Polymerase Chain Reaction-Negative Cases of Infectious Keratitis.

PURPOSE: To examine the clinical presentation, management, and outcomes of culture and polymerase chain reaction (PCR) negative cases of infectious keratitis. METHODS: In this retrospective case series, we evaluated the laboratory and medical records of culture- and PCR-negative cases (2016-2020) reported to a tertiary care center, which were presumed to be infectious keratitis on the basis of clinical history and presentation. RESULTS: A total of 121 cases with culture-negative keratitis were included in this study. The mean age of the patients was 48.42 ± 1.89 years, and 53.72% were female. At presentation, the presumed etiology was viral in 38.01%, bacterial in 27.27%, fungal in 8.26%, Acanthamoeba in 6.61%, and unlisted in 28.92% of cases. The most common risk factors were a previous history of ocular surface diseases (96.69%) and contact lens use (37.19%). In total, 61.98% of the patients were already on antimicrobial medication at presentation. The initial management was altered in 79 cases (65.29%) during the treatment course. Average presenting and final (post-treatment) visual acuities (VA) were 0.98 ± 0.04 (LogMAR) and 0.42 ± 0.03 (LogMAR), respectively. A significantly higher frequency of patients with a final VA worse than 20/40 (Snellen) had worse VA at initial presentation (p < 0.0001). A history of ocular surface disease, cold sores, and recurrent infection (p < 0.05) were more commonly associated with a presumed diagnosis of viral keratitis. The patients with presumed bacterial etiology were younger and had a history of poor contact lens hygiene (p < 0.05). CONCLUSIONS: We observed a distinct difference in clinical features among patients with culture-negative and PCR-negative keratitis managed for presumed viral and bacterial infections. Although there was significant variability in presentation and management duration in this cohort, the visual outcomes were generally favorable.

Anti-Infective Treatment and Resistance Is Rarely Problematic with Eye Infections.

The treatment of eye infections is very different than treating other body infections that require systemic anti-infectives. Endophthalmitis, keratitis, conjunctivitis, and other ocular infections are treated with direct injection and with topical drops directly to the infection site. There are no anti-infective susceptibility standards to interpret treatment success, but the systemic standards can be used to guide ocular therapy if the concentration of anti-infective in the ocular tissue is assumed to be higher than the concentration in the blood serum. This Perspective describes: (1) eye infections, (2) diagnostics of eye infections, (3) anti-infective treatment of eye infections, (4) anti-infective resistance of ocular pathogens, and (5) alternative anti-infective delivery and therapy. The data, based on years of clinical and laboratory research, support the premise that ocular infections are less problematic if etiologic agents are laboratory-diagnosed and if prompt, potent, anti-infective therapy is applied. Anti-infective susceptibility should be monitored to assure continued therapeutic success and the possibility of new-found resistance. New delivery systems and therapies may be helpful to better treat future ocular infections.

Insect Fungus Metarhizium robertsii Is a Rare Causative Agent of Keratitis.

PURPOSE: This study aimed to describe a case of keratitis secondary to Metarhizium robertsii, a soil-dwelling fungus with typical insect pathogenicity. METHODS: A Case report. RESULTS: A 58-year-old man with a ocular history of soft contact lens overwear, poor contact lens hygiene, and ocular exposure to ground well water supplying his house was referred to our university practice for a central corneal ulcer with 40% thinning. Same-day rapid microscopic detection with Giemsa stain identified the presence of many hyphae elements, and he was ultimately diagnosed with M. robertsii keratitis. The patient's course involved severe and progressive corneal thinning that stabilized over a 3-month course of antifungal therapy. CONCLUSIONS: Metarhizium robertsii seems more aggressive than other forms of fungal keratitis; therefore, this infection may be watched more closely with the risk for quick progressive corneal thinning, even while on antifungal management.

Speciation and Antibiotic Susceptibilities of Coagulase Negative Staphylococci Isolated from Ocular Infections.

Coagulase-negative staphylococci (CoNS) are frequently occurring ocular opportunistic pathogens that are not easily identifiable to the species level. The goal of this study was to speciate CoNS and document antibiotic susceptibilities from cases of endophthalmitis (n = 50), keratitis (n = 50), and conjunctivitis/blepharitis (n = 50) for empiric therapy. All 150 isolates of CoNS were speciated using (1) API Staph (biochemical system), (2) Biolog GEN III Microplates (phenotypic substrate system), and (3) DNA sequencing of the sodA gene. Disk diffusion antibiotic susceptibilities for topical and intravitreal treatment were determined based on serum standards. CoNS identification to the species level by all three methods indicated that S. epidermidis was the predominant species of CoNS isolated from cases of endophthalmitis (84-90%), keratitis (80-86%), and conjunctivitis/blepharitis (62-68%). Identifications indicated different distributions of CoNS species among endophthalmitis (6), keratitis (10), and conjunctivitis/blepharitis (13). Antibiotic susceptibility profiles support empiric treatment of endophthalmitis with vancomycin, and keratitis treatment with cefazolin or vancomycin. There was no clear antibiotic choice for conjunctivitis/blepharitis. S. epidermidis was the most frequently found CoNS ocular pathogen, and infection by other CoNS appears to be less specific and random. Antibiotic resistance does not appear to be a serious problem associated with CoNS.

An 18-Year Overview of Serratia marcescens Ocular Infection.

PURPOSE: Serratia marcescens is a frequent ocular bacterial pathogen implicated in keratitis, endophthalmitis, and conjunctivitis. We evaluated the risk factors and treatment outcomes of ocular infections due to S. marcescens. METHODS: In this retrospective observational study, all S. marcescens-positive cases between February 2002 and February 2020 were reviewed for ocular risk factors that included log of minimal angle of resolution visual acuity (VA), medical management, and time to epithelial defect closure. RESULTS: Fifty-one patients were identified (72.5% females, 46.8±23.3 years). Forty-six patients had complete medical records, and 5 had microbiology data available. The most prevalent ocular risk factors were, contact lens (CL) use (68.6%), corneal disease (52.9%), and history of ocular surgery (41.2%). Mean presenting VA was 1.3±1.0. About half of the patients presented with a central ulcer (49%, 25), large infiltrate (20.4±31.8 mm2 mean), and hypopyon (43.1%, 22). All cases were reported to be susceptible to ciprofloxacin. Defect closure occurred in 52.3±117.1 days and final VA was 0.86±0.88. Adjunctive treatments were required in 14 cases (27.5%). One patient underwent surgical intervention. Features associated with poor VA outcomes included, history of glaucoma (P=0.038), older age at presentation (P<0.001), presence of hypopyon (0.045), poor VA at presentation (0.0086), time to epithelial defect closure (0.0196), and large infiltrate size (P=0.0345). CONCLUSIONS: S. marcescens keratitis and conjunctivitis is associated with CL use and history of ocular surface disease. Worse outcomes were associated with older age, infiltrate size, presence of hypopyon, worse initial VA, longer time to epithelial defect closure, and history of glaucoma.

The Prevalence of Bacteria, Fungi, Viruses, and Acanthamoeba From 3,004 Cases of Keratitis, Endophthalmitis, and Conjunctivitis.

PURPOSE: The definitive identification of ocular pathogens optimizes effective treatment. Although the types of ocular pathogens are known; there is less definitive information on the prevalence of causative infections including viruses, fungi, and protozoa, which is the focus of this retrospective laboratory review. METHODS: Data used for laboratory certification were reviewed for the detection of bacteria, viruses, fungi, and protozoa, from patients with infectious keratitis, endophthalmitis, and conjunctivitis. The main outcome parameter was laboratory-positive ocular infection. RESULTS: The distribution of infectious agents for keratitis (n=1,387) (2004-2018) was bacteria 72.1% (Staphylococcus aureus 20.3%, Pseudomonas aeruginosa 18%, Streptococcus spp. 8.5%, other gram-positives 12.4%, and other gram-negatives 12.9%), Herpes simplex virus 16%, fungi 6.7%, and Acanthamoeba 5.2%. For endophthalmitis, (n=770) (1993-2018), the bacterial distribution was coagulase-negative Staphylococcus 54%, Streptococcus spp. 21%, S. aureus 10%, other gram-positives 8%, and gram-negatives 7%. The distribution for conjunctivitis (n=847) (2004-2018) was Adenovirus 34%, S. aureus 25.5%, Streptococcus pneumoniae 9%, Haemophilus 9%, other gram-negatives 8.8%, other gram-positives 6%, coagulase-negative Staphylococcus 4.5% and Chlamydia 3.2%. CONCLUSION: An updated monitoring of ocular pathogens creates an awareness of the different infectious etiologies and the importance of laboratory studies. This information can determine treatment needs for infectious ocular diseases.