A 10-Year Retrospective Clinical Analysis of Fungal Keratitis in a Portuguese Tertiary Centre

Microbiological Profile of Infectious Keratitis During Covid-19 Pandemic

Purpose

The Covid-19 pandemic introduced significant changes in our daily life, including the widespread use of face masks. The purpose of this study was to assess if significant changes occurred in the microbiological profile of infectious keratitis.

Patients and Methods

A retrospective study was performed, based on a survey review of the electronic medical records of all patients with presumed infectious keratitis, between March 2020 and October 2021. The microbiological isolates in this sample (pandemic group) were compared with those obtained in our center between 2009 and 2018 (pre-pandemic group).

Results

A total of 194 samples were included in the pandemic group. We obtained a culture-positivity rate of 43.3%, which was significantly higher when compared with the pre-pandemic data (35.15%, p = 0.033). Several further significant differences were found between the pandemic and the pre-pandemic groups: the proportion of bacteria, including gram-positive and gram-negative groups, was higher in our sample (pre-pandemic vs pandemic: 76.78% vs 83.33%, p = 0.010; 53.35% vs 60.71%, p = 0.016; 23.43% vs 34.52%, p = 0.005, respectively); two populations of Gram-positive bacteria found in this study were not isolated in the pre-pandemic sample - Dolosigranulum pigrum and Propionibacterium spp.; and two bacterial isolates were significantly increased in our sample - Corynebacterium spp. (18.41% vs 29.76%, p = 0.003) and Pseudomonas aeruginosa (9.00% vs 16.66%, p = 0.012).

Conclusion

In conclusion, significant changes were found in the microbiological profile of infectious keratitis in our center during the Covid-19 pandemic. While these changes could be related to face mask use, more observational and experimental studies are needed to explore this possible association.

Clinicopathological Correlation of Microbial Keratitis and Ahead: Is There a Corneal Sepsis?

Microbial, infectious keratitis is a relevant indication for penetrating keratoplasty. The requirement for transplantation results in histopathological examination of the entire thickness of the cornea. Although the clinical diagnosis is not always possible to confirm, pathology can support diagnostic evidence of clinical presentation and pathogenesis. This is achieved with multiple methods from cytology, histochemistry, immunohistology, molecular pathology and in rare cases electron microscopy. These allow tissue-based detection of previous and parallel diseases and the responsible pathogens. The failure of satisfactory clinicopathological correlation raises the question whether a suspected pathogen was not ultimately responsible for destroyed corneal tissue. The pathogenesis of keratitis requiring transplantation is not yet completely understood, also on the experimental level. The development of such a keratitis can lead to a clinical symptomatology which can be described as "threatening organ dysfunction", a term used in sepsis research. Considering recent literature, possible correlations between sepsis and microbial keratitis and their relation to histopathology are discussed.

Diagnosing Fungal Keratitis and Simultaneously Identifying Fusarium and Aspergillus Keratitis with a Dot Hybridization Array

Fungal keratitis (FK) is one of the most common microbial keratitis, which often leads to poor prognosis as a result of delayed diagnosis. Several studies implied that early differentiation of the two major FK, Fusarium and Aspergillus keratitis, could be helpful in selecting effective anti-fungal regimens. Therefore, a novel dot hybridization array (DHA) was developed to diagnose FK and differentiate Fusarium and Aspergillus keratitis in this study. One hundred forty-six corneal scrapes obtained from one hundred forty-six subjects impressed with clinically suspected FK were used to evaluate the performance of the DHA. Among these patients, 107 (73.3%) patients had actual FK confirmed by culture and DNA sequencing. We found that the DHA had 93.5% sensitivity and 97.4% specificity in diagnosing FK. In addition, this array had 93.2% sensitivity and 93.8% specificity in diagnosing Fusarium keratitis, as well as 83.3% sensitivity and 100% specificity in diagnosing Aspergillus keratitis. Furthermore, it had 83.9% sensitivity and 100% specificity in identifying Fusarium solani keratitis. Thus, this newly developed DHA will be beneficial to earlier diagnosis, more precise treatment, and improve prognosis of FK, by minimizing medical refractory events and surgical needs.

Clinical Characteristics and Outcomes of Fungal Keratitis in the United Kingdom 2011-2020: A 10-Year Study

Fungal keratitis (FK) is a serious ocular infection that often poses significant diagnostic and therapeutic dilemmas. This study aimed to examine the causes, clinical characteristics, outcomes, and prognostic factors of FK in the UK. All culture-positive and culture-negative presumed FK (with complete data) that presented to Queen’s Medical Centre, Nottingham, and the Queen Victoria Hospital, East Grinstead, between 2011 and 2020 were included. We included 117 patients (n = 117 eyes) with FK in this study. The mean age was 59.0 ± 19.6 years (range, 4–92 years) and 51.3% of patients were female. Fifty-three fungal isolates were identified from 52 (44.4%) culture-positive cases, with Candida spp. (33, 62.3%), Fusarium spp. (9, 17.0%), and Aspergillus spp. (5, 9.4%) being the most common organisms. Ocular surface disease (60, 51.3%), prior corneal surgery (44, 37.6%), and systemic immunosuppression (42, 35.9%) were the three most common risk factors. Hospitalisation for intensive treatment was required for 95 (81.2%) patients, with a duration of 18.9 ± 16.3 days. Sixty-six (56.4%) patients required additional surgical interventions for eradicating the infection. Emergency therapeutic/tectonic keratoplasty was performed in 29 (24.8%) cases, though 13 (44.8%) of them failed at final follow-up. The final corrected-distance-visual-acuity (CDVA) was 1.67 ± 1.08 logMAR. Multivariable logistic regression analyses demonstrated increased age, large infiltrate size (>3 mm), and poor presenting CDVA (<1.0 logMAR) as significant negative predictive factors for poor visual outcome (CDVA of <1.0 logMAR) and poor corneal healing (>60 days of healing time or occurrence of corneal perforation requiring emergency keratoplasty; all p < 0.05). In conclusion, FK represents a difficult-to-treat ocular infection that often results in poor visual outcomes, with a high need for surgical interventions. Innovative treatment strategies are urgently required to tackle this unmet need.