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.

Corneal Ulcers (Infectious Keratitis)

Microbial keratitis is an infectious process that occurs due to the proliferation of microorganisms (bacteria, fungi, viruses, and parasites) and associated inflammation and tissue destruction. Smears and cultures are indicated for the isolation of microorganisms and for making the correct diagnosis and immediate initiation of antimicrobial therapy, especially in cases where corneal infiltrate is chronic, large, deep, or atypical. Microbial keratitis is considered a vision-threatening ocular emergency. Therefore, this chapter, which consists of almost all cases studied before and after treatment, highlights the importance of early recognition, isolation of specific microorganisms, and sensitivity-based therapy. Also, the evaluation of these cases helps to show the appearance of the eye after the therapeutic treatment and demonstrates the emergency of immediate surgery to save the eyeball in cases where medical treatment is ineffective. The authors have summarized the treatment options they have used for bacterial, fungal, acanthamoeba, and herpetic keratitis cases.

Cosmetic contact lenses: beauty can be blinding

Background: Although cosmetic contact lenses are ideally indicated for patients with corneal and iris abnormalities, they are currently fashionable among the younger generation of emmetropes to enhance their physical appearance. Cosmetic contact lens wearers carry a greater risk of microbial keratitis, even more so with counterfeit ones.Case presentation: Here, we report two cases of counterfeit cosmetic contact lens wearers with Acanthamoeba keratitis (AK) who were misdiagnosed as herpes simplex virus (HSV) keratitis.Conclusion: AK is a sight-threatening complication among contact lens wearers. Since clinically AK may masquerade as HSV, early diagnosis of AK is often delayed. As both microorganisms can mimic each other, determining the co-existence of both infections can be challenging. Delay in initiating proper treatment can lead to blinding complications.

Contact Lens Associated Bacterial Keratitis: Common Organisms, Antibiotic Therapy, and Global Resistance Trends: A Systematic Review

IntroductionContact lens wearing has been increased globally during recent decades, which is one of the main risk factors for developing microbial keratitis. Microbial keratitis is a severe and dangerous condition that causes cornea inflammation. It can lead to corneal scarring and perforation or even endophthalmitis and visual loss if it remains untreated. Among bacterial, fungal, protozoal, and viral agents which can cause microbial keratitis, bacteria are the most common cause. Therefore, in this study, we aim to find common causative bacteria, sensitivity, and resistance to antibiotics and the outcome of antibiotic therapy in contact lens-related bacterial keratitis.MethodsA systematic search was carried out in PubMed/Medline, EMBASE, and Web of Science for published studies and medRxiv for preprints up to February 30, 2021, and May 14, 2021, respectively. A combination of the following keywords was used: “Infection”, “Corneal infection”, “Keratitis”, “Microbial keratitis”, and “Contact lens”, Also, we used the “Contact lenses” MeSH term. Lists of references for each selected article and relevant review articles were hand-searched to identify further studies.ResultsTwenty-six articles were included. From 1991 to 2018, 2,916 episodes of contact lens-related microbial keratitis) CLMK(with 1,642 episodes of proven bacterial keratitis have been reviewed in these studies. Studies were conducted in 17 countries with different geographical regions, and four studies were conducted in Iran, which is the highest number of studies among these countries. According to 20 studies, the mean age of patients was 30.77 years. Females with 61.87% were more than males in 19 studies. A percentage of 92.3% of patients used soft contact lenses, and 7.7% of patients used hard contact lenses (including RGP), according to 16 studies. Pseudomonas aeruginosa, Staphylococcus spp., and Serratia marcescens were the three most common bacteria isolated from samples of patients with contact lens-related bacterial keratitis. Overall, isolated bacteria were most sensitive to fluoroquinolones and aminoglycosides, especially ciprofloxacin and gentamicin respectively, and most resistant against penicillin and cephalosporins especially cefazolin and chloramphenicol. Almost all patients responded well to antibiotic therapy, with some exceptions that needed further surgical interventions.ConclusionAntibiotics are efficient for treating almost all patients with contact lens-related bacterial keratitis if they are appropriately chosen based on common germs in every geographical region and the sensitivity and resistance of these germs against them. In this regard, Pseudomonas aeruginosa is the most common causative germ of contact lens-associated bacterial keratitis all over the world and is almost fully sensitive to ciprofloxacin. Because of some different results about the sensitivity and resistance of germs against some antibiotics like gentamicin, vancomycin, and chloramphenicol in the Middle East region, especially Iran, more in vitro and clinical studies are suggested.