Bilateral Bacterial Keratitis in Three Patients Following Photorefractive Keratectomy

Coexistence of Fungal Keratitis in Bilateral Sequential Microsporidial Keratitis - A Rare Case Presentation

AIM

To report a case of bilateral microsporidiosis with coexisting fungal infection in one eye.

METHOD

Retrospective interventional case report.

RESULTS

A 61-year-old man with uncontrolled diabetes presented with clinical and microbiological features of non-resolving fungal keratitis in the right eye since 3 months and underwent therapeutic penetrating keratoplasty (TPK) for the same. Fungal filaments along with oval bodies suspicious of microconidia were noted on calcofluor stain. A week following TPK, the patient presented with features of viral keratouveitis in the left eye which on microbiology was confirmed as microsporidiosis. Retrospectively, the right eye microbiology slides were reassessed, which confirmed the coexistence of fungus with microsporidiosis by acid-fast stain and polymerase chain reaction.

CONCLUSION

Structural resemblance of microconidia with microsporidial spores can be misleading, thus creating a need for awareness regarding the possible coexistence along with a need to suspect microsporidiosis in nonresponding clinically resembling viral keratitis.

Bipolaris keratitis following photorefractive keratectomy: Case report

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Photorefractive keratectomy is a common refractive surgery which has excellent outcome in correcting refractive errors.

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This procedure carries the risk of infectious keratitis due to removal of epithelial layer during the procedure.

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Few cases has been reported with fungal keratitis following the procedure.

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In the current case the culture was positive for bipolaris species and the patient showed excellent response to medical treatment.

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Early diagnosis, appropriate laboratory testing, close observation and aggressive antifungal therapy can result in good outcomes.

Introduction

Fungal keratitis is an uncommon condition that can occur after ocular surgery or trauma to the eye. Some cases have been reported after corneal refractive surgery. Most cases of keratitis following refractive surgery are due to gram-positive bacteria. However, there are a few reports in the literature of fungal and protozoal infections.

Case Presentation

A 29-year-old healthy male developed fungal keratitis Five days following photorefractive keratectomy.

Clinical findings and Investigations

The patient was admitted to the hospital, corneal scraping was performed and sent for staining and routine cultures. A corneal swab was also performed and sent for polymerase chain reaction (PCR). On day 10 post-admission, the fungal culture was positive for Bipolaris.

Intervention and Outcome

Intensive topical antifungal drops were started initially then tapered when clinical improvement was evident. The patient had good final outcome with preservation of good vision and free of symptoms six months following the infection.

Relevance and Impact

Fungal keratitis following corneal refractive surgery is rare. However, it is an infection that can potentially lead to poor outcomes if appropriate management is delayed. Therefore, a high index of suspicion is required especially when multiple risk factors is present.

Bilateral simultaneous infective keratitis

AIM

To analyze the demographics, risk factors, clinical and microbiological characteristics of cases of bilateral simultaneous infective keratitis.

METHODS

In this retrospective case series, patients with clinical evidence of bilateral simultaneous infective keratitis were identified from January 1, 2011 to August 31, 2016. Demographics, risk factors, clinical and microbiological characteristics, and treatment outcomes were analyzed.

RESULTS

Five patients (ten eyes) with bilateral simultaneous infective keratitis were identified. The mean age was 32.8 years (SD,±8.8; range, 24-44). All the patients were disposable soft contact lens wearers before presentation. The average size of the infiltrate was 4.76mm² (SD±9.0; range, 0.2-31.34). A total of 4 types of bacteria were isolated, with Pseudomonas aeruginosa being the most frequently isolated bacteria involving 5 eyes of four patients. Infection resolved with medical treatment in 9 eyes, 1 patient required therapeutic corneal transplantation for impending corneal perforation. The average time taken for infection to resolve was 6.7days (SD±4.5; range, 2-16).

CONCLUSIONS

In this case series, the most common risk factor of bilateral simultaneous microbial keratitis was use of soft disposable contact lens and the most commonly isolated bacteria was Pseudomonas aeruginosa. Bilateral simultaneous infective keratitis is uncommon and is a serious complication of contact lens use in immunocompetent adult patients.

Extracellular matrix protein lumican promotes clearance and resolution of Pseudomonas aeruginosa keratitis in a mouse model

Lumican is an extracellular protein that associates with CD14 on the surface of macrophages and neutrophils, and promotes CD14-TLR4 mediated response to bacterial lipopolysaccharides (LPS). Lumican-deficient (Lum(-/-)) mice and macrophages are impaired in TLR4 signals; raising the possibility that lumican may regulate host response to live bacterial infections. In a recent study we showed that invitro Lum(-/-) macrophages are impaired in phagocytosis of gram-negative bacteria and in a lung infection model the Lum(-/-) mice showed poor survival. The cornea is an immune privileged barrier tissue that relies primarily on innate immunity to protect against ocular infections. Lumican is a major component of the cornea, yet its role in counteracting live bacteria in the cornea remains poorly understood. Here we investigated Pseudomonas aeruginosa infections of the cornea in Lum(-/-) mice. By flow cytometry we found that 24 hours after infection macrophage and neutrophil counts were lower in the cornea of Lum(-/-) mice compared to wild types. Infected Lum(-/-) corneas showed lower levels of the leukocyte chemoattractant CXCL1 by 24-48 hours of infection, and increased bacterial counts up to 5 days after infection, compared to Lum(+/-) mice. The pro-inflammatory cytokine TNF-α was comparably low 24 hours after infection, but significantly higher in the Lum(-/-) compared to Lum(+/-) infected corneas by 2-5 days after infection. Taken together, the results indicate that lumican facilitates development of an innate immune response at the earlier stages of infection and lumican deficiency leads to poor bacterial clearance and resolution of corneal inflammation at a later stage.

Microbial keratitis after corneal laser refractive surgery

Corneal laser refractive surgery is increasingly being performed on patients with the aim of improving unaided vision. Most candidates for surgery have excellent spectacle- or contact lens-corrected vision. Although microbial keratitis following refractive surgery is a rare complication, and usually has a good visual outcome, it can be sight-threatening. The spectrum of pathogens differs to other causes of microbial keratitis, such as contact lens-associated keratitis, and a different management approach is required. Postoperatively, patients are prescribed topical steroids and broad-spectrum topical antibiotics, typically fluoroquinolones. These do not cover unusual organisms, such as fungi, Nocardia, Acanthamoeba and some atypical mycobacteria. In post-laser-assisted in situ keratomileusis microbial keratitis, the lamellar flap should be lifted to acquire samples for specific microbiological examination, including these atypical organisms. Confocal microscopy is a noninvasive test that provides morphological information, and is operator dependent, but may assist in the rapid diagnosis of fungal, Acanthamoeba or Norcardia keratitis. PCR is not in widespread use, but has high sensitivity and specificity, and may facilitate early diagnosis and specific treatment of the causative organism, which is critical in obtaining the best clinical outcome.

Outbreak of Nocardia keratitis after photorefractive keratectomy: clinical, microbiological, histopathological, and confocal scan study

Nocardia keratitis occurred in 4 eyes of 3 patients (2 women and 1 man) who had photorefractive keratectomy (PRK) by the same surgeon at the same center. Two eyes of the first 2 patients required lamellar keratectomy to debulk the involved stroma and obtain specimens for microbiological and histopathological evaluation. Light microscopic examination disclosed gram-positive and acid-fast filaments of Nocardia that were confirmed by the microbiological results. Diagnosis of Nocardia keratitis in the third case was not as challenging as in the first 2 cases because of a high index of suspicion. Confocal scans of all cases disclosed hyperreflective and slender, fibril-like structures in the corneal stroma. All eyes responded favorably to topical amikacin and the infection resolved without recurrence. The most probable cause of the outbreak was inadequate attention to sterility during surgery.