A case of infectious crystalline keratopathy occurring long after penetrating keratoplasty

Successful Management of Infectious Crystalline Keratopathy with Intrastromal Antibiotic Injections

Purpose. To report the successful treatment of a case of presumed infectious crystalline keratopathy with repeated intrastromal antibiotic injections in a cornea graft in the setting of severe ocular graft-vs.-host-disease (GVHD). Observations. A 62-year-old man with a history of ocular GVHD and tectonic penetrating keratoplasty (PK) for corneal melt from herpes zoster keratopathy developed presumed infectious crystalline keratopathy (ICK) in the corneal graft. Given the patient's complicated ocular history, chronic immunosuppression and new cardiac comorbidities, a therapeutic PK would most likely fail. Efforts were then directed to rescue the graft with minimally invasive approaches. Two separate intrastromal injections of cefuroxime and moxifloxacin successfully treated his ICK. Conclusions and Importance. This case supports a role for repeated intrastromal antibiotic injections in patients with ICK refractory to topical antibiotic therapy, which might eliminate the need for therapeutic PK and preserve vision.

Infectious crystalline keratopathy

Infectious crystalline keratopathy was first reported by Gorovoy and colleagues in 1983 when they identified bacteria colonizing a cornea after a penetrating keratoplasty. Subsequent cases have elaborated on the organisms responsible and the management outcomes. Patients present with a white or gray branching opacity originating from an epithelial defect, commonly after a penetrating keratoplasty. Local immunosuppression contributes to the quiescent nature and the limited inflammatory response associated with infectious crystalline keratopathy. Diagnosis of the infective pathogens may be difficult, with a corneal scraping often being too superficial to obtain an adequate specimen. A biofilm is present that advantages microorganism survival, reduces antibiotic bioavailability, and inhibits diagnostic microbial detection. Treatment begins with topical antimicrobials, initially broad spectrum and then targeted to microorganism sensitivity. Adjunctive therapies to enhance the efficacy of treatment include disruption of the microorganism biofilm by laser, intrastromal antibiotics, and keratectomy. In recalcitrant cases, or where corneal scarring ensues, corneal transplantation is required.

Infectious crystalline keratopathy in dogs and cats: clinical, in vivo confocal microscopic, histopathologic, and microbiologic features of eight cases

OBJECTIVE

To describe clinical, in vivo confocal microscopic, histopathologic, and microbiologic features of canine and feline cases of infectious crystalline keratopathy (ICK).

ANIMALS STUDIED

Six dogs and two cats with naturally acquired ICK.

PROCEDURES

Medical records of dogs and cats with a clinical diagnosis of ICK were reviewed. Signalment, medical history, clinical findings, and diagnostic evaluations were retrieved, including corneal cytology, histopathology, in vivo confocal microscopy, and microbiology results.

RESULTS

All animals presented with fine, needle-like, and branching white crystalline anterior stromal opacities emanating from corneal facets or corneal epithelial defects. Mild conjunctival hyperemia and anterior uveitis were frequently present. Concurrent ocular and systemic diseases were common, including keratoconjunctivitis sicca, corneal sequestrum, diabetes mellitus, hyperadrenocorticism, and malignant neoplasia. Bacteria, with minimal or absent leukocytes, were identified by cytology and histopathology. Histopathologically, the crystalline corneal opacities corresponded with dense accumulations of bacteria present in the interlamellar stromal spaces and forming cord-like projections within the stroma. In vivo confocal microscopy demonstrated deposits of reflective crystalline or amorphous structures within the stroma with a paucity of associated inflammatory changes. The most frequently cultured bacteria were alpha-hemolytic Streptococcus and Staphylococcus species. Resolution of clinical lesions was achieved in most cases with long-term medical or surgical therapy; however, the initiation of medical treatment was associated with an acute, dramatic onset of severe keratitis and anterior uveitis in some animals.

CONCLUSIONS

Infectious crystalline keratopathy in dogs and cats shares many features with this condition in human patients. Prolonged medical therapy, or surgical intervention, is required for resolution.

Polymerase chain reaction and DNA typing for diagnosis of infectious crystalline keratopathy

A 63-year-old man developed infectious crystalline keratopathy (ICK) in his right eye 1 year after phacoemulsification. The white peripheral lesion was adjacent to the corneal phacoemulsification incision. Infiltrates in the form of creamy-white, midstromal branching, needle-like opacities without evidence of inflammatory cells were noted. A corneal biopsy by double lamellar flap was done and studied by 3 techniques: microbiological culture, stain, and polymerase chain reaction (PCR). Fungal and bacterial PCR were positive. A second sample was necessary to obtain a positive stain and culture. The DNA sequence analysis showed Candida parapsilosis and Staphylococcus aureus as the causal agents of the crystalline keratopathy. Treatment was started with amphotericin B 1% and cefazolin 6 times a day, and systemic voriconazole was recommended. This is the first reported case of ICK after cataract surgery. Polymerase chain reaction amplification and subsequent DNA typing were useful tools in detecting and identifying the ocular pathogens involved in this case.

Candida parapsilosis keratitis

PURPOSE

To present clinical, microbiologic, and histopathologic features of keratitis due to Candida parapsilosis.

METHODS

Clinicomicrobiologic evaluation of four patients (four eyes) with culture-proven C. parapsilosis keratitis. The patients were evaluated for symptoms, visual acuity, clinical observations, microbiologic examination of corneal scrapings, and pathologic examination of corneal buttons.

RESULTS

Three cases were observed after penetrating keratoplasty, and one case occurred after inhalation of corticosteroids. Clinical presentation of C. parapsilosis keratitis showed a great diversity. There was one case of crystalline keratopathy and three cases of suppurative corneal infiltrate. Histopathology of corneal buttons showed interlamellar accumulations of yeast. Medical treatment included topical amphotericin B and systemic triazoles. Penetrating keratoplasty was required in three patients.

CONCLUSION

Risk factors for C. parapsilosis keratitis may include corticosteroid use and prior corneal transplantation. The prognosis of C. parapsilosis keratitis with antifungal and surgical therapy may vary from good visual outcome to intraocular extension with phthisis bulbi.

Demonstration of biofilm in infectious crystalline keratopathy using ruthenium red and electron microscopy

OBJECTIVE

Bacterial biofilm formation has been implicated in the pathogenesis of infectious crystalline keratopathy. Biofilm cannot be visualized by electron microscopy without the addition of a fixative that stabilizes the polysaccharide-rich bacterial extracellular matrix that surrounds the bacterial colonies in a biofilm. We used ruthenium red as a fixative to evaluate corneal biopsy specimens for the presence of bacterial biofilm in three cases of infectious crystalline keratopathy (ICK) and five cases of chronic microbial keratitis without crystalline changes.

DESIGN

Case series with clinicopathologic correlation.

PARTICIPANTS

Eight patients underwent corneal biopsy or therapeutic keratoplasty as part of their management for chronic unresponsive microbial keratitis.

METHODS

The corneal specimens removed were trisected for microbiology, pathology, and transmission electron microscopy (TEM). The TEM specimens were fixed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer with 0.05% ruthenium red.

MAIN OUTCOME MEASURES

Demonstration of bacterial biofilm with TEM.

RESULTS

TEM demonstrated organisms with a surrounding extracellular matrix consistent with a bacterial biofilm in the three cases of ICK but not in the five other cases of chronic microbial keratitis.

CONCLUSIONS

The presence of biofilm in ICK can be demonstrated with TEM with appropriate fixation techniques that stabilize the bacterial extracellular matrix. Biofilm stains intensely with periodic acid-Schiff because of the polysaccharide-rich extracellular matrix and weakly with Gram stain because of the high proportion of nonviable organisms. Biofilm formation occurs in ICK but probably not in chronic bacterial keratitis without crystalline changes. Secretion of an extracellular matrix by bacteria to form a biofilm is a response to a nutrient-deprived environment in which growth and replication is depressed. The extracellular matrix of the biofilm may mask bacterial antigens, explaining the relative lack of inflammatory response in these infections. It may also be one of the mechanisms explaining the resistance to in vivo antimicrobial therapy when in vitro sensitivities have been proven.