Denise de Freitas

An outbreak of Mycobacterium chelonae infection after LASIK

OBJECTIVE To describe an outbreak of mycobacterial keratitis after laser in situ keratomileusis (LASIK), including the microbiologic investigation, clinical findings, treatment response, and outcome. DESIGN Retrospective, noncomparative, interventional case series. PARTICIPANTS Patients (n = 10) who underwent LASIK surgery between August 22 and September 4, 2000, and developed mycobacterial infection. METHODS Patients were prospectively followed in relation to microbiologic investigation, clinical findings, treatment response, and outcome. MAIN OUTCOME MEASURES Most patients underwent bilateral simultaneous LASIK. Postoperative infection was signaled by the appearance of corneal infiltrates in the third postoperative week. The microbiologic workup was performed on cultures obtained either by direct scraping of the cornea or by lifting the flap. Medical therapy was instituted based on drug susceptibility testing. Surgical interventions such as corneal debridement and flap removal were performed during recurrences or when there was no satisfactory clinical response. RESULTS Cultures revealed Mycobacterium subspecies chelonae. Patients were treated with topical clarithromycin (1%), tobramycin (1.4%), and ofloxacin (0.3%). Oral clarithromycin (500 mg twice a day) was prescribed for those patients who did not respond clinically to topical treatment. Four eyes healed on this regimen. Flap removal was necessary in seven eyes. CONCLUSIONS This report highlights mycobacteria as an etiologic infectious agent after LASIK. Diagnosis can be difficult and is often delayed. The treatment mainstay is prolonged antibiotic therapy. Surgical debridement and flap removal may shorten the disease course.

Corneal infections after implantation of intracorneal ring segments.

Purpose: To report risk factors, clinical course, and outcome in patients with infectious keratitis following implantation of intracorneal ring segments (ICRS). Methods: The records of 8 patients with culture-proven infectious keratitis after ICRS (Ferrara® or Intacs®) implantation were retrospectively reviewed. Age, gender, corneal findings, ocular abnormalities, the condition that led to ICRS implantation, immediate prior use of a contact lens, elapsed time between implantation and the onset of symptoms, previous medications, and systemic disorders were noted. Results: Culture-positive infectious keratitis developed in 7 eyes of 7 patients (2 men and 5 women) with a mean age of 35 years who underwent Ferrara implantantion for the treatment of keratoconus and in a 29-year-old man who underwent Intacs implantation for correction of low myopia. Contact lens use, diabetes, and trauma were factors possibly associated with the risk of infection in three cases. Microorganisms, identified in all cases, included Staphylococcus aureus, Streptococcus viridans, Streptococcus pneumoniae, Pseudomonas sp, Nocardia sp, Klebsiella sp, and Paecylomices sp. Onset of symptoms of infection varied from less than 1 week to 22 months postoperatively, depending on the infecting organism. Conclusions: Infectious keratitis following ICRS implantation is a sight-threatening complication for which early recognition and rapid institution of appropriate treatment may result in a better visual outcome.

Infectious post-LASIK crystalline keratopathy caused by nontuberculous mycobacteria.

Purpose. To report three cases of infectious crystalline keratopathy caused by non-tuberculous mycobacteria after LASIK surgery. Methods. Interventional case reports and literature review. Results. Infectious keratitis with clinical features of crystalline keratopathy after LASIK is described. Culture revealed Mycobacterium chelonae from the corneal scrapings of the three patients, all of whom underwent medical and surgical (debridement) treatment. Conclusions. Mycobacteria may cause infectious crystalline keratopathy after LASIK. The presence of crystalline keratopathy in patients that underwent LASIK must be considered an indicator of nontuberculous mycobacteria infection. Microbiologic work-up of a corneal specimen is required for the institution of appropriate therapy.

Twenty years of acanthamoeba keratitis

Purpose: We described the rate of Acanthamoeba keratitis (AK) in a referral eye center in São Paulo, Brazil, through a retrospective review of clinical and laboratorial records of patients over 2 decades. Methods: From 1987 to 2006, a total of 581 requests for amoebic laboratory workup in cases of infectious keratitis were investigated. Statistical analyses were applied to analyze a tendency of AK cases. Results: Acanthamoeba species were cultured from corneal scrapings of 185 patients, 5 of them with bilateral infection. Eighty-three percent of those patients were related with contact lens wear. Conclusions: The results suggested that patients with AK have persisted and increased over time at our ophthalmology center. Contact lenses showed to be a potential risk factor. Amoebic corneal infection can be considered as a new but well-established disease in Brazilian ophthalmology and visual sciences.

An Outbreak of Keratitis Caused by Mycobacterium immunogenum

ABSTRACT From 8 October to 12 November 2003, 36 patients underwent surgical correction of myopia in a São Paulo, Brazil, clinic. Five patients had clinical signs of infectious keratitis, and a Mycobacterium species with previously unreported patterns determined by PCR restriction enzyme analysis of the hsp65 gene and PCR restriction enzyme analysis of the 16S-23S rRNA internal transcribed spacer (ITS) was isolated from corneal scrapings from four of these patients. Subsequent evaluation by phenotypic tests and partial sequencing of the hsp65, sodA, rpoB, and 16S rRNA genes and the ITS supported the species identification as a variant of Mycobacterium immunogenum. The source of infection was not determined. The outbreak was caused by a single clone, as evidenced by identical pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus-PCR profiles. This is the first report of an outbreak where this species was isolated from infected tissues.

Random amplified polymorphic DNA profiles as a tool for the characterization of Brazilian keratitis isolates of the genus Acanthamoeba

The genus Acanthamoeba comprises free-living amebae identified as opportunistic pathogens of humans and other animal species. Morphological, biochemical and molecular approaches have shown wide genetic diversity within the genus. In an attempt to determine the genetic relatedness among isolates of Acanthamoeba we analyzed randomly amplified polymorphic DNA (RAPD) profiles of 11 Brazilian isolates from cases of human keratitis and 8 American type culture collection (ATCC) reference strains. We found that ATCC strains belonging to the same species present polymorphic RAPD profiles whereas strains of different species show very similar profiles. Although most Brazilian isolates could not be assigned with certainty to any of the reference species, they could be clustered according to pattern similarities. The results show that RAPD analysis is a useful tool for the rapid characterization of new isolates and the assessment of genetic relatedness of Acanthamoeba spp. A comparison between RAPD analyses and morphological characteristics of cyst stages is also discussed.

Assessing Efficacy of Combined Riboflavin and UV-A Light (365 nm) Treatment of Acanthamoeba Trophozoites

PURPOSE To assess the Acanthamoeba trophozoite viability in vitro and treatment of Acanthamoeba keratitis in a hamster model using ultraviolet light A (UV-A) and riboflavin (B2). METHODS A sample of Acanthamoeba sp. cultured was transferred to a 96-well plate and exposed to B2 and the UV-A light (365 nm wavelength) at a power density of 3 mW/cm(2), 8 mm spot diameter, for 30 minutes. The exposure was done in triplicate. Control groups were prepared in triplicate as well: blank control, UV-A only, riboflavin only, and dead control. Cell viability assessment was done using the trypan blue dye exclusion method. Acanthamoeba keratitis was induced in Chinese hamsters; who were randomly assigned to one of the animal groups: UV-A + B2, propamidine isethionate (Brolene; Sanofi-Aventis, Ellerslie, Auckland, Australia), UV-A + B2 + propamidine isethionate (Brolene), only UV-A, only B2, and blank. Throughout the 14 days after treatment the animals were examined clinically. Histology and clinical scores of all groups were compared. RESULTS The in vitro study showed no difference between the treatment group UV-A + B2 and the control groups. In the hamster keratitis model a significant improvement of clinical score was observed for the groups propamidine isethionate (Brolene) and UV-A + B2 + propamidine isethionate (Brolene) (P = 0.0067). Also a significant worsening of clinical score was observed in the other groups: UV-A + B2 group (P = 0.0084), only UV-A (P = 0.0078), B2 only (P = 0.0084), and blank (P = 0.0082). No difference was observed between propamidine isethionate (Brolene) and UV-A + B2 + propamidine isethionate (Brolene). CONCLUSIONS The adjunctive use of UV-A and B2 therapy did not demonstrate antitrophozoite activity; in vivo UV-A and B2 did not demonstrate efficacy in this model.

Aerobic bacterial conjunctival flora in diabetic patients.

Objective To study the aerobic conjunctival flora of diabetic patients and its relation to the presence and level of diabetic retinopathy and the duration of the disease. Methods One hundred three patients from the diabetic retinopathy screening program of the Federal University of São Paulo with no evidence of ocular surface disease were included. The diabetic patient cohort was compared with 60 nondiabetic subjects. All patients underwent slit-lamp evaluation, conjunctival scrapings, and indirect ophthalmoscopy. Results The frequency of positive conjunctival cultures was significantly higher in the diabetic group (94.18%) than in the nondiabetic group (73.33%). Among diabetic patients, a significantly higher frequency of positive cultures was detected in those with diabetic retinopathy than in those without retinopathy. Neither the duration of the diabetes nor the hypoglycemic therapy correlated with the culture results. Coagulase-negative Staphylococcus was the most common microorganism isolated, and its identification was more frequent in patients with retinopathy than in those without diabetic retinopathy. Conclusion Diabetic patients have a significantly higher number of positive conjunctival cultures. The presence of diabetic retinopathy was correlated with an increase in positive cultures and a higher proportion of coagulase-negative Staphylococcus.

Nocardial keratitis following myopic keratomileusis.

PURPOSE/METHODS Interface opacities were detected in a patient who underwent uncomplicated myopic keratomileusis. RESULTS AND DISCUSSION Nocardia asteroides keratitis was confirmed by microbiologic work-up and guided the correct treatment. The eye recovered 20/60 spectacle-corrected visual acuity and had a residual stromal scar.

Confocal microscopy in early diagnosis of Acanthamoeba keratitis.

PURPOSE This study correlated confocal microscopic images obtained using the Nidek ConfoScan 2.0 System in corneas with clinical suspicion of Acanthamoeba keratitis, with diagnosis confirmed by either cytological and/or histological analysis. METHODS Fifteen eyes of 14 patients with a clinical diagnosis of Acanthamoeba keratitis underwent confocal microscopy evaluation. RESULTS Fifteen eyes of 14 patients (one bilateral case) showed Acanthamoeba keratitis alterations that ranged from massive infestation to cicatricial opacity in the stroma. Ten patients (71%) were females. Mean age was 26 years (range 19 to 37 yr). All patients were contact lens wearers. CONCLUSION Confocal microscopy was a useful, noninvasive technique in the diagnosis and treatment of Acanthamoeba keratitis, especially in those cases in which corneal scraping, cytological analysis, and culture are negative. It also eliminated the necessity of tissue biopsy, considered an invasive procedure.