Claudete Inês Locatelli

CONJUNCTIVAL ENDOGENOUS MICROBIOTA IN PATIENTS SUBMITTED TO CATARACT SURGERY

Bacterial isolation, identification and antimicrobial susceptibility tests were carried out in ocular material collected with swab and polimethylmethacrylate (PMMA) or silicone intraocular lenses (IOL) from forty six patients submitted to cataract surgery. Seventy six isolates and seven different microorganisms were identified. Coagulase-negative staphylococci (CNS) were the predominant microorganisms isolated from swabs (71.4% of cases), PMMA lenses (81.3%) and silicon lenses (77.8%). Coagulase-negative staphylococci isolates revealed high resistance to penicillin G followed by tetracycline, chloramphenicol and aminoglicosides. However, these isolates displayed great susceptibility to vancomycin, cephalothin and ofloxacin. Except for penicillin G, Staphylococcus aureus was very sensitive to the antimicrobial agents including oxacillin. Among Gram-negatives, Proteus mirabilis was prevalent and presented high resistance to tetracycline and chloramphenicol. Enterococcus isolates were vancomycin sensitive.

Aderência bacteriana in vitro a lentes intra-oculares de polimetilmetacrilato e de silicone

PURPOSE: To evaluate bacterial adherence to silicone and polymetylmethacrylate (PMMA) intraocular lenses as a risk factor for postsurgery endophthalmitis by using an in vitro model with three potentially pathogenic microorganisms. METHODS: In vitro experiments were carried out with the Staphylococcus aureus ATCC 29213, Staphylococcus epidermidis (clinical isolate) and Pseudomonas aeruginosa ATCC 27853 strains including growth curves, tests to verify capsule production, hydrophobicity and adherence to different materials as well as optical microscopy, scanning electronic microscopy (SEM) and atomic force microscopy (AFM). RESULTS: No relation between capsule production, adherence of the strains tested and amount of microorganisms was observed; no statistically significant differences were detected between S. aureus and S. epidermidis adherence to polymetylmethacrylate and silicone intraocular lenses; P. aeruginosa was the most adherent microorganism to both materials. This adherence pattern was confirmed by SEM, while biofilm production by the three strains was visualized by AFM. CONCLUSIONS: In vitro experiments showed no differences of bacterial adherence between PMMA and silicone lenses, but P. aeruginosa displayed a greater level of adherence in relation to staphylococci. All three strains were shown to produce biofilm. Silicone was shown to be more hydrophobic when compared to polymethylmethacrylate.

Contaminação de halos doadores córneo-esclerais em ceratoplastia penetrante no Hospital de Clínicas de Porto Alegre

PURPOSE: To determine the incidence of positive corneoscleral rim cultures preserved in Optisol GS medium, to identify pathogens involved and possible recipient eye infection. METHODS: A hundred sixty-three corneoscleral rim cultures penetrating keratoplasties performed from January 2001 to January 2003 in the Hospital de Clinicas de Porto Alegre were reviewed. Enucleations and corneal storage were done as aseptic as possible and gentamicin 0.3% was instilled. Corneoscleral rim was divided into two segments, half was inoculated into Sabouraud broth and the other half into thioglycolate broth; inoculation into blood agar, chocolate agar and MacConkey agar was done later if necessary for pathogen identification. The receivers eye data were reviewed. RESULTS: There were eleven positive cultures (6.7%) out of 163 evaluated corneoscleral rim cultures. Of these, four were Staphylococcus epidermidis, one was Staphylococcus aureus, one was Serratia sp., one was Pseudomonas aeruginosa and the other four were different subtypes of Candida (two Candida sp., one Candida albicans and one Candida parapapilosis). All pathogens were resistant to gentamicin. None of the eleven cases of positive corneoscleral rim cultures resulted in ocular infection at the receivers eyes (six months follow-up). CONCLUSIONS: We found low rates of positive corneoscleral rim cultures after penetrating keratoplasty at the Porto Alegre Clinical Hospital. The most frequent involved pathogens were Staphylococcus sp and Candida sp. Although we did not identify any postoperative infection at the receivers eyes, we recommend corneoscleral rim culture for guidance of postoperative infection, a rare but possible devastating ocular event.

Acanthamoeba keratitis in Porto Alegre (southern Brazil): 28 cases and risk factors

The increasing use of contact lenses worldwide has led to an increase in cases of Acanthamoeba keratitis, which are often associated with inappropriate cleaning of contact lenses and lens cases. This study aimed to retrospectively review 28 cases of Acanthamoeba keratitis in Porto Alegre (southern Brazil) and identify the risk factors and clinical outcomes of affected patients. Most patients had higher education (66.6%), all were users of contact lenses, mostly women (67.9%). Most patients were soft contact lens wearers (66.7%) and 85.7% used multipurpose cleaning solutions. Sixteen patients (64.0%) used to wear contact lenses while swimming and/or bathing. Pain was the most common symptom (92.6%). For treatment, patients used polyhexamethylene biguanide drops (92.6%), propamidine isethionate drops (81.5%), chlorhexidine drops (55.6%), topical corticosteroids (63.0%), and systemic corticosteroids (37.0%). Herpes simplex keratitis was the most common misdiagnosis (72.7%). The majority of patients (76.0%) underwent a corneal transplant to control the disease.

Virulent T4 Acanthamoeba causing keratitis in a patient after swimming while wearing contact lenses in Southern Brazil

Several strains of free-living amoebae belonging to the genus Acanthamoeba can cause a painful sight-threatening disease of the cornea known as Acanthamoeba keratitis (AK). The numbers of AK cases keep rising worldwide mainly due to an increase in contact lens wearers and lack of hygiene in the maintenance of contact lenses and their cases. We report a case of AK in a healthy young woman admitted to the Hospital de Clinicas in Porto Alegre, southern Brazil. Corneal scrapings were examined for the presence of Acanthamoeba strains. The initial isolate was characterized by morphological and genotypic properties. The isolate belonged to group III according to Pussard and Pons’ cyst morphology. Analysis of its 18S rDNA sequence identified the isolate as genotype T4. The T4 genotype is the most commonly reported among keratitis isolates and the most common in environmental samples.