Classification of staphylococci isolated from ocular tissues.

A total of 145 strains of Gram-positive, catalase-positive, coagulase-positive, and coagulase-negative cocci isolated from the human eye were classified by the system of Baird-Parker (1966). These belonged to subgroups I, II, IV, and V and showed a wide range of antibiotic sensitivities unrelated to subgroup and category of lesion. The role of coagulase-negative staphylococci in producing postoperative ocular infections has been especially emphasised.

Comparison of enzyme-linked immunosorbent assay and haemagglutination inhibition test for the detection of Newcastle disease virus antibodies in human sera.

A comparison of haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) techniques for the detection of antibodies against Newcastle disease virus in sera from persons working in poultry farms and veterinary vaccine institutes and from the general population revealed that 22% more sera were positive by ELISA compared to HI. No samples were negative by ELISA but positive by HI. While HI titres of positive sera were found in the range 8-64, ELISA titres were between 16 and 512. It was interesting that though 78% sera had concordant results by the two tests, titres obtained by ELISA were nearly six times higher than those by HI.

Role of coagulase-negative staphylococci and micrococci in ocular disease.

Forty-nine strains of coagulase-negative staphylococci and 26 strains of micrococci isolated from human eyes were classified by the Baird-Parker system of 1966. The staphylococci belonged to subgroups II, III, IV, and V with one strain each in subgroups III and IV. However, when biotyped by Baird-Parker's system of 1974, less than 50% (23/49) of strains were typable and they belonged to biotypes 1 and 2. With our proposed modified classification all strains could be classified into biotypes 1, 2, and 3. All the 26 strains of micrococci belonged to subgroup VII. Staphylococci isolated from diverse sources produced, qualitatively and quantitatively, different corneal pathology in rabbits when compared to those isolated from healthy conjunctiva. This bore no relation to the present system of subtyping based on biochemical reactions. Micrococci were incapable of producing experimental corneal lesions in the rabbit.

Acute bacterial infections of the eye: their aetiology and treatment.

The aerobic microbial flora of 823 eyes with acute bacterial conjunctivitis, corneal ulceration, dacryocystitis, discharging sockets, blepharitis, and postoperative infections has been investigated. Staphylococci, Streptococcus pneumoniae, and nonfermenting Gram-negative bacilli including Pseudomonas aeruginosa were the main pathogens. Fermenting coliforms were also infrequently isolated. The least overall resistance of 30.9% was to chloramphenicol, but no one antibiotic was effective against all pathogens. Cloxacillin is the best drug for staphylococcal and polymyxin B for pseudomonas infections.

Ocular chlamydial zoonosis: an experimental study in monkeys.

Two locally isolated strains of Chlamydia psittaci from faeces of apparently healthy sheep and conjunctiva of Holstein heifers suffering from conjunctivitis and pneumonia were used for ocular experimental studies in 7 Rhesus monkeys. Titrated (ELD50 10(3.6)/0.2 ml and 10(4.5)/0.2 ml) partially purified yolk sac suspension of each strain was instilled onto conjunctiva of each animal. The clinical and laboratory studies were followed till 8 weeks post-infection. Both the strains produced trachoma like follicles (0.3-0.5 mm dia) preferably on lower conjunctiva between 2-4 weeks of post-infection. Pannus was not observed in any of the experimental eye. Laboratory studies revealed a good correlation between reisolation, fluorescent antibody test and cytology between 2-4 weeks of post-infection. Highest complement fixing antibody titre 1:32 was recorded in 4 out of 7 animals. The studies indicated that both the animal strains had no barrier across ocular tissues in monkeys, vis-à-vis human conjunctiva.

Ocular pathogenesis of Newcastle disease virus in rabbits and monkeys.

Studies on the ocular pathogenesis of Newcastle disease virus (NDV) in rabbits and monkeys revealed that conjunctivitis can only be produced by the virus when conjunctival epithelium is traumatized; multiple instillations of large doses of virus over the intact conjunctiva failed to do so. The presence of serum HI antibodies showed no correlation with the clinical form of the disease in rabbits. However, in monkeys, the disease showed a uniform pattern of immune response irrespective of the strain of the virus. Monkeys may be useful for further studies.

Experimental intraocular nocardiosis.

We attempted to produce intraocular nocardiosis in rabbits. The clinical features and evolution of the disease and the role of corticosteroids was observed. N. asteroides suspension when injected into the anterior chamber produced a self limited nodular iridocyclitis. Local or systemic corticosteroids produced a severe anterior uveitis and progressive endophthalmitis. The organisms could be demonstrated from aqueous smears at the time of enucleation. When the suspension was injected into the vitreous cavity, it produced endophthalmitis. Local or systemic corticosteroids administration suppressed the anterior uveal inflammation and produced a purulent subconjunctival granuloma.

Microbial contamination of donor eyes.

A total number of 1,516 donor eyes received from various sources during the years 1973-1985 were subjected to the isolation of bacterial contamination. The bacterial cultures taken from the pretreatment eyeball showed culture growth in 366 (24.1%) eyes. Of the 366 positive cultures, 331 (21.8%) were bacterial and 35 (2.3%) were fungal. Amongst the bacterial the major contamination was by staphylococcus aureus and albus and pseudomonas aeruginosa. Gentamicin was found to be the most sensitive antibiotic against a wider group of organisms, the next being chloramphenicol. Thus, treatment of a cadaver eye with a solution of normal saline containing 0.1-0.5 mg/ml of gentamicin is recommended before and after the donor eye is enucleated.

Fungal flora in congenital dacryocystitis.

In this study, 86 eyes in 66 cases (20 bilateral) of congenital dacryocystitis were analysed for fungal growth. Fungi alone were isolated in 12 eyes (13.95%) and in 14 eyes (16.28%) together with bacteria--a total of 26 positive for fungus in 86 eyes (30.23%). These 26 eyes yielded on fungal culture a total of 28 isolates (in 2 eyes, another fungus was isolated on repeat culture). 11 types of fungi were cultured--C. albicans and A. niger accounted for 5 each out of 28. To the best of our knowledge this is the first report in the literature of fungal flora analysed in congenital dacryocystitis--not surprisingly, more than 30% of eyes were positive for fungus. Systemic studies of fungal flora in dacryocystitis are very few, and hardly any literature on this subject exists in congenital dacryocystitis. This study is an attempt to determine the frequency and clinical significance of fungi isolated from cases of congenital dacryocystitis.

Conjunctival microbial flora in leprosy.

Conjunctival sacs of seventy-one leprosy patients, paramedical and medical personnel working in a Leprosy Home were cultured. None of these eyes had any pathology of the outer eye. Surprisingly, 46.2% of the culturally positive eyes carried accepted pathogens, Staphylococcus aureus being the commonest. Determining the preoperative bacterial flora and their elimination before undertaking intraocular surgery is recommended.