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.

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.

Chlamydial serology in uveitis.

Ninety seven sera, 53 from patients with Acute Anterior Uveitis and 44 from age and sex matched controls were tested for antichlamydial antibodies employing a recently developed technique of ELISA. Higher positivity of 27.0% was recorded in controls as against 17.0% in patients. The difference was statistically insignificant. All the subjects had trachoma at stage II-IV. Age and sex did not seem to influence the findings in both, the cases and controls. Through this study, the role of Chlamydia in the etiology of A. A. U. is not ascertained. Further studies are recommended.

Keratomycosis--a retrospective histopathologic and microbiologic analysis.

In this retrospective study, the results of concurrent histopathologic and microbiologic examinations of 61 corneal buttons were evaluated. These revealed histologic fungus identification in 77.04% of cases compared with culture examination which yielded fungal growth in 75.4% of cases. Mixed fungal and bacterial infection caused difficulty not only in isolation but also in demonstrating fungus in the tissue sections. Staphylococcus epidermidis was the most common isolate in cases of mixed infection. Aspergillus was the most prevalent nondematiaceous fungus. Dematiaceous fungi were isolated in culture in only 10.8% of our cases, and in none of them was the histopathology positive, indicating that they might have been contaminants.

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.

Pneumococci in ocular disease of children and their treatment.

A total of 171 isolates of Streptococcus pneumoniae were obtained from eyes of children who had congenital dacryocystitis, congenital cataract and glaucoma, acute bacterial conjunctivitis, corneal ulceration, nasolacrimal duct block, or discharging socket, or who had developed ectropion, endophthalmitis and orbital cellulitis. The highest number of strains was obtained from cases of dacryocystitis (74.4%), followed by conjunctivitis (8.2%) and those having developed nasolacrimal duct block (7.6%). The least overall resistance was to erythromycin (17.6%) and chloramphenicol (31.0%). Erythromycin being unavailable for ocular use in India, chloramphenicol was reported to be one of the best drugs against pneumococcal ocular infections in children, the other being cloxacillin, a 2.5% solution of which is made from injectable cloxacillin and used as an ophthalmic preparation. Their use on patients has met with considerable success. Nineteen out of 20 isolates were typeable--the types being 3, 46, 8, 28, 29, 45, 21 and 18. To the best of our knowledge, this is the first report from a developing country of serotyping ocular strains of pneumococci.

Postoperative ocular infections: an analysis of laboratory data on 750 cases.

From 1981-1982, 750 clinical specimens from patients who developed postoperative infections were processed in the ocular microbiology laboratory. Bacterial cultures were positive in 71.0%, fungal in 1.3% and another 1.4% yielded both. The remaining 26.3% were sterile. Infections were due chiefly to Gram positive organisms (63.6%); only 6.4% were due to Gram negative bacteria while 0.9% were due to both. Staphylococcus aureus (52.0%) was the most common isolate, followed by S epidermidis (37.2%). Pseudomonas aeruginosa and Acinetobacter calcoaceticus were the next frequent pathogens. Aspergillus was the most common fungus among the fungal isolates. The highest number of infections followed cataract extraction and keratoplasty. A vast majority of postoperative infections seem to be occurring with hospital acquired strains. Cloxacillin seems to be the most effective remedy for treating staphylococcal infections and polymyxin B for infections due to Pseudomonas. Chloramphenicol appears to be as effective as gentamicin for treating all infections.

Pathogenesis of experimentally produced corneal ulcers in rabbits.

Intracorneal injection of Staphylococcus aureus and Aspergillus fumigatus, both separately and together, produced corneal ulcer in rabbits without pretreatment of the eyes with steroids or antibiotics. Staphylococcus alone produced self-limiting ulcers. Aspergillus alone produced severe deep ulcers ending in perforations. Bacterial infection followed by introduction of fungus produced less severe ulcers than did fungus alone. Established fungal infection followed by super-imposed bacterial infection was the most severe of all. The organisms were demonstrable both in direct smear and by culture. Histopathology showed cellular infiltration by polymorphs and lymphocytes with the organisms in the corneal tissue. The pH of the eyes during the active ulcerative period remained acidic.

Comparative study of bacterial and fungal floras of contracted sockets and fellow eyes.

Through studying 50 contracted sockets, our observations showed that generalized and gross contractions were the most common. The main cause of loss of eyes was trauma. No correlation was observed between the cause of eye loss, type of surgery done, duration of eye loss, and the type of the socket. Staphylococcus aureus was the most common bacterial pathogen followed by Pseudomonas aeruginosa. Pathogens were encountered more commonly in the sockets wearing artificial eyes, a majority of which carried the same organisms. Staphylococcus epidermidis was seen most frequently in the fellow eyes. Fungal flora of the contracted sockets did not differ from that of the fellow eyes.

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.

Comparative evaluation of the enzyme immunoassay and the immunofluorescence test for the detection of chlamydial group antibodies in human sera.

The usefulness of an enzyme-linked immunosorbent assay (ELISA) in detecting chlamydial group antibodies in human sera was evaluated by comparing the results with a standard micro-immunofluorescence test (micro-IF). Of the 176 samples tested, 94.9% sera gave concordant results, 23.9% being positive and 71% negative by both the tests. ELISA detected specific antibodies in 33.3% and 13.5% sera from poultry associated and unassociated individuals respectively while corresponding figures by IF test were 36.3% and 16.2% (p less than 0.01). The IF and ELISA titres of five immune serum samples from monkeys when compared with conventional complement fixation (CF) test were found to be consistently higher. Though the two tests were found to be parallel in sensitivity and specificity (r = 0.94), IF had a marginal superiority over ELISA, while the latter could be performed more easily and read objectively.

Comparison of four serological methods for detecting antibodies to Chlamydia trachomatis.

The ability of four serological methods (enzyme-linked immunosorbent assay, single radial haemolysis, micro-immunofluorescence and complement fixation) to detect chlamydial antibodies was compared. Antigen was prepared from Chlamydia trachomatis serotype E. Sixty-two sera known to be positive and 12 negative reference sera were screened. The four tests yielded 71.6% (53/74) concordant results (Chi-square = 14.57, p less than 0.01). Samples giving discordant results had only low levels of antibodies. Analysis of results showed a strong correlation between enzyme-linked immunosorbent assay and immunofluorescence (r = 0.98), and complement fixation and single radial haemolysis (r = 0.75). Antibodies were detected in 97% of the 62 positive sera by immunofluorescence and in 91% by enzyme-linked immunosorbent assay, whereas the results for complement fixation and single radial haemolysis were only 69.3% and 70.9% respectively. Extrapolation of the regression curve to the abscissae indicated a marginal superiority of immunofluorescence over enzyme-linked immunosorbent assay, although the reading of the results of the former test was more cumbersome. Good linearity was obtained between haemolytic zone diameter and reciprocal serum dilution in single radial haemolysis. Immunofluorescence was found to be the most sensitive and complement fixation the least sensitive of the four tests.