A comparison of the iodine and fluorescent antibody methods for staining trachoma inclusions in the conjunctiva

Comparative sensitivity of fluorescent antibody staining of conjunctival scrapings and irradiated McCoy cell culture for the diagnosis of hyperendemic trachoma

The sensitivity of an indirect fluorescent antibody (FA) staining technique for detecting chlamydial inclusions in scrapings from the whole conjunctiva (upper tarsus, upper fornix, and lower lid) was compared with the sensitivity of culture in irradiated McCoy cells for the diagnosis of hyperendemic trachoma. In a group of 211 patients with various grades of active trachoma from the Bandar Abbas area of Southern Iran 42 patients were positive for chlamydiae by either method. There was little difference between the rates of positivity of FA staining of the scrapings from the whole conjunctiva (28 positives) and culture in irradiated McCoy cells (32 positives). In the patients included in this study chlamydial inclusions were detected in 15 eyes by examination of FA stained scrapings taken from the upper tarsal conjunctiva, whereas inclusions were detected in 40 eyes by the additional examination of scrapings taken from the upper fornix and lower lid (P less than 0.001). The examination of FA stained scrapings taken from the whole conjunctiva and spread as a single but larger smear may provide a satisfactory alternative to cell culture methods for the diagnosis of trachoma, particularly for field studies when cell culture facilities are not available.

Sensitivity of immunoperoxidase and immunofluorescence staining for detecting chlamydia in conjunctival scrapings and in cell culture

The sensitivities of Giemsa, immunofluorescence, and immunoperoxidase staining for the detection of Chlamydia psittaci inclusions in conjunctival scrapings and in irradiated McCoy cell monolayers were compared. Conjunctival specimens were obtained from a cat colony in which a trachoma-like disease, feline chlamydial keratoconjunctivitis, was endemic. The two immunochemical techniques were found to be of equal sensitivity and 50% to 100% more sensitive than Giemsa stain. Permanent preparations of immunoperoxidase stained material can be made and can be read using a simple light microscope. These features make the technique more useful than immunofluorescence staining, which gives temporary preparations that must be examined with a specialised fluorescence microscope.

Identification of the elementary bodies of Chlamydia trachomatis in the electron microscope by an indirect immunoferritin technique

An indirect immunoferritin (IIF) technique is described for recognizing the elementary bodies (EB) of Chlamydia trachomatis in unsectioned preparations. Both the EB of a genital strain of C. trachomatis grown in irradiated McCoy cells and EB in clinical specimens obtained from patients attending a venereal disease clinic were identified by the IIF test in the electron microscope. Cell culture-grown EB were detected by ferritin staining for up to 4 weeks after the organisms had lost their infectivity for tissue cultures. The IIF test was of comparable sensitivity to isolation methods in detecting chlamydiae in clinical specimens. Other possible applications of the IIF technique are discussed.

Cytology as a guide to the presence of chlamydial inclusions in Giemsa-stained conjunctival smears in severe endemic trachoma

Microscopical examination of 927 Giemsa-stained conjunctival smears from children with chronic trachoma in southern Tunisia showed 93 (10 per cent.) with typical trachoma (chlamydial) inclusions in epithelial cells. The accompanying cytological features were a useful indicator for inclusions. Inclusions were found only in slides with numerous polymorphonuclear neutrophils (PMNs) and separation of the epithelial cells. When these two features alone were present, 3 per cent. of the smears were inclusion-positive; when many lymphocytes were present also, 25 per cent. were inclusion positive; when other cytological features (plasma cells, macrophages, blastoid, and stem cells) were present as well, 70 per cent. of the smears were inclusion-positive. The occurrence of these sets of cytological features can be a useful guide for selecting smears for intensive examination for chlamydial inclusions. Immunofluorescent (FA) staining and Giemsa staining of 527 pairs of matched smears detected trachoma agent in 67 (13 per cent.); in thirty by both methods, in thirteen by Giemsa staining alone, and in 24 by FA alone. The examination of Giemsa-stained smears for chlamydial inclusions is a useful technique for the diagnosis of trachoma or inclusion conjunctivitis by laboratories that do not have the specialized facilities for the identification of these chlamydial infections by the technically more complex procedures of immunofluorescent staining or isolation in embryonated eggs or tissue cultures.

Serotypes of trachoma agent isolated in the Gambia: with an observation on the relation between serotype and morphology

Of 60 TRIC agents isolated from Gambian children with trachoma, 25 were serotype 1 and the remainder type 2. There was a pronounced difference in the proportions of these types in the two villages studied. In the village with a predominance of type 2 strains, TRIC agents remained confined to 2 adjacent compounds over a 14 month observation period. All 19 type 1 strains examined were characterized by the appearance in yolk sac smears of compact aggregates of elementary bodies; such aggregates were seen in only 2 of 35 type 2 strains, and may reflect a chemical difference in the surface of the elementary bodies or in a substance elaborated during their replication.

The serum and conjunctival antibody response to trachoma in Gambian children

Ninety-nine young Gambian children were studied for 61 weeks. About half of them had trachoma at the outset, and 80% of the remainder acquired the disease while under observation. IgG trachoma antibody in the serum and IgG and IgA antibodies in the conjunctival secretions (CS) were titrated by an indirect immunofluorescence method. In serum samples obtained in capillary tubes the mean titre was slightly higher than in samples collected on filter paper. Serum antibody at titres >/= 1/10 was invariably associated with a clinical diagnosis of trachoma; it increased both in frequency and titre as the disease progressed, and was present in about half of those with Tr II. In CS, IgG antibody was present less often and at lower titres than in serum, and IgA antibody was detected even less frequently. There was some evidence of correlation between the titres of IgG and IgA antibodies in CS, but none for a relationship between the titres of the antibodies in serum and those in CS. Antibodies were almost never present in the absence of conjunctival follicles, but their titres were unrelated to the degree of follicular hyperplasia; there was no obvious relationship between the serological findings and corneal lesions. In children diagnosed clinically as trachoma, serum antibody was present in almost all those with conjunctival inclusions, and in a proportion of inclusion-negative subjects; the mean titre was much higher in the inclusion-positive group.These findings do not settle whether CS antibodies are made locally, or are derived partly or wholly from the blood. They suggest that the indirect immunofluorescence test may be a useful diagnostic aid in trachoma, particularly in view of the rarity of false positive reactions; but there is at present little to choose between it and complement-fixation tests in terms of sensitivity.