Laboratory survey of Chlamydia trachomatis ocular infections

Detection of antichlamydial antibodies in tears: a diagnostic aid?

OBJECTIVES

The antibody response in sera and tears of 167 patients with suspected chlamydial conjunctivitis was compared with the antibody response in sera and tears of 45 patients with symptoms of urogenital chlamydial infection to discover whether and which type of antichlamydial antibody detected in tears may be of diagnostic help in chlamydial conjunctivitis.

METHODS

Diagnosis was based on chlamydial antigen detection from the conjunctiva and urogenital tract, done by a direct immunofluorescence assay, McCoy cell culture, and polymerase chain reaction. Additionally, antichlamydial immunoglobulin A (IgA) and immunoglobulin G (IgG) were determined in sera and tears of all patients by an immunoperoxidase assay.

RESULTS

Two hundred twelve patients were examined--167 with conjunctivitis, 45 with symptoms of urogenital chlamydial infection. Cell culture, direct immunofluorescence assay, and polymerase chain reaction brought identical results. Conjunctival specimens taken from 33 (20%) of the patients with conjunctivitis were Chlamydia antigen positive; specimens taken from 134 (80%) were negative. Antichlamydial antibodies were found in tears of 29 (88%) of the patients with conjunctivitis whose specimens were Chlamydia antigen positive. Fifty-four (40%) of the patients with conjunctivitis whose specimens were Chlamydia antigen negative had antichlamydial antibodies in their tears. Twenty-five patients with urethritis (56%) were Chlamydia antigen positive in urethral swabs; 20 (44%) were negative. Antichlamydial antibodies were found in the tears of eight (32%) of the Chlamydia antigen-positive and two (10%) of the Chlamydia antigen-negative patients with urethritis. In contrast to patients with conjunctivitis, findings for patients with urethritis always were negative for antichlamydial IgG in the tears.

CONCLUSION

Antichlamydial antibodies in tears were seen significantly more often in patients with conjunctivitis than in those with urethritis (P < or = 0.05). Antichlamydial IgG was found only in tears of patients with conjunctivitis. Therefore, the authors conclude that the detection of antichlamydial IgG in the tears might be helpful for diagnosis in patients with suspected chlamydial conjunctivitis who have antigen-negative conjunctival swabs.

Evaluation of two nonculture antigen tests and three serotests for detection of anti-chlamydial antibodies in the diagnosis of ocular chlamydial infections

BACKGROUND

Diagnosis of chlamydial conjuctivitis is difficult in chronic diseases because chlamydial elementary bodies are mostly undetectable in conjunctival scrapings by cell culture. We therefore compared two nonculture antigen tests and three different serotests for anti-chlamydial antibodies with McCoy cell culture, the "gold standard" of chlamydial diagnosis. Conjunctival scrapings and serum samples of 93 patients attending the outpatient eye clinic in Graz because of chronic follicular conjunctivitis were tested.

METHODS

A total of 558 conjunctival scrapings and 93 serum samples were investigated. Chlamydial antigen detection was done by McCoy cell culture, polymerase chain reaction (PCR; Amplicor, Roche), and direct immunofluorescence assay (DFA; Microtrak, Syva). Antichlamydial IgA and IgG antibodies in the sera were detected by an immunoperoxidase assay (IPAzyme, Savyon) and two different enzyme-linked immunosorbent assays (SeroELISA, Savyon and rELISA, medac).

RESULTS

Cell culture and PCR yielded identical results. The positivity rate for chlamydial conjunctivitis was 8.6% (8 of 93 patients). PCR proved most sensitive and most specific. IPAzyme was 75% sensitive for IgA and 100% for IgG; SeroELISA and rELISA were less sensitive. IPAzyme was 81% specific for IgA and 47.3% for IgG. SeroELISA and rELISA were less specific for IgA, but more specific for IgG. Post-test likelihood of disease was greatest in IPAzyme.

CONCLUSIONS

PCR proved to be a good alternative to cell culture; DFA is useful for quick diagnosis. Genus-specific serotests cannot compete with chlamydial antigen detection. They differ in sensitivity and specificity because of the antigen type they present. They are still of only supportive value in cases where chlamydial antigen detection is not possible. Recently introduced species-specific antibody tests should be of greater value.

The treatment and follow up of adult chlamydial ophthalmia

Sixty two patients diagnosed as having adult chlamydial ophthalmia were treated with oral doxycycline and roxithromycin in association and tetracycline eye wash for 2 weeks. Chlamydial ophthalmia was diagnosed by laboratory detection of the micro-organism in ocular specimens using direct immunofluorescent monoclonal antibody staining for Chlamydia trachomatis, chlamydial culture in cycloheximide treated McCoy cells, and Giemsa staining. An immunoenzymatic method for detection of specific IgG and IgA in patients' serum was used as an additional test to confirm the diagnosis. All patients were reexamined 3 weeks after completing their course of antibiotics and in the case of persistent infection a further course of treatment was given. With this treatment regimen 48 out of 62 patients (77.4%) were cured after three courses. Because of the risks of an inadequate response to therapy, we recommend a proper post-treatment follow up in all patients with chlamydial eye infections.