Detection of experimental Chlamydia trachomatis eye infection in conjunctival smears and in tissue culture by use of fluorescein-conjugated monoclonal antibody

Trachoma

Trachoma is a keratoconjunctivitis caused by ocular infection with Chlamydia trachomatis. Repeated or persistent episodes lead to increasingly severe inflammation that can progress to scarring of the upper tarsal conjunctiva. Trichiasis develops when scarring distorts the upper eyelid sufficiently to cause one or more lashes to abrade the cornea, scarring it in turn and causing blindness. Active trachoma affects an estimated 84 million people; another 7.6 million have end-stage disease, of which about 1.3 million are blind. Trachoma should stand on the brink of extinction thanks to a 1998 initiative launched by WHO--the Global Elimination of Trachoma by 2020. This programme advocates control of trachoma at the community level with four inter-related population-health initiatives that form the SAFE strategy: surgery for trichiasis, antibiotics for active trachoma, facial cleanliness, and environmental improvement. Evidence supports the effectiveness of this approach, and if current world efforts continue, blinding trachoma will indeed be eliminated by 2020.

Nucleic acid amplification tests for gonorrhea and chlamydia: practice and applications

Nucleic acid amplification tests (NAATs), which are highly sensitive and specific, have provided the ability to use alternative sam-ple types for the diagnosis of sexually transmitted infections (STIs). Self-collected genital specimens, such as urine or even vaginal swabs, can now be accurately used to diagnose gonorrhea or chlamydia infections. In many cases, use of these sample types can decrease the necessity for a clinician to perform a pelvic examination on women or to collect a urethral swab from men, thus extending the diagnostic capability for detecting these infections to nonclinic screening venues. As most chlamydia infections and many gonorrhea infections are asymptomatic, the use of NAATs for self-collected samples greatly increases the types and numbers of patients that can be screened outside of clinic settings. Self-sampling also allows clinicians to easily screen patients in the clinic for STIs who are not presenting for pelvic or urogenital examinations. The application of NAATs to self-collected specimens has the potential to augment public health programs designed to control the epidemic of STIs in the community.

Clinical examination and laboratory tests for estimation of trachoma prevalence in a remote setting: what are they really telling us?

Worldwide, an estimated 84 million people have active trachoma and 7.6 million people have trachomatous trichiasis. WHO's SAFE strategy is an effective tool in the worldwide effort to eliminate blinding trachoma, but its institution and monitoring requires a simple, reliable, and cost-effective method to detect disease. To date, clinical examination has provided the main method of diagnosis. Detection of Chlamydia trachomatis with nucleic acid amplification tests does not always correlate well with clinical findings, which has prompted the suggestion that these methods should replace clinical examination. However, a review of the research carried out in animals and human beings suggests the relation between laboratory tests and clinical examination is due to the kinetics of trachoma and not to an inherent problem in either detection system. Given the increased difficulties of using laboratory tests in parts of the world where trachoma is endemic, we should not abandon clinical grading as a tool to assess the need for, and the effectiveness of, trachoma intervention programmes.

Urine nucleic acid amplification tests for the diagnosis of sexually transmitted infections in clinical practice

PURPOSE OF REVIEW

With the advent of highly sensitive and specific nucleic acid amplification assays, this report will demonstrate that self-collected genital specimens, such as urine or even vaginal swabs can be accurately used to diagnose sexually transmitted infections.

RECENT FINDINGS

Use of self collected samples can eliminate the necessity of a clinician to perform a pelvic examination for women or collect a urethral swab for men, thus extending the diagnostic capability for sexually transmitted infections to non-clinic screening venues. As many sexually transmitted infections are asymptomatic, this ability to use self-sampling greatly increases the numbers of patients that can be screened, and has the potential to augment public health programs designed to control the epidemic of sexually transmitted infections in the community. Patient collected samples are highly acceptable, highly accurate, and are becoming widely used. Self-sampling also allows clinicians to easily screen patients in the clinic, who are not presenting for pelvic or urogenital examinations, for sexually transmitted infections.

SUMMARY

Highly accurate molecular tests and easily obtained self-collected urogenital samples represent the ideal combination for obtaining the public health goal of decreasing the sexually transmitted infection epidemic among sexually active persons in the United States today.

The Use of Urine and Self-obtained Vaginal Swabs for the Diagnosis of Sexually Transmitted Diseases

Studies have reported that self-collected specimens, such as urine or vaginal swabs, can be successfully used to diagnose sexually transmitted infections when they are used with nucleic acid amplification assays. This eliminates the necessity for a clinician-performed pelvic examination for women, or a urethral swab for men, for sample collection. These nucleic acid amplification assays used with self-collected specimens are highly sensitive and specific, and their use may be extended to broad nonclinic screening venues, where their use can augment public health programs designed to control the epidemic of sexually transmitted diseases.

Ultrastructural and molecular analyses of the persistence of Chlamydia trachomatis (serovar K) in human monocytes

Previous studies have suggested that monocytes may play a role in the dissemination of Chlamydia trachomatis, and in establishment of persistent infection with this bacterium. Infection of cultured human peripheral blood monocytes with C. trachomatis serovar K produced persistent, nonproductive infection. Transmission electron microscopy of such infected cultures revealed single or multiple Chlamydia in monocyte inclusions over a culture period of 10 days. Those inclusions were aberrant, and normal reticulate bodies within the inclusions were not observed. Immunoelectron microscopy showed the chlamydial major outer membrane protein and lipopolysaccharide to be associated with the bacterial plasma membrane. Lipopolysaccharide was also identified in the monocyte cytoplasm. Molecular analyses of primary chlamydial rRNA transcripts demonstrated that the organism is viable and metabolically active within monocyte inclusions. However, attempts to overcome chlamydial growth arrest by incubation of Chlamydia-infected monocytes with tryptophan, and antibodies against alpha interferon, gamma interferon, or tumor necrosis factor, were all ineffective, suggesting that known mechanisms of growth inhibition do not hold in human monocytes. These observations indicate that infection of human peripheral blood monocytes with C. trachomatis may be involved in the genesis/maintenance of extra-urogenital inflammation, since non-culturable, metabolically active bacteria persist in those cells.

Oral immunization with an anti-idiotypic antibody to the exoglycolipid antigen protects against experimental Chlamydia trachomatis infection

Chlamydia trachomatis is the leading cause worldwide of preventable infectious blindness (trachoma) and sexually transmitted disease, including nongonoccocal urethritis and pelvic inflammatory disease. To date, no effective vaccine against C. trachomatis infection has been identified. A monoclonal anti-idiotypic antibody (anti-Id) to the chlamydial exoglycolipid antigen (GLXA) was tested in a murine model of ocular chlamydial infection for its ability to induce systemic immunity, which reduces microbiologic and clinical disease. The anti-Id to GLXA, delivered either systemically in soluble form or orally after encapsulation in poly(lactide) microspheres, induced significant protective immunity against ocular challenge of mice with a human biovar of C. trachomatis. Protection was associated with induction of anti-GLXA antibody and anti-chlamydial neutralizing antibody.

[Analysis of direct immunofluorescence tests for trachoma diagnosis]

For the confirmation of trachoma foci in places where no previous cases had been reported, the State Health Secretariat of S. Paulo makes provision for the realization of laboratory exams, particularly because the disease was considered to have been eradicated from the State in the seventies. During the epidemiological investigations, conjunctival scrapings were collected from the subjects with inflammatory trachoma (TF/TI), clinically diagnosed. The results of the immunofluorescence (DFA) exams were analysed in the light of the frequency of the appropriate exams and their positive results, by the quantity of elementary bodies (EB) found. A total of 385 slides were studied, the criteria for positivity being 5 or more EBs. The test's sensitivity was 19.9%. The DFA test is considered to be the best laboratorial exam to be used in field work, though it does not show a sufficient sensitivity to confirm all clinically diagnosed cases of trachoma; it can only confirm the circulation of the aetiological agent within a community. In endemic areas the clinical diagnosis continues to be the criterion for case confirmation.

Case report: in situ hybridization for detection of inapparent infection with Chlamydia trachomatis in synovial tissue of a patient with Reiter's syndrome

The authors have shown that protein antigens, RNA, and DNA from Chlamydia trachomatis are present in synovial tissues of patients with Reiter's syndrome (RS). However, those studies gave no insight into the host cell type involved or the precise tissue location of the bacteria. To address such issues, the authors developed an in situ hybridization system to detect chlamydia, and they used that system to examine synovial biopsies from a patient with RS and a patient without RS. The in situ system uses a previously described digoxigenin-labeled DNA probe that hybridizes with chlamydial 16S rRNA sequences in paraformaldehyde-fixed samples. Control studies with chlamydia-infected and uninfected HeLa cells confirmed that the in situ system is as sensitive as is direct fluorescence cytology for detection of the organism. Morphology of host and chlamydia cells is preserved after hybridization. Studies using synovial tissue from an osteoarthritis patient produced no in situ hybridization signal, but similar hybridization to tissue from a culture-/direct fluorescence cytology- negative RS patient had a strong intracellular signal for chlamydia within a subsynovial cell layer. These in situ hybridization results confirm the extensive presence of chlamydia in synovia and extend the authors' earlier observation that chlamydia RNA is present in the synovia of patients with RS. The data also confirm their electron microscopy studies, indicating that chlamydia are intracellular in synovial tissue, and they further show that infected host cells are located beneath the synovial lining.

Intracellular location of inapparently infecting Chlamydia in synovial tissue from patients with Reiter's syndrome

Culture of Chlamydia trachomatis from synovial tissues/fluids from Reiter's syndrome (RS) patients frequently yields negative results. However, we have identified chlamydial RNA at that site in such patients, suggesting that viable organisms may be present. Here we define the cellular location of chlamydia within the synovium via in situ hybridization. Using a chlamydial ribosomal RNA-directed probe, we show that synovial tissue from culture-negative RS patients gives strong hybridization which is often localized to a subsynovial cell layer, rather than to the synovial lining; in some cases, hybridizing cells are dispersed through the synovium. All hybridization signal is located within host cells, indicating that infectious extracellular elementary bodies are rare or absent. These data confirm the extensive intracellular presence of inapparent chlamydia in the synovia of RS patients and provide some insight into the usual culture negativity of synovial tissues for the organism.

Inapparent ocular infection by Chlamydia trachomatis in experimental and human trachoma

There is substantial indirect evidence which suggests that Chlamydia trachomatis can generate inapparent, persistent infections in human. To confirm this directly, we examined ocular chlamydial infection in both the cynomolgus monkey model of trachoma and in patient samples from a trachoma-endemic area. In monkeys, ocular infection was studied over time using direct immunofluorescence cytology (DFA) and a molecular hybridization screening system which targets chlamydial ribosomal RNA. In eleven animals infected once with B serovar, DFA and probe screening of parallel conjunctival swabs gave congruent results through day 42 post-infection. Thereafter, DFA showed clearing of chlamydia and was negative by day 70, as in previous studies. In contrast, hybridization analysis indicated a continuing presence of chlamydial RNA in all samples from all animals through the end of the experiment at day 84 post-infection. Similarly, analysis of swabs from trachoma patients showed that a number of DFA-negative samples gave clear positive signal for chlamydial RNA. Taken together these data indicate that ocular chlamydial infection persists for longer periods than previously thought, judging solely on the basis of DFA, and they support the idea that inapparent ocular chlamydial infection occurs in vivo.

Recurrent arthritis in Reiter's syndrome: a function of inapparent chlamydial infection of the synovium?

Present or prior infection with any of several common bacterial pathogens has been strongly implicated in the development of Reiter's syndrome (RS). However, because Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen in the western hemisphere, this organism has emerged as a major causative agent of the disease. An important but as yet poorly understood aspect of chlamydia-related RS is the recurrence of active arthritis in the absence of any overt infection or reinfection with the organism. In this article, a large body of published clinical and experimental observations strongly suggesting that some chlamydial infections in humans can be inapparent--not detectable by standard culture or antibody-based laboratory screening methods--is reviewed. The authors' own initial molecular genetic studies, which support that contention, are summarized. Based on these data, the argument is developed that not only does inapparent chlamydial infection occur in humans, but such infections may have significant consequences in terms of the pathogenesis of RS, including the possible causation of recurrent episodes of disease in the absence of active infection. The therapeutic implications of potential inapparent chlamydial infections as they relate to RS are discussed.

RNA-directed molecular hybridization screening: evidence for inapparent chlamydial infection

Both clinical and epidemiological data suggest that inapparent infection by Chlamydia trachomatis occurs in humans. To confirm and study such infections, we developed a hybridization screening system directed toward chlamydial ribosomal RNA (rRNA). Six restriction endonuclease fragments derived from the cloned rrnA operon of chlamydial serovar L2(434) were tested as hybridization screening probes, but only one fragment encoding the 5' portion of the 16s rRNA gene plus some upstream flanking sequence was both sensitive and highly specific in such experiments. In Northern slot blot assays, hybridization analyses with this fragment as probe routinely detected one picogram or less of chlamydial RNA when that RNA was bound to membranes alone or as part of a mixture with a vast excess of mammalian RNA. The probe did not hybridize to RNA from mammalian and relevant bacterial sources but did hybridize to rRNA from B (ocular) and E (genital) serovars of C. trachomatis. Experiments using RNA from conjunctival biopsies and standard conjunctival swab samples from cynomolgus monkeys showed that the probe reliably distinguishes between known chlamydia-infected and uninfected samples. This suggests that it may be useful for clinical screening. Characterization assays for the RNA-directed probe screening system in this monkey model of trachoma provide initial molecular evidence that ocular chlamydial infection may persist longer than previously thought, based solely on direct fluorescence antibody assay (DFA) and culture analyses.

T cells and trachoma. Their role in cicatricial disease

Frozen sections of tarsoconjunctival biopsies with trachomatous scarring from 14 black adults undergoing corrective surgery for trichiasis, and "normal" tissue from three postmortem controls, were immunohistochemically stained for the major T- and B-cell subsets, and for macrophages and monocytes. T cells outnumbered B cells by 2 to 17 times, and macrophages and monocytes by approximately 20 times in all specimens. Biopsies were categorized as "inflamed" if a cumulative inflammatory score of cellular staining in the substantia propria with CD4, CD8, and OKM1 monoclonal antibodies was greater than that of control tissues. CD4+ lymphocytes predominated over CD8+ lymphocytes in 5 of 7 inflamed biopsies, whereas CD8+ lymphocytes predominated over CD4+ lymphocytes in 5 of 7 noninflamed biopsies. Lymphoid aggregates were present in five inflamed biopsies, but lacked germinal centers, centrally located B cells, or parafollicular T cells typical of the acute stage of trachoma. CD4+ and CD8+ lymphocytes also were observed in the epithelium and lumen of Meibomian glands. These observations indicate that the inflammatory infiltrate of the tarsoconjunctiva in the cicatricial stage of trachoma is comprised predominantly of T cells, and suggests that T cells may be involved in the genesis of tarsal thickening and conjunctival scarring seen in the later stages of trachoma.

Laboratory survey of Chlamydia trachomatis ocular infections

The authors used immunofluorescence and immunoperoxidase tests to study a group of 101 patients with acute or chronic conjunctivitis, etiologically unrelated to conventional bacterial pathogens, and a control group of 30 healthy adults. Positive titers of IgG in serum and of IgA in lacrimal secretions against Chlamydia, detected by IPA, correlated with the identification of microorganisms by direct immunofluorescence. The use of both tests allows a precise evaluation of the stage of the infection and of its evolutive pattern.

A polymerase chain reaction (PCR) protocol for the specific detection of Chlamydia spp

The polymerase chain reaction is an in vitro procedure for primer-directed enzymatic amplification of specific template nucleic acid sequences. This technique was used to detect and differentiate Chlamydia trachomatis and Chlamydia psittaci in laboratory samples of infected McCoy cells. The polymerase chain reaction was shown to be both sensitive, detecting in the order of one chlamydial DNA molecule in 10(5) cells, and specific. No cross reaction (amplified product) was detected when a variety of mammalian cell and bacterial DNAs were used as template with the Chlamydia-specific oligonucleotide primers.

Lymphogranuloma venereum conjunctivitis with a marginal corneal perforation

The authors have recently treated a case of Parinaud's oculoglandular syndrome due to Chlamydia trachomatis serotype L2, a causative agent of lymphogranuloma venereum (LGV). The ocular manifestations included a mixed papillary-follicular conjunctivitis with fleshy superior limbal lesions in both eyes. A superior marginal corneal perforation requiring a therapeutic corneal graft was present in the right eye. The patient had vaginitis, inguinal lymphadenopathy, a history of Sjögren's syndrome, and seropositivity to human immunodeficiency virus (HIV). The ocular disease resolved completely after 6 weeks of oral tetracycline therapy.

Immunodiagnosis of adult chlamydial conjunctivitis

This study presents data from a prospective comparison of four currently available diagnostic tests for Chlamydia trachomatis infection. Seventy-six patients clinically suspicious for chlamydial conjunctivitis were all tested with Giemsa stain cytology, direct monoclonal fluorescent antibody (DFA) microscopy, enzyme immunosorbent assay (EIA) for chlamydial antigens, and standard McCoy cell culture. When compared with primary cell culture, diagnostic Giemsa inclusions had a sensitivity and specificity of 43 and 100%, respectively, supportive Giemsa cytology 71 and 67%, the enzyme immunoassay 71 and 97%, and the monoclonal fluorescent antibody 57 and 81%. Each nonculture method has distinct advantages in terms of cost, technical difficulty, speed, and accuracy, which dictate selection of the most appropriate test for office or laboratory diagnosis of chlamydial conjunctivitis.

Absence of Chlamydia in trachomatous lacrimal sacs

We performed lacrimal sac biopsies in 35 patients who underwent dacryocystohinostomies in Saudi Arabia. The nasolacrimal duct obstructions were presumably secondary to trachoma in 22 cases and unknown in the remaining 13 cases. Lacrimal sac specimens were submitted for routine histopathologic examination and the direct-smear fluorescent antibody test. All specimens were negative for chlamydia. Possible reasons for the low detection rate of chlamydia in the trachomatous group were the frequent finding of clinically inactive disease, common canalicular obstruction, and loss of the epithelial lining in the lacrimal sac.

The diagnosis and treatment of chlamydial conjunctivitis

Chlamydial conjunctivitis will usually go unrecognized and therefore untreated unless it is specifically considered. The possibility of chlamydial infection must be borne in mind in neonatal conjunctivitis, in acute conjunctivitis in sexually active adults, and in chronic follicular conjunctivitis. Chlamydial conjunctivitis is often indistinguishable from other forms of conjunctivitis on clinical grounds, and accurate diagnosis is based on laboratory tests. It seems that direct fluorescent antibody (DFA) cytology offers an attractive alternative to the more complicated and time-consuming tissue culture isolation method. Once diagnosed, chlamydial infection should be treated with the appropriate systemic antibiotics, and proper posttreatment follow-up is necessary to assess the efficacy of treatment.

Monoclonal antibodies in the laboratory diagnosis of trachoma

Various techniques which use monoclonal antibodies to detect Chlamydia trachomatis in clinical specimens are reviewed. An investigation comparing the efficacy of immunofluorescent staining with Giemsa staining in detecting Chlamydia in conjunctival scrapings from cases of active trachoma is presented. Sixty-two eyes of schoolboys with moderate to severe trachoma were studied. Giemsa staining detected chlamydial inclusion bodies in 34 percent of the specimens. Free elementary bodies were detected by fluorescent monoclonal antibody in 21 percent. Eleven percent were positive by both Giemsa and immunofluorescence and 55 percent were positive by either Giemsa and/or immunofluorescence. The addition of fluorescent monoclonal antibody assay to routine Giemsa staining resulted in an increase in the yield of positive specimens by 29 percent.

The effect of cyclosporine in chlamydial eye infection

The effect of cyclosporine (CsA) treatment in both primary and secondary Chlamydia trachomatis ocular infection in cynomolgus monkeys was studied. Following primary infection, CsA-treated animals developed severe clinical symptoms which persisted for up to 12 weeks compared to control animals which developed less severe inflammation lasting only 4 to 6 weeks. CsA treatment had no effect on the clinical course of a second ocular infection. Antigen-specific antibodies developed normally in the serum and tears of all animals, but the titer of IgM in serum and secreted IgA in tears of CsA-treated animals was significantly lower than control animals. Chlamydia-specific cell-mediated immunity, as determined by in vitro lymphoproliferation assays of peripheral blood, did not develop in either group of animals.

Evaluation of diagnostic tools for adult chlamydial keratoconjunctivitis

Conjunctival smears and serum specimens of 150 patients with presumed chlamydial keratoconjunctivitis were evaluated over a period of 16 months and compared to age- and sex-matched healthy controls. Sensitivity, specificity, and predictive values of fluorescent monoclonal antibody (FMAb) direct tests, IgG single antigen tests for the detection of serum antibody (IgG-IFT), and IgA and IgG immunoperoxidase tests (IgA-IPAs and IgG-IPAs) for serum antibody were compared to McCoy cell culture techniques in a nonoptimized clinical setting. Thus, FMAb sensitivity was 100%, specificity was 52%, and predictive value was 30%. IgG-IFT sensitivity was 94%, specificity was 67%, and predictive value was 37%. IgA-IPA sensitivity was 100%, specificity was 70%, and predictive value was 40%. The IgG-IPA was sensitive but nonspecific. With respect to the current epidemiologic situation in our area, FMAb and IgA-IPA in addition to McCoy cell culture techniques may represent valuable diagnostic tools for the detection of chlamydial disease.

A microbiological study of conjunctivitis with emphasis on Chlamydia trachomatis, in northern Norway

To determine the microbiological agents in conjunctivitis in children and young adults, physicians outside hospitals were asked to obtain samples from the conjunctiva in patients presenting with conjunctivitis. Specimens from 194 patients and 177 healthy controls were cultivated for Chlamydia trachomatis. In 12 cases Chlamydia trachomatis was isolated (i.e. 4 neonates, 1 three-year-old child and 7 adults, aged 17 to 39 years), but in none of the controls. Of the specimens from patients 168 and all of the healthy controls were cultivated for both bacteria (including Chlamydia trachomatis) and viruses. The main micro-organisms, regarded as infectious, were Haemophilus influenzae (20), Streptococcus pneumoniae (18), Staphylococcus aureus (14) and Chlamydia trachomatis (9). Haemophilus influenzae (non-typable strains) were isolated more frequently in the age group below 5 years of age than in the age group 5-50 years. Herpes simplex virus (type II) was isolated in one neonate. Chlamydia trachomatis is among the most important infectious agents in conjunctivitis treated outside hospitals. As chlamydial infections need special attention regarding treatment and follow-up, physicians should be encouraged to obtain specimens for microbiological examination, including chlamydia, from the population at risk.

The detection of Chlamydia trachomatis by direct immunofluorescence in conjunctival smears from patients with trachoma and patients with ophthalmia neonatorum using a conjugated monoclonal antibody

Duplicate specimens were taken with cotton-wool swabs from the upper tarsal conjunctiva of 63 patients living in Gambian villages in which trachoma is endemic and from 34 infants with ophthalmia neonatorum (ON) attending an outpatient clinic in The Gambia. The detection of Chlamydia trachomatis by direct immunofluorescence (IF) using a conjugated monoclonal antibody to its principal outer membrane protein was compared with isolation in cycloheximide-treated McCoy cells. For trachoma, the sensitivity and specificity of the immunofluorescent technique were 62% and 100% respectively if ten elementary bodies (EBs) was taken as the minimum requirement for positivity by IF. If all cases with one or more EB were considered positive, the sensitivity was 81% and the specificity 85%. For ON the sensitivity and specificity were 100% and 95% respectively, regardless of which criterion was used. In view of its simplicity and easy applicability to field conditions it seems likely that direct IF using monoclonal antibodies may be a useful technique for the detection of C. trachomatis in the conjunctival epithelium of patients with trachoma.

Chlamydial infections

Chlamydiae are small bacteria that have a unique life cycle. There are two species, Chlamydia psittaci and C. trachomatis, which cause a wide spectrum of clinical disease, including neonatal conjunctivitis and pneumonia, sexually transmitted disease, psittacosis, and trachoma. The importance of chlamydial disease in public health is being increasingly recognized, and the incidence in developed countries seems to be increasing. An understanding of chlamydial disease, its prevention and treatment, is essential for the infection control practitioner, who can play a significant role in patient education.