Agent Of Trachoma Research Articles

Chlamydial urethral infection in Teheran. A study of male patients attending an STD clinic.

The prevalence of chlamydial infection of the urethra was studied in 172 consecutive male patients attending a sexually transmitted disease clinic in Teheran. Chlamydia trachomatis was isolated in 8.8% of the patients with a valid culture result. Of the five isolates serotyped, two were serotype E and three were serotypes G, H, and K. Type-specific antibodies against C trachomatis serotypes D to K were found in 16% of patients, and IgM, indicating current infection, was detected in 12%. Type-specific antibodies against serotypes A to C (trachoma agent) were detected in 5.4%. The low chlamydial isolation rate may have been due to the inclusion of a large number of patients with a mild or trivial urethritis or a history of previous treatment with antichlamydial drugs. The results indicate that in Iran where trachoma is still endemic, chlamydial infection of the urethra does occur in the urban population and is caused by serotypes D to K.

Structural studies of the outer envelope of Chlamydia trachomatis by electron microscopy

Electron microscopic observations have been made on the outer cell envelopes of Chlamydia trachomatis, the agent of trachoma. It has been shown that they contain a hexagonal lattice with a unit cell of about 17·5 nm. Computer processing has been carried out on the hexagonal array and on ring-like particles occurring in fragmented envelopes. The structure of these rings can be related to the distribution of material in a three-dimensional model obtained for the hexagonal lattice. This model has been compared with biochemical data for the cell envelopes.

Expression in E. coli of Chlamydia trachomatis antigen recognized during human infection.

Chlamydia trachomatis, a prokaryotic obligate intracellular parasite of eukaryotic cells, has long been recognized as the agent of trachoma, the major infectious cause of human blindness1. In the past decade, clinical investigations have shown that the frequency and severity of chlamydial genital infection parallels that of gonorrhoea, and that C. trachomatis is a major cause of non-gonococcal urethritis, epidymitis, proctitis, cervicitis and salpingitis, as well as conjunctivitis and pneumonia in neonates2. Despite the new awareness of its role in human disease, there is a need for improved methods of identification and control of C. trachomatis infections. Progress in these areas awaits a more detailed understanding of the pathogenesis of chlamydial infection, including definition of key antigenic structures recognized in human disease. We have studied the immune response to chlamydial polypeptides during human infection and have found that most infected patients have antibody to polypeptides of molecular weight (Mr) 67,000 (67K), 60K, 40K, 19K and 16K, regardless of infecting immunotype3. We report here the cloning and expression in Escherichia coli of the 19K C. trachomatis polypeptide, an immunogen in human chlamydial infection.

Chlamydial Infections

Chlamydia trachomatis was first described by Halberstadter and Von Prowazek in 1907, as a characteristic intracytoplasmic inclusion in the conjunctival scrapings from a patient with trachoma. Although the organism was identified as the etiologic agent of trachoma and inclusion conjunctivitis in the neonate, a full understanding of its nature was not feasible until C trachomatis was first successfully propagated in cell cultune in 1965. This technical innovation greatly facilitated investigation of the biology and the epidemiology of chlamydial infections in man. C trachomatis is now recognized to be one of the most prevalent sexually transmitted diseases in the United States today. It is responsible for 40% to 50% of cases of nongonococcal urethritis (NGU) in men and a large reservoir of genital infection, largely asymptomatic, in women. In the United Kingdom, where NGU is a reportable disease, NGU is now more prevalent than gonorrhea and is considered to be the most important male veneral disease. The cervical infection in women is of special importance to pediatricians as the infection may be transmitted to the infant during parturition, leading to both ocular and respiratory disease. A thorough understanding of the microbiology and epidemiology of C trachomatis is an important prerequisite for appreciating the clinical features, diagnostic methods, and management of these infections by pediatricians.

Cytological diagnosis of virus-infected cells in Papanicolaou smears and its application in clinical practice.

The cytopathic changes of herpes simplex virus, varicella-zoster virus, the human polyomaviruses, and the trachoma agent can be recognised in smears prepared from a wide variety of specimens. The morphology of virus-infected cells is described, and the clinical value of these observations is discussed. Cytological diagnosis offers a rapid and convenient method of detecting infection with these viruses which can be confirmed by conventional virological method while the patient is still in the acute stages of the disease. Confirmation can also be made retrospectively by reprocessing cells, identified in the Papanicolaou smear, for electron microscopy. Screening for virus-infected cells in cytological smears is a technique that can be developed in any pathology laboratory prepared to provide a comprehensive cytology service, and it is proving to be a useful tool in clinical diagnosis and applied research.

Impermeability of human cells to silver sulphadiazine: a biological experiment

Summary Silver sulphadiazine, an effective antimicrobial agent, does not block the development of intracellular trachoma agent. Sodium sulphadiazine, on the other hand, inhibits the developmental cycle of this agent. The results are taken to indicate that silver sulphadiazine cannot penetrate into the intact mammalian cell. This greatly reduces the remote possibility that this agent is able to interact with the cellular DNA and thereby induce genetic and carcinogenic changes.

The Agent of Trachoma: Recent Studies on the Biology, Biochemistry and Immunology of a Prokaryotic Obligate Parasite of Eukaryocytes

Medical Journal of AustraliaVolume 2, Issue 19 p. 728-728 Book Reviews The Agent of Trachoma: Recent Studies on the Biology, Biochemistry and Immunology of a Prokaryotic Obligate Parasite of Eukaryocytes Doris M. Graham, Doris M. GrahamSearch for more papers by this author Doris M. Graham, Doris M. GrahamSearch for more papers by this author First published: 01 November 1976 https://doi.org/10.5694/j.1326-5377.1976.tb128249.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume2, Issue19November 1976Pages 728-728 RelatedInformation

A Search For Mycoplasmas And Chlamydiae In Acne Lesions

No mycoplasmas and no chlamydiae were found in cultures of 75 uninflamed comedones, 72 papulopustular lesions, and 7 cystic lesions from 14 subjects with acne. Chlamydial serologic tests were negative for 11 subjects and showed antibodies in 3 subjects to 3 different antigenic types of trachoma agent. These results are viewed as substantial evidence against the possibility that either mycoplasmas or chlamydiae play an important part in the pathogenesis of acne.

Monographs in Virology: The Agent of Trachoma

This scholarly monograph covers the molecular biology of the trachoma agent and related<i>Chlamydia</i>, with respect to their classification, isolation, animal infectivity, morphology, chemical composition, enzymatic activities, antigenic composition, protein synthesis, immunobiology, and antibiotic responses. It is a useful reference source for workers in trachomatology and microbiology.

Trachoma in the Sudan. A laboratory study.

Out of 46 patients in the Sudan who had been diagnosed clinically as having trachoma 25 strains of the trachoma agent were isolated. Bacterial contamination was easily controlled by streptomycin and vancomycin. On repeated passaging, chick embryos lost their susceptibility to the trachoma agent during the summer.

Topical Tetracycline and Rifampicin Therapy of Endemic Trachoma in Tunisia

A controlled chemotherapy trial of trachoma was carried out in a Tunisian oasis among schoolchildren with active disease. We compared 1% tetracycline ointment (79 patients) or 1% rifampicin ointment (76 patients) with 5% boric acid ointment (79 patients). Medications were administered twice daily, six days a week, for ten weeks. Slit-lamp examinations by three ophthalmologists were made independently before treatment as well as five, 19, and 39 weeks after treatment. Bacteriologic cultures were taken during treatment as were smears to detect trachoma agent at each clinical examination. Five weeks after treatment, the intensity of conjunctival disease in the tetracycline and rifampicin groups was reduced significantly when compared with boric acid, but at 19 weeks this suppression was found only in the tetracycline group. Ocular bacterial pathogens were eliminated almost entirely in the two antibiotic groups during treatment. The initial prevalence of trachoma (29to 31%) was significantly reduced in the two antibiotic-treated groups at five weeks and 19 weeks after treatment. The prevalence of trachoma was equally low (7%) in all three groups following retreatment with tetracycline. Although both antibiotics were effective, rifampicin offered no advantage over tetracycline in this trial. Recurrent disease in this school-based treatment study probably was due to reinfection from younger siblings at home. While systematic, community-wide, antibiotic treatment programs are not always possible in countries where trachoma is endemic, limited antibiotic therapy programs should be continued in these areas to reduce the intensity and prevalence of trachoma, even though the disease cannot be eradicated.

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.

SIMPLIFIED METHOD FOR DIAGNOSIS OF GENITAL AND OCULAR INFECTIONS WITH CHLAMYDIA

The diagnosis of infections with chlamydia related to the trachoma agent is best confirmed by isolation of the organism in tissue-culture. A simplified technique using conventional monolayers of McCoy cells can be used as an alternative to current methods involving heavily irradiated cells and appears to be of reasonable sensitivity. Chlamydial infection was confirmed in 38/190 females attending venereal clinics, in 22/35 patients with hypertrophic cervical erosions, and in 7/18 infants with ophthalmia neonatorum.

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.

Isolation of Chlamydia trachomatis by Use of 5-Iodo-2-Deoxyuridine—Treated Cells

Irradiated McCoy cells have provided a useful technique for the isolation of Chlamydia trachomatis strains, among which are found the etiological agents of trachoma, inclusion conjunctivitis, and lymphogranuloma venereum. Because irradiation is not always readily available, 5-iodo-2-deoxyuridine (IUDR) treatment of cells was investigated as a substitute procedure. IUDR-treated cells were found to be as sensitive to C. trachomatis infection as were irradiated McCoy cells. Stock chlamydial strains gave similar titers of iodine-stained inclusions in either system. When cells treated with IUDR were compared with irradiated cells for the isolation of C. trachomatis from clinical specimens, 5 of 138 specimens yielded isolates in IUDR-treated cells not found in irradiated ones, and one isolate was obtained from irradiated but not from IUDR-treated cells. In those 56 cases where inclusions were seen in both systems, there were significantly more inclusions in IUDR-treated than in irradiated cells. Although this series of cultures is too small to determine whether IUDR-treated cells are superior to irradiated ones for the isolation of C. trachomatis, the data indicate that IUDR treatment is at least equally effective.

Studies on the developmental cycle of Chlamydia trachomatis: selective inhibition by hydroxyurea.

Hydroxyurea, a potent inhibitor of deoxyribonucleic acid synthesis, inhibits the development of trachoma agent when applied at a concentration of 5 x 10(-2) M. At a lower concentration, 5 x 10(-4) M, hydroxyurea permits the development of the trachoma inclusion bodies and initial bodies, but arrests the formation of elementary bodies, the infectious entity of the agent. The inhibitory effect of 5 x 10(-4) M hydroxyurea is reversible and can be used to synchronize the development of the agent. The synthesis of deoxyribonucleic acid, ribonucleic acid, and proteins takes place in the initial bodies after the removal of the inhibitor.

Studies on the developmental cycle of Chlamydia trachomatis: isolation and characterization of the initial bodies.

The initial bodies which develop in the inclusion bodies of trachoma agent (Chlamydia trachomatis) were separated from the infected cells nuclei and cytoplasmic components by zone centrifugation in sucrose gradients. The initial bodies are the site of the agent's ribonucleic acid synthesis and serve as precursors to the elementary bodies. The conversion of the initial bodies to elementary bodies is through a process which resembles binary fission. The effects of antibiotics on the development of the trachoma agent initial bodies revealed that rifampin prevented and hydroxyurea affected the formation of the initial bodies. Penicillin led to the formation of structures larger than the initial bodies.

Immunity to chlamydial infections of the eye. V. Passive transfer of antitrachoma antibodies to owl monkeys.

Previous studies have shown that owl monkeys which have had a trachoma agent infection were subsequently highly resistant to challenge by both homologous and heterologous organisms. In the present study, passive transfer of owl monkey serum containing antitrachoma antibody from immune monkeys did not protect recipient monkeys from infectious challenge with homologous trachoma. Antibody was not detectable in eye secretions of the recipient monkeys until the intensity of infection was waning, suggesting but not proving that local antibody synthesis rather than simple transudation of serum antibody occurs.

Effect of rifampicin on the development of tumours induced by adenovirus in male hamsters.

INITIAL in vitro studies established that rifampicin, one of a group of rifamycin SV derivatives1,2, prohibits bacterial growth and phage replication by binding to a polypeptide component of the microbial DNA-dependent RNA polymerase3–7. The trachoma agent and related psittacosis-lymphogranuloma agents are also inhibited in vitro and in embryonated eggs by this drug8. Further studies have shown that rifampicin is active against a number of bacteria in vivo, both after parenteral and oral administration1,9,10. It also inhibits malaria in mice11 and trachoma in monkeys12,13 and is of special value in the treatment of human tuberculosis14–16. The low toxicity of the rifamycins in mammals17 has been attributed to the observed relative insensitivity of mammalian RNA polymerase to the rifamycins in vitro3,18.

Synthesis and maturation of ribosomal RNA during the developmental cycle of trachoma agent, a prokaryotic obligate parasite of eukaryocytes

Trachoma agent, an obligate prokaryotic parasite of eukaryocytes, develops in the host-cell cytoplasm. During a developmental cycle of 48 hours the trachoma elementary body develops into a large inclusion body in which the progeny of elementary bodies is formed. The rate of trachoma RNA synthesis in the infected cell cytoplasm gradually increased during the initial 30 hours after infection but declined thereafter. Analysis of the RNA species synthesized at different stages of the trachoma developmental cycle demonstrated the synthesis of 23 s ribosomal RNA molecules as well as of 17.2 s and 16 s RNA species. Such RNA species were not found in uninfected cells. The synthesis of the trachoma-specific RNA species was inhibited by rifampicin. Analysis of the RNA species present in infectious trachoma elementary bodies demonstrated the presence of 23 s and 16 s mature ribosomal RNA molecules. The 17.2 s RNA molecules appear only during the development of the inclusion bodies. Trachoma agent also replicates in emetine-treated FL cells, in which the synthesis and the processing of the precursor to cellular ribosomal RNA is inhibited. The nature of trachoma agent 17.2 s RNA species was determined by chase experiments. It was found that under these conditions radioactivity in the 17.2 s rRNA species decreased while radioactivity of the 16 s mature rRNA species increased. A similar chase experiment in the presence of actinomycin D revealed a gradual decrease of the radioactivity in the 17.2 s precursor molecules, but only part of the radioactivity appeared in the 16 s rRNA species indicating a further degradation of the precursor molecules. Under these conditions the radioactivity in the trachoma-specific 23 s rRNA gradually increased. These studies also demonstrated that (a) the processing of the 17.2 s precursor to 16 s rRNA is a slow process; (b) the trachoma 23 s RNA species might be formed from a precursor of higher molecular weight; (c) treatment of the cells with chloramphenicol did not prevent the initial synthesis of the precursor molecules but inhibited the conversion of the 17.2 s precursor molecules to mature 16 s rRNA; and (d) puromycin affected the synthesis of the trachoma 17.2 s precursor RNA molecules and inhibited the formation of the mature 16 s rRNA.