Chlamydia trachomatis infections in infants.

In recent years considerable progress has been made in understanding chlamydial infections. The spectrum of pediatric Chlamydia trachomatis infection includes neonatal inclusion conjunctivitis, infantile pneumonia, occasional respiratory or genital tract infections in older children and sexually transmitted diseases in adolescents. The role of maternal chlamydial infection in prematurity and in perinatal death is currently an area of active study. We outline the current knowledge of the biologic characteristics of C. trachomatis, the epidemiologic features of chlamydial infection, and the clinical aspects, diagnosis and treatment of neonatal chlamydial infections.     

Chlamydia trachomatis infections in women with urogenital symptoms.

Chlamydia trachomatis was isolated from 30 to 100 women attending a family physician''s office with dysuria, frequency or vaginal discharge, compared with 2 of 30 asymptomatic women. Multiple infections were common: C. trachomatis coexisted with Gardnerella vaginalis, Candida albicans, Trichomonas vaginalis or a bacterial cause of urinary tract infection in 15 patients. C. trachomatis was isolated alone from 15 symptomatic women. The source of the positive culture was not always the site of symptoms. C. trachomatis was isolated from both the cervix and the urine of 9 patients, either simultaneously or sequentially. The probability of finding a chlamydial infection was 30% in young women with vaginal discharge alone, 33% in those with dysuria and frequency alone and 53% in those with abdominal or pelvic pain in addition to lower urogenital tract symptoms.     

Prevalence of Chlamydia trachomatis infections in Karachi, Pakistan.

An epidemiological study was carried out to determine the prevalence of Chlamydia infections in adult females by enzyme immunoassay and microscopic examination of Giemsa-stained smears. Endocervical swabs were collected from 126 females attending OB/GYN ward at Abbasi Shaheed Hospital, Karachi. 13.5% of 126 females tested were positive by enzyme immunoassay and only 5.6% were positive by the Giemsa-staining method. The infection rate among pregnant and nonpregnant women with urinogenital problems were 11.8% and 14.7%, respectively. The majority of females complained of excessive cervical discharge and pain in the lower abdomen. A high prevalence of infection in normal pregnant women (18.2%) indicates the asymptomatic nature of this infection.     

Epidemiology of sexually transmitted Chlamydia trachomatis infections in male patients

868 male urethritis patients were studied for the presence of chlamydiae in the 1981-1986 period. 36% of NGU, 31.3% of gonococcal urethritis and 58.8% of PGU urethritis patients presented C. trachomatis infections as detected by cell culture inoculation. Chlamydial infection was recorded more often in the 21-30 years age group (30.8%), in unmarried patients (70.6%), as well as in people with low educational degree (46.6% of cases), 42.3% of the C. trachomatis cases were already confronted with one or more urethritis episodes. 24.7% of patients have been subjected to a previous antichlamydial treatment.     

Chlamydia trachomatis infections in asymptomatic women. Results of a study employing different staining techniques

A total of 300 cervical smears randomly collected from asymptomatic women in a mass-screening program for the detection of cervical carcinoma was investigated for Chlamydia trachomatis infection by the use of Papanicolaou and immunofluorescence staining. Features of chlamydial infection detected in 18 cases by Papanicolaou-stained smears were confirmed in 11 cases with immunofluorescence; not a single case that was negative in the Papanicolaou-stained smears was positive by immunofluorescence. The presence of Chlamydia in the Papanicolaou-stained smears in ten cases, including two cases that were negative by immunofluorescence, was also proven by either immunoperoxidase staining or in situ hybridization. On the other hand, either immunoperoxidase or in situ hybridization gave false-negative results in two of the ten cases. Therefore, the combined use of different techniques demonstrated that false-negative results occurred with all techniques, except with Papanicolaou-stained smears, whose sensitivity is apparently the highest.     

Compensatory T cell responses in IRG-deficient mice prevent sustained Chlamydia trachomatis infections

The obligate intracellular pathogen Chlamydia trachomatis is the most common cause of bacterial sexually transmitted diseases in the United States. In women C. trachomatis can establish persistent genital infections that lead to pelvic inflammatory disease and sterility. In contrast to natural infections in humans, experimentally induced infections with C. trachomatis in mice are rapidly cleared. The cytokine interferon-γ (IFNγ) plays a critical role in the clearance of C. trachomatis infections in mice. Because IFNγ induces an antimicrobial defense system in mice but not in humans that is composed of a large family of Immunity Related GTPases (IRGs), we questioned whether mice deficient in IRG immunity would develop persistent infections with C. trachomatis as observed in human patients. We found that IRG-deficient Irgm1/m3((-/-)) mice transiently develop high bacterial burden post intrauterine infection, but subsequently clear the infection more efficiently than wildtype mice. We show that the delayed but highly effective clearance of intrauterine C. trachomatis infections in Irgm1/m3((-/-)) mice is dependent on an exacerbated CD4(+) T cell response. These findings indicate that the absence of the predominant murine innate effector mechanism restricting C. trachomatis growth inside epithelial cells results in a compensatory adaptive immune response, which is at least in part driven by CD4(+) T cells and prevents the establishment of a persistent infection in mice.     

Enzyme immunoassay in the diagnosis of Chlamydia trachomatis infections in diverse patient groups

An enzyme immunoassay (EIA) in parallel with cell culture was used to investigate the extent of infections due to Chlamydia trachomatis. EIA reactive confirmed in cell culture was taken as positive. C. trachomatis was found in 6 (26.0%) of 23 men with symptomatic non-gonococcal urethritis (NGU), ten (17.2%) of 58 symptom-free males and in three of 4 with postgonococcal urethritis. Among 106 asymptomatic pregnant women studied the incidence of C. trachomatis was 8.5% while a higher incidence (16.7%) was found in those with symptoms. C. trachomatis positivity in asymptomatic and symptomatic post-natal screening were 11.4% and 7.7%. Of 43 symptomatic non-pregnant females investigated, 7 (16.3%) were found to be positive for C. trachomatis. Of 3 women with PID, 2 (66.7%) harboured C. trachomatis in their cervix while in another 29 infertile women, C. trachomatis was positive in 3 (8.1%). Contraceptives appeared to have an effect on the chlamydial positivity. Comparative testing of EIA with the standard cell culture method in this study indicate EIA as a suitable alternative for the definitive diagnosis of chlamydial infection in high prevalence settings and with caution in low prevalence settings.     

Chlamydia trachomatis infection in rural Nova Scotia.

OBJECTIVE: To examine the demographic characteristics of patients who underwent testing for Chlamydia trachomatis and to determine the clinical and behavioural characteristics and the types of treatment for those who had positive test results. DESIGN: Case series. SETTING: Rural county in Nova Scotia. PATIENTS: All residents of the county for whom testing for C. trachomatis was ordered at the regional hospital from Sept. 1, 1990, to Mar. 31, 1991. MAIN OUTCOME MEASURES: Rates of testing and of positive test results by age and sex. Comparison of patient and physician characteristics in relation to testing rates. RESULTS: Of the 1116 patients tested 58 (5.2%) had positive test results. Females accounted for 82.8% of those with positive results whose sex could be determined. Among the females the mean age of those with a positive result was 22.3 years, as compared with 27.5 years for those with a negative result (p < 0.0001). Females 15 to 19 years of age were less likely to have a test performed than women 20 to 29 years and were more likely to have a positive test result than the women in the older groups. Almost 9% of the testing among the females was in those over 39 years of age, although no infection was seen in this age group. The number of tests ordered per general or family practitioner varied from 1 to 154; the physicians'' sex, practice location and length of time in practice did not predict the rates of positive test results. Treatment was most often in keeping with that recommended by national guidelines. Four (8.5%) of the 47 patients with positive results who were interviewed were not aware of their diagnosis, either because they had not returned for follow-up or had not being notified by the physician''s office. CONCLUSIONS: The frequency of testing for C. trachomatis infection may be less than is desirable among young patients, who, if tested, are more likely than older patients to have positive results. More understanding of the diagnostic approach taken by physicians is needed.     

Endocervical Chlamydia trachomatis infection in Canadian adolescents.

The highest prevalence rate of sexually transmitted chlamydial infection is among adolescent girls. To determine the rate among predominantly asymptomatic girls who were seen at a pediatric gynecology unit and to identify those at high risk we screened 541 such patients from Jan. 1 to Dec. 31, 1986, by means of direct fluorescent antibody testing; 422 (78.0%) were asymptomatic. The most common reason for presentation was a request for contraceptive advice (the reason for 59.2% of the patients). Of the 446 patients (82.4%) who were sexually active 66 (14.7%) had evidence of chlamydial infection; none of the 93 sexually inactive patients were infected. Neisseria gonorrhoeae was isolated from eight (1.5%) of the patients. The risk factors that correlated with chlamydial infection were abnormal vaginal discharge, abdominopelvic pain and an abnormal Papanicolaou test result. Because of the high morbidity rate associated with genital chlamydial infection and the high prevalence rate among adolescent girls, most of whom are asymptomatic, all sexually active teenagers should be screened.     

The glycyl-tRNA synthetase of Chlamydia trachomatis.

Aminoacyl-tRNA synthetases specifically charge tRNAs with their cognate amino acids. A prototype for the most complex aminoacyl-tRNA synthetases is the four-subunit glycyl-tRNA synthetase from Escherichia coli, encoded by two open reading frames. We examined the glycyl-tRNA synthetase gene from Chlamydia trachomatis, a genetically isolated bacterium, and identified only a single open reading frame for the chlamydial homolog (glyQS). This is the first report of a prokaryotic glycyl-tRNA synthetase encoded by a single gene.     

Cloning, expression, and primary structure of a Chlamydia trachomatis binding protein.

The gene encoding an 18,000-dalton eucaryotic cell-binding protein of Chlamydia trachomatis serovar L2 was cloned into Escherichia coli, and the nucleotide sequence of a 1,658-base-pair PstI restriction endonuclease fragment encoding this protein was determined. The recombinant chlamydial gene consists of a 486-base-pair open reading frame encoding a polypeptide of molecular weight 18,314. The resultant polypeptide, comprising 162 amino acids, possesses a highly charged carboxy-terminal end. The expression of this recombinant protein is under the control of a vector promoter. The recombinant 18,000-dalton protein possessed the same eucaryotic cell-binding characteristics as did the native chlamydial 18,000-dalton protein when electrophoresed and transferred to nitrocellulose. Polyclonal antibodies to the recombinant protein exhibited neutralizing activity.     

Chlamydia trachomatis in cell culture

Summary Trachoma organisms of serotype B were grown serially in irradiated cells (McCoy, BHK-21, Microbiological Associates, and BHK-21, Lister) and tested for infectivity in monolayers of five mammalian cell lines (BHK-21, CHO, HeLa S₃, McCoy and OWMK) and two diploid strains (ST/BTL and WI-38). All cell types had low susceptibility to chlamydial infection but the number of inclusions increased when the inoculum was centrifuged onto the monolayers, or when the cells were irradiated. Infection was higher in non-irradiated CHO than in irradiated CHO in three out of a total of six experiments. Inclusion number was increased 300 times in HeLa S₃ and up to three times in the other cell types after treatment with diethylaminoethyl-dextran (DEAE-D). Serial passage of Chlamydia trachomatis serotype B (strain Har-36) in CO₆₀ McCoy and CO₆₀ BHK-21 Lister resulted in partial adaptation of the strain to the host cell. The phenomenon of adaptation of serotype B to McCoy compensated for the lower susceptibility of this cell revealed when McCoy cells were inoculated with trachoma elementary bodies grown in BHK-21 Lister or in chick embryo yolk sac. Trachoma organisms of immunotypes A, B and C prepared in yolk sac produced more inclusion-forming units per ml in CO₆₀ BHK-21 Lister than in CO₆₀ McCoy. This research was supported by a grant from the National Eye Institute (EI-00812-08), and by the Arabian American Oil Company. The paper is dedicated to the memory of Francis B. Gordon, who pioneered research methods for the cultivation of trachoma and inclusion conjunctivitis (TRIC) agents in cell culture. Dr. Gordon patiently studied tables and photographs which accompany this text when he visited our laboratory on the day prior to his sailing to England on the ill-fated voyage in which he and Mrs. Gordon perished (October 1973).