Prevalence of Chlamydia trachomatis and genital mycoplasmas in asymptomatic women.

To establish the prevalence of Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum in women attending a family planning and a prenatal clinic in Halifax, cervical swabs were obtained at the time of the first visit from 491 women who had no symptoms of genital infection. Among the women attending the family planning clinic M. hominis occurred in combination with C. trachomatis more frequently than expected (p less than 0.05). It occurred in the absence of U. urealyticum in only a few cases (13% of the occurrences in the family planning clinic and 6% of those in the prenatal clinic). C. trachomatis was significantly more prevalent in women under 25 years of age (p less than 0.04). However, mycoplasmas were as prevalent in women over 30 years as in those under 30. There were no significant differences in the infection rates of the organisms by trimester among pregnant women. More research is necessary for a proper understanding of the role of M. hominis and U. urealyticum in genitourinary infections and pregnancy outcomes.     

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.     

Presence of Chlamydia trachomatis in young women in Northern Sardinia

Chlamydia trachomatis infection is the most common sexually transmitted disease among women. The aim of this study was to determine by PCR the incidence of C. trachomatis among young women in Northern Sardinia since no studies are present in this area. The results obtained showed a moderate increase of chlamydial infection since 1997.     

Prevalence of Chlamydia trachomatis and oncogenic human papillomavirus types in cytologic atypia of the uterine cervix

A history of having substantial Chlamydia trachomatis exposure as detected by serum antibodies is a cofactor of human papillomavirus (HPV) mediated cervical carcinogenesis. In this study, we examined the concurrent C. trachomatis infections in cytologic atypia of the uterine cervix in order to evaluate the impact of C. trachomatis infection in patients with high risk for cervical intraepithelial neoplasia. Cervical scrapes form 707 patients were subjected to PCR amplification with primer sets for HPV and C. trachomatis. Based on negative beta-globin results, 10 specimens were not eligible for further analysis. Oncogenic HPV types were detected in 278 specimens (39.8%). C. trachomatis was found only in six specimens (0.9%). In conclusion, concurrent C. trachomatis infection was uncommon and hence it was an improbable risk factor in cytologic atypia.     

Prevalence of antibodies to Chlamydia trachomatis in healthy population groups in Manitoba.

The prevalence of antibodies to Chlamydia trachomatis was determined in 1877 serum samples from healthy population groups of Caucasians, native Indians and recent Vietnamese immigrants in Manitoba. Testing was done with a commercially available immunofluorescence kit containing C. trachomatis antigen. The presence of antibodies was age-related; a progressive increase in prevalence was observed in children aged 1 to 15 years, and the overall prevalence was higher in female Caucasian blood donors and female Vietnamese immigrants than in males in both groups. However, there was no sex-related difference in prevalence among the subjects undergoing premarital testing or among the native Indians. Antibodies were more prevalent (p less than 0.001) in pregnant than in nonpregnant women matched for race and age, and a relatively high prevalence (66.6%) was found in the cord serum of newborns. The overall prevalence rate of antibodies in all Manitobans was 48.8% (44.9% in men, 55.9% in women and 35.3% in children.     

Prevalence of hepatitis-B surface antigen among blood donors and human immunodeficiency virus-infected patients in Jos, Nigeria

Information is very scarce on the prevalence of hepatitis-B virus (HBV) infection among blood donors and patients with human immunodeficiency virus (HIV) infection in Nigeria. Hepatitis-B surface antigen (HBsAg) ELISA was used to determined the prevalence of HBsAg among 175 blood donors (aged 20-40 years) and 490 HIV-infected patients (aged 17-60 years) in Jos, Nigeria. Twenty-five (14.3%) of the blood donors and 127 (25.9%) of the HIV-infected individuals were HBsAg seropositive, indicating a higher HBV infection among HIV-infected persons than among healthy blood donors. A slightly higher HBsAg seroprevalence was recorded in the males (14.6%) than females (12.9%) of the blood donors. Among the HIV-infected patients, the males had considerably higher HBsAg seroprevalence than the females (31.8 vs 22.1%) with the highest prevalence of HBsAg occurring in the 51-60 years age group (44%), followed by those of 31-40 years (28.2%). Results confirmed the high endemicity of HBV infection in Jos, Nigeria and the significantly greater prevalence of HBV infection among HIV-infected patients than among blood donors.     

Antibodies to human immunodeficiency virus in human sera induce cell-mediated lysis of human immunodeficiency virus-infected cells

The capacity of human immunodeficiency virus (HIV) antibody-positive sera from homosexually active men without acquired immune deficiency syndrome to lyse the HIV-infected T cell lines MOLT-4f and CCRF-CEM (CEM) in cooperation with lymphocytes from normal donors was investigated. Twenty-seven HIV antibody-positive sera, most of which enhanced the killing of HIV-infected MOLT-4f and CEM target cells by normal mononuclear cells were studied in detail. HIV antibody-positive sera resulted in lysis at dilutions as high as 1/10,000. HIV antibody-negative sera did not augment lysis of infected target cells. In addition, lysis of uninfected targets was not enhanced in the presence of HIV antibody-positive sera. Because fractionation of the HIV antibody-positive sera on a protein A affinity column resulted in recovery of the activity from the IgG fraction, the extra cytotoxic activity mediated by nonimmune cells in the presence of immune sera appears to be antibody-dependent. Furthermore, the cytotoxic effector cells were in the nonrosetting fraction of lymphocytes and expressed Leu-11 (cluster designation (CD)15) antigens, which is characteristic of cells participating in antibody-dependent cellular cytotoxicity reactions. The antibody specificity of the sera, determined by radioimmunoprecipitation, provides evidence that antibody-dependent cellular cytotoxicity can occur even when there are no detectable antibodies directed against gag proteins. Sera which lacked detectable antibodies to the envelope protein gp120 by radioimmunoprecipitation did not mediate antibody-dependent cellular cytotoxicity.     

Interaction of Chlamydia trachomatis with human genital epithelium in culture

Primary cultures of human endometrial and ectocervical epithelial cells were examined as a new model system to study genital infection by Chlamydia trachomatis. Initial studies demonstrated that these cells were indeed susceptible to chlamydial infection. Inocula, adjusted to produce inclusions in 50 to 80% of equivalent numbers of standard McCoy cells, resulted in infection rates of approximately 15 to 30% for the columnar cells of the endometrium and 5 to 10% for the squamous cells of the ectocervix. Exposure of cultures to DEAE-dextran and centrifugation-assisted inoculation, manipulations reported to enhance infection of HeLa and McCoy cells, did not alter the number of inclusion-positive genital cells. Addition of cycloheximide to the post-inoculation culture medium slightly increased numbers of inclusion-bearing cells while growth of genital cells in hormone-supplemented medium resulted in a variable effect on inclusion development and a significant reduction in the association of radiolabelled organisms with these cells. The basis for the different levels of infection in McCoy versus genital cell cultures was revealed by immunofluorescence analysis of chlamydial association with host cells immediately after inoculation. Chlamydiae failed to adhere to many cells in the genital cell cultures while adherence to McCoy cells was uniform. In addition, the association of radiolabelled C. trachomatis was significantly lower with genital cells than with McCoy cells. Finally, culture conditions were defined which markedly inhibited inclusion development without an immediate loss of chlamydial growth potential. This investigation indicates that primary genital cell cultures are susceptible to chlamydial infection and will be valuable for studies on the nature of C. trachomatis interactions with natural human target cells.     

Chlamydia trachomatis infection of human fallopian tube organ cultures

The pathogenic events that precede Chlamydia trachomatis salpingitis in the human fallopian tube have not been fully described. We used a model of human fallopian tubes in organ culture (HFTOC) infected with strain E/UW-5/CX of C. trachomatis to study these events. The model supported sustained C. trachomatis infection as demonstrated by recovery of viable C. trachomatis from medium and tissue over 5-7 d. However, the level of infectivity was low. Maximal infection occurred at 72 h after initial inoculation. In contrast to gonococcal infection of the HFTOC, C. trachomatis did not damage overall ciliary function of HFTOC. However, a local direct cytotoxic effect characterized by loss of microvilli and disruption of cell junctions was noted when multiple chlamydial elementary bodies attached to mucosal cells. Beginning at 24 h, and continuing throughout the course of C. trachomatis infection of HFTOC, ruptured epithelial cells releasing elementary bodies were noted. Chlamydial inclusions were seen in the mucosa by 72 h in approximately 6% of both ciliated and nonciliated epithelial cells. Mucosal inclusions contained all forms of the C. trachomatis developmental cycle. These data suggest that factors present in the human fallopian tube may limit susceptibility to chlamydial infection but support the use of the HFTOC model in the study of the pathogenesis of C. trachomatis salpingitis.     

Infertility in mice infected genitally with a human strain of Chlamydia trachomatis

Progesterone-treated C3H and TO mice were inoculated genitally with a human C. trachomatis strain, serovar E, designated N.I. 1 or with 2SP control medium. Of the C3H mice serving as controls 93% had litters by the end of a 6-month period compared to 31% of mice infected with chlamydiae. This infertility could not be explained by tubal occlusion, since the oviducts appeared normal at autopsy. Some of the mice were induced to superovulate. Eggs were never recovered from the oviducts on the inoculated sides of infertile mice although they were sometimes found in the lumen of the uninoculated oviducts. In contrast, eggs were recovered routinely from both oviducts of control mice. In addition, eggs and/or their accompanying cumulus cells could be seen in the periovarial space of mice inoculated with chlamydiae, indicating a failure of the transportation of eggs to the oviduct. This could explain the high incidence of ectopic pregnancies in women after chlamydial infection. No adverse effect on fertility was seen in TO mice inoculated genitally with strain N.I.1. Of the mice given 2SP medium, 73% had litters, but 87% of the mice inoculated with chlamydiae were also fertile. There was, however, a significantly greater variation in the birth weights of mice born to infected TO mothers than those born to control mice. This difference in the susceptibility of mouse strains suggests that a genetic predisposition should also be considered for man.     

Forward Genetic Approaches in Chlamydia trachomatis

Chlamydia trachomatis, the etiological agent of sexually transmitted diseases and ocular infections, remains poorly characterized due to its intractability to experimental transformation with recombinant DNA. We developed an approach to perform genetic analysis in C. trachomatis despite the lack of molecular genetic tools. Our method involves: i.) chemical mutagenesis to rapidly generate comprehensive libraries of genetically-defined mutants with distinct phenotypes; ii.) whole-genome sequencing (WGS) to map the underlying genetic lesions and to find associations between mutated gene(s) and a common phenotype; iii.) generation of recombinant strains through co-infection of mammalian cells with mutant and wild type bacteria. Accordingly, we were able to establish causal relationships between genotypes and phenotypes. The coupling of chemically-induced gene variation and WGS to establish correlative genotype–phenotype associations should be broadly applicable to the large list of medically and environmentally important microorganisms currently intractable to genetic analysis.     

Complement C3 opsonization of Chlamydia trachomatis facilitates uptake in human monocytes

Chlamydia trachomatis is an obligate intracellular bacterium that causes severe infections, which can lead to infertility and ectopic pregnancy. Although both innate and adaptive immune responses are elicited during chlamydial infection the bacterium succeeds to evade host defense mechanisms establishing chronic infections. Thus, studying the host–pathogen interaction during chlamydial infection is of importance to understand how C. trachomatis can cause chronic infections. Both the complement system and monocytes play essential roles in anti-bacterial defense, and, therefore, we investigated the interaction between the complement system and the human pathogens C. trachomatis D and L2.Complement competent serum facilitated rapid uptake of both chlamydial serovars into monocytes. Using immunoelectron microscopy, we showed that products of complement C3 were loosely deposited on the bacterial surface in complement competent serum and further characterization demonstrated that the deposited C3 product was the opsonin iC3b. Using C3-depleted serum we confirmed that complement C3 facilitates rapid uptake of chlamydiae into monocytes in complement competent serum. Complement facilitated uptake did not influence intracellular survival of C. trachomatis or C. trachomatis-induced cytokine secretion. Hence, C. trachomatis D and L2 activate the complement system leading to chlamydial opsonization by iC3b and subsequent phagocytosis, activation and bacterial elimination by human monocytes.     

Higher Chlamydia trachomatis Prevalence in Ethnic Minorities Does Not Always Reflect Higher Sexual Risk Behaviour

Background

In affluent countries, the prevalence of Chlamydia trachomatis (CT) is often higher in certain ethnic minorities than in the majority population. In the Netherlands, we examined why CT prevalence is higher in Surinamese/Antilleans, the largest minority in the country.

Methods

Heterosexuals were recruited for a cross-sectional survey from May through August 2010 at the sexually transmitted infections (STI) clinic in Amsterdam. Participants completed a questionnaire and were tested for STI. A causal directed acyclic graph was assumed to investigate whether the association between ethnicity and CT could be explained by differences in sexual risk behaviour and socio-economic status.

Results

Subjects included 1044 with Dutch background and 335 with Surinamese/Antillean background. Median age for the combined population was 25 (IQR 22-30) years, and 55.4% was female. Sexual risk behaviour did not differ significantly between the two groups. CT was diagnosed in 17.9% of Surinamese/Antilleans and in 11.4% of Dutch. Surinamese/Antilleans were significantly more likely to have CT (OR 1.70; 95% CI 1.21-2.38). The association between ethnicity and CT remained statistically significant after adjusting for sexual risk behaviour, age, sex, and ethnic mixing (aOR 1.48; 95% CI 1.00-2.18), but not after adjusting for education and neighbourhood, markers of socio-economic status (aOR 1.08; 95% CI 0.71-1.64).

Conclusion

The difference in CT prevalence between the minority and majority groups was not explained by differences in sexual risk behaviour. The higher CT prevalence found among Surinamese/Antilleans appeared to reflect their lower educational level and neighbourhood, two markers of lower socio-economic status. We hypothesise that the effect results from lower health-seeking behaviour.     

Developmental-stage-specific plasmid supercoiling in Chlamydia trachomatis

Chlamydia trachomatis elementary body (EB) and reticulate body (RB) developmental stages have polymorphic plasmid DNA. Several plasmid forms separated by gel electrophoresis were identified as topoisomers by treatment with topoisomerase I. Among these topoisomers was one form unique to EBs and one form unique to RBs. The unique EB plasmid topoisomer was characterized as highly supercoiled, on the basis of band migrations by gel electrophoresis and its appearance by electron microscopy. The unusual physical state of this topoisomer was probably mediated, in part, by DNA-specific structural proteins. The unique RB plasmid topoisomer was a supercoiled form of lower superhelical density than the other identified topoisomers. Developmental-stage-specific differences in super-helical density of plasmid DNA suggest cause-and-effect relationships between DNA topology and metabolic activity in RBs and metabolic quiescence in EBs.     

Prevalence of human immunodeficiency virus infection in alcoholics

To verify the prevalence of infection by human immunodeficiency virus (HIV) in alcoholics we studied 131 alcoholic patients (119 males and 12 females) with a mean age of 44.3 +/- 10.8 years. Serum samples were collected from this group and analysed, by ELISA, for antibodies against HIV as well as for serological markers for hepatitis B virus (HBV) and hepatitis C virus (HCV). As we have previously described, we found a high prevalence of HBV (26.4%) and HCV (4.2%) markers as compared to the prevalence of these markers in samples of normal blood donors from Uberlandia's Hemocentro Regional, which are 4% and 0.4%, respectively. Of the 131 patients, four (3%) had antibodies against HIV, three (75%) of which were injecting drug users (IDU). In the HIV-negative group, only one patient was an IDU. The prevalence of HIV in our population, according to data from the city's Health Secretary, varies from 3.1% to 6.2%. We conclude that, at least for the moment, alcoholism per se, did not constitute an important risk factor for HIV infection. However, acquired immunodeficiency syndrome is a rather recent disease as compared to hepatitis B and C and, as the transmission routes are similar for HIV and hepatitis viruses, an increase in the incidence of HIV infection in alcoholics may be just a question of time.     

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.