Detection of Neisseria gonorrhoeae infection by ligase chain reaction testing of urine among adolescent women with and without Chlamydia trachomatis infection.

BACKGROUND AND OBJECTIVES: Culture, the conventional method for detection of Neisseria gonorrhoeae, requires invasive sampling and stringent specimen transport conditions. The recently developed ligase chain reaction test (LCR; Abbott Laboratories; North Chicago, IL) allows noninvasive sampling and stable transport conditions, but has not been evaluated with specimens from adolescent populations. GOAL OF THIS STUDY: To perform a comparative evaluation of a commercial LCR test and culture for the diagnosis of N. gonorrhoeae in adolescent women. STUDY DESIGN: Urine and endocervical swab specimens from 330 teenage women seen in two public health adolescent clinics were tested by LCR and culture. For resolution of discordant results, a polymerase chain reaction (PCR) test was developed that directly amplifies N. gonorrhoeae DNA from urine samples processed for LCR. RESULTS: Thirty-one of 330 (9.4%) cervical specimens were culture-positive for N. gonorrhoeae, and 30 of 330 (9.1%) urine specimens were positive by LCR. After resolution of 13 discordant results, the sensitivity, specificity, and positive and negative predictive values of LCR for urine were 88.2%, 100%, 100%, 98.7%, respectively, and for culture of endocervical specimens were 82.3%, 98.9%, 90.3% and 98%, respectively. CONCLUSIONS: Although more expensive than culture, LCR offers a sensitive means for the detection of N. gonorrhoeae in urine samples and may be useful for this purpose in settings where pelvic examinations are difficult to perform and simultaneous detection of N. gonorrhoeae and Chlamydia trachomatis is advantageous.

Immune control of Chlamydial growth in the human epithelial cell line RT4 involves multiple mechanisms that include nitric oxide induction, tryptophan catabolism and iron deprivation.

The antimicrobial activity of T cell-derived cytokines, especially interferon (IFN)-gamma, against intracellular pathogens, such as Chlamydia trachomatis, involves the induction of 3 major biochemical processes: tryptophan catabolism, nitric oxide (NO) induction and intracellular iron (Fe) deprivation. Since the epithelial cell is the natural target of chlamydial infection, the presence of these antimicrobial systems in the cell would suggest that they may be involved in T cell control of intracellular multiplication of Chlamydia. However, the controversy over whether these 3 antimicrobial processes are present in both mice and humans has precluded the assessment of the relative contribution of each of the 3 mechanisms to chlamydial inhibition in the same epithelial cell from either mice or humans. In the present study, we identified a Chlamydia-susceptible human epithelial cell line, RT4, that possesses the 3 antimicrobial systems, and we examined the role of nitric oxide (NO) induction, and deprivation of tryptophan or Fe in cytokine-induced inhibition of chlamydiae. It was found that the 3 antimicrobial systems contributed to cytokine-mediated inhibition of the intracellular growth of Chlamydia. NO induction accounted for approximately 20% of the growth inhibition; tryptophan catabolism contributed approximately 30%; iron deprivation was least effective; but the combination of the 3 systems accounted for greater than 60% of the inhibition observed. These results indicate that immune control of chlamydial growth in human epithelial cells may involve multiple mechanisms that include NO induction, tryptophan catabolism and Fe deprivation.

Route of infection that induces a high intensity of gamma interferon-secreting T cells in the genital tract produces optimal protection against Chlamydia trachomatis infection in mice.

The induction of local T helper type 1 (Th1)-mediated cellular immunity is crucial for resistance of mice to genital infection by the obligate intracellular bacterium Chlamydia trachomatis. We tested the hypothesis that the route of immunization that elicits relatively high numbers of chlamydia-specific, gamma interferon (IFN-gamma)-secreting T lymphocytes (ISTLs) in the genital tract would induce optimal protective immunity against reinfection. Female BALB/c mice were infected intravaginally (i.v.), intranasally (i.n.), orally (p.o.), or subcutaneously (s.c.) with C. trachomatis. At days 7, 14, 21, and 28 postinfection, T cells isolated from the genital tract tissues were restimulated with chlamydial antigen in vitro, and the amounts of IFN-gamma induced were measured by a sandwiched enzyme-linked immunosorbent assay method. At day 7 postinfection, i.n.- and i.v.-immunized mice had high levels of chlamydia-specific ISTLs in their genital tracts (203.58 +/- 68.1 and 225.5 +/- 12.1 pg/ml, respectively). However, there were no detectable ISTLs in the genital tracts of p.o.- or s.c.-infected mice. When preinfected mice were challenged i.v. 70 days later, animals preexposed by the i.n. route were highly resistant to reinfection, with greatly reduced chlamydial burden, and suffered an attenuated infection that resolved by day 6 postchallenge. Animals preexposed by the i.v. route were modestly protected, whereas p.o. and s.c. groups were indistinguishable in this regard from control mice. The resistance of i.n.-immunized mice (and to some extent the i.v.-exposed mice) to reinfection was associated with early appearance (within 24 h) of high levels of genital ISTLs compared with mice preinfected by other routes. Furthermore, although i.n. and i.v.-immunized mice had comparable levels of chlamydia-specific immunoglobulin A (IgA) antibodies in their vaginal washes, the levels of IgG2a were four- sixfold higher in i.n.-immunized mice than in any of the other groups. The results suggested that immunization routes that foster rapid induction of vigorous genital mucosal cell-mediated immune (CMI) effectors (e.g., IFN-gamma), the CMI-associated humoral effector, IgG2a, and to some extent secretory IgA produce protective immunity against chlamydial genital infection. Therefore, i.n. immunization is a potential delivery route of choice in the development of a vaccine against Chlamydia.

A pilot study of the prevalence of chlamydial infection in a national household survey.

BACKGROUND: The prevalence of Chlamydia trachomatis genital infection in the United States population is unknown. Using a new urine test for C. trachomatis, we conducted a pilot survey as part of the National Health and Nutrition Examination Survey III (NHANES III). GOAL: To determine whether the prevalence of chlamydial infection in a convenience sample of NHANES participants was high enough to justify testing for C. trachomatis in a national survey. STUDY DESIGN: NHANES III, conducted from 1988 to 1994, was based on a stratified multistage probability sample of the United States population. Non-Hispanic blacks and Mexican-Americans were oversampled. Using the ligase chain reaction assay for C. trachomatis, we tested urine from participants 12 to 39 years of age from 10 of the 89 sites of NHANES III. The prevalence of infection was calculated by racial or ethnic group. RESULTS: We tested 1,144 study participants, of whom 65% were female, 30% were non-Hispanic blacks, and 30% were Mexican-American. Prevalence was higher for non-Hispanic blacks (7%) than for Mexican-Americans (3%) and non-Hispanic whites (2%). Prevalence was higher for women than men in non-Hispanic blacks (7% vs. 6%), Mexican-Americans (5% vs. 2%), and non-Hispanic whites (2% vs. 1%). In 15- to 19-year-old women, prevalence was 13% in non-Hispanic blacks, 11% in Mexican-Americans, and 5% in non-Hispanic whites. CONCLUSION: The prevalence of C. trachomatis genital infection was high enough to suggest that a reliable national prevalence estimate could be obtained in a national probability sample survey.

Genetic variability of HIV type 1 in Honduras.

PIP: While Honduras is home to only 15% of Central America's population, it has 60% of the region's AIDS cases. There have been 4973 reported cases of full-blown AIDS in the country and the Health Ministry reports that more than 8000 Hondurans have been infected with HIV since the first Honduran case was diagnosed in 1985. 995 people with AIDS have since died. The authors conducted an investigation to determine which HIV-1 subtype is present in Honduras and the degree of genetic variation among HIV-1 strains by analyzing viral nucleotide sequences from the envelope region of HIV-1 isolates obtained from the two most affected regions of the country. They determined the predominant HIV-1 subtype among 27 HIV-1-infected patients attending sexually transmitted disease clinics in San Pedro Sula and Tegucigalpa by sequencing and analyzing the C2V3 regions of the envelope glycoprotein gp 120. Genomic DNA was isolated from patients' peripheral blood mononuclear cells. Phylogenetic analysis determined that all 27 Honduran sequences clustered with known subtype B sequences.^ieng