Diagnosis of Trichomonas vaginalis infection by PCR using vaginal swab samples

Trichomonas vaginalis infection is the most prevalent nonviral sexually transmitted disease (STD) in the world. A PCR test using vaginal swab samples for the detection of T. vaginalis was developed to add T. vaginalis infection to the growing list of STDs that can be detected by DNA amplification techniques. A primer set, BTUB 9/2, was designed to target a well-conserved region in the beta-tubulin genes of T. vaginalis. All strains (15 of 15) of T. vaginalis tested were successfully detected by PCR giving a single predicted product of 112 bp in gel electrophoresis. No such targeted product was amplified with DNA from Trichomonas tenax, Trichomonas gallinae, Chlamydia trachomatis, Neisseria gonorrhoeae, Giardia lamblia, Chilomastix sulcatus, Dientamoeba fragilis, and Entamoeba histolytica. An optimal analytical sensitivity of one T. vaginalis organism per PCR was achieved. Culture, performed with the Inpouch TV culture system, was examined daily with a light microscope to identify T. vaginalis. Twenty-three of 350 (6.6%) vaginal swab samples from women attending an army medical clinic were culture positive for T. vaginalis. Of these culture positive specimens, PCR detected 22 of 23 (96%) with primer set BTUB 9/2, and wet preparation detected only 12 of 23 (52%). Seventeen specimens were BTUB 9/2-PCR positive and culture negative. Ten of these discordant specimens were determined to be as true positive by PCR using primer sets TVA 5-1/6 and/or AP65 A/B, which target different regions in the T. vaginalis genome, and seven were determined to be false positive. The sensitivity of BTUB 9/2-PCR was 97% and the specificity was 98%. The sensitivities of culture and wet preparation were 70 and 36%, respectively. The diagnosis of T. vaginalis infection by PCR is a sensitive and specific method that could be incorporated into a joint strategy for the screening of multiple STDs by using molecular amplification methods.

Chlamydia trachomatis infections in female military recruits

BACKGROUND

Asymptomatic genital Chlamydia trachomatis infections in women can lead to pelvic inflammatory disease, infertility, and ectopic pregnancy. To design a chlamydia-control program, we conducted a large survey of women in the U.S. military.

METHODS

From January 1996 through December 1997, urine samples from 13,204 new female U.S. Army recruits from 50 states were screened by ligase chain reaction for C. trachomatis infection. Information on potential risk factors was obtained by questionnaire. With multivariate analysis, we identified criteria for a screening program.

RESULTS

The overall prevalence of chlamydial infection was 9.2 percent, with a peak of 12.2 percent among the 17-year-old recruits. The prevalence was 15 percent or more among the recruits from five southern states. The following risk factors were independently associated with chlamydial infection: having ever had vaginal sex (odds ratio for infection, 5.9), being 25 years of age or less (odds ratio, 3.0), being black (odds ratio, 3.4), having had more than one sex partner in the previous 90 days (odds ratio, 1.4), having had a new partner in the previous 90 days (odds ratio, 1.3), having had a partner in the previous 90 days who did not always use condoms (odds ratio, 1.4), and having ever had a sexually transmitted disease (odds ratio, 1.2). A screening program for subjects 25 years of age or less (87.9 percent of our sample) would have identified 95.3 percent of the infected women.

CONCLUSIONS

Among female military recruits, the prevalence of chlamydial infection is high. A control program that screens female recruits who are 25 years old or younger with urine DNA-amplification assays has the potential to reduce infection, transmission, and the sequelae of chlamydial infection.

Screening for gonorrhea and chlamydia by DNA amplification in adolescents attending middle school health centers. Opportunity for early intervention

GOAL

To determine prevalence and incidence of Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) infection and assess risk factors predictive for such infections in a middle school-based clinic sample.

STUDY DESIGN

170 female students and 43 male students making 256 and 47 visits, respectively, > or = 30 days apart, in urban middle school clinics for primary care screening, reproductive health, or illness/injury were routinely asked to provide urine specimens for GC and CT ligase chain reaction testing if sexually active in the preceding 3-month period. Information regarding prior sexually transmitted diseases, reason for visit, and sexual risk behaviors was obtained.

RESULTS

GC: 11.4% of female student and 2.1% of male student tests were positive. Incidence was 34.0 cases/1,000 person months (95% Confidence interval [CI]: 19.5-67.5). Median time to first positive and repeat positive test was 4.6 and 2.6 months, respectively. For CT: 16.4% of female student and 2.1% of male student tests were positive. Incidence was 57.5 cases/1,000 person months (95% CI: 35.2-93.8). Median time to first positive and repeat positive CT test was 6.0 and 4.8 months, respectively. Assessed risk factors failed to specify a candidate screening population.

CONCLUSION

These data suggest that all sexually active adolescent girls in this high risk setting should be offered testing for GC and CT at least twice per year, regardless of age or other sexual risk behaviors and that STD control efforts in high risk middle schools should be encouraged.

Detection of Mycoplasma pneumoniae in the airways of adults with chronic asthma

Infection with Mycoplasma pneumoniae has been shown to exacerbate asthma in humans. However, the role of M. pneumoniae in the pathogenesis of chronic asthma has not been defined. Eighteen asthmatics with chronic, stable asthma and 11 nonasthmatic control subjects underwent evaluation of the upper and lower airways and serologic analysis to determine the presence of M. pneumoniae, Chlamydia pneumoniae, and seven respiratory viruses through culture, enzyme-linked immunoassay (EIA) and polymerase chain reaction (PCR). M. pneumoniae was detected by PCR in 10 of 18 asthmatics and one of 11 control subjects (p = 0.02). In nine of the 10 patients, the organism was detected in bronchoalveolar lavage or bronchial biopsies. Seven of 18 asthmatics and one of 11 control subjects were also positive for M. fermentans and M. genitalium by PCR. All patients' cultures, EIAs, and serology were negative for M. pneumoniae. All PCR and cultures were negative for C. pneumoniae, and all EIAs for respiratory viruses were negative in all subjects. Nine asthmatics and one control subject exhibited positive serology for C. pneumoniae (p = 0.05). M. pneumoniae was present in the lower airways of chronic, stable asthmatics with greater frequency than control subjects, and may play a role in the pathogenesis of chronic asthma.

Incident Chlamydia trachomatis infections among inner-city adolescent females

CONTEXT

Adolescents are at highest risk for infection with Chlamydia trachomatis, an important preventable cause of pelvic inflammatory disease and subsequent tubal factor infertility in US women. Current guidelines for delivery of adolescent primary care services recommend yearly chlamydia screening for those adolescent females considered to be at risk.

OBJECTIVES

To describe the epidemiology of prevalent and incident chlamydia infection among adolescent females to assess the appropriate interval for chlamydia screening and to define risk factors that would identify adolescent females to target for screening.

DESIGN

Prospective longitudinal study.

PATIENTS

A consecutive sample of 3202 sexually active females 12 through 19 years old making 5360 patient visits over a 33-month period, January 1994 through September 1996.

SETTING

Baltimore, Md, family planning, sexually transmitted disease, and school-based clinics.

INTERVENTION

Testing for C trachomatis by polymerase chain reaction.

MAIN OUTCOME MEASURES

Prevalence and incidence of C trachomatis infections; predictors of positive test result for C trachomatis.

RESULTS

Chlamydia infection was found in 771 first visits (24.1%) and 299 repeat visits (13.9%); 933 adolescent females (29.1%) had at least 1 positive test result. Females who were 14 years old had the highest age-specific chlamydia prevalence rate (63 [27.5%] of 229 cases; P=.01). The chlamydia incidence rate was 28.0 cases per 1000 person-months (95% confidence interval, 24.9-31.5 cases). The median time was 7.2 months to a first positive chlamydia test result and 6.3 months to a repeat positive test result among those with repeat visits. Independent predictors of chlamydia infection--reason for clinic visit, clinic type, prior sexually transmitted diseases, multiple or new partners, or inconsistent condom use-failed to identify a subset of adolescent females with the majority of infections.

CONCLUSIONS

A high prevalence and incidence of C trachomatis infection were found among adolescent females. We, therefore, recommend screening all sexually active adolescent females for chlamydia infection every 6 months, regardless of symptoms, prior infections, condom use, or multiple partner risks.

Use of lambda phage DNA as a hybrid internal control in a PCR-enzyme immunoassay to detect Chlamydia pneumoniae

An inherent problem in the diagnostic PCR assay is the presence of ill-defined inhibitors of amplification which may cause false-negative results. Addition of an amplifiable fragment of foreign DNA in the PCR to serve as a hybrid internal control (HIC) would allow for a simple way to identify specimens containing inhibitors. Two oligonucleotide hybrid primers were synthesized to contain nucleic acid sequences of the Chlamydia pneumoniae 16S rRNA primers in a position flanking two primers that target the sequences of a 650-bp lambda phage DNA segment. By using the hybrid primers, hybrid DNA comprising a large sequence of lambda phage DNA flanked by short pieces of chlamydia DNA was subsequently generated by PCR, cloned into a plasmid vector, and purified. Plasmids containing the hybrid DNA were diluted and used as a HIC by adding them to each C. pneumoniae PCR test. Consequently, C. pneumoniae primers were able to amplify both chlamydia DNA and the HIC DNA. The production of a 689-bp HIC DNA band on an acrylamide gel indicated that the specimen contained no inhibitors and that internal conditions were compatible with PCR. Subsequently, a biotinylated RNA probe for the HIC was transcribed from a nested sequence of the HIC and was used for its hybridization. Detection of the HIC DNA-RNA hybrid was achieved by enzyme immunoassay (EIA). This PCR-EIA system with a HIC was initially tested with 12 previously PCR-positive and 14 previously PCR-negative specimens. Of the 12 PCR-positive specimens, 11 were reconfirmed as positive; 1 had a negative HIC value, indicating inhibition. Of the 14 previously PCR-negative specimens, 13 were confirmed as true negative; 1 had a negative HIC value, indicating inhibition. The assay was then used with 237 nasopharyngeal specimens from patients with pneumonia. Twenty-one of 237 (8.9%) were positive for C. pneumoniae, and 42 (17.7%) were found to inhibit the PCR. Specimens showing inhibitory activity were diluted 1:10 and were retested. Ten specimens were still inhibitory to the PCR and required further DNA purification. No additional positive samples were detected and 3 nasopharyngeal specimens remained inhibitory to PCR. Coamplification of a HIC DNA can help confirm true-negative PCR results by ruling out the presence of inhibitors of DNA amplification.

Implications for macrolide treatment in community-acquired pneumonia. Hopkins CAP Team

STUDY OBJECTIVES

To identify associated clinical parameters, concurrent respiratory tract infections, and the association between macrolide-based therapy and mortality in patients with community-acquired pneumonia ascribed to atypical.

DESIGN

Secondary analysis of prospective, cross-sectional study.

SETTING

Tertiary care hospital.

PATIENTS

Three hundred eighty-five consecutive patients who were admitted to the Johns Hopkins Hospital from November 11, 1990, through November 10, 1991, and treated for community-acquired pneumonia.

RESULTS

An atypical pathogen was identified in 29 of 385 adults (7.5%). A second pathogen was detected in 16 of 29 patients (55.2%) in whom an atypical pathogen was detected, compared with 13 of 137 patients (9.5%) in whom conventional bacterial pathogens were detected (odds ratio, 10.22; 95% confidence interval, 3.7 to 28.8; p<0.0001). During hospitalization, only four patients (13.8%) with detection of an atypical pathogen received at least 7 days of either a macrolide or tetracycline. No patient identified to have an atypical pathogen died. For patients who either provided paired sera or who died, 24 of 197 (12.2%) had atypical pathogens detected.

CONCLUSIONS

Despite vigorous study methods, atypical pathogens were uncommon in our hospitalized population. A second concurrent respiratory pathogen was identified for most patients with atypical pneumonia. Although macrolide use was rare in this patient population, mortality was zero for patients in whom an atypical pathogen was detected, affirming that macrolide-based therapy need not be routine in the therapeutic management of community-acquired pneumonia.

Use of ligase chain reaction with urine versus cervical culture for detection of Chlamydia trachomatis in an asymptomatic military population of pregnant and nonpregnant females attending Papanicolaou smear clinics

Ligase chain reaction (LCR) (Abbott Laboratories, Abbott Park, Ill.) with first-catch urine specimens was used to detect Chlamydia trachomatis infections in 465 asymptomatic military women attending clinics for routine Papanicolaou smear tests. Results were compared to results of cervical culture to determine the sensitivity of the urine LCR and the possible presence of inhibitors of amplification in pregnant and nonpregnant women. Discrepant results for LCR and culture were resolved by direct fluorescent antibody staining of culture sediments, two different PCR assays, and LCR for the outer membrane protein 1 gene. The prevalence of Chlamydia in specimens by urine LCR was 7.3% compared to 5% by culture. For 434 women with matching specimens, there were 11 more specimens positive by LCR than were positive by culture, of which all but one were determined to be true positives. There were four culture-positive, LCR-negative specimens, all from nonpregnant women. The sensitivity, specificity, and positive and negative predictive values of urine LCR after discrepant results were resolved were 88.6, 99.7, 96.9, and 99.0%, respectively. The sensitivity of culture was 71.4%. From the 148 pregnant women (prevalence by LCR, 6.8%), there were no patients who were cervical culture positive and urine LCR negative to indicate the presence in pregnant women of inhibitors of LCR. Additionally, a subset of 55 of the LCR-negative frozen urine specimens from pregnant women that had been previously processed in LCR buffer were inoculated with 5 cell culture inclusion forming units of C. trachomatis each and retested by LCR; all tested positive, indicating the absence of inhibitors of LCR in urine from these pregnant women. The use of LCR testing of urine specimens from asymptomatic women, whether pregnant or not, offers a sensitive and easy method to detect C. trachomatis infection in women.

Prevention of adenoviral acute respiratory disease in Army recruits: cost-effectiveness of a military vaccination policy

INTRODUCTION

Since 1971 widespread vaccination has limited the number of adenoviral acute respiratory disease (ARD) outbreaks in Army recruits. Increased vaccine costs have recently threatened the continuation of the vaccination program.

METHODS

We conducted a cost-effectiveness analysis to assess the consequences of changing the year-round Army adenovirus vaccination program to (1) seasonally targeted vaccine administration (only during the high-risk period) or (2) complete discontinuation of the program from the perspective of total cost to the Army. Costs included vaccination costs and direct and indirect medical and military training costs. Health outcomes were estimated as the number of hospitalizations for ARD prevented. In the reference case, the incidence rate among unvaccinated and vaccinated individuals was 4.06 and 1.5 per 100 person weeks, respectively. Results are expressed for a cohort of 76,171 recruits.

RESULTS

In the absence of adenoviral vaccination, a projected 12,370 cases of ARD hospitalization would occur, costing $26.4 million annually. A seasonally targeted program would prevent 7,800 cases of ARD and save $16.1 million over no vaccination. Year-round immunization would not prevent any additional cases but would save $15.5 million over no vaccination. Year-round vaccination would become the cost-effective strategy if ARD incidence during the low-risk months were to increase.

CONCLUSION

Vaccination of Army recruits by any schedule was cost-saving due to the high level of prevented disease and averted hospitalizations. Even though a seasonally targeted program provided the greatest cost-savings, year-round vaccination must remain an option due to the potential for adenoviral ARD outbreaks in the low-risk period.

Screening for Chlamydia trachomatis in asymptomatic women attending family planning clinics. A cost-effectiveness analysis of three strategies

BACKGROUND

Screening women for Chlamydia trachomatis in family planning clinics is associated with a reduced incidence of chlamydial sequelae. However, the question of whom to screen to maintain efficient use of resources remains controversial.

OBJECTIVE

To assess the cost-effectiveness of chlamydial screening done according to three sets of criteria in asymptomatic women attending family planning clinics.

DESIGN

Cost-effectiveness analysis done by using a decision model with the perspective of a health care system. Model estimates were based on analysis of cohort data, clinic costs, laboratory costs, and published data.

SETTING

Two family planning clinics in Baltimore, Maryland.

PATIENTS

7699 asymptomatic women who presented between April 1994 and August 1996.

INTERVENTION

Three screening strategies--screening according to the criteria of the Centers for Disease Control and Prevention (CDC), screening all women younger than 30 years of age, and universal screening--were retrospectively applied and compared. All women were tested with polymerase chain reaction.

MEASUREMENTS

Medical outcomes included sequelae prevented in women, men, and infants. Total costs included screening program costs and future medical costs of all sequelae. The incremental cost-effectiveness ratios of each strategy were calculated.

RESULTS

Without screening, 152 cases of pelvic inflammatory disease would occur at a cost of $676,000. Screening done by using the CDC criteria would prevent 64 cases of pelvic inflammatory disease at a cost savings of $231,000. Screening all women younger than 30 years of age would prevent an additional 21 cases of pelvic inflammatory disease and save $74,000. Universal screening would prevent an additional 6 cases of pelvic inflammatory disease but would cost $19,000 more than age-based screening, or approximately $3000 more per case of pelvic inflammatory disease prevented. If the prevalence of C. trachomatis is more than 10.2% or if less than 88.5% of infections occur in women younger than 30 years of age, universal screening provides the greatest cost savings.

CONCLUSIONS

These results suggest that age-based screening provides the greatest cost savings of the three strategies examined. However, universal screening is desirable in some situations. In general, screening done by using any criteria and a highly sensitive diagnostic assay should be part of any chlamydial prevention and control program or health plan.

Molecular amplification assays to detect chlamydial infections in urine specimens from high school female students and to monitor the persistence of chlamydial DNA after therapy

Polymerase chain reaction (PCR) and ligase chain reaction (LCR) were compared for the diagnosis of Chlamydia trachomatis infections by testing urine specimens from 408 high school female students. After therapy, sequential urine specimens were tested to determine persistence of chlamydial DNA in urine. Baseline PCR of cervical specimens was positive in 53 (13.0%) students, and PCR and LCR of urine specimens were positive in 63 (15.4%) and 60 (14.7%), respectively. After discrepant analysis, 64 (15.7%) patients could be confirmed as truly infected. Follow-up urine specimens from 33 infected patients demonstrated that at 1-3 days after therapy, PCR and LCR were positive for 40% and 73.3%, respectively. Only at 15 days after therapy did all specimens test negative. Urine tests for Chlamydia organisms should not be used as a test of cure within 3 weeks after treatment. Use of urine assays for screening sexually active adolescents has the potential to significantly improve control of chlamydial infections.

Screening women for chlamydia trachomatis in family planning clinics: the cost-effectiveness of DNA amplification assays

BACKGROUND

Highly sensitive and specific DNA amplification assays are available for use on cervical and urine specimens. These new tests have the potential to identify more chlamydial infections than the commonly used enzyme immunoassay and DNA probe tests, yet they are more expensive. This study sought to assess the cost effectiveness of cell culture, enzyme immunoassay (EIA), DNA probe (Pace 2), polymerase chain reaction (PCR) of cervical and urine specimens, and ligase chain reaction (LCR) of cervical and urine specimens as screening tools for Chlamydia trachomatis in asymptomatic women younger than 30 years of age attending family planning clinics.

STUDY DESIGN

Program costs; medical cost savings of prevented sequelae in women, male sex partners, and infant; and number of prevented cases of pelvic inflammatory disease (PID), neonatal infections, and male sex partner urethritis and epididymitis were modeled in a decision analysis conducted from a health care system perspective. Results are expressed for a cohort of 18,000 women.

RESULTS

If no screening for C. trachomatis were conducted in Maryland, 497 cases of PID would develop, costing $2.2 million in future medical costs. Use of EIA to detect chlamydial infection would prevent 240 cases of PID and save $887,000 over no screening. Alternatively, use of DNA amplification assays on urine specimens would prevent up to an additional 66 cases and save $287,100 over EIA. Use of LCR on cervical specimens would prevent at least 13 additional cases of PID over the urine-based assays, but would cost $3,005 for each additional case prevented. In women receiving routine pelvic examinations, LCR of cervical specimens would prevent the most disease and provide the highest cost savings. In women not receiving routine pelvic examinations, use of LCR on cervical specimens would prevent the most disease but would cost approximately $28,000 per additional case of PID prevented over DNA amplification of urine.

CONCLUSIONS

Compared with EIA screening, the strategy with the lowest program costs, a screening strategy that combines use of DNA amplification on cervical specimens in women receiving pelvic examinations, and DNA amplification of urine in women with no medical indications necessitating a pelvic examination, prevents the most cases of PID and provides the highest cost savings. With enhanced sensitivity over the other diagnostic assays and with the use of noninvasive specimen collection, DNA amplification assays should be implemented as cost-effective components of a screening program for C. trachomatis.

Pooling urine samples for ligase chain reaction screening for genital Chlamydia trachomatis infection in asymptomatic women

The accuracy of pooling urine samples for the detection of genital Chlamydia trachomatis infection by ligase chain reaction (LCR) was examined. A model was also developed to determine the number of samples to be pooled for optimal cost savings at various population prevalences. Estimated costs included technician time, laboratory consumables, and assay costs of testing pooled samples and retesting individual specimens from presumptive positive pools. Estimation of population prevalence based on the pooled LCR results was also applied. After individual urine specimens were processed, 568 specimens were pooled by 4 into 142 pools and another 520 specimens were pooled by 10 into 52 pools. For comparison, all 1,088 urine specimens were tested individually. The sample-to-cut-off ratio was lowered from 1.0 to 0.2 for pooled samples, after a pilot study which tested 148 samples pooled by 4 was conducted. The pooling algorithm was 100% (48 of 48) sensitive when samples were pooled by 4 and 98.4% (61 of 62) sensitive when samples were pooled by 10. Although 2.0% (2 of 99) of the negative pools of 4 and 7.1% (1 of 14) of the negative pools of 10 tested presumptive positive, all samples in these presumptive-positive pools were negative when retested individually, making the pooling algorithm 100% specific. In a population with 8% genital C. trachomatis prevalence, pooling by four would reduce costs by 39%. The model demonstrated that with a lower prevalence of 2%, pooling eight samples would reduce costs by 59%. Pooling urine samples for detection of C. trachomatis by LCR is sensitive, specific, and cost saving compared to testing individual samples.

Population-based study of fertility in women with HIV-1 infection in Uganda

BACKGROUND

To assess the effects of HIV-1 and other sexually transmitted infections on pregnancy, we undertook cross-sectional and prospective studies of a rural population in Rakai district, Uganda.

METHODS

4813 sexually active women aged 15-49 years were surveyed to find out the prevalence of pregnancy by interview and selective urinary human chorionic gonadotropin tests. The incidence of recognised conception and frequency of pregnancy loss were assessed by follow-up. Samples were taken to test for HIV-1 infection, syphilis, and other sexually transmitted diseases.

FINDINGS

At time of survey 757 (21.4%) of 3544 women without HIV-1 infection or syphilis were pregnant, compared with 46 (14.6%) of 316 HIV-1-negative women with active syphilis, 117 (14.2%) of 823 HIV-1-positive women with no concurrent syphilis, and 11 (8.5%) of 130 women with both syphilis and HIV-1 infection. The multivariate adjusted odds ratio of pregnancy in HIV-1-infected women was 0.45 (95% CI 0.35-0.57); the odds of pregnancy were low both in HIV-1-infected women without symptoms (0.49 [0.39-0.62]) and in women with symptoms of HIV-1-associated disease (0.23 [0.11-0.48]). In women with concurrent HIV-1 infection and syphilis the odds ratio was 0.28 (0.14-0.55). The incidence rate of recognised pregnancy during the prospective follow-up study was lower in HIV-1-positive than in HIV-1-negative women (23.5 vs 30.1 per 100 woman-years; adjusted risk ratio 0.73 [0.57-0.93]). Rates of pregnancy loss were higher among HIV-1-infected than uninfected women (18.5 vs 12.2%; odds ratio 1.50 [1.01-2.27]). The prevalence of HIV-1 infection was significantly lower in pregnant than in non-pregnant women (13.9 vs 21.3%).

INTERPRETATION

Pregnancy prevalence is greatly reduced in HIV-1-infected women, owing to lower rates of conception and increased rates of pregnancy loss. HIV-1 surveillance confined to pregnant women underestimates the magnitude of the HIV-1 epidemic in the general population.

Influence of endocervical specimen adequacy on PCR and direct fluorescent-antibody staining for detection of Chlamydia trachomatis infections

The cellular quality of the endocervical swab specimen used for the detection of Chlamydia trachomatis may dramatically impact the sensitivity of the diagnostic assay used. An evaluation of the adequacy of 319 endocervical swab specimens from women attending two inner-city sexually transmitted disease and family planning clinics, as well as five high school-based family planning clinics, was performed, and the resulting data were compared with the diagnostic results obtained by both Amplicor PCR and Microtrak direct fluorescent-antibody (DFA) staining. The swab from each patient was rolled across the open circular area of a DFA slide and then used to inoculate a transport tube for PCR (Roche), after which the swab was discarded. The slides were stained and examined by epifluorescence microscopy for the presence of C. trachomatis elementary bodies and for the presence and number of cell types to determine specimen adequacy. Cellular adequacy for a cervical swab specimen was defined as the presence of one or more columnar epithelial or metaplastic epithelial cells or the presence of more than 100 erythrocytes per high-power microscopic field. Of the 319 specimens read by DFA, 204 (63.9%) were determined to be adequate. There were 34 (10.7%) positive specimens by DFA and/or PCR. Twenty-nine (9.1%) specimens were positive by PCR, 20 (6.3%) specimens were DFA positive, and 15 (4.7%) were concordantly positive by both tests. The prevalence of chlamydia among adequate specimens was 14.2% (29/204), compared to 4.3% (5/115) for inadequate specimens (P < 0.0001). Variations in specimen quality and the sensitivity of the diagnostic assay used have a significant impact on determining the prevalence of C. trachomatis in a population.

HIV-1 infection associated with abnormal vaginal flora morphology and bacterial vaginosis

BACKGROUND

In-vitro research has suggested that bacterial vaginosis may increase the survival of HIV-1 in the genital tract. Therefore, we investigated the association of HIV-1 infection with vaginal flora abnormalities, including bacterial vaginosis and depletion of lactobacilli, after adjustment for sexual activity and the presence of other sexually transmitted diseases (STDs).

METHODS

During the initial survey round of our community-based trial of STD control for HIV-1 prevention in rural Rakai District, southwestern Uganda, we selected 4718 women aged 15-59 years. They provided interview information, blood for HIV-1 and syphilis serology, urine for detection of Chlamydia trachomatis and Neisseria gonorrhoeae, and two self-administered vaginal swabs for culture of Trichomonas vaginalis and gram-stain detection of vaginal flora, classified by standardised, quantitative, morphological scoring. Scores 0-3 were normal vaginal flora (predominant lactobacilli). Higher scores suggested replacement of lactobacilli by gram-negative, anaerobic microorganisms (4-6 intermediate; 7-8 and 9-10 moderate and severe bacterial vaginosis).

FINDINGS

HIV-1 frequency was 14.2% among women with normal vaginal flora and 26.7% among those with severe bacterial vaginosis (p < 0.0001). We found an association between bacterial vaginosis and increased HIV-1 infection among younger women, but not among women older than 40 years; the association could not be explained by differences in sexual activity or concurrent infection with other STDs. The frequency of bacterial vaginosis was similar among HIV-1-infected women with symptoms (55.0%) and without symptoms (55.7%). The adjusted odds ratio of HIV-1 infection associated with any vaginal flora abnormality (scores 4-10) was 1.52 (95% CI 1.22-1.90), for moderate bacterial vaginosis (scores 7-8) it was 1.50 (1.18-1.89), and for severe bacterial vaginosis (scores 9-10) it was 2.08 (1.48-2.94).

INTERPRETATION

This cross-sectional study cannot show whether disturbed vaginal flora increases susceptibility to HIV-1 infection. Nevertheless, the increased frequency of HIV-1 associated with abnormal flora among younger women, for whom HIV-1 acquisition is likely to be recent, but not among older women, in whom HIV-1 is likely to have been acquired earlier, suggests that loss of lactobacilli or presence of bacterial vaginosis may increase susceptibility to HIV-1 acquisition. If this inference is correct, control of bacterial vaginosis could reduce HIV-1 transmission.

Urine as a diagnostic specimen for the detection of Chlamydia trachomatis in Malaysia by ligase chain reaction

BACKGROUND AND OBJECTIVES

Noninvasive urine screening for Chlamydia trachomatis infections offers a valuable public health tool, which could be of vast importance in chlamydial control programs. The authors evaluated a new DNA amplification method, ligase chain reaction (LCR).

GOALS

The goal was to ascertain whether urine testing could be used as screening method to detect C. trachomatis infections in commercial sex workers, patients at sexually transmitted diseases clinic, and asymptomatic patients in Kuala Lumpur, Malaysia.

METHODS

First-void urine specimens from 300 men and 300 women were tested by LCR, as well as by a commercially available enzyme immunoassay. The LCR assay amplifies specific sequences within the chlamydial plasmid with ligand-labeled probes, and the resultant amplicons are detected by an automated immunoassay. Specimens with discrepant results were confirmed by another LCR of the specimen that targeted the gene for the major outer membrane protein (OMP1).

RESULTS

There were 31 LCR-positive male urine and 37 LCR-positive female urine specimens. The resolved sensitivity and specificity for the LCR of the male urine specimens were 100% and 99.6%, respectively, whereas for female urine specimens, the sensitivity and specificity were 100% and 98.5%, respectively. After resolution of discrepant test results by OMP1 LCR, the prevalence was 10% for men and 11% for women. The urine enzyme immunoassay was not useful in diagnosing C. trachomatis infections in either men or women, as the resolved sensitivities were 10% and 15.2%, respectively. The specificities were 99.6% for men and 98.9% for women.

CONCLUSIONS

Testing first-void urine specimens by LCR is a highly sensitive and specific method to diagnose C. trachomatis infections in men and women, providing health care workers and public health officials with a new molecular amplification assay that uses noninvasive urine specimens for population-based screening purposes.

Replication of Chlamydia pneumoniae in vitro in human macrophages, endothelial cells, and aortic artery smooth muscle cells

Chlamydia pneumoniae has recently been associated with atherosclerotic lesions in coronary arteries. To investigate the biological basis for the dissemination and proliferation of this organism in such lesions, the in vitro growth of C. pneumoniae was studied in two macrophage cell lines, peripheral blood monocyte-derived macrophages, human bronchoalveolar lavage macrophages, several endothelial cell lines, and aortic smooth muscle cells. Five strains of C. pneumoniae were capable of three passages in human U937 macrophages and in murine RAW 246.7 macrophages. Titers were suppressed in both macrophage types with each passage, as compared with growth titers in HEp-2 cells. Both human bronchoalveolar lavage macrophages and peripheral blood monocyte-derived macrophages were able to inhibit C. pneumoniae after 96 h of growth. Eleven C. pneumoniae strains were capable of replicating in normal human aortic artery-derived endothelial cells, umbilical vein-derived endothelial cells, and pulmonary artery endothelial cells. Infection in human aortic artery smooth muscle cells was also established for 13 strains of C. pneumoniae. The in vitro ability of C. pneumoniae to maintain infections in macrophages, endothelial cells, and aortic smooth muscle cells may provide support for the hypothesis that C. pneumoniae can infect such cells and, when infection is followed by an immune response, may contribute to atheroma formation in vivo. More studies are needed to investigate the complex relationship between lytic infection and persistence and the potential for C. pneumoniae to influence the generation of atheromatous lesions.

Failure to detect Chlamydia pneumoniae in coronary atheromas of patients undergoing atherectomy

To further investigate a proposed relationship between Chlamydia pneumoniae and coronary heart disease, coronary atheromas were collected from patients undergoing percutaneous atherectomy. Fifty-eight atheroma specimens were examined by culture and polymerase chain reaction (PCR) and 22 by electron microscopy. All were negative for C. pneumoniae, except a single specimen that was PCR-positive. These results differ from studies in other populations, in which this organism was identified by nonculture methods within coronary atheromas obtained at autopsy. Anti-C. pneumoniae antibody titers from 65 of the patients were compared with those of 28 asymptomatic controls. IgG titers were higher in controls than in patients. There is no evidence that C. pneumoniae exists within atheromas in this study population, nor does seroprevalence correlate with the presence of coronary disease in these patients.

Community-acquired pneumonia: impact of immune status

This cross-sectional and prospective one year study evaluated adults admitted to an inner city hospital with community-acquired pneumonia. The study used extensive diagnostic methods to evaluate the etiologies of community-acquired pneumonia in hospitalized patients with differing immunologic status. Of 385 study patients, concurrent problems associated with immunosuppression were noted in 221 (57%) patients, 180 of whom were human immunodeficiency virus (HIV)-infected. The five most common causes of community-acquired pneumonia were: Streptococcus pneumoniae, Pneumocystis carinii, aspiration, Hemophilus influenzae, and gram-negative bacilli. Only 8.3% of patients had either Legionella, Chlamydia pneumoniae or Mycoplasma pneumoniae. Despite use of state-of-the-art diagnostic techniques, no diagnosis was made in 46 of 180 (25.6%) HIV-infected patients, 56 of 164 (34.1%) immunocompetent patients, and 20 of 41 (48.8%) non-HIV-infected immunosuppressed patients. The diagnostic yield of pre-antibiotic sputum culture for conventional bacteria was 99/155 (63.9%) compared to 52 of 169 patients (32.7%) with adequate post-antibiotic sputum culture (p < 0.0001). Although S. pneumonia continues to be the most commonly identified etiologic agent of community-acquired pneumonia, it is surpassed by P. carinii in the HIV-infected patient population. The apparent decline in the frequency of S. pneumoniae in our series presumably reflects administration of antibiotics prior to procurement of sputum culture. The paucity of atypical agents in this study support the current American Thoracic Society guidelines for selective use of macrolide therapy in immunocompetent adults hospitalized with community-acquired pneumonia.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of Chlamydia pneumoniae growth in HEp-2 cells pretreated with gamma interferon and tumor necrosis factor alpha

An in vitro culture system was used to study the effects of increasing concentrations of human cytokines on the intracellular replication of Chlamydia pneumoniae. HEp-2 cell monolayers, pretreated for 24 h with 200 U of human recombinant gamma interferon (IFN-gamma) per ml restricted the intracellular replication of C. pneumoniae. Tumor necrosis factor alpha (TNF-alpha; 25 ng/ml) exhibited a synergistic effect with IFN-gamma by reducing the concentration of IFN-gamma necessary to restrict intracellular growth to 100 U/ml. The addition of 200 micrograms of tryptophan per ml significantly reversed the inhibitory effects of IFN-gamma and TNF-alpha, suggesting involvement of the indoleamine-2,3-dioxygenase pathway in the restriction process.

Adenovirus vaccines in the U.S. military

Acute respiratory disease (ARD) due to adenoviruses caused significant morbidity in military training populations. Since 1971 ARD has been controlled by the use of live, enteric-coated, adenovirus (ADV) types 4 and 7 vaccines. This immunization program overcame significant problems in vaccine development. Due to a production delay, military training posts stopped ADV vaccine administration in spring 1994. The delivery of ADV vaccine resumed in late February 1995, but another production delay is anticipated. A generation of military medical people have not been exposed to the significant morbidity caused by adenoviruses and are unaware of the effectiveness of the ADV vaccine. ARD morbidity before ADV vaccines, the ADV vaccine development program, and current issues regarding the control of ARD due to adenoviruses in the military are discussed.

Prevalence of asymptomatic nasopharyngeal carriage of Chlamydia pneumoniae in subjectively healthy adults: assessment by polymerase chain reaction-enzyme immunoassay and culture

Although Chlamydia pneumoniae is a well-described and common respiratory tract pathogen, up to 90% of infections with this organism are thought to be asymptomatic. Because asymptomatic infection with C. pneumoniae has not been studied in a systematic manner, we conducted a prospective study of healthy adults to establish the prevalence of asymptomatic infection. Nasopharyngeal swab specimens were obtained from 104 subjectively healthy people and evaluated by culture and polymerase chain reaction-enzyme immunoassay (PCR-EIA) for the presence of the organism. Serum obtained from 103 of these individuals was tested by microimmunofluorescence for the titer of specific antibody to C. pneumoniae. For two individuals, C. pneumoniae was identified in nasopharyngeal specimens by culture and/or PCR-EIA; one of these individuals had an IgG titer of 1:256, whereas the other had no detectable antibody. Of the remaining 101 individuals with negative culture and PCR-EIA results, 19 fulfilled presently accepted serological criteria for acute infection; i.e., the IgM titer was > or = 1:16, the IgG titer was > or = 1:512, or both. On the basis of our findings, we conclude that asymptomatic upper airway infection and carriage with C. pneumoniae occur among subjectively healthy persons; we also propose that such individuals may represent a reservoir for this organism in the community. Further, this study demonstrates that currently available diagnostic tests for C. pneumoniae may be unable to accurately distinguish between infection responsible for respiratory tract disease and that representing carriage.

Diagnosis of Chlamydia pneumoniae infection in patients with community-acquired pneumonia by polymerase chain reaction enzyme immunoassay

We conducted a prospective study of 385 patients who had community-acquired pneumonia with use of a modified polymerase chain reaction (PCR) assay that detects amplified DNA by enzyme immunoassay (EIA). We used PCR-EIA to improve detection of Chlamydia pneumoniae infection and to differentiate C. pneumoniae infection from other chlamydial infections. Cultures of throat swab specimens from four patients yielded Chlamydia species (C. pneumoniae, one patient; Chlamydia species, two patients; and C. psittaci, one patient). C. pneumoniae was repeatedly detected by PCR-EIA for thirteen (3.4%) of these 385 patients. Six of these 13 patients were infected with the human immunodeficiency virus. Ten (76.9%) of the patients who were positive by PCR-EIA had IgG titers of > or = 1:16, and two (15.4%) of the 13 patients had IgG titers of < 1:16; no sera was available in one case. Other pathogens were recovered in eight (61.5%) of the 13 cases in which C. pneumoniae was detected by PCR-EIA. In addition, for 46 (11.9%) of the 385 patients the titers of antibody were considered diagnostic of C. pneumoniae infection; however, as 36 of the 46 patients were infected with the human immunodeficiency virus (which may have affected their serological response to C. pneumoniae), interpretation of these titers was problematic. As PCR-EIA was more sensitive than was culture for detecting C. pneumoniae infection in this study, this method may be a valuable tool for the prompt diagnosis of this infection.

Diagnostic utility of PCR-enzyme immunoassay, culture, and serology for detection of Chlamydia pneumoniae in symptomatic and asymptomatic patients

To assess the utility of PCR-enzyme immunoassay (EIA) for diagnosis of acute infection with Chlamydia pneumoniae, we compared tissue culture, PCR-EIA, direct fluorescent-antibody (DFA) stain, and serology in studies with 56 patients with respiratory symptoms and 80 asymptomatic persons. Thirty-five patients were positive by either culture or PCR-EIA, and 101 were negative by both assays. Thirty specimens from symptomatic patients and one from an asymptomatic patient were culture positive; 23 of these were also PCR-EIA positive. Of the eight culture-positive, PCR-EIA-negative specimens, five were DFA negative and three were DFA positive. Four additional specimens were culture negative and PCR-EIA positive; of these, three were DFA positive and one was DFA negative. When we used culture- and/or DFA-positive results as a reference or "gold standard," the sensitivity and specificity of PCR were 76.5 and 99.0%, respectively. When we used PCR- and/or DFA-positive results as the reference, the sensitivity of culture was 87.5%. On the basis of single acute serum specimens, only 8 of these 35 patients had diagnostic antibody titers. Of the asymptomatic patients, 75% had immunoglobulin G or immunoglobulin M antibody to C. pneumoniae; 15 (18.8%) of these had antibody levels considered to be diagnostic of acute infection. This multicenter study indicates that culture and/or PCR-EIA is more reliable for prompt diagnosis of C. pneumoniae infection than single-point serology alone.

Detection of Chlamydia pneumoniae by polymerase chain reaction-enzyme immunoassay in an immunocompromised population

Chlamydia pneumoniae has now been associated with pneumonia, bronchitis, pharyngitis, acute chest syndrome of sickle cell disease, and asthma. Because of the difficulty of primary isolation and tissue-culture adaptation of this organism, we used a previously developed polymerase chain reaction-enzyme immunoassay (PCR-EIA) to screen 132 culture-negative bronchoalveolar lavage (BAL) specimens from 108 immunocompromised patients (34% of whom were positive for human immunodeficiency virus) and 7 healthy volunteers. Thirteen specimens (9.8%) from 12 immunocompromised patients (11.1%) gave a positive result; one patient had two positive specimens obtained 3 days apart. No healthy volunteer had a PCR-EIA-positive BAL specimen. Twelve (11.1%) of the immunocompromised patients also had diagnostic levels of antibody. Four patients had positive results in both PCR-EIA and serological tests. Thus 20 (18.5%) of the 108 patients had laboratory evidence of C. pneumoniae infection. These data indicate that diagnosis of acute infection with C. pneumoniae can be established more rapidly and reliably by PCR-EIA than by culture or serology, particularly among immunocompromised patients, in whom serological changes in response to infection are relatively undependable. With an infection rate of 11.1% according to PCR-EIA, C. pneumoniae should be considered in the evaluation and treatment of pneumonia in immunocompromised patients.

Rapid diagnosis of Chlamydia psittaci pneumonia

Two cases of Chlamydia psittaci pneumonia are presented. In each, a rapid diagnosis was made through the use of direct immunofluorescent antibody staining of respiratory secretions with monoclonal antibodies to chlamydial antigens. In one case the diagnosis was confirmed by the isolation of the causative organism from sputum and a pharyngeal swab. Chlamydial lipopolysaccharide was detectable in sputum from this patient in an enzyme immunoassay. Serological responses to C. psittaci, Chlamydia trachomatis, and Chlamydia pneumoniae were evaluated, and serological cross-reactivity was observed between each species. Rapid antigen detection systems for Chlamydia species that use commercially available reagents can be helpful in the evaluation of selected patient populations.

Phylogenetic relationship of Chlamydia pneumoniae to Chlamydia psittaci and Chlamydia trachomatis as determined by analysis of 16S ribosomal DNA sequences

The 16S ribosomal DNA sequence of Chlamydia pneumoniae was determined and compared with the corresponding gene sequences of Chlamydia psittaci and Chlamydia trachomatis. C. pneumoniae has been reported to exhibit little chromosomal DNA homology with the other chlamydial species, and its phylogenetic relationships within the genus Chlamydia have not been described. A polymerase chain reaction was employed to determine the 16S rRNA gene sequence of C. pneumoniae. Ten primers from the C. psittaci sequences were used to amplify a C. pneumoniae template in overlapping segments of the gene. Sequence data for 1,554 bases indicated that the levels of homology of C. pneumoniae with C. psittaci and C. trachomatis were 96.19 and 94.07%, respectively. These data support the results of previous biochemical and developmental studies indicating that C. pneumoniae is more closely related to C. psittaci than to C. trachomatis.

Direct detection of Chlamydia trachomatis in urine specimens from symptomatic and asymptomatic men by using a rapid polymerase chain reaction assay

Screening for Chlamydia trachomatis infection in men has traditionally been limited to men who present with urethral symptoms, thereby limiting the detection of asymptomatic chlamydia infection in men. In order to effectively screen both symptomatic and asymptomatic men, we evaluated a newly developed polymerase chain reaction (PCR) assay, Amplicor C. trachomatis, from Roche Molecular Systems for the detection of C. trachomatis in urine specimens in comparison with urethral culture. A total of 530 male urine specimens were collected from 322 symptomatic and 208 asymptomatic men attending two sexually transmitted disease clinics in Baltimore, Md. The prevalence of C. trachomatis by culture was 9.8% (10.6% in symptomatic men and 8.2% in asymptomatic men). Compared with culture, the sensitivity of the PCR was 92.8%, the specificity was 94.7%, the positive predictive value was 68.4%, and the negative predictive value was 99.1%. Discrepant results between culture and PCR were further analyzed by direct fluorescent-antibody staining of elementary bodies in urine sediment and in culture transport vials and by major outer membrane protein PCR of transport media for specimens with negative culture. The revised sensitivity and specificity of PCR for urine were 95.0 and 99.8%, respectively, and the positive and negative predictive values were 98.7 and 99.1%, respectively. The sensitivity of culture compared with PCR and/or direct fluorescent-antibody staining was 68.4%. These results indicate that the PCR assay is a highly sensitive and specific assay for the detection of C. trachomatis in male urine specimens and provides a noninvasive technique for routine screening of chlamydia infection in both symptomatic and asymptomatic men.

Similarity of Chlamydia pneumoniae strains in the variable domain IV region of the major outer membrane protein gene

DNA was amplified by polymerase chain reaction from the gene encoding the major outer membrane protein (MOMP) of Chlamydia pneumoniae in order to examine the relatedness of strains isolated from diverse geographical regions. Primers for this reaction were chosen to span a 207-bp region comparable to that of the fourth variable segment of the MOMP gene of Chlamydia trachomatis. Among C. trachomatis, sequence heterogeneity is characteristic within variable sequence domain IV (VDIV) and correlates with serovar type. In contrast, sequence analysis of polymerase chain reaction products from 13 C. pneumoniae isolates indicated that all tested strains were identical in this segment of the MOMP gene. The predicted amino acid sequences from the C. pneumoniae VDIV gene products shared only 13.3 to 30% homology with published VDIV regions from serovars of C. trachomatis. Homology of these VDIV amino acid sequences with sequences from strains of C. psittaci ranged from 45.7 to 60%. The sequence conservation of the VDIV region of the MOMP gene indicates that C. pneumoniae strains may be more genetically homogeneous than C. trachomatis or Chlamydia psittaci strains. Future investigations of antigenic diversity among C. pneumoniae strains should be aimed at the evaluation of variation in other regions of the C. pneumoniae genome.

Gene typing of Chlamydia trachomatis by polymerase chain reaction and restriction endonuclease digestion

A portion of the major outer membrane protein (MOMP) gene from 15 Chlamydia trachomatis serovars was amplified by polymerase chain reaction (PCR) and the product was analyzed by restriction fragment length polymorphism (RFLP). A set of primers was used to amplify an 871 base pair gene fragment encompassing the 4 hypervariable regions of MOMP. AluI digestion of the product gave distinctive patterns for the 15 serovars as demonstrated on silver-stained polyacrylamide gels. A triple digest with EcoRI, HinfI, and HpaII allowed improved discrimination between closely related serovars (C, H, I, J, L3). PCR and RFLP were used to type 50 wild-type clinical isolates and results were compared to results of the solid-phase enzyme immunoassay typing method. These isolates represented the most prevalent genital serovars (D, E, F, K, I and J) in the local sexually transmitted diseases clinic population. For specimens containing 1 serovar, the results of the two methods were similar for 42 samples and discordant for 1 sample. In addition, two samples showed evidence of mixed infection with two serovars as identified by both methods. Five additional specimens contained two serovars, as shown by one or both methods. In all five such specimens, the two typing methods agreed on at least one of the two serovars. For both single and multiple serovar specimens, there was concordance between the two typing methods for 16/17 E serovars, 8/9 D serovars, 8/8 F serovars, 7/7 I serovars, 7/7 J serovars, 5/8 K serovars, and 0/2 G serovars.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of Chlamydia pneumoniae by DNA amplification of the 16S rRNA gene

Chlamydia pneumoniae is an important cause of respiratory disease in humans, but diagnosis of C. pneumoniae is hindered by difficulties in the in vitro growth of the organism. In order to improve detection and identification, we recently developed a polymerase chain reaction (PCR) assay which uses oligonucleotide primers specific for C. pneumoniae. The nucleic acid sequence was determined for the 16S rRNA of C. pneumoniae, and regions in which C. pneumoniae differed from both Chlamydia psittaci and Chlamydia trachomatis were identified. Oligonucleotide primers corresponding to these unique regions were then synthesized and used in a PCR for the detection of C. pneumoniae. The C. pneumoniae-specific primers permitted the identification of six isolates of C. pneumoniae, but no reaction was observed with the 15 serovars of C. trachomatis or two strains of C. psittaci. PCR should prove to be valuable in confirming the identification of C. pneumoniae and in the diagnosis of C. pneumoniae infections.

In vitro evaluation of activities of azithromycin, erythromycin, and tetracycline against Chlamydia trachomatis and Chlamydia pneumoniae

The in vitro activities of azithromycin (CP-62,993; Pfizer), erythromycin, and tetracycline were evaluated by inhibiting Chlamydia trachomatis and Chlamydia pneumoniae, formerly TWAR, propagation in vitro in McCoy cells, HeLa cells, and HL cells. Eleven clinical isolates of C. trachomatis (serovars D, E, F, J, K, and L2) and four strains of C. pneumoniae were tested with an inoculum of 10(3) inclusion-forming units in a 96-well microtiter plate. The MIC ranges of these antimicrobial agents against C. trachomatis were as follows: azithromycin, 0.125 to 0.5 microgram/ml; erythromycin, 0.25 to 0.1 microgram/ml; and tetracycline, 0.0625 to 1.0 microgram/ml. The MBC ranges, calculated from passage into antibiotic-free medium, were as follows: azithromycin, 0.125 to 4.0 micrograms/ml; erythromycin, 0.5 to 8.0 micrograms/ml; and tetracycline, 0.0625 to 4.0 micrograms/ml. The MIC ranges for C. pneumoniae in both HeLa and HL cells were as follows: azithromycin, 0.125 to 1.0 micrograms/ml; erythromycin, 0.0625 to 1.0 microgram/ml; and tetracycline, 0.125 to 1.0 microgram/ml. The MBC ranges were as follows: azithromycin, 0.25 to 1.0 microgram/ml; erythromycin, 0.25 to 1.0 microgram/ml; and tetracycline, 0.125 to 4.0 micrograms/ml. From the results of this in vitro study, azithromycin appears to be an effective antibiotic comparable to tetracycline and erythromycin for use in the treatment of both C. trachomatis and C. pneumoniae infections.

Detection and differentiation of Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae by DNA amplification

The polymerase chain reaction was used to detect major outer membrane protein (MOMP) gene sequences from the three species of Chlamydia. Using three primer pairs and one restriction enzyme digestion, three distinct genotypes, corresponding to the three species, Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci, were demonstrated. C. trachomatis was amplified by all three primer pairs and the amplified fragment was digested by EcoRI. C. pneumoniae was amplified by only two of the three primer pairs, and the amplified fragment was digested by EcoRI. C. psittaci was amplified by only two of the pairs and the amplified fragment was EcoRI-resistant. C. trachomatis was detected in direct patient specimens, tissue culture specimens, and fixed specimens, and all serovars of C. trachomatis were detectable. The polymerase chain reaction can detect and differentiate the three species of Chlamydia and may prove a valuable diagnostic tool.

Evaluation of Syva enzyme immunoassay for detection of Chlamydia trachomatis in genital specimens

Detection of Chlamydia trachomatis infection was evaluated by culture and a new Syva enzyme immunoassay (EIA) in 1,012 patients at two Baltimore, Md., sexually transmitted disease clinics. The overall chlamydia prevalence determined by culture was 12%. For 506 fresh cervical and urethral specimens, the sensitivity of Syva EIA was 90% and its specificity was 94% compared with culture. Discordant Syva EIA results were further evaluated by staining the sediment in centrifuged culture transport media and Syva EIA transport tubes with a fluorescent monoclonal antibody to C. trachomatis to detect elementary bodies. Reanalysis of the data after use of this technique to resolve discordant results increased sensitivity and specificity to 92 and 96%, respectively. A subsample of 307 fresh cervical specimens was also tested in a three-way comparison using Abbott Chlamydiazyme, Syva EIA, and culture. In this sample, compared with culture, the sensitivity and specificity of Syva EIA were 87 and 95%, respectively, and for Chlamydiazyme they were 77 and 98%, respectively. Syva EIA is a 4-h, easy-to-perform enzyme-linked immunosorbent assay which has a high sensitivity with fresh genital specimens and offers an excellent alternative to culture.

Evaluation of Abbott Testpack Chlamydia for detection of Chlamydia trachomatis in patients attending sexually transmitted diseases clinics

This work compares a rapid solid-phase EIA (Abbott TestPack Chlamydia) to tissue culture and a direct fluorescent antibody test (Syva Microtrak) for detection of C. trachomatis in 436 patients attending two inner-city sexually transmitted diseases (STD) clinics. The prevalence of C. trachomatis by culture was 12% (5% in men, 15% in women). Overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TestPack compared to culture were 70%, 98%, 80%, and 96% respectively. In men, 12 specimens were positive by TestPack, while only eight specimens were positive by culture. Six TestPack-positive, culture-negative specimens were further evaluated by centrifugation of culture transport media and examination of the sediment for chlamydia elementary bodies (EBs) using fluorescent monoclonal antibodies to C. trachomatis. Using this procedure, five of six culture negative specimens contained EBs (revised sensitivity 85%, specificity 99%, PPV 92%, NPV 99%). In 285 women evaluable in culture and TestPack, 44 (15%) specimens were culture positive; TestPack was positive in 29 (sensitivity 66%) culture positive women. Of 241 culture negative patients, 238 had negative TestPack results (specificity 99%) and no EBs were detected in the culture-negative, TestPack-positive specimens. Twenty-three (8%) Microtrak specimens were unsatisfactory for testing; two of these were culture and TestPack positive. Therefore, of 263 specimens evaluable using Microtrak, 42 (16%) specimens were culture positive; Microtrak was positive in 32 (sensitivity 76%) culture-positive women. Abbott TestPack Chlamydia is a rapid (25 minute), visually read format requiring no specialized equipment for detection of chalmydia infections with a sensitivity comparable to that of Microtrak.

Evaluation of a latex agglutination test for Clostridium difficile in two nursing home outbreaks

The Culturette Brand Clostridium difficile test (CDT; Marion Laboratories, Inc., Kansas City, Mo.) is a latex agglutination test for C. difficile. The recent controversy involving the identity of antigens detected by CDT has made decisions on its use difficult. We compared the test results with those of selective culture and stool cytotoxin assays in investigations of two nursing home outbreaks of C. difficile-associated disease in order to formulate usage recommendations. Selective culture for C. difficile identified 27 (19%) of 142 subjects as carriers. CDT and the stool cytotoxin assay identified only 52 and 48% of these carriers, respectively. Compared with the stool cytotoxin assay, CDT had a high sensitivity (92%) and specificity (89%) for the detection of C. difficile disease, but the positive predictive value of the test was only 17% when the prevalence of disease was 2%. We conclude that the CDT should not be used to identify carriers but that it is a sufficiently sensitive and specific screening test for diagnosing C. difficile disease. However, since the positive predictive value of the CDT is low when the prevalence of disease is low, positive test results should be confirmed by the stool cytotoxin assay.

Comparison of the Phadebact Gonococcus Test with the rapid fermentation method

The Phadebact Gonococcus Test (Pharmacia Diagnostics, Piscataway, N.J.), a coagglutination technique, was compared with the rapid fermentation method of Kellogg and Turner (D. S. Kellogg, Jr., and E. M. Turner, Appl. Microbiol. 25: 550--552, 1973). A total of 93 organisms isolated on Martin-Lewis media were determined to be Neisseria gonorrhoeae based on the following criteria: presence of gram-negative diplococci, oxidase positivity, and appropriate reaction in the rapid fermentation method. These 93 isolates were then serologically tested with the Phadebact test. The direct method was attempted on the first 46 N. gonorrhoeae isolates. Difficulty in interpreting results was encountered in 39%. Thereafter, the alternate method of boiling was instituted on an additional 47 N. gonorrhoeae isolates, with 2 isolates producing noninterpretable results. All 93 isolates were frozen for a maximum of 2 months in skim milk at -25 degrees C. These isolates were thawed and retyped with the alternate boiling procedure, with 97% being confirmed as N. gonorrhoeae. In addition, 33 Neisseria meningitidis isolates, 14 Neisseria species, and 7 Moraxella species were tested with similar techniques. No positive reactions were observed. A cost effectiveness study using 5, 10, and 20 microliters of the gonococcal reagent was undertaken to reduce the cost of the test. When 10 and 20 microliters of reagent were used, no difficulty was encountered in interpreting the reaction. The coagglutination technique was difficult to read when 5 microliters of reagent was used.

Serum gentamicin assay by a radiometric procedure

A new radiometric (BACTEC) microbiologic procedure, using a 14C-urea substrate and a Proteus species culture, was compared with three microbiologic assays and a radioimmunoassay (RIA) method for determination of gentamicin levels in serum. The non-radiometric microbiologic assays did not differ significantly from the RIA assay, but the BACTEC method showed significant differences with specimens containing greater than 4 microgram/ml gentamicin. Overall, the BACTEC assay was found to be simple to run, fast and reproducible. At concentrations of gentamicin less than 4 microgram/ml, it was just as accurate as were the microbiologic assays. However, at concentrations greater than 4 microgram/ml, the BACTEC assay read consistently less than RIA and the other assays. Because of the BACTEC assay's high cost per single test, it cannot approach the utility of the rapid, easy, reliable, and comparatively inexpensive microbiologic assays. The BACTEC assay is, however, a useful alternative to the RIA method in laboratories that already have radiometric equipment and in which batching of serum samples for gentamicin assay is necessary.

Selective and enhanced recovery of group A and B streptococci from throat cultures with sheep blood agar containing sulfamethoxazole and trimethoprim

Sheep blood agar containing 23.75 microgram of sulfamethoxazole and 1.25 microgram of trimethoprim (SXT-BA) per ml was compared with conventional sheep blood agar (SBA) for isolating group A and B streptococci from throat cultures. This selective medium allowed much better recovery of group A and B streptococci and suppressed the growth of the normal flora, including "viridans" streptococci. In an initial study of 700 throat cultures, SXT-BA recovered 42% more group A and 49% more group B streptococci than did SBA. When SXT-BA was introduced into the routine microbiology laboratory and used by a number of medical technologists. SXT-BA recovered 28% more group A and 37% more group B streptococci than did SBA. In addition, the selective medium inhibited 83% of the non-group A and B streptococci that were recovered by SBA.