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PubMed1980

[Identification of Chlamydia trachomatis in cell culture (author's transl)].

The method for the identification of Chlamydia trachomatis in tissue culture described by Hobson was slightly modified and tested as to its usefullness for routine-diagnostic. Cervical swabs of 74 prostitutes and 100 unselected gynecological outpatients were examined for Chlamydia trachomatis. The isolation of Chlamydia was carried out by McCoy cell culture; the inclusions were identified by Giemsa and Lugol's train procedure. The isolation rate of Chlamydia trachomatis was 17% in the group of the prostitutes, whereas in the group of unselected women no Chlamydia were detected. The correspondence of our findings with previous results indicates the applicability of the method used.

Animals↗
PubMed2002

Uptake and processing of Chlamydia trachomatis by human dendritic cells.

Chlamydia trachomatis (CT) causes several sexually transmitted diseases. In 2-5% of cases, CT infection leads to the development of reactive arthritis. Dendritic cells (DC) are central in T cell priming and the induction of antigen specific immunity. Here we have studied the uptake and processing of CT serovar L2 by human DC, and their ability to present CT antigens to both CD4(+) and CD8(+) T cells. We show that the entry of CT was mediated by the attachment of CT to heparan sulfates and could be inhibited by heparin. There was no inhibition of uptake by an agent which blocks micropinocytosis. Infecting DC with CT led to their activation and the production of IL-12 and TNF-alpha but not IL-10. Following invasion, CT was confined to distinct vacuoles which were visualized with anti-CT antibodies using confocal microscopy. Unlike with epithelial cells, these vacuoles did not develop into characteristic inclusion bodies. In the first 48 h, CT(+) vacuoles were negative for Lamp-1 and MHC class II. Despite no obvious co-localization between CT vacuoles and MHC loading compartments, infected DC efficiently presented CT antigens to CD4(+) T cells. Infected DC also expanded CT specific CD8(+) T cells, allowing us to generate a number of CT-reactive CD8(+) T cell clones. There is still controversy about the importance of chlamydia-specific CD8(+) T cell responses in patients with arthritis. This is largely due to the difficulties in studying CTL responses at the clonal level. The use of DC as antigen-presenting cells should enable more detailed characterization of these CTL responses.

Amiloride↗
PubMed1995

The inflammatory cytokine response to Chlamydia trachomatis infection is endotoxin mediated.

Chlamydia trachomatis is a major etiologic agent of sexually transmitted diseases. Although C. trachomatis is a gram-negative pathogen, chlamydial infections are not generally thought of as endotoxin-mediated diseases. A molecular characterization of the acute immune response to chlamydia, especially with regard to the role of its lipopolysaccharide (LPS), remains to be undertaken. We extracted 15 mg of LPS from 5 x 10(12) C. trachomatis elementary bodies (EB) for analysis of structure and biological activity. When methylated lipid A was subjected to high-pressure liquid chromatography followed by mass spectrometry, the majority of the lipid A was found to be pentaacyl. The endotoxin activities of whole C. trachomatis EB and purified LPS were characterized in comparison with whole Salmonella minnesota R595 and with S. minnesota R595 LPS and lipooligosaccharide from Neisseria gonorrhoeae. Both C. trachomatis LPS and whole EB induced the release of tumor necrosis factor alpha from whole blood ex vivo, and C. trachomatis LPS was capable of inducing the translocation of nuclear factor kappa B in a Chinese hamster ovary fibroblast cell line transfected with the LPS receptor CD14. In both assays, however, C. trachomatis was approximately 100-fold less potent than S. minnesota and N. gonorrhoeae. The observation that C. trachomatis is a weak inducer of the inflammatory cytokine response correlates with the clinical observation that, unlike N. gonorrhoeae infection, genital tract infection with C. trachomatis is often asymptomatic. The ability of specific LPS antagonists to completely inhibit the tumor necrosis factor alpha-inducing activity of whole C. trachomatis EB suggests that the inflammatory cytokine response to chlamydia infection may be mediated primarily through LPS. This implies that the role of other surface protein antigens, at least in terms of eliciting the proinflammatory cytokine response, is likely to be minor.

Antigens, CD↗
PubMedDate not supplied

Chlamydia trachomatis: impact on human reproduction.

Chlamydia trachomatis infections are the most prevalent bacterial sexually transmitted infections (STI) recognized throughout the world. Worldwide, the magnitude of morbidity associated with sexually transmitted chlamydial infections is enormous. C.trachomatis is a common cause of urethritis and cervicitis, and sequelae include pelvic inflammatory disease (PID), ectopic pregnancy, tubal factor infertility, epididymitis, proctitis and reactive arthritis. The sharp worldwide increase in the incidence of PID during the past two decades has led to the secondary epidemics of tubal factor infertility and ectopic pregnancy. Chlamydial PID is the most important preventable cause of infertility and adverse pregnancy outcome. Chlamydial infections, like STI in general, are primarily a woman's health care issue since the manifestations and consequences are more damaging to the reproductive health in women than in men. Based on the available evidence, approximately 20% of women with chlamydial lower genital tract infection will develop PID, approximately 4% develop chronic pelvic pain, 3% infertility, and 2% adverse pregnancy outcome. However, these estimates are based on relatively weak evidence. Research on the link between C.trachomatis and male aspects of infertility has been much more limited. Currently recommended treatment regimens include azithromycin in a single dose or doxycycline for 7 days. These therapies are highly efficacious. Timely management of sex partners is essential for decreasing the risk for re-infection. Immunopathogenesis of C.trachomatis infection is one of the main focal points of current research into Chlamydia. Chlamydial infection fills the general prerequisites for disease prevention by screening, i.e. chlamydial infections are highly prevalent, usually asymptomatic, are associated with significant morbidity, can be reliably diagnosed, and are treatable. Screening programmes for C.trachomatis will be of paramount importance in the prevention of long-term sequelae. The cost of screening is only a fraction of the health care costs incurred due to complications resulting from undiagnosed and untreated chlamydial infections. Current strategies to control C.trachomatis still largely depend on clinic-based screening of symptomatic patients, and have not been successful. The development of highly sensitive and specific nucleic acid amplification tests for the diagnosis of chlamydial infections has been an important advance in the ability to conduct population-based screening programmes to prevent complications. Thus, the case for screening is clearly made, but much detail remains to be worked out.

Animals↗
PubMed1990

Amoxicillin therapy for Chlamydia trachomatis in pregnancy.

For treating Chlamydia trachomatis cervical infection in pregnancy, the Centers for Disease Control guidelines recommend either erythromycin base or erythromycin ethylsuccinate. There is no alternate therapy. Because of compliance problems with erythromycin regimens due to gastrointestinal side effects, such an alternative is needed. For this reason, we compared, in an open trial, the efficacy and patient compliance of amoxicillin (500 mg three times a day for 7 days) with those of erythromycin base (500 mg four times a day for 7 days) in treating C trachomatis cervical infections during pregnancy. In the amoxicillin group, 63 of 64 women (98.4%) had negative cervical cultures after treatment, compared with 55 of 58 women (94.8%) treated with erythromycin base. Vertical transmission to the infants was assessed by culture and/or persistent or rising immunoglobulin G antichlamydial antibody. In the amoxicillin group, 37 of 39 infants (94.9%) had no evidence of chlamydial infection, compared with 32 of 36 infants (88.8%) in the erythromycin group. These differences were not significant. The frequency of side effects was higher with erythromycin base than with amoxicillin (15 versus 8%), although not significantly so. However, the frequency of stopping medication because of side effects was significantly higher with erythromycin base than with amoxicillin (13 versus 2%; P less than .006). These results suggest that amoxicillin may be an acceptable alternative treatment for chlamydial infections in pregnancy.

Adult↗
PubMed1985

Effect of proteolytic cleavage of surface-exposed proteins on infectivity of Chlamydia trachomatis.

The proteolytic cleavage of Chlamydia trachomatis LGV-434 surface proteins and resultant effects on infectivity and association with cultured human epithelial (HeLa) cells have been examined. Of several proteases examined, trypsin, chymotrypsin, and thermolysin extensively cleaved the chlamydial major outer membrane protein (MOMP). Two proteases, trypsin and thermolysin, cleaved the MOMP to the extent that monomeric MOMP was not detectable by immunoblotting with monospecific polyclonal antibodies. In the case of thermolysin, not even antigenic fragments were detected. Surprisingly, infectivity toward HeLa cells was not diminished. In addition, the association of intrinsically 14C-radiolabeled elementary bodies (EBs) with HeLa cells or their dissociation by proteinase K was not measurably affected by prior trypsinization of the EBs. Trypsinization of lactoperoxidase surface-iodinated elementary bodies demonstrated that most of the 125I-labeled surface proteins were cleaved. In all cases, however, a number of proteolytic cleavage fragments remained associated with the EB surface after surface proteolysis. When trypsinized EBs were electrophoresed under nonreducing conditions and immunoblotted with either polyclonal or type-specific monoclonal MOMP antibodies, MOMP was found in a large oligomeric form that failed to enter the polyacrylamide stacking gel. Additionally, trypsinized viable EBs bound radioiodinated type-specific MOMP monoclonal antibody as efficiently as did the control nontrypsinized organisms. Taken together, the findings indicate that although the MOMP is highly susceptible to surface proteolysis, the supramolecular structure of the protein on the EB surface is apparently maintained by disulfide interactions. Thus, if surface-exposed chlamydial proteins are involved in the initial interaction of chlamydiae with eucaryotic cells, the functional domains of these proteins which mediate this interaction must be resistant to proteolysis and remain associated with the EB surface.

Antigens, Bacterial↗
PubMedDate not supplied

Prevalence of Chlamydia trachomatis infection in pregnant patients.

Chlamydia is a sexually transmitted disease of epidemic proportions, infecting an estimated 4 million people a year. It results not only in infertility and ectopic pregnancy but also in infant morbidity and mortality. Ectopic pregnancy is responsible for 11 percent of maternal deaths. About 60 percent of infected women can transmit the bacteria at birth to their infants. Early detection and treatment of chlamydia in both men and women, especially prenatal women, is critical. Chlamydia trachomatis infection of the cervix was found in 8.1 percent of a group of 1,004 pregnant women at a hospital prenatal clinic by means of a direct fluorescent antibody test. The prevalence of C. trachomatis was only 0.7 percent in 277 pregnant women receiving prenatal care from private practitioners. All patients between 27 and 30 weeks gestation who tested positive were treated with oral erythromycin. Their partners were treated with tetracycline. The outcome of pregnancy in patients treated for chlamydial infection was compared with a control group of noninfected mothers from the same population. The frequency of premature rupture of the membranes, prematurity, and low Apgar scores among the treated women were not significantly different from those in the control group. There was a significant difference, however, between the two groups in the incidence of low mean birth weight infants and the presence of meconium. Children can acquire a chlamydial infection at birth from contact with infected cervico-vaginal secretions. If not detected and treated, these infected infants may develop conjunctivitis, bronchiolitis, and pneumonia. It is suggested, therefore, that all patients at prenatal clinics be screened for chlamydial cervicitis. Those testing positive and their partners should be treated.

Adult↗
PubMedDate not supplied

[Evaluation of the effectiveness of a program of detection of asymptomatic Chlamydia trachomatis infection in women].

BACKGROUND: Chlamydia Trachomatis is at present the most prevalent pathogenic agent among the causes of sexually transmitted diseases in developed countries, and has reached epidemic proportions in some of them. These infections can give rise to a considerable number of complications, many with very serious consequences. Given that, in addition, a great number of cases are asymptomatic, a general consensus exists about the convenience of carrying out screening programmes. The aim of this study is to accomplish the first stage of the screening programme of asymptomatic infection by C. trachomatis in women who seek help at a family planning centre. METHODS: A descriptive study to determine the prevalence each year of the period studied, an analysis of its temporal tendency and the assessment of the programme effectiveness in terms of a proportional reduction in prevalence. A total number of 6.746 women were included, who attended the family planning centre for a regular checkup or contraceptive advice between January 1991 and December 1993. RESULTS: The programme showed a global effectiveness rate of 80%, with a reduction in prevalence from 5.1% in 1990 to 1.0% in 1993. A significant fall was observed in all the categories analyzed, except for women using prophylactics and those with higher education. CONCLUSIONS: The programme achieves its objectives very effectively. Nevertheless, it would be advisable to evaluate its efficiency together with a cost-analysis, since by reducing prevalence, the positive estimated value of the test considerably decreases, which raises the cost of a single case detection.

Adolescent↗
PubMed1984

Role of disulfide bonding in outer membrane structure and permeability in Chlamydia trachomatis.

The outer membrane of Chlamydia trachomatis can be efficiently solubilized by a variety of mild detergents in the presence of the reducing agent dithiothreitol. This allows purification of the chlamydial major outer membrane protein at high yield in very gentle conditions by using its differential solubility in Sarkosyl and octylglucoside in the presence of dithiothreitol. The major outer membrane protein of the L2 serovar is an acidic protein with a pI of ca. 5. It contains three cysteine residues that allow it to form a disulfide-linked proteinaceous network responsible for the characteristic rigid outer membrane of the elementary body. By the use of an in vitro reconstitution assay developed by Nikaido and his co-workers, it was shown that the outer membrane contains pores with an "exclusion limit" between molecular weights 850 and 2,250. In addition, the "opening-closing" of the pores was shown to be controlled through a simple reduction-oxidation mechanism. A model that outlines the role of disulfide bonding in the physiology of chlamydial development is presented.

Amino Acids↗
PubMed1993

Characterization of glycoproteins from Chlamydia trachomatis using lectins.

Glycoproteins in Chlamydia trachomatis, serotype L1, elementary bodies were studied by lectin blotting. A panel of 23 lectins representing a variety of sugar specificities was used. The pattern of lectin-binding specificities at a peptide band was studied in order to determine the type and structure of its glycoconjugate. To establish chlamydial origin of the glycopeptide bands in the blot, control samples from non-infected host cell membranes were run in parallel. Terminal mannosidic structures were demonstrated in a 72 kDa glycopeptide (gp72) by its selective binding of Galanthus nivalis lectin (GNA). Sialic acids were found in two chlamydial glycopeptides, gp40 and gp64, which appear to carry O-linked glycoconjugates as they bound the peanut agglutinin (PNA, both gp40 and gp64) and jackfruit lectin (Jac, only gp40). Such structures were also present in other chlamydial glycopeptides. Lectins with specificities for fucose in different links, galactose and N-acetyl glucosamine bound to several chlamydial peptides. On the basis of our results we suggest an alternative mechanism for uptake of chlamydial elementary bodies into host cells, namely phagocytosis mediated by eukaryotic cell surface lectins.

Bacterial Proteins↗
PubMed2000

Evidence for long-term cervical persistence of Chlamydia trachomatis by omp1 genotyping.

Recurrent Chlamydia trachomatis infections are common among sexually active women. Although recurrences with a new chlamydial serovar indicate reinfection, same-serovar recurrences may be due to persistence. Because persistence has important implications for pathogenesis and patient management, we identified 552 women with >3 recurrences over 2 years. Among these, 130 women (24%) had same-serovar recurrences; 58 (45%) were C class serovars (odds ratio, 2.4; 95% confidence interval, 1.7-3.5; P<.0001). Forty-five isolates from 7 women with 3-10 repeated, same-serovar infections over 2-5 years were studied. As determined by omp1 genotyping, 4 women had identical genotypes at each recurrence; 2 women had 1 or 2 amino acid changes following treatment, and one was persistently infected with a unique genotype, Ja. Many intervening culture-negative samples were positive when tested by ligase chain reaction, which suggests persistence. These data demonstrate that cervical infections with C class serovars can persist for years and may have specific biologic properties that allow for modulation of the major outer membrane protein in response to immune selection.

Anti-Bacterial Agents↗
PubMed1980

Studies on the ultrastructure of envelope of elementary bodies of Chlamydia trachomatis.

Electron microscopy of purified Chlamydia trachomatis treated by various physical and chemical means shows that the envelope of the elementary bodies (EB) consists of the outer cell wall layer, the inner cell wall layer, and the inner membrane. The outer cell wall layer is mainly made up of granular subunits arranged in a hexagonal pattern and may be called the "mural structural protein layer". It forms together with the inner cell wall layer the rigid cell wall. The inner or protoplasmic membrane is not easily shown in the young EB. In the negatively stained specimen, a frail and easily removable superficial layer is seen adhering to the "mural structural protein layer". But in ultra-thin sections this superficial layer is not shown separately. There are fold-like grooves which are special structures probably related to reproduction. There are seen some EB's in binary fission, and a number of bodies very big in size yet having morphological characteristics of the EB's, which are in various processes of multiplication, such as binary fission, budding, and "multicentered germination". These observations give a challenge to the current opinion that only the initial bodies have the power of reproduction.

Cell Membrane↗
PubMedDate not supplied

The prevalence of Chlamydia trachomatis in young women.

BACKGROUND: Chlamydia trachomatis infection is common in women with pelvic inflammatory disease, infertility and ectopic gestation. In this study we examined the prevalence of this infection in young women undergoing routine gynaecological checks. METHODS: Three hundred and five women aged between 19 and 41 were included in our study. Endocervical smears were collected by speculum examination, air-dried, acetone-fixed and stained for chlamydial antigen using fluorescein-labelled monoclonal antibody. RESULTS: Ninety-five per cent of the women were asymptomatic. Only 5% had mild symptoms such as white discharge, abdominal pain or profuse periods; 34% gave a history of white discharge only. Chlamydial antigen was detected in cervical smears from 47 (15%) women. Of these, 9 (19%) had symptoms at examination and 20 (43%) had symptoms within 2 months. On gynaecological examination 25 women (53%) had minor signs such as erosion or cervicitis and only 1 (2%) had uterine tenderness suggestive of mild pelvic inflammatory disease. CONCLUSIONS: It is important to diagnose chlamydial infection early because in its later stages it is associated with an ascending infection and serious complications. Young, relatively asymptomatic women should be screened for the presence of this organism.

Adult↗
PubMedDate not supplied

The effect of orientation within a chimeric peptide on the immunogenicity of Chlamydia trachomatis epitopes.

Peptides representing the Chlamydia trachomatis major outer membrane protein variable domains (VD) 1 and 4 of serovars C and E, respectively, have been shown to elicit a neutralizing antibody response in mice. To assess whether the position within a chimeric peptide influences the immunogenicity of the epitopes, two constructs, VD 1-4 and VD 4-1, were made in which the position of the VD relative to the amino and carboxy terminals were rotated. C57BL/10 mice were immunized with 100 micrograms of peptide in complete Freund's adjuvant (FA) on day 0, followed by an immunization with peptide (100 micrograms) in complete FA on day 14. By day 21 the immunodominant epitope in both chimeras as measured by ELISA was the one located at the carboxy terminus. A pepscan of the VD 1-4 antisera revealed a main peak in VD 4 which had been previously identified by neutralizing MAbs. The VD 4-1 antisera gave a peak in the VD 1 region which did not correspond to regions previously mapped with neutralizing MAbs. The VD 1-4 antisera but not the VD 4-1 antisera was able to neutralize in vitro serovar E. In summary, the position of these chlamydial epitopes within a chimeric peptide greatly influenced the resulting immune response.

Amino Acid Sequence↗
PubMed1985

Infection with Chlamydia trachomatis in female college students.

Chlamydia trachomatis was isolated from genital specimens from 21 (4.9%) of 431 female college students. Antibody to C. trachomatis was found in the genital secretions of 52 (11.9%) of 437 women. Multiple logistic regression analysis showed race, number of sexual partners, and use of barrier methods of contraception to be predictive of infection with C. trachomatis. Logistic regression analysis found race, number of sexual partners, use of barrier methods of contraception, and presence of cervical erythema to be predictive of local chlamydial antibody. White participants were infected less often (12 of 388 (3.1%)) than black participants (9 of 43 (20.9%)) (p less than 0.001) and were less likely to have local chlamydial antibody. None of the sexually inexperienced women were infected or had local antibody. Among the sexually experienced women, chlamydial infection and local chlamydial antibody increased with increasing number of sexual partners only for women who were not using barrier methods of contraception. Sexually experienced women who used barrier methods of contraception (condom, diaphragm) were less likely to be infected (one of 105 (1.0%)) than were sexually experienced women who used other contraceptive measures or who did not use contraception (20 of 276 (7.2%)) (p = 0.031). Women who used barrier methods of contraception also were less likely to have local chlamydial antibody. Women with cervical erythema were more likely to have local chlamydial antibody (4 of 11 (36.4%)) than women without cervical erythema (48 of 426 (11.3%)). Vaginal colonization with other sexually transmitted microorganisms (Mycoplasma hominis, Ureaplasma urealyticum, Trichomonas vaginalis) was noted more often among women with chlamydial infection than among uninfected women.

Adult↗
PubMed2002

Cervicovaginal coinfections with human papillomavirus and Chlamydia trachomatis.

Human papillomavirus (HPV) and Chlamydia trachomatis (CT) are the two most common sexually transmitted pathogens, and infection with either reportedly was associated with cervical intraepithelial neoplasia (CIN) in women. In view of their similar mode of transmission, CT infection was examined as a possible HPV cofactor in the etiology of CIN disease. In total, 129 women were included in the study, of whom 80 were negative (mean age 34.17 +/- 6.9) and 49 were positive (mean age 33.16 +/- 6.8) for HPV DNA (assessed by PCR). CT DNA was determined in endocervical and first-catch urine specimens by PCR. Whereas HPV-positive and HPV-negative women were similar with respect to age (p = 0.419) and pregnancy outcomes (p = 0.628), the number of smokers (p = 0.001), women with multiple male sex partners (p = 0.002) or with abnormal cytology (p < 0.001) was higher in the HPV-positive group. There was an increase in CT infection rate in HPV-positive (29/49) as compared to HPV-negative (10/80) women (p < 0.01). Within HPV-positive patients, there was no significant difference between CT-positive and CT-negative patients with regards to the risk factors studied. Collectively, this suggests that CT infection is a cofactor of HPV in CIN disease development, possibly by modulating the host's immunity and/or precipitation of chronic inflammation.

Adult↗
PubMed2005

Comparative genomic analysis of Chlamydia trachomatis oculotropic and genitotropic strains.

Chlamydia trachomatis infection is an important cause of preventable blindness and sexually transmitted disease (STD) in humans. C. trachomatis exists as multiple serovariants that exhibit distinct organotropism for the eye or urogenital tract. We previously reported tissue-tropic correlations with the presence or absence of a functional tryptophan synthase and a putative GTPase-inactivating domain of the chlamydial toxin gene. This suggested that these genes may be the primary factors responsible for chlamydial disease organotropism. To test this hypothesis, the genome of an oculotropic trachoma isolate (A/HAR-13) was sequenced and compared to the genome of a genitotropic (D/UW-3) isolate. Remarkably, the genomes share 99.6% identity, supporting the conclusion that a functional tryptophan synthase enzyme and toxin might be the principal virulence factors underlying disease organotropism. Tarp (translocated actin-recruiting phosphoprotein) was identified to have variable numbers of repeat units within the N and C portions of the protein. A correlation exists between lymphogranuloma venereum serovars and the number of N-terminal repeats. Single-nucleotide polymorphism (SNP) analysis between the two genomes highlighted the minimal genetic variation. A disproportionate number of SNPs were observed within some members of the polymorphic membrane protein (pmp) autotransporter gene family that corresponded to predicted T-cell epitopes that bind HLA class I and II alleles. These results implicate Pmps as novel immune targets, which could advance future chlamydial vaccine strategies. Lastly, a novel target for PCR diagnostics was discovered that can discriminate between ocular and genital strains. This discovery will enhance epidemiological investigations in nations where both trachoma and chlamydial STD are endemic.

Amino Acid Sequence↗
PubMed1992

Comparison of two culture approaches, blind passage and dual observation, for detecting Chlamydia trachomatis in various prevalence populations.

Chlamydia trachomatis diagnosis in our laboratory consisted of dual inoculation of shell vials and detection of inclusions by using fluorescein-conjugated monoclonal antiserum; the second culture vial was conventionally used for blind passage when the first vial was negative. We compared the increase in positivity using blind passage with that of a strategy utilizing observation of two stained monolayers (dual observation) without blind passage, in an effort to reduce the reporting time and labor associated with the conventional approach. A total of 4,329 specimens were obtained from an obstetrics and gynecology (OB-GYN) clinic (2,563 specimens) and the sexually transmitted disease clinic (1,766 specimens). These specimens were used to compare the two strategies. Blind passage of 1,269 initially culture-negative specimens from the OB-GYN clinic resulted in an additional 6 positive chlamydial diagnoses. In comparison, a similar number of specimens (1,294) from the OB-GYN clinic collected subsequently to the first group were tested by dual observation. There were five additional positive findings. A similar evaluation of specimens from the sexually transmitted disease clinic was performed. Blind passage of 313 initially culture-negative specimens yielded 3 additional positive diagnoses, whereas dual observation of 1,435 similar specimens resulted in 9 positive diagnoses. On the basis of analysis of 4,332 specimens, sensitivity of dual observation is comparable to that of blind passage; labor, cost, and reporting time of dual observation are reduced in comparison to those of blind passage.

Bacteriological Techniques↗