| Abstract: |
SUMMARY AND CONCLUSIONChlamydiae are non motile obligatory intracellular parasites, have a unique developmental cycle. The genus Chlamydiae contain four species, Chlamydia trachomatis, Chlamydia psittaci, Chlamydia pneumoniae and Chlamydia pecorum.Chlamydia psittaci is zoonotic, causmg respiratory tract infections and psittacosis in human. While, C. pneumonia has established as a cause of community acquired pneumonia and IS associated with acute and chronic coronary heart disease.Chlamydia trachomatis is the most important species of this genus. Worldwide, C. trachomatis is a known cause of trachoma and it is one of the most common sexually transmitted bacterial infections. C. trachomatis has been incriminated as a cause of urethritis, cervicitis and premature labour in females. Many of these infections may remain asymptomatic, that is why these infections may remain undetected and untreated thus resulting in severe subsequent sequelae such as ectopic pregnancy and tubal infertility. In males, C. trachomatis is considered as a cause of urethritis and prostatitis. In addition, conjunctivitis and/ or pneumonia can develop in infants exposed to infection during their passage through a Chlamydia trachomatis infected birth canal.In an effort to prevent the spread of C. trachomatis infections and their serious reproductive sequelae associated with undetected infections, increased attention is being paid to early diagnosis and treatment. The diagnosis of C. trachomatis infection was based primarily on isolation of the organism in tissue culture which is the standard method for diagnosis of C. trachomatis infection but its sensitivity is less than 85% in most laboratories. It requires careful specimen collection and stringent transport conditions with maintenance of the cold chain. In addition, Culture also requires 48 to 72 hours to perform so it is time consun1ing. For this reasons, theperformance of tissue culture for the detection of Chlamydia trachomatis is generally limited to a small number of laboratories.So rapid, easily performed and accurate diagnostic tests would facilitate early recognition and treatment of the infected cases that reduce transmission of infection in the community. Nonculture tests for detection of C. trachomatis in clinical specimens, such as enzyme immunoassay (EIA), direct fluorescent antibody test (DFA) and nucleic acid hybridization, these tests did not require viable organisms, thus circumventing some of collection and transport problems associated with tissue culture.Direct fluorescent antibody test (DFA) was able to detect C. trachomatis using fluorescein conjugated monoclonal antibodies that react with the MOMP of the EBs and RBs. The anti-MOMP monoclonal antibodies are prepared against C. trachomatis and are species-specific, thus will not stain C. psittaci or C. pneumoniae and the quality of fluorescence is better because MOMP is evenly distributed on the chlamydial particle. DF A test is very sensitive and specific, it is more rapid and less expensive than culture and no special transport requirments are necessary.The introduction of nucleic acid an1plification has been the most important advance in the field of Chlamydia diagnostics. Nucleic acid amplification tests are highly sensitive and specific. The polymerase chain reaction (PCR) is the most nucleic acid amplification test widely used.This work was carried out to evaluate the polymerase chain reaction (PCR) as a sensitive diagnostic tool in detection of Chlamydia trachomatis endocervical infection.The present work was conducted in Microbiology &Immunology Department and Obstetric & Gynecology Department, Faculty of Medicine, Zagazig University. It included 40 females (patient group) attending the out patient clinic of Obstetric & GynecologyDepartment: 23 females with mucopurulent cervicitis and 17 females with tubal infertility (7 with primary infertility and 10 with secondary infertility) with ages ranged from 20 to 45 years, mean 29.87 years ± 7.04 SD. In addition to 20 apparently healthy fertile females (control group) attending a family planning clinic with ages ranged from 22 to 45 years, mean 31.2 ± 8.12. Both groups were matched in age.All subjects were subjected to full history taking and two endocervical samples were taken for diagnosis of Chlamydia trachomatis infections, one for the polymerase chain reaction (PCR) by using two sets of primer, one directed to the cryptic plasmid and the other to MOMP gene of Chlamydia trachomatis. The other sample for direct fluorescent antibody test (DFA).The results of this study showed that:1- The percentage of Chlamydia trachomatis endocervical infection was higher among the patient group (47.5%, 50.0% and 57.50/0 by DF A test, the MOMP-based PCR and the plasmid-based PCR, respectively) than amopg the control group (10.0% by the three tests) with significant diffrence between both groups.2- The percentage of C. trachomatis infection among patients with mucopurulent cervicitis was (34.7%, 43.3% and 52.1 % by DFA test, the MOMP-based PCR and the plasmid-based PCR, respectively). Among females used intrauterine device (IUD), the percentage of infection was higher (62.5% by DFA test and 87.5% by both PCRs) than among females did not use contraceptive method (12.5% by the three tests) with significant difference between both groups. While, the percentage of C. trachomatis infection among females used hormonal contraception was 28.5% by both DFA test and the MOMP-based PCR and 57.1 % by the plasmid-based PCR. But the difference between this group of females and the females who did not use contraceptive method is not significant3- The percentage of C. trachomatis infection among infertile females was 64.7% by both DFA test and the plasmid-based PCR and 58.8% by MOMP-based PCR with higher percentage among the females with secondary infertility (70.0% by both DFA test and the plasmid-based PCR and 60.0% by the MOMP-based PCR) compared with females with primary infertility (57.1 % by the three tests). However, the difference between both groups did not reach significance.4- The percentage of C. trachomatis infection was significantly higher among young aged females (20-30 years) (73.30/0 by the DFA test and 80.0% by both PCRs) than among the older aged females (>40 years) (20.0 % by both DFA test and the plasrnidbased PCR and 10.0% by the MOMP-based PCR).5- After resolution of discrepant results, The direct fluoresent antibody test (DFA) had sensitivity, specificity, positive and negative predictive values and accuracy of 87.5%, 100.0%, 100.0%,92.3% and 95.0%, respectively.6- The plasmid-based PCR had sensitivity, specificity, positive and negative predictive values and accuracy of 100.0%, 97.20/0, 96.0%, 100.0% and 98.30/0, respectively.7- The MOMP-based PCR had sensitivity, specificity, positive and negative predictive values and accuracy of 91.7%, 100.0%, 100.0%,94.7%,96.6%, respectively.In conclusion, C. trachomatis infection was prevalent among symptomatic and asymptomatic Egyptian females. There is a close association of C. trachomatis infection with the occurrence of tubal infertility which highlights the significant role of C. trachomatis as an aetiological agent for infertility.Based on sensitivity and specificity, our results indicate that PCR and DF A are the recommended methods for C. trachomatisdetection. It IS imperative to indicate that DFA shows lower sensitivity.Molecular detection of C. trachomatis usmg PCR in endocervical speCImens provided the best sensitivity and specificity. Therefore It IS concluded that the PCR technique is the method of choice for efficient and sensitive diagnosis of C. trachomatis.The polymerase chain reaction not only improve the sensitivity of detection of Chlamydia trachomatis in individual patients dramatically but also will change all the available data.As the plasmid-based PCR had higher sensitivity than MOMPbased PCR, the PCR with primer directed against the cryptic plasmid is the best candidate for use in detection of C. trachomatis in cervical smears.
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