I. Concept
Non-gonococcal urethritis (NGU), also known as non-gonococcal genitourinary tract infection, is a sexually transmitted disease transmitted through sexual contact with clinical manifestations of urethritis, but gonococcal infection cannot be detected in urethral secretions. The female patient has not only urethral inflammation, but also cervicitis and other inflammatory diseases of the genital tract, therefore, it is not precise enough to call it only urethritis, but it is called non specific genital infection (NSGI).
Epidemiology and high-risk factors
Let us first look at a set of figures.
In 2003, 730,450 cases of 7 types of STDs were reported in 31 provinces and cities.
Composition ratio of 7 kinds of STD in China in 2003
STD name
NGU
Gonorrhea
Acute
Condyloma
Syphilis
Genital Herpes
Soft chancre
LGV
Total
Number of cases
255863
213208
154922
72553
32755
765
384
730450
Composition ratio (%)
35.03
29.19
21.21
9.93
4.48
0.10
0.05
100.00
NGU and its complications, such as infertility, epididymitis and pelvic inflammatory disease, pose a serious threat to health, and also play a significant role in promoting the transmission of HIV infection. The role of NGU and its complications, such as infertility, epididymitis, and pelvic inflammatory disease, pose a serious health risk and are notable for their role in facilitating the transmission of HIV infection.
NGU is the most common sexually transmitted disease in the United States, with approximately 250,000 to 300,000 new cases each year. The prevalence of NGU infection in urban areas of the United Kingdom ranges from 2.6% to 12% in general practice and 28% in termination of pregnancy clinics. In the United States, the prevalence rate is 5% in the general population and 20% in the core population.
(i) Age
In the sexually active population, the younger the age, the greater the risk of NGU infection. Hiltunen Back et al. investigated 3686 patients with NGU, and the prevalence was highest in the age group of 15-19 years, with 16% in women and 14% in men. The risk factors for recurrence of NGU were evaluated in a retrospective cohort design and age was found to be the most important factor. The risk of recurrence increased 8-fold in women younger than 15 years, 5-fold in women 15-19 years, and 2-fold in women 20-25 years compared with the age group 30-44 years.
(B) Gender
The rate of CT infection was higher in women than in men. In a survey conducted by Vuylsteke et al. among 2784 female secondary school students studied in Belgium (mean age 17 years), the mean age at first intercourse was 16 years, 52% reported having had at least one sexual intercourse, and the proportion of unplanned pregnancies was quite high, proving that they did not The average age at first intercourse was 16 years, and 52% of the students reported having had at least one sexual intercourse, with a fairly high proportion of unplanned pregnancies, demonstrating a lack of safe contraception. The prevalence of NGU among sexually active women was 1.4%. Younger women are more likely than older women to have delayed visits to the clinic and are therefore more likely to have complications of NGU infection such as pelvic inflammatory disease. Therefore, it is necessary to strengthen sexual health education for adolescents, especially for females.
(iii) Ethnicity
In a survey conducted among Coventry residents in the United Kingdom, the groups with the highest prevalence of NGU were black females aged 15-19 years and black males aged 20-24 years, and the results of univariate analysis showed that the most important risk factor for NGU in males was blackness, with a relative risk of 10.4 and P 5 positive.
③The urine sediment from the first urine in the morning or 3-4 hours between urination was diagnostic under 400x microscopy with an average of >15 polymorphonuclear leukocytes per field of view.
④10 in male patients is diagnostic (but trichomonas infection should be excluded).
At present, only polymorphonuclear leukocytes and exclusion of gonococcal infection are required for clinical laboratory diagnosis to make a preliminary diagnosis; pathogenic diagnosis should also detect chlamydia, mycoplasma and other pathogens causing NGU.
It should be differentiated from gonococcal urethritis and cervicitis.
Laboratory examination methods
(a) direct microscopic examination
1.Chlamydia trachomatis
Chlamydia trachomatis specimens can be examined directly by microscopy through smear staining. Chlamydia trachomatis can proliferate in sensitive cells and form inclusion bodies in the cells. Clinical specimens are stained with Kimsa or iodine, and if a certain number of characteristic inclusions are found (e.g., Kimsa staining, oil microscopy of Chlamydia inclusions characterized by intracellular purple or blue structures, while the surrounding cell paddles are gray and the nucleus is pink), then a diagnosis can be made, which is a simple and inexpensive diagnostic method.
This method is simple and easy to perform, but is only applicable to the examination of neonatal conjunctivitis scrapings and is not suitable for the diagnosis of Chlamydia trachomatis infection in the genitourinary tract, because in this case, its sensitivity and specificity are extremely low.
2. Mycoplasma
It has been reported that mycoplasma can be observed with the help of ultra-high magnification microscope (e.g., multimedia multi-functional THMI-UP ultra-high magnification microscope produced by Shanghai Fosun Co., Ltd, which can magnify up to 10,000 times), and then direct observation by selecting the dark field of phase contrast field according to the observation needs, and the swimming mycoplasma and mycoplasma inclusion bodies can be observed.
(B) Chlamydia trachomatis direct immunofluorescence method
Commercialized kits are available. Application of direct immunofluorescence test, is the specific chlamydia monoclonal antibody with fluorescein labeling later check the specimen with or without chlamydia, if the specimen has chlamydia antigen (inclusion or protozoa), then and antibody binding, under the fluorescence microscope, the positive can see bright apple green protozoa and initiator.
The result is positive when the number of protozoa particles in a smear is l0 or more. This method has a sensitivity of 70% to 90% and a specificity of 83% to 99% for the diagnosis of Chlamydia trachomatis infection. Therefore, some laboratories rank it and chlamydia culture as the expanded “gold standard” method.
The advantages are: rapid, inexpensive, easy to operate, easy storage and transport of specimens, specimens of Chlamydia trachomatis do not have to be alive or infectious. The disadvantages are poor sensitivity in a low infection rate population and subjective influence of the laboratory personnel. It is most appropriate for testing people with a high prevalence of Chlamydia trachomatis (e.g., STD outpatients). This method requires a high level of skill for the laboratory personnel because of the possibility of mistaking certain luminescent particles (leukocytes, epithelial cells, pigment granules), bacteria and yeasts for Chlamydia trachomatis (“artificial artifact”).
(C) enzyme-linked immunosorbent assay
1, Chlamydia trachomatis
Enzyme immunoassay for Chlamydia is an enzyme-labeled test that detects chlamydial antigens in the urogenital tract specimens of patients. Positive specimens finally make the liquid show a color reaction, the absorbance of which can be measured by the enzyme marker, so the results are judged more objectively. The sensitivity of this test is 60% to 90%, and the specificity is 92% to 97%. The sensitivity and specificity of this method for the diagnosis of Chlamydia trachomatis infection is comparable to that of the direct immunofluorescence method. When the test results are negative, Chlamydia trachomatis infection cannot be completely excluded, possibly due to insufficient numbers of Chlamydia trachomatis or improper specimen collection.
A significant advantage of this method is the high degree of automation, can simultaneously test a large number of specimens, the results of the judgment of objectivity. Its disadvantage is that a batch of tests need to do 5 controls (3 negative, 1 positive, 1 blank control), in order to save reagents, the specimens can be accumulated to do in batches. It is best suited to detect Chlamydia trachomatis in high prevalence populations, as is the direct immunofluorescence method. When applied in a low prevalence population, it is advisable to interpret the results with caution.
2, the identification test of mycoplasma
Enzyme-linked immunosorbent assay (ELISA) is highly sensitive; micro-immunofluorescence method (MIF) has the characteristics of rapid, indirect hemagglutination test (IHA) and metabolic inhibition test (MIT) is commonly used for mycoplasma antibody detection, specificity and sensitivity are high, can be used as an auxiliary diagnosis and epidemiological investigation.
(iv) Latex immunodiffusion test (Chlamydia trachomatis)
Clearview reagent for the detection of Chlamydia is a latex complex of Chlamydia monoclonal antibody adsorbed on filter paper, which is sandwiched between two plastic plates. If the specimen added contains chlamydial antigen, the antigen in the specimen binds to the monoclonal antibody bound to the latex, and the complex moves forward by capillary action, and a black line appears in the result window, and the specimen is positive. This method has a sensitivity of 87% and a specificity of 98.8% for the diagnosis of Chlamydia trachomatis infection in the female cervix.
The advantages of this method are: it is simple, convenient, rapid and especially suitable for grassroots units (no complex instrumentation is needed and results can usually be obtained within 30 minutes). The disadvantage is that a sufficient amount of Chlamydia trachomatis antigen is required in the specimen, and false negatives can occur when the antibody content is low, and thus the sensitivity is not sufficient. If the test is negative and the patient continues to have symptoms, a chlamydia culture should be done.
(E) culture method
1, Chlamydia trachomatis
Chlamydia is a specialized intracellular parasite that can only grow and proliferate in living cells. The specimen will be treated and inoculated on live cells cultured in the laboratory, if the specimen has Chlamydia, then the inclusion bodies of Chlamydia can appear in the cells after culture. The cells commonly used in the laboratory today are McCoy cells, HeLa 229 cells and BHK-21 cells.
To achieve success in culture, the material taken is critical. The material taken must contain live cells, so the cotton swab taken must be inserted into the columnar epithelial site, rotated and left for 20 seconds so that the swab can adsorb more cells; cell culture is the gold standard method for diagnosis and identification of Chlamydia trachomatis, with high sensitivity and specificity, and a sensitivity of 70% to 95% in experienced laboratories.
This method can be used as a confirmatory test and a post-treatment healing test. The disadvantage is that the operation is more complex and more time-consuming, expensive, requiring a certain amount of experimental equipment, but a large number of specimens can be processed at the same time to reduce costs.
2.The isolation and culture of Mycoplasma urealyticum
Mycoplasma urealyticum can grow in artificial medium containing urea, decomposing urea to produce ammonia, so that the medium becomes alkaline, therefore, when the liquid medium changes from yellow to red and the liquid is still clear, there may be mycoplasma growth. When examining, first stain with Dienes stain, then observe with low magnification, if you see “fried egg”-like colonies, the specimen is positive.
(F) serum antibody test
After human infection with Chlamydia and Mycoplasma, the corresponding antibodies are produced in the serum and urogenital secretions. The use of indirect hemagglutination test, complement binding test and other methods to check the corresponding antibodies can be used as a basis for disease diagnosis, and serum antibodies have a high background detection rate in people at high risk for sexually transmitted diseases.
However, serologic tests are of little value in diagnosing uncomplicated genitourinary tract infections, i.e., the diagnostic value of serologic tests is limited, and they are generally not good at distinguishing presenting infections from previous infections because: to date, no test has been fully applicable to all types of chlamydial infections. The collection of specimens in the acute phase is often missed because of the mild symptoms early in the infection. Since serum antibodies can persist for a long time, detection of antibodies in a single serum specimen only indicates previous infection with this organism, and only a 4-fold increase in serum antibodies in the recovery phase compared to the acute phase with clinical symptoms supports the current presence of chlamydial infection. However, serum antibody levels are significantly higher in lymphogranuloma venereum (LGV) and Chlamydia trachomatis epididymitis and tubal inflammation, and testing serum antibody levels can help in the diagnosis.
Chlamydia neonatorum pneumonia can also be diagnosed by serological methods to determine anti-chlamydial IgM antibodies, which have diagnostic value.
(VII) polymerase chain reaction (PCR)
1. Chlamydia trachomatis
This is a method of in vitro amplification of specific DNA fragments, which has a high sensitivity for the diagnosis of genitourinary Chlamydia trachomatis infection, and can also detect Chlamydia trachomatis infection in those with negative cell cultures. The specificity is also 99% to 100%. However, there are reports of false positive PCR due to “residual (carry over)” contamination or false negative PCR due to the presence of Taqase inhibiting substances in the specimen.
Clinically, PCR results should be analyzed in the context of medical history and treatment, and if necessary, repeated or another site should be used for the test.
Another in vitro nucleic acid amplification test, the ligase chain reaction (LCR), has also been used to detect Chlamydia trachomatis infection. the sensitivity and specificity of PCR can be 94.5% and 99.5%, respectively; positive expected values and negative expected values are 97.5% and 98.8%, respectively. both LCR and PCR methods can consistently amplify the amount of Chlamydia trachomatis DNA up to the level of three Chlamydia protozoa.
The LCR technique was used in 1993 to detect infection with Ct. The LCR technique requires two pairs of primers and the involvement of DNA polymerase and heat-stable DNA ligase in the reaction.
Advantages of the LCR technique:
①Sensitivity and specificity are higher than other methods;
The LCR technique can detect CtDNA in women’s cervical swabs, men’s urethral swabs, and morning urine specimens, and can detect Chlamydia in urine specimens in particular, which is a non-invasive and non-invasive diagnostic method that makes screening of asymptomatic people possible and easy to accept, especially for women;
③LCR technology has a shorter detection time;
The LCR technique also has some specimen inhibition, but the inhibition rate is significantly lower than that of PCR.
Although culture has been used as the gold standard for the diagnosis of Ct infection, even in experienced laboratories, the sensitivity of cell culture is only 40%-85%, which reduces its value in detecting Ct infection in low prevalence populations.
The LCR technique is highly sensitive and specific for the detection of various prevalent populations, especially for the detection of female urine specimens, so the LCR technique is expected to become the new gold standard.
2.Mycoplasma
The current molecular biology of mycoplasma is mainly the application of polymerase chain reaction (PCR) and DNA probe technology for diagnosis. The latter has been rarely carried out.
The PCR tests currently used in NGU diagnosis in China are not standardized, so it is necessary to inform patients and physicians about the significance and methods of using PCR correctly. The primers and reagents that are in use in China should be evaluated and the substandard reagents should be eliminated; the newly developed reagents should be tested on a large number of specimens before promoting their application. Due to the special nature of venereal disease, the current diagnostic standard of venereal disease should be carried out according to the “Diagnostic Standard of Venereal Disease” issued by the Department of Disease Control of the Ministry of Health, and the conclusion should be based on the comprehensive results of clinical and test.
VII. Treatment
Mycoplasma is a microorganism without cell wall structure, clinically treated with antibiotics that interfere with protein synthesis (such as tetracyclines, macrolides) and antibiotics that prevent replication (such as quinolones) these three types of antibiotics.
1. The commonly used western drugs for the treatment of incipient NGU cases are.
(1) Tetracycline: 0.5g each time, 4 times a day, for at least 7 days. Usually 2-3 weeks. Or tetracycline combination (synthesized from 3 types of tetracycline, each tablet contains 69mg of desmethyl tetracycline hydrochloride, 115.5mg of chlorotetracycline hydrochloride, 115.5mg of tetracycline hydrochloride) 1 to 2 tablets, taken orally, 2 times/day for 2 to 3 weeks.
(2) Doxycycline: 0.2g orally for the first time, 0.1g orally twice a day for 7-10 days.
(3) Azithromycin: 0.5g for the first time, 0.25g for each subsequent dose, once a day for 5 days. Or 1g, once in one dose.
(4) Mymanomycin (dimethylaminotetracycline): 0.1g each time, 2 times a day for 7-10 days.
(5) Erythromycin: 0.25g-0.5g per day orally 3-4 times per day for 7-10 days.
(6) Roxithromycin:0.3g per time, 1 time per day for 7 days. Or 0.15g per time, 2 times a day for 7 days.
(7) Erythromycin stearate: 0.5g each time, 4 times a day for 7 days.
(8) Erythromycin ethyl succinate: 0.8g each time, 4 times a day for 7 days.
(9) Oxytetracycline 250mg, 4 times a day for 7 days.
(10)Fluazinic acid (ofloxacin): 200mg-300mg orally, 2 times daily for 7-14 days.
(11) Fluazinic acid 200mg 3 times a day for 14 days.
(12) Ciprofloxacin 250-400mg twice a day for 7-14 days.
(13) Telit (an antimicrobial agent of the erythromycin class) for oral anti-inflammatory treatment.
(14) Spectinomycin: 2g for men and 4g for women once intramuscularly.
(15) Ciprofloxacin: 250-500mg orally twice a day. Can be injected intravenously.
(16) Telbivudine: 0.2g each time, 2 times a day for 7 days.
2. There is no effective therapy for recurrent or persistent NGU cases. Metronidazole 0.2g, single dose, plus erythromycin or erythromycin, 7 days therapy is recommended.
3. Doxycycline and ofloxacin are not allowed in pregnant women with NGU. Erythromycin or erythromycin, 7 days therapy is recommended; or azithromycin, one dose.
Should follow the principle of timely amount, rule of medication, according to different conditions to choose the appropriate antibiotic therapy. Mycoplasma has no cell wall, so β-lactams and vancomycin are completely insensitive. Sulfanilamide and rifampin are effective against Chlamydia, but not against mycoplasma. Gentamicin, neomycin, and polymyxin are ineffective against Chlamydia. Streptomycin and spectacularin are ineffective against Chlamydia and effective against mycoplasma. Pregnant women and children should not use tetracycline, doxycycline and quinolones, but erythromycin can be used. In case of dual infection with gonorrhea and non-gonococcal urethritis, treatment with penicillin and gonorrhea is used first. At present, there are many strains resistant to tetracycline, doxycycline and erythromycin. The new generation of synthetic antimicrobials quinolones, not only effective against Chlamydia and Mycoplasma, but also highly sensitive to gonococcus.
4.Prospects and problems of DNA vaccine
The use of DNA vaccines to stimulate the body to produce protective immunity to prevent infection is the ideal method to endogenously express the gene product of the pathogen in the host and induce the body to produce specific cell-mediated immunity and humoral-mediated immunity, thus allowing the host to gain resistance to the pathogen. Chlamydia DNA vaccines are therefore a promising research direction and prospect.
Research advances in the three main aspects of chlamydial DNA vaccine design have led to the following findings.
(i) Antigenic epitopes: major outer membrane protein (MOMP), chimeric peptides combining variable region IV of MOMP and Gp8, PorB, Cap1, etc.
②Vectors: plasmids, viruses, dendritic cells (DC).
(iii) Immune adjuvants include granulocyte-macrophage colony-stimulating factor (GM-CSF), CpG oligodeoxynucleotides, etc.
Eko et al. constructed a MOMP vaccine candidate, VCG-MOMP, using recombinant Vibrio cholerae ghosts (rVCG), which has strong adjuvant properties, as a vector, and induced increased local and systemic Th1 immune responses in the genital tract mucosa after inoculation of mice by intramuscular injection. Immune T cells isolated from immunized mice were able to partially transfer the protective effect to unimmunized mice.
Igietseme et al. constructed another MOMP vaccine candidate, MOMP-IS-COMs, using lipophilic immune response stimulatingcomplexes (ISCOMs) with adjuvant properties as carriers, and immunized BALB/c mice by intramuscular injection with The local Th1 immune response in the mucosa of the reproductive tract of BALB/c mice appeared rapidly and at high levels.
Urgent issues to be addressed by Chlamydia DNA vaccine.
①Animal models of CT reproductive tract infection need to be established to best reflect whether CT vaccine can prevent CT infection in the reproductive tract and eye.
②There are multiple serotypes of CT MOMP, and the protective immune response stimulated is also serotype-specific. Since DNA immunization can vaccinate multiple gene fragments at the same time, if multiple gene fragments of Chlamydia antigens are vaccinated together, a more durable and potent immunity may be generated.
It is still necessary to find immune adjuvants for Chlamydia trachomatis MOMP-DNA vaccine, and effective immune adjuvants will make the application of the vaccine more likely to become a reality.
VIII. Cure criteria and prognosis
(A) Cure criteria
1. Clinical symptoms disappear for more than 1 week, and there is no discharge from the urethra, or there are ≤4 white red cells/100x microscope in the discharge.
2, urine clarification, sediment microscopy negative.
3, fluorescent immunoassay urethra (cervical) specimens negative for chlamydia and mycoplasma (when available).
(II) Precautions
1, the diagnosis of NGU, should first pay attention to exclude gonorrhea, if it can not be ruled out, can be given ceftazidime 250mg once intramuscular injection or the use of drugs that are effective for both.
2, the treatment of NGU, generally Chlamydia trachomatis is easier to clear than mycoplasma, mycoplasma in mycoplasma is easier to eliminate mycoplasma solium.
3, male treatment is generally more effective than female.
4. It is generally believed that Trichomonas vaginalis is also the causative agent of NGU, which is not routinely examined in some clinical hospitals, and clinicians lack sufficient attention to the role of Trichomonas vaginalis in the pathogenesis of NGU. The positive rate of smear test has been reported abroad to be lower than culture method and PCR test, and the detection rate of Trichomonas vaginalis among male patients in STD clinics is 1.8%-47%. Therefore, when routine treatment for NGU is ineffective or when sexual partners have trichomonas infection, vaginal trichomonas examination should be done and metronidazole can be given empirically for diagnostic treatment if necessary.
5.Rifampicin is a broad-spectrum antibiotic, which also has an inhibitory effect on CT, and its MIC for CT is 0.0001μ g/ml (tissue culture). It has less drug resistance, can enter the cells, and has high concentration in the genitourinary tract, and its effect is better than tetracycline and doxycycline in the treatment of NGU.
(C) The symptoms still exist after treatment, consider the causes
1. Sexual partners not treated: is the most common cause. It has been reported that 30.6% of the sexual partners of Chlamydia trachomatis-positive patients are also positive for Chlamydia, and 34.29% of the asymptomatic sexual partners of Mycoplasma solium-positive patients are positive for Mycoplasma.
2. Combined prostatitis: The incidence of prostatitis was reported to be 74% in 1100 NGU patients with urinary tract symptoms
Chronic prostatitis may be the most difficult reason for treatment of recalcitrant NGU, the longer the course of the disease, the greater the chance of combined prostatitis, can do prostate massage fluid examination.
3, normal flora dysbiosis: mainly patients who repeatedly use large amounts or long-term broad-spectrum antibiotics, but also those with primary infections. When the STD pathogen test is negative, urethra, cervical secretions, prostate fluid polymorphonuclear leukocytes test positive, and in the urethra or vagina can be cultured dominant conditional pathogenic bacteria, should be considered normal flora dysbiosis.
4, non-bacterial prostatitis: is the most common in chronic prostatitis, its clinical symptoms and finger anal examination and segmental urine culture without the growth of pathogenic microorganisms, but the prostate fluid polymorphonuclear leukocyte examination positive, after excluding other types of prostatitis, can be diagnosed as non-bacterial prostatitis.
5. STD phobia: When the pathogen examination is negative, urethra, cervical secretion, prostate fluid polymorphonuclear leukocyte examination is negative, STD phobia is to be considered in patients with psychological defects and excessive non-STD complaints, after excluding STDs and their comorbidities. Psychological and suggestive treatment is mainly given, and if necessary, tricyclic antidepressants such as doxepin, amitriptyline or Valium and other psychotropic drugs are given.