Men's Health Education: Understanding the Causes, Symptoms, and Treatment of Non-gonococcal Urethritis (NGU)

Nongonococcal Urethritis (NGU)

(I) Overview

Urethritis caused by pathogens other than gonococcus is called nongonococcal urethritis. Its incidence is 1 to 4 times that of gonorrhea. The main pathogens causing nongonococcal urethritis are Chlamydia and Mycoplasma. Chlamydia trachomatis, which causes urethritis, is a highly infectious bacterium, mostly transmitted through sexual activity, and is difficult for the human body to eradicate. Approximately 10% to 20% of humans are infected, but infection can remain asymptomatic for a long period. Chlamydia parasitizes human cells and cannot grow on cell-free culture media, nor can it reproduce extracellularly, requiring energy from the host cell. Chlamydia possesses both DNA and RNA, is sensitive to antibiotics, and has complex metabolic functions; therefore, it is generally considered to be a bacterium.

Chlamydia primarily infects the columnar epithelial cells of the superficial layer of the human urethra, without penetrating the lamina propria of the mucosa. Submucosal infiltration is limited to lymphocytes, and submucosal lesions persist even after antibiotic treatment. Following chlamydia infection, IgG, IgM, and IgA antibodies increase, but this effect is short-lived. Approximately 30% of gonorrhea patients develop urethritis symptoms 1-2 weeks after being cured with penicillin; this is known as post-gonococcal urethritis. This is often caused by chlamydia infection, and it should be noted that these patients may also be reinfected with gonococci or have experienced treatment failure.

(II) Transmission and Epidemiology

Like gonorrhea, NGU is most common in sexually active young adults, with a peak incidence between 20 and 30 years of age, and 60% of cases occurring in individuals under 25. Since the 1960s, the incidence of NGU has risen sharply, surpassing gonorrhea to become the leading sexually transmitted disease in Europe and America. By the 1980s, the number of new cases in the United States alone reached 3 to 10 million annually, leading some to call it the "sexually transmitted disease of the 1980s."

(III) Clinical Manifestations

1. Typical clinical symptoms of NGU include urethral itching accompanied by mild to severe urinary urgency, dysuria, and difficulty urinating.

2. Before prolonged periods without urination or the first urination in the morning, a small amount of watery mucous discharge may leak from the urethral opening. Sometimes this only manifests as a suffocating urethra or soiling of the groin, easily washed away by the urine stream.

3. The incubation period for NGU is 1 to 3 weeks. Some patients may be asymptomatic. Due to the slow onset and atypical symptoms, approximately 50% of patients are missed at initial diagnosis. 4. During physical examination, in addition to observing the discharge, carefully examine the external genitalia for rashes, inguinal lymph nodes for swelling, anal and perineal discharge for discharge, and whether segmental induration or discharge from the urethra is felt upon palpation.

5. Gonorrhea and NGU are urethritis caused by two different pathogens. They can occur in the same patient at the same time, and due to their similar clinical symptoms, clinical differentiation is very important.

6. NGU patients may develop complications if not properly managed or treated promptly. Statistics show that about 1% of patients may develop complications, the most common being acute epididymitis, usually unilateral, with typical symptoms of urethritis and epididymitis coexisting. A very small number of patients may develop Reiter's syndrome (those with a genetic predisposition to HLA-B27 haplotype antigen may also present with urethritis, arthritis, keratitis, conjunctivitis, and rashes). Proctitis or pharyngitis may also be found in patients with homosexual or other abnormal sexual behaviors. In female patients, Bartholin's gland inflammation, vaginitis, cervicitis, pelvic inflammatory disease, ectopic pregnancy, or infertility are common. Newborns may develop conjunctivitis or even pneumonia when passing through an infected birth canal.

(IV) Diagnosis Patients with urethritis symptoms generally provide a medical history and cooperate with examinations, making diagnosis relatively straightforward.

1. For patients without clinical manifestations, urethritis should be confirmed first, followed by differentiation from gonorrhea.

2. If there is no obvious urethral discharge, the first morning urine or urine 2-3 hours after the last urination should be collected and centrifuged. If necessary, gently squeeze the urethra from the base of the penis towards the external urethral opening to obtain a sample of discharge for Gram staining to rule out gonorrhea. A preliminary diagnosis can be made when 10-15 polymorphonuclear leukocytes are visible per high-power field, with no Gram-negative diplococci.

3. If clinical presentation and staining results of secretion smears are inconclusive or contradictory, or if penicillin- or tetracycline-resistant pathogens are suspected clinically, tissue culture should be performed. The composition of the swab tip used for cell culture is crucial for specimen collection. Swabs used for collecting Chlamydia trachomatis and herpes simplex virus for cell culture inoculation should not be tipped with calcium alginate, as calcium alginate can directly bind to these pathogens, leading to culture failure. Instead, swabs with nylon, deltamethrin, carbonized cotton, or polyester tips can be used. Wooden swabs should not be placed in culture media used for transport, as the wooden stalks contain substances that inhibit gonococci, etc. (likely fatty acids).

(V) Treatment

Unlike gonorrhea, NGU symptoms do not usually disappear spontaneously after 2-3 months. Chlamydia pathogens can persist for several months and pose a risk of potential complications. If possible, the pathogen should be identified first for targeted treatment. In cases where equipment is insufficient for chlamydia testing, treatment often relies on experience and employs broad-spectrum antibiotics.

1. Tetracycline, doxycycline, or erythromycin are generally preferred, showing good efficacy against Chlamydia trachomatis (failure rate 20%). Extending the treatment course can reduce recurrence; some studies have shown that after one week of tetracycline use, the recurrence rate within 6 weeks after discontinuation is as high as 30%–40%. Doxycycline, 100mg twice daily for one week, is more convenient.

2. If gonorrhea is also present, penicillin should be used to treat the gonorrhea first, followed by doxycycline.

3. Penicillin is ineffective against NGU, while sulfonamides are effective against Chlamydia; conversely, streptomycin and spectinomycin have little effect on Chlamydia.

4. Spiramycin 200mg, three times daily, for 7–10 days.