Sexually Transmitted Infections: Symptoms, Causes, and Treatment
Nongonococcal Urethritis (NGU)
Definition:
Nongonococcal urethritis (NGU) is an inflammation of the urethra caused by infections other than Neisseria gonorrhoeae. It is a common condition in sexually active individuals and a leading cause of urethritis.
Etiology:
The most common causes of NGU include:
- Chlamydia trachomatis – The primary causative agent.
- Mycoplasma genitalium – Often linked to recurrent or resistant cases.
- Ureaplasma urealyticum – Found in the urogenital tract.
- Herpes Simplex Virus (HSV) – In some cases.
- Trichomonas vaginalis – A less common protozoan cause.
Clinical Features:
- Urethral discharge: Typically clear or white.
- Dysuria: Painful urination.
- Itching or irritation at the urethral opening.
- Mild pelvic pain or discomfort.
- Asymptomatic cases: Some individuals may not show symptoms but can still transmit the infection.
Pathogenesis:
NGU is primarily transmitted through sexual contact. The infection causes inflammation of the urethra.
Chlamydia trachomatis infects epithelial cells of the urethra, leading to intracellular infection and inducing an inflammatory response. It often leads to chronic urethritis, which can become asymptomatic in some individuals.
Mycoplasma genitalium and Ureaplasma urealyticum also infect the urethra but are known for causing more persistent and sometimes recurrent infections due to their ability to evade the immune system and form biofilms.
HSV can cause painful ulcerations in the urethra, leading to viral urethritis.
Trichomonas vaginalis causes irritation and inflammation in the urethra but is less common in men.
Diagnosis:
- PCR tests to identify the causative organism.
- Urethral swab culture or urine tests.
- Gram stain may show white blood cells, but no organisms.
Significant Bacteriuria / Asymptomatic Bacteriuria
Definition:
Significant bacteriuria refers to the presence of a high concentration of bacteria in the urine (typically >105 CFU/mL) with accompanying symptoms such as dysuria, urgency, and frequency, indicating a urinary tract infection (UTI).
Asymptomatic bacteriuria (ASB) is the presence of bacteria in the urine without any clinical symptoms of UTI. ASB is common in certain populations but does not require treatment unless specific conditions exist.
Etiology:
- Escherichia coli (most frequent)
- Klebsiella pneumoniae
- Enterococcus faecalis
- Proteus spp.
- Pseudomonas aeruginosa
- Enterobacter spp.
Pathogenesis:
Asymptomatic Bacteriuria (ASB): In ASB, bacteria colonize the urinary tract, particularly the bladder, without triggering the body’s immune response or causing symptoms. Factors like host immune tolerance, normal microbiota, and bladder pH may contribute to this absence of symptoms.
Significant Bacteriuria: In contrast, significant bacteriuria leads to an inflammatory response in the urinary tract. The infection typically ascends from the urethra to the bladder, causing irritation and symptoms such as pain, burning during urination, and increased frequency.
Risk factors for significant bacteriuria include female sex (shorter urethra), diabetes, urinary tract abnormalities, pregnancy, and instrumentation such as catheterization.
Diagnosis:
Urine Culture: A urine culture with >105 CFU/mL confirms significant bacteriuria.
For ASB: ASB is diagnosed if the urine contains >105 CFU/mL of bacteria in a patient without UTI symptoms.
Microscopy: Pyuria (white blood cells in the urine) may indicate infection, but the absence of pyuria does not rule out ASB.
Treatment:
ASB: Treatment is generally not recommended unless in pregnant women, those undergoing urological procedures, or individuals with other risk factors like diabetes.
Significant Bacteriuria: Requires appropriate antibiotic treatment (e.g., nitrofurantoin, TMP-SMX, or ciprofloxacin) based on urine culture sensitivity.
Complications:
For ASB: In untreated pregnant women, ASB can lead to preterm labor or low birth weight.
For Significant Bacteriuria: If untreated, significant bacteriuria can progress to pyelonephritis, sepsis, or chronic kidney disease.
Lymphogranuloma Venereum (LGV)
Definition:
Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by specific serovars (L1, L2, L3) of Chlamydia trachomatis. It predominantly affects the lymphatic system and is characterized by genital ulcers, painful lymphadenopathy (swelling of lymph nodes), and systemic symptoms like fever.
Etiology:
- Causative agent: Chlamydia trachomatis serovars L1, L2, and L3.
- The infection is primarily transmitted through unprotected sexual contact, including vaginal, anal, and oral routes. It often affects individuals with multiple sexual partners.
Pathogenesis:
The infection begins at the mucosal site (genital or rectal), where Chlamydia replicates within host cells, forming intracellular inclusions.
The bacteria spread through lymphatic vessels to regional lymph nodes, causing swelling, inflammation, and the formation of painful, tender buboes.
Without proper treatment, the infection can progress, causing chronic inflammation and scarring in the genital or rectal areas, leading to strictures or other complications.
In women, the infection may spread to the pelvic organs, resulting in pelvic inflammatory disease (PID).
Clinical Features:
Primary Stage: A small, painless genital ulcer or papule at the site of infection, which may resolve without notice.
Secondary Stage: Enlargement and pain in the inguinal or femoral lymph nodes (buboes), fever, chills, and malaise. Women may experience pelvic pain, discharge, or rectal discomfort.
Tertiary Stage: Chronic infection can lead to scarring, rectal or genital strictures, and proctitis.
Diagnosis:
- Nucleic Acid Amplification Tests (NAAT) are the most sensitive method for detecting Chlamydia.
- Serology: Detection of LGV-specific antibodies.
- Swab cultures can confirm the presence of the organism.
Treatment:
- Doxycycline (100 mg twice daily for 21 days) is the standard treatment.
- Azithromycin (1 g orally, once a week for 3 weeks) is an alternative.
Complications:
Chronic LGV can result in severe complications like genital or rectal strictures, proctitis, and fibrosis.
Vulvovaginitis
Definition:
Vulvovaginitis is inflammation or infection of the vulva and vagina, characterized by itching, redness, swelling, abnormal discharge, and discomfort. It is common among women of all ages and can be caused by both infectious and non-infectious factors.
Etiology:
- Infectious causes:
- Bacterial vaginosis (BV): Caused by an overgrowth of Gardnerella vaginalis and other anaerobic bacteria, disrupting the vaginal flora.
- Candidiasis: Candida albicans, a yeast, causes fungal infections in the vagina.
- Trichomoniasis: Caused by Trichomonas vaginalis, resulting in a frothy discharge.
- STIs: Chlamydia trachomatis, Neisseria gonorrhoeae, and Herpes simplex virus (HSV) can also cause vulvovaginitis.
- Non-infectious causes:
- Allergic reactions: Sensitivity to soaps, detergents, or fabrics can irritate the vulvovaginal area.
- Hormonal changes: Estrogen fluctuations, such as during menopause, may lead to dryness and inflammation.
- Physical irritants: Tight clothing or poor hygiene may also contribute to irritation.
Clinical Features:
- Itching and burning sensations.
- Abnormal discharge: White, cottage cheese-like (in candidiasis) or watery, foul-smelling (in BV).
- Redness and swelling of the vulva.
- Painful urination or intercourse.
Diagnosis:
- Clinical examination: Based on symptoms and history.
- Microscopy: Wet mount or Gram stain of vaginal discharge to identify pathogens.
- Culture and PCR: Used to detect specific STIs like Chlamydia or Trichomonas.
Treatment:
- Antifungals for candidiasis (e.g., Fluconazole).
- Metronidazole or Clindamycin for BV.
- Tinidazole for trichomoniasis.
- Topical corticosteroids for allergic causes.
Complications:
Untreated vulvovaginitis may lead to recurrent infections, pelvic inflammatory disease (PID), or complications during pregnancy.
Donovanosis (Granuloma Inguinale)
Definition:
Donovanosis, also known as granuloma inguinale, is a rare, chronic, sexually transmitted bacterial infection caused by Klebsiella granulomatis. It is characterized by painless, progressive genital ulcers and granulomatous tissue growth.
Etiology:
- Causative agent: Klebsiella granulomatis (formerly known as Calymmatobacterium granulomatis).
- It is transmitted through sexual contact, but non-sexual transmission is rare.
Clinical Features:
- Primary lesion: Small, painless papule or nodule at the site of infection (genitals, perineum, or rectum).
- Ulceration: The lesion progressively ulcerates, forming beefy-red, well-vascularized ulcers with raised, rolled edges.
- Granulomatous tissue: The ulcers often develop into granulomatous tissue with a characteristic “fleshy” appearance.
- Location: Commonly affects the genital area but can also involve the inguinal area, rectum, or other mucosal surfaces.
- Lymphadenopathy: Rarely, regional lymph nodes may be involved.
Diagnosis:
- Microscopy: Presence of Donovan bodies (intracellular inclusions) in the cytoplasm of macrophages in tissue samples or smear preparations.
- PCR: Nucleic acid amplification tests (NAAT) can be used to detect Klebsiella granulomatis.
- Culture: It can be difficult to culture, but a culture can help in confirming the diagnosis.
Treatment:
- Antibiotics: The first-line treatment is Doxycycline (100 mg twice daily for 3 weeks or until lesions resolve).
- Alternatives: Azithromycin (1 g weekly), Ciprofloxacin, or Erythromycin are used in cases where doxycycline is contraindicated or ineffective.
Complications:
If untreated, Donovanosis can lead to extensive tissue damage, scarring, and, in rare cases, penile or vaginal deformities.
There is also an increased risk of secondary bacterial infections.
VDRL / RPR Test
Definition:
The VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) tests are serological tests used to screen for syphilis, caused by the bacterium Treponema pallidum. Both tests detect non-treponemal antibodies, which are produced in response to lipids released from damaged cells during syphilis infection.
Etiology:
The tests detect antibodies against cardiolipin, a lipid present in the cell membranes, that react with reagin antibodies produced due to Treponema pallidum infection.
Principle:
VDRL and RPR tests are based on a flocculation reaction, where patient serum is mixed with cardiolipin antigen. The presence of antibodies causes the antigen to form visible clumps (flocculation).
RPR is a more rapid version of the VDRL test, using a carbon particle antigen, making it easier to visualize the reaction.
Clinical Use:
- Screening: Both tests are used as initial screening tools for syphilis. A positive result indicates possible syphilis infection, but further testing is required to confirm the diagnosis.
- Monitoring treatment: These tests are useful in assessing treatment efficacy and detecting treatment failure or relapse, as antibody titers should decrease with effective therapy.
Limitations:
- False positives: Can occur in diseases like malaria, lupus, pregnancy, or autoimmune diseases, leading to a need for confirmation with more specific tests like FTA-ABS (Fluorescent Treponemal Antibody Absorption) or TPHA (Treponema pallidum Hemagglutination Assay).
- False negatives: May occur in early or late stages of syphilis, where the immune response is insufficient.
Treatment:
Penicillin remains the treatment of choice for syphilis, regardless of the stage.
Chancroid
Definition:
Chancroid is a highly contagious, sexually transmitted bacterial infection caused by Haemophilus ducreyi. It is characterized by the development of painful genital ulcers with soft, irregular borders and often associated with inguinal lymphadenopathy.
Etiology:
- Causative agent: Haemophilus ducreyi, a gram-negative bacillus.
- Transmitted through sexual contact, primarily affecting the genital area, but it can also involve the anus and mouth.
Clinical Features:
- Genital Ulcers: The primary lesion starts as a painful, red papule that progresses to a soft, ragged ulcer with a necrotic base and purulent exudate. These ulcers are typically deep, with soft, undermined edges.
- Painful Lymphadenopathy: Inguinal lymphadenopathy is common, with swollen, tender lymph nodes that may abscess and rupture, draining pus.
- Asymptomatic cases: Some individuals may remain asymptomatic but still carry and transmit the infection.
Diagnosis:
- Clinical Examination: Characteristic painful ulcers with soft, irregular edges and associated lymphadenopathy help diagnose chancroid.
- Gram Stain: Direct smear from an ulcer shows gram-negative bacilli in “school of fish” or “railroad track” arrangement.
- Culture: Culturing Haemophilus ducreyi from the ulcer may confirm the diagnosis but is often difficult due to the fastidious nature of the bacteria.
- PCR: Nucleic acid amplification tests (NAAT) can be used for definitive diagnosis.
Treatment:
- Antibiotics: The first-line treatment includes Azithromycin (1 g single dose), Ceftriaxone (250 mg IM), or Erythromycin (500 mg four times daily for 7 days).
- Management of Lymphadenopathy: Drainage of abscessed lymph nodes may be necessary.
Complications:
If untreated, chancroid can lead to scarring, chronic ulcers, and an increased risk of HIV transmission.