Gonococcal Infections¶
Chapter 161 | Part 5: Infectious Diseases
KEY CLINICAL POINTS¶
- Gonorrhea is a sexually transmitted infection (STI) caused by Neisseria gonorrhoeae, primarily affecting the genital tract and leading to cervicitis, urethritis, and proctitis.
- Epidemiology shows a rising global incidence, with ~710,000 cases reported in the U.S. in 2021, disproportionately affecting young, nonwhite, and socioeconomically disadvantaged populations.
- Ceftriaxone is the first-line treatment for uncomplicated gonorrhea, but rising resistance necessitates alternative regimens like azithromycin and spectinomycin.
- Disseminated gonococcal infection (DGI) presents with arthritis, tenosynovitis, and skin lesions, requiring prompt systemic antibiotic therapy.
- Prevention includes condoms, partner notification, and vaccination (e.g., 4CMenB for meningococcal disease, which may reduce gonorrhea transmission).
1. DEFINITION & OVERVIEW¶
Gonorrhea is a sexually transmitted infection (STI) caused by Neisseria gonorrhoeae, primarily affecting the genital tract. It manifests as cervicitis, urethritis, proctitis, and conjunctivitis. Untreated infections can lead to pelvic inflammatory disease (PID), infertility, and disseminated gonococcal infection (DGI).
Table 161-1: Recommended Treatment for Gonococcal Infections¶
| Diagnosis | Treatment of Choice |
|---|---|
| Uncomplicated gonococcal infection of the cervix, urethra, pharynx, or rectum | Ceftriaxone (500 mg IM, single dose) plus Doxycycline (100 mg orally twice daily for 7 days) |
| Disseminated gonococcal infection (DGI) | Ceftriaxone (1 g IM or IV q24h) or Spectinomycin (2 g IM q12h) |
| Gonococcal conjunctivitis in adults | Ceftriaxone (1 g IM, single dose) |
| Ophthalmia neonatorum | Ceftriax0ne (25–50 mg/kg IV, single dose, not to exceed 125 mg) |
1.1 Microbiology¶
N. gonorrhoeae is a gram-negative, nonmotile diplococcus. It requires specific growth conditions (X and V factors) and is oxidase-positive. The organism has high antigenic variability due to its polygenic genome and can evade host immune responses.
1.2 Pathogenesis¶
N. gonorrhoeae adheres to mucosal surfaces via pili and outer membrane proteins (e.g., PorB, Opa). It evades complement-mediated lysis by binding to host proteins like factor H. Resistance to antibiotics is driven by chromosomal mutations and plasmid-mediated mechanisms.
2. EPIDEMIOLOGY¶
Gonorrhea incidence has risen globally, with ~710,000 cases reported in the U.S. in 2021. It disproportionately affects young, nonwhite, and socioeconomically disadvantaged populations. The disease is more common in developing countries, with high rates among aboriginal populations in Namibia and Australia. Risk factors include sexual behavior, lack of condom use, and asymptomatic carriage.
2.1 Demographics¶
The highest incidence occurs in individuals aged 15–24 years, with African American populations having the highest rates (652.9 per 100,000) and Asian populations the lowest (37.8 per 100,000).
2.2 Transmission¶
Transmission occurs via sexual contact, with higher rates among men who have sex with men (MSM) and individuals engaging in unprotected intercourse. Asymptomatic carriers contribute significantly to transmission.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
N. gonorrhoeae is a gram-negative diplococcus that colonizes mucosal surfaces. Its pathogenesis involves adherence to epithelial cells via pili and outer membrane proteins, evasion of host immune defenses, and resistance to antibiotics through chromosomal mutations and plasmid-mediated mechanisms.
Table 162-1: Characteristics of Type b and Nontypeable Strains of Haemophilus influenzae¶
| Feature | Type b Strains | Nontypeable Strains |
|---|---|---|
| Capsule | Ribosyl-ribitol phosphate | Unencapsulated |
| Clinical Manifestations | Meningitis and invasive infections in incompletely immunized infants and children | Otitis media in infants and children; lower respiratory tract infections in adults with chronic bronchitis |
| Vaccine | Highly effective conjugate vaccines | Protein D used as carrier protein in pneumococcal vaccine |
3.1 Antigenic Variation¶
N. gonorrhoeae exhibits antigenic variation through phase variation of surface proteins (e.g., Opa, PorB) and genomic rearrangements, enabling immune evasion and persistence.
3.2 Antimicrobial Resistance¶
Resistance to ceftriaxone and other antibiotics is increasing globally. Resistance mechanisms include chromosomal mutations (e.g., penA gene), plasmid-mediated β -lactamase production, and efflux pumps (e.g., MtrCDE).
4. CLINICAL FEATURES¶
Clinical manifestations vary by site of infection. In men, acute urethritis is common, while in women, cervicitis and PID are more prevalent. DGI presents with arthritis, tenosynovitis, and skin lesions. Neonatal infections cause ophthalmia neonatorum.
4.1 Men¶
Acute urethritis with purulent discharge, dysuria, and epididymitis. Asymptomatic carriers contribute to transmission.
4.2 Women¶
Cervicitis, endometritis, and PID. Symptoms may include vaginal discharge, dysuria, and pelvic pain. Untreated infections can lead to infertility.
4.3 Neonates¶
Ophthalmia neonatorum (conjunctivitis) and disseminated gonococcal infection (DGI) with systemic symptoms.
5. DIFFERENTIAL DIAGNOSIS¶
Differential diagnoses include chlamydial infections, herpes simplex virus (HSV), syphilis, and other STIs. In women, PID must be distinguished from other causes of pelvic pain and infertility.
5.1 Genital Ulcers¶
Differentiate from primary syphilis, genital herpes, and chancroid. HSV ulcers are typically grouped, while syphilitic chancres are painless and firm.
5.2 Arthritis¶
Distinguish DGI from reactive arthritis, rheumatoid arthritis, and septic arthritis. DGI typically presents with migratory joint pain and skin lesions.
6. INVESTIGATIONS & DIAGNOSIS¶
Diagnosis involves Gram stain, nucleic acid amplification tests (NAATs), and culture. NAATs are preferred for their high sensitivity and ability to detect both N. gonorrhoeae and C. trachomatis.
Table 161-1: Recommended Treatment for Gonococcal Infections¶
| Diagnosis | Treatment of Choice |
|---|---|
| Uncomplicated gonococcal infection of the cervix, urethra, pharynx, or rectum | Ceftriaxone (500 mg IM, single dose) plus Doxycycline (100 mg orally twice daily for 7 days) |
| Disseminated gonococcal infection (DGI) | Ceftriaxone (1 g IM or IV q24h) or Spectinomycin (2 g IM q12h) |
| Gonococcal conjunctivitis in adults | Ceftriaxone (1 g IM, single dose) |
| Ophthalmia neonatorum | Ceftriaxone (25–50 mg/kg IV, single dose, not to exceed 125 mg) |
6.1 Laboratory Tests¶
Gram stain of urethral or cervical secretions may show gram-negative diplococci. NAATs (e.g., COBAS AMPLICOR, Xpert® CT/NG) are highly sensitive for detecting N. gonorrhoeae.
6.2 Imaging¶
Ultrasound or MRI may be used to assess pelvic inflammatory disease or abscesses. X-ray may show signs of osteomyelitis or joint involvement in DGI.
7. MANAGEMENT & TREATMENT¶
Treatment regimens include single-dose ceftriaxone, azithromycin, and spectinomycin. For DGI, longer courses of antibiotics may be required. Partner notification and treatment are critical to prevent reinfection.
7.1 Uncomplicated Gonorrhea¶
First-line treatment: Ceftriaxone (500 mg IM) plus Doxycycline (100 mg orally twice daily for 7 days). Alternative regimens include azithromycin (2 g orally) or spectinomycin (2 g IM).
7.2 Disseminated Gonococcal Infection¶
Ceftriaxone (1 g IM or IV q24h) for 10–14 days. For severe cases, hospitalization and intravenous antibiotics are required.
7.3 Special Populations¶
Pregnant women require systemic antibiotics to prevent neonatal ophthalmia neonatorum. HIV-positive patients may require extended treatment due to immune compromise.
8. PROGNOSIS & COMPLICATIONS¶
Untreated gonorrhea can lead to PID, infertility, and DGI. Complications include ectopic pregnancy, chronic pelvic pain, and increased risk of HIV acquisition. Neonatal infections may cause blindness or sepsis.
8.1 Long-Term Outcomes¶
PID increases the risk of ectopic pregnancy and infertility. DGI may result in joint damage and chronic arthritis.
8.2 Public Health Impact¶
Gonorrhea contributes to the global burden of STIs, with rising antibiotic resistance complicating treatment. Prevention efforts focus on education, condoms, and vaccination.
9. SPECIAL CONSIDERATIONS¶
Pregnancy, pediatrics, and elderly populations require tailored management. Neonates need prophylactic eye drops to prevent ophthalmia neonatorum. HIV-positive patients require extended treatment and monitoring for drug resistance.
9.1 Pregnancy¶
Systemic antibiotics are required to prevent neonatal infection. Ceftriaxone is preferred due to its efficacy and safety in pregnancy.
9.2 Pediatrics¶
Children may present with asymptomatic infections or atypical symptoms. Partner notification is critical to prevent transmission.
10. KEY POINTS & CLINICAL PEARLS¶
- Ceftriaxone is the first-line treatment for uncomplicated gonorrhea, but resistance is increasing. 2. DGI requires systemic antibiotics and prolonged therapy. 3. Partner notification and treatment are essential to prevent reinfection. 4. Neonatal ophthalmia neonatorum is prevented with prophylactic eye drops. 5. HIV-positive patients require extended treatment and monitoring for drug resistance.