STI and Coinfections Summary

Intended Learning Outcomes

  • Understand main features of syphilis and gonorrhoea.

  • Know basic features of bacteria involved.

  • Comprehend relation of pathogen features to disease.

  • Understand diagnosis, treatment, and prevention strategies.

Overview of STIs

  • Common bacterial STIs: Gonorrhoea, Syphilis, Chlamydia.

  • Over 300,000 infections annually (WHO).

  • Viruses and parasites also cause STIs (HIV lecture).

Gonorrhoea Trends

  • Increasing diagnoses in England: 35,000 in recent years.

Challenges in STI Control

  • Pregnancy complications and infertility.

  • Asymptomatic transmission.

  • Stigma and antimicrobial resistance.

Treponema pallidum (Syphilis)

  • Obligate pathogen, small genome (1039 genes).

  • Transmission: sexual and congenital (serious).

  • Disease stages: Primary, Secondary, Tertiary.

Symptoms of Syphilis

  • Primary: Painless chancre after 3 weeks.

  • Secondary: Fever, headache, lesions.

  • Tertiary: Localized symptoms after many years.

Virulence of Treponema pallidum

  • Chronic infections evade immune response.

  • No LPS, few stimulatory outer membrane proteins.

  • Antigenic variation and CNS invasion.

Diagnosis and Treatment of Syphilis

  • Blood tests for antibodies.

  • Treatment with penicillin; no known resistance.

Neisseria gonorrhoeae

  • Gram-negative beta-Proteobacteria, oval-shaped diplococcus.

  • Identified via microscopy; sensitive to dehydration.

Colonization and Symptoms of Gonorrhoea

  • Colonizes mucosa, adheres, and invades cells.

  • Symptoms: pain, discharge; many females asymptomatic.

Virulence Factors of Neisseria gonorrhoeae

  • Adhesion via Opa protein and pili.

  • Molecular mimicry for immune evasion.

  • Release of cytotoxins affecting fertility.

Diagnostics and Prevention

  • Nucleic acid amplification tests, microscopy, culture tests.

  • Preventative measures: screening and treatment of pregnant women.

Treatment and Resistance of Gonorrhoea

  • Treatment options include penicillin, azithromycin, fluoroquinolone.

  • Rising antimicrobial resistance; need for second-line treatments.

New Approaches and Future Outlook

  • Clinical trials for new antibiotics against "super-gonorrhoea."

  • Vaccine development ongoing to reduce incidence.