Sexually transmitted infections Flashcards
what is the predominant colonising species of the vaginal microbiome
Lactobacillus
how does lactobacillus inhibit growth of pathogenic species in the vagina
- Produce lactic acid – helps maintain low pH. (prevents growth of many invading species)
- Adhere to vaginal epithelial cells (create biofilm) and prevent long-term colonisation by other species.
- Produce hydrogen peroxide (antimicrobial compound)– inhibits growth of other microorganisms directly or via human myeloperoxidase
- produce antimicrobial peptides - bacteriocins
what pathogens can be inactivated by lactobacillus in the vaginal microbiome
HIV-1, herpes simplex virus type 2, Trichomonas vaginalis, Gardnerella vaginalis, Peptostreptococcus bivia and E. coli.!!!
what antimicrobial components of semen
antibacterial peptides including: – Lysozyme – Lactoferrin – Phospholipase A2 – Secretory leukocyte protease inhibitor – Semenogelin 1-derived peptides
give some features of gonorrhoea
caused by Neisseria gonorrhoeae. different manifestations, characterised by symptoms and disease profile. can be uncomplicated or disseminated.
how is gonorrhoea transmitted
almost always transmitted sexually in adults:
– genital – genital; genital – anorectal; orogenital; oro – anal
– autoinoculation of the eye
where is the uncomplicated gonorrhoeal infection found
localised, affecting the mucous membranes of urethra, endocervix, rectum, pharynx and conjunctiva.
whats the difference between uncomplicated and disseminated gonorrhoea
Uncomplicated infection is localised, usually affecting the mucous membranes of urethra, endocervix, rectum, pharynx and conjunctiva. Less common (< 1% people) is disseminated gonorrhoea – (spreads to other areas of the body) can present as septic arthritis or dermatitis
what are the complications of gonorrhoea for men
epididymitis, penile lymphangitis, per-urethral abscess, acute prostatitis, seminal vesiculitis.
what are the complications of gonorrhoea for women
• Bartholin’s abscess
polymicrobial infection.
• 10 – 20% pelvic inflammatory disease.
• During pregnancy, can cause spontaneous abortion, premature labour, early rupture of fetal membranes, etc.
• Disseminated gonorrhoea
• Rare but serious – lead to arthritis-dermatitis syndrome, gonococcal bacteremia and gonococcal endocarditis
give 5 features of Neisseria gonorrhoeae
Fastidious, Gram negative diplococci.
Facultatively intracellular
what are the virulence factors of Neisseria gonorrhoeae
Pilus – attach to epithelium. Contain constant & hypervariable regions, contribute to antigenic diversity.
Por proteins – form pores in membrane. Antigenic properties.
Opa proteins – aid in attachment.
LOS – contains lipopolysaccharide, has endotoxin activity.
Rmp proteins – inhibit bacteriacidal action of semen.
IgA protease – destroys IgA1.
Capsule - can resist phagocytosis.
what is used for the initial diagnosis of gonorrhoea
Nucleic acid amplification tests (NAATs) (gonorrhoea is hard to grow this is better than culture methods)
what is the current treatment for gonorrhoea
a single dose of 500 mg of intramuscular ceftriaxone.
what is the most common curable STI in the UK
Chlamydia
what is chlamydia caused by
obligate intracellular bacterium, Chlamydia trachomatis
where does Chlamydia trachomatis infect in men
the urethra
where does Chlamydia trachomatis infect in women
endocervix or urethra or both.
what percentage of chlamydia infections are asymptomatic
At least 70% women/50% men
what are the two types of chlamydia infection, how do they differ
- Uncomplicated – if not ascended into upper genital tract.
* Complicated – if in upper genital tract, causing pelvic inflammatory disease (PID) (women), epididymo-orchitis (men).
what complications can chlamydia cause
- Epididymo-orchitis – pain, swelling or inflammation of the epididymous and/or testicles.
- Adult conjunctivitis – mainly caused by autoinoculation.
- Lymphogranuloma venereum (LGV) – infection of lymphatic system.
- Sexually acquired reactive arthritis (SARA) – polyarthritis of weight-bearing joints.
- Anxiety and distress.
- In pregnancy, can result in increased risk of membrane rupture, pre-term delivery, low birth weight, etc.
how is chlamydia diagnosed
Nucleic acid amplification tests (NAATs)
what are the virulence factors of Chlamydia trachomatis
- Outer LPS cell membrane contains cysteine-rich proteins, inhibit phagosome fusion.
- Adhesion to sialic acid receptors on mucous membranes, presence at sites inaccessible to phagocytes, T cells and B cells.
- Antigenic variation so many serotypes. – harder to target
- Needle-like projection type III secretion apparatus – injects bacterial proteins into cell cytoplasm, avoids lysosomes. – so it isn’t registered as foreign as quickly
- Infested vacuole can divert lipids to itself rather than another part of the host cell.
describe the unique lifecycle of Chlamydia trachomatis
metabolically inert, spore-like elementary bodies (EBs) infect host cells and develop into metabolically active, replicative reticulate bodies (RBs) within a membrane-bound inclusion. RBs redifferentiate into EBs 24–48 hours after infection (once they reach a certain number) and the EBs are eventually released by lysis of the host cell and go on to infect other host cells
