Sexually Transmitted Bacterial Infections Flashcards
How many cases of STIs are seen a year?
333 million new cases p.a.
What age are the majority of individuals who have STIs?
<25 years old
How are STIs transmitted primarily?
Genital, oral/genital, anal/genital contact
What do STIs usually lead to?
Preventable infertility
Why are STIs increasing and becoming more difficult to control?
Increasing density and mobility of populations
Difficulty in changing human sexual behaviour
General level of promiscuity and tendency for increased number of sexual partners
Absence of vaccines for almost all STIs
Belief that most STIs are treatable
What are the top bacteria STIs?
Neisseria gonorrhoeae- gonorrhoea
Chlamydia trachomatis- non-specific urethritis
Treponema pallidum- syphilis
Haemophilus dureyi- chancroid
What are the top virus STIs?
Papillomaviruses- genital warts etc.
Herpes simplex- genital herpes
HIV- AIDS
Hepatitis B- hepatitis
What are the top fungi STIs?
Candida albicans- vaginal thrush
What are the top protozoa STIs?
Trichomonas vaginalis- vaginitis, urethritis
What bacterium cause gonorrhoea?
Neisseria gonorrhoeae
What is the structure of neisseria gonorrhoeae?
Non-motile, gram-negative diplococcus
Where is neisseria gonorrhoeae carried?
Genital tract
Nasopharynx
Anus
How many new cases are there of gonorrhoea a year?
62 million
What are the chances of getting gonorrhoea after a single encounter with an infected partner?
Female 50%
Male 20%
What are the symptoms of gonorrhoea?
Males- urethritis, purulent discharge and dysuria (painful urination)
Females- initial urethritis or cervicitis, often mild, spread to uterus (endometritis), oviducts (salpingitis) and pelvic inflammatory disease
What percentage of males and females have asymptomatic for gonorrhoea?
80% females
10% males
What are the stages of pathogenesis for gonorrhoea?
Entry and Adhesion o Following entry, bacteria attach to the columnar epithelium via pili Non-piliatd strains are non-infective Rapidly multiply o Some localised, others become systemic Invades epithelial cells and multiplies within vacuoles, protected from antibodies and phagocytes IgA protease Resist Serum killing by complement
What is the antigenic variation?
Capacity to genetically change surface structures
What is Pili and outer-membrane proteins (POMPS)?
For adhesion to mucosal epithelium have hypervariable regions and undergo frequent alteration
What are the vaccines for gonorrhoea?
None available
What is the treatment for gonorrhoea?
Single injection of high dose antibiotic (extended spectrum penicillin)
Rapidly becoming untreatable
What is chlamydia?
Very small bacteria o Obligate intracellular parasites o Unique life cycle o STI associated Chlamydia trachomatis Small genome 1 x 106 kb (1/4 that of E. coli)
What bacterium causes chlamydia?
Chlamydia trachomatis
What are the symptoms of chlamydia?
Many infections are asymptomatic
