(B) Lecture 16: Bacterial STDs Flashcards
Sexually transmitted disease
A RECOGNIZABLE DISEASE state that has developed from an infection
Sexually transmitted infection
A pathogen that causes INFECTION through sexual contact
Most common STIs
- HIV
- HPV
- Hepatitis virus
- Neisseira gonorrhoeae
- Chlamydia trachomatis
- Treponema pallidum
History of Syphillis
Treponema pallidum
- old disease (3000 BC)
- “stranger” disease
- mercury is first treatment for syph
- COMPOUND 606 was the first potent treatment
History of Gonorrhea
Neisseria gonorrhoeae
- not clear when it officially appeared
- some say it’s a disease from Ancient Greece
- SULFONAMIDES decreased incidence
History of Chlamydia
Chlamydia trachomatis
- HIDDEN disease under gonorrhoea and syph
- Eric Dunlop was first to identify C. trachomatis as the cause of this genital infection
- MOST COMMON bacterial STI since late 1990s
Obligate human pathogens
- must be in contact w/ their host to survive and replicate
- bacterial STDs have no other niche than human body (human-human contact is needed)
Treponema pallidum
agent of SYPHILLIS
- spirochetes
- unculturable (does not tolerate high temp, atmospheric O2 level)
- sexual or mother/child transmission
T. pallidum disease
- stage 1: no signs; maybe a sore
- stage 2: body rash
- stage 3: nothing visible outside; affects INTERNAL organs
T. pallidum virulence factors
- slow to grow but need FEW cells to transmit
- NO LPS and internal flagella
- evade immune response
- outer membrane proteins: attachment to epithelial cells (adheres to cell wall) and extracellular matrix
T. pallidum treatment
Diagnosis
- PCR
- serologic tests
NO vaccine available
Antibiotics treatment
- penicillin or doxycycline
Neisseria gonnorrhoeae
- gram-NEGATIVE bacteria
- diplococci
- non-motile (adheres to cell wall)
- obligate human pathogen
- sexual transmission and mother/child
N. gonnorhoeae disease
MORE POTENT than syphillis
Female
- abdominal pain
- increased vaginal discharge
- painful urination
- painful intercourse
- vaginal bleeding btwn periods
Male
- DISCHARGE/EXUDATE from penis -
- swollen testicles
- painful urination
- UTI
- inflammation of penile
N. gonnorhoeae gender differences
Females are usually asymptomatic
Men are usually SYMPTOMATIC
Gonococcal conjunctivitis
white discharge from eyes
especially seen in mother/child transmission
N. gonorrhoeae cycle
- adherence to urogenital epithelium
- competition w/ resident microbiota
- colonization + invasion of epithelium
- release of peptidoglycans
- cytokine, chemokine and inflammatory response
- influx of neutrophils; phagocytosis of N. gonorrhoeae
- neutrophil-rich EXUDATE helps w/ transmission
N. gonnorrhoeae virulence factors
Colonization/invasion:
- Type IV Pili
- Opa (Opacity protein)
- cell wall antigen (LOS)
- PorB (OM porin)
Immune modulation
- prevents complement activation, opsonization and bacterial killing
- modulates activities of macrophages, DCs and neutrophils
- modulates T cell function to avoid adaptive immunity
N. gonorrhoea treatment
Diagnosis
- PCR
- culture
NO vaccine available
Antibiotics RESISTANCE (Mtr efflux pump) - antibiotics pumped out before it effects target
Urgent need for new therapeutics
N. gonnorhoea antibiotic resistance
Antibiotics keep becoming resistant
Some antibiotics are no longer first-line antibiotics = keeps resistance low
Last resort: cephalosporin
Visible complication to gonorrhoea
White discharge/exudate from neutrophils
Chlamydia trachomatis
- gram-NEGATIVE bacteria
- thin or no PG layer
- obligatory INTRACELLULAR pathogen (must be inside human)
- sexual or mother/child transmission
C. trachomatis disease
MOST ppl are asymptomatic
Female = 80-90% asymptomatic
- cervicitis
- prolonged menses, spotting + discharge
- tubing infertility or ectopic pregnancy
Male = Up to 90% asymptomatic
- urethritis (inflammation of urethra)
- dysuria + penile discharge
C. trachomatis life cycle
Has 2 states: EB and RB
Elementary body = INFECTIOUS
Reticulate body = NOT infectious; made to REPLICATE; within cell
- infectious EB enters
- EB is circled by inclusion and differentiates to RB
- RB fuses and replicates
- persistent form reactivates; RB form differentiates to EB
- EB accumulates and is released then exocytoses
C. trachomatis virulence factors
LPS = presumably bind CFTR
MOMP (Major outer membrane protein) = mannose receptor on surface
Secretion system (T3SS, T2SS, T5SS)
- T3SS is the most important
- inject molecules that manipulate cytoskeleton to form inclusion around
C. trachomatis Treatment
Diagnosis
- PCR
- Culture
NO vaccine available
Antibiotics treatment
- Azithromycin or doxycycline
What body is infectious in C. trachomatis?
Elementary body
Syphilis summary
Treponema pallidum
- spirochete
- unculturable
- long time of growth/development of disease
Gonorrhea summary
Neisseria gonorrhoea
- diplococci (2 spheres) - coffee bean
- male usually symptomatic
Chlamydia summary
Chlamydia trichomatis
- small ring of PG
- MOST COMMON STIs
- male and female asymptomatic
- asymptomatic = so easy to transmit
Main treatments for STIs
Antibitocs are main treatment for STIs
We’re at our last resort for N. gonorrhoea
Association btwn STIs and HIV
STIs are bacterial while HIV is viral
- behaviours that put someone at risk of STIs are also associated w/ behaviours associated w/ risk of HIV
- sore or inflammation of reproductive tissue from an STD may allow infections w/ HIV that would be stopped by intact skin
Prevention of STIs
- not using condoms
- multiple partners
- anonymous partners
- consumption of drugs and/or alcohol
