Lecture 12 - STIs Flashcards
why do STIs require persistent infection?
to allow for occasional opportunities for transmission
what do HPV, HIV, thrush and trichomoniasis have in common
they are all STIs
how many STIs are acquired worldwide each day?
1 million, they have a massive burden
what is urethritis?
symptom of STIs- inflammation of the urethra and can result in pus (purelent)
what is cervicitis?
inflammation of the cervix, can be purulent)
what is epididymitis?
inflammation of the epididymis
- chronic pain
- infertility
- hypogonadism
- defective hormone production
what is pelvic inflammatory disease?
inflammation of the uterus, fallopian tubes and ovaries
- chronic pelvic pain
- ectopic pregnancy
- infertility
what bacteria causes chalmidya?
chlamydia trachomatis
how are the A-K serovars of chlamydia classified?
by prominent outer membrane protein OmpA
what are the A-K serovars?
strains of chlamydia which effect the oculogenital region (which effect either the epithelium of the genital tract or the inner eyelids)
what is lymphrgranuloma venerum?
aka LGV.
- bacterium infects macrophages and spreads through lymph nodes.
- predominantly in men who have sec with men
- results in buboes in the groin and proctolitis (inflammation of colon and rectum
what type of disease do the L serovars of chlamidya cause?
invasive lymphgranuloma venereum
how do the genital serovars of chlamydia effec men, women and babies?
> 70% of women are asymptomatic
~25% of men asymptomatic
can be passed to baby during childbirth, who could get conjunctivitis and pneumonia
how do we cure genital chlamydia?
antibiotics
what does genital chlamydia lead to if untreated?
can lead to pelvic inflammatory disease in 50% of asymptomatic women
in men, can lead to epididymitis, urethritis, reactive arthritis
how many new chlamydia cases were there in 2020?
129 million
chlamydia is not notifiable in NZ. what does this mean?
health practitioners are not legally required to report cases of chlamydia
- estimates are instead taken
how do chlamydia rates in NZ compare to elsewhere?
comparatively higher
how many new chlamydia cases were there in NZ in 2023 and 2024?
28,166 in 2023
533/100,000 in 2024
what age bracket most commonly gets chlamydia?
20-24
how is chlamydia diagnosed?
Patient presents with discharge or itching
- culture from swab or urine
- PCR
- Antigen detection by microscopy or ELISA
what antibiotics are NOT effective against chlamydia?
penicillins and cephalosporins
what is the current first line treatment for chlamydia?
single dose azithromycin, a macrolide. effective in 94% of patients, but less effective for rectal chlamydia
what do we give people with rectal chlamydia?
the single dose azithromycin but also a 7 day 100mg twice daily dose of doxycycline
describe chlamydia resistance?
no emergence of resistance
how does chlamydia cause infection?
elementary body -> reticulate body
- highly infectious, metabollically inactive elementary body is taken into the cell
- it grows an inclusion membrane and becomes an intermediate body
- then becomes metabolically active and replicative (reticulate body)
how does chlamydia cause infection?
reticulate body -> disease
- RB replicates within the inclusion membrane
- T3SS proteins penetrate the IM and secretes effectors
- RB replicates into EB, then the infectious EBs escape the cell via lysis or extrusion to initaite new infection
when the EBs in chlamydia are just about to leave the cell via lysis or extrusion, how many EBs are there in the inclusion membrane/cell?
100-1000
which bacterium causes gonorrhoea?
neisseria gonorrhoeae
what are the chances of passing gonorrhoea from men to women vs women to men?
w -> M = 20% chance per episode
M -> W = 50%
describe asymptomatic stats of M vs F for gonorrhoea
50% of women are asymptomatic
only 5% of men are
can be passes to baby
what are the symptoms of gonorrhoea
pain and inflammation and burning during urination
what happens if gonorrhoea is left untreated?
leads to systemic dissemination
(lots of variation of diseases)
true or false, gonorrhoea is a notifiable disease in nz
true, from 2017 it was made notifiable.
how many cases of gonorrhoea were there in NZ in 2023?
7,794 in 2023, which is about 140 cases per 100,000
how does our level of gonorrhoea compare to other countries?
comparitively higher
true or false, gonorrhoea rates are rising in NZ
true, not just from reporting the disease
how did rates of all STIs change over 2020-2022?
they dropped due to covid and isolation, then increased after isolation stopped.
testing reduced due to less available resources - they were all going towards covid test manufacturing
what is the initial treatment for gonorrhoea?
penicillin was initially very effective, and not much was required because the minimum inhibitory concentration was less than 0.01 mg/L.
what are the three processes of horizontal gene transfer?
- transformation (pick up free DNA, possibly from dead bacteria)
- transduction (DNA from bacteriophage)
- conjugation (bacteria to bacteria, major resistance mechanism)
how did neisseria gonorrhoeae become more resistant to penicillin?
- accumulation of mutations in porins and the acquisition of a gene for a new transpeptidase brought the MIC to 1mg/L
- plasmid with gene for beta lactamase brought it so 64mg/L, aka resistant to penicillin, the first line treatment
what was the next antibiotic used against gonorrhoea after penicillin became resistant?
ciprofloxacin, a fluroquinolone.
- mutants with an altered DNA gyrase brought up resistance
what was the next antibiotic used against gonorrhoea after ciprofloxacin became resistant?
IM ceftriaxone with oral azithromycin
- treatment has become more difficult and more expensive
what percentage of gonorrhoea cases in NZ are diagnosed by culture vs by genetic material and what does this mean?
only 25% culture. This means we dont know the suceptibility of antibiotics to the strain. e.g we are not looking for resistance in most cases.
what is a co-infection we discussed?
chlamydia and gonorrhoea, 20% of men that have gonorrhoea also have chlamydia, and 40% of women
what bacteria causes syphilis?
Treponema pallidum (spiral shaped)
how many new cases of syphilis were there in 2020?
approximately 7.1 million
became a notifiable disease in 2017
why do we not know much about syphilis/treponema pallidum?
because it was only 2018 when we first discovered how to grow it in vitro
what is the main primary disease symptom of syphilis?
Initial local infection = chancre (painless ulcer that heals spontaneously, and so people miss that they have one quite often)
what is the secondary disease symptoms of syphilis?
2-8 weeks after primary symptom
- bacteraemic dissemination = widespread rash. leads to rash, fever, malaise, aseptic meningitis, hepatitis etc
what happens if the secondary phase of syphilis is left untreated?
they will eventually recover, but if they don’t seek treatment they will get relapses and recoveries over the next 1-4 years.
- 1/3 of the people get tertiary disease
what is tertiary disease for syphilis?
small vessel vasculitis = inflammation of blood vessels affecting the brain and aorta
- so a sign of 3º disease is actually mental issues, because it effects the brain
what happens with syphilis that is untreated during pregnancy?
half of pregnancies end in miscarriage or stillbirth
true or false, women are more effected by syphilis than men
false, men have higher case numbers
which is the only STI we discussed with a different most effected age bracket?
syphilis, most common in 30-39
what is the treatment for syphilis?
penicillin at an effective blood level for 7 days, often intramuscular or intravenous (which isn’t preferred bc stay in hospital)
what is the resistance like in syphilis?
there is no resistance to anything
