Lecture 12 - STIs

Question 1

why do STIs require persistent infection?

Answer 1

to allow for occasional opportunities for transmission

Question 2

what do HPV, HIV, thrush and trichomoniasis have in common

Answer 2

they are all STIs

Question 3

how many STIs are acquired worldwide each day?

Answer 3

1 million, they have a massive burden

Question 4

what is urethritis?

Answer 4

symptom of STIs- inflammation of the urethra and can result in pus (purelent)

Question 5

what is cervicitis?

Answer 5

inflammation of the cervix, can be purulent)

Question 6

what is epididymitis?

Answer 6

inflammation of the epididymis
- chronic pain
- infertility
- hypogonadism
- defective hormone production

Question 7

what is pelvic inflammatory disease?

Answer 7

inflammation of the uterus, fallopian tubes and ovaries
- chronic pelvic pain
- ectopic pregnancy
- infertility

Question 8

what bacteria causes chalmidya?

Answer 8

chlamydia trachomatis

Question 9

how are the A-K serovars of chlamydia classified?

Answer 9

by prominent outer membrane protein OmpA

Question 10

what are the A-K serovars?

Answer 10

strains of chlamydia which effect the oculogenital region (which effect either the epithelium of the genital tract or the inner eyelids)

Question 11

what is lymphrgranuloma venerum?

Answer 11

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

Question 12

what type of disease do the L serovars of chlamidya cause?

Answer 12

invasive lymphgranuloma venereum

Question 13

how do the genital serovars of chlamydia effec men, women and babies?

Answer 13

> 70% of women are asymptomatic
~25% of men asymptomatic
can be passed to baby during childbirth, who could get conjunctivitis and pneumonia

Question 14

how do we cure genital chlamydia?

Answer 14

antibiotics

Question 15

what does genital chlamydia lead to if untreated?

Answer 15

can lead to pelvic inflammatory disease in 50% of asymptomatic women
in men, can lead to epididymitis, urethritis, reactive arthritis

Question 16

how many new chlamydia cases were there in 2020?

Answer 16

129 million

Question 17

chlamydia is not notifiable in NZ. what does this mean?

Answer 17

health practitioners are not legally required to report cases of chlamydia
- estimates are instead taken

Question 18

how do chlamydia rates in NZ compare to elsewhere?

Answer 18

comparatively higher

Question 19

how many new chlamydia cases were there in NZ in 2023 and 2024?

Answer 19

28,166 in 2023
533/100,000 in 2024

Question 20

what age bracket most commonly gets chlamydia?

Answer 20

20-24

Question 21

how is chlamydia diagnosed?

Answer 21

Patient presents with discharge or itching
- culture from swab or urine
- PCR
- Antigen detection by microscopy or ELISA

Question 22

what antibiotics are NOT effective against chlamydia?

Answer 22

penicillins and cephalosporins

Question 23

what is the current first line treatment for chlamydia?

Answer 23

single dose azithromycin, a macrolide. effective in 94% of patients, but less effective for rectal chlamydia

Question 24

what do we give people with rectal chlamydia?

Answer 24

the single dose azithromycin but also a 7 day 100mg twice daily dose of doxycycline

Question 25

describe chlamydia resistance?

Answer 25

no emergence of resistance

Question 26

how does chlamydia cause infection? elementary body -> reticulate body

Answer 26

- 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)

Question 27

how does chlamydia cause infection? reticulate body -> disease

Answer 27

- 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

Question 28

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?

Answer 28

100-1000

Question 29

which bacterium causes gonorrhoea?

Answer 29

neisseria gonorrhoeae

Question 30

what are the chances of passing gonorrhoea from men to women vs women to men?

Answer 30

w -> M = 20% chance per episode M -> W = 50%

Question 31

describe asymptomatic stats of M vs F for gonorrhoea

Answer 31

50% of women are asymptomatic only 5% of men are can be passes to baby

Question 32

what are the symptoms of gonorrhoea

Answer 32

pain and inflammation and burning during urination

Question 33

what happens if gonorrhoea is left untreated?

Answer 33

leads to systemic dissemination (lots of variation of diseases)

Question 34

true or false, gonorrhoea is a notifiable disease in nz

Answer 34

true, from 2017 it was made notifiable.

Question 35

how many cases of gonorrhoea were there in NZ in 2023?

Answer 35

7,794 in 2023, which is about 140 cases per 100,000

Question 36

how does our level of gonorrhoea compare to other countries?

Answer 36

comparitively higher

Question 37

true or false, gonorrhoea rates are rising in NZ

Answer 37

true, not just from reporting the disease

Question 38

how did rates of all STIs change over 2020-2022?

Answer 38

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

Question 39

what is the initial treatment for gonorrhoea?

Answer 39

penicillin was initially very effective, and not much was required because the minimum inhibitory concentration was less than 0.01 mg/L.

Question 40

what are the three processes of horizontal gene transfer?

Answer 40

- transformation (pick up free DNA, possibly from dead bacteria) - transduction (DNA from bacteriophage) - conjugation (bacteria to bacteria, major resistance mechanism)

Question 41

how did neisseria gonorrhoeae become more resistant to penicillin?

Answer 41

- 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

Question 42

what was the next antibiotic used against gonorrhoea after penicillin became resistant?

Answer 42

ciprofloxacin, a fluroquinolone. - mutants with an altered DNA gyrase brought up resistance

Question 43

what was the next antibiotic used against gonorrhoea after ciprofloxacin became resistant?

Answer 43

IM ceftriaxone with oral azithromycin - treatment has become more difficult and more expensive

Question 44

what percentage of gonorrhoea cases in NZ are diagnosed by culture vs by genetic material and what does this mean?

Answer 44

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.

Question 45

what is a co-infection we discussed?

Answer 45

chlamydia and gonorrhoea, 20% of men that have gonorrhoea also have chlamydia, and 40% of women

Question 46

what bacteria causes syphilis?

Answer 46

Treponema pallidum (spiral shaped)

Question 47

how many new cases of syphilis were there in 2020?

Answer 47

approximately 7.1 million became a notifiable disease in 2017

Question 48

why do we not know much about syphilis/treponema pallidum?

Answer 48

because it was only 2018 when we first discovered how to grow it in vitro

Question 49

what is the main primary disease symptom of syphilis?

Answer 49

Initial local infection = chancre (painless ulcer that heals spontaneously, and so people miss that they have one quite often)

Question 50

what is the secondary disease symptoms of syphilis?

Answer 50

2-8 weeks after primary symptom - bacteraemic dissemination = widespread rash. leads to rash, fever, malaise, aseptic meningitis, hepatitis etc

Question 51

what happens if the secondary phase of syphilis is left untreated?

Answer 51

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

Question 52

what is tertiary disease for syphilis?

Answer 52

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

Question 53

what happens with syphilis that is untreated during pregnancy?

Answer 53

half of pregnancies end in miscarriage or stillbirth

Question 54

true or false, women are more effected by syphilis than men

Answer 54

false, men have higher case numbers

Question 55

which is the only STI we discussed with a different most effected age bracket?

Answer 55

syphilis, most common in 30-39

Question 56

what is the treatment for syphilis?

Answer 56

penicillin at an effective blood level for 7 days, often intramuscular or intravenous (which isn't preferred bc stay in hospital)

Question 57

what is the resistance like in syphilis?

Answer 57

there is no resistance to anything