7. STIs

Question 1

What is an STI?

Answer 1

an illness caused by an infectious microorganism with a propensity for transfer between humans through sexual contavt

Question 2

Who is affected by STI?

Answer 2

• young people with high risk sexual lifestyles
• men who have sex with men (MSM)
• disadvantaged socio-economic communities

Question 3

Which bacteria cause STI?

Answer 3

• chlamydia trachomatis
• neisseria gonorrhoea
• treponema pallidum (syphilis)

Question 4

What viruses cause STI?

Answer 4

• papillomavirus HPV; genital warts
• Herpes simplex HSV; genital herpes
• Hepatitis B/C; Hepatitis
• HIV; AIDS
• Monkeypox; rash and blisters

Question 5

What fungi causes STI?

Answer 5

candida albicans; thrush

Question 7

What parasites cause STI?

Answer 7

Trichonomoas vaginalis; vaginitis

Question 8

What arthropods (insect) cause STI?

Answer 8

• sacroptes scabei; genital scabies
• phthirus pubis; pediculosis pubis

Question 9

What factors cause STI?

Answer 9

• multiple partners
• pregnancy; morning after pill
• internet chat rooms
• dugs/alcohol
• MSM/TPSM
• contraceptive pill
• lack of education/ awareness

Question 10

How is chlamydia transmitted?

Answer 10

• vaginal/anal/oral sex
• mother to baby
• incubation: 1-3weeks

Question 11

What is the clinical manifestation of chlamydia?

Answer 11

• frequently asymptomatic (75% F, 25%M)
• M; urethritis (watery. mucoid discharge)
• F; urethritis, cervicitis, vaginitis

Question 12

What are the complications of chlamydia?

Answer 12

• pelvic inflammatory disease
• infertility in men and women; ascend to ovaries and testicles
• ocular infection; neonates/ adults

Question 13

What is chlamydia?

Answer 13

an obligate intracellular organism; cant be cultured

Question 14

What is the NCSP?

Answer 14

National Chlamydia Screening Programme
- control and prevention programme
- aim; detection/treatment of asymptomatic carriers
- target population; under 25s (sexually active)
method; obligate intracellular NAAT (PCR)8

Question 15

What is the treatment for Chlamydia?

Answer 15

Azithromycin (clamelle)- single dose 2 x 500mg
Doxycycline (vibramycin) - 7-14days 200mg

Question 16

What is the transmission of genital warts (HPV)?

Answer 16

• vaginal/ana/oral sex
• incubation; 1-6month, years
• greatest prevalence in 17-33 YOA

Question 17

What are the clinical manifestations of HPV?

Answer 17

• warts- 90 types, multiple, dry, keratinised, cauliflower appearance, painless

Question 18

What can HPV cause?

Answer 18

serotypes 16/18 can cause:
neoplasia - cancer
- neoplasmic conversion; cervical cancer

Question 19

What is the treatment for HPV?

Answer 19

• genital warts; podophyllin (cytotoxic) and imiquimod (immunostimulatory)
• cervical/intraurethral; carbon dioxide laser removal

Question 20

How can HPV be prevented?

Answer 20

• vaccination (protects against serotypes 6, 11, 16, 18) for 13 y/o
• safe sex

Question 21

How is herpes transmitted?

Answer 21

• vaginal/oral/anal sex
• incubation 3-7 days

Question 22

What is the clinical manifestation for primary infection of Herpes?

Answer 22

• 70% asymptomatic
• symptoms; constitutionalised and localised
• untreated attack lasts 28 days

Question 23

What is the clinical manifestation for reactivation of Herpes?

Answer 23

• tenderness, pain and burning to site of eruption lasting 2hrs - 2 days
• women; lesion on labia and perineum
• men; lesions in shaft, prepuce, glans
  lesions heal in 7-10 days; can get dissemination and encephalitis

Question 24

How can herpes be treated/prevented?

Answer 24

• Acyclovir (Zofirax): 200mg 5x a day for 7 days
• Famciclovir (Famvir): 200-250mg 3x a day for 7 days
• safe sex

Question 25

What is the microorganism that causes gonorrhoea?

Answer 25

- Neisseria gonorrhoeae - gram negative diplococcus - intracellular survival - strict human pathogen

Question 26

What is the transmission of Gonorrhoea?

Answer 26

- vaginal/oral/anal sex - incubation; 2-7days - transmission rates; 80% female, 20% male - mother to baby transmission

Question 27

What is the epidemiology of gonorrhoea?

Answer 27

- higher in urban areas - men form 70% of diagnoses; MSM, black ethnic groups - female 16-19, men 20-24

Question 28

What is the clinical manifestation of gonorrhoea?

Answer 28

male 10% female 70% male: - urethritis - dysuria - thick, purulent penile discharge female: -dysuria - cervicitis - thick, purulent vaginal discharge -rectal infection: anal discharge -throat infection; tonsilitis, purulent exudate

Question 29

What are complication of gonorrhoea?

Answer 29

- males; epididymitis, prostatitis - females; spread to fallopian tubes (salpingitis), pelvic inflammatory disease and infertility - opthalmia neonatorum - disseminated gonococcal infection DGI

Question 30

What are the virulence factors in stage 1 of gonorrhoea pathogenesis?

Answer 30

adherence and endocytosis - Pili; nonciliated epithelial cells - Opa proteins and LOS (lipooligosaccharide) - Por proteins (parasite directed endocytosis)

Question 31

What are the virulence factors in stage 2 of gonorrhoea pathogenesis?

Answer 31

Avoidance of host defences - capsule; sialic acid from host to form capsule- molecular mimicry IgA protease

Question 32

What are the virulence factors in stage 3 of gonorrhoea pathogenesis?

Answer 32

Formation of transferrin and lactoferrin binding receptors - Tbp1, Tbsp2 - Lbp1

Question 33

What is the laboratory diagnosis of gonococcal infection? sample collection

Answer 33

- males; urethral swab - females; multiple samples: urethral, endocervical/ vaginal - other samples can be requested: throat, rectal, blood cultures - transport medium, eg. Stuart's

Question 34

What is the laboratory diagnosis of gonococcal infection? Non-culture techniques

Answer 34

- direct microscopy of discharge; presumptive diagnosis if positive; initiative treatment - nucleic acid amplification tests (NAAT); PCR-based: Rapid, detects/amplifies specific DNA; bacterial viability not essential

Question 35

What is the laboratory diagnosis of gonococcal infection?

Answer 35

Culture -enriched agar; blood/chocolate agar -selective agar; modified Thayer-Martin? New York city agar, vancomycin, colistin, nystatin, trimethrim - opaque, grey colonies

Question 36

How to identify N.gonorrheae?

Answer 36

- colonies: gram-negative diplococci - oxidase + - catalase + - CHO fermentation - Prolyl aminopeptidase

Question 37

What is the treatment and prevention of gonococcal infection?

Answer 37

- ceftriaxone 250mg, injection - cefixime 400mg oral singe dose - azithromycin 2g single dose -safe sex