Pathogenesis of HIV and major STIs

Question 1

What is the difference between STI and STD?

Answer 1

Both transmitted through sexual contact

Disease = evidence of disease symptoms (infection could be asymptomatic!)

Question 2

What are genital infectious disease?

Answer 2

Disease not necessarily acquired by sexual contact but act can precipitate it

Examples inc commensal vaginal flora/GI flora

Question 3

What are the main bacteria associated with STIs?

Answer 3

N gonorrhoea
Chlamydia trachomatis
Ureaplasma
Mycoplasma

T pallidum - syphillis

Question 4

What does phthirus pubis cause?

Answer 4

Crabs

Question 5

What does sarcoptes scabiei cause?

Answer 5

Scabies

Question 6

What are the predominant sites of infection/disease?

Answer 6

Local e.g. T vaginalis, C trochomatis, HSV, HPV, N gonorrhoeae

Mixed - syphillis

Other sites - HIV, Hep B

Question 7

Other than sexual contact i.e. M-F, oral, M-M, F-F; how else can STIs be spread?

Answer 7

Vertical transmission - mother to baby

e.g. conjunctivitis/keratinits

Question 8

What is the risk of infection/acquisition mainly related to?

Answer 8

Number of sexual partners (without barriers/contraception)

Question 9

What type of bacteria is Neisseria gonorrhoea?

Answer 9

-Gram negative, -Diplococcus (looks like a pair of hairy balls) “clap”

Question 10

What are the characteristics of N gonorrhoeae?

Answer 10

• Intracellular pathogen - pathocytosed and multiplies intracellularly
• Pili on surface - attaches to surface mucosal membranes (mainly cuboidal/columnar epithelium)
• Cell envelope

Question 11

Where can gonorrhoea infect/effect?

Answer 11

Genital urethral tract
Rectum
Pharynx

Question 12

How does gonorrhoea present?

Answer 12

Majority of women = asymptomatic

Urethral discharge

Dysuria

Question 13

What are the complications of gonorrhoea (local and distant)?

Answer 13

• Epididymitis
• Prostatitis
• Pelvic inflammatory disease
• Fitz-Hugh curtis syndrome (perihepititis)

-Disseminated gonococcal infection - causes arthritis, meningitis

Question 14

What can N gonorrhoea cause in pregnancy?

Answer 14

• Spontaneous abortion,
• premature labour,
• conjunctivitis (ophthalmia neonatorum - blindness if not treated!!)

Question 15

How is gonorrhoea diagnosed?

Answer 15

• Urethral swab
• Culture
• Nucleic acid amplification test e.g. PCR

Question 16

What is the treatment for gonorrhoea?

Answer 16

Cephlasporins eg. cefixime (oral), ceftriaxone (IV)

Azithromycin

Question 17

What is the cause for non-gonococcal urethritis? (NGU)

Answer 17

Chlamydia

Ureaplasma urealyticum

Question 18

What type of bacterium is chlamydia trachomatis? In what two forms does it exist?

Answer 18

Obligate intracellular pathogen

Extracellular infective - elementary body

Intracellular replicative - reticular body

Question 19

What cells does chlamydia trachomatis target?

Answer 19

Squamocolumnar epithelium

Females - cervix, upper genital tract

Males/females - urethra, rectum, conjunctiva

Question 20

How does chlaymdia infection present?

Answer 20

Osten asymptomatic (females more)

Urethritis

Cervicitis - strawberry cervix

Dysuria/frequency (painful, burning pee!)

Question 21

What are the complications of chlamydia?

Answer 21

• Pelvic inflammatory disease - cause of infertility
• Conjunctivitis
• Epididymitis
• Tubal infertility
• Infant pneumonia

Question 22

How is chlamydia diagnosed?

Answer 22

NAAT (i.e. PCR)

Question 23

What is the treatment for chlamydia?

Answer 23

Azithromycin

Doxycycline

Question 24

What is the main cause of genital warts?

Answer 24

HPV 6 and 11

HP 16 and 18 = cervical cancer

Question 25

What is the treatment for genital warts?

Answer 25

Cervarix (16, 18) Gardasil (HPV 6, 11, 16, 18) - burn/freeze/cut

Question 26

What type of virus is the herpes simplex virus> Which one (type 1 or 2) causes genital herpes>

Answer 26

Double stranded DNA Type 2 - genital hypes

Question 27

What are the classical symptoms of genital herpes?

Answer 27

``` Pain Itching Dysuria Vaginal/urethral discharge Vesicles/ulcers - shedding (Spread) ``` CAN REACTIVATE

Question 28

What is the treatment for genital herpes?

Answer 28

Acyclovir

Question 29

What is the complications of Herpes?

Answer 29

Meningitis | Encephalitis

Question 30

How is genital herpes diagnosed?

Answer 30

Clinical, PCR (HSV 1 or 2), histology

Question 31

What bacteria caused syphilis? What type of bacteria is it?

Answer 31

treponema pallidum Spiralchaete (looks like a SPIRAL) Cannot be grown/cultured in lab

Question 32

How does it cause its symptoms and signs?

Answer 32

Penetrate intact mucosal membranes or abraded skin Disseminates through lymph and blood quickly Thereafter, causes symptoms and signs

Question 33

What does the primary stage of syphillis consist of? Time Pathology Symptoms

Answer 33

Incubation 3-90 days First chancre - site of inoculation, heals spontaneously within 3-6 weeks Asymptomatic

Question 34

What does the secondary stage of syphillis consist of? Time Pathology Symptoms

Answer 34

VERY INFECTIOUS -6-8 weeks after primary infection -Rash - trunk, limb, soles, palms -Condylomata lata - papules under armpits/genital regions - Malaise, fever, weight loss - CNS involvement - headache, meningism (rare)

Question 35

What does the latent/teriary stage of syphillis consist of? Time Pathology Symptoms

Answer 35

Spontaneous resolution after 3-12 weeks (latent = no clinical manifestation) Tertiary - >2yrs Gummas - non-specific granulomas (organs) - chronic inflammation Cardiovascular - aortic regurg/aneurysms Neuro - seizures, hemiplegia, mania/pyschoses/personality change, ataxic wide based gait Argyll Robertson pupils - constrict to accommodation but not light

Question 36

Can Syphillis cross the placenta and cause infection?

Answer 36

Yes - presents with snuffles/hepatosplenomegaly initially then saddle nose, frontal bosses, dental abnormalities later

Question 37

What is the treatment for syphillis?

Answer 37

penecillin

Question 38

What causes trichomoniasis? What is its characteristics?

Answer 38

Trichomoniasis vaginalis Protozoan, lacks mitochondria Humans only host

Question 39

What are the clinical characteristics of trichomoniasis? How is it diagnosed?

Answer 39

FROTHY GREEN VAGINAL DISCHARGE (mmmm...) Microscopy/culture

Question 40

How is trichomoniasis treated?

Answer 40

Metronidazole

Question 41

What is bacterial (anaerobic) vaginosis caused by?

Answer 41

Reduced vaginal lactobacilli Increased gardnerella vaginalis and anaerobes

Question 42

What is the characteristics of bacterial (anaerobic) vaginosis?

Answer 42

Watery discharge Fishy odour pH >4.5

Question 43

What are the treatment for bacterial vaginosis?

Answer 43

Metronidazole

Question 44

What is the cause for thrush? How is it transmitted?

Answer 44

Candida (usually albicans) Sex, broad spectrum antibiotics, diabetes (poorly controlled, oral contraceptives)

Question 45

What is thrush characterised by

Answer 45

Vaginal, vulval and penile erythema (redness) Itchiness Thick discharge

Question 46

How is thrush diagnosed and treated?

Answer 46

Clinical diagnosis/culture Treated with clotrimazole/fluconazole

Question 47

What is HIV marked by?

Answer 47

Loss of CD4 lymphocytes

Question 48

What are the characteristics of HIV?

Answer 48

Retrovirus - possesses reverse transcriptase RNA dependent DNA polymerase

Question 49

What HIV glycoprotein interacts with cell CD4 receptor and CCR5?

Answer 49

p120