Pathogenesis of HIV and major STIs Flashcards Preview

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Flashcards in Pathogenesis of HIV and major STIs Deck (49):
1

What is the difference between STI and STD?

Both transmitted through sexual contact

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

2

What are genital infectious disease?

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

Examples inc commensal vaginal flora/GI flora

3

What are the main bacteria associated with STIs?

N gonorrhoea
Chlamydia trachomatis
Ureaplasma
Mycoplasma

T pallidum - syphillis

4

What does phthirus pubis cause?

Crabs

5

What does sarcoptes scabiei cause?

Scabies

6

What are the predominant sites of infection/disease?

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

Mixed - syphillis

Other sites - HIV, Hep B

7

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

Vertical transmission - mother to baby
e.g. conjunctivitis/keratinits

8

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

Number of sexual partners (without barriers/contraception)

9

What type of bacteria is Neisseria gonorrhoea?

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

10

What are the characteristics of N gonorrhoeae?

-Intracellular pathogen - pathocytosed and multiplies intracellularly

- Pili on surface - attaches to surface mucosal membranes (mainly cuboidal/columnar epithelium)

- Cell envelope

11

Where can gonorrhoea infect/effect?

Genital urethral tract
Rectum
Pharynx

12

How does gonorrhoea present?

Majority of women = asymptomatic

Urethral discharge

Dysuria

13

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

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

-Disseminated gonococcal infection - causes arthritis, meningitis

14

What can N gonorrhoea cause in pregnancy?

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

15

How is gonorrhoea diagnosed?

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

16

What is the treatment for gonorrhoea?

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

Azithromycin

17

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

Chlamydia
Ureaplasma urealyticum

18

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

Obligate intracellular pathogen

Extracellular infective - elementary body

Intracellular replicative - reticular body

19

What cells does chlamydia trachomatis target?

Squamocolumnar epithelium

Females - cervix, upper genital tract

Males/females - urethra, rectum, conjunctiva

20

How does chlaymdia infection present?

Osten asymptomatic (females more)

Urethritis

Cervicitis - strawberry cervix

Dysuria/frequency (painful, burning pee!)

21

What are the complications of chlamydia?

-Pelvic inflammatory disease - cause of infertility

-Conjunctivitis

-Epididymitis

-Tubal infertility

-Infant pneumonia

22

How is chlamydia diagnosed?

NAAT (i.e. PCR)

23

What is the treatment for chlamydia?

Azithromycin
Doxycycline

24

What is the main cause of genital warts?

HPV 6 and 11
(HP 16 and 18 = cervical cancer)

25

What is the treatment for genital warts?

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

26

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

Double stranded DNA

Type 2 - genital hypes

27

What are the classical symptoms of genital herpes?

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

CAN REACTIVATE

28

What is the treatment for genital herpes?

Acyclovir

29

What is the complications of Herpes?

Meningitis
Encephalitis

30

How is genital herpes diagnosed?

Clinical, PCR (HSV 1 or 2), histology

31

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

treponema pallidum

Spiralchaete (looks like a SPIRAL)

Cannot be grown/cultured in lab

32

How does it cause its symptoms and signs?

Penetrate intact mucosal membranes or abraded skin

Disseminates through lymph and blood quickly

Thereafter, causes symptoms and signs

33

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

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

34

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

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)

35

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

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

36

Can Syphillis cross the placenta and cause infection?

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

37

What is the treatment for syphillis?

penecillin

38

What causes trichomoniasis? What is its characteristics?

Trichomoniasis vaginalis

Protozoan, lacks mitochondria

Humans only host

39

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

FROTHY GREEN VAGINAL DISCHARGE (mmmm...)

Microscopy/culture

40

How is trichomoniasis treated?

Metronidazole

41

What is bacterial (anaerobic) vaginosis caused by?

Reduced vaginal lactobacilli

Increased gardnerella vaginalis and anaerobes

42

What is the characteristics of bacterial (anaerobic) vaginosis?

Watery discharge
Fishy odour
pH >4.5

43

What are the treatment for bacterial vaginosis?

Metronidazole

44

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

Candida (usually albicans)

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

45

What is thrush characterised by

Vaginal, vulval and penile erythema (redness)

Itchiness

Thick discharge

46

How is thrush diagnosed and treated?

Clinical diagnosis/culture

Treated with clotrimazole/fluconazole

47

What is HIV marked by?

Loss of CD4 lymphocytes

48

What are the characteristics of HIV?

Retrovirus - possesses reverse transcriptase

RNA dependent DNA polymerase

49

What HIV glycoprotein interacts with cell CD4 receptor and CCR5?

p120

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