Lecture 26 - Sexually Transmissable Infections 1 Flashcards Preview

MIIM20002 - Microbes, Infections, Responses > Lecture 26 - Sexually Transmissable Infections 1 > Flashcards

Flashcards in Lecture 26 - Sexually Transmissable Infections 1 Deck (89):
1

Which general organisms can cause STIs?

• Bacteria
• Viruses
• Protozoans
• Fungi
• Arthropods (lice)

2

Which bacteria cause STIs?

• Chlamydia trachomatis
• Neisseria gonorrhoeae
• Treponema pallidum

3

Where do STIs cause infection?

Female: all areas of genital tract
• vaginitis
• cervicitis
• endometritis
• salpingitis
• urethritis

Male:
• urethritis
• epididymitis
• proctisis
• prostatitis

4

What is the name for inflammation of the Fallopian tubes?

Salpingitis

5

Why is dealing with STIs difficult?

• Stigma
• Embarrassment
• Morals
• Tendency to ignore the infection

→ even though we have good treatment and prevention, we can't eradicate them

6

What can salpingitis lead to?

Infertility

7

What are the common features of STIs?

• Shared mode of transmission
• Shared mode of prevention

• All may be asymptomatic

8

How is HIV transmitted

• Sexual route
Also, other routes:
• needles
• congenital

9

What does 'STIs hunt in packs' mean?

More than one infectious rate present at once

One infection facilitates the uptake of other agents as well

10

Under what conditions is HIV transmission rate increased?

Underlying STI → altered barriers

11

Can an infection be transmitted from asymptomatic individuals?

Yes

12

What is the main cause of damage in STIs?

Immune response

13

What are the animal reservoirs of the bacteria causing STIs?

No animal reservoir

Human pathogens only

14

In general, how are STIs treated?

Antibiotics

15

In general, how are STIs prevented?

Condoms

16

Which is one of the most common STI in young people in Australia?

Chlamydia

17

What infections do Chlamidia trachomatis serovars A,B and C cause?

Trachoma

18

What is trachoma?
How is it caused?

Ocular infection, scarring of eye and eyelids

Repeated infection with Chlamydia

Especially seen in Aboriginal populations in Australia

19

How can trachoma transmission be stemmed?

Eye washing
Because flies move the eye secretions between individuals

20

What do serovars D-K cause?

• Conjunctivitis
• Urogenital tract infections
• Reactive arthritis
• Pneumonitis

21

What do serovars L1-L3 cause?

Where are these infections commonly seen?

• Lymphogranuloma venereum

• Invades lymph nodes of genital tract
• Abscesses form
• Africa, India, South America

22

What does Chlamydophila pneumoniae cause?

Atypical pneumonia

23

What does Chlamydophila psittaci cause?
What is this infection associated with?

Acute respiratory disease

Associated with birds

24

How many cases per year of C. trachomatis in Victoria?
Why so many?

10,000

People don't know they have it

25

Which sites are commonly infected with serovars D-K?

Cervix
Urethra
Pharynx
Rectum
(Conjunctivitis)

May also be:
- endometritis
- salpingitis
- epididymitis
- proctitis

26

What does serovar D-K infection present as?

Discharge in males and females
Watery (non-puralent)

27

Can chlamydia be spread congenitally?

Yes, during vaginal delivery, bacteria may get into eye or be inhaled

Conjunctivitis
Pneumonia

28

Describe the morphology of Chlamydiae spp.

Gram negative
V. small

No peptidoglycan

29

Why can Chlamydiae spp. be gram stained?

No peptidoglycan → can't be gram stained

30

Describe the LPS in Chlamidae spp.

Truncated
Not very endotoxic

31

Describe the replication of Chlamydia spp.

Obligate intracellular replication
because it is an energy parasite (required ATP)

2 stages:
• Elementary body (EB)
• Reticulate body (RB)

32

How do we culture Chlamydia?

Must be cultured in cells
Because it is an energy parasite

33

What are the EB and RB ?

EB: non-replicating
• infectious
• extracellular

RB: actively replicating
• intracellular
• non-infectious

34

Which cells does Chlamidae spp. infect?

Columnar epithelial cells

35

Describe Chlamydia entry into cells

1. EB bind with adhesins
2. Receptor mediated endocytosis
3. Lysosome doesn't fuse
4. Inclusion forms
5. EB → RB
6. RBs replicate inside inclusions
7. RB → EB
8. EB released in secretions
9. Spread to other people

36

What is an inclusion?

Fusion of endosomes containing chlamydia bacteria

Contain 200-1000 bacteria

37

How do bacteria in an inclusion get nutrients?

'Drinking straws' inserted into host cytoplasm

38

Which form of chlamydia is susceptible to anti-microbial agents?

Reticulate bodies only

39

What is the effect of IFN-gamma on chlamydia?
Where is this coming from?

• Prolonged RB phase
• Persistance
• Low grade chronic inflammation

IFN-gamma is coming from activated T cells

40

Describe the immune response to chlamydia

1. Infected epithelial cells produce chemokines and other inflammatory mediators
2. Influx of neutrophils, monocytes, DC, NK
3. T and B cell activation
4. Lymphocytes and macrophages form follicles
5. Chronic inflammation
6. Scar tissue formation

41

What toxin that chlamydia produces can cause damage?

hsp60
Heat shock protein

Persistent inflammation

42

How do we diagnose chlamydia infection?

1. Collect sample
2a. PCR
2b. EIA, immunofluorescence

43

What samples are collected for diagnosing chlamydia?

Cervical and urethral swabs
First pass urine

44

How is chlamydia infection treated?
Why these ones?

Tetracycline
Macrolide antibiotics
Azithromycin

They are good at penetrating into the cells

45

Describe the morphology of Neisseria gonorrhoeae

Gram negative
Diplococcus

46

Is Neisseria gonorrgoeaea hardy?

Not at all

Susceptible to drying
Susceptible to disinfectants
Extremely fastidious

47

In what conditions do N. gonorrhoeae grow best?

CO2 enriched

48

What are the clinical presentations of gonorrhoea?

Similar to chlamydia

49

Are symptoms always seen in gonorrhoea?

Females: Asymptomatic infection is common

Males: less so

50

To where does N. gonorrhoea somtimes spread in females?

Ascending genital tract:
Pelvic inflammatory disease

Disseminate throughout the body

51

Under what circumstances will babies get gonorrhoea?

Describe the infection in babies

Congenital transmission from their mothers

Extremely purulent conjunctivitis

52

Which groups are most commonly infected with gonorrhoea in Australia?

Men who have sex with men
Infection from overseas
- SE Asia sex tour

Aboriginal communities

53

What is important about gonorrhoea infections from overseas?

More profound antibiotic resistance

54

Which cells are infected by N. gonorrhoeae?

Columnar epithelial cells

55

Describe the gonorrhoea pathogenesis

1. Adhesins binds
2. Replicate on cell surface
3. Spread in mucosal secretions

(May occasionally infect cells and disseminate)

56

What are the gonorrhoeal adhesins?

Pili
Outer membrane proteins
Lipo-oligosaccharide

57

Describe dissemination of gonorrhoea

Strain specific
ie not all strains will do this normally

Dissemination occurs when there is poor complement and neutrophil activation (to keep it at the site)

58

How does gonorrhoea cause damage?

Inflammatory response

No exotoxins

59

Outline the inflammatory response to gonorrhoea

1. LPS and peptidoglycan interat w/ PRR
2. Pus, pain
3. TNF production → loss of ciliated epithelial cells
4. Avoidance of C' cascade and neutrophils

60

Which damage is more severe, that of chlamydia or gonorrhoea?

Gonorrhoea

61

What does TNF production during gonorrhoea infection bring about?

Loss of ciliated epithelia

62

Why is there poor complement and neutrophil activation in gonorrhoea infection?

Because the altered LPS doesn't stimulate this as well

63

How does gonorrhoea avoid antibody responses?

Antigenic variation
of the pili and surface proteins at high frequency

Escape the antibody response

64

Describe horizontal transmission of genetic material in gonorrhoea bacteria

Readily take up DNA from other sources
- plasmids
- transposons

Implications:
- rapid antibiotic resistance

65

How do we diagose gonorrhoeal infection?

1. Swab collection, discharge collection
2. Gram stain + microscopy
Males: presence of diplococci (intracellular and extra. is diagnostic

PCR

66

Which samples must be collected in order to perform PCR?

Urine
Vaginal swab

67

How do we culture N. Gonorrhoeae?

GC: gonoccocus medium
or Chocolate agar

Fastidious
Need to select out normal flora in sample

Won't grow on HBA

68

Describe the bi-plate

Both sides: lysed HBA (GC)

One side: antibiotic
- only gonococci will gorw
Other side: no antibiotics

This allows us to find the gonococci amongst the normal flora

69

Describe treatment of gonorrhoea

Check guidelines for 'Empiral' treatment

Beta-lactamase resistance cephalosporin
- Ceftriaxone

Azithromycin

70

What does Treponema pallidum cause?

Syphilus

71

Describe morphology and staining of T. pallidum

Spirochete: spiral rod

Can't be Gram stained
- need special Dark-ground microscopy

72

Describe the motility of T. pallidum

Corkscrew like movement
Periplasmic contractile flagella

73

Is T. pallidum hardy?

Not at all
Very labile

74

How do we culture T. pallidum?

non-culturable

75

Is syphilis common in Australia?

Rates dropped amongst homosexuals

Epidemics in heterosexuals recently
- fly-in fly-out mining communities

76

Can babies get syphilis?

Bacteria cross the placenta in utero

77

Are there always symptoms with syphilis?

Not always

Asymptomatic as well as symptomatic

78

In general, describe the stages of syphilis

1. Infection
2. Primary syphilis
3. Secondary syphilis
4. Tertiary syphilis

79

What is primary syphilis?

How long does it last?

• Local ulcer
• Chancre
(on penis)

Can be asymptomatic

• 2-6 weeks

80

What is secondary syphilis?
When does it occur?

How long does it last?

• Rash
• Warty genital lesions
• Lymphadenopathy

Occurs if the 1° infection isn't treated, or if asymptomatic

• Lasts up to 6 months

81

How long the asymptomatic period between 2° and 3° syphilis last?

3-30 years

82

When will syphilis infection be transmitted from person to person?

• Local ulcer
• Disseminated bacteria

83

What is tertiary syphilis?

• Gummas
• Eyes
• Ears
• Heart
• Brain

84

How is syphilis diagnosed?

1. Droplet from lesion
2. Dark-ground microscopy
3. PCR
4. Serology

85

What does serology tell us about T. pallidum?

Detection of antibodies to treponemal antigens

Cross reactive antibodies

86

Describe the features of the Rapid plasma reagin test

Measures antibodies made against cariolipin

Highly sensitive (few false negatives)
Not very specific (some false-positives)
Cheap

87

How is syphilis treated?

Penicillin

88

When are gummas seen?
What are they?

Tertiary Syphilis
They are a type of granuloma

89

What is controlling syphilis in the asymptomatic period?

• Macrophages
• Th cells
• B cells