Lecture 26 - Sexually Transmissable Infections 1 Flashcards

1
Q

Which general organisms can cause STIs?

A
  • Bacteria
  • Viruses
  • Protozoans
  • Fungi
  • Arthropods (lice)
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2
Q

Which bacteria cause STIs?

A
  • Chlamydia trachomatis
  • Neisseria gonorrhoeae
  • Treponema pallidum
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3
Q

Where do STIs cause infection?

A
Female: all areas of genital tract
• vaginitis
• cervicitis
• endometritis
• salpingitis
• urethritis
Male: 
• urethritis
• epididymitis
• proctisis
• prostatitis
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4
Q

What is the name for inflammation of the Fallopian tubes?

A

Salpingitis

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5
Q

Why is dealing with STIs difficult?

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

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

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6
Q

What can salpingitis lead to?

A

Infertility

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7
Q

What are the common features of STIs?

A
  • Shared mode of transmission
  • Shared mode of prevention

• All may be asymptomatic

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8
Q

How is HIV transmitted

A

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

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9
Q

What does ‘STIs hunt in packs’ mean?

A

More than one infectious rate present at once

One infection facilitates the uptake of other agents as well

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10
Q

Under what conditions is HIV transmission rate increased?

A

Underlying STI → altered barriers

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11
Q

Can an infection be transmitted from asymptomatic individuals?

A

Yes

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12
Q

What is the main cause of damage in STIs?

A

Immune response

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13
Q

What are the animal reservoirs of the bacteria causing STIs?

A

No animal reservoir

Human pathogens only

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14
Q

In general, how are STIs treated?

A

Antibiotics

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15
Q

In general, how are STIs prevented?

A

Condoms

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16
Q

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

A

Chlamydia

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17
Q

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

A

Trachoma

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18
Q

What is trachoma?

How is it caused?

A

Ocular infection, scarring of eye and eyelids

Repeated infection with Chlamydia

Especially seen in Aboriginal populations in Australia

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19
Q

How can trachoma transmission be stemmed?

A

Eye washing

Because flies move the eye secretions between individuals

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20
Q

What do serovars D-K cause?

A
  • Conjunctivitis
  • Urogenital tract infections
  • Reactive arthritis
  • Pneumonitis
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21
Q

What do serovars L1-L3 cause?

Where are these infections commonly seen?

A

• Lymphogranuloma venereum

  • Invades lymph nodes of genital tract
  • Abscesses form
  • Africa, India, South America
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22
Q

What does Chlamydophila pneumoniae cause?

A

Atypical pneumonia

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23
Q

What does Chlamydophila psittaci cause?

What is this infection associated with?

A

Acute respiratory disease

Associated with birds

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24
Q

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

Why so many?

A

10,000

People don’t know they have it

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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