Lecture 27

Question 1

What are the important bacterial STIs?

Answer 1

Chlamydia, Gnorrhoea and syphillus

Question 2

What are the important viral STIs?

Answer 2

Human papilloma virus
herpes simplex
HIV

Question 3

What are important fungal STIs?

Answer 3

Candidiasis

Question 4

What is the important protozoal STI?

Answer 4

Trichomonas

Question 5

What is the effect of Human Papilloma virus?

Answer 5

Causes warts on both outer and inner surfaces, this can result in cancers as warts in side the anal canal or vagina may not be noticed

Question 6

What are the features of the epidemiology of STIs?

Answer 6

Intimate contact is required for transmission resulting in a need for STIs to develop persistent infections
They can be passed on from mother to child
Rate of transmission of STI is dependent on how frequently sexual partners are changed
STIs may infect the genitals but may then disseminate to other regions of the body

Question 7

Why might cervicitis not be noticed?

Answer 7

There are no pain receptors on the cervix which can lead the patient to be unaware f an infection, there is often mucous discharge but this is not always noticed

Question 8

Which common STI (Chlamydia or Gonorrhoea) causes more serious urethritis?

Answer 8

Gonorrhoea is more severe however both infections are symptomatic

Question 9

What type of infection from STIs can occur in both males and females?

Answer 9

Pharyngitis and/or procitis (inflammation in rectum)

Question 10

What are the key differences between chlamydia and gonorrhoea?

Answer 10

Chlamydia is less severe and more common than gonorrhoea, but the two infections often coexist resulting in treatments for both being used even if only one infection is determined

Question 11

How does gonorrhoea appear under the microscope?

Answer 11

Gram negative diplococci

Question 12

What conditions can be caused by a neisseria gonorrhoea infection?

Answer 12

Urethitis, cervicitis, pharyngitis, proctitis, salpingitis, bacteraemia and arthritis

Question 13

What is the risk of transmission of gonorrhoea?

Answer 13

Female to Male, 20% per episode

Male to Female 50% per episode

Question 14

What it notable about antibiotic resistance of gonorrhoea?

Answer 14

It quickly developed strong resistance to penecillins, starting with mutations in porins and a new transpeptidase, eventually a beta lactamase was also acquired this lead to the MIC being so high that it can no longer be used
Also has resistance to ciprofloxacin as it has a mutant DNA gyrase

Question 15

What is the antibiotic typically used to treat gonorrhoea?

Answer 15

IM ceftriaxone

Question 16

What are the amle and female rates of co0infection of chlamydia and gonorrhoea?

Answer 16

20% in Men

40% in Women

Question 17

What is the lifecycle of chlamydia trachomatis?

Answer 17

Obligate intracellular bacteria which replicates inside the epithelial cells and then lyses the epithelial cell releasing many bacteria
This results in chronic infection with watery discharge and few other symptoms

Question 18

What are the methods for diagnosis of chlamydia?

Answer 18

Cell Culture (slow and expensive)
Anitgen detection by microscopy or ELISA
PCR amplification of DNA

Question 19

What are the treatments for a chlamydia infection?

Answer 19

Tetracyclines (doxycycline) which requires several dises
Macrolides such as (azithromycin) which remain active in the tissue for long peroids of time meaning that often only one dose is required
Penicillins and Cephalosporins are ineffective

Question 20

What non-sexual diseases can be caused by chlamydia species?

Answer 20

Chlamydia Trachomatis- Trachoma
Chlamydia Pneumoniae- Pneumonia
Chlamydia Psittaci- Pneumonia

Question 21

What pathogen causes syphillus?

Answer 21

Treponema Pallidum

Question 22

What are the features of treponema pallidum?

Answer 22

Spiral Bacteria which cannot be grown in culutre

Question 23

What is the progression of the disease of syphilis?

Answer 23

Initial local infection which forms a primary lesion (Local Chancre) which will heal after 3-6 weeks
If bacteraemia has occurred as a result of this 2-8 weeks after chancre formation conditions such as Rash, fever, malaise, adenopathy, aseptic meningitis, hepatitis there are then periods of relapse and recovery over 1-4 years
Many years after the initial infection organ disease develops due to small vessel vasculitis

Question 24

How is syphilis diagnosed?

Answer 24

Visualization of spirochaetes inchancre

Serology

Question 25

What are the types of serological tests used to determine the presence of syphilis?

Answer 25

Non specific antigen tests:
Cardiolipin Cholesterol lecithin (beef heart)
VDRL, RPR
These are cheap screening tests
Specific Anitgen tests:
Bacteria cultured in rabbit testicles
TPHA, FTA
This is the more expensive but more accurate test

Question 26

What spirochetes (other than syphilis) cause disease?

Answer 26

Treponema Pertenue- Ywas
Leptospira interrogans- leptospirosis
Borrelia brgdorferi- Lyme Disease

Question 27

What spirochete can serology tests not distinguish between?

Answer 27

T.Pertenues and T.Pallidum

Question 28

How is syphilis treated?

Answer 28

Penicillin can be used as there is no resistance
Blood levels of this must be kept high for 7 days, via Benzathine Penicillin IM 3 time weekly,
Penicillin G IV for 10 days