Lecture 27 Flashcards
What are the important bacterial STIs?
Chlamydia, Gnorrhoea and syphillus
What are the important viral STIs?
Human papilloma virus
herpes simplex
HIV
What are important fungal STIs?
Candidiasis
What is the important protozoal STI?
Trichomonas
What is the effect of Human Papilloma virus?
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
What are the features of the epidemiology of STIs?
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
Why might cervicitis not be noticed?
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
Which common STI (Chlamydia or Gonorrhoea) causes more serious urethritis?
Gonorrhoea is more severe however both infections are symptomatic
What type of infection from STIs can occur in both males and females?
Pharyngitis and/or procitis (inflammation in rectum)
What are the key differences between chlamydia and gonorrhoea?
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
How does gonorrhoea appear under the microscope?
Gram negative diplococci
What conditions can be caused by a neisseria gonorrhoea infection?
Urethitis, cervicitis, pharyngitis, proctitis, salpingitis, bacteraemia and arthritis
What is the risk of transmission of gonorrhoea?
Female to Male, 20% per episode
Male to Female 50% per episode
What it notable about antibiotic resistance of gonorrhoea?
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
What is the antibiotic typically used to treat gonorrhoea?
IM ceftriaxone
What are the amle and female rates of co0infection of chlamydia and gonorrhoea?
20% in Men
40% in Women
What is the lifecycle of chlamydia trachomatis?
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
What are the methods for diagnosis of chlamydia?
Cell Culture (slow and expensive)
Anitgen detection by microscopy or ELISA
PCR amplification of DNA
What are the treatments for a chlamydia infection?
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
What non-sexual diseases can be caused by chlamydia species?
Chlamydia Trachomatis- Trachoma
Chlamydia Pneumoniae- Pneumonia
Chlamydia Psittaci- Pneumonia
What pathogen causes syphillus?
Treponema Pallidum
What are the features of treponema pallidum?
Spiral Bacteria which cannot be grown in culutre
What is the progression of the disease of syphilis?
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
How is syphilis diagnosed?
Visualization of spirochaetes inchancre
Serology
What are the types of serological tests used to determine the presence of syphilis?
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
What spirochetes (other than syphilis) cause disease?
Treponema Pertenue- Ywas
Leptospira interrogans- leptospirosis
Borrelia brgdorferi- Lyme Disease
What spirochete can serology tests not distinguish between?
T.Pertenues and T.Pallidum
How is syphilis treated?
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
