STI Flashcards
What organism causes chlamydia
Chlamydia trachomatis
How long after exposure to chlamydia does one experience symptoms
1-2 weeks
List some complications of chlamydia infection
Pelvic Inflammatory Disease
chronic pelvic pain
infertility
ectopic pregnancy
arthritis
sterility in men (rare)
List 5 methods used to diagnose Chlamydia
- Antigen testing (direct immunofluorescence, ELISA)
- Cytology- Giemsa Staining
- Nucleic Acid BAsed test
- Culture
- Antibody detection
What method of diagnosis is the most sensitive for genital Chlamydia Trachomatis
Nucleic Acid Amplification Test (NAATs)
(Culture is the most specific, less sensitive than NAATs)
What specimen is collected for Chlamydia diagnosis
Cervical swab
Swab from penis
What is the treatment for chlamydia ?
- one single dose of Azithromycin
- a week of bd doxycycline
What serover of Chlamydia causes Genital Tract Infections ?
Serovers D-K
What serover of Chlamydia causes Eye Infection?
Serover A B C
What serover of Chlamydia causes Lymphogranuloma venerum
L1,L2,L3
When the McCoy culture with iodine is used to grow Chlamydia, what result will you see for a positive test
The McCoy or HeLa are used to grow Chlamydia , and a positive result will show brown Iodine stained-cytoplasmic inclusions in infected host cells
Stain brown with iodine due to glycogen granules
What are two methods of identifying chlamydia infection with McCoy cell culture?
Using Iodine stains
Fluorescent Antibody Test
What is the most sensitive and widely used test to identify chlamydia infection?
This is the Antibody Detection-complement fixation test and a titre of 1:64 and greater is diagnostic
What is the aetiological agent for Gonorrhea?
Neisseria Gonorrhea (gram negative bean shaped diplococci)
What symptoms do infected patients experience?
Males: burning on urinating, yellow/white discharge from penis
Females: fewer females experience symptoms, but they may experience urinary frequency, burning, hesitancy
List 5 complications of Gonorrhea
Pelvic Inflammatory Disease
Septicaemia
Arthritis
Endocarditis
Meningitis
What Specimen is collected to diagnose Gonorrhea
Endocervical swab
high Vaginal Swab
Urethral swab
Anal swab
Throat Swab
for disseminated gonococcal infections:
- blood culture
- synovial fluid
What are the specimen collected for gonorrhea testing placed before being sent to the laboratory?
- swab : placed in a transport medium like Stewart’s Medium
- blood: blood culture bottles
- joint fluid : in a universal container
List 4 lab investigations done to diagnose Gonorrhea
- Gram staining
- Culture with appropriate media
- Isolation Test
- Susceptibilty
What is the gram stain for N. gonorrhea
gram negative bean shaped diplococci, usually seen with pus cells
What media are inoculated to grow N. Gonorrhea ?
Chocolate Agar
Thayer - Martin Agar
What is Thayer- Martin Agar treated with to kill bacteria that form part of the normal GU flora, but still grow Neisseria. Gonorrhea?
CVBN
colistin
Vancomycin
Bactrim
Nystatin
What is done with the plates after they have been inoculated with Gonorrhea?
The inoculated plates are :
- incubated at 37oC
- in 5-10% CO2 (N.Gon is capnophillic)
- for 48hrs
Describe the N. Gonorrhea colonies
small grey colonies
True of false N. Gonorrhea are oxidase positive colonies
True - they turn black when the oxidase reagent is added to the culture medium
Which biochemical tests are used to differentiate between N. Meningitidis and N. Gonorrhea?
Glucose, Maltose, Sucrose test
N. G- glucose positive, maltose negative, sucrose negative
N. M- glucose positive, maltose positive, sucrose negative
How do we test if the N.Gonorrhea produces beta lactamases (which makes them resistant to penicillin)?
Cefinase Test
What aetiological agent causes Syphillis
Treponema Pallidum
Syphillis occurs in three stages: List the clinical features of the primary stage
- chancre at sites of infection (painless ulcers)
occurs 3-6 weeks after initial infection, and heals within 3-6 weeks without a scar
Syphillis occurs in three stages: List the clinical features of the secondary stage
1) Rash on the trunks (soles and palms) that can spread throughout the body-maculopapular rash
2) Alopecia
- onset 6weeks to 6months after initial infection if left untreated
- also : fever, malaise, hepatosplenomegaly, generalized lymphadenopathy, sore throat, arthralgia, anorexia etc
List the three dermatological manifestations of Secondary Syphilis
- maculopapular rash
- condylomata on genitals
- mucous patches on mouth ,tongue (round grey lesion)
What are the three general categories of tertiary syphilis and describe the features in each
Gummatous syphilis: painless noninfectious lesions found in skin and bones that can lead to scarring
Cardiovascular Syphilis
Neurosyphilis: Tabes Dorsalis (dorsal column affect), ataxia, general paresis of insane (GPI)- delusions of grandeur, depression, demetia
Describe what the term asymptomatic neurosyphilis means
There is a presence of treponems in the CSF with no clinical manifestations of infection
Treponema Pallidum crosses the placenta blood barrier, to the fetus and may cause what complications
- stillbirth
- spontaneous abortion
- neonatal death
List 4 clinical manifestations of Late Congenital Syphillis
- Hutchinsons’s triad : hutchinson’s teeth, 8th nerve deafness, interstitial keratitis
- Sabre Shins :anterior tibia bowing
- Perforation of the palate
- Clutton’s Joint
List the specimen collected for diagnosis of each stage of syphilis
Primary: chancres scrapings, fluid
Secondary : blood
Tertiary: CSF
What is the name of the test used to diagnose Syphilis
Treponemal Test
- Fluorescent Treponemal Antibody Absorption Test FTA-Abs
List two examples of non-treponemal tests used for Syphilis Screening
VDRL
Rapid Plasma Reagin (RPR)
Diagnosis of Syphilis can be done using Direct examination methods or Serology tests.
What can be observed in dark field microscopy ?
Tiny helical-shaped organisms moving in a cork-screw like fashion
How long after the appearance of the first primary lesion (chancre), will the VDRL test positive ?
1-2 weeks
note VDRL is useful in diagnosing congenital syphilis, and for monitoring treatment
Describe how the VDRL test for syphilis works
The VDRL test measures the antibodies formed against the different substances released from cells infected with the t.pallidum organism. So the antibodies bind to the substances released from the cell» flocculation. The test can be Reactive, Weakly Reactive or Non Reactive
We use the lowest titre that is reactive
In order for the blood specimen to be tested with the VDRL test, what has to be done?
- collected and allowed to clot
- serum separated from sample
- placed in incubation at 56oC for 30mins
- cooled to rt for testing
What is the treatment for Syphilis ?
Penicillin G- parenteral
What should be used to treat a penicillin allergic patient who has syphilis ?
Tetracyclin-HCl
What is the treatment for syphilis >1yr duration
Benzathine-penicillin G
What is the treatment for neurosyphilis ?
Aqueous Crystalline Penicillin G + Benzathine Penicillin G = IM weekly for 3 consecutive weeks
OR//
Aqueous procaine penicillin G = for 10days + 3 weeks of benzathine penicillin
What is BActerial VAginosis?
It is a poly microbial syndrome characterized by replacement of normal H2O2 producing lactobacilli with Anaerobic bacteria,
Gardnerella vaginalis
What is seen under the microscope with a vaginal discharge sample positive for Bacterial Vaginosis?
- Gram Stain : epithelial cells covered with gram positive bacilli - CLUE CELLS
What are the criteria used to diagnose bacterial vaginosis
- Clue Cells
- Positive Wiff test ( fishy odour after KOH added to discharge sample)
- pH high
What is the most sensitive test for trichomoniasis vaginalis
Diamond Media for Culture
