Bacterial STI Flashcards
What are 4 consequences of untreated STIs in women?
- Pelvic Inflammatory Disease (PID)
- Infertility
- Ectopic pregnancy
- Cervical cancer
What are 2 consequences of untreated (vertically transmitted) STIs in infants?
Eye infections: result in blindness and sepsis
What are 2 consequences of untreated STIs in men?
Infertility and narrowing of the urethra
What are 5 risk factors for chlamydia/gonorrhoea?
- Age < 25 years
- Street youth, homeless
- New sexual partners
- > 2 sexual partners / year
- Non-barrier contraception
What is a classic symptom of gonorrhoea in males and females that is absent from chlamydia? What is a typical clinical manifestation of it in men and women?
Considerable amounts of discharge
Acute urethritis (males) / cervicitis (females)
Where are two other areas that gonorrhoea can show symptoms?
Ano-rectal gonorrhea
Pharyngeal gonorrhea
What are two possible outcomes if gonorrhoea is ;eft untreated?
- Pelvic inflammatory disease (PID)
2. Septic arthritis
What is the risk of transmission from an infected woman to a man?
about 20 percent
What is the risk of transmission from an infected man to a woman?
about 50 %
Is there a risk risk of transmission of gonorrhoea from anal sex?
yep
Where does a gonorrhoeal infection typically manifest in an infant after perinatal transmission?
in the eyes
What are two major virulence factors of gonorrhoea that also mediate attachment?
- Pili
2. Outer membrane
What is the role of pili in the virulence of gonorrhoea?
Allows them to attach to mucosal surfaces and evade killing by macrophages
What is the role of the OM in the virulence of gonorrhoea? (2 things)
- proteins (OMP’s) facilitate invasion of epithelial cells
2. lipooligosaccharides (LPS) possess endotoxin activity, results in ciliary death
What two cell types are primarily infected by N. gonorrhoea?
columnar or cuboidal epithelium
How long does it take for the epithelial cells to be penetrated by N. gonorrhoea?
20-24 hours
What is the first line defense/first symptoms of a gonorrhoeal infection?
- Aggressive neutrophil response results in sloughing off of epithelial cells
- Exudation of pus/discharge
What is sensitivity a measure of?
A measure of the proportion of actual positive tests that are correctly identified
What is specificity a measure of?
A measure of the proportion of negative tests that are correctly identified
What is the positive predictive value? What is the value dependent on?
the proportion of patients with positive test results who are correctly diagnosed.
Its value is dependent on the prevalence of the disease.
What is the negative predictive value ?
The proportion of patients with negative test results who are correctly diagnosed
What are the preferred forms of specimens for a gonorrhoeal test for men and women?
Women: vaginal swab
Men: 1st voided urine
What kinds of media will gonorrhoea grow on? Which will it not? What are the growth conditions required? How long?
TMA, MLA, NYCA
- nutritious media with lots of antibiotics
WON’T grow on SBA
needs 5% CO2, 35ºC, 24-72 hours
What are 3 common forms/types of resistance that gonorrhoea has developed?
- ß-lactamases on plasmids
- Fluoroquinolone resistance
- tetracycline resistance
What are the two current drug recommendations for treatment of gonorrhoea? When do you use either?
- 800 mg Cefixime (orally) - uncomplicated urogenital
- this is the only oral agent available - 250mg Ceftriaxone (intramuscular injection)
- can be used to treat all forms of gonorrhoea (anal, pharyngeal..)
What class of drugs do the gonorrhoea drugs belong to?
the cephalosporins
What are the 3 species of chlamydia?
C. psittaci, C. pneumoniae, C. trachomatis
What kind of lifecycle does chlamydia have? What are the two forms and what do they infect?
Biphasic life cycle
The elementary body is the infectious form that enters host cells
Develops into the reticulate body which undergoes binary fission
How long is the incubation period for chlamydia in men?
7-21 days
What % of men are asymptomatic? Women?
about 25% of men and 80% of women
What makes controlling PID difficult in women with chlamydia?
The majority of women with cervicitis (80%) are asymptomatic and have normal cervical exam
What is a classic symptom of chlamydia in women?
urethritis
What is the go to lab test to detect chlamydia?
PCR of specimen
What is the first line treatment of chlamydia?
1 gram Azithromycin (oral, single dose)
What is the second line treatment for chlamydia?
100mg BID doxycycline (oral, 10 days)
What bacteria causes chancroid?
Haemophilus ducreyi
What are chancroid lesions?
Tender non indurated irregular ulcers
What is the spread of infection from Haemophilus ducreyi?
Infection is localized, however frequently spreads to regional lymph nodes
Lymph nodes enlarged and painful
- tend to be in the groin area
What is the morphology like for Haemophilus ducreyi? Intra or extracellular?
Intra or extracellular depending
pleomorphic cocco-bacilli or short rods.
What does a gram stain of Haemophilus ducreyi look like?
gram stain variable
Bipolar staining
Arranged in parallelchains = school of fish or rail road trackappearance
How do you culture H. ducreyi? What are the media requirements?
Gonococcal agar-based or a Mueller–Hinton-based medium is best
- can use a mixture of two media bases best
Need to add:
- 1% IsoVitalex
- 5% chocolatized horse blood or 1% hemoglobin
- 5% fetal calf serum (FBS)
- Vancomycin
