STDs - Diebel Flashcards
What are the four most common types of infections that people with STDs present clinically?
Urethritis
Cervicitis
Vaginitis and vaginosis
Genital ulcers
What are the common causes of Urethritis?
N. gonorrhoeae, C. trachomatis
What are the common causes of Cervicitis?
C. trachomatis
What are the common causes of Vaginitis?
T. vaginalis, C. albicans
What are the common causes of Vaginosis?
Gardnerella spp.
What are the 5 types and major causes of Genital Ulcers (Nonexudative Infections)?
Syphilis – T. pallidum Herpes – HSV-1 and HSV-2 Chancroid – H. ducreyi Lymphogranuloma venereum – C. trachomatis Genital warts – HPV
What are the common causes of Pelvic inflammatory disease (PID)?
Polymicrobic; N. gonorrhoeae, C. trachomatis, anaerobes
What are the clinical symptoms that are suggestive of particular genital diseases (Chlamydia, Gonorrhea, HPV/MCV, HSV-2, Syphilis)?
Anogenital malignancy – should be ruled out
Chlamydia – significant discharge usually present
Gonorrhea – significant discharge usually present
HPV / MCV – often leads to wart-like growths
HSV-2 – painful vesicles and shallow ulcers usually present
Syphilis – often painless, no wart lesions
What two diagnostic tests are used in HPV?
Pap smear - looking for giant cells
PCR tests for certain HPV types
What is the treatment for HPV?
warts or precancerous tissue can be removed to prevent spread, but virus is not treatable (incurable)
can self-resolve, but takes 1-2 years
Human Papilloma Virus classification:
dsDNA, Group I
Circular Genome
Icosahedral Nucleocapsid
Nonenveloped
Papovaviridae
Papillomavirus
What are the most common types of HPV that present as warts?
6 and 11
How does HPV replicate and cause cancer?
Warts: Tumorigenic => Carcinomas
Virus introduced to skin through foreign body or microabrasion => Get through mucosal barriers/layers => get into stem cells => use host DNA polymerase expressed by stem cells (no viral DNA polymerase)
What are the important proteins involved in HPV tumorgenesis?
E1 = binds to host DNA and uses ATP to create replication bubble => unwind DNA => recruit host DNA polymerase
E2 = loader protein, helps E1 attach to DNA
E6 = enhances the ability of host cells to move through the cell cycle by binding to E6AP and p53 to form a trimeric complex => p53 gets ubiquinated which targets it for degradation => stops DNA damage monitoring/repair/apoptosis => tumor cell progression
E7 = binds to Rb => Rb cannot bind to E2F => unbound E2F => uncontrolled transcription factor promotion of S-phase => persistent replication => tumor cell progression
What for organisms can cause urethral discharge in sexually active men?
Chlamydia trachomatis – typically clear discharge
Mycoplasma hominis – typically clear discharge
Neisseria gonorrhoeae – typically purulent discharge
Ureaplasma urealyticum – typically clear discharge
***In sexually active men, purulent discharge is highly suggestive of gonorrhea
What diagnostic tests confirm Gonorrhea?
Gram Stain: Gm (-) diplococci intracellular bacteria
Can also do DNA probes for PCR or ELISA, but less common clinically
Neisseria gonorrhoeae classification
Bacteria
Gram (-)
Diplococci
Oxidase (+)
Only Glucose Oxidizer
What virulence factors help N. gonorrhoeae cause infection?
Specialized pili – allows attachment to mucosal surface, antigenic variation to evade host defenses, prevents killing by phagocytosis.
Endotoxin.
Capsule.
IgA protease.
What is the treatment for N. gonorrhoeae?
ceftriaxone (+ doxycycline for probable concurrent Chlamydia infections)
Prophylactic erythromycin eye drops for neonates.
Vaccine development difficult.
What unique culture does N. gonorrhoeae grow on?
Thayer-Martin media:
Media inhibits the growth of most other microorganisms.
Contains the following antibiotics: Vancomycin – kills most G (+) Colistin – kills most G (-) Nystatin – kills most fungi SXT – inhibits G (-) organisms, particularly swarming Proteus
Nutrients = chocolate sheep’s blood, beef infusion, casein hydrolysate, and starch.
How do you differentiate between N. gonorrhoeae and N. meningiditis?
N. meningitidis oxidizes both maltose and glucose.
N. gonorrhoeae only oxidizes glucose.
What is the clinical presentation of and N. gonorrhoeae Local infection (genital tract or anorectal infections)?
asymptomatic, urethritis, dysuria (men), cervicitis (women), opthalmia neonatorum (eye infections caused to exposure to the pathogen during birth).
What is the clinical presentation of and N. gonorrhoeae systemic infection?
septic arthritis
What are the complications of N. gonorrhoeae if left untreated?
Pelvic inflammatory disease (PID), ectopic pregnancy, sterility, Fitz-Hugh-Curtis Syndrome
In women, the infection can progress to the uterus, fallopian tubes, ovaries (PID) which can lead to an increased risk for ectopic pregnancies. From the fallopian tubes the bacteria can spill into the peritoneal cavity causing peritonitis. This can lead to an infection of the liver capsule (Fitz-Hugh-Curtis Syndrome).
In neonates, it can inoculate the conjunctiva during passage through the birth canal causing opthalmia neonatorum risk for blindness.