Spirochetes, Chlamydia, Rickettsia Flashcards
Describe Leptospira (mode of transmission, clinical features, prevalence)
Dogs, Raccoons and rats are sources of indirect infection for humans. Can also be acquired by wading in contaminated water to enter via membranes/skin. Hepatic and renal dysfunction. Outbreaks can occur after tropical storms and via rat urine.
Describe Treponema pallidum (transmission, clinical features, progression)
Cause of Syphillis resulting in primary and secondary lesions that are rich in spirochete.
Any contact via birth, kissing, sexual contact or blood can be infective. Can progress into secondary or latent syphillis affecting the CV vessels and brain (aortic necrosis and mental retardation).
How can congenital syphillis present?
As developmental abnormalities that include notched teeth, saber shins, saddle nose, large liver/ spleen and secondary lesions on feet or in the face.
Why is Syphilis on the rise in the US (according to the CDC)?
Increased sharply with risky sexual behavior amongst gay or bisexual men. This is even increasing amongst heterosexual men which is thought to be increased with dating apps. There’s also a rise in syphilis in newborns.
Briefly describe the 3 methods of lab diagnosis to detect syphilis.
- Dark-field microscopy - T. Pallidum can be detected from exudate of primary and secondary lesions
- Nontreponemal tests - use of cardiolipin from mammalian tissue as the Ag along with lecithin and cholesterol to react with syphilitic reagin. This results in flocculation.
Describe at least 3 features of Chlamydia.
- Obligate intracellular parasites
- Extracellular form is spore-like
- Cannot synthesize ATP without host cell
Briefly describe the Chlamydia Developmental Cycle in 4 steps.
- Elementary body (EB) is phagocytosis into cell.
- Migrate to area around nucleus and reorganize as reticulate bodies (RB).
- RBs multiply into large cytoplasmic inclusions.
- Cell ruptures and EBs are released to infect neighboring cells.
What are some diseases that Chlamydia trachomatis cause? Describe the significance of one of them.
Ocular trachoma (disease of antiquity) and Genital tract infection (recently established in 19th century). Ocular trachoma is a common cause of preventable blindness and Chlamydia is the most common cause of STD in the US.
Describe the STD clinical manifestations of Chlamydia.
Mild or absent symptoms present in males or females (predominantly in the 20-25 age range). Increased risk of ectopic pregnancy. Common symptoms include swollen uterine tube, scarring and inflammation of the GI tract.
What is the type of laboratory diagnosis for Chlamydia?
PCR-based tests from vaginal swab in women or urine in men. This can also test for cervical cancer with ThinPrep endocervical specimen.
Briefly describe 3 features of Chlamydia pneumonia.
- This most common cause of human infection out of the 3 Chlamydia species.
- Common in children ages 5-14.
- Associated with mild upper respiratory tract infections, pneumonia or bronchitis.
Briefly describe 2 features of Chlamydia psittaci.
- Zoonosis contracted via inhalation of respiratory secretions from infected bird droppings
- Cause of mild to severe pneumonia, in which cough presents only in late-stage of the disease.
All species of Rickettsia, except Coxiella, are transmitted to human by _____________.
Arthropod vectors such as fleas, lice, mites and ticks.
Rickettsia Coxiella burnetii is a zoonosis in which what animals are the primary reservoirs?
Sheep, goats and cattle.
Compare and contrast Rickettsia from Chlamydia.
- Rickettsia targets mostly endothelial cells that line blood vessels, resulting in a hallmark rash.
- Chlamydia targets columnar epithelial cells that line mucous membranes to cause conjunctivitis,cervicitis and pneumonia.
