Microbio Ch. 21 Notes PDF

Rickettsias group: - extremely small G- bacteria - obligate intracellular parasites - 4 genera cause disease in humans: Rickettsia, Orientia, Ehrlichia, and Anaplasma - Rickettsia genus: bacteria live in the cytosol of host cell after lysing the phagosome -...

Rickettsias group: - extremely small G- bacteria - obligate intracellular parasites - 4 genera cause disease in humans: Rickettsia, Orientia, Ehrlichia, and Anaplasma - Rickettsia genus: bacteria live in the cytosol of host cell after lysing the phagosome - R. rickettsii – rocky mountain spotted fever - spread by wood ticks; without early diagnosis, mortatlity rate is approximately 20%; prevention involves avoiding ticks - R. prowazekii – Epidemic typhus - causes high fever, depression, rash - occurs in crowded, unsanitary conditions - death in 60% of elderly patients, 20% in younger patients - Ehrlichia - both resemble Rocky Mountain spotted fever without the rash - lone star tick (Amblyoma) and deer tick (lxodes) transmit bacteria - triggers own phagocytosis Chlamydias: - once considered to be viruses - grow and multiple only within the vesicles of host cells - elementary bodies (EBs) dormant infective stage - reticulate bodies (RBs) noninfective obligate “adult” stage that replicates - Chlamydia trachomatis - enters the body through abrasions and lacterations - infects the conjunctiva and various mucous membranes - most common reportable STD in the US - usually asymptomatic in women, but associated with discharge and painful urination in both sexes  - reinfection leads to exaggerated response that can lead to blindness, sterility, or sexual dysfunction (PID) - Lymphogranuloma venereum: most infections in women are asymptomatic; reinfection may cause pelvic inflammatory disease - Trachoma: ocular disease; leading cause of nontraumatic blindness in humans; scarring of the conjunctiva causes the eyelashes to turn inward (causes corneal abrasions that lead to blindness); infection typically occurs during childbirth - prevention: abstinence to prevent STIs; blindness prevented with prompt use of antibacterial agents Sprichetes: - phylum spirochaetes - Treponema, Borrelia, and Leptospira - Treponema – Treponema pallidum pallidum: pathogen of humans only; syphilis - Syphilis: - primary stage: highly infectious - secondary stage: mucosal rashes; infectious - latent period: no symptoms, many infections stop here - tertiary stage: appears years after latency – 25% of people if untreated (due to cell-mediated immune reactions - congenital: transmits through the placenta; neurological damage to the fetus and stillbirth with first stage or second stage pregnancy - government funded research – Tuskegee study - Borrelia burgdorferi - Lyme disease – Borrelia burgdorferi is the causative agent – Lacks iron- containing enzymes and proteins and uses manganese to avoid the lack of iron in body - severe arthritis that can last for years; result of the body’s immune response  - humans in closer association with Borrelia-infected deer ticks Vibrio: - Vibrio cholerae: “rice-water stool” is characteristic - causes severe loss of fluid and electrolytes - can lose 3-5 gallons of fluid per day - causes shock, collapse, organ failure, and death (50% untreated) - Campylobacter jejuni: likely most common cause of gastroenteritis in the US (fever, cramping, abdominal pain, diarrhea, dysentery) - poultry is the most common source of infection - Helicobacter pylori: slightly helical, motile bacterium - causes gastritis and most peptic ulcers - demonstrated by positive urease test - prevention: good hygiene, adequate sewage treatment, proper food handling