Week 1 - Day 2 notes
Terms
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- Lactose fermenters convert lactose into what 2 things? Name g- bacteria that are lactose fermentors?
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1. Acid and gas
2. E.Coli, Klebsiella, Enterobacter - What is function producing H2S?
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1. Hydrolyze Urea
2. Liquefy gelatin
3. Decarboxylate specific amino acid - Name two growth media inhibit g+ and used to identify lac +/- bugs?
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1. EMB (Eosine Methylene Blue) - E.Coli is metallic green, other Lac + bac turn black
2. MacConkey agar - Lac + turn purple - Traveler's Diarrhea is caused by what bug?
- E.Coli (fecal-oral, contaminated water)
- Can you develop immunity to E.Coli diarrhea?
- Yes - that is why normally children, travellers and immunocomprised are affected.
- 1.Name the virulent strains of E.Coli? 2.Describe the characteristic of each?
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1. Enterotoxigenic E.Coli (ETEC)- heat labile & heat stable . Stool --> rice water like.
2.Enterohemmorrhagic E.Coli(EHEC)- Shiga like toxin-->inhibit 60S ribosome.bloody diarrhea,ab.cramp --> hemorrhagic colitis
3.Enteroinvasive E.Coli (EIEC)- invades epithelial cells, small amts shiga toxin.Results: Fever,WBC,bloody diarrhea
4. Hemolytic-Uremic Syndrome: anemia, low Plts, renal failure. E.Col 0157:H7. Burgers. - With various virulent strains of E.Coli, E-Coli shares similarities between two bugs?
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1. Vibrio Cholera:watery diarrhea
2. Shigella: bloody diarrhea - Other than diarrhea, what are other clinical presentation of E.coli?
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1. UTI- most common cause. Cystitis, pyelonephritis
2. Meningitis - 2ndcommon.Neonates esp in 1st mth.
3. Sepsis - most common g-sepsis. nosocomial
4. Pneumonia - nosocomial - If E.Coli the most common cause of g- sepsis - who is the 2nd most common?
- Klebsiella pneumoniae
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1.Name the patient population susceptible to Klebsiella pneumoniae pneumonia?
2. How can you charaterize this pneumonia? -
1. ETOH and Debilitating patients
2. 50% bloody sputum,
The infection is violent, destroy lung tissue-->cavities - Sputum color and texture in Klebsiella pneumoniae pneumonia infection?
- Look like Red currant Jelly (color of the O antigen)
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1.Proteus Mirabilis motile or non-motile?
2. What does it usually cause?
3.The strains cross react with what other bug? -
1. g- motile
2. UTI, other nosocomial Infections
3.Rickettsia - Why is the urine alkaline with a Proteus Mirabilis infection?
- Splits Urea into NH3 and CO2
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1.Enterobacter motile or non-motile?
2. What is its setting for infection? -
1.g-lac+ motile, GI normal flora
2. Nosocomial (usually) - Serratia is notable for what?
- its Bright red pigment. (can cause UTI,wound,pneumonia)
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1.What are the hosts for Shigella?
2.Describe the shigella bug?
A. What are the host of Salmonella
B. Describe the Salmonella bug -
1.Humans
2. g-lac-H2S-oxidase- non-motile,invasive
A. Fish, Poultry(chickens and uncooked eggs, Humans (S.Typhi just in humans)
B. g-lac-H2S+oxidase- motile, Vi antigen (capsule)
[Vi -virulence] - Are Shigella and Salmonella part of the normal GI flora?
- Absolutely NOT. They are always pathogens
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1.What is the main toxin of shigella and what is its mechanism?
2.What other bugs use this toxin? -
1. Shiga toxin. Inhibits 60S ribsome (visualize shazam shigella blasting in the epithelial cell -60S protein)
2. EHEC and EIEC
enterohemmorrhagic e.coli and enteroinvasive e.coli - Route of transmission of shigella?
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1.Nasty people who dont wash their hands.
2. Fecal-Oral
3. Preschool children and Nursing home - Name the 3 types of salmonella? The 4 disease states in humans?
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1. S. cholerae-suis, S.typhi, S.enteriditis
2. a.Typhoid fever
b. carrier state (gallbladder)
c. Sepsis
d. Gastroenteritis (diarrhea) - Who is more invasive shigella or salmonella or Enteroinvasive E.coli?
- 1. Salmonella: Invades an exta step beyond GI epithelial cells --> to regional lymph nodes -->can seed organs/also get phagocytosized by macrophages
- What causes Typhoid fever? Describe the clinical presentation?
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1.Salmonella infection
2. Fever, rose Spots on abdomen , RLQ pain (like appendicitis), inflammation of organs, diarrhea - Treatment of Typhoid fever (Salmonella)?
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1. Ciprofloxacin
2. Ceftriaxone - Asymmptomatic carriers of salmonella have the bug residing in what organ?
- Gallbladder
- What Salmonella bug normally cause systemic dissemination in the blood? What organs are affected?
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1. S. Chlorea suis
2. Bone, Brain and Lung (remember pic with salmon swimming in blood) - Why are Sickle patient prone to Salmonella Osteomyelitis?
- Salmonella is encapulated with the Vi antigen and Sickle patient usually are asplenic.
- Which is more common diarrhea from Salmonella enteriditis or typhoid fever from Salmonella typhi?
- 1. Salmonella enteriditis
- Yersina entercolitica are acquired from fleas or fecal oral?
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1.Fecal oral. (another micmicker of appendicitis). Fever,diarrhea, ab pain
Yersina pestis is from flea - bubonic plaque - Name bacterial infections that micmick appendicitis in terms of location? RLQ
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1. Salmonella
2. Yersina enterocolita -
1.Name the 2 obligate intracellular g- bacteria?
2. Why? -
1.Chlamydia and Rickettsia
2. Can't produce their own ATP - How are Chlamydia and Rickettsia cultured?
- Living cells - Chick embryo yolk sac or cell culture
- How would you describe the sizes of Chlamydia and Rickettsia?
- 1. Very small. about 350nm which is the size of the big end of viruses
- What is the difference in transmission of Chlamydia and Rickettsia?
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1. Chlamydia is person to person
2. Rickettsia spread by an anthropod vector (e.g Tick) - Chlamydia has a peptidoglycan layer and muramic acid? T/F
- False - it has neither. But sure has an outer and inner layer. Still makes it g- bac
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What are the clinical presentations of Chlamydia?
What type of cells does it has preference to? -
1. Conjunctivitis, cervicitis, and pneumonia
2. Columnar epithelial cells -
1. Name the two stages of Chylamydia life cycle and describe?
2. What is the significance of each stage? -
1. Elementary body (EB) (inert,dense round,infectious particle,forms IB)
2. Initial body (reticulate body) - (metabolic, Dividing/Replicating DNA/RNA, forms EB) - Name the three species of Chlamydia and tissue they infect? What are all Tx with?
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1. Chlamydia trachomatis -Eyes,genitals and lungs
2. C. Psittaci- lungs
3. C. Pneumonia -Lungs
Tx: Tetracycline and Erythromycin - What is the leading cause of preventable blindness in the world?(according to CMBmadeSimple)
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Trachoma (caused by Chlamydia Trachomatis)
That is why all babies get erythromycin drops. - How does Trachoma cause blindness?
- The conjuctival infection by C. trachomatis causes scaring -->folds eyelids and they scar the conjuctiva and cornea --> secondary bacterial infections--> progress to blindness (all this within 10-15yrs)
- Why would penicillin therapy fail with Chylamydia?
- Chylamydia does not have a peptidoglycan layer! fool
- So if a pregnant mother has genital Chlamydia infection, what is the newborn at risk for?
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1. Conjunctivitis (purulent yellow discharge and swollen eyelids)
2.Infant pneumonia (diagnosis with IgM to chlmydia) - Gonorrhea is one cause of urethrits - what are other bugs that can cause urethritis? Tx?
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1. Chlamydia (can co-infect with Gonorrhea)
2. Ureaplasma urealyticum
for both Tx: azithromycin
for Gono: Ceftriaxone - The F1, V, and W virulence factors allow this organism to evade destruction after phagocytosis.
- Y. pestis
- How does Y. pestis stain on Gram?
- safety pin pattern
- Name that disease
- Nodes swell like eggs & become hot, red painful; hemorrhages under skin cause blackish discoloration
- Bubonic plague
- Pt recently hunted wild rabbit. Well demarcated ulcer with black base. Fever; nodes swollen, red, painful, sometimes draining pus. Included in DDx of bubonic plague
- Francisella tularensis
- fever, loss of appetite, back and head ache, sometimes lymphadenopathy. Undulant fever, peaking in evening and returns to normal by morning. Pt is a cattle rancher and presents with these symptoms which have lasted 2 months.
- brucellosis
- Gram negative zoonotic organism from cat and dog bites.
- Pasteurella multocida
- What can happen when a bacterial meningitis is treated with antibiotics. Steroid tx before antibiotic tx can be beneficial.
- Killed bacteria lyse and antigens (lipid A of LPS) is exposed --> immune response further damages neurons.
- Most common cause of septic arthritis in infants.
- H. flu
- What type of arthritis presents when H. flu is the cause? What other symptoms are present?
- monoarticular, fever, pain, swelling, decreased mobility
- What is added to the H. flu vaccine (H.flu type b capsule) that activates T cells and antibodies against the b capsule?
- diptheria toxin
- Haemophilus ducreyi causes -------. The DDx of this condition includes syphilis, herpes, and lymphogranuloma venereum.
- Chancroid. Painful genital ulcer with unilateral painful swollen inguinal lymph nodes. (syphilis = painless. Herpes = painful. LGV = painless)
- Bacterial vaginitis in which clue cells are found. What is the organism?
- Gardnerella vaginalis
- Treatment for Gardnerella vaginalis
- metronidazole (covers coinfecting anaerobes)
- Requires X factor and V factor for growth in culture.
- Hemophilus influenzae
- Organism that uses filamentous hemagglutinin to attach to epithelial cells of the bronchi.
- Bordetella pertussis
- Three stages of whooping cough
- catarrhal, paroxysmal (lasting months), convalescent
- B. pertussis secretes its own invasive ------- which enters mammalian cells (Bacillus anthracis produces a similar enzyme, EF). This toxin acts locally to reduce phagocytic activity and probably helps the organism initiate infection.
- adenylate cyclase (AC)
- Pertussis toxin permanently disables ------ by ADP ---------.
- Gi by ADP ribosylation
- Cause of Pontiac Fever
- Legionella pneumophila