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Week 1 - Day 2 notes


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Lactose fermenters convert lactose into what 2 things? Name g- bacteria that are lactose fermentors?
1. Acid and gas
2. E.Coli, Klebsiella, Enterobacter
What is function producing H2S?
1. Hydrolyze Urea
2. Liquefy gelatin
3. Decarboxylate specific amino acid
Name two growth media inhibit g+ and used to identify lac +/- bugs?
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?
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?
1. Vibrio Cholera:watery diarrhea
2. Shigella: bloody diarrhea
Other than diarrhea, what are other clinical presentation of E.coli?
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
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)
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
Why is the urine alkaline with a Proteus Mirabilis infection?
Splits Urea into NH3 and CO2
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)
1.What are the hosts for Shigella?
2.Describe the shigella bug?

A. What are the host of Salmonella
B. Describe the Salmonella bug
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
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?
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?
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?
1.Salmonella infection
2. Fever, rose Spots on abdomen , RLQ pain (like appendicitis), inflammation of organs, diarrhea
Treatment of Typhoid fever (Salmonella)?
1. Ciprofloxacin
2. Ceftriaxone
Asymmptomatic carriers of salmonella have the bug residing in what organ?
What Salmonella bug normally cause systemic dissemination in the blood? What organs are affected?
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?
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
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?
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
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?
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)
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?
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?
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.
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

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