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33 Cards in this Set
- Front
- Back
What are the general characteristics of the Pseudomonadaceae family
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Aerobic, gram negative; do not ferment glucose; oxidase positive; polar flagellum
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What are the general characteristics of Pseudomonas aeruginosa
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Grape like odor; fluorescent green pigment; Ubiquitous in nature, commonly found in moist environments; Aggregates into biofilms and is resistant to many disinfectants and preservatives
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What diseases are caused by Pseudomonas aeruginosa
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A variety of infections, usually nosocomial. It is particularly virulent once established (highest gram-negative mortality)
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What increases the risks of Pseudomonas aeruginosa infection
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Impaired host defenses, such as: Disruption of skin, mucus membranes; Colonization of intravenous or urinary catheters; Compromised patients; Miscellaneous (external otitis)
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80-90% of Cystic fibrosis patients develop what type of infection
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Chronic Pseudomonas aeruginosa lung infections. Colonization increases with age
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What is the pathogenesis of Pseudomonas aeruginosa
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Ps. aeruginosa is a very virulent organism due to its capacity to invade deep within tissue and the action of its many toxins. Systemic disease can result, or LPS can cause fatal sepsis (fever, shock, DIC)
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What are the virulence factors of Pseudomonas aeruginosa
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Pili; Alginate capsule; pyocyanin; Exotoxins A and S; Extracellular proteases; Hemolysin; Endotoxin (LPS); Flagella with twitching motility
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What do exotoxin A and S found in Ps. aeruginosa do
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Exotoxin A is a potent inhibitor of mammalian protein synthesis. It and diphtheria toxin cause ADP ribosylation of EF-2
Exotoxin S also inhibits protein synthesis through ADP riboslyation, but the target is unknown |
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What does pyocyanin found in Ps. aeruginosa do
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Impairs cilia; damages tissue via production of O2 radicals
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What is twitching motility found in Ps aeruginosa
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Occurs via retraction and extension of the pseudomonas pili. Necessary for biofilm formation on plastic
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What is the treatment for Pseudomonas aeruginosa
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Single drug therapy should be avoided because of quick drug resistance. Recommend penicillin plus an aminoglycoside
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What type of infections is Acinetobacter baumanni known for
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Nosocomial infections. Dramatic increase in recent years, particularly bacteremia and pneumonia. Not particularly virulent, but frequently multidrug resistant
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High numbers of infections in soldiers in Iraq are caused by what
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Acinetobacter baumanni
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What are the 4 types of Urinary tract infections
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Ascending (most common); Hematogenous (Salmonella sp, Staphylococcus aureus, Candida sp); Uncomplicated (healthy people, 80% E coli); complicated (catheterized patients, immunosuppressed; wider spectrum of causative agents; Proteus mirabilis)
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What is the pathogenesis of Uropathogenic E coli
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Has virulence factors on pathogenicity islands encoding P fimbriae adhesins (adhere to P group) and Hemolysins; Type 1 fimbriae
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What is the pathogenesis of Proteus mirabilis (Enterobactericeae) in Urinary tract infections
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Demonstrates swarming motility due to lateral flagella. Predilection for the upper urinary tract. Associated with kidney stone formation due to the action of urease
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Besides Proteus mirabilis, what other gram negative rods cause complicated urinary tract infections
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Pseudomonas aeruginosa; Enterobacter sp and Klebsiella pneumoniae (Enterobacteriaceae)
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What is the laboratory diagnosis for uncomplicated UTI
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Culture clean catch midstream urine. Presence of multiple organisms or low concentrations suggests contamination
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What is the laboratory diagnosis of UTI in catheterized patients
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Isolated bacteria concentrations of 10^2 to 10^4 per mL. Multiple species are likely
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What is the treatment for uncomplicated UTI
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Sulfonamides and trimethoprim
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What are two causes of Neonatal meningitis
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E coli K1 (greatest risk first 4 weeks of life)
Citrobacter freundii (not common, forms brain abscesses) |
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3% of bacterial pneumonia is caused by what
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Klebsiella pneumonia. Urease positive, lactose fermenter; non motile, encapsulated.
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Which gram negative enteric bacteria can cause wound infections
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Klebsiella pneumoniae, Proteus sp., Ps. aeruginosa
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What is the leading cause of bacteremia in adults
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E coli. High incidence of nosocomial infections
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What are the characteristics of the onset of sepsis
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Often insidious- Fever, mental confusion, transient hypotension, oliguria, thrombocytopenia
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What is the epidemiology of sepsis
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750,000 US cases. 30% mortality rate, 40% in elderly, 50% if septic shock begins
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What are the clinical signs of gram-negative sepsis in response to
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Endotoxin (lipid A of the LPS)
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When does continuous septicemia occur
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Occurs primarily in patients with intravascular infections; occurs with septic shock. Blood culture will be positive
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When does intermittent septicemia occur
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In patients with infections at a distal site. Blood cultures may not be positive
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What are six of the most common gram negatative enteric bacilli that cause sepsis
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E. coli, Klebsiella sp., Enterobacter sp., Proteus sp., Serratia marcescens, P. aeruginosa
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What two Enterobacteriaceae are frequent contaminants of parenteral fluids
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Enterobacter sp and Serratia marcescens
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What three gram negative enteric bacilli are associated with transfusion sepsis
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Salmonella sp, Yersinia enterocolitica, Campylobacter sp.
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What is gram negative shock a response to
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Entodoxin-induced release of TNF-alpha by macrophages in the liver, spleen, and other body sites
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