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98 Cards in this Set
- Front
- Back
What is the MacConkey medium used for?
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Testing for lactose fermentation
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What color is the MacConkey medium? What color does it turn in the presences of lactose fermenetation? Why?
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Yellow. Red. due to the low pH.
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What is DNA hybridization used for?
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to determine the genetic distance between two speciies
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What are the gram-negative bacilli surface antigens?
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O antigen, H antigen, K antigen
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What is the O antigen?
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the somatic antigen; polysaccharide side chains of LPS
smooth- strains with side chains rough - strains with no side chains |
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What is the H antigen?
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flagellar antigen
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What is the K antigen
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capsular antigen
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What are the virulence mechanisms of gram-negative bacilli?
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adhesion/colonization, exotoxins, endotoxins, capsules, siderophores, antigenic variation, antimicrobial resistance
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What is used for adhesion/colonization?
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pili/fimbrae
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What are exotoxins?
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toxins excreted by microorganisms
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What are endotoxins?
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toxins that are structural molecules of the bacteria
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What are capsules?
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evasion of complement-mediated lysis
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What are siderophores?
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high affinity iron chelating compounds secreted by certain bacteria
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What is antigenic variation?
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alteration of surface proteins to evade host immune response
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How do bacteria display antimicrobial resistance?
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permeability changes, efflux pumps, resistance enzymes
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What are the major genera of the Enterobacteriaceae family?
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Enterobacter, Escherichia, Klebsiella, Proteus, Serratia, Yersinia
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What is the metabolic requirement for Enterobacteriaceae?
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facultative anaerobes
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Do enterobacteriaceae form spores?
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no
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What are some biochemical indicators of enterobacteriaceae?
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ferment glucose to acid and gas, reduce nitrate to nitrite, catalase positive, oxidase negative, resistant to bile salts, lactose or non-lactose fermenting
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Where are enterobacteriaceae species found in the environment?
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widely distributed in soil and water
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Where are enterobacteriaceae species normally found in human microflora?
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occaisonally in oropharyngeal flora, normally in the gi tract, frequently part of the vaginal flora
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90% of enterobacteriaceae isolates are which 3 species?
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escherichia coli, klebsiella pneumoniae, proteus mirabilis
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What are common enterobacteriaceae clinical syndromes?
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urinary tract, gastroenteritis, pneumonia, bone and soft tissue, meningitis, intra-abdominal (peritonitis, abscess), biliary tract, female pelvis
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Where is e coli found as part of microflora?
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human intestines
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What infections can e coli cause?
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UTI, meningitis, neonatal meningitis, enterotoxin production
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Intestinal disease due to e coli is more common in developing or developed areas?
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developing
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Extraintestinal disease due to e coli is more common in developing or developed areas?
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developed
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What is the appearance of Klebsiella on culture plates?
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mucoid appearnce' thick polysaccharide capsule, 70 antigenic variations, inhibits phagocytosis
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What antibiotic resistant genes do Klebsiella organisms express and where are they located?
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chromosomal genes encode beta-lactamase; plasmid-mediated extended spectrum beta-lactamases
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What causes rhinoscleroma?
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Klebsiella rhinoscleromatis
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What gives proteus organisms their high motility?
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they are highly elongated rods with thousands of flagellae
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How does proteus cause disease in the kidney?
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produce urease -> convert urea to co2 and nh3 -> urine ph increases -> causes precipitation of struvite and formation of stones (staghorn calculi)
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To what antibiotic is proteus mirabilis usually sensitive?
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ampicillin
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What pigment do many strains of serratia produce and what color is it?
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prodigiosin, red
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To what does serratis show resistance?
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disinfectants and non-bacterial soaps
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Is serratia found more often in the environment or as part of normal flora?
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environment
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Which three species of enterobacter are responsible for the majority of infections?
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E cloacae, E aerogens, E sakazakii
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Is enterobacter mostly nosocmial or CAS?
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nosocomial
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Is enterobacter a lactose fermenter? motile? mucoid?
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yes, yes, and yes
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What is the most common infection in patients on antibiotics and in the intensive care unit?
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enterobacter infections
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What antibiotic resistant genes does enterobacter have?
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inducible chromosomal beta-lactamase
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Describe Yersinia by its straining and biochem properties?
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gram-negative, bipolar staining, non-lactose fermenting
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What is the optimal growth temperature for Yersinia? What is the lowest growth temperature for Yersinia?
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28 C, 4 C
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To what defense in the body is yersinia resistant?
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serum complement
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What disease is caused by yersinia pestis?
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the plague
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What disease is caused by Yersinia enterocolitica?
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enterocolitis, mesenteric adentitis (mimics appendicitis), septicemia
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What increases the risk of infection by tersinia enterocolitica? Why?
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Fe overload (ex. hemolytic anemia) and Fe chelators; no siderophore
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What is associated with outbreaks of Yersinia enterocolitica?
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contamination at cold temperatures (ex. banked blood, chocolate milk, ice cream)
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Describe acinetobacter.
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aerobic gram-negative bacillus; coccocbacillary on gram stain, rod shaped on rapid growth
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Is acinetobacter nosocomial or CAS?
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both
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what is the most common infection due to acinetobacter?
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resp tract infections; LRTI w/dimished host defense, nosocomial pneumonia
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Aside from LTRI, what are other infections associated with acinetobacter?
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bacteremia, genitourinary, soft-tissue
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How do Halphilic vibrios appear under the microscope?
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curved, gram negative bacilli w/ single polar flagellum, erratic movement
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On what medium can halophilic vibrios grow?
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3% NaCl
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With what illness is Vibrio parahaemolyticus associated?
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diarrheal pathogen associated with seafood, common in Japan
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V vulnificus can be contracted after exposure to what?
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brackish or salt water, shellfish
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What clinical symptoms does v vulnificus cause?
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rapidly progressive cellul;itis with bacteremia (esp with cirrhosis)
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What symptoms are seen after Halophilic Vibrios infectino?
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abrupt onset fever, chills, hypotension (33%), metastatic skin lesions (75%)
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What is caused by v alginolyticus?
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cellulitis, acute otitis media and otitis externa after seawater contact, rarely bacetremia
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How is aeromas contracted?
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exposure to brackish/freshwater
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What is caused by aeromonas hydrophilia?
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soft tissue infections which ulcerate, bacteremia (60% of cases)
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What does aeromonas sobria cause?
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soft tissue infections, bacteremia, and septic shock
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Describe pasteurella multocida?
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gram-negative, non-motile, coccobacillus
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From where can pasteurella multocida be isolated?
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the nasopharynx and GI tract of domestic and wild animals and birds
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What infection does pasteurella multocida cause?
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focal soft tissue infections with an acute onset; erythema, pain, swelling
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Describe brucellosis.
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small aerobic, nonsporulating, gram-negative coccobacilli
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How is brucellosis transmitted?
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animal to human; abattoir workers, veterinarians at risk, associated with ingestion of unpasteurized dairy products, entry through abrasions in skin from infected carcasses, inhalation from aborting animals
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What is the pathogenesis of brucellosis?
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multiply in lymph nodes -> disseminate -> localize in liver, spleen, kidney
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In what cell does Brucellosis multiply?
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inside macrophages as a facultative intracellular parasite
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How is a brucellosis infection controlled by the body?
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through cell mediated immunity
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What can brucellosis cause to form in tissues?
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granulomas
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What are the clinical manifestations of an acute brucellosis infection?
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high fever, sweats, malaise, headache, anorexia, abdominal pain, diarrhea, back pain, lymphadenopathy (10%), hepatosplenomegaly (40%)
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What is the incubation period for a brucellosis infection?
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2-8 weeks
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What is the threatment for Brucellosis?
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prolonged (6 week) course of antibiotics
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What are the complciations of brucellosis?
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arthritis, osteomyelitis, meningitis
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Describe bartonella.
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intracellular, gram-negative pathogens
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What are diseases associated with bartonella?
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acute febrile bacteremia, persistent asymptomatic bacteremia, indolent vascular skin infections
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How long does it take to grow bartonella in culture?
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several weeks
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How can bartonella be seen in tissues?
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silver stain
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What is the disease caused by Bartonella bacilliformis called?
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oroya fever, carrion's disease
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Where is bartonella bacilliformis seen?
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andes: peru, ecuador, colombia
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How is bartonella bacilliformis transmitted?
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by sandfly
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In which cells do bartonella bacilliformis live?
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RBCs
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What are the symptoms of the acute bacteremic phase of b bacilliformis?
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fever, myalgias, arthralgias, headache (40% mortality if not treated)
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What are the symptoms of the chronic phase of b bacilliformis?
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verruga peruana (cutaneous nodules) after 1-2 months which may persist for years
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What is infection caused by bartonella henselae called?
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cat scratch disease
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How is infection by bartonella henselae transmitted?
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cat flea
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What is the incubation period for bartonella henselae?
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3 weeks
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How does someone with bartonella henselae present?
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enlarged, tender lymph nodes (granulomas with central necrosis and giant cells present); fever, malaise, local papulae may be present
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What is the most common cause of regional lymphadenitis in kids?
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bartonella henselae
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What does bartonella quintana cause?
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trench fever
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How is bartonella quintana transmitted?
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body louse feces
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What is the incubation time for bartonella quintana?
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3-38 days
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What are the symptoms of bartonella quintana?
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fever, headache, rash, splenomegaly; bacteremia and endocarditis reported among homeless people and alcoholics
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What is the cause of culture negative endocarditis?
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bartonella quintana
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What can cause bacillary angiomatosis?
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bartonella henselae and bartonella quintana
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In which patients is bacillary angiomatosis seen?
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immunocomprimised HIV+ patients with CD4 < 100
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What can cause peliosis hepatis?
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bartonella henselae
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