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98 Cards in this Set

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