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microbiology some bug characteristics


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Stain used to diagnose Whipple's disease
PAS (Periodic Acid Schiff)
PAS stains ---
glycogen, mucopolysaccharides
Ziehl-Neelsen stains ---
Acid-fast bacteria
India ink stains ---
Cryptococcus neoformans
Congo red stains -- and exhibits ---
Amyloid, apple-green birefringence in polarized light
Giemsa's stains what 4 organisms?
Borrelia, Plasmodium, trypanosomes, Chlamydia (intracellular inclusions on Giemsa)
Conjugation, Transduction, Transformation: Which process can involve eukaryotic DNA?
Conjugation, Transduction, Transformation: DNA transferred from 1 bacterium to another through a sex pilus is
Conjugation, Transduction, Transformation: DNA transferred by a virus from 1 cell to another
Conjugation, Transduction, Transformation: Generalized transduction can transfer --
Any gene
Conjugation, Transduction, Transformation: Specialized transduction transfers ---
only certain genes (that's why it's special!)
Nagging Pests Must Breathe helps you remember what?
obligate aerobes: Nocardia, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Bacillus
Aerobic bacteria commonly found in burn wounds, nosocomial pneumonia, and pneumonias in cystic fibrosis patients?
Pseudomonas aeruginosa (an obligate aerobe)
What bug likes the lungs’ apices and why?
Mycobacterium tuberculosis – because the apices have the highest partial pressure of oxygen
If you hear crepitus, indicating gas in tissue, what type of infection do you suspect?
Anaerobic bacterial infection, such as Clostridium, Bacteroides, or Actinomyces (CBA)
Which bugs are anaerobic and why?
Clostridium, Bacteroides, and Actinomyces. Air causes them oxidative damage, because they lack catalase and/or superoxide dismutase.
Why are aminoglycoside antibiotics ineffective against anerobic bacteria?
AminO2glycosides require O2 to enter into bacterial cells; anaerobic bacteria aren't where the oxygen is
Name the 2 obligate intracellular organisms
Rickettsia, Chlamydia - "They stay inside (cells) when it's Really Cold"
Why do they need the host's cell?
They can't make ATP
Name 7 facultative intracellular organisms
Mycobacterium, Brucella, Francisella, Listeria, Yersinia, Legionella, Salmonella
List 4 examples of encapsulated bacteria
Streptococcus Pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Klebsiella pneumoniae
What is the main virulence factor of encapsulated bacteria and why?
Polysacharide capsule is antiphagocytic
What is a necessary component of humoral immune response to encaps. Bacteria?
What vaccines are available for encapsulated bacteria?
Pneumovax, H. influenzae, meningococcal
What serves as vaccine antigen?
What laboratory test can be used to detect the presence of encapsulated bacteria?
Quellung reaction - capsule swells when specific anticapsular antisera are added - "Quellung = capsular swellung"
What complications/clinical signs is pneumococcus associated with?
Rusty sputum, sepsis in sickle cell anemia, and splenectomy
What kind of bacteria form spores and when?
Certain gram-positive rods when nutrients are limited
Name 3 spore-formers
Bacillus anthracis, C. perfringens, C. tetani = gram positive soil bugs
T or F: Spores are highly resistant to destruction by heat and chemicals
Spores have ___ acid in their core
T or F: Spores are metabolically active
False. Spores have no metabolic activity
What disinfecting procedure kills spores?
Autoclaving (ex/ surgical equipment)
What organisms are alpha-hemolytic?
Pneumococci, viridans strep
Pneumococci are catalase ___ and optochin ___
Pneumococci are catalase negative and optochin sensitive
Viridans strep are catalase ___ and optochin ___
Viridans strep are catalase sensitive and optochin resistant
What organisms are beta-hemolytic?
Staph aureus, strep pyogenes, strep agalactiae, lysteria monocytogenes
Staph aureus is catalase ___ and coagulase ___
Positive, positive
Strep pyogenes is catalase ___ and bacitracin __
negative, sensitive
Strep agalactiae is catalase __ and bacitracin__
negative, resistant
Where is Lysteria monocytogenes found, and what is its characteristic pathology and laboratory appearance?
Unpausterized milk, miningitis in newborns, tumbling motility
What are catalase and coagulase tests used for?
Catalase is used to distinguish staph (+) from strep (-), coagulase is used to distinguish S. aureus (+) from S. epidermis (-) and S. saprophyticus(-)
How is catalase a virulence factor?
It degrades H2O2, an antimicrobial product of PMNs that is a substrate for myeloperoxidase
What is the function of protein A?
Virulence factor - binds to Fc-IgG and inhibits complement fixation and phagocytosis
TSST is a ___ (type of virulence factor) that binds to ___ (2 types of receptor) and causes ___ of ___ (type of cells) leading to ___ (disease)
TSST is a superantigen that binds to MHC II and T-cell receptor and causes polyclonal activation of T-cells leading to toxic shock syndrome
3 toxins of S. aureus and a syndrome caused by each
TSST- 1 - toxic shock syndrome, exfoliative toxin - scalded skin syndrome, enterotoxins - rapid-onset food poisoning
T/F - S. aureus causes acute bacterial endocarditis
T/F - S. aureus causes skin disease and organ abscesses, but not pneumonia
False - causes all 3
T/F - S. aureus food poisoning is due to bacterial infiltration of the intestinal wall
False - it is due to ingestion of preformed enterotoxin

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