Microbiology: Basic Bacteriology Flashcards
(170 cards)
What color pigment does Pseudomonas aeruginosa produce?
Blue-green (aeruginosa: arugula is green)
Coxiella is considered an obligate intracellular pathogen. Name other bacteria in this class.
Rickettsia, Chlamydia, &; COxiella are intracellular (stay inside [cells] when it is Really CHilly &; COld)
What component of the cell envelope extends from the membrane to the exterior and induces TNF-α and IL-1 on gram-positive bacteria?
Lipoteichoic acid (in gram positive) bacteria
Anaerobic bacteria usually smell bad, are difficult to culture, and produce CO2 and H2 in tissue. What causes the foul smell?
Short-chain fatty acids
When an anticoagulated tube of blood from a man with fever cools, precipitate forms. Mycoplasma pneumoniae is found. What medium was used?
Eaton agar; M pneumoniae requires cholesterol
Your microbiology lab advisor wishes to use a special silver stain. What organisms may he be looking for?
Legionella, Helicobacter pylori, and fungi (eg, Coccidioides, Pneumocystis jirovecii)
Exotoxins are typically destroyed at 60°C. What are the exceptions?
Staphylococcal enterotoxin and Esherichia coli heat-stable toxin are exceptions
In patients with pharyngitis, what protein from group A Streptococcus species prevents phagocytosis by the body’s immune cells?
M Protein
What type of toxin causes sepsis and meningococcemia?
Endotoxin
What bacteria usually utilize a type III secretion system?
Gram ⊖ bacteria such as Pseudomonas, Salmonella, Shigella, and Escherichia coli
What is the chemical composition of the bacterial cytoplasmic membrane, and what are the membrane’s 2 main enzymatic functions?
The membrane comprises a phospholipid bilayer with embedded proteins; its main enzymatic functions are oxidation and transportation
What component of the cell envelope induces TNF on gram-negative bacteria?
Lipid A (also induces IL-1)
IgA protease allows bacteria to colonize mucous membranes. Describe its mechanism of action.
IgA protease cleaves IgA, allowing bacteria to adhere to mucous membranes
What cell wall structures do gram ⊖ and gram ⊕ bacteria have in common?
Both gram ⊕ and gram ⊖ bacteria have flagella, pili, capsules, peptidoglycans, and cytoplasmic membranes
Catalase degrades H2O2, preventing conversion to microbicidal products by myeloperoxidase (enzyme). Name 7 catalase-⊕ organisms.
Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, Escherichia coli, Staphylococci, Serratia, Burkholderia cepacia, Helicobacter pylori (Cats Need PLACESS to Belch Hairballs)
What cheaper and sensitive stain is used in lieu of the Ziehl-Neelsen stain to screen for mycobacteria?
Auramine-rhodamine stain
When autoclaving surgical equipment, what temperature and time setting should be used to kill bacterial spores?
Equipment must be autoclaved for 15 minutes at 121°C because bacterial spores are highly resistant to heat and chemicals
A man with an Escherichia coli infection has significant fever, hypotension, and edema. What component of the bacteria is responsible for his symptoms?
Lipopolysaccharide (LPS) in the outer membrane of gram ⊖ bacteria (eg, E coli); activates macrophages, complement, and tissue factor
What is a type III secretion system?
A special protein appendage produced by gram ⊖ bacteria that allows direct delivery of toxins
A patient with scarlet fever has erythrogenic toxins in her blood. What toxin is to blame for her symptoms?
Exotoxin A, which causes toxic shock-like syndrome (rash, fever, shock) and is released by Streptococcus pyogenes
A man recovering from trauma has a foul-smelling, necrotic skin lesion with crepitus. Mechanism of action of the causative toxin?
The alpha toxin of Clostridium perfringens, a phospholipase, degrades phospholipids, causing tissue and cell membrane necrosis (myonecrosis)
A child with whooping cough has an infection with bacteria having which mechanism of virulence?
Bordetella pertussis toxin overactivates adenylate cyclase, disables Gi, and impairs phagocytosis, permitting survival of the microbe
In endotoxin-based complement activation, which complement(s) cause(s) hypotension/edema and histamine release?
C3a and C5a
Endotoxin activation of macrophages causes release of cytokines (IL-1, IL-6, TNF-α). What are their functions?
IL-1 and IL-6 cause fever; TNF-α causes both fever and hypotension