Microbiology Flashcards
What is commensalism?
A type of symbiosis where one organism benefits, but the other is neither helped nor harmed
What is the difference between an abscess and a granuloma?
Abscess: acute inflammatory lesion of pus
Granuloma: chronic inflammatory lesion full of fibrosis, angiogenesis, and inflammatory cells
Which microorginisms most commonly cause sepsis?
Bacteria only!
Staph. aureus, Klebsiella sp., and E. coli
Cysts are filled with _______.
fluid or air
All bacteria except _________ contain a plasma membrane surrounded by a __________ cell wall.
Mycoplasma; peptidoglycan
What surrounds the cell wall in bacteria?
polysaccharide capsule
Which bacteria has a protein containing D-glutamate capsule instead of a polysaccharide capsule?
Bacillus anthracis
What are the three ways bacteria exchange genetic information?
Transformation: uptake from environment
Conjugation: sex with plasmid
Transduction: viral
What enzymes allow for evasion of host defenses?
Coagulase: promotes clot
IgA protease: Strep. pneumoniae, H. influenzae, Neisseria sp.
Leukocidins: destroy PMNs and macrophages
What virulence factor destroys plasma membranes and causes gangrene?
Lecithinase
What three virulence factors cause Beta-hemolysis?
Streptolysin O
Streptolysin S
Pneumolysin
__________ are found within the cell wall and are only associated with gram - bacteria and listeria.
Endotoxins
T/F: LPS is an example of an endotoxin.
True
Enterotoxins are an example of ________ that affect intestinal endothelial cells.
exotoxins
List the exotoxins which are classified as ADP-ribosylation and increase adenylate cyclase activity.
Cholera (V. cholerae)
Pertussis (B. pertussis)
Anthrax - edema factor (B. anthracis)
Heat-labile toxin (E. coli)
T/F: The Diphtheria toxin increases adenylate cyclase activity.
False
Inhibits protein synthesis
Which bacteria utilize superantigens?
Staph. aureus - TSST
Strep. pyogenes - erythrogenic toxin
Clostridium tetani and clostridium botulinum both utilize protease exotoxins which function as _________.
neurotoxins
What type of exotoxin is the anthrax lethal factor?
Protease - cleaves phosphokinase
What are the three modes of action for endotoxins?
- Activate macrophages
- Activates compliment
- Activates hageman factor
Bacilla are _____ shaped bacteria.
rod
Cocci are ______ shaped bacteria.
round
Which bacteria have a flexible thin cell wall?
Spirochetes
Which two bacteria are known to be obligate intracellular bacteria?
Rickettsia and Chlamydia
T/F: Mycobacteria have no cell wall.
FALSE
Mycoplasma: no cell wall
Mycobacteria: acid-fast extracellular bacteria
What are the cocci shaped gram - and gram + bacteria?
Gram - : Neisseria
Gram + : Strep, Staph
What do Bacillus and Clostridium species have in common?
Spore forming, gram + bacilli
What do Actinomyces, Listeria, and Corynebacterium have in common?
Non-spore forming, gram + bacilli
_________ is an aerobic, gram - bacilli.
Pseudomonas
What is an anaerobic gram - bacilli?
Bacteroides
What do Escherichia, Salmonella, and Helicobacter species all have in common?
Facultative gram - bacilli
What are the cell wall characteristics of a gram + bacteria?
Stains purple
Thick (+ size)
Lipoteichoic acid (LTA)
No endotoxin
What do obligate anaerobic bacteria lack that does not allow them to grow in oxygenated environments?
Superoxide dismutase and/or catalase
Streptococci grow in _______, while staphylococci grow in _______.
pairs/chain; grapelike clusters
Which streptococci are part of the normal flora of the mouth?
Viridans group: S. mutans and S. sanguis
Which strep can cause meningitis, otitis media, pneumonia, and sinusitis?
S. pneumoniae
T/F: S. pyogenes expresses alpha hemolysis.
False
Beta
T/F: Enterococci express gamma hemolysis.
True
What are the major virulence factors of Staph. aureus?
Protein A, beta-lactamase, enterotoxin
Causes abscess, pneumonia, toxic shock syndrome, food poisoning, MRSA, endocarditis, osteomyelitis
Which staph causes UTIs?
S. saprophyticus
What do Bacillus anthracis, Bacillus cereus, and Clostridium species all have in common?
Gram + spore-forming bacteria
T/F: Actinomyces israelii is a gram + spore forming bacteria.
False
Gram + non-spore-forming
Has sulfur granules and is part of normal oral flora
What do E. coli, Salmonella sp., Shigella sp., Vibrio cholerae, and H. pylori all have in common?
Gram - enteric bacilli
Which bacteria causes pink eye?
Haemophilus aegyptius
T/F: Mycoplasma pneumoniae causes true pneumoniae.
False
Walking pneumonia
What are the three stages of the disease caused by Borrelia burgdorferi?
Lyme disease
- Erythema migrains (bulls eye)
- Neuropathies (Bell’s palsy)
- Arthritis and CNS disease
Which organism is found most commonly on the surface of the tongue?
Strep. salivarius
What is the dominant bacterial species of supragingival plaque?
Gram + facultative cocci
Subgingival = gram - anaerobic bacilli and spirochetes
What is the epitactic concept?
Seeding agents (protein-carb complexes or bacteria) induce mineralization of calculus
Caraiogenic bacteria synthesize ________ and _______ from their metabolism of dietary ________.
glucans (dextrans) and fructans (levans); sucrose
Critical pH for for enamel is ____.
5.5
Gingivitis associated with sex steroid fluctuations is associated with elevated levels of which bacteria?
Prevotella intermedia
Which bacteria is often seen to be elevated in aggressive periodontitis?
A. a. and P. gingivalis
Elevated proportions of spirochetes in the mouth is associated with _____.
NUG/NUP
