Bacteriology - Basics Flashcards
Which cell membrane structure is unique to gram-positive organisms?
Teichoic acid
Which molecule, unique to the bacterial cell wall, provides rigid support and resistance against osmotic pressure?
Peptidoglycan
Which heat-stable lipopolysaccharide (LPS) is found in the cell wall of gram-negative bacteria?
Endotoxin
Which is the only gram-positive organism with LPS-lipid A?
Listeria monocytogenes
Name five important systemic effects of endotoxin (particularly, lipid A):
- ↑Interleukin (IL)-1 → fever
- ↑ Tissue necrosis factor (TNF) → hemorrhagic tissue death
- ↑ Nitric oxide → hypotension and shock
- Activation of alternate complement pathway →↑ C3a (edema) and C5a (polymorphonuclear [PMN] chemotaxis)
- Activation of factor XII → coagulation cascade → DIC
Which has a higher toxicity, endotoxins or exotoxins?
Exotoxins: fatal dose on the order of 1 μg (vs hundreds of micrograms for endotoxins)
Name the mechanism of DNA transfer characterized by the following statements:
DNA is taken up directly from the environment by competent cells
Transformation (can occur in eukaryotic cells, too) Medically important natural transformers: HHSNG: “Here, Have Some New Genes”: H. pylori, H. influenzae, S. pneumoniae, N. gonorrhoea
Name the mechanism of DNA transfer characterized by the following statements:
Plasmid or chromosomal DNA transferred from one bacterium to another via cell-to-cell contact
Conjugation
Name the mechanism of DNA transfer characterized by the following statements:
DNA transferred by a virus from one cell to another; can be generalized or specialized
Transduction
Name the mechanism of DNA transfer characterized by the following statements:
DNA segments able to excise and reincorporate into different locations
Transposons
Name the bacterium whose exotoxin has the following effects:
Superantigen that induces IL-1 and IL-2 synthesis in toxic shock syndrome; also leads to food poisoning
Staphylococcus aureus
Name the bacterium whose exotoxin has the following effects:
α-Toxin is a lecithinase → gas gangrene
Clostridium perfringens
Name the bacterium whose exotoxin has the following effects:
Prevents the release of the neurotransmitter (NT) glycine from Renshaw cells in spinal cord → paralysis
Clostridium tetani
Name the bacterium whose exotoxin has the following effects:
↑ Adenylate cyclase by adenosine diphosphate (ADP) ribosylation → whooping cough
Bordetella pertussis
Name the bacterium whose exotoxin has the following effects:
Exotoxin encoded by β-prophage; α subunit → inactivates elongation factor 2 (EF-2) halting protein synthesis; β subunit → permits entry into cardiac and neural tissue
Corynebacterium diphtherias
Name the bacterium whose exotoxin has the following effects:
Erythrogenic superantigen → rash in scarlet fever
Streptococcus pyogenes
Name the bacterium whose exotoxin has the following effects:
Prevents release of acetylcholine (ACh) → central nervous system (CNS) paralysis; spores in canned food and honey, construction sites
Clostridium botulinum
Name the bacterium whose exotoxin has the following effects:
Heat-stable toxin ↑ guanylate cyclase; heat-labile toxin ↑ adenylate cyclase by ADP ribosylation of G protein → watery diarrhea
Escherichia coli
Name the bacterium whose exotoxin has the following effects:
Inactivates the 60S ribosome → kills intestinal cells
Shigella dysenteriae
Name the bacterium whose exotoxin has the following effects:
Permanent ADP ribosylation of G protein →↑ adenylate cyclase →↑ Cl- and H2OO in gut → voluminous stools
Vibrio cholerae
Name the bacterium whose exotoxin has the following effects:
Exotoxin A inhibits protein synthesis by blocking EF-2
Pseudomonas
Which virulence factor allows organisms to colonize mucosal surfaces?
IgA protease (eg, S. pneumoniae and H. influenzae)
Name the bacterial structure associated with each antigenic classification given below:
K-antigen
Capsule (related to virulence of the bacteria)
K = Kapsule
Name the bacterial structure associated with each antigenic classification given below:
O-antigen
Outer portion of the polysaccharide of endotoxin
O = Outer
Name the bacterial structure associated with each antigenic classification given below:
H-antigen
Flagella (seen in motile species)
Name the key virulence f actor(s) associated with each of the following organisms:
Group A streptococcus
M-protein, streptokinase, and hyaluronidase
Name the key virulence f actor(s) associated with each of the following organisms:
Staphylococcus aureus
Protein A (prevents complement fixation and phagocytosis), penicillinase, and hyaluronidase
Name the key virulence f actor(s) associated with each of the following organisms:
Streptococcus viridans
Extracellular dextran → helps bind to heart valves
Name the key virulence f actor(s) associated with each of the following organisms:
Yersinia pestis
F1 capsular antigen (antiphagocytic) and protease (degrades clots)
Name the key virulence f actor(s) associated with each of the following organisms:
Haemophilus influenzae
Capsule: six types (a-f) and IgA protease
Name the key virulence f actor(s) associated with each of the following organisms:
Borrelia
Antigenic variation
Name the key virulence f actor(s) associated with each of the following organisms:
Mycobacterium tuberculosis
Mycosides (cord factor, wax D, and sulfatides)
