Basic Bacteriology Flashcards
What of part of the bacteria contains lipopolysaccharide (LPS)?
outer membrane (gram negative)
What contains a variety of genes for antibiotic resistance, enzymes, and toxins?
plasmid
What allows for adherence to surfaces, especially foreign surfaces?
glycocalyx
What microorganisms contain sterols and have no cell wall?
mycoplasma
What microorganisms contain mycelia acid and a high lipid content?
mycobacteria
What microorganisms are detected on Giemsa stain?
Chlamydiae (pleomorphic) Borrelia (spirochetes) Rickettsiae (pleomorphic) Trypanosomes Plasmodium
Certain Bugs Really Try my Patience
What microorganisms do not stain well?
These Microbes May Lack Real Color
Trepenoma Mycobacteria Mycoplasma Legionella Rickettsia Chlamydia
Which microorganisms are detected with periodic acid-Schiff (PAS)?
stains GLYCOGEN
Used to diagnose WHIPPLE DISEASE (Tropheryma whipplei)
PASs the sugar
Which microorganisms are detected with Ziehl-Neelsen (carbol fuchsin)?
acid-fast organisms (Nocardia, Mycobacterium)
Which microorganisms are detected with India ink?
Cryptococcus neoformans
Which microorganisms are detected with silver stain?
fungi (e.g. pneumocystis)LegionellaHelicobacter pylori
What is the special culture requirement?
- H. influenzae
- N. gonorrhoeae,
- B. pertussis
- C. diptheriae
- M. tuberculosis
- M. pneumoniae
- Lactose-fermenting enterics
- Legionella
- Fungi
- chocolate agar
- Thayer-Martin media
- Bordet-Gengou (potato) agar
- Tellurite agar, Loffler medium
- Lowenstein-Jensen agar
- Eaton agar, requires cholesterol
- Pink colonies on MacConkey agar
- charcoal yeast extract agar
- Sabouraud agar
What are examples of obligate aerobes?
Nagging Pests Must Breathe
Nocardia
Pseudomonas aeruginosa
MycoBacterium Tuberculosis
If someone uses an TNF - alpha inhibitor or is immunocompromised and gets a reactivation of TB, where will the infection most likely show in the lungs and why?
TB will have a predilection for the apices of the lung b/c it has the highest PO2
What are examples of obligate anaerobes?
Anaerobes Can’t Breathe Air
Clostridium
Bacteroides
Actinomyces
What are some defining features of obligate anaerobes?
generally foul smelling and produce gas in the tissue
Where are anaerobes normally found?
GI tract
What class of antibiotics is ineffective against anaerobes and why?
Aminoglycosides b/c these antibiotics require O2 to enter into bacterial cells
What are 2 obligate intracellular organisms?
Rickettsia
Chlamydia
What are examples of facultative intracellular organisms?
Some Nasty Bugs May Live FacultativeLY
Salmonella Neisseria Brucella Mycobacterium Listeria Francisella Legionella Yersinia pestis
What are examples of encapsulated bacteria?
SHiNE SKiS
Strep. pneumoniae H. influenzae Neisseria meningitidis E. coli Salmonella Klebsiella pneumoniae group B Strep
What are examples of catalase positive organisms?
You need PLACESS for your CATs.
Psuedomonas Listeria Aspergillus Candida E. coli S. aureus Serratia
CAT = catalase positive
Most encapsulated bacterial vaccines require what additional component in order for the polysaccharide capsule to be presented to the T cells?
the polysaccharide capsule Ags must be conjugated to a carrier protein
EXAMPLES: pneumococcal vaccine, H. influenzae type B, and meningococcal vaccine
EXCEPTION: penumococcal polysaccharide vaccine with no conjugated protein i.e. Pneumovax
What are urease-positive bugs?
CHuck norris hates PUNKSS
Cryptococcus H. pylori Proteus Ureaplasma Klebsiella S. epidermidis S. saprophyticus
What color pigment is associated with the following microbes…
Actinomyces israelii
S. aureus
Pseudomonas aeruginosa
Serratia marcescens
Actinomyces israelii - yellow “sulfur” granules
S. aureus - yellow pigment
Pseudomonas aeruginosa - blue/green pigment
Serratia marcescens - red pigment
What is the function of Protein A and which microorganism expresses it?
Binds Fc region of IgG –> prevents opsonization and phagocytosis
S. aureus
What is the function of IgA protease and which microorganisms express it?
enzyme that cleaves IgA
S. pneumoniae
H. influenzae type B
Neisseria
**They do this in order to colonize respiratory mucosa
What is the function of M protein and which microorganism expresses it?
helps prevent phagocytosis
expressed by group A strep
What is the mechanism of the diphtheria toxin?
ribosylation of EF-2 –> inhibits protein synthesis
What do the pseudomonas aeruginosa (exotoxin A) and the diphtheria toxin have in common?
both inactivate EF-2 –> inhibit protein synthesis
What is the similar mechanism of actin for Shiga toxin (ST) and shing-like toxin (SLT)?
inactivate 60S ribosome by removing adenine from rRNA
What is a major difference between Shigella and EHEC?
EHEC does NOT invade host cells
Hemolytic uremic syndrome (HUS) is more often seen in EHEC or Shigella infections?
EHEC
What are the 2 toxins secreted by enterotoxigenic E. coli (ETEC)?
- heat LABILE toxin (LT) –> over activates adenylate cyclase –> increases cAMP –> increases Cl secretion into gut and water efflux
- heat STABILE toxin (ST) –> over activates gauntlet cycle –> increases cGMP –> decreases resorption of NaCl and water in gut
What does the toxin in bacillus anthracis cause increased fluid secretion?
EDEMA FACTOR - mimics the adenylate cyclase enzyme –> increases cAMP
How does vibrio cholera’s toxin cause increased fluid secretion?
CHOLERA TOXIN - overactivates adenylate cyclase –> increases cAMP by permanently activating Gs –> increases Cl secretion in gut and water efflux –> voluminous “rice water” stool
How does Bordetella pertussis toxin (Pertussis toxin) inhibit phagocytic activity?
Overactivates adenylate cyclase –> increases cAMP by disabling Gi –> impairing phagocytosis to permit survival of microbe
What is the mechanism of the exotoxin of Clostridium tetani?
TETANOSPASMIN: protease cleaves SNARE proteins required for release of inhibitory NT’s GABA and glycine –> spasticity, rises sardonicus, and “lockjaw”
What is the mechanism of the exotoxin of Clostridium botulinum?
BOTULINUM TOXIN: protease cleaves SNARE proteins required for release of stimulatory ACh signals at neuromuscular junction –> flaccid paralysis or “floppy baby” (if ingested honey)
What is the mechanism of the exotoxin of Clostridium perfringens?
ALPHA TOXIN: phospholipase that degrades tissue and cell membranes –> myonecrosis and hemolysis
What is the mechanism of the exotoxin of Streptococcus pyogenes?
STREPTOLYSIN O: protein that degrades cell membrane –> lyses RBCs, contributes to beta-hemolysis
How do super antigens cause disease?
Bring MHC II and TCR in proximity to outside of Ag binding site –> causes overwhelming release of INF-gamma and IL-2 –> SHOCK
Name the two microorganisms that have super antigens.
S. aureus (TOXIC SHOCK SYNDROME TOXIN)
S. pyogenes (EXOTOXIN A)
What is transformation in basic bacteriology?
the ability to take up naked DNA (i.e. from cell lysis) from environment
Particular pathogens:
S. pneumoniae
H. influenzae type B
Neisseria
What is conjugation in basic bacteriology?
DNA transferred directly from one bacterium to another by conjugation
What is transposition in basic bacteriology?
a segment of DNA (e.g. transposon) that can “jump” (excision and reintegration) from one location to another
e.g. antibiotic resistance genes on R plasmid
What is transduction in basic bacteriology?
Generalized - a “packaging” event. LYTIC phage infects bacterium –> cleavage of bacterial DNA
Specialized - an “excision” event. LYSOGENIC phage infects bacterium –> viral DNA incorporates into bacterial chromosome
Genes for which microorganisms are encoded in a lysogenic phage?
ABCDE
ShigA-like Toxin Botulinum toxin Cholera toxin Diphtheria toxin Erythrogenic toxin