Flashcards in Random Micro Things that are annoying Deck (68):
Media used for H. influenzae culture
-Requires Factors V (NAD) and X (Hematin)
Media used for N. gonorrhoeae and N. meningitidis culture
Thayer-Martin agar (VCN)
-Vancomycin: inhibits gram pos organisms
-Colistin: inhibits gram neg except Neisseria
-Nystatin: inhibits fungi
Media used for B. pertussis culture
Bordet-Gengou agar (Bordet for Bordetella)
Regan-Lowe medium (contains charcoal, blood, Abx)
Media used for C. diptheriae culture
Media used for M. tuberculosis culture
Media used for M. pneumoniae culture
Eaton agar (requires cholesterol)
Media used for Lactose-fermenting enterics culture)
MacConkey agar (colonies turn pink)
Media used for E. coli culture
Eosin-methylene blue (EMB) agar
Media used for Legionella culture
Charcoal yeast extract agar buffered with cysteine and iron
Media used for Fungi culture
Sabouraud agar (Sab's a fun guy)
No cell wall
Which bugs don't gram stain well and why?
Treponema - too thin to be seen
Mycobacteria - high lipid content; mycelia acids in cell wall detected by carbolfuchsin in acid fast stan
Mycoplasma - no cell wall
Legionella - primarily intracellular
Rickettsia - intracellular parasite
Chalmydia - intracellular parasite; lacks classic peptidoglycan because of low muramic acid
Legionella, Fungi (pneumocystis), Helicobacter pylori
Ziehl-Neelsen (carbol fuchsin) stain
Acid-fast bacteria (Nocardia, Mycobacteria)
Protozoa (Cryptosporidium oocysts)
Alternative to Ziehl-Neelsen stain
PAS (periodic acid Schiff stain)
Stains glycogen, mucopolysaccharides, used to diagnose Whipple disease (Tropheryma whipplei)
Giemsa stain (Certain Bugs Really Try my Patience)
Which bacteria has the following?
a. Antiphagocytic capsule
b. Hypervariable pili
c. IgG binding outer membrane protein
d. Intracellular polyphosphate granules
a. Strep pneumo, H. influenzae, Neisseria
b. Neisseria meningitidis AND gonorrhea
c. Staph aureus (Protein A)
d. Corynebacterium diptheriae (evident with methylene blue stain)
Obligate Aerobes (Naggy Pests Must Breathe)
MycoBacterium tb (predilection for apices of lung which have highest pO2)
Obligate Anaerobes (Frankly Can't Breathe Air)
Properties of Anaerobes
Lack catalase and/or superoxide disputes so they are susceptible to oxidative damage
-Generally foul smelling (short chain fatty acids) and difficult to culture
-Produce gas in tissue (CO2 and H2)
Which antibiotic is ineffective against anaerobes? Why?
AminOglycOsides --> they require O2 to enter into bacterial cell
Obligate intracellular bugs (stay inside, it's Really CHilly COld)
-ALL rely on host ATP
Facultative intracellular bugs
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
Encapsulated bacteria (SHiNE SKiS) + P
Group B strep
How are encapsulated bacteria cleared?
Opsonized and cleared by spleen
Which bacteria have conjugate vaccines?
PCV (pneumococcal conjugate)
H influenzae type B
Urease positive (CHubby PUNKSS)
Catalase positive organisms (Cats Need PLACESS)
Abscesses commonly caused by?
Catalase + organisms
Bacteria that produce yellow sulfur granules
Bacteria with yellow pigment
Bacteria with blue green pigment
Bacteria with red pigment
Which organisms have IgA protease and what does it do?
Strep pneumo, H influenzae and Neisseria --> cleaves IgA so that they can colonize respiratory mucosa
Which bacteria have type III secretion system?
Toxin produced by bacteria and released
Exotoxin (gram + and -)
Location of exotoxin genes
Plasmid or bacteriophage
Are exotoxins and endotoxins heat stable?
Exotoxin - destroyed rapidly at 60 degrees celsius (except staph enterotoxin)
Endotoxin - stable at 100 degrees celsius for 1 hour
Corynebacterium diphtheria toxin
Exotoxin that inactivates elongation factor 2 --> pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck)
-Similar to Pseudomonas toxin
Pseudomonas aeruginosa toxin
Exotoxin A --> inactivates EF2 --> host cell death
-Similar to C. diphtheria toxin
Shiga toxin --> inactivates 60s ribosome by removing adenine from rRNA--> inhibits protein synthesis --> GI mucosal damage causes dysentery and ST also enhances cytokine release causing HUS
E. coli (EHEC) toxin
Shiga-like toxin (SLT) --> inactivates 60s ribosome by removing adenine from rRNA --> stops protein synthesis --> enhances cytokine release causing HUS (DOES NOT INVADE HOST CELLS LIKE SHIGELLA)
E. coli (ETEC) toxin
1. Heat labile (LT) --> overactivates adenylate cyclase to increase cAMP --> increase Cl secretion in gut and water efflux
2. Heat stable (ST) --> overactivates guanylate cyclase to increase cGMP --> decrease resorption of NaCl and H20 in gut
Bacillus anthracis toxin
Edema toxin --> mimics adenylate cyclase enzyme to increase cAMP and causes edematous borders of black eschar in cutaneous anthrax
Vibrio cholerae toxin
Cholera toxin --> overactivates adenylate cyclase to increase cAMP by permanently activating Gs --> increases Cl secretion in gut and water efflux --> rice water diarrhea
Bordetella pertussis toxin
Overactivates adenylate cyclase (increases cAMP) by disabling Gi --> impairing phagocytosis to permit survival of microbe --> whooping cough
Clostridium tetani toxin
Tetanospasmin --> protease that cleaves SNARE --> prevents release of inhibitory (GABA and glycine) neurotransmitters from Renshaw cells in spinal cord
Clostridium botulinum toxin
--> protease the cleaves SNARE to prevent release of stimulatory Ach signals at neuromuscular junction --> flaccid paralysis
Clostridium perfringens toxin
Alpha toxin --> phospholipase (lecithinase) that degrades tissue and cell membranes --> degradation of phospholipids --> myonecrosis and hemolysis
Streptococcus pyogenes toxin
Streptolysin O -->protein that degrades cell membrane --> lyses RBCs (host antibodies against toxin can be used to diagnose acute rheumatic fever)
Staph aureus toxin
Toxic shock syndrome toxin (TSST1) --> binds to MHCII and TCR outside of antigen binding site to cause overwhelming release of IL1, IL2, IFNy and TNFalpha --> shock
Strep pyogenes toxin
Exotoxin A --> binds to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL1, IL2, IFNy and TNFalpha --> shock
Actions of endotoxin (esp Lipid A)
Nitric oxide (hypotension)
DIC/Death (activates tissue factor)
TNF-alpha (fever and hypotension)
eXtremely heat stable
Neutrophil chemotaxis (C5a)
What is transformation?
Ability to take up NAKED DNA from environment (also known as competence)
Which bacteria can undergo transformation?
H. influenzae type B
How does adding deoxyribonuclease to environment affect transformation?
Deoxyribonucleases degrade DNA and there is no transformation
What are F+ bacteria?
F+ plasmid contains genes required for sex pilus and conjugation
What are F- bacteria?
Bacteria without the plasmid (conjugation)
What is F+ x F- conjugation?
The sex pilus on the F+ bacterium contacts the F- bacterium and a single strand of plasmid DNA is transferred across the conjugal bridge
NO TRANSFER OF CHROMOSOMAL DNA
What is Hfr x F- conjugation?
F+ plasmid can become incorporated into bacterial chromosome (high frequency recombination = Hfr) --> replication of incorporated plasmid DNA may include some flanking chromosomal DNA so there is transfer of plasmid AND chromosomal DNA (unlike F+ x F-)
What is transposition?
Segment of DNA (transposon) that can jump from one location to another and transfer genes from plasmid to chromosome and vice versa
What is generalized transduction?
A packaging event --> a lytic phage (virus) infects bacterium leading to cleavage of bacterial DNA --> parts of the bacterial chromosomal DNA may become packaged in viral capsid --> phage infects another bacterium and transfers these genes
What is specialized transduction?
Excision event where lysogenic phage infects bacterium and viral DNA incorporates into bacterial chromosome --> when phage DNA is excised the flanking bacterial genes may be excised with it --> the DNA is packaged into phage viral capsid and can infect another bacterium