Clinical Microbiology

Chocolate agar with factors V (NAD⁺) and X (hematin)
H. Influenzae
Thayer-Martin (or VPN) media - Vanco inhibits gram(+) organisms, Polymyxins inhibits gram (-) organisms, and Nystatin inhibits fungal organisms.
Neisseria Gonorrhoeae
Bordet-Gengou (potato) agar
Bordetella Pertussis
Cystine-Tellurite Plage, Loffler's media
C. Diphtheriae
Lowenstein-Jensen agar
M. Tuberculosis
Eaton's Agar
Mycoplasma Pneumoniae
MacConkey's agar (fermentation produces acid, turning plate pink.
Lactose-fermenting enterics
Eosin-methylene blue agar, blue-black colonies with metallic sheen
E. Coli
Charcoal Yeast extract agar
Sabouraud's agar
Giemsa stain
Borrelia, Plasmodium, Trypanosomes, Chlamydia
PAS - stains glycogen, mucopolysaccharrides
Topheryma Whippleii
Acid-fast organisms (mycolic acids)
India Ink(negative stain)/Mucicarmine(pink)
Cryptococcus neoformans
Silver stain
Fungi (e.g. pneumocytis), Legionella
KOH preparation
Catalase test
Differentiates Staphylococcus from Streptococcus
Coagulase test
Differentiates S. Aureus from S. epidermidis/saprophyticus
Novobiocin sensitivity
Differentiates S. epidermidis (sensitive) from S. saprophyticus (resistant)
Gamma hemolytic
No hemolysis - Enterococcus (E. feacalis), Peptostreptococcus, S. Bovis
6.5% NaCl test
Differentiates E. Feacalis (positive) from S. Bovis (negative)
Optichin sensitivity
Differentiates S. Pneumoniae (sensitive) from Viridans Streptococci (resistant)
Alpha hemolytic
Partial hemolysis/green - S. Pneumoniae, Viridans Strep, and some Group D Strep
Growth on Bile-esculin agar (extremely salt resistant)
Group D streptococci
Beta Hemolytic
Complete hemolysis - Group A S. pyogenes and Group B S. agalactiea. Also S. Aureus and Listeria Monocytogenes.
Bacitracin sensitivity
Differentiates S. Pyogenes (sensitive) from S. Agalactiae (resistant)
CAMP test (produces CAMP factor)
Group B streptococcus (agalactiae)
Maltose Fermentation test
Differentiate Neisseria species - N. Meningitidis (fermenter), N. Gonorrhoeae (non-fermenter)
Lactose fermentation test
Differentiates gram (-) rods from each other.
Fast Lactose fermenters
Klebsiella, E. Coli, Enterobacter
Slow Lactose fermenters
Citrobacter, Serratia
Oxidase test
Differentiates Lactose Non-fermenters from each other.
Oxidase(+), Lactose non-fermenters
Oxidase(-), Lactose non-fermenters
Shigella, Salmonella, Proteus
Obligate aerobes
Pseudomonas aeruginosa
Mycobacterium tuberculosis
Obligate anaerobes; Aminoglycosides ineffective, susceptible to oxidative damage.
Obligate intracellular bugs; can't make own ATP
Facultative Intracellular bugs
Encapsulated bacteria (+ Quellung); antiphagocytic virulence factor --> require opsonization for clearance.
S. pneumoniae
H. Influenzae B
Neisseria meningitidis
Urease + bugs
Ureaplasma Urealyticum
H. Pylori
Yellow pigment production
S. Aureus
Blue-green pigment
Pseudomonas aeruginosa
Red pigment
Serratia marcescans
IgA protease production; used to colonize respiratory mucosa
S. pneumoniae
H. influenzae B
N. meningitidis
M protein; prevent phagocytosis
Group A streptococcus
Protein A; binds Fc region of Ig, preventing opsonization and phagocytosis
S. Aureus
cAMP inducers; activate host adenylate cyclase, or are themselves adenylate cyclase.
Vibrio cholerae - activates Gs
Pertussis toxin - disables Gi
E. Coli (ETEC) - heat labile toxin
Bacillus anthracis - bacterial adenylate cyclase
Bind directly to MHC II and TCRs simultaneously, activating large #'s of T cells to stimulate release of IFN-γ and IL-2 --> septic shock.
S. aureus toxins
TSST-1 = toxic shock syndrome

Enterotoxin A = food poisoning (preformed), in meat, mayo, and creamy pastry dishes; nausea and vomitting 3-6 hours after eating, little to no diarrhea.

Exfoliatin = staphylococcal scalded skin syndrome
S. pyogenes toxin
Erythrogenic toxin = toxic shock-like syndrome; assoc. with scarlett fever.
ADP ribosylating A-B toxins
Interfere with host cell function by entering host cell and altering protein fxn from within.
Corynebacterium diphtheriae toxin
Inactivates EF-2; causes pharyngitis and pseudomembrane in throat.
Pseudomonas aeruginosa toxin (ecthyma gangrenosum)
Inhibits EF-2; similar to diphtheria toxin.
Vibrio cholerae toxin
ADP ribosylation of G protein stimulates adenylyl cyclase; increases pumping of Cl⁻ into gut and decreases Na⁺ absorption. H₂O moves into gut lumen causing voluminous rice-water (secretory) diarrhea.
ETEC toxin
Heat-labile toxin stimulates Adenylate cyclase. Heat-stable toxin stimulates Guanylate cyclase. both cause watery/secretory diarrhea.
Bordatella pertussis toxin
Gram (-) aerobic bacillus, causes whooping cough (coughing, choking spells, and gasping for air);

Toxin inactivates inhibitory subunit of the G protein complex, activating adenylate cyclase, increasing cAMP in the cells of the respiratory system >> EDEMA. Toxin also causes LYMPHOCYTOSIS by blocking chemokine receptors, blocks the function of immune effector cells and increases HISTAMINE SENSITIVITY. Toxin also alters hormonal pathways regulated by cAMP, increasing insulin secretion, causing HYPOGLYCEMIA.

Tx: erythromycin
Bacillus Cereus Toxin
Heat-stable toxin causing vomiting. From rice in the buffet line. Onset in less than 6 hours.
Clostridium perfringens toxin
α toxin causing gas gangrene; get double zone of hemolysis on blood agar.
C. tetani toxin
Blocks release of inhibitory GABA and glycine; causes spastic paralysis.
C. botulinum toxin
Blocks the release of ACh; causes anticholinergic symptoms, CNS flaccid paralysis, especially cranial nerves; spores found in canned food, honey (floppy baby).

Differentiate from all other anticholinergic drugs (e.g. atropine)by the presence of muscle weakness or paralysis.
Bacillus anthracis toxin
Edema factor is an adenylate cyclase, increases cAMP.
Shigella/EHEC toxin
Shiga toxin/verotoxin; cleaves host rRNA (inactivate 60S); enhances cytokine release, causes Hemolytic-uremic syndrome.
S. pyogenes toxin
Streptolysin O is a hemolysin; antigen for ASO antibody is used for rheumatic fever diagnosis.
Lipopolysaccharide found in outer membrane of all gram (-) bacteria (and listeria monocytogenes); Lipid A is toxic component.
Activates macrophages, alternative complement pathway, and Hageman factor to produce septic shock and DIC. Secretion of IL-1, IL-6, and TNFα
Bacterial toxins encoded on lysogenic phage
ShigA-like toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin (S. pyogenes)
O-antigen salmonella
Ability to take up DNA from environment; S. pneumoniae, H. influenzae, Neisseria.
Transfer of plasmid encoded virulence factors from one bacteria to another via pilus formation.
Transfer of bacteria DNA through incorporation of DNA into bacteriophage.

Site-specific Transduction: specific sequence, error of temperate virus life-cycle.
Generalized Transduction: random bacterial DNA, error of lytic virus life-cycle.
segments of DNA that can jump from one section of DNA to another, or from chromosome into phage DNA and viceversa.