• Gram-positive cocci 
• Catalase positive
• Coagulase positive
• β-hemolytic & Haloduric (grows on Mannitol Salt Agar)
• Produces acid from mannitol
• agar changes from red to yellowish color

Staphylococcus aureus

*iatrogenic, opportunistic pathogen

• Gram positive cocci in cluster
• Catalase positive
• Coagulase Negative

Staphylococcus saprophyticus & S. epidermidis

-Normal flora, rarely cause disease 

*saprophyticus = cystitis in sexually active women

*epidermidis = endocartitis w/ prosthetic heart valve

• Gram-positive cocci in pairs or clusters
• Catalase-negative
• Microaerophilic 
• Hemolysis patterns 
• alpha, beta, gamma 
• Lancefield Ab to cell wall carbohydrates

Streptococus pneumoniae

-alpha hemolysis

-

Streptococcus pyogenes

-beta hemolysis 

-Strep throat

*Superantigen toxin 

Group D Strep 

-gamma hemolysis (non-hemolytic)

Group D Strep

• Gram positive cocci in chains
• Catalase negative
• Microaerophilic
• Lancefield Group D Ag-positive
• Surface-Active Superantigen Exotoxin
• Resistant to Bile Salts 
• Grows on Bile Esculin agar
• Some species precipitate black on this agar

Enterococcus (faecalis)

-part of normal GI flora, seldom causes disease in healthy

-Frequent in nosocomial infections 

*Major Ab-resistance problem

• Gram positive Rod
• Spore-forming
• sigma sporulation genes 
• Aerobic 

Bacillus

B. cereus (food-poisoning, motile) 

B. anthracis (anthrax, inhalation, non-motile)

• Gram-positive rod 
• Spore-forming
• Obligate Anerobe 
• Found in human GI

Clostridium

*C. perfinges = Gas Gangrene  

-alpha-toxin (lecithinase) utilizes Phospholipase to target RBCs, resulting in disease

Clostridium botulinum = flaccid paralysis 

Clostridium tetani = spastic paralysis 

• Gram-positive rod
• Non spore-forming
• Appear gray/black w/ halo on Tellurite Agar
• Organisms stack on each other, forming a palacade
• Aerobic (faculative anaerobe)
• AB-protein utlizes ADP-ribosylation to inhibit elF2

Corynebacterium

*Can be club-shaped (chinese-letters)

• Gram-positive rod
• Non spore-forming
• Part of normal flora
• Anerobic (with wide range of oxygen requirements)

Lactobacillus

-utilizes glycogen in vagina in exchange for lactic acid production (creates acidic environment, protective)

• Gram-positive rod
• Non spore-forming
• Aerobic (faculative anaerobe)
• Catalase (+)
• Beta-hemolytic 
• Pore-forming exotoxin = escape from phagosome
• Tolerates salt/pH
• Will grow at lower temperature (4^oC)
• Faculative intracellular organism 
• "tumbling" motility in cultures 
• Acquired through animal products 
• Infects both Phagocytic & Non-phagocytic Cells 
• Utlizes ActA surface protein which facilitates translocation into neighboring cells 

Listeria monocytogenes

-common infection from unpasturized animal products

*doesn't matter if they are refridgerated 

• Gram-positive rod
• Non spore-forming
• Filamentous, branching (resembles fungi)
• Weakly acid fast
• Aerobic 

Nocardia (asteroides, brasiliensis)

*opportunistic infection

-found in soil & water

• Gram-positive rod
• Non spore-forming
• Filamentous, branching (looks like fungi)
• Anaerobic 
• Normal Respiratory Flora

Actinomyces (israeli)

• Gram-negative diplococci
• Oxidase (+)
• Catalase (+)
• Ferments Glucose & Maltose (not lactose)
• Visualized by Quellung Reaction
• Non-motile (twich motility via Type IV pili)
• Has LOS, not LPS
• Releases endotoxin from intact, living cells 
• Found associated with PMN cells
• Grows on Thayer-Martin Chocolate Agar
• in atomsphere of 5% CO₂

Neisseria

N. meningitidis (meningococcus)

*ferments glucose + maltose

N. gonorrhoaea (gonococcus)

*ferments glucose only

• Gram-negative cocci
• coccobacillary appearance
• Frequently resistant to antibiotics
• Nosocomial pathogen

Acinetobacter

• Gram-negative cocci
• coccobacillary appearance 
• Can cause otitis media, bactermia, meningitis
• Normal respiratory flora (not inanimate objects)

Moraxella (catarrhalis)

• Gram-negative rod
• Ferments Glucose
• Oxidase-negative
• Normal habitiat is human GI tract
• Grows on MacConkey Agar
• Lactose-fermenting (pink)

Serratia: nosocomial

Enterobacter: nosocomial

Escerichia: GI infection (epidemic), UTI, etc.

Klebsiella: pneumonia, UTI, GI infection

• Gram-negative rod
• Ferments Glucose
• Oxidase-negative
• Normal habitiat is human GI tract
• Produce hydrogen sulfide (black precipitate)
• Swarming motility
• Urease-positive
• O-Antigen
• Appears clear on MacConkey Agar
• cannot ferment lactose

Proteus

• Gram-negative rod
• Ferments Glucose
• Oxidase-negative
• Normal habitiat is human GI tract
• Produce hydrogen sulfide (black precipitate)
• Motile
• H-Antigen (flagella)
• Appears green/transparent on Hektoen Enteric Agar
• Visualized via Quellung Reaction
• Appears clear on MacConkey Agar
• cannot ferment lactose

• Gram-negative rod
• Ferments Glucose
• Oxidase-negative
• Normal habitiat is human GI tract
• Non-hydrogen sulfide producing
• Non-motile
• Low infectious Dose 
• O-Antigen present 
• Appears green/transparent on Hektoen Enteric Agar
• Appears clear on MacConkey Agar
• cannot ferment lactose

• Gram-negative short/pleomorphic rod
• Bi-polar staining (safety pin)
• Ferments Glucose
• Oxidase-negative
• Non-hydrogen sulfide producing
• Iron acquisition system via HPI island
• Appears green/transparent on Hektoen Enteric Agar
• Appears clear on MacConkey Agar
• cannot ferment lactose

• Gram-negative curved rod
• "gull-wing" shape
• Oxidase-positive
• Motile w/ polar flagellum
• Microaerophilic 
• Urease negative 
• Bloody diarrhea 
• Can survive warm temperatures (42^oC)

• Gram-negative curved rod
• comma/boomerang-shaped
• Oxidase-positive
• Lactose non-fermenter
• Glucose fermenter
• Urease negative 
• Can survive alkaline environment 
• A:5B-protein utlizes ADP ribosylation for G_s activation
• increases cAMP
• "rice-water" diarrhea

• Gram-negative spiral-shaped rod
• Motile w/ polar flagellum
• Oxidase-positive
• Catalase Positive
• Microaerophilic 
• Urease positive 
• Can survive acidic environment 
• Type IV secretion on CagA island: ULCERS

• Gram-negative rod
• Oxidase-positive
• Do not ferment glucose or lactose
• Motile w/ flagella
• Fruity, grape-like odor
• Blue-green pigment
• Obligate aerobe 
• Frequently a nosocomial pathogen (burn victims)

• Gram-negative rod
• Requires hemin (X factor) & NAD (V factor) on Chocolate Agar
• does NOT grow well on Blood Agar
• Positive Quellung Test
• Only human carriers
• Fastidious

Haemophilus (influenzae)

*most common cause of meningitis in children < 6 years

• Gram-negative rod
• Oxidase-positive
• Filamentous hemagglutinin (FHA)
• Requires Bordet-Gengou medium
• blood & charcoal to neutralize inhibitors
• Fastidious 
• Obligate Aerobe 
• Type III Secretion System 
• Infects Respiratory Tract 

Bordetella pertussis 

(Whooping Cough)

• Gram-negative rod, stains poorly 
• Obligate Aerobe
• Facultative Intracellular
• Fastidious
• Requires Buffered Charcoal-Yeast Agar  (BCYE)
• w/ iron & cysteine
• Motile w/ polar flagellum
• Invades & survives within Alveolar Macrophages 
• Prevents fusion of pahgocytic vacuole & endolysosome --> changes membrane
• Cause of atypical pneumonia  
• Contaminates Water Sources

• Gram-negative small coccobacili
• Oxidase-positive
• Catalase-positive
• Highly infectious 
• Fastidious 
• requires cysteine for growth
• Bipolar staining
• Zoonotic
• Cellulitis/osteomyelitis following cat/dog bites 

• Gram-negative, flexible, helical-shaped bacteria
• Endoflagellum
• Microaerophilic 
• Contains Lipid A in LPS
• Sensitive to high temperatures 
• Not reliably detected by Gram-stain
• visualized by dark-field microscopy or fluorescent Ab-staining 

• Gram-negative, small pleomorphic rod
• Oxidase (+) 
• Fastidious
• Presents with undulating fever
• Zoonotic
• poorly pasturized goat cheese, animal byproducts (urine, placenta...farms)

• Gram-negative, flexible, helical-shaped bacteria
• Not reliably detected by Gram-stain
• Endoflagellum
• Contains Lipid A in LPS
• Athropod-transmitted 

Borrelia

*Associated with Lyme Disease (skin biopsy)

• Gram-negative, but stain not useful
• Cannot culture on semi-solid media
• Obligate intracellular bacteria 
• lack mechanism for ATP & NAD production
• Replicate within Inclusion body 

• Gram-negative, but stain not useful
• Cannot culture on semi-solid media
• Obligate intracellular bacteria 
• Transmitted by arthropods 
• Replicate freely in cytoplasm 

• Gram-negative, but stain not useful
• Cannot culture on semi-solid media
• Obligate intracellular bacteria 
• Transmitted by arthropods 
• Infect Leukocytes 

Ehrlichia (macrophages/monophages)

Anaplasma (neutrophils)

• Gram-negative, but stain not useful
• Cannot culture on semi-solid media
• Obligate intracellular bacteria 
• specialized for living inside fused phagolysosome
• Zoonoses (Farm animals)
• Transmitted via inhalation 
• Resistant to drying 

• Lipid bilayer membrane contains sterols 
• Lack a cell wall 
• Pleomorphic 
• Sensitive to environmental conditions 
• Completely resistant to β-lactam antibiotics
• Fastidious 
• Fried-egg appearance on Eaton's Agar 
• Atypical pneumonia 

• Small, Straight Rods 
• Stain poorly by gram-stain
• Acid-fast staining
• Resistant to phagocytosis, germicides, dryness
• Waxy cell envelope prevents uptake of dyes 
• mycolic acid

• Gram-negative coccobacilli
• Strict Anaerobe 
• Bile Resistant & Hydrolyzes Esculin 
• Normal Flora in colon 
• Polysaccharide Capsule