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Major Bacterial Genera – Flashcards

Ruth Blanco
7 July 2022

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

 

answer

Staphylococcus aureus

 

*iatrogenic, opportunistic pathogen

question
 

 

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

Staphylococcus saprophyticus & S. epidermidis

 

-Normal flora, rarely cause disease 

 

*saprophyticus = cystitis in sexually active women

 

*epidermidis = endocartitis w/ prosthetic heart valve

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

-alpha hemolysis

-


Streptococcus pyogenes

-beta hemolysis 

-Strep throat

*Superantigen toxin 

 

Group D Strep 

-gamma hemolysis (non-hemolytic)



Group D Strep

question
  • 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
answer

Enterococcus (faecalis)

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

-Frequent in nosocomial infections 

*Major Ab-resistance problem

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

Bacillus

 

B. cereus (food-poisoning, motile) 

 

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

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

Clostridium


*C. perfinges = Gas Gangrene  

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

 

Clostridium botulinum = flaccid paralysis 

 

Clostridium tetani = spastic paralysis 

question
  • 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
answer

Corynebacterium

*Can be club-shaped (chinese-letters)

 

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

Lactobacillus

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

question
  • 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 (4oC)
  • 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 
answer

Listeria monocytogenes

-common infection from unpasturized animal products

*doesn't matter if they are refridgerated 

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

Nocardia (asteroides, brasiliensis)

*opportunistic infection

-found in soil ; water

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

Actinomyces (israeli)

question
  • 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
answer

Neisseria

N. meningitidis (meningococcus)

*ferments glucose + maltose

N. gonorrhoaea (gonococcus)

*ferments glucose only

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

Acinetobacter

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

Moraxella (catarrhalis)

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

Serratia: nosocomial

Enterobacter: nosocomial

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

Klebsiella: pneumonia, UTI, GI infection

question
  • 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
answer

Proteus

 

question
  • 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
answer
Salmonella
question
  • 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
answer
Shigella 
question
  • 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
answer
Yersinia
question
  • Gram-negative curved rod
    • "gull-wing" shape
  • Oxidase-positive
  • Motile w/ polar flagellum
  • Microaerophilic 
  • Urease negative 
  • Bloody diarrhea 
  • Can survive warm temperatures (42oC)
answer
Campylobacter (jejuni)
question
  • 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 Gs activation
    • increases cAMP
  • "rice-water" diarrhea
answer
Vibrio cholerae
question
  • 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
answer
Helicobacter pylori
question
  • 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)
answer
Pseudomonas aeruginosa
question
  • 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
answer

Haemophilus (influenzae)


*most common cause of meningitis in children ; 6 years

question
  • 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 
answer

Bordetella pertussis 


(Whooping Cough)

question
  • 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
answer
Legionella (pneumophila)
question
  • Gram-negative small coccobacili
  • Oxidase-positive
  • Catalase-positive
  • Highly infectious 
  • Fastidious 
    • requires cysteine for growth
  • Bipolar staining
  • Zoonotic
  • Cellulitis/osteomyelitis following cat/dog bites 
answer
Pasteurella multocida
question
  • 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 
answer
Treponema pallidum
question
  • Gram-negative, small pleomorphic rod
  • Oxidase (+) 
  • Fastidious
  • Presents with undulating fever
  • Zoonotic
    • poorly pasturized goat cheese, animal byproducts (urine, placenta...farms)
answer
Brucella
question
  • Gram-negative, flexible, helical-shaped bacteria
  • Not reliably detected by Gram-stain
  • Endoflagellum
  • Contains Lipid A in LPS
  • Athropod-transmitted 
answer

Borrelia



*Associated with Lyme Disease (skin biopsy)

question
  • 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 
answer
Chlamydia & Chlamydophila
question
  • Gram-negative, but stain not useful
  • Cannot culture on semi-solid media
  • Obligate intracellular bacteria 
  • Transmitted by arthropods 
  • Replicate freely in cytoplasm 
answer
Rickettsia
question
  • Gram-negative, but stain not useful
  • Cannot culture on semi-solid media
  • Obligate intracellular bacteria 
  • Transmitted by arthropods 
  • Infect Leukocytes 
answer

Ehrlichia (macrophages/monophages)

 

Anaplasma (neutrophils)

question
  • 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 
answer
Coxiella
question
  • Lipid bilayer membrane contains sterols 
  • Lack a cell wall 
  • Pleomorphic 
  • Sensitive to environmental conditions 
  • Completely resistant to ?-lactam antibiotics
  • Fastidious 
  • Fried-egg appearance on Eaton's Agar 
  • Atypical pneumonia 
answer
Mycoplasma pneumoniae
question
  • 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
answer
Mycobacteria spp. (tuberculosis)
question
  • Gram-negative coccobacilli
  • Strict Anaerobe 
  • Bile Resistant & Hydrolyzes Esculin 
  • Normal Flora in colon 
  • Polysaccharide Capsule 
answer
Bacteroides fragilis
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