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Bacterial Organisms – Flashcards

Gracie Stone

7 July 2022

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question

Gram positive cocci in clusters
Catalase positive
Facultative anaerobe
Ferments mannitol
DNase positive
Beta-hemolytic
Coagulase positive
One of the most important human pathogens
Causes Scalded Skin Syndrome and Toxic Shock Syndrome
Contains the exotoxins coagulase, fibrinolysin, lipase
Strains can be resistant to methicillin and vancomycin
Grows on PEA, Columbia CNA, and chocolate agar

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Staphylococcus aureus

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Gram positive cocci in clusters
Catalase positive
Coagulase negative
Does not ferment mannitol
DNase negative
Normal flora of skin and mucous membranes
Opportunistic pathogen; causes prosthetic valve endocarditis, urinary tract infections, wound infections
Gamma-hemolytic
Susceptible to novobiocin
Virulence factor is "slime"
Grows on blood, PEA, Columbia CNA, and chocolate agar

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Staphylococcus epidermidis

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Gram positive cocci in clusters
Found on skin and mucosal membranes of the genitoruinary tract
Common cause of urinary tract infections in young, sexually active females
Coagulase negative
DNase negative
Resistant to novobiocin
Grows on PEA, Columbia CNA, and chocolate agar

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Staphylococcus saprophyticus

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Gram positive cocci in pairs or chains
Catalase negative
Beta-hemolytic
Susceptible to bacitracin
Causes bacterial pharyngitis, rheumatic heart disease, acute rheumatic fever, pyoderma, necrotizing fasciitis
PYR positive
Contains streptolysins O and S, erythrogenic toxin, streptokinase, hyaluronidase
Bile esculin negative
Hippurate negative
A throat swab is used to collect a specimen
Catgorized as Lancefield A

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Streptococcus pyogenes (Group A)

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Gram positive cocci in pairs or chains
Catalase negative
Beta- or gamma-hemolytic
CAMP factor positive
Bacitracin resistant
Bile esculin negative
May be carried as normal flora in vaginal and gastrointestinal tract
Pregnant women should be screened for this bacteria
Major cause of neonatal meningitis and sepsis
Shows "arrowhead" hemolysis when grown on blood agar with beta-hemolytic S. aureus
PYR negative
Classified as Lancefield B

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Streptococcus agalactiae (Group B)

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Gram positive cocci in pairs that are lancet-shaped and arrange in chains
Requires 5-10% carbon dioxide on blood agar
Alpha-hemolytic
In 24 hr, mucoid colonies with a capsule
Susceptible to optochin
Causes community acquired pheumonia
Transmitted through respiratory droplets

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Streptococcus pneumoniae

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Gram positive cocci in pairs or chains
Alpha-hemolytic
Resistant to optochin
Bile resistant
Catalase negative
Normal flora of human oropharynx, gastrointestinal, and female genital tract
Causes subacute bacterial endocarditis

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Viridans streptococcus

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Gram positive cocci in pairs or chains
Catalase negative
Alpha- or gamma-hemolytic on blood agar
Bile esculin positive
PYR negative
Unable to grow in 6.5% NaCl broth
Susceptible to penicillin
Possess Lancefield Group D antigen

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Streptococcus bovis

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Gram positive cocci in pairs or chains
Catalase negative
Alpha- or gamma-hemolytic
Bile esculin positive
Grows in 6.5% NaCl broth
PYRase positive
Penicillin resistant
80-90% of human infections are caused by this species
Normal flora of gastrointestinal and genitoruinary tract, on the skin, and in oral cavity
May cause urinary tract infections, intra-abdominal abscesses, endocarditis

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Enterococcus faecalis

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Gram positive cocci in pairs or chains
Catalase negative
Alpha- or gamma-hemolytic
Bile esculin positive
Grow in 6.5% NaCl broth
PYRase positive
Penicillin resistant
Normal flora of the gastrointestinal and genitourinary tract, on the skin, and in oral cavity
May cause urinary tract infections, intra-abdominal abscesses, endocarditis
Causes 5-10% of human infections

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Enterococcus faecium

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Gram negative diplococci with flattened adjacent sides (kidney or coffee bean shape)
May resist decolorization
Oxidase positive
Catalase positive
Grows on chocolate agar, Modified Thayer-Martin, Martin-Lewis, New York City, and JEMBEC medium
Significant pathogen of urogenital tract
Dacron or rayon fibers are used to collect a specimen
Requires growth in 3-5% carbon dioxide
Utilizes glucose
Endocervical specimens are collected from females
Small, grayish white, convex, translucent, shiny colonies with either smooth or irregular margins on chocolate agar

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Neiserria gonorrhoeae

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Gram negative diplococci with "kidney or coffee bean" shape
Catalase positive
Oxidase positive
Utilizes glucose and maltose
Normal flora of upper respiratory tract, but can cause meningococcemia, septic shock with hemorrhage in the adrenal glands, and bacterial meningitis
Infection is spread in college dorms and miltary bases
Medium, smooth, round, moist, gray to white colonies on chocolate agar
Can grow on Thayer-Martin, modified Thayer-Martin, and Martin-Lewis agar

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Neiserria meningitidis

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Gram negative diplococci with "kidney or coffee bean" shape
Can resist decolorization and appear as gram positive cocci in pairs, tetrads, and small clusters
Oxidase positive
DNase positive
Cannot utilize carbohydrates
Normal commensal of respiratory tract
Causes upper respratory tract infections in healthy children and the elderly
Large, nonpigmented or gray, "hockey puck" colonies on chocolate agar
Clinicall significant when bacteria are accompanied with polymorphonuclear neutrophils

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Moraxella catarrhalis

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Gram negative bacilli
Catalase negative
Gamma-hemolytic
Oxidase negative
IMViC (indole, methyl red, VP, citrate): + + - -
Lysine positive
ONPG positive
TSI (triple sugar): A/A, H₂S negative
Yellow colonies on Hektoen Enteric/ XLD agar
Pink colonies on MacConkey agar
Resistant to penicillins, erythromycin, clindamycin, vancomycin, and ampicillin
Causes urinary tract infections, meningitis, Traveler's Diarrhea, dysentery

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Escherichia coli

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Gram negative coccobacilli
Catalase positive
ONPG negative
Reduces nitrate to nitrite
TSI: K/A, H₂S positive
IMViC: - + - +
Lysine positive
Positive motility
PYR negative
Contains O, H, and Vi antigens
Urease negative
Gamma-hemolytic
Red colonies with black centers on XLD agar
Clear colonies on MacConkey agar
Causes gastroenteritis and enterocolitis and typhoid fever

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Salmonella typhimurium

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Gram negative coccobacilli
Catalase positive
Oxidase negative
TSI: K/A, H₂S negative
IMViC: V + - -
ONPG negative
Negative motility
Urea negative
Gamma-hemolytic
Clear colonies on MacConkey agar
Green colonies on Hektoen enteric agar
Causes bacillary dysentery
Contains antigen B

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Shigella flexneri

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Gram negative coccobacilli
Catalase positive
Oxidase negative
ODC positive
ONPG positive
IMViC: V + - -
TSI: K/A, H₂S negative
Negative motility
Ornithine decarboxylase positive
Gamma-hemolytic
Urea negative
Smooth, round, bud-like colonies
Contains antigen D
Causes bacillary dysentery

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Shigella sonnei

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Gram negative coccobacilli
Oxidase negative
IMViC: + + - -
TSI: K/A, H₂S positive
Urea negative
Positive motility
ONPG negative
Most positive for lysin
Ferments glucose with gas production
Phenylalanine deaminase negative
Gamma-hemolytic

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Edwardsiella

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Gram negative coccobacilli
Oxidase negative
IMViC: - + - -
Nonmotile at 37 degrees Celsius
Urea negative
Ferments glucose
Reduces nitrate to nitrite
Gamma-hemolytic
Facultative anerobe
Primarily a disease of rodents
Agent of black plague

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Yersinia pestis

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Gram negative coccobacilli
Oxidase negative
IMViC: V + - -
Urea positive
Nonmotile at 37 degrees Celsius
"Bull's eye" colonies on CIN agar after 48 hrs.
Gamma-hemolytic
Can survive cold temperatures
Can mimic appendicitus and cause acute enteritis
Found in contaminated pork

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Yersinia enterocolitica

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Gram negative coccobacilli
Oxidase negative
Reduces nitrate to nitrite
IMViC: - + - -
Urea positive
Nonmotile at 37 degrees Celsius
Gamma-hemolytic

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Yersinia pseudotuberculosis

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Gram negative coccobacilli
Catalase negative
TSI: A/A, H₂S negative
IMViC: - - + +
Negative motility
Lysine positive
ONPG positive
PAD negative
Arginine negative
Gamma-hemolytic
Pink colonies on MacConkey agar
Yellow colonies on Hektoen enteric/ XLD agar
Causes pneumonia and urinary tract infections

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Klebsiella pneumoniae

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Gram negative coccobacilli
Catalase positive
Oxidase negative
IMViC: - - + +
TSI: A/A, H₂S negative
Lysine positive
Arginine negative
Urea negative
Reduces nitrate to nitrite
Gamma-hemolytic
Slightly mucoid, grey-white colonies
Pink colonies on MacConkey agar
Yellow colonies on Hektoen enteric/ XLD agar
Causes meningitis and urinary and respiratory infections

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Enterobacter aerogenes

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Gram negative coccobacilli
Catalase positive
Oxidase negative
IMViC: - - + +
TSI: A/A, H₂S negative
Reduces nitrate to nitrite
Urea positive
Positive motility
Pink colonies on MacConkey agar
Yellow colonies on Hektoen enteric/ XLD agar
Causes urinary tract infections, endocarditis, septic arthritis, respiratory infections

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Enterobacter cloacae

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Gram negative coccobacilli
Oxidase negative
Catalase negative
IMViC: - - + +
TSI: A/A, H₂S negative
Positive motility
Reduces nitrate to nitrite
ONPG positive
Lysine positive
Ornithine positive
Urease negative
Lipase negative
Gamma-hemolytic
Pink colonies on MacConkey agar
Colonies show a red pigment

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Serratia marcescens

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Gram negative coccobacilli
Oxidase negative
Catalase positive
IMViC: - + V V
TSI: K/A, H₂S positive
ONPG negative
Reduces nitrate to nitrite
Produces acid from glucose
Arginine negative
Lysine negative
Swarming motility
Ornithine positive
Gamma-hemolytic
Most frequent isolate from clinical specimens
Common cause of urinary tract infections and wound infections

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Proteus mirabilus

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Gram negative coccobacilli
Oxidase negative
Catalase positive
IMViC: + + - -
TSI: A/A, H₂S positive
Ornithine negative
Urea negative
Lysine negative
Arginine negative
ONPG negative
Gamma-hemolytic
Swarming motility

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Proteus vulgaris

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Gram negative coccobacilli
Oxidase negative
TSI: K/A, H₂S negative
Negative motility
PAD positive
Urea positive
Reduces nitrate to nitrite
Gamma-hemolytic
Clear or pale pink colonies on MacConkey agar
Yellow or colorless colonies on Hektoen enteric/ XLD agar

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Providencia

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Gram negative coccobacilli
Oxidase negative
IMViC: + + - -
TSI: K/A, H₂S negative
Urea positive
Negative motility
PAD positive
Ornithine positive
Gamma-hemolytic
Clear or pale pink colonies on MacConkey agar
Colorless or red colonies on Hektoen enteric/ XLD agar

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Morganella

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Gram negative coccobacilli surrounded by flagella
Catalase positive
Oxidase negative
IMViC: - + - +
TSI: K/A and A/A, H₂S positive
ONPG positive
Lysine negative
Ferments glucose, lactose, maltose, and sucrose
Low convex, gray, medium sized, translucent to opaque colonies with glossy surfaces
Normal flora of gastrointestinal tract
Causes urinary and respiratory tract infections, gastroenteritis

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Citrobacter freundii

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Gram negative coccobacilli
Oxidase negative
Positive motility
Indole negative
Urease negative
VP positive
Lysine positive
ONPG positive
Ferments glucose with gas production
Gamma-hemolytic
Reduces nitrate to nitrite

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Hafnia

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Gram negative coccobacilli
Oxidase positive
Ferments glucose and inositol but not lactose or sucrose
Gamma-hemolytic
Reduces nitrate to nitrite
Motile by a polar flagella
Shiny, opaque colonies

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Plesiomonas

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Long, thin gram negative bacilli
Oxidase positive
Utilizes glucose, fructose, and xylose but not lactose or sucrose
Single polar flagellum
May be encapsulated
Aerobic but can grow without oxygen if nitrate is available as a respiratory electron acceptor
Aluminum foil or metallic sheen
Sweet, fruity odor
Characteristic of cystic fibrosis patients
Fluoresces under UV light
Rough, spreading colonies with ground glass appearance and serrated or jagged edges

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Pseudomonas aeruginosa

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Gram negative bacilli
Catalase positive
Oxidase positive
Nonproteolytic
Gelatin negative
Positive motility
Arginine positive
Yellow fluorescent colonies
Causes urinary tract and wound infections
Cannot grow above 35 degrees Celsius

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Pseudomonas putida

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Gram negative bacilli
Catalase positive
Oxidase positive
DNase negative
Utilizes glucose and mannitol
Medium to large, mucoid, smooth, white colonies on blood agar
Mostly causes plant infections and food spoilage

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Pseudomonas fluorescens

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Gram negative bacilli
Weak positive catalase test
Positive motility
DNase negative
Lysine positive
Oxidizes glucose, maltose, lactose, and mannitol
Lactose negative
Resistant to aminoglycosides
Smooth and slightly raised yellow or green colonies on blood agar with a "dirt-like" odor

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Burkholderia cepacia

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Gram negative bacilli
Oxidase positive
Positive motility
Oxidizes lactose
Arginine positive
Resistant to colistin and polymyxin B
Nonlactose fermentor on MacConkey agar, but can appear pink after 4-7 days
Musty or earthy odor
Smooth and mucoid or dry and wrinkled colonies on blood agar
Etiologic agent of melioidosis

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Burkholderia pseudomallei

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Pleomorphic, aerobic gram negative bacilli
Appears as coccobacillus in singles, pairs, and short chains
Can resemble as gram positive cocci when grown in liquid medium or direct Gram stains
Oxidase negative
Nonmotile
Gamma-hemolytic
Nonlactose fermenter
Gelatin and lysine negative
Called "Iraqibacter"
Nosocomial pathogen; causes severe pneumonia and bloodstream and urinary tract infections

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Acinetobacter baumannii

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Gram negative bacilli
Oxidase negative
Catalase positive
Weakly oxidizes maltose and glucose
DNase positive
ONPG positive
Arginine negative
Ornithine negative
Decarboxylates lysine
Causes pneumonia and cystic fibrosis, urinary tract infections through Foley catheters, bloodstream infections through intravenous lines

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Stenotrophomonas maltophilia

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Gram negative bacilli
Oxidase negative
Positive motility
Nitrate positive but nitrite negative
Asaccharolytic
"Green apple" odor
Thin, spreading colony with irregular edges on blood agar; can produce green discoloration
Opportunistic pathogen

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Alcaligenes faecalis

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Gram negative bacilli
Catalase negative
Oxidase positive
Oxidizes glucose and xylose
Reduces nitrate to nitrite
Causes cirrhosis, bacteriemia, meningitis, pneumonia, peritonitis
White, smooth, round colonies on blood agar

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Achromobacter

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Gram negative bacilli
Catalase positive
Oxidase positive
PDA positive
Utilizes glucose, lactose, and sucrose
Positive motility
Causes urinary tract infections and urosepsis

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Oligella

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Gram negative bacilli
Polar, sheatheed flagella when grown in broth, but have peritrichous unsheathed flagella when grown on solid media
Oxidase positive
Facultative anaerobe
Urease negative
Citrate positive
Indole positive
Causative agent of cholera or epidemia cholera
Must grow on thiosulfate citrate bile salts (TCBS) sucrose agar and other enrichment media
Incubation period is 8-48 hrs.

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Vibrio cholerae

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Gram negative, straight, comma-shaped, or curved bacilli with a single polar flagellum
Catalase positive
Sucrose negative
Gamma-hemolytic
LDC positive
ADH negative
Requires growing in increased CO₂ and salt environment
Found in shrimp, oysters, crabs

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Vibrio parahaemolyticus

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Gram negative straight, comma-shaped, or curved bacilli with a single polar flagellum
Catalase positive
LDC positive
ADH negative
Sucrose negative
Grow in increased CO₂ and salt environment
Found in shrimp, oysters, and crabs
Causes gastroenteritis, wound infections, septicemia

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Vibrio vulnificus

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Gram negative straight, comma-shaped, or curved bacilli with a single polar flagellum
Catalase positive
Sucrose negative
VP negative
Found in shrimp, oysters, and crabs
Grow in increased CO₂ and salt environment
Causes gastroenteritis, wound infections, septicemia

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Vibrio mimicus

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Gram negative straight, comma-shaped, or curved bacilli with a single polar flagellum
Catalase positive
Sucrose positive
VP positive
LDC positive
ADH negative
Found in shrimp, oysters, and crabs
Grow in increased CO₂ and salt environment
Causes gastroenteritis, wound infections, and septicemia

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Vibrio anginolyticus

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Gram negative bacilli with spirals and seagull wings
Catalase positive
Oxidase positive
Hippurate negative
H₂S positive
CAMPY-BAP is used to isolate this species
Must grow in microaerophilic and capnophilic environment with gas mixture of approximately 85% N and 5-10% O₂ and 10% CO₂
Incubation is at 42 degrees Celsius
Causes Guillain-Barre

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Camplyobacter

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Small gram negative bacilli
Catalase positive
Oxidase positive
Xylose positive
ALA negative
Reduces nitrates
Requires both factors X and V
Gamma-hemolytic
Most important virulence factor is capsule
Most common cause of bacterial otitis media and acute sinusitis

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Haemophilus influenzae

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Small gram negative coccobacilli
Catalase positive
Oxidase positive
Xylose negative
ALA negative
Requires both factors X and V to grow
Gamma-hemolytic
Causes meningitis in children
Likes to grow around S. aureus
Needs moisture to grow

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Haemophilus influenzae aegyptius

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Tiny gram negative bacilli resembling "school of fish"
Catalase positive
Oxidase positive
ALA negative
Gamma-hemolytic
Cannot utilize glucose, sucrose, lactose, and fructose
Requires X factor to grow
Causes chancroid, a venereal disease

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Haemophilus ducreyi

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Gram negative bacilli
Catalase positive
Oxidase negative
Ferments glucose
Urease negative
Requires chocolate agar with IsoVitale X^TM or charcoal-yeast agar to grow
Agent of tularemia

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Francisella tularensis

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Gram negative coccobacilli
Catalase positive
Oxidase positive
Flat, wet colonies on sheep blood and chocolate agars
Transmitted through bites, scratches, and licking of skin breaks by dogs, cats, and other animals
Contains endotoxin, capsule, hemagglutins, and cytotoxins as virulence factors
Purulent material or tissue from bite wound are usually examined

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Pasteurella

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Gram negative bacilli
Nonmotile
Strict aerobe
Smooth, mucoid, convex colonies resembling "mercury drops" with a pearly luster on Bordet-Gengou medium with 20% blood with diffuse zone of hemolysis after 7 days
Requires 3-7 days incubation in moist container
Best cultured on charcoal-containing medium and Bordet-Gengou medium with 20% blood
Causes whooping cough

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Bordetella pertussis

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Gram negative bacilli
Catalase positive
Oxidase positive
Urease positive
Smooth, raised, and translucent colonies
Facultative intracellular pathogens that can reside within phagocytic cells
Spread through ingestion of unpasteurized milk
Causes undulant fever

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Brucella

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Gram negative bacilli
Catalase negative
Indole negative
Nitrate positive
Requires an increased CO₂ (5-10%) environment
Usual flora of oral cavity
Significant cause of endocarditis

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Aggregatibacter (Haemophilus) aphrophilus

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Gram negative bacilli
Catalase negative
Oxidase positive
Indole positive
Nitrate negative
Negative motility
Star-shaped centered colonies on blood agar
Require an increased CO₂ (5-10%) environment
Will not grow on MacConkey agar
Usual flora of oral cavity

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Aggregatibacter (Actinobacillus) actinomycetemcomitans

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Gram negative bacilli with bulbous (swollen) ends
Catalase negative
Oxidase positive
Indole positive
Urease negative
Nitrate negative
Glucose, sucrose, and mannitol positive
Requires increased CO₂ (5-10%) environment
Cannot grow on MacConkey agar
Causes endocarditis
Usual flora of oral cavity

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Cardiobacterium hominis

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Gram negative bacilli
Oxidase positive
Catalase negative
Indole negative
Nitrate positive
Glucose, mannitol, and sucrose negative
Requires an increased CO₂ (5-10%) environment
Significant cause of endocarditis
Usual flora of oral cavity
Produces a bleach-like odor

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Eikenella corrodens

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Gram negative plump bacilli in chains
Oxidase positive
Catalase negative
Indole negative
Nitrate negative
Glucose positive
Colonies show small but distinct zones of beta-hemolysis

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Kingella

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Gram negative filamentous bacilli
Catalase negative
Oxidase negative
Indole negative
Urease negative
Requires media enriched with whole blood, serum or ascitic fluid
Circular, convex, gray, smooth, glistening colonies with a fried egg appearance
Normal flora of oropharynx of rodents
Causes Rat Bite Fever and Haverhill Fever

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Streptobacillus moniliformis

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Gram negative bacilli
Catalase positive
Oxidase positive
Ferments glucose, trehalose, N. acetylglucosamine, and gluconate
Cannot ferment L-arabinose, D-galactose or D-maltose
Rare cause of human infection

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Chromobacterium violaceum

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Gram negative bacilli
Catalase positive
Oxidase positive
Sucrose negative
H₂S positive
Small, opaque, yellow-pigmented, shiny, nonhemolytic colonies
Causes bacteriemia following dog bites

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Capnocytophaga

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Large, sporeforming gram positive bacilli in chians
Gamma-hemolytic
Spores viable for up to 50 years
Produces acid from glucose, sucrose, and maltose
Susceptible to penicillin
Negative motility
Can grow on Columbia colistin-nalidixic acid (CNA) agar, bicarbonate agar, mannitol-egg yolk-polymyxin (MYP), polymyxin-egg yolk-mannitol bromothymol blue agar
Causes anthrax, Wollsorters' disease, adn progressive endophthalmitis

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Bacillus anthracis

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Large, sporeforming gram positive bacilli in chains
Beta-hemolytic
Positive motility
Resistant to penicillin
Citrate positive
VP positive
Gelatin hydrolysis positive
Associated with fried rice
Causes opportunistic infections of the eye, as well as meningitis, septicemia, and osteomyelitis
Causes diarrheal syndrome

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Bacillus cereus

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Gram positive bacilli, appearing in pallisades and give "Chinese letter" arrangement
Catalase positive
Does not produce spores
Non-acid fast
Ferments glucose, maltose, and sucrose
Produces a halo on cysteine-tellurite blood agar and modified Tinsdale (TIN) agar
Methlyene blue smear is used to detect granules
Produces metachromatic graules ("Babes' Ernst" bodies)
Causes diphtheria

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Corynebacterium diphtheriae

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Gram positive bacilli
Catalase positive
Oxidase positive
Lipophilic positive
Urease negative
Non-acid fast
Produces no spores
Pinpoint, white colonies on blood agar
Causes nosocomial infections and septicemia, skin infections,a nd other infections in immunocompromised hosts

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Corynbacterium jeikeium

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Gram positive non-spore forming coccobacilli
Catalase positive
Ferments glucose
VP positive
Esculin hydrolysis positive
"Umbrella" motility at 25 degrees Celsius
Produces a "block" type of hemolysis in CAMP test
Grows in 6.5% NaCL
Patients who are immunocompromised and women who are pregnant should avoid eating soft cheeses

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Listeria monocytogenes

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Long and filamentous, non-spore forming gram positive bacilli
Also may appear as coccobacillary in chains and palisades and pleomorphic gram positive bacilli
Catalase, H₂S, motility, esculin, glucose, nitrate, and urease negative
Commensal or normal flora in the oral cavity, gastrointestinal tract, and female genital tract
Tiny, pinpoint, alpha-hemolytic to large, rough, gray colonies on blood agar
Causes bacteriemai, enodcarditis, and pneumonia

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Lactobacillus

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Gram positive, non-spore forming, pleomorphic bacilli that may form long filaments, may be arranged singly, in short chains, or in a V shape
Catalase negative
Produces H₂S on TSI agar
Can cause disease in animals (swine, turkey, sheep)
Humans acquire infection through occupational exposure

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Erysipelothrix rhusiopathiae

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Gram positive, non-spore forming, short, pleomorphic bacilli or coccobacilli
Catalase and oxidase negative
Hippurate hydrolysis positive
Beta-hemolytic on human blood agar, but gamma-hemolytic on sheep blood agar
Produces small, gray, opaque colonies with diffuse zone of beta-hemolysis
Associated with bacterial vaginosis
Results in foul-smelling discharge and vaginal pH greater than 4.5
Observation of clue cells in wet mounts is helpful
Sensitive to metronidazole and ampicillin

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Gardnerella vaginalis

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Gram positive bacilli with terminal spores, resembling a tennis racket, lollipop, or drumstick
Catalase negative
Slightly beta-hemolytic
Lipase positive
Lecithinase negative
Obligate anaerobe
Produces powerful neurotoxin that causes constant muscle contraction
Grows on egg yolk agar
Causes tetanus

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Clostridium tetani

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Gram positive bacilli with subterminal spores
Catalase negative
Lipase positive
Obligate anaerobe
Exotoxin is detected in serum, stool, and food
Grows on egg yolk agar
Infants should not eat honey when this bacteria is present
Causes infantile botulism after ingestion of spores

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Clostridium botulinum

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Large, straight-edged gram positive bacilli in chains
Usually unwilling to produce its central or subterminal spore
Exhibits double zone of beta-hemolysis
Lipase negative
Lecithinase positive
Indole negative
DNase positive
Positive motility
Black colonies with 2-4mm opaque white zone on egg yolk agar
Causes gas gangrene,m myonecrosis, pleuropulmonary infections, and post-abortion sepsis

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Clostridium perfringens

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Gram positive bacilli with subterminal spores
Catalase negative
Lecithinase negative
Ferments glucose and fructose
Poistive motility
Obligate anaerobe
Characteristic horse manure or barnyard odor
Most common causative agent of antibiotic associated diarrhea and pseudomembranous colitis
Specimen (fresh stool) should be planted on anaerobic blood agar and cycloserine cefoxitin fructose agar (CCFA)
Clinically significant when it produces toxins

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Clostridium difficile

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Long, thin gram positive bacilli that branch like a tree and grow in a mass
Can break into short club-shaped rods
May have abeaded or banded look
Reduces nitrates
Catalase and indole negative
Characteristic white molar tooth colony
Aerotolerant, but grows better under anaerobic conditions
Normal flora of upper respiratory, gastrointestinal, and female genital tracts
Causes purulent masses to form as weel as sinus tracts with discharge that can contain sulfur granule colonies

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Actinomyces israelii

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Clubbed, pleomorphic, pallisading gram positive bacilli (anaerobic diphtheroids)
Catalase, indole, and nitrate positive
Aerotoleratn, but grows best in anaerobic environment
Normal skin flora
Most frequent blood culture contaminant
Causes acne and prosthetic infections in heart, valves, and joints

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Propionibacterium acnes

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Gram negative coccobacilli or rods
Appear to ahve swellings or clear vacuoles in cells
Saccharolytic
Catalase positive
Bile resistant
Resistant to penicillin 2-unit disks
Obligate anaerobe
Grows well in 20% bile
Largest portion of normal gastrointestinal flora
Causes widespread tissue necrosis, appendicitis, and peritonitis

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Bacteriodes fragilis

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Long, thin fusiform to very pleomorphic gram negative bacilli
Catalase negative
Resistant to vaoncomycin but sensitive to kanamycin and colistin
Growth not stimulated by 20% bile
Bread crumb-like colonies
Normal flora of oral tract, upper respiratory tract, and female genital tract

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Fusobacterium

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Gram negative cocci in pairs, short chains, or clumps
Indole positive
High sensitivity to oxygen
Requires growing in an anaerobic chamber or glove box
Resistant to vancomycin but sensitive to kanamycin and colistin
Commensal flora in oral cavity and respiratory and gastrointestinal tract
Causes prosthetic joint infections

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Veillonella

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Gram negative bacilli
Catalase poistive
Indole positive
Asaccharolytic
Will not grow on bile esculin
Susceptible to kanamycin
Brick red fluorescence under ultraviolet light
Requires incubation of 48 hrs. to 2 weeks
Normal flora of the oropharynx, nose, and urogenital and gastrintestinal tract

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Porphyromonas

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Long, thin, branching gram positive bacilli
Catalase negative
Partially acid fast
Requires incubation at 35-37 degrees Celsius for 72 hrs. - 4 weeks in 10% CO₂
Waxy, bumpy, velvety, yellow-orange colonies
Usually causes chronic repiratory and central nervous system infections and necrosis, abscesses, and skin infections

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Norcardia

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Gram positive cocci in pairs and chains
Catalase negative
H₂S positive
Reduces nitrate
Indole negative
Causes perodontitis and abdominal abscess
Can only grow on anaerobic PEA, CNA, or blood agar
Small, gray to white colonies on anaerobic blood agar with a sweet putrid odor

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Peptostreptococcus anaerobius

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Gram negative bacilli
Catalase negative
Indole positive
Inhibited by 20% bile
Lipase positive
Ferments glucose
Young colonies are tan/buff in color, whereas older colonies develop a brown pigment
Can grow on laked blood agar
Predominant commensal organism in the oral cavity that can cause oral infections
Normal flora of urogenital tract that can cause infections of the head, neck, and lower respiratory tract

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Prevotella intermedia

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Gram negative bacilli
Catalase negative
Indole negative
Esculin negative
Lipase negative
Black colonies on laked blood agar
Incubated for 2-3 weeks
Causes periodontal diseases, mouth abscesses, and endocarditis
Normal flora of upper respiratory tract

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Prevotella melaninogenica

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Gram negative narrow bacilli, but Gram stain is poor
Gelatinase positive
Positive motility
Urease negative
Nitrate reduction negative
Cannot grow on blood agar, but can grow on buffered charcoal yeast extract (BCYE) agar
Requires L-cysteine and a soluble form of iron to grow
Cannot survive in dry environments
Circular, glistening, and convex colonies with an entire margin
Causes Pontiac fever and Legionnaire's disease

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