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PHOTO GALLERY OF BACTERIA


TABLE OF MEDICALLY IMPORTANT BACTERIA
GRAM-POSITIVE BACTERIA
Gram-positive cocci

Staphylococcus

Gram stain: Gram-positive
Microscopic appearance: cocci in grape-like clusters
Oxygen relationship: facultatively anaerobic bacteria
Motility: nonmotile
Catalase test: catalase-positive
Oxidase test: negative*
Spores: non-spore forming
* Some species (non-human isolates) are positive
streptococcus image

Streptococcus

Gram stain: Gram-positive
Microscopic appearance: cocci in chains (liquid media)
or pairs
Oxygen relationship: facultatively anaerobic bacteria
Motility: nonmotile
Catalase test: catalase-negative
Oxidase test: negative
Spores: non-spore forming
enterococcus image

Enterococcus

Gram stain: Gram-positive
Microscopic appearance: cocci or ovoid cocci in pairs, clusters or short chains (liquid media)
Oxygen relationship: facultatively anaerobic bacteria
Motility: nonmotile or motile
Catalase test: catalase-negative
Oxidase test: negative
Spores: non-spore forming
Listeria image

Listeria

Gram stain: Gram-positive
Microscopic appearance: short rods (sometimes coccoid forms), single or in chains
Oxygen relationship: facultatively anaerobic bacteria
Motility: motile (at 20-25°C)*; peritrichous flagella
Catalase test: catalase-positive
Oxidase test: negative
Spores: non-spore forming
* optimal growth temperature at 30-37°C
Corynebacterium image

Corynebacterium

Gram stain: Gram-positive
Microscopic appearance: rods, often broader at one end
("club" shape), grouped together
in a characteristic way ("V", "palisades", "Chinese letters")
Oxygen relationship: facultatively anaerobic bacteria
Motility: nonmotile
Catalase test: catalase-positive
Oxidase test: negative
Spores: non-spore forming*
*metachromatic granules are often present.
Bacillus image

Bacillus

 
Gram stain: Gram-positive
Microscopic appearance: rods in chains
Oxygen relationship: aerobic or facultatively anaerobic bacteria
Motility: motile (peritrichous flagella) or nonmotile (e.g., B.anthracis)
Catalase test: catalase-positive
Oxidase test: negative
Spores: spore forming (endospores)
Lactobacillus image

Lactobacillus

Gram stain: Gram-positive
Microscopic appearance: rods in chains or palisades
Oxygen relationship: facultatively anaerobic or anaerobic bacteria
Motility: nonmotile (most of them)
Catalase test: negative
Oxidase test: negative
Spores: non-spore forming
Streptomyces image

Streptomyces

Gram stain: Gram-positive
Microscopic appearance: rods; form substrate and aerial mycelium
Oxygen relationship: aerobic bacteria
Motility: nonmotile
Catalase test: positive
Oxidase test: negative
Spores: spore forming (aerial mycelium)
Clostridium image

Clostridium

Gram stain: Gram-positive (young cultures), often Gram-variable
Microscopic appearance: rods (in pairs or chains)
Oxygen relationship: anaerobic bacteria
Motility: usually motile (peritrichous flagella)
Catalase test: negative
Oxidase test: negative
Spores: spore forming (endospores)
GRAM-NEGATIVE BACTERIA
neisseria image

Neisseria

Gram stain: Gram-negative
Microscopic appearance: diplococci, cocci
Oxygen relationship: aerobic bacteria
Motility: nonmotile
Catalase test: positive
Oxidase test: positive
Spores: non-spore forming
moraxella image

Moraxella (Branhamella)

Gram stain: Gram-negative
Microscopic appearance: diplococci, cocci, cocobacilli
Oxygen relationship: aerobic bacteria*
Motility: nonmotile
Catalase test: positive
Oxidase test: positive
Spores: non-spore forming
* some facultatively anaerobic
bordetella image

Bordetella

Gram stain: Gram-negative
Microscopic appearance: small rods or cocobacilli
Oxygen relationship: aerobic bacteria
Motility: nonmotile or motile
Catalase test: positive
Oxidase test: positive
Spores: non-spore forming
haemophilus image

Haemophilus

Gram stain: Gram-negative
Microscopic appearance: small pleomorphic rods
Oxygen relationship: facultatively anaerobic bacteria
Motility: nonmotile
Catalase test: variable
Oxidase test: variable
Spores: non-spore forming
pseudomonas image

Pseudomonas

Gram stain: Gram-negative
Microscopic appearance: rods
Oxygen relationship: aerobic bacteria
Motility: motile (rarely nonmotile)
Catalase test: positive
Oxidase test: positive or negative
Spores: non-spore forming
enterobacteriaceae

Enterobacteriaceae
E.coli, Salmonella, Klebsiella, Enterobacter, Proteus, Serratia, Yersinia

Gram stain: Gram-negative
Microscopic appearance: rods
Oxygen relationship: facultatively anaerobic bacteria
Motility: motile (peritrichous flagella) or nonmotile
Catalase test: positive
Oxidase test: negative (with exception of Plesiomonas spp.)
Spores: non-spore forming
ACID-FAST BACTERIA
mycobacteria

Mycobacterium

Gram stain: - (acid - fast)
Microscopic appearance: rods; sometimes cocobacilli or filaments
Oxygen relationship: aerobes
Motility: nonmotile
Catalase test: positive
Oxidase test: negative
Spores: non-spore forming
NON GRAM-POSITIVE/NEGATIVE
borrelia image

Borrelia

Gram stain: Not classified as either Gram-positive or Gram-negative
(the cells stain a weak Gram-negative)
Microscopic appearance: Spirochetes
Oxygen relationship: microaerobic
Motility: motile
Catalase test: -
Oxidase test: -
Spores: non-spore forming
bacterial colonies on agar bacterial colonies on agar bacterial colonies on agar bacterial colonies on agar
 
Colonies of pneumococci on agar Colonies of Mycobacterium tuberculosis on agar Colonies of Neisseria meningitidis on agar Colonies of Haemophilus influenzae on agar
 
 
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