 Unicellular


May not always appear as single cells able to communicate with one another through a process called quorum sensing.
 they can function as a multi-cellular population rather than as individual bacteria.
 Often found in clumps, groups or chains
 Identified and named by

Their shapes

The way they appear in groups

 Most bacteria are one of three shapes
(although there are a few other possibilities):
 Spherical
 Rod Shaped
 Spiral



 are spherical

(coccus = a berry)

Chains
Streptococcus & Staphylococcus
Grape-like Clusters

Scanning Electron Micrograph of
Streptococcus pneumoniae
Image provided by Dr. Richard Facklam .
Courtesy of the Centers for Disease Control and Prevention.



 bacillus (sing.) bacilli (pl.)
◦ are rodshaped
(bacill(um) = a little stick)

Appear in chains after division






Caption:-- Vibrio cholerae - curved (vibrioshaped), rod prokaryote; causes Asiatic cholera.

Caption:-- Neisseria gonorrhoeae - Gram-negative, coccus prokaryote (dividing); causes gonorrhea.

Caption:-- Streptococcus pyogenes - Gram-positive, coccus prokaryote (dividing). Causes pharyngitis, food poisoning, puerperal fever (childbed fever), scarlet fever, rheumatic fever, skin and wound infections (erysipelas, impetigo) . Group A Streptococcus.

Caption:-- Staphylococcus aureus -Gram-positive, MRSA, coccus prokaryote (dividing); causes food poisoning, toxic shock syndrome and skin and wound infections such as scalded skin syndrome, scarlet fever, erysipelas and impetigo.

Image provided by Joyce Ayers.
Courtesy of the Centers for Disease Control and Prevention

Staphylococcus albus

Streptobacillus nicolau

Gaffkya tetragena

Diplococcus pneumoniae

Spirillum minus

Scientific Name Disease and Body Part Affected
Diplococcus pneumoniae
Neisseria meningitides
Corynebacterium diphtheriae
Bordetella bronchiseptica
Clostridium tetani
Myobacterium tuberculosis
Staphylococcus epidermidis
Pneumonia—lungs
Meningitis--brain and spinal cord
Diptheria—nasopharynx or skin
Bronchitis—respiratory tract
Tetanus-nervous system (lock jaw)
Tuberculosis--lungs
Staph Infection—Skin & Mucous
Membranes
Bordetella pertussis Pertussis/Whooping Cough--Lungs

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