Important Bacterial Groups in Microbiology
Bacterial Group
Spirochetes
Characteristics
Long, thin, helical cells.
Movement by axial filaments.
Enterics
Facultatively anaerobic (can live without oxygen,
(Family
otherwise grows with oxygen). Grows in human
Enterobacteriaceae)
intestinal tract
Gram negative aerobic rods Rod and coccus shapes, lives in soil, water, and
and cocci
are parasites of animals. Lives only in the
presence of oxygen.
Rickettsias and chlamydias Obligate intracellular parasites.
Rod shaped but variable in form.
Mycoplasmas
No cell walls (no murein, but plasma membrane
still present).
Gram positive cocci
Gram positive, some resistant to penicillin, Some
hemolytic (can break red blood cells)
Example bacteria in this group
Leptospira (causes leptospirosis)
Treponema (causes syphilis)
Escherichia (in human colon)
Salmonella (causes food poisoning)
Shigella (causes shigellosis diarrhea)
Pseudomonas aeruginosa (infections)
Neisseria gonorrhoeae (gonorrhea)
Brucella (causes brucellosis)
Rickettsia prowazekii (typhus)
Chlamydia trachomatis (urethritis)
Mycoplasma pneumoniae (walking pneumonia)
Staphylococcus aureus (surgical infections, toxic shock);
Streptococcus pyogenes (sore throat/pharyngitis), S.
mutans (denal caries)
Endospore forming bacteria All gram positive rods and cocci.
Bacillus anthracis (causes anthrax)
Forms heat/chemical resistant endospores (hard to Clostridium tetani (causes tetanus)
kill by disinfection/heating).
Clostridium botulinum (causes botulism)
Mycobacteria
Thick, waxy material in cell wall, retains
Mycobacterium leprae (causes leprosy)
carbofusion dye in staining reaction ("acid fast"
Mycobacterium tuberculosis (causes tuberculosis)
stain).
Archaebacteria
Unusual cell walls of NAG sugar units.
Halobacterium (lives in salt marshes)
Often found in extreme environments.
Sulfolobus (lives in hotsprings)
Includes thermophiles, halophiles, acidophiles,
and methane producers.
Thermophiles hard to kill by heating.