Classes of
Microorganisms
2.02 Understand infection control
procedures
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Classes of Microorganisms

Non-pathogenic
– normal
– do not produce disease
– beneficial

Pathogenic
– cause infection and disease
 May be non-pathogenic in one body system,
pathogenic in another (E. coli)
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Classes of Microorganisms

Aerobic
– requires oxygen to live

Anaerobic
– does not require oxygen to live
2.02 Understand infection control
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Classes of Microorganisms

6 classes of microorganisms
– Bacteria
– Protozoa
– Fungi
– Rickettsiae
– Viruses
– Helminths
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Classes of Microorganisms

Bacteria
 Often considered the causes of disease
 Certain bacteria
– produce antibiotics
– live in the body without problems
– live on the roots of certain plants,
converting nitrogen into a usable form
– help break down dead organic matter

Classified by shape and arrangement
 Treated with antibiotics
2.02 Understand infection control
procedures
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Classes of Microorganisms

Bacteria
– Cocci round in shape
– diplococci
– streptococci
– staphylococci
Streptococci
Staphylococcal clusters
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Classes of Microorganisms

Bacteria
– Bacilli
 rod shape
– single
– pairs
– chains
 may have flagella
 may form spores
– difficult to treat
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Classes of Microorganisms

Bacteria
– Spirilla
 spiral or corkscrew shape
– vibrio
- spirochete
Cholera
Treponema pallidum
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procedures
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Classes of Microorganisms
Bacteria
 Some bacteria develop resistance to
antibiotics
 Very difficult to cure

– Methicillin-resistant Staphylococcus (MRSA)
– Multidrug-resistant Staphylococcus (MDSA)
2.02 Understand infection control
procedures
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Classes of Microorganisms

Protozoa
– One celled, animal-like organism
– Contain a nucleus and other defined
organelles
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Classes of Microorganisms

Fungi
– organisms that usually enjoy a symbiotic, but
sometimes parasitic relationship with their host
– provide numerous drugs and foods
– provide bubbles in bread, champagne, and beer
– cause a number of plant and animal diseases
– fungal diseases are very difficult to treat
2.02 Understand infection control
procedures
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Classes of Microorganisms

Fungi
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Classes of Microorganisms

Rickettsiae
– rod-shaped, parasitic
bacteria
– live in the tissues of ticks,
fleas, and lice
– transmitted to humans
through bites
– invade the new host from
within
2.02 Understand infection control
procedures
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Classes of Microorganisms

Viruses
– small, infectious agent
– requires a host for survival
– over 5,000 types
– can combine in multiple ways to produce a
wide range of diseases
– produce immune response in humans
– treated with antiviral drugs
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Classes of Microorganisms

Helminths
–
–
–
–
–
–
Parasitic worm-like organisms
Live inside the host
Feed off their host
Disrupt nutrient absorption
Lead to weakness
Excrete toxins making host
susceptible to other diseases
– Approximately 30 billion people
globally are infected
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Classes of Microorganisms
Bacteria
 Protozoa
 Fungi
 Rickettsiae
 Viruses
 Helminths

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