1. DISTINGUISHING PATHOGENIC ORGANISMS

2. Pathogenic organisms can be macroscopic or microscopic
Macroscopic organisms: can be seen with the unaided eye
Microorganisms: cannot be seen with the naked eye
Pathogens: any organism that causes a disease
Most pathogenic organisms are microscopic or just barely visible to the unaided eye
Microscopic organisms include:
Bacteria
Viruses
Fungus
Parasites

3. Bacteria Cocci: spherical-shaped (ex: Streptococcus)
Bacilli: rod-shaped
(ex: Clostridium)
Spirilli: spiral-shaped
(ex: Treponema)

4. Virus Can be seen with an electron microscope Contain DNA or RNA
Use the host cell to replicate
Examples:
Hepatitis
Human papillomavirus (wart virus)
Hantavirus (Korean hemorrhagic fever virus)

5. Fungi (Mycology) Microscopic
Approximately 100 species are human pathogens
Infects humans by inhalation or inoculation
Examples:
Yeast-Candida albicans
Dermatophytes-Tinea capitis
ringworm of the scalp

6. Macroscopic Organisms
Parasite examples:
Cestodes: Pork tapeworm
Ex: Taenia solium
Nematodes: Pinworm
Ex: Enterobius vermicularis
Trematodes: Intestinal flukes
Ex: Clonorchis sinensis