Bacteria: Kingdom Prokaryotae (Monera)
No organized nucleus
Single-celled organisms; are ubiquitous in nature
Amplification (growth) by an increase in number of cells, not by an increase in size
Can demonstrate classic exponential growth
Ex: Legionella pneumophila, (a gram-negative, aerobic bacillus) responsible for Legionnaires’ disease, Pontiac fever
Cooling towers, fountains, hot tubs, building water systems
See ASHRAE Guideline 12-2000: Minimizing the Risk of Legionellosis Associated with Building Water Systems
Other Gram-negative bacilli (rod-shaped)
Endotoxin: cell wall component
Heat-stable molecule – not eliminated by autoclaving
Highly toxic: Gram-negative bacterial infection produces fever, malaise, changes in white blood cell counts, respiratory distress, shock
Acute and chronic inhalation effects include airflow obstruction, accelerated loss of lung function
Gram-positive bacilli
Prevalent in soil, water, air and vegetation
Spore-bearing; spores resistant to environmental stress
Most are non-pathogenic (do not cause disease)
Exception: Bacillus anthracis, responsible for anthrax
Spores are 1 - 1.5 microns in size
Transform into reproducing bacilli in chest lymph nodes
Release toxins that cause septic shock and respiratory failure
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