Transcript Waterborne Pathogen Prevention and Detection Using Traditional

Waterborne Pathogen Prevention
and Detection Using Traditional
Methods and Microarray Probe
Detection
Claribel Orellana
CE 421
12/5/07
Biotechnology
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Priorities: Agriculture and Medicine
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Malaria Vaccine
Stem cell research
Completion of the human genome map
‘Golden Rice’ modified to make vitamin A
GCSF for increasing white blood count in chemotherapy patients
World Concern: Water Quality
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Half the world affected by contaminated water
Unsanitary conditions and lack of resources
Cause: waterborne pathogens
Waterborne Pathogens
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Three different types: bacteria, viruses, and bacteria
Name of micro-organisms
Major diseases
Major reservoirs and primary sources
Salmonella typhi
Typhoid fever
Human feces
Salmonella paratyphi
Paratyphoid fever
Human feces
Vibrio cholera
Cholera
Human feces and freshwater zooplankton
Enteropathogenic E. coli
Gastroenteritis
Human feces
Yersinia enterocolitica
Gastroenteritis
Human and animal feces
Legionella pneumophila and
related bacteria
Acute respiratory illness
(legionellosis)
Thermally enriched water
Giardiasis (gastroenteritis)
Water and animal feces
ascariosis
Animal and human feces
Bacteria
Protozoa
Giardia lamblia
Helminths
Ascaris lumbricoides
Typical Contamination
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Unprotected water source
Inadequate sanitation
Animal and fecal matter reaching water source
Surface runoff through the ground, water pipes and wells
Well
Cattle pond
Well
Surface drain
Cattle pond
Typical Contamination
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Animal and fecal matter reaching water source
Surface runoff through the ground, water pipes and wells
Traditional Practices for Safe Water
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Point-of-use disinfection
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Use of sodium and calcium hypochlorite
• Safer and easier to use and distribute
• Destroys most pathogens
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Electrolysis
• System run on solar power
• Generators can generate enough disinfectant for 10,000 people.
• Inexpensive
Traditional Practices for Safe Water
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Safe Storage
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Stored water vs. municipal tap
Container comparison
• CDC container
• Cantero
DNA Microarrays
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DNA microarrays: reverse dot-blots for which sequencespecific “probes” are attached to substrate in a lattice
pattern
spots are usually 100-200 micrometers and 200-500
micrometers away from each other and they represent
specific probe sequences
Simultaneous detection vs. cultivation
Polymerase Chain Reaction (PRC)
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PCR amplifies DNA sequences
Microarray Process
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Sequences are hybridized
Specific bacterial targets are detected
Precision Factors
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Assay sensitivity
• Sample size
• Efficiency of pathogen isolation
• Efficiency of nucleic acid extraction
• Effect of co-precipitating factors that inhibit PCR
Benefits and Limitations
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Benefits:
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Simultaneously detects pathogens
Not limited to identification by product length
Limitations:
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Requires pathogens to be identified before configuring array
Needs to be validated
Currently more expensive than traditional methods
Microarray Flow Process
Application
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EPA looking into feasibility
• Is being monitored
• Will most likely become a standard
• Soon be more cost-effective
• Priority is quick pathogenic detection