Waterborne Pathogen Prevention and Detection Using Traditional Methods and Microarray Probe Detection

1
Waterborne Pathogen Prevention and Detection
Using Traditional Methods and Microarray Probe
Detection

• Claribel Orellana
• CE 421
• 12/5/07

2
Biotechnology

• Priorities Agriculture and Medicine
• 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

3
World Concern Water Quality

• Half the world affected by contaminated water
• Unsanitary conditions and lack of resources
• Cause waterborne pathogens

4
Waterborne Pathogens

• Three different types bacteria, viruses, and
  bacteria

Name of micro-organisms Major diseases Major reservoirs and primary sources
Bacteria Bacteria Bacteria
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
Protozoa Protozoa Protozoa
 Giardia lamblia Giardiasis (gastroenteritis) Water and animal feces
Helminths Helminths Helminths
 Ascaris lumbricoides ascariosis Animal and human feces
5
Typical Contamination

• 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
6
Typical Contamination

• Animal and fecal matter reaching water source
• Surface runoff through the ground, water pipes
  and wells

7
Traditional Practices for Safe Water

• Point-of-use disinfection
• Use of sodium and calcium hypochlorite
• Safer and easier to use and distribute
• Destroys most pathogens
• Electrolysis
• System run on solar power
• Generators can generate enough disinfectant for
  10,000 people.
• Inexpensive

8
Traditional Practices for Safe Water

• Safe Storage
• Stored water vs. municipal tap
• Container comparison
• CDC container
• Cantero

9
DNA Microarrays

• DNA microarrays reverse dot-blots for which
  sequence-specific 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

10
Polymerase Chain Reaction (PRC)

• PCR amplifies DNA sequences

11
Microarray Process

• Sequences are hybridized
• Specific bacterial targets are detected

12
Precision Factors

• Assay sensitivity
• Sample size
• Efficiency of pathogen isolation
• Efficiency of nucleic acid extraction
• Effect of co-precipitating factors that inhibit
  PCR

13
Benefits and Limitations

• Benefits
• Simultaneously detects pathogens
• Not limited to identification by product length
• Limitations
• Requires pathogens to be identified before
  configuring array
• Needs to be validated
• Currently more expensive than traditional methods

14
Microarray Flow Process
15
Application

• EPA looking into feasibility
• Is being monitored
• Will most likely become a standard
• Soon be more cost-effective
• Priority is quick pathogenic detection