General Water Microbiology

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General Water Microbiology

• Robin Cook

FSEA Fall Meeting and Technical Session 10/17/2007
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Introduction

• Why we do this matters!
• How we do this matters!
• This is not just about meeting a regulatory
  requirement.

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Overview

• What are we looking for?
• Why are we looking?

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Vocabulary

• Coliform Bacteria Gram (-),non-spore-forming,
  facultative anaerobic, rod-shaped bacteria
  capable of growth in the presence of bile salts
  and that ferment lactose with production of gas,
  acid and aldehyde within 48hrs at 35C.
• OR Coliform Bacteria possessing the enzyme
  ?-galactosidase which cleaves ONPG resulting in a
  release of a chromogen.
• These definitions are operational rather than
  taxonomic and therefore tied to a method as well.

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Vocabulary cont.

• This definition includes Enterobacter aerogenes
  which is NOT typically associated with the
  intestine.
• Depending on which defintion Serratia may or may
  not be a coliform. Not all species will ferment
  lactose.

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Vocabulary Cont.

• Coliforms are members of the enteric bacteria
  group also know as the Enterbacteriaceae family.
• Fecal Coliforms are further defined as
  thermotolerant coliforms capable of growth with
  acid and gas formation at 44.5ºC.

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Enterobacteriaceae Family

• Klebsiella, Enterobacter, Citrobacter, and
  Escherichia are classified as coliforms.
• Escherichia coli, Citrobacter freundii and
  thermotolerant Klebsiella pneumoniae are
  classified as fecal coliforms.
• Non-coliforms include Proteus, Serratia
  (depending), Yersinia, Shigella, and Salmonella.
  These are excluded only because they do not
  usually ferment lactose.

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Other indicators

• Fecal Streptococcus Gram () bacteria which is a
  normal inhabitant of the GI tract of warm-blooded
  animals.
• Only a few are pathogenic
• Persist well, but do not reproduce in the
  environment.
• Many isolates are not associated with humans.

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Other indicators cont.

• Enterococcus subgroup of the Fecal
  Streptococcus
• can grow in 6.5 NaCl, at pH 9.6 and at both 10ºC
  and 45ºC.
• Used to check quality of recreational waters

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Interesting Trivia

• Ratio of FCFS
• FCFS gt 4.0 human contamination
• FCFS lt 0.7 animal contamination
• Between suggests a mixed source
• Only valid in the 1st 24 hours, and technology
  dependent

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Concerns and Disease

• Klebsiella opportunistic pathogen. Can cause
  infection in wounds, soft tissue and urinary
  tract as well as pneumonia in immuno-compromised.
  
• Enterobacter, Citrobacter, and Serratia mostly
  hospital-related infections
• Serratia is particularly prevalent in maternity
  wards
• E. coli septiciema, UTI, neonatal meningitis,
  gastroenteritis and hemorrhagic colitis.
• Proteus UTI and contributes to the formation of
  kidney stones due to pH change it causes.

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Continued

• Yersinia septicemia, enterocolitis, Bubonic
  Plague.
• Shigella gastrointeritis
• Salmonella typhi Typhoid Fever
• Not in the family but grows in the same
  conditions Vibrio cholerae which is what causes
  cholera in untreated water.

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Indicator Organisms

• Associated with the intestinal tract typically in
  large numbers
• Found in warm-blooded animals as well as humans
  yet will die once excreted
• Death-rate is similar to the pathogenic
  Salmonella and Shigella
• Both coliforms and pathogens react in a similar
  manner during the water purification process.

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Summary

• The presence of coliforms indicates a problem
• BUT, absence does not necessarily mean that there
  is not a problem
• Need as much information as possible to make a
  good decision.

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References

• Brock, Thomas D. et al. Biology of
  Microorganisms 7th ed. Englewood Cliffs, NJ
  Prentice Hall, 1994.
• Cullimore, D. Roy. Practical Manual of
  Groundwater Microbiology. Boca Raton, FL
  Lewis, 1993.
• Murry, Patrick R., et al. Medical Microbiology
  2nd ed. St Loius, MO Mosby, 1994.

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Any questions?