Food Borne Microbial Diseases Chapter 29

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Food Borne Microbial DiseasesChapter 29
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Food spoilage

• Organic material supports the growth of
  chemoorganotrophs
• Based on aw
• Perishable foods
• Semiperishable
• Stable/Nonperishable
• Growth Phase is variable

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Food Preservation

• Aims to slow growth or eliminate
• Cold vs. freezing
• Pickling (pH 5) addition of salt or sugar
• Drying
• Pasteurization Canning
• Additives sodium propionate, nitrites
• Irradiation

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Disease

• Food poisoning vs. Food infection
• Ex. Staphylococcal Food poisoning
  gastroenteritis in 1-6 hours
• 185,000 cases/year
• Antibiotics not helpful

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Clostridial Food poisoning

• C.perfringens (248,000 cases/year) and
  C.botulinum (6 cases/year)
• Sporulation in intestines, resolves in 24 hrs
• Botulinum neurotoxin respiration heartbeat
• Heat at 80C for 10 mins

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Food Infection

• Active infection due to ingestion
• Salmonellosis
• Fecal contamination
• 8-48 hrs after ingestion
• Chronic carrier state
• Resistant to several antimicrobials
• Food handlers banned from work until feces
  negative for 3 successive cultures

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Food Infection

• Pathogenic E.coli enterotoxins
• Enterohemorrhagic E.coli (EHEC) verotoxin
• Bloody diarrhea and kidney failure
• Other strains Travelers diarrhea
• Penetrating radiation required for ground meat
  avoid local water sources and uncooked food

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Food Infection

• Campylobacter
• C.jejuni, C.coli, C.fetus
• Normal flora of chickens and turkey
• Listeriosis
• L.monocytogenes Non-spore forming rod,
  psychotolerant and salt-tolerant
• Found in soil and water
• Culture from blood or spinal fluid
• Acute bacteremia and meningitis spontaneous
  abortion