Food Borne Pathogens Flashcards
List Gram negative bacteria
Neg sal crok sleeps yvv Salmonella spp. Campylobacter spp. Verocytotoxigenic Escherichia coli Shigella spp. Yersinia enterocolitica Vibrio spp.
List Gram positive bacteria
POS lee shorr became Carter cartered Listeria monocytogenes Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus cereus
What are the ways we can get disease from food borne routes?
- through eating and/ or drinking
1. INFECTION
2. INTOXICATION
What are the different types of category of food borne infections?
Summaries each
- Toxico infection
Usually short incubation
TOXINS
a) Enterotoxin - produce toxins in the GUT. Pathogenic potential is local to gut and CS associated with gastrointestinal vom or diarr
b) neurotoxin - more dangerous than enteric, associated neurological signs - Invasive Infection: Usually long incubation period
Not toxins but bacteria
a) enteric - local
b) systemic - spreads systemically, more severe as can lead to bacteraemia and septicaemia
What are the different categories of food borne intoxications? (3)
- chemical
- Poisonous plants/ animals
- Microbial
Talk about microbial intoxication
- fungi
- bacteria (mycotoxins): diarrhoeic, enterotoxins or neurotoxins
- Algal (biotoxins)
Food borne intoxication vs foodborne infection
FB intoxication - organism produced specific toxins or toxic metabolites in the food that is INGESTED. TOXIN is ingested.
FB infection is either INVASIVE ( Bacteria ingested through food consumption, the organism invades and penetrates intestinal mucosa, NO TOXIN) or TOXICO infection (bacteria ingested through food consumption, the organism produces toxin while in the INTESTINAL tract)
examples of food borne intoxication
REmember when the organism produces specific toxins or toxic metabolite(s) in the food that is ingested
• Cl. botulinum intoxication in adults;
• Staph. aureus heat stable enterotoxin, - typical intoxication
• B. cereus (emetic syndrome)
Examples of food borne infection
- invasive - • Bacteria ingested through food consumption, the organism invades and penetrates intestinal mucosa: NO TOXINS
– Local enteric infection (non-typhoid Salmonella, Shigella, Campylobacter, Yersinia)
– Systematic infection (typhoid Salmonella, Listeria monocytogenes) - Toxico infection - • Bacteria ingested through food consumption, the organism produces toxin while in the intestinal tract:
– E. coli
Definition of facultative anaerobe
and examples gram neg ones?
grow in anaerobic conditions with a little oxygen e.g. • Salmonella spp. • Yersinia enterocolitica • E. coli O157 (and other VTEC) • Shigella spp. • Vibrio spp
NOT
• Campylobacter spp. (micro-aerophilic) – needs v low presence oxygen (5-7%) high presence CO2
Which bacteria causes YERNINIOSIS?
Main one
Yersinia
mainly Yersinia enterocolitica
List the 3 main species yersinia
- Yersinia enterocolitica - most common, more than 90% FB diseases caused by this
b. Y. pseudotuberculosis foodborne pathogens
c. Yersinia pestis – Bubonic plague (“black death”) NOT food borne. Not talk today
Growth characteristics Yersinia
- Gram negative,
- non-sporogenic,
- curved shaped rods
- Enterobacteriaceae = primary source guts, get into environment from gut and infect other animals
- Facultatively anaerobic rods (partial anaerobic atmosphere conditions)
- usually motile at 22-25 С° non motile higher
• PSYCHROPHILIC bacteria - grow Temp. range 1o – 44oC (28-29oC optimal)
• Salt: can grow 5-7% NaCl (high)
• Sustain v low pH 4
How common is Yerniniosis in the UK and EU??
• 3rd most common FB disease eu
- less common in UK due to main meat source being tongue and head muscles which aren’t preferred in UK meat market. And if meat is fully cooked then hard to get FB disease. High prevalence in pork in abattoir but we cook it a lot!
What are the diff parts to a hazard risk assessment?
hazard identification, incidence and exposure assessment
Infection route to humans of Yersinia enterocolitica
common in the throat, tonsils and faeces of pigs,
● but is also found in water, soil and dogs.
● The most important source are pigs!
● RAW, MINCED PORK !!!
● Direct transmission via faecal-oral route, and asymptomatic carriers animals are asympatomatic!
Disease caused by Yersiniosis
- Acute disease with fever and gastroenteritis, sometimes with bloody diarrhoea
- Infectious dose probably less than 104 cells
- Incubation short 1-11 days (1-1.5 day)
- Acute fase: Gastroenteritis
Lymphadenitis (mesenterial) - enlarged lymph nodes in the membrane that connects your bowel to the abdominal wall
Pseudo-apendicitis – pain right lower abdomen, resembles apendicitis
Septicemia serious
Liver, and other, abcesses
• Secondary complications (1-3 weeks later)
Arthritis
Erythema nodosum - inflammation subcut fat
Myositis - muscle inflammation
What priducts can get yersinia bacteria from?
- pigs and pork
- cattle and beef products
- Milk and milk prodcuts
- vegetables
- others inc D&C, rodents, water, pond, lake
Control measures yersinia PRE HARVEST
- PH is all events that take place on farm and in market
- Prevention of introduction of Y. enterocolitica within the farm
- Prevention of spread: biosecurity
- Stress management, genotype resistance
Biosecurity:
• Hygienic husbandry;
• Identification and removal of seropositives from the herd;
• Clean water, prevention of faecal contamination of water and feed – will also work for salmonella and campylobacter
CONTROL MEASURES IN THE HARVEST PHASE:
Events including transport, lairage (slaughter hosue depot), slaughter and dressing carcass
- Pig categorisation according to the risk they pose, before slaughter:
- Pigs originated from controlled herds?
- Seropositives, slaughter at end of day (problem is unstable immune response)
Slaughter and dressing, meat inspection - Head removal before carcass splitting and removal of the tongue – hygienic transfer to separate line for further handling and inspection to avoid cross contamination
- Avoid palpation and incision during inspection
- Tying the rectum to avoid gut spillage on carcus
CONTROL MEASURES IN THE POST-HARVEST PHASE:
Events including transport, distribution meat, cutting, secondary processing, tertiary processing (meat to gamon), prep of food, we are included in this too!
- Maintaining cold chain (once carcass chilled enter cold temp until moment of consumption) (potential problem due to psychrotrophic nature so even though cold temp is Y present in meat it will grow in fridge and may infect)
- Pasteurize milk and dairy products
- Cross-contamination → Keep Raw pork separate from other foods
- Proper cooking regime (72oC - 2-3 mins) gets rid of all vegetive forms bacteria only spore forming bacteria won’t be killed (clostridium and bacilli)
- Personal hygiene
- Cleaning and disinfection
How do we test for yersinia bacteria from pig?
remove tonsils and slash, plate onto CIN agar grow like a bulls eye
