Food Microbiology

Question 1

name the foodborne bacterial pathogen

most frequent cause of foodborne outbreaks; highest number of cases & hospitalisations

(eggs, egg products, mixed foods)

Answer 1

Salmonella

Question 2

name the foodborne bacterial pathogen

most frequently reported zoonosis;
most commonly reported GI pathogen in UK

(meat from chickens and turkeys)

Answer 2

Campylobacter

Question 3

name the foodborne bacterial pathogen

most deaths

(dairy, meat products, fish)

Answer 3

Listeria monocytogenes

Question 4

name the foodborne bacterial pathogen

(pork products, unoasteurised milk)

Answer 4

Yersinia enterocolotica

Question 5

name the foodborne bacterial pathogen

(minced meat, unpasteruised milk, leafy greens, bean sprouts, water)

Answer 5

Shiga toxin-producing E. coli

Question 6

name the 5 most common foodborne bacterial pathogens in the EU

Answer 6

1. Salmonella
2. Campylobacter
3. Listeria monocytogenes
4. Yersinia enterocolitica
5. Shiga toxin-producing E. coli

Question 7

name the 3 important EU food safety legislations

Answer 7

1. Regulation (EC) 852/2004 article 4
2. Reguation (EC) 2073/2005
3. Regulation (EU) 2017/625

Question 8

name the safe food legislation

gives defined limits on presence or number of microbes or their metabolites in food;
ensures food is produced hygienically and is safe for the consumer BUT cannot guarantee food safety

Answer 8

Microbiological Criteria for Foodstuffs

Regulation (EC) 2073/2005

Question 9

name the 2 types of criteria established in Regulation 2073/2005 (microbiological criteria for foodstuffs)

Answer 9

1. process hygiene criteria
2. food safety criteria

Question 10

what happens when a food safety criterion is not met?

Answer 10

batch of food should be removed from and not placed on market

Question 11

name the criteria established in Regulation 2073/2005

purpose for testing against this criteria is NOT to assess the fitness of individual carcases or processed meat for human consumption BUT to provide an indication of performance and control of the slaughter, dressing and production hygienic process at time of sampling;
applies to:
1. carcases
2. minced meat
3. meat preparations
4. mechanically separated met

Answer 11

process hygiene criteria

Question 12

this is a measure of bacteria in the sample that can survive in the conditions on the surface of carcases or in processed meat;
includes bacteria arising both from animals and from the slaughterhouse or meat processing environment

(requirement of process hygiene criteria)

Answer 12

Aerobic Colony Count (ACC)

Question 13

this is a grouping of bacteria that live in the intestines of animals and the environment
(includes E. coli and Salmonella)

Answer 13

Enterobacteriaceae

Question 14

name the criteria established in Regulation 2073/2005

these have been set out for fresh poultry meat, minced meat, meat preparations, meat products and mechanically separated meat;
if criteria are exceeded, the batch tested is unsatisfactory and should be removed from the market (or not placed on the market)

Answer 14

Food safety criteria

Question 15

demonstration of compliance with food safety criteria for meat and processed meat is required by the absence of Listeria monocytogenes in …

Answer 15

ALL ready-to-eat foods

Question 16

demonstration of compliance with food safety criteria for meat and processed meat is required by the absence of Salmonella in …

Answer 16

carcases/meat

Question 17

what is the only compulsory test for working surfaces when making ready-to-eat products under food safety criteria

Answer 17

for Listeria monocytogenes

Question 18

what species of Campylobacter is responsible for 90% of human enteric illness

Answer 18

C. jejuni

Question 19

name 5 conditions that Campylobacter is susceptible to

Answer 19

1. low oxygen
2. dessication
3. freezing
4. low pH
5. high temperature

Question 20

what is the biggest reservoir of Campylobacter causing human infections

Answer 20

poultry

Question 21

name 4 ways to control Campylobacter on-farm

Answer 21

1. improved biosecurity and hygiene
2. simple modification of diet (add organic acids or probiotics)
3. reduce slaughter age (33-35d)
4. discontinue thinning

Question 22

name 3 ways to control Campylobacter in the slaughter house

Answer 22

1. cleanliness of birds
2. good hygienic practices & HACCP throughout
3. accurate evisceration

Question 23

what is the most common species of Salmonella causing gastroenteritis

Answer 23

Salmonella enterica

Question 24

name 3 serovars of Salmonella enterica that cause disease

Answer 24

1. Typhimurium
2. Enteritidis
3. Newport

Question 25

# name the type of salmonellosis nausea, vomiting, abdominal cramps, diarrhoea, fever, headache

Answer 25

enteric salmonellosis

Question 26

# name the type of salmonellosis septicaemia; endemic to Africa, Asia, Central and South America; more a disease of poverty and poor hygiene conditions

Answer 26

Typhoidal salmonellosis

Question 27

what is the most common source of enteric salmonellosis infection?

Answer 27

poultry | (both meat and eggs)

Question 29

name 2 important aspects of control of Samonella

Answer 29

1. vaccine 2. Red Lion Code

Question 30

this is a notorious strain of shiga toxin-producing E. coli (STEC); causes mild diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome (HUS), thrombocytopaenia purpura

Answer 30

E. coli O157:H7

Question 31

what is the main reservoir for STEC; they are asymptomatic, super shedder individuals

Answer 31

cattle

Question 32

name 5 clinical signs of listerosis in humans

Answer 32

1. bacteraemia 2. septicaemia 3. meningitis, encephalitis 4. miscarriage 5. neonatal disease

Question 33

name the zoonotic foodborne virus (most foodborne viruses are not zoonotic)

Answer 33

Hepatitis E

Question 34

# name the foodborne virus most common cause of infectious intestinal disease in the UK; highly infectious and easily transmissible; can be transmitted through food, BUT majority of cases NOT foodborne; symptoms: vomiting, diarrhoea, headaches, abdominal pain, fever

Answer 34

norovirus

Question 35

# name the type of hepatitis virus those that are parenterally transmitted

Answer 35

'serum' hepatitis

Question 36

# name the type of hepatitis virus those transmitted through the faecal-oral route i.e. "enteric" hepatitis

Answer 36

"infectious" hepatitis

Question 37

name the 2 types of hepatitis virus that cause "enteric" hepatitis

Answer 37

1. Hepatitis A 2. Hepatitis E

Question 38

what animal is the biggest reservoir for Hepatitis E

Answer 38

pigs

Question 39

# name the method for bacterial food testing methods based on detection, isolation, characterisation and identification of microbes

Answer 39

qualitative methods

Question 40

# name the method for bacterial food testing methods based on the detection & enumeration of microbes (usually in liquid and/or agar material)

Answer 40

quantitative methods

Question 41

name the 5 steps of qualitative lab culture methods

Answer 41

1. sample collection 2. culture of samples in enriched broth 3. culture on selective media 4. confirmatory tests 5. examine identification tables

Question 42

# name the type of bacteriological agar non-selective, non chromogenic; most bacteria appear similar (white colonies)

Answer 42

Luria-Bertani Agar / Nutrient Agar

Question 43

# name the type of bacteriological agar non-selective; used for assessment of haemolysis (Clostridium perfringens); can grow a large variety of other more fastidious organisms

Answer 43

blood agar (sheep, horse)

Question 44

# name the type of bacteriological agar semi-selective; used for Salmonella and Shigella isolation; some Salmonella can metabolise thiosulphate - produces hydrogen sulphite and colonies turn black in the centre

Answer 44

xylose lysine deoxycholate (XLD) agar

Question 45

# name the type of bacteriological agar selective for enterobacteriaceae (due to bile salts); chromogenic: lactose fermenters appear pink/red (E. coli), non-fermenters appear white (Salmonella)

Answer 45

MacConkey agar

Question 46

# name the type of bacteriological agar selective for Campylobacter; have to be incubated in reduced oxygen (5%)

Answer 46

charcoal-cefoperazone-deoxycholate agar (CCDA)

Question 47

# name the rapid method of detection used to separate & concentrate target organism; 10 min procedure; specific Ab fixed on paramagnetic beads added to broth; binding of pathogen to Ab, magnet used to immobilise pathogen, removal of remainder

Answer 47

immunomagnetic separaton (IMS)

Question 48

# name the rapid method of detection firefly luciferin-luciferase; two-step biochemical reaction takes place, which produces light; most widely used for monitoring cleaned surfaces

Answer 48

ATP bioluminescence

Question 49

# name the rapid method of detection widely used in food testing; sensitivity varies; can be specific for pathogen at species and subspecies/strain level; can also detect toxins and allergens

Answer 49

ELISA (Enzyme Linked Immunosorbent Assay)

Question 50

# name the rapid method of detection can be very specific; can identify pathogen strain; multiple primers can be used at once to specifically ID more than one bacterial strain; degenerate primers can be used to ID multiple strains of same species but additional confirmatory tests needed afterwards

Answer 50

Specific Nucleic Acid Amplification / Detection (PCR)

Question 51

# name the rapid method of detection serum from immunised animals provides fast (2 min) and specific detection; bacterial cells cross link via surface antigens bound to antibodies in the sera; easily used for Salmonella type identification

Answer 51

serum agglutination