Exam 2

Question 1

what family is salmonella a part of?

Answer 1

enterobacteriaceae

Question 2

stain shape and respiration of salmonella

Answer 2

gram-negative, motile, rod-shaped, facultative anaerobe, uses respiratory and fermentative pathways

Question 3

what antigens does salmonella have?

Answer 3

O (surface) and H (flagellar)

Question 4

what are the two primary species of salmonella?

Answer 4

S. bongori & S. enterica
S. bongori has 1 subspecies which is subspecies V
S. enterica has 6 subspecies w/most human pathogens being in subspecies 1

Question 5

nontyphoidal vs typhoidal salmonella (enterica 1)

Answer 5

typhoidal: humans, typhoid fever, paratyphoid fever, usually where people congregate
nontyphoidal: humans and animals, gastroenteritis and extraintestinal

Question 6

salmonella history

Answer 6

associated with poor sanitation/hygiene, typhoid mary carrier and chronic shedder cooked for multiple households in 1900s

Question 7

typhoidal salmonella

Answer 7

s enteria, causes typhoid and paratyphoid fever, restricted growth in humans

Question 8

nontyphoidal salmonella

Answer 8

causes disease in animals and humans, transmission from animal to person or food

Question 9

how does salmonella create an infection

Answer 9

adheres and invades (unlike ecoli) intestinal epithelial cells in terminal portion of small intestine bacterial cells internalize and multiply cause inflammatory response,
pathogenicity island 1 aids in invasion then type 3 secretion system delivers virulence factors, pathogenicity island 2 allows bacteria to multiply
produce toxins which cause an immune response in host

Question 10

salmonella pathogenicity island 1 (SPI-1)

Answer 10

aids with entry into intestinl epithelium, enables pathogen to exploit host intestinal environment

Question 11

salmonella pathogenicity island 2 (SPI-2)

Answer 11

intracellular replication and initiation of systematic infection

Question 12

type III secretion system (TTSS)

Answer 12

main way salmonella delivers virulence factors to host, needle structure extended by protein base forms a channel to host

Question 13

salmonella containing vesicle & purpose

Answer 13

after ingestion salmonella enters a SCV through bacteria-mediated endocytosis, salmonella lives and multiplies in SCV = a method to avoid host immune response

Question 14

what is salmonella main virulence factor and its effect

Answer 14

SopB, an enterotoxin associated with SPI-1 TTSS, induces an increase in concentration of inositol polyphosphate
water follows to balance osmolarity which will cause diarrhea = first virulence factor, will then lead to dehydration

Question 15

where does salmonella come from

Answer 15

widely found in GI tracts of domestic and wild animals
livestock species, pets (turtles), pests, birds (harder to find in cattle and pig)
salmonella can cause illness in some livestock species unlike ecoli

Question 16

how does salmonella get into meat

Answer 16

contamination occurs via the same mechanisms as ecoli contamination
cross contamination during processing/hide removal or within raw products, poor sanitation during processing

Question 17

have samonella cases decreased throughout the years

Answer 17

no there has even been a slight increase, 2000 - 2011 have seen a 17% increase

Question 18

salmonella serovar (types) in US

Answer 18

there are many strains that can be found across livestock species and we are even finding new ones that have not been identified previously

1/4 of all outbreaks we can’t identify

Question 19

salmonellosis (dosage, incubation, symptoms, duration)

Answer 19

generally requires large infection dose (unlike ecoli) incubation period of 8 to 48 hrs, causes diarrhea, nausea, abdominal cramps, fever
duration of 3 - 7 days
self-limiting and usually resolve themselves

Question 20

salmonella foodborne illness

Answer 20

most common bacterial foodborne illness ~34% illness in US, associated with multiple foods 20% poultry, 14% beef & pork, 57% produce eggs etc
>1 million illness & 450 deaths annually (prob more because people don’t report)

Question 21

prevalence of salmonella in poultry

Answer 21

less in young chicken (4.2%) vs ground chicken (28%)

Question 22

salmonella mitigation

Answer 22

control on the farm through pest control, biosecurity, environmental control (sanitizing barns water air)

Question 23

process controll salmonella mitigation

Answer 23

sanitary processing, eliminating cross contamination

Question 24

pre & post-harvest interventions

Answer 24

pranic acids, vaccines, direct-fed microbials, process interventions

Question 25

what are challenges of salmonella control

Answer 25

salmonella is evading current surface interventions, it is an internalized bacteria and in pultry parts w/ bones and lymph nodes, antimicrobial resistance

Question 26

monitoring Salmonella, who and how

Answer 26

FSIS, monitors pathogen reduction/HACCP systems, sets performance standards, only manage what you measure

Question 27

Listeria genus and species

Answer 27

Listeria genus includes 10 species with only L.monocytogenes being human pathogen

Question 28

listeria environmental pathogen and natural resivors

Answer 28

soil, water, GI tract, human carriers, pests, silage is vector

Question 29

why is listeria unique?

Answer 29

is intracellular and passes from cell to cell, can penetrate brain and placenta

Question 30

pathology of listeria (steps of infection)

Answer 30

L.mono enters through GI, interacts with GI (internalin-A & E-cadherin), cross epithelial layer via vacuole, resides in vacuole until lysed by listeriolysin, LLO toxin creates pores in host cell membranes, listeria multiplies, forms tail

Question 31

exposure vs infection

Answer 31

exposure to L.mono is common, listeriosis is rare, less than 1% foodborne illness but 30% foodborne deaths
most in high risk groups: pregnant, newborns, immunocompromised

Question 32

listeriosis incubation period and difficulty

Answer 32

incubation period ranges from 2-3days to 3-5 weeks making it hard to track, also first symptoms are flu-like then progress making it hard to catch

Question 33

why is listeria problematic in food industry

Answer 33

can persist and grow in many environments and isn’t effected by same interventions that are used to kill ecoli etc in meat processing
tolerance to cold temps, moisture, salt concentrations

Question 34

introduction of listeria in food

Answer 34

can be from contaminated animals, contaminated equipment, cross-contamination by employees (interventions in processing will work but after employee can still introduce)

Question 35

listeria and RTE foods

Answer 35

zero tolerance policy for L.mono in RTE foods
contamination can occur post-processing, survive in product environment

Question 36

Listeria monocytogenes biofilms

Answer 36

listeria grows and matures in biofilm before dispersing, they tend to grow in hard-to-reach areas within plant and are less susceptible to cleaning

Question 37

controlling listeria in RTE meats

Answer 37

must comply with one of the following:
1. use post-lethality treatment AND antimicrobial agent
2. use post-lethality treatment OR antimicrobial agent
3. use sanitation measures only

Question 38

campylobcateer basics

Answer 38

gram negative, s-shaped, non spore forming, obtain energy from amino acids, highly motile with flagella on one or both ends

Question 39

campylobacter basic environment

Answer 39

microaerophilic (3-5% O2, 2-10% CO2) makes culturing difficult, prefer water activity (high moisture food w/ little salt), 37 and 42C (incapable of growth 30C) commonly carried in animal GI tract

Question 40

campylobacter species

Answer 40

numerous species implicated in human illness, campylobacter jejuni & campylobacter coli are most common
campylobacter fetus - spontaneous abortion in cattle and sheep)

Question 41

campylobacter pathology

Answer 41

little is known of pathology, flagella aid in colonization of SI, once colonized releases cytotoxins DCT, survive by chemotaxis since acidic gut environment not conductive,

Question 42

campylobacteriosis

Answer 42

onset of disease range from 1-10days, symptoms for 3-6 days, death extended illness is rare

Question 43

campylobacter epidemiology

Answer 43

14/100,000 people affected each year, 1/3 associated with poultry, rising number from raw milk

Question 44

campylobacter & poultry

Answer 44

birds are natural reservoirs and asymptomatic carriers, greater risk with greater volume
prevalence varies by productive system flocks range from 2-100%, organic and free range have higher prevalence, once positive difficult to eliminate without depopulation b/c vertical integration

Question 45

controlling campylobacter

Answer 45

begins at farm, sanitation, biosecurity, probiotics, feed acidifcation

at plant, segregation of positive flocks, regular monitoring to reduce cross-contamination