Food Bact Exam 3

Salmonella enterica

Facultatively anaerobic

regular rods

oxidase negative

mesophilic infectious/ invasive pathogen of humans and animals

Salmonella enterica can ferment … but not, …

Salmonella enterica can ferment glucose but not lactose or sucrose; can use citrate as carbon source

some salmonellae are flagellated but some non-flagellated

true

Salmonella enterica is adulterated in…

Salmonella enterica is adulterated in RTE foods, fully cooked meat/ poultry (zero tolerance)

Salmonella enterica is identified by

CDC as #1 case of human foodborne bacterial disease

Salmonella enterica disease incidence

animal and plant derived and numerous serovars involved in differing outbreaks

Salmonella Taxonomy: species

S. enterica , S. bongori

Salmonella Taxonomy: S. enterica, sub-species

6 in total

enterica, arizonae, diarizonae are the main that are in human foods

Salmonella serovars are identified and differentiated by

O, H, K antigens

Salmonella Serovars

Serological identification rests on differentiation of somatic, capsular, and flagellar antigens

Reservoirs of salmonella

Livestock, poultry, water, plant derived- foods, companion animals

Salmonella optimal temp.

32-38C but low and high temp growth also exist

Prior cold, heat exposure can lead to adaptation of salmonella cell

true

no growth, but long term survival of salmonella in frozen foods

true

Salmonella can remain viable in…

dehydrated/ low aw foods for long time period, resisting heat application

Salmonella tolerance to acidity

pH 4.5

Salmonella alkali up to

pH 9.5 (optimal at neutral pH)

Mild acid shock can result in…

cross protection to subsequent heat exposure (chaperone proteins activated to protect DNA, RNA, other critical systems)

Foodborne Salmonellosis is typically caused by

non-typhoidal salmonellae: invasive pathogen

Foodborne Salmonellosis: Incubation period range

8-72 hr

Foodborne Salmonellosis w symptoms running…

2-7 days

Acute disease from foodborne salmonellosis is more common, but

fatalities occur (Reiter syndrome, reactive arthritis)

Typhoid Fever (Enteric Fever)

S. Typhi, Paratyphi A

Typhoid Fever incubation period

1 wk - 2 months, symptomatic state may persist 2-4 week

Typhoid fever can spike exceeding…

100F abdominal pain, severe diarrhea, and constipation (rash may occur)

Typhoid Fever: Asymptomatic carrier state can occur…

following decline of clinical symptoms

Non-Typhoidal Salmonella

Attachment of Salmonella to GI cells allows subsequent uptake into the GI cell (invasion)

GI cell membrane ruffles, resulting in…

endocytosis (invasion) of Salmonella into GI epithelials

Non-Typhoidal salmonella may be followed by…

Gi programmed cell death

Pathogen can also survive in

phagocyte acidic phagosome (membrane-bound small compartment entrapping Salmonella)

Siderophores

Vaccines for animals have targeted these surface located proteins

Shigella spp

Anaerobic mesophiles

regular rods

oxidase negatue

Shigella spp. is not able to use…

lactose

Shigella spp. is nearly…

identical to E.coli genetically

Shigella spp can cause…

human infectious disease : humans are the only reservoir of organism

Foodborne shigella

transmission via fecal/ oral route following poor personal hygiene

Shigella disease symptoms vary but generally include

severe diarrhea, heavy blood, and mucosal stool

Foodborne Shigella disease includes

watery diarrhea + pathogen colonization of colon leads to mucous cells sloughing off

Shigella Foodborne disease Infective dose

10- 200 cells

Shigella Foodborne disease can survive for..

long periods in frozen foods, allowing for distribution and retention of possible infectivity

Shigellosis: incubation & duration

8- 50 hr

duration 5-7 days

Shigellosis disease occurs most frequently in

younger children (<6)

Shiga toxin produced by isolates can produce

HUS

Shigellosis: Dysentery drives…

excessive GI colonization

Pathogenesis of Shigella

enterotoxin production by bacterium

Invasion capacity, similar to pathogenic E.coli

Incubation or organism at physiological temperature induces invasion capabilities

Prevention/ Control Shigellosis

proper cooking and good hygiene

Yersinia spp.

facultative anaerobe

zoonotic pathogen

oxidase negative

regular rod

oxidize/ferment glucose

Type species: Yersinia

Y. pestis (cause of bubonic, pneumonic plague)

Yersinia: Foodborne species of concern in food safety (2)

Y. enterocolitica

Y. pseudotuberculosis

Y. enterocolitica exhibits …… capacity with growth at …C and survival in…

psychrotophic, 4^°C , cooked foods enhanced over raw food

Cooking enhances nutrient utility to Yesinia organism

true

Yesinia is capable of growth from pH… with…. tolerance

4-10, alkali

Yersinia enterocolitica

most isolates are Voges-Proskauer+

Many isolates use D-xylose, trehalose but most cannot produce beta-D glucosidase

Yersinia enterocolitica: Many isolates use…., trehalose but most cannot produce …..

D-xylose, beta-D glucosidase

Yersinia enterocolitica: typing based on…

O-antigen and H-antigen profiles

Yersiniosis

typically acute diarrheal disease w higher incidences in young children <5 yrs

Yersiniosis: symptoms in young children

diarrhea, vomiting, fever, abdominal pain

Yersiniosis: symptoms in older children

symptoms mirroring appendicitis

Yersiniosis: infectious dose

104-106 cells

Yersiniosis: Incubation time

1-11 days post-consumption

Yersiniosis: clinical symptoms persist up to…

3 weeks

Yersiniosis: chronic… can occur, with reactive,,,,

sequelae, arthritis

Sources of pathogenic Yersiniae

Animal-derived foods, undercooked or raw (zoonoses)

Y.enterocolitica: popular food outbreak

milk

Yersinia: Pathogenesis elements

Invasive pathogen, similar to salmonella

enterotoxin production

Yersinia: Pathogenesis elements: Phospholipase production

hemolysis of blood cells

Yersinia: Pathogenesis Elements: Urease production

acid protection

Yersinia: Flagella

not produced in lab, but recovered from patients

6 CDC Yersiniosis preventions

dont consume undercooked/raw food

dont consume raw milk

wash hands

prepare chitterling carefully

use separate cutting boards for meat and produce

Chemical Food Antimicrobials Definitions: Chemical preservatives

when added to food, tends to prevent or retard deterioration

Chemical Food Antimicrobials Definition: Food Additives

intended use of which results or may reasonably be expected to result directly or indirectly in either becoming a component of food or otherwise affecting the characteristic of food

Chemical Food Antimicrobials Definition: Antimicrobial agents

substances used to preserve food by preventing growth of microorganism and subsequent spoilage, including fungistats, mold, rope inhibitors

who regulates antimicrobial usage

FDA and USDA

antimicrobial agents: static

they inhibit growth without killing cells

static microbial agents are best at

preserving lag phase of microbe population

Antimicrobial cidal agents are

killing