MICROBIAL DISEASES OF THE DIGESTIVE

SYSTEM

MOUTH• Over 300 types of bacteria• Dental caries• Periodontal disease

–Gingivitis

–Periodontitis

DENTAL CARIES• Dental plaque

–Accumulation of microorganisms and their products (dental plaque)

–Streptococcus mutans

–Actinomyces spp.

DENTAL CARIES (cont.)

• Attachment• Colonization• Sugar (glucose+fructose)• Glucose > dextran• Fructose > lactic acid

Enamel

DENTAL CARIES (cont.)• Lactic acid softens enamel• Initial, S. mutans• Advance, Lactobacillus spp.• Pulp infection

DENTAL CARIES (cont.)• Treatment

– Root canal therapy– Penicillin

• Prevention– Fluoride– Reduced sucrose in diet– Brushing and flossing– Professional cleaning

PERIODONTAL DISEASE

• Inflammation of teeth-supporting tissue• Gingivitis

– Gums inflammation (bleeding)

PERIODONTAL DISEASE (cont.)

• Streptococci, actinomyces and gram-negative bacteria

• Prevented by brushing & flossing

PERIODONTITIS• Chronic gingivitis• 10% of teeth loss• Affects bone• Surgery and cleaning

LOWER DIGESTIVE SYSTEM

• Infections

–Salmonellosis• Intoxications

–Staphylococcus aureus

Practice that contributed to food-borne disease (1988-1992)

1. Improper holding temperature2. Poor personal hygiene of food

handlers3. Food obtained from an unsafe

source was the least commonly reported factor

Syndrome

• A group of symptoms that together are characteristic of a specific disease

Gastrointestinal Syndrome• Gastroenteritis associated with

nausea, vomiting and diarrhea

Dysentery syndrome

• Any infectious disease of the large intestine marked by ulceration, hemorrhagic diarrhea with mucus and often blood

GASTROENTERITIS• Inflammation of the stomach and

intestinal mucosa

GASTROENTERITIS (cont.)

• Abdominal cramps• Nausea• Vomiting• Dehydration

GASTROENTERITIS (cont.)

• E. coli• Shigella spp.• Salmonella spp.• Campylobacter spp.• Staphylococcus aureus• Rotavirus• Norwalk virus (Noro virus)

Routes of exposure to enteric pathogens

• Fecal contamination (human/animal)

–Food

–Water

–Fomites (doorknobs, telephones)

–Direct contact

Petting zoos

Non-traditional pets

Pest animals

Population at risk

Occupational risk

STAPHYLOCOCCAL FOOD POISONING

• S. aureus survives 30 min at 60o C (140o F)

• High salt concentration• Skin and nasal mucosa• Facultative anaerobes

-Coagulase positive

STAPHYLOCOCCAL FOOD POISONING

(cont.)• Temperature abuse

–Food let to cool slowly

–Organisms grow producing toxin

STAPHYLOCOCCAL FOOD POISONING

(cont.)• High risk foods

–Custards

–Cream pies

–Ham

STAPHYLOCOCCAL FOOD POISONING (cont.)

• Toxin affects brain’s vomiting reflex

• Abdominal cramps• Diarrhea

SALMONELLOSIS

Salmonella spp.

• Gram negative rods• Facultative anaerobe• 2000 serovars

SALMONELLOSIS (cont.)

• S. dublin• S. enteritidis• S. typhimurium• S. cholerasuis

SALMONELLOSIS (cont.)

• Domestic animals

–Poultry

–Swine

–Cattle

–Dogs and cats

SALMONELLOSIS (cont.)

• Wild animals

–Rodents

–reptiles

–Terrapins (turtles)

SALMONELLOSIS (cont.)

• Incubation of 12 - 36 h• Intestinal mucosa• Lymphatic and cardiovascular

systems

SALMONELLOSIS (cont.)

• Fever• Nausea• Abdominal pain• Cramps• Diarrhea

SALMONELLOSIS (cont.)

• Mortality among infants and the elderly

• Many shed Salmonella for 6 months

• Many animals are chronic carriers

SALMONELLOSIS (cont.)

• Treatment

–Rehydration

–Antibiotics prolong carrier state and increase resistance

TYPHOID FEVER

• Salmonella typhi

–Rare in animals!• Incubation

–2 weeks

TYPHOID FEVER (cont.)

• High fever (104o F)• Continual headache• Constipation more common

than diarrhea• 10% fatality rate

TYPHOID FEVER (cont.)• Many recovered patients become

carriers (Typhoid Mary)• Obligatory case report in most

states and countries• Lifelong immunity

TYPHOID FEVER (cont.)• Treatment

–Cephalosporins

–Chloramphenicol

–Amoxillin

Shigellosis

SHIGELLOSIS (Bacillary dysentery)

• Shigella spp.• Gram negative facultative anaerobic

rod• Only infects humans• Low infectious dose

–Resistant to low stomach pH

SHIGELLOSIS (cont.)• S. sonnei

– Most common in the USA– Least severe

• S. dysenteriae –Uncommon in the USA –Most severe

SHIGELLOSIS (cont.)• Shiga toxin

–Inhibits protein synthesis

–Diarrhea with blood and mucus (dysentery)

SHIGELLOSIS (cont.)• 20,000- 25,000 cases/year• 5 to 15 deaths• Treatment

–Rehydration

–Fluoroquinolones (severe cases)

Cholera

CHOLERA• Vibrio cholerae• Aquatic organism• Gram-negative rod • Non-invasive

–toxin producing

Cholera epidemicSouth America1991-1994• 1 million cases• 9,600 deaths

CHOLERA (cont.)• Enterotoxin• Rice-water stools• 20 liters of liquid lost/day• Occasional outbreaks in Gulf coast

(seafood)

CHOLERA (cont.)• 50% mortality if untreated• 1% mortality if treated

–Rehydration

–Tetracycline

Vibrio gastroenteritis• Vibrio parahaemolyticus• Salt water estuaries• Resembles cholera• Often foodborne (seafood)

E. coli

Escherichia coli gastroenteritis

• Enterotoxigenic E. coli• Enteroinvasive E. coli• Enterohemorrhagic E. coli

Enterotoxigenic E. coli

• Specialized fimbriae

–Attachment• Not invasive• Toxins• Severe diarrhea

Enteroinvasive E. coli• Specialized fimbriae

–Attachment• Toxins (cholera-like)• Traveler’s diarrhea (?) • Penetrate intestinal lining

–Shigellosis-like dysentery

Enterohemorrhagic E. coli• O157:H7 strain• Foodborne (hamburgers, milk,

apple cider)• Verotoxins (colon bleeding)

Enterohemorrhagic E. coli (cont.)

• Cattle carrier• Hemolytic uremic syndrome

–Blood in urine

–Kidney failure

Campylobacter jejuni gastroenteritis

• Gram-negative microaerophilic spirally curved rods

• Common in (healthy) domestic animals

–May be shed in milk• Small infectious dose• Dysentery

Yersinia spp. gastroenteritis

• Common in domestic animals• Grows at refrigeration temperature• Acute pain

Clostridium perfringens gastroenteritis

• Gram-positive, spore-forming anaerobic rod

• Contaminated-cooked meat• Temperature abuse• Mild diarrhea

Bacillus cereus gastroenteritis

• Gram-positive, spore-forming anaerobic rod

• Common in soil and vegetation• Gastroenteritis is similar to Cl.

perfringens

VIRAL GASTROENTERITIS

ROTAVIRUS• Most common viral gastroenteritis• 1,000,000 cases/year (USA)• 100 deaths/hour• (developing countries)

NORWALK VIRUS• Common among adults• More resistant to chlorine than

other viruses• No animal models or cell culture

available