The Human Digestive System Figure 25.1

Normal Microbiota Millions of bacteria per ml of saliva Large numbers in large intestine 100 billion bacteria per gram of feces

Defenses Stomach: Acidic Small intestine: Paneth cells

A Healthy Human Tooth Figure 25.2

Dental Caries (Tooth Decay) Figure 25.3a

Dental Caries (Tooth Decay) Figure 25.3b

The Stages of Tooth Decay Figure 25.4

Bacterial Diseases of the Mouth Pathogen Dental caries Streptococcus mutans Periodontal disease Porphyromonas spp. Acute necrotizing gingivitis Prevotella intermedia

Diseases of Lower Digestive System Infection: Growth of a pathogen Incubation is from 12 hours to 2 weeks Fever Intoxication: Ingestion of toxin Symptoms appear 1 to 48 hours after ingestion Gastroenteritis: Diarrhea, dysentery Treatment: Oral rehydration therapy

Staphylococcal Food Poisoning Pathogen Staphylococcus aureus Symptoms Nausea, vomiting, and diarrhea Intoxication/Infection Intoxication Enterotoxin (superantigen) Diagnosis Phage typing Treatment None

Shigellosis (Bacillary Dysentery) Pathogen Shigella spp. Symptoms Tissue damage and dysentery Intoxication/Infection Infection Endotoxin and Shiga exotoxin Diagnosis Isolation of bacteria Treatment Quinolones

Invasion of Intestinal Wall by Shigella Figure 25.7

Shigellosis Figure 25.8

Salmonellosis and Typhoid Fever Figure 25.10

Typhoid Fever Caused by Salmonella typhi Bacteria spread throughout body in phagocytes 1–3% of recovered patients become chronic carriers

Disease Salmonellosis Typhoid Fever Pathogen Salmonella enterica S. typhi Symptoms Nausea and diarrhea High fever, significant mortality Intoxication/ Infection Infection Endotoxin Diagnosis Isolation of bacteria; serotyping Treatment Oral rehydration Quinolones; cephalosporins

Vibrios Cholera Noncholera vibrios Vibrio cholerae serotypes that produce cholera toxin Toxin causes host cells to secrete Cl–, HCO–, and water Noncholera vibrios Usually from contaminated crustaceans or mollusks V. cholerae serotypes other than O:1, O:139, eltor V. parahaemolyticus V. vulnificus

Vibrio cholerae Figure 25.11

Vibrio cholerae O:1 and O:139 V. vulnificus Disease Cholera Noncholera vibrios Pathogen Vibrio cholerae O:1 and O:139 V. parahaemolyticus V. vulnificus Symptoms Diarrhea with large water loss Cholera-like diarrhea, but generally milder Rapidly spreading tissue destruction Intoxication/Infection Cholera toxin (exotoxin) Infection, enterotoxin Infection, siderophores Diagnosis Isolation of bacteria Treatment Rehydration; doxycycline Rehydration; antibiotics Antibiotics

Escherichia coli Gastroenteritis Pathogenic E. coli Attach to intestinal cells with fimbriae Produce toxins May aggregate

Escherichia coli Gastroenteritis Disease Traveler’s Diarrhea STEC Pathogen Enterotoxigenic, enteroinvasive, enteraggregative E. coli Shiga-toxin-producing E. coli Symptoms Watery diarrhea Shigella-like dysentery; hemorrhagic colitis and hemolytic uremic syndrome

Escherichia coli Gastroenteritis Disease Traveler’s Diarrhea STEC Intoxication/Infection Infection Endotoxin Infection Shiga exotoxin Diagnosis Isolation of bacteria Treatment Oral rehydration Quinolones; cephalosporins

Helicobacter Peptic Ulcer Disease Figure 25.13

Helicobacter Peptic Ulcer Disease Pathogen Helicobacter pylori Symptoms Peptic ulcers Intoxication/Infection Infection Diagnosis Urea breath, bacterial culture Treatment Antimicrobial drugs

Clostridium and Bacillus Gastroenteritis Pathogen C. perfringens C. difficile B. cereus Symptoms Diarrhea Diarrhea to colitis Nausea and vomiting; diarrhea Intoxication/Infection Infection Exotoxin Intoxication Diagnosis Isolation of bacteria Cytotoxin assay

Clostridium and Bacillus Gastroenteritis Pathogen C. perfringens C. difficile B. cereus Transmitted Metronidazole; discontinue other antibiotic therapy Source of Infection Meats Elimination of normal microbiota Rice dishes

Viral Diseases of the Digestive System Mumps Viral Gastroenteritis Pathogen Mumps virus Rotavirus Norovirus Symptoms Swollen parotid glands Vomiting, diarrhea, 1 wk Vomiting, diarrhea, 2–3 days Incubation 16–18 days 1–3 days 14–48 hr Diagnosis EIA PCR Treatment Preventive vaccine Oral rehydration

A Case of Mumps Figure 25.14

Hepatitis An inflammation of the liver May result from drug or chemical toxicity, EB virus, CMV, or the hepatitis viruses

Hepatitis Viruses Disease Transmission Pathogen Chronic Liver Disease? Vaccine? Hepatitis A Fecal-oral Picornaviridae No Inactivated virus Hepatitis B Parenteral, STI Hepadnaviridae Yes Recombinant Hepatitis C Parenteral Filoviridae None Hepatitis D Pareteral, HBV coinfection Deltaviridae HBV vaccine Hepatitis E Caliciviridae HAV vaccine

Hepatitis B Virus (HBV) Figure 25.15