Chapter 25 Digestive system infections Medgar Evers College, CUNY Bio 261 Dr. Santos

Basic anatomy of the human digestive system IIeum of small intestine Duodenum of small intestine Appendix Cecum Ascending portion of large intestine Anus Small intestine Large intestine Rectum Liver Gall- bladder Tongue Oral cavity Pharynx Esophagus Stomach Pyloric sphincter Cardiac orifice Mouth Salivary glands Pancreas Large intestines Small intestines Parotid gland Sublingual gland Submandibular gland A schematic diagram of the human digestive system

Normal microbiota of the digestive system Different species colonize the mouth depending on their ability to attach to specific receptors. Dental plaque consists of many bacteria of different species attached to the teeth or each other. Anaerobic bacteria are also present.

Bacterial infections of upper digestive system Disease Cause symptoms pathogenesis treatment Dental caries or tooth decay *incubation period is 1 to 24 months Streptococcus mutans Severe pain, discoloration of tooth or breakage Glucan is produced from sucrose. This is needed for dental caries production Restrict sugar, fluoride in toothpastesee dentist regularly

Bacterial infections of upper digestive system Disease Cause symptoms pathogenesis treatment Periodontal disease Dental plaque Bleeding, sensitive gums, bad breath, loosening of the tooth, Bacteria produces inflammatory response, plaque forms, widens and anaerobic bacteria grow, toxins and enzymes degrade tissue Avoid buildup of plaque and surgery if needed

Bacterial infections of upper digestive system Disease Cause symptoms pathogenesis treatment Trench mouth (acute necrotizing ulcerative gingervitis) A spirochete of genus Treponema Fever, painful bleeding gums, foul mouth odor Tissue destruction, ulceration and tissue invasion by spirochete. Antibiotic treatment

Bacterial infections of upper digestive system Disease Cause symptoms pathogenesis treatment Helicobacter pylori gastritis H. pylori Vomiting, belching, abdominal pain and tenderness and bleeding if ulcer or cancer associated Pathogen survives acidity of stomach, penetrates mucus, inflammatory response, thinning of mucus can occur if ulcer forms Antibiotics and medication to suppress acid formation

H. pylori Gram – Microaerophile Multiple polar flagella for motility Produces urease to neutralize acidity of stomach Buries itself on the mucus layer to survive

Viral infections of upper digestive system Disease Cause symptoms pathogenesis treatment Herpes HSV Type 1 Fever, sore throat, pain in lip followed by blisters Virus replicates in the epithelium, an immune response follows, but virus hides in sensory nerves Anti viral medication such as acyclovir, penciclovir

Viral infections of upper digestive system Disease Cause symptoms pathogenesis treatment Mumps *incubation period is 15 to 21 days Mump virus **Only one serotype of the mumps virus is known. Fever, headache, loss of appetite, painful swollen parotid glands, painful enlarged testicles, pelvic pain in women Virus replicates in the upper respiratory tract and then travels to parotid glands, inflammatory response occurs An effective attenuated vaccine since 1967 has been in place since then.

Bacterial infections of lower digestive system Disease Cause symptoms pathogenesis treatment Cholera Vibrio cholerea Massive diarrhea, vomiting, muscle cramps Exotoxins that cause excessive excretion of electrolytes by the intestinal epithelium; leads to dehydration and shock Purification of water supply, rehydration with electrolyte and glucose

Bacterial infections of lower digestive system Disease Cause symptoms pathogenesis treatment Shigellosis Species of shigella Fever, dysentery, vomiting headache, stiff neck, painful joints Pathogen invades and multiplies within the intestinal epithelium Antibiotics such as ampicillin, sanitary measures,

Bacterial infections of upper digestive system Disease Cause symptoms pathogenesis treatment Gastroenteritis caused by E.coli E. coli Vomiting and diarrhea, sometimes dysentery (crampy abdominal pain and bloody diarrhea) Attachment, toxins, invasion of intestinal epithelium, loss of microvilli Bismuth compound treatment, sanitary conditions, replacement of fluids loss

Bacterial infections of lower digestive system Disease Cause symptoms pathogenesis treatment Salmonellosis Salmonella enterica Diarrhea, vomiting, Invasion and penetration of tissue, inflammatory response No treatment unless tissue invasion then antimicrobial agent

Bacterial infections of lower digestive system Disease Cause symptoms pathogenesis treatment Campylobacteriosis Campylobacter jejuni Diarrhea, fever, abdominal cramps, nausea, vomiting, bloody stool Low infecting dose, pathogen multiplies within and beneath the epithelial cells, inflammatory response Sanitary measures, and no antimicrobial treatment

Viral infections of lower digestive system Disease Cause symptoms pathogenesis treatment Hepatitis A (acute and rarely leads to long term liver or permanent damage) Nonenveloped ss RNA picorna virus Fatigue, fever, loss of appetite, nausea, right sided abdominal pain, dark colored urine Viral replication and damage restricted to liver. How it gets there is still being investigated Inactivated vaccine

Viral infections of lower digestive system Disease Cause symptoms pathogenesis treatment Hepatitis B (infected blood or body fluid/oral) Enveloped ds DNA hepadnavirus More severe than A, progressive liver damage, can lead to cirrhosis and cancer HBV is carried to liver by bloodstream, attaches and invades liver cells Combined Hepatitis A and B vaccine

Viral infections of lower digestive system Disease Cause symptoms pathogenesis treatment Hepatitis C (most commonly transmitted by sharing needles) *baby boomers! Enveloped ss RNA flavivirus Few or no symptoms, progressive liver damage or cancer in 10 to 20% of cases Liver cells are infected and replication occurs, inflammatory response occurs No vaccine but one should avoid alcohol use and anti viral medication if needed

2 other viral infections of the lower 1- rotaviral gastroenteritis, most common cause of viral gastroenteritis in children and infants 2- noroviral gastroenteritis, most common cause of viral gastroenteritis in the USA

Protozoan infections of lower digestive system Disease Cause symptoms pathogenesis treatment Giardiasis Giardia lamblia, a pear shaped protozoan Flatulence, nausea, vomiting, diarrhea, abdominal cramps, weight loss Host immune response to attachment of pathogen to epithelial lining Antimicrobial medications such as atabrine or flagyl

Protozoan infections of lower digestive system Disease Cause symptoms pathogenesis treatment Cryptosporidiosis Cryptosporidium parvum Fever, loss of appetite, nausea, crampy abdominal pain, watery diarrhea lasting 10 to 14 days Invasion of epithelial cells, inflammatory response No effective treatment exists but sanitary conditions should be kept, pasteurization of beverages

Protozoan infections of lower digestive system Disease Cause symptoms pathogenesis treatment Cyclosporiasis Cyclospora cayetanensis Fatigue, loss of appetite, vomiting, watery diarrhea, weight loss Very little is known Bactrim, Septra antimicrobial agents, boil water before drinking

Protozoan infections of lower digestive system Disease Cause symptoms pathogenesis treatment Amebiasis Entamoeba histolytica Diarrhea, abdominal pain, blood in feces Ingested cysts liberate the pathogen, reach large intestine, feed on mucus and cells lining the intestine, and sometimes they penetrate the lining by using enzymes Metronidazole or paromomycin