Medical Technology Department, Faculty of Science, Islamic University-Gaza MB M ICRO B IOLOGY Dr. Abdelraouf A. Elmanama Ph. D Microbiology 2008 Chapter 25 Microbial Diseases of the Digestive System

2008 Microbial Diseases of the Digestive System Transmitted in food and water Fecal-oral cycle can be broken by: Proper sewage disposal Disinfection of drinking water Proper food preparation and storage

2008 The Digestive System Figure 25.1

2008 >300 species in mouth Large numbers in large intestine, including: Bacteroides E. coli Enterobacter Klebsiella Lactobacillus Proteus Normal Microbiota

2008 Dental Caries Figure 25.3a, b

2008 Tooth Decay Figure 25.4

2008 Periodontal Disease Figure 25.5

2008 Symptoms usually include diarrhea, gastroenteritis, dysentery Treated with fluid and electrolyte replacement Infection caused by growth of pathogen Incubation from 12 hr to 2 wk Intoxication caused by ingestion of toxin Symptoms appear 1-48 hr after ingestion Bacterial Diseases of the Lower Digestive System

2008 Staphylococcal Food Poisoning Figure 25.6 Staphylococcus aureus enterotoxin is a superantigen

2008 Shigellosis Figure 25.8 Shigella spp. producing Shiga toxin Shiga toxin causes inflammation and bleeding

2008 Salmonellosis Figure 25.9 Salmonella enterica serovars such as S. enterica Typhimurium Mortality (<1%) due to septic shock caused by endotoxin

2008 Salmonellosis and Typhoid Fever Incidence Figure 25.10

2008 Salmonella enterica Typhi Bacteria spread throughout body in phagocytes 1-3% recovered patients become carriers, harboring Salmonella in their gallbladder Typhoid Fever

2008 Cholera Figure Vibrio cholerae serotypes that produce cholera toxin Toxin causes host cells to secrete Cl –, HCO –, and water

2008 Usually from contaminated crustaceans or mollusks V. cholerae serotypes other than O:1, O:139, and eltor V. parahaemolyticus V. vulnificus Noncholera Vibrios

2008 Occurs as traveler's diarrhea and epidemic diarrhea in nurseries 50% of feedlot cattle may have enterohemorrhagic strains in their intestines Enterohemorrhagic strains such as E. coli O157:H7 produce Shiga toxin O = cell wall antigen H = flagellar antigen Escherichia coli Gastroenteritis

2008 Campylobacter jejuni Usually transmitted in cow's milk Campylobacter Gastroenteritis

2008 Helicobacter Peptic ulcer disease Treated with antibiotics H. pylori causes stomach cancer Figure 11.11

2008 Helicobacter Peptic ulcer disease Figure 25.13

2008 Y. enterocolitica and Y. pseudotuberculosis Can reproduce at 4°C Usually transmitted in meat and milk Yersinia Gastroenteritis

2008 Grow in intestinal tract producing exotoxin Clostridium perfringens Gastroenteritis

2008 Ingestion of bacterial exotoxin produces mild symptoms Bacillus cereus Gastroenteritis

2008 Mumps Figure Mumps virus Enters through respiratory tract Infects parotid glands Prevented with MMR vaccine

2008 Inflammation of the liver Hepatitis may result from drug or chemical toxicity, EB virus, CMV, or the Hepatitis viruses Hepatitis

2008 Hepatitis Table 25.1 TransmissionCausative agentChronic liver disease Vaccine Hepatitis AFecal-oralPicornaviridaeNoInactivated virus Hepatitis BParenteral, STDHepadnaviridaeYesRecombinant Hepatitis CParenteralFiloviridaeYesNo Hepatitis DPareteral, HBV coinfection DeltaviridaeYesHBV vaccine Hepatitis EFecal-oralCaliciviridaeNo

2008 Hepatitis B Virus Figure 25.15

2008 Viral Gastroenteritis Rotavirus 3 million cases annually 1-2 day incubation, 1 week illness Norovirus 50% of U.S. adults have antibodies 1-2 day incubation. 1-3 day illness Treated with rehydration Figure 25.17

2008 Mycotoxins are produced by some fungi: Claviceps purpurea Grows on grains Produces ergot Toxin restricts blood flow to limbs; causes hallucination Aspergillus flavus Grows on grains Produces aflatoxin Toxin causes liver damage; liver cancer Mycotoxins

2008 Giardiasis Figure Giardia lamblia Transmitted by contaminated water Diagnosed by microscopic examination of stool for ova and trophozoite Treated with metronidazole

2008 Cryptosporidiosis Figure Cryptosporidium parvum Transmitted by oocysts in contaminated water Diagnosed by acid-fast staining of stool or presence of antibodies by FA or ELISA Treated with oral rehydration

2008 Cyclospora cayetanensis Transmitted by oocysts in contaminated water Diagnosed by microscopic examination for oocysts Treated with trimethoprim and sulfamethoxazole Cyclospora Diarrheal Infection

2008 Amoebic Dysentery Entamoeba histolytica Amoeba feeds on RBCs and GI tract tissues Diagnosis by observing trophozoites in feces Treated with metronidazole

2008 Amoebic Dysentery Figure 25.20

2008 Amoebic Dysentery Figure 12.18b

Medical Technology Department, Faculty of Science, Islamic University-Gaza MB M ICRO B IOLOGY Dr. Abdelraouf A. Elmanama Ph. D Microbiology 2008 Chapter 25 Microbial Diseases of the Digestive System

2008 Helminthic Diseases of the Digestive System Figure 25.21

2008 Tapeworms Figure Taenia spp. Transmitted as cysticerci in undercooked meat Cysticerci may develop in humans Diagnosed by observing proglottids and eggs in feces Treatment with praziquantel Neurocysticercosis may require surgery

2008 Tapeworms Figure 25.22

2008 Hydatid Disease Figure Echinococcus granulosus Definitive host: Dogs, wolves Intermediate host: Sheep and other herbivores; Humans Transmitted by ingesting E. granulosis eggs Treatment is surgical

2008 Echinococcus granulosus Figure 12.28

2008 Pinworms Enterobius vermicularis Definitive host: Humans Transmitted by ingesting Enterobius eggs Treatment with pyrantel pamoate or mebendazole

2008 Pinworms Figure 12.29

2008 Hookworms Larvae in soil hatched from eggs shed in feces Larvae bore through skin; migrate to intestine Treated with mebendazole

2008 Hookworms Figure 25.24

2008 Hookworms Figure 12.30

2008 Ascariasis Figure Ascaris lumbricoides Lives in human intestines Transmitted by ingesting Ascaris eggs Treated with mebendazole

2008 Trichinosis Figure Trichinella spiralis Larvae encyst in muscles of humans and other mammals Transmitted by ingesting larvae in undercooked meat Treated with mebendazole to kill adults worms

2008 Trichinosis Figure Adult Trichinella spiralis develop, invade intestinal wall of pig, and produce larvae that invade muscles. Section showing T. spiralis larvae encysted in pig’s muscle tissue (capsule is 0.25 to 0.5 in length). Human eats undercooked pork containing cysts In human intestine, cyst walls are removed, and T. spiralis adults develop. Adults produce larvae that encyst in muscles. 4 Meanwhile, other animals are infected by eating infected meat that has been dumped. 5 Capsule Section of T. spiralis Undercooked pork Garbage, including undercooked or raw pork T. spiralis adult