MICROBIOLOGY Chapter 25 Microbial Diseases of the Digestive

MICROBIOLOGY Chapter 25 Microbial Diseases of the Digestive System Dr. Abdelraouf A. Elmanama Ph. D Microbiology Medical Technology Department, Faculty of Science, Islamic University-Gaza 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 2008 Figure 25. 1

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

Dental Caries 2008 Figure 25. 3 a, b

Tooth Decay 2008 Figure 25. 4

Periodontal Disease 2008 Figure 25. 5

Bacterial Diseases of the Lower Digestive System • 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 2008

Staphylococcal Food Poisoning • Staphylococcus aureus enterotoxin is a superantigen 2008 Figure 25. 6

Shigellosis • Shigella spp. producing Shiga toxin • Shiga toxin causes inflammation and bleeding 2008 Figure 25. 8

Salmonellosis • Salmonella enterica serovars such as S. enterica Typhimurium • Mortality (<1%) due to septic shock caused by endotoxin 2008 Figure 25. 9

Salmonellosis and Typhoid Fever Incidence 2008 Figure 25. 10

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

Cholera • Vibrio cholerae serotypes that produce cholera toxin • Toxin causes host cells to secrete Cl–, HCO–, and water 2008 Figure 25. 12

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

Escherichia coli Gastroenteritis • 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 O 157: H 7 produce Shiga toxin • O = cell wall antigen • H = flagellar antigen 2008

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

Helicobacter Peptic ulcer disease • Treated with antibiotics • H. pylori causes stomach cancer 2008 Figure 11. 11

Helicobacter Peptic ulcer disease 2008 Figure 25. 13

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

Clostridium perfringens Gastroenteritis • Grow in intestinal tract producing exotoxin 2008

Bacillus cereus Gastroenteritis • Ingestion of bacterial exotoxin produces mild symptoms 2008

Mumps • Mumps virus • Enters through respiratory tract • Infects parotid glands • Prevented with MMR vaccine 2008 Figure 25. 14

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

Hepatitis Transmission Causative agent Chronic liver disease Vaccine Hepatitis A Fecal-oral Picornaviridae No Inactivated virus Hepatitis B Parenteral, STD Hepadnaviridae Yes Recombinant Hepatitis C Parenteral Filoviridae Yes No Hepatitis D Pareteral, HBV coinfection Deltaviridae Yes HBV vaccine Hepatitis E Fecal-oral Caliciviridae No No 2008 Table 25. 1

Hepatitis B Virus 2008 Figure 25. 15

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 2008 Figure 25. 17

Mycotoxins • 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 2008

Giardiasis • Giardia lamblia • Transmitted by contaminated water • Diagnosed by microscopic examination of stool for ova and trophozoite • Treated with metronidazole 2008 Figure 25. 18

Cryptosporidiosis • 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 Figure 25. 19

Cyclospora Diarrheal Infection • Cyclospora cayetanensis • Transmitted by oocysts in contaminated water • Diagnosed by microscopic examination for oocysts • Treated with trimethoprim and sulfamethoxazole 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. 18 b 2008

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

Helminthic Diseases of the Digestive System 2008 Figure 25. 21

Tapeworms • 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 Figure 12. 27

Tapeworms 2008 Figure 25. 22

Hydatid Disease • Echinococcus granulosus • Definitive host: Dogs, wolves • Intermediate host: Sheep and other herbivores; Humans • Transmitted by ingesting E. granulosis eggs • Treatment is surgical 2008 Figure 25. 23

Echinococcus granulosus 2008 Figure 12. 28

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

Pinworms 2008 Figure 12. 29

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

Hookworms 2008 Figure 25. 24

Hookworms 2008 Figure 12. 30

Ascariasis • Ascaris lumbricoides • Lives in human intestines • Transmitted by ingesting Ascaris eggs • Treated with mebendazole 2008 Figure 25. 25

Trichinosis • 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 Figure 25. 26

Trichinosis Garbage, including undercooked or raw pork 1 Adult Trichinella spiralis develop, invade intestinal wall of pig, and produce larvae that invade muscles. Capsule 2 5 Meanwhile, other animals are infected by eating infected meat that has been dumped. Section showing T. spiralis larvae encysted in pig’s muscle tissue (capsule is 0. 25 to 0. 5 in length). Section of T. spiralis Undercooked pork 3 Human eats undercooked pork containing cysts. 4 In human intestine, cyst walls are removed, and T. spiralis adults develop. Adults produce larvae that encyst in muscles. T. spiralis adult 2008 Figure 25. 26