2 nd lecture, bacteriology

1. 2nd lecture, bacteriology Note that there are a lot of information in the sheet are not included here, also there are a lot of information mentioned in the slides are not in the sheet, what is colored in red is from the sheet, I did my best to clarify these slides, enjoy.

2. Diarrheagenic E. coli-1 • There are 6 groups of E. coli strains which have virulence factors causing human diarrhea..Widely distributed in water, and the intestine of animals & Birds and human • .there are.4 most important types 1-Enterotoxigenic E. coli (ETEC). Common in domestic animals, Poultry, Humans .it. ProducesHeat stable (ST) or Heat -labile enterotoxins ( LT).. (plasmid borne) or both it is attached to enterocytes of the small intestine’s epithelium by fimbrial adhesins attachment

3. Contin.. • LT subunit B.. Similar to Cholera toxin, attached to GM1 Ganglioside, releases subunit A which activates adenylyl cyclase & increases cellular cAMP release . • Heat-stable toxin (ST) activates cGMP.. Both cause prolonged hyper secretion of water & sodium + chloride ions which Inhibits reabsorption of sodium.. Mild/severe watery diarrhea, vomiting, abdominal pain.. No fever.

4. E. coliMucosal Attachment .. AdhesionsbyFimbriae CFA I & CFA II

5. Diarrheagenic E. coli-2 • ETEC strainsare frquent & important cause of diarrhea in infants/very young children & common cause of Traveler’s diarrhea in developed countries. • Contaminated water, Dairy products, fresh vegetable food. • Self- limited with oral rehydration, Antibiotics are rarely needed,developintestinal immunity. • 2-Entero-haemorrhagicE. coli (EHEC) Which are associated with the release of toxins known as Shiga-like toxin / Vero-toxigen.. There are many serotypes associated with this organism, but the most important one is O157: H7. in relation to somatic Ag and O Ag. ,

6. common in intestines of animals/ cows.. and it transmitted to human by close contact or contamination of meats especially raw meats like Hamburger , also contamination of milk & ground beef meat.. causes outbreaks of gastroenteritis & later Haemolytic Uraemic Syndrome (HUS).

7. Diarrheagenic E. coli-3 • Complications:Severe inflammation & ulceration colon, Bloody-purulent diarrhea Haemorrhagic colitis.. If toxin reached blood & reach Kidneys results HUS (HUS).. More severe in children/old patients.. Release Blood+ Protein in urine.. Kidney failure highly fatal. • Prevention is better than treatment with antimicrobials. • 3-Entero-pathogenic E.coli(EPEC).. K, Related to lipopolysaccharidesLPS Antigens adherence to GI epithelium & distortion.. numerous serotypes.. often produce diarrhea in neonates up to age 6 months. Outbreaks watery diarrhea & vomiting in infant nurseries aged less 6 months.. Normally produce mild diarrhea but may associated with chronic diarrhea and death of the child • .

8. Contin.. • 4-Entero-invasive E.coli (EIEC).. Similar to Shigella causes bloody diarrhea due to ulceration in large intestine ,Vomiting, Abdominal pain, Fever.. by invasion of damaging intestinal epithelial cells.. necrosis.. Affect all ages..more common and severe in children

9. Lab Diagnosis of all types of DiarrhagenicE.coli • Detection of Diarrheagenic E. coli strains in the laboratory is difficult.. complicated by the fact that non-virulent E. coli strains are commonly present in the feces. • Stool culture on MaConkey agar and other type of agar can't easily distinguish between pathogenic and not pathogenic ones. Identification by PCR more accurate than biochemical and serotyping. • 4-Entero-invasive E.coli (EIEC).. Similar to Shigella causes bloody diarrhea due to ulceration in large intestine ,Vomiting, Abdominal pain, Fever.. by invasion of damaging intestinal epithelial cells.. necrosis.. Affect all ages..more common and severe in children

10. Contin.. • 4-Entero-invasive E.coli (EIEC).. Similar to Shigella causes bloody diarrhea due to ulceration in large intestine ,Vomiting, Abdominal pain, Fever.. by invasion of damaging intestinal epithelial cells.. necrosis.. Affect all ages..more common and severe in children

11. Campylobacter • Campylobacter spp. are Microaerophlic, Gram-negative,Spiral shape.. Bipolar flagella.. Motile.. microaerophilic bacteria, not easily identified in normal culture media, it needs special antibiotic type media campylobacter media. • Commonly present in the GIT of domestic animals.. poultry & pets.. Contaminate easily Meat, Dairy products, fresh Food & Direct contact with animals.. Common cause of diarrhea in Western countries..Less in Arab countries. Depending on species of campylobacter, there’re many types of the diarrhea

12. Contin.. • Campylobacter jejuni:Release Endotoxin & various enterotoxin/cytotoxins.. Acute enteritis,Watery Diarrhea and rarely bloody diarrhea(in the slides is says bloody diarea but the sheet says it rarely cause it) , few days, Infants, children > adults, Elderly. Rare septicemia, Reactive arthritis followed chronic diarrhea. • Infection is mostly self-limited without treatment. Prolong carriage associated with immunodeficiency.

13. Contin.. • Campylobacter fetus.. Less common human diarrhea( in the sheet it says more common).. Commonly causes sepsis & abortion in animals. Culture is more significant then serological test in diagnosis clinical chronic cases. • Treatment: Macrolides/Azithromycin, Ciprofloxacin, Ampicillin (Normally, under health condition, no need to give antibiotic drugs, only control dehydration, if necessary replacing by oral tube without any complication.)

14. Campylobacter- Vibrio cholera

15. Helicobacter pylori • This is the only organism which has many association with the mucosa of our gastrointestinal specially stomach mainly gastric antrum. • Microaerophlic growth.. Gram-ve spiral shape, motile, polar 4-6 flagella .. produces potent urease,neutralize stomach acidity, allow colonizing mucus overlaying gastric mucosa mainly gastric antrum. • H. pylori colonize stomach of 30%-90% of world’s population according their age.. Mostly without signs or symptoms and may not cause any disease.

16. Contin.. • Pathogenicity: Protease, outer membrane antigens & Cytotoxinscausing chronic inflammation of the inner lining of the stomach mucosa.. Gastritis, Peptic /dudenal ulcers. , first mild unrecognized later increase in about .about 2 % infected persons. • H. pylori discovered 1983 as cause of chronic gastritis.. Complications Gastric lymphoma, Stomach cancerin infected persons over a long period.

17. Helicobacter infection

18. Diagnosis & Treatment • Infection is most likely acquired by ingesting food, water, personal/family contact. Re-infection is common. Optimal growth..selective culture medium with 90% Co2 , 42 C, 3-5 days. More acidity cause more ulceration. • Diagnoses: A) clinically by Urea breath test , using urea capsule labeled with active carbon detects urease activity in stomach by splitting urea into Co2 & Ammonia. B) A rapid urease test for identification H. pylori in gastric biopsy taken by endoscope or culture Giemsa /silver stain by histological examination. Serological antibodies test is less significant.

19. Contin.. Treatment : there are 2-3 antibiotics should given together , like metronidazole and clarithromycin and anti-acids , this combination should be continued at least 4 weeks , eradicated is not 100%. It’s only for short period. Patient will recurrent this infection. • Infection is not easily controlled without controlling the stress condition. or Metronidazole + Amoxicillin + H2 Blockers..

20. Vibrios-1 • Vibrio group is Gram-negative straight or curved rods, oxidase-positive, motile, single polar flagellum.. Most types are found Commonly in sea water-human cycle. There are 20 species, 2 main types are • Classical V. cholerae(- in relation to presence of somatic Ag 01), 0139 El-tor type.. Infect only human.. Cause Epidemic/Pandemic responsible for at least in each year 1,000,000 cases of cholera disease.Outbreaks.. Spread from India subcontinent.

21. Contin.. • Noninvasive.. affecting small intestine through Heat-labile Cholera Toxin (A and B subunits) B-unit binds to Gangliosies release A-unit.. , same mechanism as enterotoxins heat labile toxin of E.coli; Increasing cAMP causing outpouring large amount water, Na+, K+ Cl- , HCO- ..

22. Contin.. • Incubation period . 8-24h..Severe watery diarrhea (1-3 Liters) ,vomiting & cramps, rapid dehydration(which can be within few hours and might end body fluids in less than result in complication, cardiac arrest - kidney failure - death.), shock, blood acidosis, renal failure.. death within 24 h if patient not received replacement of fluid loss . • Partial intestinal immunity.. antitoxin antibodies last for 1-year, Oral vaccine is effective for short period.

23. Vibrios-2 • Non-01 V. cholerae.. found in water along with 0-1 V.cholerae Less virulent.. watery diarrhea similar to classical cholera due to release cytotoxins not so severe . • It’s more cytotoxic  affect mucosa of large intestines. • V. parahaemolyticus.. Halophilic Vibrio.. Cytotoxins Raw fish.Gastroenteritis.. Maycause Sepsis or Wound infection.. Contaminated row fish * Lab Diagnosis: Stool culture.. Special culture TCBS ((4 components: Thiosulfate-citrate-bile salts-sucrose medium ) ),

24. Contin.. Biochemical & serotyping confirmation with specific cholera antisera to differentiate different subtypes. * Treatment: Oral rehydration is the main treatment.. Replacement of fluid loss..doxycycline, cotrimoxazole (children), ciprofloxacin reduce the Vibrios excretion *Prevention:you should have Safe water & Food.. Early detection of positive infected cases prevent outbreak of cholera in community.. No Healthy carriers.

25. FoodborneToxigenic Bacteria-1 • Food poisoning organisms , are not important only in presence of bacteria in intestinal tract , it’s more important in release of toxins in already presented food , which means if there is contamination of food particles with these types of bacteria , you should expect that these organisms will release potent toxins  responsible for food poisoning or what we called food intoxication .

26. Contin.. • Staphylococcus aureusstrains associated with specific bacteriophage types can produce several Heat-stable protein exotoxins in food ( 20 minutes 100C), Fast absorbed from small Intestine to Blood stream & affects CNS. Staphylococcal food poisoning is commonly associated with salty foods, cream cakes, grounded meat.. Fresh dairy products.. White chesses.

27. Contin.. • Main Symptoms: 30 minutes-6 hours following the consumption of the contaminated food.. vomiting, nausea, stomach cramps.. rarely watery diarrhea.. No fever & recovery within 1-2 days.. Self-limited. • Diagnoses: detection of Staph. toxins in eaten food.

28. FoodborneToxigenic Bacteria-2 Bacillus cereus.. G+ve Aerobic Spore-Forming Bacilli,Common in Nature.. Spores survive boiling and cooling/refrigeration Food.. Produces 2 types of toxins, exotoxins/ enterotoxinsproduced during bacilli sporulation either in Food or Intestine.. Associated with two main gastrointestinal symptoms. • 1-Intoxication .. Heat-Acid stable Emetic Enterotoxins..Typically developed within 1-24 hours of eating contaminated fried rice, meat.. Vomiting nausea, stomach cramps last for few hours without diarrhea & fever. 2- Diarrheal Toxins/HL..watery mild diarrhea.. No Fever or Vomiting..self-limiting within 1-3 days. • Both Types of toxins may produce from the same B. cereus strain.. Mostly outbreaks in family, schools & commonly associated with Chinese food.. Fried rice

29. Clostridium difficile • Anaerobic, spore-forming Gram+ve, Part of normal intestinal flora of neonates & infants.. Adults (5-20%).. Rapidly increased colonization in hospitalized patients & become active danger after antibiotic treatment for more than 1 week.. with all wide-spectrum peniciilins, clindamycincephalosporins.. Often causes nosocomial infection among elderly, surgery & compromised patients. • Antibiotic-associated enterocolitis developed by release 2 toxins types (enterotoxin A, cytotoxin B) acting directly on intestinal epithelial cells causing necrosis.. Bloody diarrhea.. Increased rapidly within days to severe Pseudomembranous colitis.. Anothernew strain producing more potent binary toxin detected few years ago. Treatment: stop use potentialcausative antibiotics, use metronidazole / vancomycin will prevent disease complication.

30. Done by Mohanned Momani, dedicated to mamoon and ameen kajjon