Infectious diarrhea caused by bacteria

Most common bacterial pathogens causing diarrhea.

1. Infectious diarrhea caused by bacteria SZU agata sirek and Ilkin Bakirli 5 th Year 26.04.19

2. Table of contents D iarrhea Microbiology and pathogenesis Salmonella spp Shigella spp Escherichia Coli Campylobacter spp Vibrio spp Yersinia spp Clostridium difficile Diagnosis

3. Infectious (bacterial) diarrhea D iarrhea is defined as having loose or watery stools three or more times a day Bacterial diarrhea is always acute Common routes of transmission (ROT) of the bacteria are food, water or person-to-person ( fecal -oral) Common symptoms may include diarrhea , vomiting, abdominal pain, fever, dehydration and fatique Most often it is self limited and does not require treatment Causative agents are gram negative rods, have endotoxin (LPS) in their cell wall, have 3 antigens (LPS, flagellar and capsular), produce other enterotoxins/ cytotoxins

4. Salmonella spp Species: S. enteritidis , S. typhymurium , S. typhi , S. paratyphi Bacteria: Gram negative rod, acid labile ROT: ingestion of poultry , contaminated foods (eggs, milk, ice-creams), infected pet turtles Salmonellosis: nausea, vomiting and watery diarrhea within 12-36 hours of bacteria ingestion, fever and abdominal pain may accompany. Self limiting within 2-7 days Typhoid (enteric) fever: severe, fever, myalgia, little/ no diarrhea , vomiting, ( bacteremia ) Treatment: Salmonellosis: electrolyte replacement and rest / ciprofloxacin/levofloxacin/ceftriaxone Typhoid fever: beta lactam (ceftriaxone) + fluoroquinolone (ciprofloxacin)

5. Shigella spp Species: S. flexnerii , S. sonnei , S. boydii , S. dysenteriae Bacteria: Gram negative rod, AB toxin ( shiga toxin), acid stable (low infectious dose) ROT: flies, fecal -oral Shigellosis (bacillary dysentery): symptoms appear 48-72 hours after infection, colitis, bloody diarrhea , abdominal cramping, rectal tenesmus, fever, nausea, vomiting and mucosal ulceration Self limited in 5-7 days Complications- reactive arthritis, haemolytic uremic syndrome, sepsis, seizures Treatment Rehydration and electrolyte replacement Severe cases: trimethoprim-sulfamethoxazole/ ciprofloxacin / azithromycin

6. Escherichia coli (1) Bacteria: gram negative rod, normal flora ROT: fecal -oral, contaminated foods and water 5 different strains of E.coli are identified Enterotoxigenic E.coli (ETEC): heat stable toxin and heat labile toxin ( ≈cholera toxin) w atery diarrhea , no abdominal cramping other symptoms are not frequent Important cause of traveller’s diarrhea and diarrhea in children Enteropathogenic E.coli (EPEC): no toxins Watery diarrhea in infants, infection acquired perinatally attachment/effacement lesions in the small intestine, microvilli destruction

7. Escherichia coli (2) Enterohemmorhagic E.coli (EHEC): 2 exotoxins, shiga -like toxin 1 and 2 Unlike other strains, it infects the colon and not the small intestine Copious bloody diarrhea with abdominal cramping, no fever, resolves in 5-10days Transmitted through consuming raw milk and undercooked beef Serotype O157:H7 is associated with haemolytic uremic syndrome, acute renal failure and haemolytic anemia Enteroinvasive E.coli (EIEC): no toxins, but can spread cell to cell by actin polymerisation Dysentery-like syndrome (bloody diarrhea , fever, ≈bacillary dysentery) Enteroaggregative E.coli (EAEC): produces a heat stable toxin, causes watery diarrhea in traveller’s and persistent diarrhea in patients infected with HIV

8. Escherichia coli (3) Other diseases- UTIs, neonatal meningitis, nosocomial sepsis/ pneumonia/ endotoxic shock Treatments Fluid and electrolyte replacement For ETEC, EPEC, EIEC and EAEC- according to sensitivity amoxicillin / cefotaxime / trimethoprim-sulfamethoxazole / ciprofloxacin For EHEC: no treatment, antibiotics may worsen HUS

9. Campylobacter spp Species: C. jejuni , C.fetus , C. coli, C. lari Bacteria: gram negative rod, LOS, enterotoxin (≈cholera toxin), thermophilic (42 *C) ROT: ingestion of infected poultry or contaminated water, fecal -oral Campylobacteriosis (enteritis): infection 1-7days after ingestion, lasts several weeks, self limited D iarrhea (may be bloody), myalgia, high fever, abdominal cramping, headache Complications- reactive arthritis, septic abortion, bacteremia , Guillain-Barre syndrome Treatment Fluid and electrolyte replacement Severe disease: ciprofloxacin / ceftriaxone

10. Vibrio spp Species: V. cholera serogroup O1 and non-O1, V. parahemolyticus Bacteria: gram negative rod, curved, cholera toxin (AB toxin), acid labile toxin ROT: ingestion of uncooked seafood, water transmission V. cholerae serogroup O1 causes epidemic cholera (1. Classical, 2. El Tor) V. cholerae non- O1 cause milder cholera-like illnesses Cholera: massive fluid and electrolyte loss through watery diarrhea and uncontrollable vomiting, incubation period is days to weeks, untreated dehydration leads to hypovolemic shock and death in 50% of the patients Treatment Fluid and electrolyte replacement Occasionally doxycycline / ciprofloxacin, prophylactic vaccine is available

11. Yersinia spp Species: Y. enterocolitica , Y. pseudotuberculosis Bacteria: gram negative coccobacilli, grow best at 25*C, grow in refrigerators at 4*C as well ROT: ingestion of infected raw pork Yersiniosis : enterocolitis with fever, watery or bloody diarrhea and abdominal cramping, usually in children formation of ulcerative lesions in the terminal ileum, necrotic lesions in the peyer’s patches, invades mesenteric lymph nodes and swells them ( pseudoappendicitis ) Complications: reactive arthritis, erythema nodosum , Treatment Symptomatic Severe disease: doxycycline / trimethoprim-sulfamethoxazole / streptomycin / fluoroquinolone

12. Clostridium difficile Bacteria: gram positive anaerobic rod, minor normal flora, AB toxin ROT: fecal -oral, contagious spores in dust, flora overgrowth Clostridial diarrhea is a complication of antibiotic therapy, mostly from gentamycin, ampicillin and cephalosporins Ranging from simple watery stools to life-threatening pseudomembranous colitis (PMC) Treatment Discontinuation of the drug Metronidazole / vancomycin

13. Diagnosis Clinical (symptomatic) Microbiological Microbe cultivation in selective agars from stool samples Sugar fermenting patterns (lactose, glucose, fructose) Serology (antigen/antibodies) Blood culture ( bacteremia /sepsis) DNA amplification methods (PCR) Enzyme tests (oxidase, catalase)