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GI INFECTIONS

GI INFECTIONS. Brenda Beckett, PA-C Clinical Medicine II. GI Infections. Gastroenteritis Viral Hepatitis. Gastroenteritis. Diarrhea, vomiting, cramping Increased fluid output, more than 4-5, watery bowel movements per day Acute diarrhea – symptoms for less than 2 weeks

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GI INFECTIONS

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  1. GI INFECTIONS Brenda Beckett, PA-C Clinical Medicine II

  2. GI Infections • Gastroenteritis • Viral Hepatitis

  3. Gastroenteritis • Diarrhea, vomiting, cramping • Increased fluid output, more than 4-5, watery bowel movements per day • Acute diarrhea – symptoms for less than 2 weeks • Exception: C. diff sx can last longer

  4. Pathophysiology • Viruses damage the small intestinal villi, decreasing intestinal surface area and unmasking ongoing fluid secretion by enteric crypts • Rotavirus produces an enterotoxin that induces secretion and contributes to the watery diarrhea

  5. Pathophysiology • Invasive bacteria cause mucosal ulceration and abscess formation with an inflammatory response (WBCs in stool) • Bacterial toxins may influence enteric and extraenteric cellular processes (HUS, etc) • Other noninvasive bacteria and protozoa adhere to the gut wall, causing inflammation

  6. Patient Evaluation • Duration of symptoms • Quantity (frequency of stools) • Quality (watery) • Fever • Hematochezia – visible blood in stool • S/S of dehydration • Other sx: N/V, abd pain, tenesmus, anorexia • Recent travel, recent abx use, hepatitis risk • Other family members sick? • Ability to take PO fluids

  7. Physical Exam • Jaundice • Hydration status – check for signs of dehydration • Stool Guaiac – occult blood • Abdominal tenderness, bowel sounds • Mental status

  8. Oral Rehydration • Replace water, salt, sugars lost due to diarrhea, vomiting • In mildly dehydrated patient, it is first line therapy before IV rehydration. • Formulas are based on patient weight, degree of dehydration • 75 ml/kg over 4 hrs every 2 min

  9. Enteric Illness, categories • Non-specific gastroenteritis • Gastroenteritis with bloody diarrhea • Extraintestinal illness • Non-infectious causes of GI symptoms

  10. Nonspecific Gastroenteritis • Diarrhea without high fever or bloody stool • May have: cramps, low grade fever, headache, malaise, dehydration, N/V • Etiology: Viral (Norwalk-like viruses, Rotavirus), protozoal (giardia, crypto), foodborne toxins (S. aureus), traveller’s diarrhea, noninfectious causes.

  11. Gastroenteritis with bloody diarrhea • Bloody stools with fever, +/- vomiting: Consider Salmonella, Shigella, Campylobacter (bacterial) • Bloody stools without fever: Could be above or E. coli 0157:H7.

  12. GI illness with Extraintestinal Disease • Jaundice: Hepatitis A (we’ll get there in a little bit) • Meningitis: Listeria, salmonella • Arthritis: Campylobacter, salmonella • Flaccid paralysis and cranial neuropathies: C. botulinum (Botulism) • HUS: E. coli 0157:H7

  13. Noninfectious causes of GI sx • Otitis media, Group A Streptococcal infection, irritable bowel syndrome, inflammatory colitis, stress, medications, gallbladder disease, peptic ulcer disease

  14. Staphylococcal Food Toxin • S/S: Vomiting, severe cramping, low grade fever, diarrhea (no blood in stool) • Incubation: VERY short – 30 minutes to a few hours. • Complications: None, spontaneous recovery • Diagnosis: No specific test available. Clinical dx.

  15. Staphylococcal Food Toxin • Treatment: Supportive – rest, hydration, compazine or other antiemetic for persistent vomiting • Origin: Toxin producing S. aureus strains, usually from human skin, inoculate food, multiply at room temp. Toxins not destroyed by reheating. • Other toxin producing bacteria: Clostridium perfringens, Bacillus cereus.

  16. Staphylococcal Food Toxin • Prevention • Decrease food handling • Do not allow foods to sit at room temp. for long periods • Glove use by food handlers • Exclude persons from food handling when obvious skin infections are present.

  17. Salmonella • Agent: Multiple subtypes of Salmonella species (S. enteritidis, S. typhimurium are most common) • Reservoir: Birds (chickens, turkeys), reptiles, others • Occurrence: Common • Transmission: Undercooked meat/eggs, cross contamination by meat juices, unpasteurized milk, handling reptiles

  18. Salmonella • Incubation: 6-72 hours (usually 10-12) • Diagnosis: Stool culture • Clinical: Diarrhea, often bloody, fever, cramps, vomiting • Complications (elderly, immunocomp.): Arthritis, meningitis, sepsis. • Treatment: Usually supportive. Quinolones if severe or if immunocompromised.

  19. Campylobacter • Agent: C. jejuni • Reservoir: Poultry, cattle, others • Occurrence: Common • Transmission: Undercooked poultry, cross contamination, unpasteurized milk • Incubation: 3-5 days • Diagnosis: Stool culture

  20. Campylobacter • Clinical: Diarrhea (often bloody), severe cramps, fever, +/- vomiting • Complications: Arthritis, cholecystitis • Treatment: Quinolones or erythromycin • Prevention: Adequate cooking, kitchen hygiene, pasteurization

  21. E. Coli 0157:H7 • Agent: As above • Reservoir: Cattle (and foods contaminated with cow feces) • Occurrence: Less common than Salmonella and Campy, but increasing • Transmission: Ingestion of undercooked beef, cross contamination, unwashed contaminated fruits & veggies, person to person, water contamination. HIGHLY transmissible.

  22. E. Coli 0157:H7 • Incubation: 2-7 days • Clinical: Watery diarrhea progressing to bloody diarrhea after a few days. Fever usually absent. Cramps, vomiting. • Complications: 5-10% of kids younger than 5 will develop HUS, a life threatening multisystem disease. Can occur in adults.

  23. E. Coli 0157:H7 • Diagnosis: Stool culture, toxin assay • Treatment: Supportive. Antibiotics usually avoided (can increase HUS) • Prevention: Thorough cooking of ground beef, avoid cross contamination with beef juices, wash fruits/veggies, pasteurization. Early diagnosis will prevent person to person transmission.

  24. Shigella • Agent: S. sonnei, S. flexneri, others • Reservoir: Humans • Transmission: Person to person, foodborne, flies. • Clinical: Fever, bloody diarrhea, cramps, vomiting. Patients often appear toxic. • Diagnosis: Stool culture

  25. Shigella • Complications: Sepsis, meningitis • Treatment: Quinolones, hydration • Communicability: Extremely high • Prevention: Early diagnosis and isolation, hand washing, food and water hygiene • Occurrence: Rare locally, high in third world countries.

  26. Clostridium difficile • Most common antibiotic associated diarrhea- due to changes in colonic bacterial fermentation of carbohydrates • Colitis associated with toxin produced by C. diff. • Hospitalized, immunocompromised are most susceptible

  27. Clostridium difficile • Antibiotics disrupt the normal flora, C. diff. flourishes (carried asymptomatically by 3-8% healthy adults). Any abx can trigger, but most common are: cephalosporins, penicillins, clindamycin, flouroquinolones • Sx start during or after abx therapy, may be delayed 8 weeks • Easily transmitted in hospital setting

  28. Clostridium difficile • Toxins (A- enterotoxin & B-cytotoxin) have effect on colon- secretes fluid, develops pseudomembranes (discrete yellow-white plaques), easily dislodged. • Diagnosed by C. diff toxins in stool. EIA rapid toxin A & B. • Treat with Metronidazole 500 mg po tid x10-14 d. D/c other abx if possible. • Infection control measures to reduce spread in hospital settings.

  29. Viral Gastroenteritis • Most common cause of infectious diarrhea in US • Infect epithelium of small intestine • Diarrhea is watery • WBC’s and visible blood are rare • 4 categories: Rotavirus, Claicivirus (norovirus), Astroviurs, Enteric Adenovirus.

  30. Rotavirus • Most common cause of diarrhea in young children • Highly contagious: fecal-oral. • Incubation 1-3 days, lasts 4-8 days • Dehydration and hospitalization common in young children • Diagnose by EIA antigen in stool • Treat with oral rehydration or IV • Oral vaccine now available (controversial)

  31. Calcivirus • Infect older children and adults • Nonspecific, self-limiting • Large water-borne and food-borne outbreaks occur, fecal-oral • Incubation 24-48 hrs, lasts 12-60 hrs • No commercial tests to diagnose • Treatment supportive (oral rehydration)

  32. Giardiasis • Agent: Giardia lamblia • Reservoir: Human and animal stool • Occurrence: Very common • Transmission: fecal-oral, contaminated water or food • Incubation: 3-10 days

  33. Giardiasis • Clinical: Persistent or recurring diarrhea, bloating, cramps, steatorrhea (frothy fatty stool), weight loss. No blood in stool. • Diagnosis: Ova and parasite slide or direct antigen test. • Treatment: Metronidazole or other antiparasitic • Prevention: Water filtration, avoid drinking untreated surface water.

  34. Traveler’s Diarrhea • Usually caused by endemic bacteria, not one specific agent. Most common is E. coli. • Usually benign, self-limiting • Prophylactic abx for immunocomp. • Treat with flouroquinolone if bloody diarrhea and fever

  35. Changing gears…

  36. Hepatitis - Causes • Drugs: antihypertensives, statins, antibiotics, others. • Toxic agents: acetaminophen, alcohol, others. • Viruses: Hepatitis A (HAV), B (HBV), C (HCV) commonly. Uncommon: EBV, CMV, measles, rubella, etc.

  37. Hepatitis – Clinical Presentation • Anorexia • Malaise • N/V • Fever • Enlarged, tender liver • Jaundice • Abnormal liver enzymes

  38. Liver Function Tests • Serum Aminotransferases (ALT and AST). ALT usually >8x upper limit of normal • Serum and urine Bilirubin. (Neither sensitive nor specific for viral hepatitis) • Serum Alkaline Phosphatase • Additionally: LDH, GGTP, Albumin, Prothrombin Time

  39. Lab and Physical Findings • In viral hepatitis ALT is usually higher than AST, as opposed to alcoholic hepatitis • Many people are entirely asymptomatic or mildly symptomatic with jaundice (especially HBV and HCV infections) • Children <6yrs with acute HAV infection are usually asymptomatic, rarely jaundiced • Table p 238-239 Wallach.

  40. Acute Viral Hepatitis • Any combination of: malaise, fever, nausea, vomiting, abdominal pain or fullness, diarrhea, myalgias, headache. • Can have +/- jaundice, dark urine • ANDabrupt, dramatic elevation of ALT/AST • Hepatitis serologies to diagnose, discussed in lab lecture.

  41. Hepatits A • Most common cause of acute viral hepatitis • Small RNA picornavirus • About 30 day incubation • Fecal-oral transmission • Epidemics or sporadic cases • Source: contaminated water, food (shellfish) • No chronicity, no carrier state

  42. Hepatitis A • Most children asymptomatic, most adults symptomatic • Low mortality • Excreted in feces up to 2wks before illness, rarely after first week of illness • Only viral hepatitis causing spiking fevers • Viremia intermittent

  43. Hepatitis A Vaccine • Available since the mid 1990’s • Recommended for: • children 12-23 months • International travelers • People who live or work where there are outbreaks • Some other high risk groups

  44. Hepatitis A Treatment • Symptomatic treatment (rest, fluids, etc) • Avoid strenuous physical exertion, alcohol and hepatotoxins • IG given to close contacts • Vaccination of close contacts

  45. Hepatitis B • Second most common cause of acute viral hepatitis • dsDNA Hepadnaviridae • Most complex hepatitis virus • Infective particle made up of viral core plus an outer surface coat • Transmission: sexual, parenteral, perinatal

  46. Hepatitis B • Can become chronic (5-10% of acute), may result in cirrhosis, hepatocellular ca • Often asymptomatic or nonspecific symptoms • Incubation 6-12 weeks • If recover from HBV infection, will be immune

  47. Hepatitis B Vaccination • Available since the 1980’s • Routine childhood vaccine (3 doses) • Given at birth to babies of HBsAg pos mothers • Anti-HBs response • Other high risk groups • Post exposure prophylaxis: HBIG and start vaccine

  48. Hepatitis B Treatment • HBIG given within 7 days of exposure • Initiation of HBV vaccine series • Symptomatic treatment (rest, fluids, etc) • Avoid strenuous physical exertion, alcohol and hepatotoxins

  49. Hepatitis C • Single-stranded RNA flavivirus • 6 major subtypes with varying genotypes • Primarily transmitted by blood • Injection drug use >50% of cases • Posttransfusion, hemodialysis, tattoos, body piercing • Sexual and vertical transmission uncommon, but increased risk with multiple sex partners. • HIV patients at increased risk

  50. Hepatitis C • Incubation period: 6-7 weeks avg, ranges from 2-26 weeks • Clinical illness often mild, asymptomatic • Chronicity common: >70%, may progress to cirrhosis, carcinoma • Leading cause of liver transplant • No protective antibody response

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