Transcript GI Infections

GI INFECTIONS
Brenda Beckett, PA-C
Clinical Medicine II
GI Infections
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Gastroenteritis
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Viral Hepatitis
Gastroenteritis
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Diarrhea, vomiting, cramping
– Increased fluid output, more than 4-5,
watery bowel movements per day
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Acute diarrhea – symptoms for less
than 2 weeks
– Exception: C. diff sx can last longer
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
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Pathophysiology
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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
Patient Evaluation
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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
Physical Exam
Jaundice
 Hydration status – check for signs of
dehydration
 Stool Guaiac – occult blood
 Abdominal tenderness, bowel sounds
 Mental status
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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
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Enteric Illness, categories
Non-specific gastroenteritis
 Gastroenteritis with bloody diarrhea
 Extraintestinal illness
 Non-infectious causes of GI symptoms
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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.
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Gastroenteritis with bloody
diarrhea
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Bloody stools with fever, +/- vomiting:
Consider Salmonella, Shigella,
Campylobacter (bacterial)
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Bloody stools without fever: Could be
above or E. coli 0157:H7.
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
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Noninfectious causes of GI sx
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Otitis media, Group A Streptococcal
infection, irritable bowel syndrome,
inflammatory colitis, stress,
medications, gallbladder disease, peptic
ulcer disease
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.
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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.
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Staphylococcal Food Toxin
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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.
Salmonella
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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
Salmonella
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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.
Campylobacter
Agent: C. jejuni
 Reservoir: Poultry, cattle, others
 Occurrence: Common
 Transmission: Undercooked poultry,
cross contamination, unpasteurized milk
 Incubation: 3-5 days
 Diagnosis: Stool culture
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Campylobacter
Clinical: Diarrhea (often bloody), severe
cramps, fever, +/- vomiting
 Complications: Arthritis, cholecystitis
 Treatment: Quinolones or erythromycin
 Prevention: Adequate cooking, kitchen
hygiene, pasteurization
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E. Coli 0157:H7
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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.
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.
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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.
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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
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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.
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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
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Clostridium difficile
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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
Clostridium difficile
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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 x1014 d. D/c other abx if possible.
 Infection control measures to reduce spread
in hospital settings.
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.
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Rotavirus
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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)
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)
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Giardiasis
Agent: Giardia lamblia
 Reservoir: Human and animal stool
 Occurrence: Very common
 Transmission: fecal-oral, contaminated
water or food
 Incubation: 3-10 days
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Giardiasis
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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.
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
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Changing gears…
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.
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Hepatitis – Clinical Presentation
Anorexia
 Malaise
 N/V
 Fever
 Enlarged, tender liver
 Jaundice
 Abnormal liver enzymes
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Liver Function Tests
Serum Aminotransferases (ALT and
AST). ALT usually >8x upper limit of normal
 Serum and urine Bilirubin. (Neither
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sensitive nor specific for viral hepatitis)
Serum Alkaline Phosphatase
 Additionally: LDH, GGTP, Albumin,
Prothrombin Time
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Lab and Physical Findings
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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.
Acute Viral Hepatitis
Any combination of: malaise, fever,
nausea, vomiting, abdominal pain or
fullness, diarrhea, myalgias, headache.
 Can have +/- jaundice, dark urine
 AND abrupt, dramatic elevation of
ALT/AST
 Hepatitis serologies to diagnose,
discussed in lab lecture.
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Hepatits A
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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
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
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Hepatitis A Vaccine
Available since the mid 1990’s
 Recommended for:
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– children 12-23 months
– International travelers
– People who live or work where there are
outbreaks
– Some other high risk groups
Hepatitis A Treatment
Symptomatic treatment (rest, fluids, etc)
 Avoid strenuous physical exertion,
alcohol and hepatotoxins
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IG given to close contacts
 Vaccination of close contacts
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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
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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
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Hepatitis B Vaccination
Available since the 1980’s
 Routine childhood vaccine (3 doses)
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– Given at birth to babies of HBsAg pos
mothers
Anti-HBs response
 Other high risk groups
 Post exposure prophylaxis: HBIG and
start vaccine
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Hepatitis B Treatment
HBIG given within 7 days of exposure
 Initiation of HBV vaccine series
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Symptomatic treatment (rest, fluids, etc)
 Avoid strenuous physical exertion,
alcohol and hepatotoxins
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Hepatitis C
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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
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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Hepatitis C
Prolonged viremia
 Aminotransferases will be elevated off
and on (can have ALT >7x normal)
 Diagnose with Anti-HCV EIA
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Hepatitis C Treatment
Interferon or peginterferon for 6-24
weeks decreases risk of chronicity
 May reserve treatment for those that do
not clear virus in 3-4 months (monitor
HCV-RNA). Clearance more likely in
symptomatic than asymptomatic pts.
 Liver transplantation in acute liver
failure
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Hepatitis C
NO immunization
 No post exposure prophylaxis
 Chronicity common
 Different genotypes respond differently
to therapy
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Other Hepatitis Viruses
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Hepatitis D (Delta).
– Due to ssRNA virus.
– Always associated with Hepatitis B.
– Acute or chronic.
– Often severe, high mortality.
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Hepatitis E. Due to ssRNA virus.
– Rare, occurs in endemic areas.
Chronic Hepatitis
HBV – 5-10% of acute infections
 HCV - >70% of acute infections
 HDV – with HBV coinfection or
superinfection
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Chronic Hepatitis
Elevated aminotransferases for more
than 6 months
 May lead to cirrhosis, hepatocellular
carcinoma
 Liver transplantation indicated for endstage disease
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