15-month-old with vomiting, diarrhea, and poor appetite
Patient will present as → an 11-year-old boy who is brought to the clinic for diarrhea and vomiting. He has no fever but complains of intermittent, cramping, and abdominal pain. They just returned from a family picnic, where about two hours ago the child ate potato salad. The mother reports other family members had become ill after the meal as well.
To watch this and all of Joe-Gilboy PA-C's video lessons you must be a member. Members can log in here or join now.
Causes of diarrhea may be infectious, toxic, dietary (excessive laxative use) or other GI disease. Inflammatory diarrhea (bloody diarrhea with fever) indicates an invasive organism or inflammatory bowel disease.
- Traveler's diarrhea: e-coli
- Diarrhea after a picnic and egg salad: Staphylococcus Aureus
- Diarrhea from shellfish: Vibrio cholerae
- Diarrhea from poultry or pork: Salmonella
- Diarrhea in a patient post antibiotics: C. Difficile
- Diarrhea in poorly canned home foods: C. perfringens
- Diarrhea breakout in a daycare center: Rotavirus
- Diarrhea on a Cruise Ship: Norovirus
- Diarrhea after drinking (not so) fresh mountain stream water: Giardia lamblia - incubates for 1-3 weeks, causes foul-smelling bulky stool and may wax and wane over weeks before resolving
White blood cells in stool indicate an inflammatory process
- Culture for bacterial agents, microscopy for parasites or toxin identification (E Coli or C.diff is suspected)
Acute diarrhea (< 4 days) typically does not require testing. Exceptions are patients with signs of dehydration, bloody stool, fever, severe pain, hypotension, or toxic features—particularly those who are very young or very old.
These patients should have a CBC and measurement of electrolytes, BUN, and creatinine.
Stool samples should be collected for microscopy, culture, fecal leukocyte testing, and, if antibiotics have been taken recently,C. difficile toxin assay.
Severe diarrhea requires fluid and electrolyte replacement to correct dehydration, electrolyte imbalance, and acidosis.
Parenteral fluids containing NaCl, KCl, and glucose are generally required. Salts to counteract acidosis (Na lactate, acetate, HCO 3 ) may be indicated if serum HCO 3 is < 15 mEq/L. An oral glucose-electrolyte solution can be given if diarrhea is not severe and nausea and vomiting are minimal. Oral and parenteral fluids are sometimes given simultaneously when water and electrolytes must be replaced in massive amounts (eg, in cholera).
Diarrhea is a symptom. When possible, the underlying disorder should be treated, but symptomatic treatment is often necessary.
Diarrhea may be decreased by
- oral loperamide 2 to 4 mg tid or qid (preferably given 30 min before meals)
- diphenoxylate 2.5 to 5 mg (tablets or liquid) tid or qid
- codeine phosphate 15 to 30 mg bid or tid
- or paregoric (camphorated opium tincture) 5 to 10 mL once/day to qid.
Because antidiarrheals may exacerbate C. difficile colitis or increase the likelihood of hemolytic-uremic syndrome in Shiga toxin-producing Escherichia coli infection, they should not be used in bloody diarrhea of unknown cause. Their use should be restricted to patients with watery diarrhea and no signs of systemic toxicity. However, there is little evidence to justify previous concerns about prolonging excretion of possible bacterial pathogens with antidiarrheals.
![]() |
|
![]() |
![]() |
Rotavirus is a non-enveloped, double-stranded, linear RNA virus that is the most common cause of severe diarrhea in infants and young children. This virus is in the family of reoviridae and contains a segmented genome of 10-12 segments. Each gene segment encodes for one protein, except segment 9, which codes for two. The RNA is surrounded by a triple icosahedral protein capsid, and viral particles are not enveloped. By five years of age, nearly every child in the word has been infected with rotavirus at least once. With each infection, immunity develops and following infections are less severe. Therefore, adults are rarely affected. The virus is transmitted via fecal-oral route and damages the lining of the small intestine, leading to villous atrophy. The incidence of disease is more common in winter months and in day care centers from increased fecal-oral contact. The disease is usually easily managed, but more than 450,000 children under five years old continue to die from rotavirus infection each year in developing countries. Public health campaigns focus on oral rehydration therapy for management of disease. |
![]() |
Norovirus is a genus of virus in the calicivirus family, which leads to acute gastroenteritis in the infected. It is the most common cause of viral gastroenteritis in the world, and disease is typically self-limited. |
![]() |
Salmonella enterica spp. is a gram negative rod that causes salmonellosis. Animals and humans can both serve as reservoirs for this bacterium; it can also be spread through uncooked poultry and raw eggs. Patients infected with Salmonella enterica have an immune responsive increase in PMNs. Symptoms of salmonellosis include GI distress, with potentially bloody diarrhea. Antibiotics are not recommended for treatment, as they prolong the carrier state. Moreover, there are no vaccines to prevent this infection, unlike Salmonella typhi. |
![]() |
Clostridium difficile is a gram-positive bacilli of the genus Clostridium, which are anaerobic, spore forming bacteria. This bacteria is known to cause severe diarrhea and other intestinal disease when the normal gut flora is killed by antibiotics, allowing proliferation of Clostridium difficile in the gut. Clostridium difficile releases two toxins that can damage the intestine. Toxin A is an enterotoxin that damages the brush border of the gut, and toxin B is a cytotoxin that induces actin depolymerization, leading to damage of the cytoskeletal structure. Together, these toxins are responsible for the inflammation and diarrhea seen in infected patients. Clostridium difficile infections almost always occur after use of broad-spectrum antibiotics like clindamycin or ampicillin. The use of antibiotics destroy the normal gut flora, allowing the gut to become overrun with C. difficile with release of large amounts of toxin. C. difficile infections are the most common cause of pseudomembranous colitis and can also lead to toxic megacolon in extreme cases. Because this bacteria is part of the normal gut flora in many patients, Clostridium difficile infection should be diagnosed via detection of toxins in the stool as opposed to culture. Treatment includes metronidazole and vancomycin. |
![]() |
Giardia lamblia is a protozoan parasite that infects the small intestine, causing giardiasis. The life cycle of Giardia begins with a cyst that is excreted in the feces of an infected individual. The cyst can survive for weeks to months, and can contaminate food or water sources. In addition to food and water sources, fecal-oral transmission can occur. This is commonly observed in day care centers or mental hospitals. where there may be poor hygiene practices. Once ingested by a host, trophozoites are released in an active state in the small intestine and undergo replication via binary fission. Colonization of the gut results in severe inflammation and villous atrophy, causing reduced absorptive capability. Symptoms of infection include bloating, flatulence and foul-smelling, fatty diarrhea. This condition is usually self-limiting but can cause prolonged symptoms in the immunocompromised. Individuals with lack of IgA are especially prone to recurring Giardia infections and can develop chronic disease. Metronidazole is the current first-line therapy for Giardia infections. |
![]() |
Clostridium perfringens is a species of the clostridia genus, a group of gram-positive, spore-forming bacteria. C. perfringens is a non motile bacillus that prefers to grow in an anaerobic environment and is capable of forming spores when in an unfavorable environment. It is known for its quick onset of disease, as it can multiply in less than a day and causes disease in skin and soft tissue, or the GI tract. This bacteria produces hydrogen and carbon dioxide as a byproduct of its replication, which results in the characteristic gas formation in tissues. C. perfringens is also known for its ability to produce multiple exotoxins. The most clinically important toxin is alpha toxin, which contains a phospholipase that is capable of destroying phospholipids. In particular, the phospholipid lecithin, which is in cell walls of RBCs, WBCs, and muscle cells, can be damaged. This produces the characteristic hemolysis and myonecrosis. The myonecrosis with accompanying gas formation is known as gas gangrene. C. perfringens produces multiple other pathogenic toxins, including heat-labile enterotoxin which causes clostridial food poisoning manifested by abdominal pain and diarrhea. The typical scenario involves meat that is kept warm for long periods of time, allowing spores to germinate and produce bacteria in a vegetative state that produce the enterotoxin. Clostridial food poisoning is rarely fatal, but gas gangrene can be rapidly lethal and lead to shock unless treated. Placement of the patient in a hyperbaric oxygen chamber can increase the oxygen content of tissues, and slow the rate of growth of bacteria. Debridement of dead tissue is essential. Antibiotics may also be useful. |
![]() |
Staphylococcus aureus is a gram-positive cocci that literally means “golden grape cluster berry” due to its clustered appearance on gram stain. It is frequently found as normal flora on the skin and nasal passages but can cause a wide range of illnesses from minor skin infections to life-threatening diseases like pneumonia, osteomyelitis, and endocarditis. Staph aureus can cause a variety of skin infections including pimples, impetigo, furuncles, cellulitis, and abscesses. It can also cause severe pneumonia. Individuals are particularly susceptible to pneumonia caused by Staph aureus following viral influenza. This bacteria can also cause disease mediated by toxins. Some strains produce the exotoxin TSST-1, which causes toxic shock syndrome. This toxin acts as a super antigen which simultaneously binds MHC II and T cell receptors causing polyclonal T cell activation. Some strains produce an enterotoxin causing food poisoning. Staph aureus food poisoning presents as a rapid onset of symptoms due to ingestion of preformed toxins. Some produce exfoliative toxin, which are proteases that cleave desmoglein-1, which can cause detachment of the granulosum and spinosum layers in the epidermis. Staph aureus can also cause a life threatening acute bacterial endocarditis and osteomyelitis. |
![]() |
Enterohemorrhagic Escherichia coli (EHEC), commonly called E. coli O157:H7 is an important cause of foodborne illness in the United States. In addition to bloody diarrhea, individuals can develop hemolytic uremic syndrome with anemia, thrombocytopenia, and acute renal failure, especially in young children and elderly persons. This bacterial strain is most commonly transmitted via the fecal-oral route and typically associated with eating contaminated ground beef in undercooked hamburgers. It is a specific serotype of E. coli. The O refers to the cell wall antigen water, while H refers to the flagella antigen. This strain may produce Shiga-like toxin, which catalytically inactivates the 60S ribosomal subunit of eukaryotic cells. This blocks mRNA translation and causes cell death in the mucosal cells of the GI tract. The toxin also enhances cytokine release, which can cause hemolytic uremic syndrome (HUS). Strains of E. coli that express Shiga-like toxins gained this ability through lysogeny, meaning infection with a prophage that contained the coding for the toxin. E. coli O157:H7 can be differentiated from other E. coli strains because it is typically non-sorbitol fermenting, whereas the majority of other E. coli strains are sorbitol fermenters. In patients, antibiotics are not part of the treatment of patients with EHEC disease and may possibly increase the risk of subsequent HUS. As toxins may be released by dead and dying bacterial cells, the risk of endotoxin release could add to the patient's already potentially lethal burden. |
Question 1 |
Salmonella | |
Staphylococci Hint: Causes diarrhea following ingestion of improperly stored food with high salt content. | |
C. perfringens Hint: Causes diarrhea following ingestion of inadequately cooked meat, poultry, or legumes. | |
Giardia lamblia Hint: Causes diarrhea following ingestion of contaminated water. |
Question 2 |
Salmonella Hint: Is a cause of diarrhea following food poisoning. | |
Rotavirus Hint: Is a common cause of diarrhea in children. Less common in adults. Doesn’t occur as a result of recent use of antibiotics. | |
Clostridium difficile | |
E. coli Hint: Is a cause of diarrhea following food poisoning. |
Question 3 |
Empirical antibiotic therapy. Hint: Not necessary as the diarrhea is likely not infectious/non inflammatory. | |
Prescribe an antidiarrheal agent. | |
Stool culture. Hint: See B for explanation | |
Stool for ova and parasite. Hint: See B for explanation |
Question 4 |
Oral rehydration | |
Intravenous rehydration | |
Stool culture | |
Empirical antibiotics |
Question 5 |
45 mmol Na+, 20 mmol K+, 70 mmol Cl−, 100 mmol citrate, and 110 mmol glucose | |
50 mmol Na+, 30 mmol K+, 80 mmol Cl−, 10 mmol citrate, and 100 mmol glucose | |
90 mmol Na+, 20 mmol K+, 80 mmol Cl−, 10 mmol citrate, and 111 mmol glucose | |
90 mmol Na+, 30 mmol K+, 80 mmol Cl−, 20 mmol citrate, and 111 mmol glucose |
Question 6 |
Salmonella | |
Shigella | |
Campylobacter | |
Escherichia coli | |
Enterococcus |
Question 7 |
Shigella | |
Salmonella | |
enteroinvasive E. coli | |
all of the above |
Question 8 |
infection is transmitted by undercooked ground beef, unpasteurized milk, and other vehicles contaminated with bovine feces Hint: See C for answer | |
outbreaks have been linked to contaminated apple cider, raw vegetables, and drinking water Hint: See C for answer | |
person-to-person transmission is uncommon in outbreaks | |
the dose necessary to cause infection is low Hint: See C for answer | |
hemolytic-uremic syndrome is a serious complication of infection Hint: See C for answer |
Question 9 |
ampicillin | |
clindamycin | |
amoxicillin | |
cephalosporins | |
all of the above |
Question 10 |
attempt oral rehydration therapy Hint: See C for explanation | |
perform a venous cutdown in the ankle Hint: See C for explanation | |
begin an interosseous infusion | |
begin a subcutaneous infusion Hint: See C for explanation |
Question 11 |
urine specific gravity Hint: See D for explanation | |
stool evaluation for blood Hint: See D for explanation | |
stool evaluation for fecal leukocytes Hint: See D for explanation | |
stool cultures | |
serum electrolytes Hint: See D for explanation |
Question 12 |
Metronidazole (Flagyl) | |
Diphenoxylate/atropine (Lomotil) Hint: See A for explanation | |
Clindamycin (Cleocin) | |
Ciprofloxacin (Cipro) |
List |