Intestinal infection in a newborn: symptoms and treatment

A newborn's normal stool differs from that of older children: infants often have loose, mushy, or even watery, mustard-yellow stools, which can occur 8-12 times a day—and this is normal. Diarrhea at this age is defined as a sharp increase in bowel movements compared to the usual, with a distinctly watery consistency, a change in odor, mucus or blood, a deterioration in overall health, and signs of dehydration. It's important to first distinguish normal, loose stools in infants from true diarrhea. [1]

The danger of diarrhea in newborns is primarily associated with the rapid development of dehydration: at this age, water reserves are low and metabolism is high. The severity of dehydration is assessed by a combination of signs: lethargy, sunken eyes, poor sucking or refusal to drink, and slow straightening of the skin fold. These signs form the basis of international algorithms and are required for choosing a rehydration plan. [2]

Any fever in a child under 3 months is a serious sign. A body temperature of 38.0°C or higher at this age requires a doctor's examination to rule out a severe bacterial infection and dehydration, even if there are signs of an intestinal infection. [3]

In the first weeks of life, diarrhea can mask other medical emergencies. Danger signs include green vomit, severe abdominal distension, lethargy, mottled skin, blood in the stool, infrequent urination, and lack of tears when crying. If these symptoms appear, immediate medical attention is required. [4]

Early initiation of proper rehydration and continued breastfeeding reduce the risk of hospitalization and speed recovery. The key approach is early administration of low-osmolarity oral rehydration solutions and continued breastfeeding. [5]

Table 1. Norm against diarrhea in infants

Sign	Normal for a breastfed baby	Diarrhea
Stool frequency	From after each feeding to once every 2-3 days	A sharp increase in frequency relative to the usual regime
Consistency	Liquid, mushy, may be watery	Watery "like water", with a pungent odor
Color	Mustard yellow, may be greenish	Any, but especially with an admixture of blood, discolored
General condition	Active, sucks well, gaining weight	Lethargy, refusal to breastfeed, signs of dehydration
Additional signs	The skin and mucous membranes are moisturized, there are tears	Dry mucous membranes, infrequent urination, no tears
[6]

Causes and risk factors in newborns

Viral gastroenteritis is less common in full-term newborns than in older children, but outbreaks of norovirus and rotavirus infections are possible. In some infants, viral infections are milder due to passive maternal antibodies, but the risk of severe disease is higher in weakened and premature infants. [7]

Bacterial causes at this age include salmonellosis, shigellosis, campylobacteriosis, and pathogenic Escherichia coli. Children under 3 months of age have an increased risk of bacteremia and focal lesions with nontyphoidal salmonellosis infection, so the treatment approach differs from that in older children. [8]

A particular risk group is associated with artificial feeding with powdered formula, as powdered formulas are not sterile. Preparing the formula with water at a temperature of at least 70°C significantly reduces the risk of contamination with dangerous microorganisms such as Cronobacter. For newborns with increased risk, sterile, ready-to-use liquid formulas are preferred. [9]

Non-drug risk factors include poor hand and personal hygiene, improper storage and dilution of formula, contact with sick people, and consumption of unsafe water. Adherence to hygiene rules at home and in hospitals significantly reduces the risk of intestinal infection. [10]

Non-infectious diarrhea symptoms include cow's milk protein intolerance, transient lactase deficiency following an intestinal infection, drug-induced diarrhea following antibiotics, and rarer congenital electrolyte transport disorders. These conditions require medical evaluation in cases of prolonged or recurrent diarrhea. [11]

Table 2. Common causes of diarrhea in newborns and key clues

Group of reasons	Examples	Clues in the anamnesis
Viruses	Norovirus, rotavirus	Contact with sick people, vomiting, rapid onset
Bacteria	Salmonella, Shigella, Campylobacter, pathogenic Escherichia coli	Blood in stool, high fever, severe condition
Nutrition	Powder mixture, preparation error	Artificial feeding, failure to maintain temperature conditions
Intolerance	Cow's milk protein, transient lactase deficiency	Prolonged loose stools, rash, improvement with elimination
Other	Antibiotics, rare congenital syndromes	Medication intake, family history
[12]

Red Flags and When to Call Immediately

You should immediately contact a doctor if any of the following signs occur: age under 3 months with a temperature of 100.4°F (38.0°C) or higher, lethargy, refusal to breastfeed, infrequent urination, severe abdominal distension, green vomit, blood in the stool, seizures, or signs of shock. These symptoms are associated with a high probability of a serious infection or severe dehydration. [13]

Clinical signs of dehydration are assessed cumulatively. The following combinations are alarming: "lethargic or unconscious," "sunken eyes," "unable to drink or drinking poorly," "skin fold straightens very slowly." Any combination of two of these signs indicates severe dehydration and requires immediate care. [14]

Age under 6 months, blood in the stool, severe fever, immunodeficiency, and serious underlying illnesses are all indications for laboratory testing and, often, hospitalization. In newborns, the threshold for examination and observation is lower than in older children. [15]

Masquerading surgical and neonatal pathologies, such as necrotizing enterocolitis, require exclusion in the presence of abdominal distension, bloody stools, temperature instability, apnea, or severe lethargy. If such conditions are suspected, immediate inpatient evaluation is necessary. [16]

If the child appears toxic, shows signs of shock, or is unable to respond to oral rehydration, intravenous therapy is required in the hospital with electrolyte and hemodynamic monitoring. The decision is made by a physician after an in-person assessment. [17]

Table 3. Red flags in a newborn with diarrhea

Sign	What to do
Temperature of 38.0°C or higher in children under 3 months	See a doctor immediately
Lethargy, apathy, refusal to drink and breastfeed	See a doctor immediately
Blood in the stool or green vomit	See a doctor immediately
Severe abdominal distension, suspected pain	See a doctor immediately
Few wet diapers, no tears when crying	See a doctor immediately
[18]

Diagnostics: What the doctor asks and checks

The assessment includes questions about the duration of symptoms, the number of bowel movements and vomiting, contact with sick people, feeding method, the amount and method of formula preparation, the number of wet diapers, and associated symptoms. These elements help differentiate gastroenteritis from alternative diagnoses and assess risk. [19]

Physical examination focuses on assessing hydration, temperature, respiratory rate, heart rate, capillary refill, skin turgor, signs of pain, and abdominal distension. Recognizing the degree of dehydration based on clinical signs is the basis for management algorithms. [20]

Laboratory tests are not indicated for everyone. They are advisable in children under 6 months of age with fever, severe cases, blood in the stool, suspected bacterial infection or sepsis, and prolonged diarrhea. In these cases, a complete blood count, electrolytes, glucose, urine, and stool culture are considered, as indicated. [21]

Stool culture and molecular testing are recommended based on clinical indications rather than routine testing: in severe cases, in the presence of blood and mucus, during outbreaks, after travel, and in immunocompromised patients. For newborns, the threshold for testing is lower, given the risk of bacteremia. [22]

Instrumental methods are not required in typical cases of viral gastroenteritis. In newborns with "red flags," the physician considers abdominal imaging, radiography, inflammation tests, and other examinations to rule out surgical pathology. [23]

Table 4. When tests and inpatient observation are needed

Situation	Action
Age under 3 months and temperature of 38.0°C or higher	Doctor's examination, basic tests
Blood in the stool, high fever, suspected bacterial infection	Stool culture as indicated, blood tests, observation
Signs of severe dehydration	Hospitalization, rehydration under control
Immunodeficiency, severe concomitant pathology	Advanced diagnostics
Prolonged diarrhea of 14 days or more	Search for the causes of the protracted course
[24]

Home Treatment: Oral Rehydration Therapy and a Step-by-Step Plan

The mainstay of treatment is early oral rehydration with a low-osmolarity oral rehydration solution and continued normal feeding. Give the solution frequently and in small amounts using a spoon or syringe without a needle, especially if the child regurgitates. For mild to moderate dehydration, this is comparable in effectiveness to intravenous therapy and is safe. [25]

Approximate volumes: If signs of dehydration occur, approximately 50-100 ml per kg of body weight should be given to replenish the deficit over 4 hours, plus a maintenance volume. In practice, this is implemented as 10 ml per kg per hour in the first few hours, with a reassessment. If the child refuses, offer a teaspoon every 1-2 minutes. [26]

To compensate for ongoing losses after each episode of loose stool in children under 2 years of age, an additional 50-100 ml of solution is given. Alternatively, 10 ml per kg of body weight can be used after each episode of diarrhea. These volumes are added to the basic rehydration. [27]

If a child is vomiting constantly, refusing fluids, breastfeeding poorly, appears lethargic, or signs of dehydration are increasing, a physician's evaluation is required to decide on nasogastric or intravenous rehydration. The threshold for hospitalization is low in newborns. [28]

It's important to remember: sugary drinks, juices, broths, and plain water are not suitable for treating dehydration. A low-osmolarity oral rehydration solution (ORS) should be used. [29]

Table 5. Practical scheme of oral rehydration in a newborn

Step	What to do
1	Prepare the pharmaceutical solution strictly according to the instructions.
2	Give one teaspoon every 1-2 minutes or 10 ml per kg per hour
3	After each loose stool add 50-100 ml of solution or 10 ml per kg
4	Reassess the child's condition every 4 hours
5	If your condition worsens or you notice any red flags, see a doctor immediately.
[30]

Nutrition for diarrhea: breastfeeding and formula feeding

Breastfeeding should be continued and applied more frequently. Breast milk is better tolerated, provides water and electrolytes, and reduces the risk of prolonged symptoms. Stopping or diluting breast milk is not recommended. [31]

When formula-feeding, avoid diluting formula and routinely switching to lactose-free formulas. Most guidelines recommend maintaining a regular diet. Lactose-free formulas can be considered in hospital settings and with proven secondary lactase deficiency, but they are not the standard first-line treatment at home. [32]

The key to formula safety is proper preparation. Powdered formulas are not sterile, so to reduce the risk of Cronobacter, water should be brought to a boil and used for reconstitution at a temperature of at least 70°C, then cooled to feeding temperature. In the presence of high-risk factors, sterile liquid formulas are preferred. [33]

Do not use sugary drinks, juices, or decoctions instead of rehydration solution and main food. If vomiting occurs, feed more frequently and in smaller portions, adding small amounts of rehydration solution between feedings if necessary. [34]

Once dehydration is corrected, a normal feeding regimen is quickly returned. Early reintroduction of a normal diet accelerates intestinal mucosal recovery and reduces the duration of illness. [35]

Table 6. Nutrition for diarrhea in a newborn

Situation	Recommendation
Breast-feeding	Continue, apply more often
Artificial feeding	Keep the mixture as is, do not dilute it.
Lactose-free formula	Only for medical reasons, usually in a hospital setting
Additional drinking	Between feedings, small portions of rehydration solution
Safety of the mixture	Dilute with water not lower than 70 °C, observe hygiene
[36]

Medications: what helps and what is contraindicated

Zinc is a proven supportive therapy for diarrhea in children. The recommended dose for children under 6 months is 10 mg per day for 10-14 days. This reduces the duration and severity of the episode and reduces the risk of recurrence in the coming months. Prescription should be discussed with a physician, taking into account the child's age and feeding method. [37]

Probiotics are used with caution in newborns. Some strains have shown efficacy in older children, but cases of systemic fungal infections due to Saccharomyces have been reported in premature infants and infants with central catheters. The decision to prescribe any probiotics to newborns should be made by a physician, taking into account the individual risk. [38]

Antidiarrheal drugs that inhibit peristalsis are contraindicated in newborns due to the risk of serious side effects and masking of severe pathology. They are not used for acute diarrhea in young children. [39]

Antibacterial therapy is not routinely indicated and is prescribed only for specific indications. In exceptional situations, such as confirmed shigellosis dysentery or non-typhoidal salmonellosis infection in children under 3 months, antibacterial drugs may be required due to the risk of bacteremia. The decision is made by the physician based on the clinical presentation and test results. [40]

Antiemetic drugs should be used with extreme caution in infants and only as part of a medical intervention. When managing the condition at home, preference is given to frequent fluid intake and proper rehydration. [41]

Table 7. Medicines for diarrhea in newborns

Means	Role	Comments
Zinc	Reduces duration and severity	10 mg per day for 10-14 days as agreed with your doctor
Probiotics	Considered individually	Use with caution in newborns and premature infants
Antidiarrheal agents with a "stop" effect	Not applicable	Contraindicated
Antibiotics	According to the readings	For specific bacterial infections, as determined by the physician
Antiemetics	Only in a medical facility	Rarely used in newborns
[42]

Prevention

Breastfeeding protects against severe diarrheal illnesses and reduces the risk of dehydration. Supporting lactation and proper attachment are simple and effective prevention measures. [43]

Rotavirus vaccination, starting at 6 weeks of age, significantly reduces the incidence of severe gastroenteritis and hospitalizations in infants. Vaccination schedules are determined by national calendars, but the protective principle is universal. [44]

Safe preparation and storage of formula is critical: boil water, dilute at a temperature of at least 70°C, cool quickly to feeding temperature, use prepared formula within a reasonable time, and keep bottles and nipples clean. In high-risk situations, sterile, ready-to-use formulas are preferred. [45]

Hand hygiene for all caregivers, regular disinfection of food preparation surfaces and care items, safe drinking water, and avoidance of questionable home "solutions" are basic measures that truly prevent infection. [46]

Contact with sick people should be limited, especially in the first months of life. If signs of illness appear in family members, enhanced hygiene and separate use of towels and utensils are necessary. [47]

Table 8. Daily prevention

Measure	How to do it
Breast-feeding	Maintain exclusive breastfeeding whenever possible
Hand hygiene	Wash with soap before feeding and after changing diapers
Mixture	Dilute with water not lower than 70 °C, observe the shelf life
Care items	Wash and sterilize regularly
Vaccination	Follow the calendar and start rotavirus vaccination at 6 weeks
[48]

Frequently asked questions from parents

How can you tell if your child is becoming dehydrated?
Wet diapers become less frequent, mucus becomes dry, the child is lethargic, cries without tears, and the skin and fontanelle appear sunken. This is a sign to immediately begin oral rehydration and consult a doctor. [49]

Can water be given instead of over-the-counter rehydration solution?
No. Water doesn't contain the required proportion of salts and sugar, so it doesn't eliminate the electrolyte deficiency and can worsen the condition. A specialized rehydration solution is needed. [50]

Should I dilute the formula or switch to lactose-free formula?
No, this is usually not necessary. Keep the regular formula at its usual concentration. Exceptions are made by the doctor in cases of proven intolerance. [51]

Is zinc beneficial for very young children?
Yes, for children under 6 months, the recommended dose is 10 mg per day for 10-14 days, as discussed with a doctor. This shortens the duration of the episode. [52]

Are probiotics dangerous?
In some older children, they shorten the duration of diarrhea, but in newborns and premature babies, rare but dangerous complications are possible, so the decision is made by a doctor. [53]

When is it urgent to go to the hospital?
If the child is under 3 months old and has a temperature of 38.0°C or higher, if there is lethargy, refusal to drink or breastfeed, blood in the stool, green vomit, signs of dehydration or shock. [54]