Alec A. Rudentein, MS3 Rowan SOM; Raveena K. Midha, MS3 Rowan SOM; Puthenmadam Radhakrishnan MD, MPH, FAAP

INTRODUCTION

Salmonella gastroenteritis is an infection that can result in serious and life-threatening complications in the pediatric population. Infants below the age of 12 months are especially at an increased risk of morbidity and mortality. Our case is a 4-month-old male who presents with gastroenteritis in the ED and evaluated for sepsis. Stool cultures were taken and resulted in a positive salmonella gastroenteritis diagnosis. Gastroenteritis
is a common presentation in infants and is often not infectious in etiology.We present this case because it is imperative to acknowledge that salmonella infection is a potential and serious cause of gastroenteritis in infants. A search of literature resulted in many mentions of statistics and epidemiology; there are very scant case reports on Salmonella infections in infants.

CASE DESCRIPTION

This is a case of a 4-month-old male with no significant past medical history, born at full term who presented to the emergency department with reports of a fever and loose stools. Patient’s mother reported that onset of symptoms was 6 hours prior to presentation and temperature at home was 102.2 F.The patient had no sick contacts; no recent travel, no pets at home and all immunizations were up to date. Initial VS were significant for a rectal temperature of 105.9 and a HR of 200 BPM. Physical exam showed yellowish stools with streaks of blood, all other findings were unremarkable. Laboratory findings were significant for an elevated absolute neutrophil count (7.38×10^3/mcl), an elevated absolute lymphocyte count (0.72 x 10^3/mcl), and an elevated CRP (2.0 mg/dL). Urinalysis was normal and the patient was negative for influenza, COVID-19, and RSV. XR of chest/ abdomen showed no acute abnormalities. Patient was admitted to the pediatric in-patient floor for further evaluation and a stool culture was ordered.

On the pediatric floor, the patient was given acetaminophen and IV fluid for hydration. A sepsis evaluation including lumbar puncture with CSF cultures and blood cultures were performed on hospital day 2. Stool culture obtained were positive for Salmonella species. After a discussion with pediatric ID, it was decided that the patient would be placed on IV ceftriaxone. The patient’s diarrhea began decreasing on hospital day 5 and stools remained non-bloody for more than 24 hours. Blood culture and CSF cultures showed no growth after 2 days. Patient’s intake increased to 4 oz of fullstrength formula every 4 hrs. After the patient was afebrile for approximately 36 hours, he was discharged on hospital day 6 and placed on azithromycin PO for a duration of 5 days.

DISCUSSION

Salmonella is a motile, gram-negative facultative anaerobic bacilli as part of the Enterobacteriaceae family.There are numerous Salmonella serotypes and species; however, this case focuses on non-typhoidal Salmonella species and their particular deleterious effects in infants. Most non-typhoidal Salmonella infections are acquired through food-borne contaminants. Frequent transmission of non-typhoid Salmonella infections occurs due to the consumption of contaminated animal-based food, such as eggs, meat, dairy products, contaminated water, or poor hygiene [3]. The infections can be self-limiting or progress to more advanced states. In addition, formula is also a potential nidus for Salmonella infection. The improper storage of formula is the most likely cause of formula-caused Salmonella infection [3]. Furthermore, Salmonella, unlike many other enteric pathogens, have an asymptomatic carrier state which can help spread the disease. A common way for the pathogen to spread to newborns and children is through maternal asymptomatic carriers [1,3].

In the case presented, it was thought that the patient was exposed to Salmonella via mishandling of poultry or an asymptomatic carrier.As there was no local outbreak of Salmonella from the formula, the Department of Health decided not to pursue the formula avenue. Likewise, the patient had no recent travel, no sick contacts and no pets at home.The patient’s mother cooks meals for the family so it can be speculated that the pathogen spread from the food to the mother to the patient.

Salmonella causes its effects locally within the gastrointestinal site as well as distantly through its ability to invade the intestinal mucosa and replicate within the lamina propria. From there, it can invade the mesenteric lymph nodes and spread to the rest
of the body. Salmonella gastroenteritis is commonly associated with diarrhea, first starting with watery diarrhea and possibly progressing to bloody or mucus-containing diarrhea due to its invasive properties [1,3]. In immunocompetent adults, Salmonella gastroenteritis is eliminated through the body’s immune response, the naturally occurring enteric flora, gastric acid, and motility, as well as the intestinal mucus. Each aspect works to remove the pathogen as well as form protective barriers to prevent the organism from acclimating to the host’s internal environment. Infants and children lack or have an immature defense system and are thus at increased risk of developing more serious complications of Salmonella infections [1,4].

Noting Salmonella as the cause of gastroenteritis is imperative due to the systemic effects the organism can have. “Bacteremia may occur in 30-50% of neonates infected with Salmonella, including those with no evidence of gastroenteritis. Focal infections of almost every organ system (for example bone, joint, lung) are reported with Salmonella gastroenteritis, but meningitis is the most feared of these complications and emphasizes the vigilance required to evaluate infants who are infected with Salmonella” [1].The peak incidence of Salmonella bacteremia and meningitis occur in infants less than 2 months of age [2]. According to the CDC, infants, especially those who are not breastfed or have a weakened immune system, are more likely to get an invasive Salmonella infection and should be treated with antibiotics [3,4].

It is recommended that the use of antibiotics be limited in immunocompetent individuals aged 12 months to 50 years old with acute salmonella gastroenteritis because of the self-limiting course of disease. It is established that patient’s less than 3 months of age are given antibiotics due to a risk of complications such as sepsis and meningitis [9]. However, there is little evidence to support that antibiotics should be given from 3 months to 12 months of age. According to a review of literature in 2017, the current recommended guidelines for a patient between 3 months-12 months of age is no treatment required if the patient appears well and non-toxic. If the patient is unwell or toxic appearing, then blood culture, with or without CSF culture, should be obtained and parenteral antibiotics should be started. If the blood culture shows no growth at 48 hours and the patient appears well, then the patient can be switched to oral antibiotics [6]. Antibiotic therapy duration for immunocompetent children is recommended at 3-14 days [5]. According to these guidelines, it was necessary to place our patient on antibiotic therapy due to multiple bouts of bloody diarrhea and persistently high fever, dehydration and general ill appearance.

The mainstay treatment of Salmonella gastroenteritis for adults and adolescents is an oral dose of fluoroquinolones because of their antimicrobial activity against gram-negative enteric pathogens. Some data has shown that fluoroquinolones could potentially be safe during short courses of antibiotics for children. However, previous data on animal models suggests that fluoroquinolones can cause joint toxicity and cartilage damage.
As a result, they are not typically prescribed in children [8]. Alternatives to fluoroquinolones are other oral antibiotics such as TMP-SMX, cefixime and azithromycin. Due to this patient’s poor oral intake and peripheral IV access, IV ceftriaxone was a reasonable choice of antimicrobial therapy. Ceftriaxone has been shown to be as effective as oral ciprofloxacin in children with acute invasive diarrheas [ 7]. In addition, ceftriaxone eliminates the risk of joint toxicity in vulnerable pediatric patients such as this 4-month-old male. In this case, the duration of parenteral antibiotic therapy was 3 days. Following discharge, the patient was prescribed azithromycin for 5 additional days for a total of 7 days which falls in the recommended guidelines discussed above.

CONCLUSION

Gastroenteritis in infants, particularly children under 12 months of age, is a common condition with a range of causes. In many cases, the illness is self-limited and no antibiotics or treatments are needed. However, it is important to note that Salmonella is also a common cause of gastroenteritis and should always be included in the differential diagnosis. In the case presented, the patient was brought to the ED for a sepsis workup and it was most likely due to the presentation of bloody stools that the stool culture was ordered. However, Salmonella’s presentation can vary from watery stools to asymptomatic infections.Though the clinical presentations differ, Salmonella’s potential systematic effects can prove to be fatal. Therefore, Salmonella gastroenteritis should be considered in the differential diagnosis due to its ability to invade the lymphatic system and spread to cause more systemic infections.

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