Omphalitis

Etiology

Immediately after birth, the umbilicus becomes colonized with many different types of bacteria. Gram-positive cocci are present within hours, followed shortly by many enteric microorganisms. The devitalized tissues of the umbilical stump promote the rapid growth of these bacteria, and the thrombosed blood vessels allow entry into the bloodstream, potentially leading to systemic infection.

Epidemiology

Omphalitis is uncommon beyond the neonatal age. Symptoms typically begin at an average age of 3 days. This is a rare disease in developed countries, with an incidence of 0.7%. However, in developing countries, the incidence of neonates delivered at hospitals can approach 8%, and if born at home, the incidence can be as high as 22%.[2][3] Risk factors for the development of omphalitis include low birth weight, prolonged rupture of membranes, maternal infection, umbilical catheterization, nonsterile delivery, maternal infection, prolonged labor, home birth, and improper cord care.

The cultural application of cow dung, seen in developing nations, is also associated with higher rates of omphalitis. In addition, immune system abnormalities such as defective leukocyte adhesion, poor neutrophil mobility, low natural killer function, and interferon production have been associated with an increased risk of omphalitis.[4] A history of delayed separation of the umbilical cord stump and omphalitis after birth age with recurrent infections in infancy should raise the suspicion of leukocyte adhesion disorder (LAD) and an appropriate workup must be done. Apart from omphalitis, children with LAD commonly have recurrent pneumonia, soft tissue infections, and gingivitis.

Pathophysiology

The umbilical cord is the lifeline between the baby and mother during pregnancy and is cut after birth. The umbilical cord stump then gradually dries and typically falls off within 5 to 15 days. Skin and enteric bacteria may colonize the devitalized tissue of the stump and lead to infection. Omphalitis is, therefore, a polymicrobial infection, and the most common pathogens are Staphylococcus aureus, Streptococcus pyogenes, and gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis.[5] If maternal infection with chorioamnionitis is suspected, anaerobic bacteria such as Bacteroides fragilis, Clostridium perfringens, and Clostridium tetani can also contribute to infection.[6]

History and Physical

Omphalitis is primarily a neonate disease characterized by tenderness, erythema, and induration of the umbilicus and surrounding tissues. Early on, patients may only have superficial cellulitis, but if untreated, this can involve the entire abdominal wall. Patients may also have purulent drainage or bleeding from the umbilical cord stump. Foul-smelling discharge should raise the suspicion of anaerobic infection. Systemic symptoms such as lethargy, poor feeding, fever, and irritability suggest sepsis and portend a worse prognosis. If there is a rapid progression of abdominal wall erythema or gas in the surrounding tissues, necrotizing fasciitis should be considered, and acute surgical consultation is needed.[7]

Evaluation

Laboratory evaluation with complete blood count and culture should be obtained for all patients with suspected omphalitis. In addition, if possible, cultures of any purulent material from the umbilical stump should be sent before the initiation of antibiotics. A full neonatal septic workup should be obtained if the patient has systemic symptoms, including a chest radiograph, urinalysis, urine culture, and cerebrospinal fluid culture. As omphalitis is closely linked to leucocyte adhesion disorders, a detailed workup is necessary in suspected cases. Leucocytosis, due to defective margination of leucocytes, is almost always present in LAD. Leukocyte adhesion molecules or integrins, including LFA-1/Mac-1, p150, and p95, are absent in children with LAD. Therefore, an assay of these receptors is essential in children presenting with recurrent infections and having a history of omphalitis in the neonatal age.[8]

Treatment / Management

Broad-spectrum parenteral antibiotics are required to treat omphalitis. Antibiotic coverage should be directed against both gram-positive and gram-negative organisms. Initial empiric treatment with antistaphylococcal penicillin and aminoglycoside is recommended. If there is a high prevalence of methicillin-resistant Staphylococcus aureus, vancomycin should be administered while awaiting culture results. If there is suspicion of maternal chorioamnionitis or the patient has a foul-smelling discharge from the stump, clindamycin or metronidazole is indicated to cover for anaerobes.[6] The duration of antibiotic therapy depends on the patient's clinical response and any complications that may develop during hospital admission. For uncomplicated cases of omphalitis, the recommended course of parenteral therapy is ten days, followed by a switch to oral therapy, depending on culture results.

Differential Diagnosis

In most cases, the clinical picture of omphalitis is sufficient to make the diagnosis. A patent urachus, which results in direct communication between the bladder and umbilicus, can be mistaken for infection due to persistent drainage from the umbilicus. Umbilical granulomas may also be misdiagnosed as an umbilical infection because the friable tissue can cause serous or serosanguinous drainage and easy bleeding with trauma. These typically occur after the first week of life and can be distinguished by their soft, velvety texture and pinkish color. Umbilical polyps are firm masses of urachal embryologic remnants that often require surgical excision but do not cause infection.[9] If inflammation of the umbilical cord alone is present, then funisitis and not omphalitis is the diagnosis. Funisitis, caused by maternal chorioamnionitis, involves only the external surface of the cord and not the umbilical vessels. A wet, foul-smelling cord stump without any surrounding cellulitis characterizes funisitis.

Complications

Early recognition and treatment of omphalitis are essential to prevent the serious complications of this disease. Sepsis is the most common complication and can progress to septic shock and death. Other rare complications include peritonitis, intestinal gangrene, small bowel evisceration, liver abscess, septic umbilical arteritis, and portal vein thrombosis. Although uncommon, necrotizing fasciitis can occur and should be suspected if there is a rapid progression of infection and signs of systemic toxicity; it should also be suspected if there is no clinical improvement with intravenous antibiotics in 24 to 48 hours. Mortality rates as high as 60% to 85% have been reported in patients with omphalitis complicated by necrotizing fasciitis.[10] If suspected, in addition to the broad-spectrum antibiotics, prompt surgical consultation for debridement of the umbilical structures and the involved abdominal wall is essential.