Omphalitis

Updated: Jan 02, 2016
  • Author: Patrick G Gallagher, MD; Chief Editor: Ted Rosenkrantz, MD  more...
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Overview

Background

Omphalitis is an infection of the umbilical stump. [1] It typically presents as a superficial cellulitis that can spread to involve the entire abdominal wall and may progress to necrotizing fasciitis, myonecrosis, or systemic disease. Omphalitis is uncommon in industrialized countries; however, it remains a common cause of neonatal mortality in less developed areas. It is predominantly a disease of the neonate, with only a few cases having been reported in adults.

Approximately three fourths of omphalitis cases are polymicrobial in origin. Aerobic bacteria are present in approximately 85% of infections, predominated by Staphylococcus aureus, group A Streptococcus, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. [2, 3] In the past, studies emphasized the importance of gram-positive organisms (eg, S aureus and group A Streptococcus) in the etiology of omphalitis. This was followed by a series of reports that highlighted the role of gram-negative organisms in the etiology of omphalitis. These studies suggested that the change in etiology may have been caused by the introduction of prophylactic umbilical cord care using antistaphylococcal agents, such as hexachlorophene and triple dye (a widely adopted practice in the 1960s), with a subsequent increase in gram-negative colonization of the umbilical stump.

In addition to monitoring trends in incidence, monitoring the microbial etiology of omphalitis is important, as recent trends have moved back to dry cord care, without routine application of topical antiseptic agents. This trend has been widely accepted, including by the American Academy of Pediatrics (AAP). [4] Similarly, the World Health Organization (WHO) currently recommends dry cord care, primarily because there have not been strong studies supporting routine application of topical antiseptic agents. [5, 6] These recommendations for dry cord care in developed countries are supported by large, systematic reviews. [5, 7] The exception in developed countries may be after home delivery, where topical application of an antiseptic agent to the umbilical cord may be indicated. [8, 9]

Dry cord care leads to earlier separation of the cord after birth. It also leads to reports of wetter, odoriferous cords (described by some parents as nasty, smelly, or yucky) and higher colonization rates with S aureus and other bacteria (sometimes dramatically so). Whether this increased colonization rate is, or will be, associated with higher rates of omphalitis or other neonatal infection is controversial. Some studies have suggested that higher colonization rates are associated with increased infection, whereas others have not.

Dry cord care may not be appropriate in certain populations. Because there is increased risk of omphalitis and other serious neonatal infections when delivery occurs in a nonhygienic environment, application of a topic antiseptic agent to the cord may be indicated. The WHO recommends topical application of chlorhexidine to the umbilical cord stump during the first week of life for neonates born at home in high neonatal mortality settings (ie, those with at least 30 neonatal deaths per 1000 live births). [6] Meta-analysis of topical application of chlorhexidine to the umbilical cord of children born in underdeveloped countries under nonhygenic conditions revealed that this intervention significantly reduced the incidence of omphalitis, as well as overall neonatal mortality. Optimal dosing strategies for chlorhexidine application are unknown. [8]

A Cochrane review of 12 trials showed that information regarding the effects of chlorhexidine applied to the umbilical cords of newborns in hospital settings on neonatal mortality is not clear. [10] Two trials had moderate-quality evidence that chlorhexidine cord cleansing reduced the risk of omphalitis/infections compared with dry cord care. Another two trials had low-quality evidence that no difference exists for omphalitis/infections between groups receiving chlorhexidine skin cleansing and dry cord care. However, there was high-quality evidence that chlorhexidine skin or cord care in the community setting led to a 50% reduction in the incidence of omphalitis and a 12% reduction in neonatal mortality. [10]  No difference was noted for neonatal mortality or the risk of infections in hospital settings for maternal vaginal chlorhexidine use compared to usual care.

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Pathophysiology

The umbilical cord connects the fetus to the mother in utero. Composed of connective tissue and blood vessels, the cord is cut immediately after birth, leaving the umbilical stump. Normally, the cord area is colonized with potential bacterial pathogens during or soon after birth. These bacteria attract polymorphonuclear leukocytes to the umbilical cord. Although the precise mechanisms of umbilical cord separation are unknown, granulocyte influx and phagocytosis, as well as desiccation, tissue infarction and necrosis, and the activity of collagenase and other proteases, all contribute to the process.

The umbilical stump represents a unique, but universally acquired, wound that, as the tissue undergoes devitalization, provides a medium that supports the growth of bacteria. These bacteria have the potential to invade the umbilical stump, leading to omphalitis. If this occurs, the infection may progress beyond the subcutaneous tissues to involve fascial planes (necrotizing fasciitis), abdominal wall musculature(myonecrosis), and, when the bacteria invade the umbilical vessels, the umbilical and portal veins (phlebitis). The factors that cause colonization to progress to infection are not well understood. The image below shows the anatomic relationship between the umbilicus and its embryologic attachments.

Anatomic relationship between the umbilicus and it Anatomic relationship between the umbilicus and its embryologic attachments.
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Epidemiology

International

Overall incidence varies from 0.2-0.7% in industrialized countries. [11] Incidence is higher in hospitalized preterm infants than in full-term infants. Episodes of omphalitis are reported and are usually sporadic, but, rarely, epidemics occur (eg, due to S aureus or group A Streptococcus). [12, 13, 14]

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Mortality/Morbidity

The prognosis for infants with omphalitis varies.

Outcome is usually favorable in infants with uncomplicated omphalitis associated with cellulitis of the anterior abdominal wall. In a study by Sawin and colleagues, no deaths occurred among 32 infants with omphalitis in the absence of necrotizing fasciitis and myonecrosis. [15] The mortality rate among all infants with omphalitis, including those who develop complications, is estimated at 7-15%. The mortality rate is significantly higher (38-87%) after the development of necrotizing fasciitis or myonecrosis. Suggested risk factors for poor prognosis include male sex, prematurity or being small for gestational age, and septic delivery (including unplanned home delivery); however, data are limited and conclusions cannot be drawn regarding the role of these factors in the mortality rate.

Complications

The sequelae of omphalitis may be associated with significant morbidity and mortality. These include necrotizing fasciitis; myonecrosis; sepsis; septic embolization; and, particularly, endocarditis and liver abscess formation, abdominal complications (eg, spontaneous evisceration, peritonitis, bowel obstruction, abdominal or retroperitoneal abscess), and death. [16, 17, 18]

Necrotizing fasciitis

This is a florid bacterial infection of the skin, subcutaneous fat, and superficial and deep fascia that complicates 8-16% of cases of neonatal omphalitis. [19, 20, 21, 22, 23, 24, 25] It is characterized by rapidly spreading infection and severe systemic toxicity. Necrotizing fasciitis typically involves the abdominal wall but may also involve the scrotum or penis.

Necrotizing soft-tissue infections are caused by production of factors (by single or multiple organisms) that lead directly to tissue cell death, enzymatic destruction of supporting connective tissue, and destruction of host humoral and cellular immune responses to infecting organisms.

Certain organisms are well known to invade tissue and proliferate in necrotic areas. Group A Streptococcus, S aureus, and Clostridium species may elaborate extracellular enzymes and toxins that can damage tissue, may facilitate movement of organisms through soft-tissue planes, and may limit host defenses and penetration of systemic antimicrobial agents. [3]

Myonecrosis

This refers to infectious involvement of muscle.

In infants with omphalitis, development of myonecrosis usually depends on conditions that facilitate the growth of anaerobic organisms. These conditions include the presence of necrotic tissue, poor blood supply, foreign material, and established infection by aerobic bacteria such as staphylococci or streptococci. C perfringens, in particular, does not replicate under conditions of an oxidation-reduction potential (Eh) greater than -80 mV; the Eh of healthy muscle is 120-160 mV. In infections with mixtures of facultative aerobes and anaerobes, the aerobic organisms use oxygen available in tissue, thereby further reducing the Eh in tissues inoculated by Clostridium species or other anaerobic bacteria, often to less than -150 mV, allowing anaerobic bacterial growth.

The toxins produced in the anaerobic environment of necrotic tissue allow rapid spread of organisms through tissue planes. Local spread of toxins extends the area of tissue necrosis, allowing continued growth of organisms and increasing elaboration of toxins. Because of progressive deep tissue destruction and subsequent systemic spread of toxins, anaerobic infections, in particular, may be fatal if not treated promptly. In addition, rapid development of edema, which constricts the muscle within its fascia, may lead to ischemic myonecrosis.

Sepsis

This is the most common complication of omphalitis. In a study by Mason and colleagues, bacteremia was a complication in 13% of infants with omphalitis. In these infants, disseminated intravascular coagulation (DIC) and multiple organ failure may occur. [26]

Septic embolization

If septic embolization arises from infected umbilical vessels, it may lead to metastatic foci in various organs, including the heart, liver, lungs, pancreas, kidneys, and skin.

Abdominal complications

Abdominal complications include spontaneous evisceration, peritonitis, bowel obstruction, abdominal abscess, retroperitoneal abscess, or liver abscess.

Long-term or late complications of omphalitis

These may include nonneoplastic cavernous transformation of the portal vein, portal vein thrombosis, extrahepatic portal hypertension, and biliary obstruction. [27, 28, 29]

Sex

No sex predilection has been reported, although males may have a worse prognosis than females.

Age

In full-term infants, the mean age at onset is 5-9 days. In preterm infants, the mean age at onset is 3-5 days.

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