Neonatal necrotising enterocolitis

An update on the human and animal enteric pathogen Clostridium perfringens

Clostridium perfringens, a rapid-growing pathogen known to secrete an arsenal of >20 virulent toxins, has been associated with intestinal diseases in both animals and humans throughout the past century. Recent advances in genomic analysis and experimental systems make it timely to re-visit this clinically and veterinary important pathogen. This Review will summarise our understanding of the genomics and virulence-linked factors, including antimicrobial potentials and secreted toxins of this gut pathogen, and then its up-to-date clinical epidemiology and biological role in the pathogenesis of several important human and animal-associated intestinal diseases, including pre-term necrotising enterocolitis. Finally, we highlight some of the important unresolved questions in relation to C. perfringens-mediated infections, and implications for future research directions.

Massive pneumatosis without necrosis: A case report of Clostridium perfringens sepsis in an extremely low birth weight infant

Pneumatosis intestinalis and free intraperitoneal air on abdominal radiographs are considered pathognomonic signs of necrotizing enterocolitis (NEC). We report a unique case of late-onset fulminant sepsis due to Clostridium perfringens presenting with shock, extensive pneumatosis intestinalis and free intraperitoneal air in an extremely low birth weight infant without histopathological evidence of bowel necrosis or NEC.

Cocaine exposure in a term neonate. Necrotizing enterocolitis as a complication

Cocaine use has increased dramatically in the past several years, and multiple medical complications associated with its use have been reported in adults, including bowel infarction and colitis. Maternal use of cocaine during pregnancy has been associated with complications in the fetus and newborn infant, including spontaneous abortions, preterm labor, cerebral infarctions, seizures, renal anomalies, and neurobehavioral and neurophysiologic abnormalities. This paper presents a case of necrotizing enterocolitis at birth in a term newborn exposed to cocaine antenatally. Cultures of the bowel grew two types of Clostridia organisms, Escherichia coli and group B streptococcus. It is suggested that bowel ischemia was secondary to the vasoconstrictive properties of the maternally abused cocaine and that secondary invasion of the bowel by multiple bacteria ensued. This case presents another possible complication to the newborn of maternal cocaine exposure in utero, namely ischemic infarction of the bowel.

Bifidobacterium, Bacteroides, and Clostridium spp. in fecal samples from breast-fed and bottle-fed infants with and without iron supplement

Bifidobacterium, Bacteroides, and Clostridium spp. isolated from the feces of 23 neonates during the first 3 months of life were identified. Of the 23 neonates, 10 were breast fed, 6 received an infant formula with iron supplement (5 mg/liter), and 7 received the formula without iron supplement (iron concentration, less than 0.5 mg/liter). The Bifidobacterium spp. most frequently isolated from the three groups of infants were B. longum, B. breve, B. adolescentis, and B. bifidum. The bacteroides spp. most frequently isolated were B. fragilis and B. vulgatus. The most common Clostridium sp. in the three groups of infants was C. perfringens. The type of milk did not select for species of Bifidobacterium, Bacteroides, or Clostridium, except for Clostridium butyricum, which was isolated significantly more often from bottle-fed infants with iron supplement than from the other groups, and Clostridium tertium, which was more often isolated from breast-fed infants. The species of the three anaerobic genera did not persist for a long period of time in the three groups of infants.

Clostridial necrotizing enterocolitis

In a bacteriologic investigation of infants with necrotizing enterocolitis (NEC), 16 of 50 infants had clostridia in cultures of blood or of peritoneal fluid obtained by paracentesis. Twenty-eight of the 50 infants had enteric bacteria other than clostridia, and six infants had sterile cultures. Of the 16 infants with clostridia, nine had C. perfringens and seven had other species of clostridia. Compared to infants with nonclostridial NEC, those with clostridial NEC were larger and more mature, had more extensive pneumatosis intestinalis and gangrene and more rapid progression of NEC. The nine infants with C. perfringens had a fulminant form of NEC, analogous to gas-gangrene of the intestine. Mortality in this group was 78% (7/9). The seven infants with clostridial species other than C. perfringens had a mortality comparable to that of infants with nonclostridial NEC (32%). Improved survival from NEC associated with C. perfringens may be possible only by prevention, rather than earlier diagnosis and improved heroic treatment.

Quantitative study of the aerobic and anaerobic faecal flora in neonatal necrotising enterocolitis

Faeces from 24 neonates with proved necrotising enterocolitis (NEC), from 12 with clinically suspected NEC, and from 41 control infants were quantitatively cultured under aerobic and anaerobic conditions. An important difference in colonisation with Klebsiella was found between the NEC groups and the control group. Although the cause of NEC is unknown, colonisation with Klebsiella seems to increase the risk.

The prevalence of Clostridium difficile and toxin in a nursery population: a comparison between patients with necrotizing enterocolitis and an asymptomatic group

During a period when certain neonates in our nursery developed necrotizing enterocolitis, we studied stool specimens from a population of symptomatic and asymptomatic patients for the presence of Clostridium difficile and its toxin. The presence of the organism among nursery personnel and in the nursery environment was also evaluated. Results showed that five symptomatic neonates and 17 asymptomatic neonates in a population of 37 patients studied in our neonatal intensive care and intermediate care nurseries had positive stool cultures for C. difficile. Toxin was detected in stool from four of five symptomatic patients and was present at dilutions of greater than 1/125 in stool from six asymptomatic patients who were culture positive for C difficile. The organism was not found in stool samples from any nursery personnel but was recovered from the hand culture of a nursery worker and from the inanimate environment. Although our findings support the notion of nosocomial spread of C difficile, we were unable to clearly implicate the organism as the cause of necrotizing enterocolitis in our nursery.

Clostridia isolated from the feces of infants during the first year of life

Clostridia isolated from the feces of ten healthy infants during the first year of life were identified. All infants excreted clostridia during the first week of life; the most common species were Clostridium butyricum, C. paraputrificum, and C. difficile. In the formula-fed infants colonization occurred consistently throughout the year, whereas in some breast-fed infants it was inhibited until weaning. The species isolated most frequently throughout the year were C. paraputrificum, C. butyricum, C. ramosum, C. sartagoformum, and C. perfringens. Of the species often found in infants, C. butyricum, C. difficile, and C. sartagoformum occur rarely in adults, reflecting differences in the environmental conditions in the gut of the two age groups. The mechanism by which environmental conditions select species of clostridia is unknown but may be important to our understanding of a variety of clostridial intestinal infections. It was demonstrated that species of clostridia which have been implicated in the etiology of neonatal necrotizing enterocolitis form part of the normal infant gastrointestinal microflora.

A bacteriologic basis for the clinical presentations of necrotizing enterocolitis

A study to identify putative bacterial pathogens in infants with necrotizing enterocolitis (NEC) was begun in 1976. Cultures of blood and of peritoneal fluid obtained by paracentesis were carried out in 25 infants with NEC. Segments of intestine excised at operation were Gram stained. Of the 25 infants, 8 recovered with medical management and 17 required operations. The 8 medically treated infants had sterile peritoneal fluid and, with 2 exceptions, sterile blood cultures. Of the 17 operated infants, 16 had bacteria in their blood and/or peritoneal fluid. The majority of resected bowel specimens from these infants contained a confirmatory morphologic type of bacterium within the wall. The clinical course of 8 infants with clostridia was compared to that of 8 infants with gram-negative enteric bacteria (Klebsiella, E. coli, or Bacteroides fragilis). The infants with clostridia were sicker. They had more extensive pneumatosis intestinalis, a higher incidence of portal venous gas, more rapid progression to gangrene, and more extensive gangrene. Infants with gram-negative rods had lower birth weights and lower platelet counts than the clostridial group. The difference in mortality between the two groups was not significant. The inherent pathogenicity of the gut flora may influence the clinical course of NEC. Among infants who develop intestinal gangrene, the clostridia appear to be more virulent than gram-negative enteric bacteria.

Neonatal necrotizing enterocolitis: implications for an infectious disease

There is a broad spectrum of presentations and severity of necrotizing enterocolitis. Because it may have several different causes, ncerotizing enterocolitis may be a syndrome rather than a specific disease. The triad of formula feeding, intestinal ischemia, and bacterial growth may be part of the pathogenesis of necrotizing enterocolitis. Bacteria are of central importance for the production of pneumatosis, a prerequisite of which is formula feeding. Bacteria may also contribute to the intestinal injury seen after ischemia. However, the disease in the low risk patient seen during an epidemic associated with a single organism is probably caused by a primary gastrointestinal infection. On the other hand, in the stressed newborn infant with mucosal injury the presence of the appropriate bacteria may be all that is needed to initiate the chain of events leading to necrotizing enterocolitis. Figure 2 illustrates the importance of bacteria in all the causes proposed to be involved in the pathogenesis of necrotizing enterocolitis. Whether bacteria are primary or secondary agents, necrotizing enterocolitis should always be approached therapeutically as an infectious disease.

Fulminant necrotising enterocolitis associated with Clostridia

5 infants with no growth of bacteria on cultures of blood and peritoneal fluid recovered from necrotising enterocolitis after medical treatment alone. 12 infants with positive cultures required surgery. 5 of these 12, who did not harbour clostridia, had a mild clinical course and all 5 survived segmental bowel resection. The 7 infants who harboured clostridia had a more severe clinical course and 4 died. In 3 of 4 infants with Clostridium perfringens, the necrotising enterocolitis was fulminant, characterised by severe pneumatosis intestinalis, extensive gangrene, early intestinal perforation, and a fatal outcome.