Low mortality in necrotizing enterocolitis associated with coagulase-negative Staphylococcus infection

Preterm infants with necrotising enterocolitis demonstrate an unbalanced gut microbiota

AIM

This Lebanese study tested the hypothesis that differences would exist in the gut microbiota of preterm infants with and without necrotising enterocolitis (NEC), as reported in Western countries.

METHODS

This study compared 11 infants with NEC and 11 controls, all born at 27-35 weeks, in three neonatal intensive care units between January 2013 and March 2015. Faecal samples were collected at key time points, and microbiota was analysed by culture, quantitative PCR (qPCR) and temperature temporal gel electrophoresis (TTGE).

RESULTS

The cultures revealed that all preterm infants were poorly colonised and harboured no more than seven species. Prior to NEC diagnosis, significant differences were observed by qPCR with a higher colonisation by staphylococci (p = 0.034) and lower colonisations by enterococci (p = 0.039) and lactobacilli (p = 0.048) in the NEC group compared to the healthy controls. Throughout the study, virtually all of the infants were colonised by Enterobacteriaceae at high levels. TTGE analysis revealed no particular clusterisation, showing high interindividual variability.

CONCLUSION

The NEC infants were poorly colonised with no more than seven species, and the controls had a more diversified and balanced gut microbiota. Understanding NEC aetiology better could lead to more effective prophylactic interventions and a reduced incidence.

Empiric antibiotic regimens for neonatal sepsis in Australian and New Zealand neonatal intensive care units

AIM

Neonatal sepsis remains an important cause of morbidity and mortality, and requires prompt empiric treatment. However, only a minority of babies who receive antibiotics for suspected sepsis have an infection. Antimicrobial exposure in infancy has important short- and long-term consequences. There is no consensus regarding empirical antimicrobial regimens.

METHODS

The study included a survey of empiric antimicrobial regimens in all tertiary neonatal intensive care units in Australia and New Zealand in 2013-2014.

RESULTS

All 27 units responded. For early-onset sepsis, all units used a combination of gentamicin with either penicillin or ampicillin. For late-onset sepsis, the frequency of units using empiric vancomycin (41%) versus empiric flucloxacillin (48%) was similar. Gestational age or the presence of a central venous catheter had little influence on using vancomycin instead of flucloxacillin. For late-onset sepsis with meningitis there was marked variation in antimicrobial combinations, with 15 different regimens described. A total of 93% used a cefotaxime-based regimen, either as monotherapy (22%) or combined with a second (22%) or third (48%) agent. For suspected necrotising enterocolitis, 89% used an aminoglycoside, metronidazole and a penicillin. Historical outbreaks of multi-resistant organisms exerted long-term influence over regimen choice.

CONCLUSIONS

There was limited use of broad-spectrum agents such as carbapenems or third-generation cephalosporins. In this region with low methicillin-resistant Staphylococcus aureus prevalence, empiric vancomycin use was common, selected for activity against coagulase-negative staphylococci. Empiric vancomycin is rarely necessary because coagulase-negative staphylococci are often contaminants and sepsis is rarely fulminant, occurring almost exclusively in extremely low birthweight infants. Implementation of appropriate, local antimicrobial policies is crucial to minimise antimicrobial exposure in this vulnerable population and halt the development of antimicrobial resistance.

Staphylococcal enterocolitis: forgotten but not gone?

PURPOSE

Staphylococcus aureus may cause antibiotic-associated diarrhea and enterocolitis, with or without preceding antibiotic use, in immunocompromised adults or infants, or individuals with predisposing conditions, but there is little appreciation of this condition clinically. CLINICAL DISEASE: The main clinical feature that helps to differentiate staphylococcal enterocolitis (SEC) from Clostridium difficile-associated diarrhea is large-volume, cholera-like diarrhea in the former case. A predominance of gram-positive cocci in clusters on gram stain of stool or biopsy specimens and the isolation of S. aureus as the dominant or sole flora support the diagnosis.

PATHOGENESIS

The pathogenesis of SEC requires the interaction of staphylococcal enterotoxins, which function as superantigens, with interstitial epithelial lymphocytes and intestinal epithelial cells (IECs).

MANAGEMENT

Most SEC represents recent S. aureus acquisition, so that improved infection prevention practices can reduce disease recurrence. Management should include aggressive fluid management and repletion and oral vancomycin.