title: Bactericidal activity against coagulase-negative staphylococci is impaired in infants receiving long-term parenteral nutrition.
abstract: OBJECTIVE
  To examine the role of total parenteral nutrition (TPN) in predisposing infants to infection caused by coagulase-negative staphylococci.
  
  
  BACKGROUND
  Total parenteral nutrition is an important means of providing essential nutrients to newborn infants. However, its use has been associated with complications, particularly infection caused by coagulase-negative staphylococci. Recent data suggest that TPN may modulate immune function; however, reports directly indicating impaired immunity against coagulase-negative staphylococci during TPN are limited.
  
  
  METHODS
  Study 1 involved 31 infants younger than 4 months who had undergone surgery and were not receiving antibiotics; 20 were receiving TPN and 11 were receiving a normal enteral diet. An in vitro whole blood model was used to measure the host bactericidal activity against coagulase-negative staphylococci. Bacterial killing and phagocytosis were measured after a 45-minute challenge with viable coagulase-negative staphylococci. In study 2, whole blood killing and intracellular killing of coagulase-negative staphylococci were measured in five newborn infants (younger than 2 months) who were receiving long-term TPN (>10 days), five control infants receiving a normal enteral diet, and five healthy adults.
  
  
  RESULTS
  In study 1, infants receiving a normal enteral diet showed a high capacity to ingest and kill coagulase-negative staphylococci. In contrast, the blood of infants receiving long-term TPN showed a reduction in coagulase-negative staphylococci phagocytosis and killing. There were significant negative linear correlations between the duration of TPN and killing of coagulase-negative staphylococci and phagocytosis of coagulase-negative staphylococci. In study 2, infants receiving long-term TPN had lower whole blood killing and intracellular killing than infants receiving a normal enteral diet and healthy adult volunteers. These data seem to indicate a neutrophil dysfunction mediated by TPN in infancy.
  
  
  CONCLUSIONS
  Host defense mechanisms, including phagocytosis and killing of coagulase-negative staphylococci, are impaired during long-term TPN. The impaired bactericidal activity seems to be related to defective intracellular killing in neutrophils. These findings may explain the high rate of septicemia caused by coagulase-negative staphylococci in infants receiving TPN.
authors.affiliation: Institute of Child Health and Great Ormond Street Hospital for Children NHS Trust, University College London, United Kingdom.
authors.forename: Y
authors.initials: Y
authors.lastname: Okada
authors.forename: N J
authors.initials: NJ
authors.lastname: Klein
authors.forename: H K
authors.initials: HK
authors.lastname: van Saene
authors.forename: G
authors.initials: G
authors.lastname: Webb
authors.forename: H
authors.initials: H
authors.lastname: Holzel
authors.forename: A
authors.initials: A
authors.lastname: Pierro
mesh_terms: D000328:Adult; D016470:Bacteremia / Q000276:immunology; D001770:Blood Bactericidal Activity; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007231:Infant, Newborn; D009504:Neutrophils / Q000276:immunology; D010289:Parenteral Nutrition, Total / Q000009:adverse effects*; D010587:Phagocytosis; D013203:Staphylococcal Infections / Q000276:immunology; D013210:Staphylococcus / Q000276:immunology*