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Bactericidal activity against coagulase-negative staphylococci is impaired in infants receiving long-term parenteral
Y Okada1, N J Klein, H K van Saene
1Institute of Child Health and Great Ormond Street Hospital for Children NHS Trust, University College London, United Kingdom.
Insights
Total parenteral nutrition (TPN) impairs infant immune defenses against coagulase-negative staphylococci infections. This study found reduced bacterial killing and phagocytosis in infants receiving TPN, suggesting neutrophil dysfunction.
Area of Science:
- Neonatal immunology
- Infectious disease
Background:
- Total parenteral nutrition (TPN) is vital for infant nutrition but linked to coagulase-negative staphylococci infections.
- Limited data exist on TPN's direct impact on immunity against these specific bacteria.
Purpose of the Study:
- To investigate how total parenteral nutrition (TPN) predisposes infants to coagulase-negative staphylococci infections.
- To assess the effect of TPN on host bactericidal activity against these pathogens.
Main Methods:
- Two studies compared infants receiving TPN versus enteral diets, and adults.
- An in vitro whole blood model measured bactericidal activity, phagocytosis, and intracellular killing of coagulase-negative staphylococci.
Main Results:
- Infants on TPN exhibited reduced phagocytosis and killing of coagulase-negative staphylococci compared to controls.
- A negative correlation was observed between TPN duration and immune function.
- TPN appears to mediate neutrophil dysfunction in infants.
Conclusions:
- Long-term TPN impairs host defense mechanisms, specifically neutrophil intracellular killing, against coagulase-negative staphylococci.
- Impaired bactericidal activity during TPN may explain increased rates of septicemia in infants.
Objective:
To examine the role of total parenteral nutrition (TPN) in predisposing infants to infection caused by coagulase-negative staphylococci.
Summary Background Data:
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.