Neonatal immune responses to coagulase-negative staphylococci.
OBJECTIVE
Coagulase-negative staphylococci have emerged as the most common nosocomial pathogen in neonatal intensive care units worldwide. Our understanding of the interactions between coagulase-negative staphylococci and the immune system is incomplete, especially in the newborn. This review summarizes current knowledge on the human immune response to coagulase-negative staphylococci, with particular emphasis on the neonatal innate immune system.


RESULTS
There are very limited data on innate immune responses to coagulase-negative staphylococci in neonates. Levels of serum proteins, including transplacental anti-coagulase-negative staphylococci immunoglobulin and complement, correlate with gestational age, and this relative deficiency in preterm infants contributes to their suboptimal opsonization and impaired bacterial killing of coagulase-negative staphylococci. In adults, coagulase-negative staphylococci elicit significant cytokine responses in vitro, which are probably partly mediated by Toll-like receptors, including Toll-like receptor type 2, but these pathways have not been characterized in the high-risk neonatal population.


CONCLUSIONS
The susceptibility of human preterm neonates to coagulase-negative staphylococci relates partly to the immaturity of the neonatal immune response. Strategies to reduce the burden of coagulase-negative staphylococci infections require a thorough understanding of host-pathogen interactions, particularly the engagement of coagulase-negative staphylococci by the neonatal innate immune system.
Strunk
Tobias
T
School of Paediatrics and Child Health, University of Western Australia, Perth, Australia. tobiasstrunk@yahoo.de
Richmond
Peter
P
Simmer
Karen
K
Currie
Andrew
A
Levy
Ofer
O
Burgner
David
D
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000907:Antibodies, Bacterial / Q000276:immunology; D016470:Bacteremia / Q000276:immunology; D003030:Coagulase / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D007113:Immunity, Innate; D007112:Immunity, Maternally-Acquired; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000276:immunology* / Q000382:microbiology / Q000628:therapy; D010586:Phagocytes / Q000276:immunology; D010587:Phagocytosis; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000276:immunology* / Q000382:microbiology / Q000628:therapy; D013210:Staphylococcus / Q000201:enzymology / Q000276:immunology* / Q000472:pathogenicity
D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D003030:Coagulase; D016207:Cytokines