Systemic infections with Hemophilus influenzae are commonly seen in infants over 2 months of age and young children, but are rare in the neonate. Fothergill and Wright1 demonstrated that the blood of adults, older children, and newborn infants is usually bactericidal for H influenzae. These investigators also showed that the blood of infants over 2 months of age and young children lacks this property. They concluded that protection is acquired through infection in childhood, and that mothers transmit a temporary immunity to their newborn infants.
Mathies et al2 described a case of H influenzae meningitis in a premature infant and reported that the serum of the infant's mother was not bactericidal for H influenzae. Collier et all studied the maternal blood of two neonates with H influenzae meningitis and found that these mothers also lacked protective activity against H influenzae. Further examination later revealed adequate bactericidal activity.
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