Pediatric blood cultures.

The clinical and laboratory issues important in pediatric blood cultures are similar to those in adult blood cultures with a few noteworthy exceptions. The collection of an uncontaminated specimen and an ample volume of blood is more difficult, especially in neonates. In addition, children often have previously received oral antibiotics or a broad-spectrum parenteral antibiotic. The relative frequencies of the pathogens causing bacteremia in children are different in important ways from in adults. Haemophilus influenzae b, although much less common than in the past, is still an important pediatric pathogen. Meningococcemia is relatively more common in children than in adults, and enterobacteriaceae and anaerobes are relatively less common. Group B streptococci, E. coli, coagulase-negative staphylococci, and Candida sp. are the principal pathogens in neonates. More changes in the distribution of blood-borne pathogens can be expected in the future with the introduction of new or more effective vaccines against the pneumococcus, meningococcus, and, possibly, group B streptococcus. In suspected community-acquired bacteremia in otherwise normal children, a single aerobic blood culture of adequate volume is sufficient. Sick neonates, hospitalized children with indwelling intravascular devices, and immunocompromised children may need multiple blood cultures, paired cultures from an indwelling vascular catheter and a peripheral vein, or use of special media. There is no single optimal system for pediatric blood cultures. The BACTEC systems have been adopted as a single system in many hospitals serving both children and adults because of the favorable results reported in children and the preference of using a single automated system. To maximize the detection of bacteremia and fungemia, some laboratories may wish to combine a BACTEC system with a second complementary system, such as the Isolator. Anaerobic, mycobacterial, and other special blood culture media should be reserved for selected patients.