Analysis of the efficacy of urine culture as part of sepsis evaluation in the premature infant.

Abstract

Premature infants have a higher incidence of urinary tract infection (UTI) than full term infants. UTI in premature infants can present with signs of sepsis: poor weight gain; temperature instability; metabolic acidosis; poor feeding; and abdominal distention. The purpose of this study was to determine the usefulness of routine urine culture as part of a sepsis evaluation in the preterm infants. We conducted a retrospective review of all infants with birth weight <1500 g (very low birth weight) who underwent sepsis evaluation at MetroHealth Medical Center between January 1991 and February 1998. All infants from whom urine and blood specimens were collected concomitantly for culture as part of a sepsis evaluation were included. Included were 538 infants. Their mean gestational age was 28.5 +/- 2.7 weeks, and mean birth weight was 1072 +/- 276 g. Blood and urine specimens for culture were taken from 349 infants on admission or in the first 24 h of life (Group A), their mean birth weight was 1147 +/- 244 g, and mean gestational age was 28.9 +/- 2.6 weeks. None of these infants had positive urine cultures; 8 infants (2%) had positive blood cultures. Blood and urine specimens were obtained from 189 infants later between Days 6 and 150 of life (Group B); their mean birth weight was 933 +/- 278 g, and mean gestational age was 27.5 +/- 2.5 weeks. Forty-eight infants (25.3%) in Group B had positive urine cultures, and 79 infants (41.7%) had positive blood cultures. Eighteen infants (38%) with positive urine cultures had positive blood cultures, and 30 infants (62%) had negative blood cultures. There is minimal benefit in obtaining urine cultures from very low birth weight infants as part of a sepsis evaluation in the first 24 h of life. It is important to obtain urine cultures from older infants with signs of sepsis to identify patients with UTI with or without bacteremia.