Use of the Becton-Dickinson urine culture tube with the Abbott MS-2 urine screening system

Urine specimens were obtained from 312 obstetric outpatients by sterile midstream technique and aliquots placed in both Becton-Dickinson urine culture tubes and sterile conventional tubes. Quantitative cultures were made from each tube, and each tube was screened for bacteria with the Abbott MS-2 urine screening system. The time required to detect bacteriuria was recorded for both specimens. Isolates from specimens containing ≥50,000/ml gram-positive cocci or ≥100,000/ml gram-negative bacilli were identified and antimicrobial susceptibility tests performed. Delayed (24 hr) quantitative cultures were done from Becton-Dickinson tubes. By these criteria, 124 urine specimens were positive in both conventional and Becton-Dickinson tubes. Escherichia coli (n = 72, Klebsiella pneumoniae (n = 20), Enterobacter cloacae (n = 8), Proteus mirabilis (n = 4), group B streptococcus (n = 12), and enterococcus (n = 8) were isolated. Time for detection of positive urine samples was similar in both types of tubes. Delayed cultures had significant numbers of false-positive results. Antimicrobial susceptibility results did not appear to be influenced greatly by Becton-Dickinson tube transport. The MS-2 cannot adequatey discriminate cultures containing <50,000 colony-forming units/ml of urine. The Becton-Dickinson tube appears to be compatible for use with the MS-2 for purposes of screening for bacteriuria.