Molecular Typing to Demonstrate Transmission of Gram-Negative Bacteria in the NICU |[dagger]| 1417

Objectives: To study spread of clones of aerobic gram-negative rods (GNR) in the NICU and the influence of antibiotic resistance on transmission. To evaluate the use of contour clamped homogeneous electric field (CHEF) gel electrophoresis in demonstrating spread of GNR in non-epidemic situations. Setting: 45 bed unit with care by two medical teams covering rooms 1&3 (team A) and 2&4 (team B). Ampicillin and gentamicin are used routinely for empiric treatment of sepsis.Methods: A prospective surveillance study. Sequential stool/rectal swab cultures were obtained on admission, weekly, and on discharge from 1/1-3/31/97. GNR were isolated on selective media, tested for gentamicin susceptibility, and typed by CHEF. Staff hand pool cultures were obtained in the last week of the study. Results: 239 infants had 561 cultures during the study period. 317(56%) cultures had GNR and 145(45%) cultures had>1 GNR for a total of 484 isolates; percentage positive increased linearly with age. 417(86%) isolates were gentamicin susceptible (GS) and 67(14%) were gentamicin non-susceptible (GNS). The species identified were:Klebsiella 184(38%), E.coli 151(31%),Enterobacter 74(15%), Citrobacter 46(10%),Pseudomonas 14(3%), Serratia 12(2%), others 3(1%). All 5 hand pools grew ≥1 GNR and 3 isolates were identical to strain types from colonized infants. Data for E. coli are presented.