The significance of aerobic gram-negative bacilli in clinical specimens following orthotopic liver transplantation.

In a prospective study of 284 liver transplant patients, we sought associations between aerobic gram-negative bacillus acquisition or infection and 35 preoperative, perioperative, and postoperative variables. Although the 128 (45%) who acquired aerobic gram-negative bacilli had longer admissions (P = 0.0001), no associations were found with pretransplant variables. Fifty-three (41%) of the 128 acquired coliforms (e.g., Escherichia coli, Klebsiella spp., or Enterobacter spp.), 50 (39%) acquired nonfermentative bacilli (e.g., Acinetobacter spp., Pseudomonas spp., or Stenotrophomonas maltophilia), and a further 25 (20%) acquired both. Acquisition progressed to infection in 58% of patients who acquired coliforms but in only 18% of patients who acquired nonfermentative bacilli (P = 0.005). Acinetobacter spp. were isolated from more patients than other bacilli but rarely caused infection. The positive predictive values for infection of acquiring coliforms or nonfermentative bacilli in clinical material were 42% and 17%, respectively. This study allowed us to determine for each clinical site the positive predictive values for infection of acquisition of different aerobic gram-negative bacilli. Our results should contribute to the rationalization of antimicrobial prescribing for this patient group.