Occurrence and antimicrobial susceptibility of gram-negative nonfermentative bacilli in cystic fibrosis patients.

Isolation of nonfermentative gram-negative bacilli (other than Pseudomonas aeruginosa) from respiratory tract cultures of cystic fibrosis (CF) patients has increased in recent years. Species recovered include Pseudomonas cepacia, P. maltophilia, P. fluorescens/putida, P. alcaligenes, P. pseudoalcaligenes, P. stutzeri, Acinetobacter spp., Achromobacter xylosoxidans, Flavobacterium spp., and CDC groups IVe and Ve. Although colonization with most of these organisms is sporadic, P. cepacia (and to a lesser extent, P. maltophilia) is usually isolated consistently, and can be associated with significant clinical deterioration. Occurrence of P. cepacia in CF respiratory tract cultures obtained close to the time of death rose nearly ten-fold from 1979 to 1982. Strains representing all nonfermentative gram-negative species encountered were assayed for susceptibility to 17 newer antimicrobial agents. Ceftazidime, n-formimidoyl thienamycin, and aztreonam were most active; cefsulodin, ceforanide, and ceftriaxone were not active against these isolates.