Cross-susceptibility of cefpirome and four other beta-lactams against isolates from haematology/oncology and intensive care units. International Study Group.

A multi-centre in-vitro study (8625 isolates) was conducted in 13 countries between May and November, 1992 to determine both the current bacterial epidemiology in intensive care and haematology/oncology units and the cross-susceptibility of the organisms to cefpirome, ceftazidime, ceftriaxone, imipenem and piperacillin. Bacterial species with 20 or more isolates resistant to one of the six antibiotics were examined for their susceptibility to the beta-lactams. Cefpirome and imipenem had the smallest total numbers of isolates. Bacteria resistant to ceftazidime or ceftriaxone were often susceptible (> 50%) to cefpirome. Conversely, cefpirome resistant isolates were frequently resistant (> 90%) to ceftazidime and ceftriaxone. P. aeruginosa was an exception, exhibiting cross-resistance to all cephalosporins. beta-lactamase producing Enterobacter, Citrobacter and Klebsiella spp. were especially resistant to piperacillin and ceftazidime but not cefpirome or imipenem. Two-thirds or more of coagulase-negative staphylococci resistant to any single agent, including imipenem, maintained their susceptibility to cefpirome. Cross-class resistance was not exhibited by imipenem and cefpirome against ciprofloxacin resistant isolates but was more evident for piperacillin, ceftazidime and ceftriaxone. Cefpirome was more active than ceftazidime against bacteria resistant to both piperacillin and gentamicin, especially coagulase-negative staphylococci (76% vs. 6%) and Enterobacter spp. (56% vs. 21%). Many coagulase-negative staphylococci and Enterobacter spp. susceptible to cefpirome (50-89%). These results suggest that cefpirome has a potential clinical advantage against gram-positive and gram-negative bacteria resistant to other beta-lactams, including imipenem.