Evolution, incidence, and susceptibility of bacterial bloodstream isolatesfrom 519 bone marrow transplant patients

Bacteria remain an important cause of infection in bone marrow transplants. To examine shifts in the etiology and susceptibility of bacterial isolates from transplants, we reviewed the incidence and susceptibility of blood is olates during a 7-year period. The infection rate fell dramatically during this time. Gram-positive organisms were isolated more often than gram-negat ive organisms, but the trend is reversing. Streptococci surpassed staphyloc occi for 5 years as the leading pathogen. Increasing resistance to penicill in, ciprofloxacin, and imipenem was noted in Streptococcus species. With th e exception of type 1 beta -lactamase-producing bacteria and Pseudomonas ae ruginosa, gram-negative isolates remained overall susceptible to ceftazidim e. Increased antibiotic prophylaxis coincided with the reduction in percent age of infected patients and increase in resistance to beta -lactam antibio tics. Mortality attributed to bacteremia was low except for infections caus ed by P. aeruginosa and the Enterobacter, Serratia, Citrobacter group. Ther e was no mortality attributable to gram-positive organisms such as Staphylo coccus aureus and viridans streptococci.