Antibiotic Susceptibility of Bloodstream Isolates in a Pediatric Oncology Population: The Case for Ongoing Unit-specific Surveillance.

Fever in a neutropenic oncology patient requires rapid initiation of effective empiric antibiotics to prevent mortality. We evaluated the appropriateness of our current empiric antibiotic regimen by assessing local antibiotic-susceptibility patterns in our pediatric oncology patients, and comparing them to the general pediatric patterns in our hospital. All blood culture isolates from pediatric oncology patients were reviewed over a 3-year period. Gram-negative and Gram-positive organisms were reviewed separately, with antibiotic susceptibilities for all unique isolates evaluated, and antibiograms generated and compared with general pediatric patients via the Fisher exact test. A total of 84% of Gram negatives were susceptible to meropenem; all resistant organisms were Pseudomonas aeruginosa, with 50% meropenem susceptibility. A total of 91% of Gram negatives were susceptible to cefepime, including 90% of P. aeruginosa and 80% of Escherichia coli. In total, 96% of Gram positives were vancomycin-susceptible; the only resistant organism was a single enterococcal isolate. In comparison with the general pediatric population, significantly fewer pseudomonal isolates were sensitive to meropenem among the oncology population (50% vs. 89%, P=0.0034). As such, in our population, meropenem does not provide adequate monotherapy against Pseudomonas. Ongoing surveillance of antibiotic resistance in this high-risk population is warranted, to ensure appropriate empiric antibiotic usage.