- This study was devised to look at trends in the microbiological spectrum and susceptibility patterns of pathogens causing bacteraemia in paediatric febrile oncology patients. The retrospective study compared various microbiological aspects recorded for febrile oncology neutropenic patients treated with two different empirical antibiotic regimens (ceftazidime plus gentamicin during 1998–1999 and piperacillin/tazobactam plus amikacin during 2000–2002). Eighty-one bacteraemic episodes occurred in 41 patients. Overall, 132 (34 during 1998–1999 and 98 during 2000–2002) organisms were isolated: 84 (65%) Gram-negative bacteria, 39 (30%) Gram-positive bacteria and 7 (5%) fungi. Enterobacter spp. incidence decreased from 18 to 6% ( P = 0.07) while the recovery rates of Gram-positive organisms increased from 24 to 32% ( P = 0.4) during 2000–2002 compared with 1998–1999. MRSA were not isolated from any episode of bacteraemia. Five (18%) of the 28 Escherichia coli and Klebsiella spp. isolates were β-lactamase producers (80% [4/5] isolated during 2000–2002). Twenty-seven of 28, 27/27, 23/28, 20/25 and 27/28 of these isolates were susceptible to imipenem, piperacillin/tazobactam, gentamicin, ceftazidime and ciprofloxacin, respectively. Thirty-two of 34 (94%) and 60/74 (81%) of the Gram-negative organisms isolated during 2000–2002 were susceptible to piperacillin/tazobactam and ceftazidime, respectively ( P = 0.076). No major differences in the microbial spectrum and antibiotic susceptibilities were recorded between the two consecutive study periods. An increase in the number of extended β-lactamase producing E. coli and Klebsiella spp. occurred during 2000–2002. All β-lactamase producing organisms were susceptible to piperacillin/tazobactam and initial empirical therapy with piperacillin/tazobactam was more appropriate than ceftazidime to cover most of the pathogens causing bacteraemia.