Longitudinal surveillance of bacteraemia in haematology and oncology patients at a UK cancer centre and the impact of ciprofloxacin use on antimicrobial resistance.

OBJECTIVES: To assess and compare the current trends in bacteraemia and antimicrobial resistance and analyse the impact of ciprofloxacin prescribing on Gram-negative bacterial resistance in haematology and oncology patients.
METHODS: Information on bacteraemia episodes, causative pathogens, antimicrobial resistance and consumption was compared between haematology and oncology patients at a UK cancer centre in a 14 year longitudinal surveillance study.
RESULTS: Haematology patients had a 3-fold higher incidence of bacteraemia compared with oncology patients (10.9/1000 versus 3.6/1000 admissions, respectively). Coagulase-negative staphylococci were the most common Gram-positive cause of bacteraemia for both cancer groups, whereas the overall rate of methicillin-resistant Staphylococcus aureus bacteraemia was low (0.16/1000 admissions). Escherichia coli was the most common Gram-negative cause of bacteraemia for both groups, but with a higher incidence in haematology patients (0.92/1000 admissions) compared with oncology patients (0.5/1000 admissions). Pseudomonas spp. formed the second most common Gram-negative infection in haematology patients, with a 4-fold higher bacteraemia incidence compared with oncology patients (0.76 versus 0.16/1000 admissions). Ciprofloxacin resistance of Gram-negative isolates was 22% in haematology and 5% in oncology patients. The rate of ciprofloxacin use measured showed high ciprofloxacin consumption in haematology patients compared with oncology patients (3.6 versus 1.5 defined daily doses/10 admissions, respectively), suggesting that ciprofloxacin may drive resistance.
CONCLUSIONS: Our longitudinal surveillance highlights the continued importance of Gram-negative bacteraemia, in particular that due to Pseudomonas, in the cancer population and raises concerns regarding increasing ciprofloxacin use and resistance.