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

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. 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. 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. 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.