Introduction

Background Myeloma is a cancer of bone marrow plasma cells that causes anaemia, skeletal fractures, renal failure and profound immunodeficiency. There are approximately 5500 new cases of myeloma in the UK per annum.(1) However, the overall prevalence is increasing, given the improved survival rates over the past four decades.(2) The median age at presentation is approximately 70 years and only 15% of patients are aged < 60 years. Myeloma has a higher incidence in African-Caribbean ethnic groups than in Caucasians, but there are few other distinctive epidemiological features.(3) The majority of cases present de novo, but it is now recognised that this is preceded by an asymptomatic monoclonal gammopathy of undetermined significance phase in virtually all patients.(4) Myeloma causes profound immunodeficiency and recurrent serious infections. One-quarter of patients will have a serious infection within 3 months of diagnosis. Ten per cent of patients die within the first 60 days of diagnosis, with bacterial infection directly causing 45% of these deaths.(5) Recent advances in antimyeloma treatment have improved overall survival significantly, yet this high early-death rate remains little changed, affecting all prognostic groups. Patients who may have survived long term with current antimyeloma treatment are dying soon after diagnosis, with the biggest single cause being bacterial infection. Therefore, newly diagnosed myeloma patients may benefit from antibacterial prophylaxis to prevent infection, hospital admission and early death. Reducing infection may also improve response to antimyeloma treatment by reducing interruptions of antimyeloma treatment and reducing immune responses to infection that promote myeloma cell survival and growth. In patients with other causes of immunodeficiency, such as neutropenia, asplenia, human immunodeficiency virus infection or reflux nephropathy, the importance of prophylactic antibiotics to prevent infection is well established and the administration of prophyactic antibiotics is common practice in the NHS. However, their usefulness in myeloma has not been established. Furthermore, some of the studies that established the use of antibacterial prophylaxis in other conditions predate the current rise in health care-associated infections (HCAIs), such as Clostridium difficile. The data from these older trials may not reflect current risks associated with antibiotic prophylaxis and so there is a need to reassess the effect of antibiotic prophylaxis on HCAI.