2. Diagnosis of chronic lymphocytic leukaemia (CLL), multiple myeloma (MM) or non-Hodgkin lymphoma (NHL).
3. Patients must be receiving Ig (IV or subcutaneous - SCIg) replacement for prevention of bacterial infections due to hypogammaglobulinaemia for longer than 6 consecutive months.
4. Patient is eligible for trial of Ig cessation in the opinion of the treating clinician and local investigator.
5. Life expectancy greater than 12 months.
6. Able to give informed consent, and willing and able to comply with each of the treatment arms.
You may not be if
1. Prior or planned allogeneic haematopoietic stem cell transplantation.
2. Major infection (Grade 3 or higher) in preceding 3 months, and/or current active infection requiring antimicrobial treatment.
3. Already receiving daily antibiotic prophylaxis for the purpose of preventing bacterial infection (Note: patients may receive antiviral, antifungal and Pneumocystis jirovecii pneumonia (PJP) prophylaxis).
4. Intolerance of all trial antibiotic options in either arm A or arm B.
5. Communication, compliance or logistical issues that are likely to limit patient's ability to take prophylactic or emergency antibiotics, or to obtain urgent medical attention for symptoms of infection.
6. Pregnant or breastfeeding.
7. Severe renal impairment (estimated or measured creatinine clearance of less than 30 mL/min).
8. Previous splenectomy.
9. Previous participation in this trial.
10. Treating team deems enrolment in the study is not in the best interests of the patient.
