RATIONALE: Giving antibiotics may be effective in preventing or controlling early infection in patients with multiple myeloma and may improve their response to chemotherapy.

PURPOSE: This randomized clinical trial is studying antibiotics to see how well they work compared to no antibiotics in preventing early infection in patients with multiple myeloma.

OBJECTIVES:

• Evaluate whether oral antibiotic prophylaxis with co-trimoxazole (TMP-SMX) versus ciprofloxacin (CPFX) or ofloxacin versus no prophylaxis will significantly reduce rates of serious bacterial infections during the first 3 months of chemotherapy in patients with multiple myeloma.
• Determine whether antibiotic prophylaxis with TMP-SMX or CPFX (or ofloxacin) is associated with an increased incidence of nonbacterial infection or an increased rate of infection from organisms resistant to prophylactic antibiotics.
• Evaluate whether oral antibiotic prophylaxis with CPFX or ofloxacin is as effective as TMP-SMX without the associated toxic effects.
• Evaluate whether protection against early infection in multiple myeloma patients can improve their response to initial chemotherapy.

OUTLINE: This is a randomized, multicenter study. Patients are stratified by participating center. Patients are randomized to 1 of 2treatment arms.

• Arm I: Patients receive co-trimoxazole every 12 hours for 2 months followed by observation for 2 months.
• Arm II: Patients receive oral ciprofloxacin or ofloxacin every 12 hours for 2 months followed by observation for 1 month.
• Arm III: The patient will receive no prophylaxis.

Patients continue their randomly assigned treatment throughout any infection in addition to any treatment needed for infection. Patients also remain on their randomly assigned treatment if chemotherapy is discontinued, changed, or delayed during the 3 month study.

Patients are followed at 6 months, 1 year, and 2 years.

PROJECTED ACCRUAL: A total of 212 patients (71 per treatment arm) will be accrued for this study.

Inclusion:

• Patient must have a diagnosis of multiple myeloma confirmed by the presence of:

• Bone marrow plasmacytosis with >10% abnormal plasma cells or multiple biopsy-proven plasmacytomas, and at least one of the criteria below must be documented:

  1. Myeloma protein in the serum
  2. Myeloma protein in the urine (free monoclonal light chain)
  3. Radiologic evidence of osteolytic lesions (generalized osteoporosis qualifies only if the bone marrow aspirate contains >20% plasma cells)

• Patients must have no active infection during the prior seven days and be off all antibiotics for the prior seven days.

• Patients cannot have received radiotherapy during the preceding ten days.

• Primary therapy for multiple myeloma must start within three days after entry to this study. For purposes of eligibility for this study, myelosuppressive chemotherapy or high-dose dexamethasone based regimens are acceptable as primary therapy. The high-dose dexamethasone regimen must include, at a minimum, dexamethasone 40 mg per day days 1-4, 9-12, 17-20 for the first cycle and 40 mg per day on days 1-4 of the second cycle.

• Patients who are to receive dexamethasone alone or dexamethasone with thalidomide are among those eligible for this protocol.

• Patients must have a serum creatinine <5.0 mg/dl and not require dialysis at the time of study entry. If patients require dialysis after enrollment, they can continue on the protocol using the adjusted medication guidelines

• Written informed consent must be obtained prior to entry.

Exclusion:

- Patients with smoldering myeloma, history of hypersensitivity to fluoroquinolones or trimethoprim, bone marrow transplant or autologous stem cell rescue planned during the first two months of treatment, patients taking theophylline, or patients previously treated with chemotherapy or high-dose dexamethasone