This study will consist of two parts.
Part 1 - Dose regimen selection: An open-label, 30 patient, 3-arm PK assessment of: Arm 4 (previously 1): LBP-EC01 (approximately 2×10^12 PFU) given by IU administration on D1 and D2 and LBP-EC01 (approximately 1×10^11 PFU) IV given as a 1 milliliter (mL) bolus QD from D1 through D3 concomitantly with oral trimethoprim/sulfamethoxazole (TMP 160mg/SMX 800mg) BID from D1 through D3 (6 doses); Arm 5 (previously 2): LBP-EC01 (approximately 2×10^12 PFU) given by IU administration on D1 and D2 and LBP-EC01 (approximately 1×10^10 PFU) IV given as a 1 mL bolus QD from D1 through D3 concomitantly with oral TMP/SMX BID from D1 through D3 (6 doses); Arm 6 (previously 3): LBP-EC01 (2×10^12 PFU) given by IU administration on D1 and D2 and LBP-EC01 (approximately 1×10^12 PFU) IV given as a 100 mL IV infusion over 2 h on D1 through D3 concomitantly with oral TMP/SMX BID from D1 through D3 (6 doses).
Part 2 - Efficacy, Safety, Tolerability and Pharmacokinetics: A blinded, 288 patient, 1:1 randomized evaluation of the Arm 4 dose regimen, selected from Part 1, versus placebo + antibiotic (TMP/SMX -160 mg TMP and 800 mg SMX) given orally BID on Days 1 through 3.