This is a phase 2a, multinational, multicenter, double-blind, randomized, placebo-controlled, dose-ranging safety, tolerability and PK study in patients with HABP (Hospital Acquired Bacterial Pneumonia) or VABP (Ventilator Associated Bacterial Pneumonia) caused by ABC to identify safe and well-tolerated doses and to assess the PK profile of OMN6 in patients.

Inclusion Criteria:

1. A signed informed consent form.
2. Male or female patients 18 years or older
3. A diagnosis of either a HABP or a VABP
4. ABC infection of the lower respiratory tract suspected based on a positive rapid testing of respiratory specimens
5. Women of childbearing potential (WOCBP) (i.e., not post-menopausal or surgically sterilized) must have a negative highly sensitive urine or serum pregnancy test before randomization.
6. Acute Physiology and Chronic Health Evaluation II (APACHE II) score between 10 and 24

Exclusion Criteria:

1. Moderate to severe reduction of renal function
2. Liver dysfunction
3. Evidence of septic shock
4. Acute respiratory distress syndrome.
5. Immunosuppressed patients (due to either immunosuppressant drugs or to any medical condition).
6. History of any known hypersensitivity to colistin or to carbapenems
7. Any condition or circumstance that, in the opinion of the investigator, would compromise the safety of the patient or the quality of the study data