The purpose of the study is to find out if high dose antibiotic (meropenem, MERREM® I.V.), along with another drug called an aminoglycoside (a different type of antibiotic) is effective in decreasing or reducing the rate of antibiotic resistant Pseudomonas aeruginosa, Acinetobacter (germs that can cause pneumonia), and the rate of resistance in other difficult to treat germs which may cause hospital-acquired pneumonia requiring mechanical ventilatory support. The study hopes to show that by increasing the amount of meropenem administered and increasing the duration of infusion (release of the drug into the bloodstream), levels of the drug will stay at target levels in the bloodstream and decrease the ability of difficult to treat germs to resist, or not be killed by, the treatment using this antibiotic (meropenem) or other antibiotics.

• Drug: MERREM I.V. 2g as a 3 hour infusion every 8 hours
• Drug: vancomycin I.V. 1 g every 12 hours
• Drug: tobramycin I.V. 5 mg/kg every 24 hours
• Drug: MERREM I.V. 1g as a 30 minute infusion every 8 hours
• Drug: MERREM I.V. 500 mg as a 3 hour infusion every 8 hours

Inclusion Criteria:

• Onset or exacerbation of pneumonia at least 72 hours after admission to an acute care facility or onset of pneumonia in a nursing home or rehabilitation facility with subsequent transfer to an acute care facility
• Diagnosis of hospital-acquired pneumonia requiring mechanical ventilatory support
• Patient or Patient’s legal guardian must sign written informed consent for study participation, pretreatment, and Day 7 bronchoscopy

Exclusion Criteria:

• Patients with hospital-acquired pneumonia caused by pathogens resistant to MERREM
• Patients with allergies to cephalosporins, penicillins and carbapenems
• Patients taking anticonvulsant therapy for a known seizure disorder
• Patients with lung cancer
• Patients with cystic fibrosis, acquired immune deficiency syndrome (AIDS), neutropenia, active tuberculosis, or patients taking immunosuppressive therapy in preparation for or following an organ transplant.
• Patients who are pregnant or breast feeding
• Patients who are unlikely to survive
• Patients with certain infections in another area requiring treatment with additional antibiotics
• Patients with other underlying conditions that would make it difficult to interpret response to study drug.
• Patients who have been part of another clinical study 30 days before entry into this study.
• Patients with hypotension (systolic BP < 85mmHg) or acidosis (arterial pH <7.25 or serum bicarbonate <15 mg/dl) despite attempts at fluid resuscitation
• Patients with profound hypoxia