Selection of an empiric antibiotic regimen for hospital-acquired pneumonia using a unit and culture-type specific antibiogram.

The objective of this retrospective study was to determine the optimal initial antibiotic regimen for hospital-acquired pneumonia using the frequency and sensitivity of Gram negative microorganisms found in sputum cultures. An antibiogram was constructed and compared with the hospital intensive care unit (ICU) antibiogram. The results yielded 191 microorganisms. The study-generated antibiogram showed that the highest percent susceptible antibiotics for all Gram-negative microorganisms were imipenem (75%) and amikacin (84%). Considering only Pseudomonas aeruginosa, the study-generated antibiogram and the hospital ICU antibiogram showed similar results, piperacillin and amikacin (86% and 82%, respectively, vs 91% and 85%, P = nonsignificant for both). The optimal empiric antibiotic regimen in the surgical ICU is different if directed against all possible microorganisms as opposed to the most prevalent microorganism P aeruginosa. Determining initial empiric antibiotic therapy using an ICU and culture-type specific antibiogram would result in a greater likelihood that more patients would receive adequate initial antibiotic therapy.