Bacteriological analysis.

Collection of lungs was carried out daily from day 1 until day 7 for all groups. Lungs were excised, weighed, and then subjected to homogenization in 10 mL of normal saline. Plating of serially 10-fold-diluted homogenates was performed using tryptone soy agar. Data were expressed as mean values of log₁₀ CFU per gram of lung tissues, and the standard deviation (SD) was also calculated. Bactericidal effect was defined as a ≥3-log₁₀ reduction compared to the initial count at zero time. For synergy, it was defined as a ≥2-log₁₀ reduction with drug combinations compared to the values for the most active single drug. Experiments were carried out in triplicate.