Antibiotic resistance among gram-negative bacteria of lower respiratory tract secretions in hospitalized patients

Data on antibiotic resistance pattern of gram-negative bacterial isolates of lower respiratory tract secretions of hospitalized patients were fed into WHONET computer and analyzed for the year 1999. Out of 860 samples, 269 (31.2%) were culture positive. Gram-negative bacteria (GNB) accounted for 238 (88.4%) positive samples. Non-fermenting gram-negative bacteria (NFGNB) were found in 34% samples, the other common ones being Klebsiella spp (29.8%) and Pseudomonas spp (17.2%). GNB isolates from tracheal aspirates and sputum were 132 (55.4%) and 106 (44.5%) respectively. Adults (32.7%) and elderly patients (24.3%) recorded higher isolation of GNB as compared to pediatric patients (1.6%). The highest mean resistance among predominant GNB in both tracheal aspirate (96.6%) and sputum (86.9%) was noted to ampicillin while the lowest mean resistance in tracheal aspirate (28%) and sputum (14.3%) was to amikacin. NFGNB of tracheal aspirates and sputum showed highest resistance of 50% and 32% to amikacin, respectively. Pseudomonas spp showed the highest variation in the resistance pattern between tracheal aspirates and sputum samples. Overall mean resistance was highest among tracheal aspirate isolates compared to sputum isolates.