Antibiotic sensitivity pattern of gram negative bacilli isolated from the lower respiratory tract of ventilated patients in the intensive care unit

Background: Lower respiratory tract infections (LRTIs) are the most frequent infections among patients in Intensive care units (ICUs). Aims: To know the bacterial profile and determine the antibiotic susceptibility pattern of the lower respiratory tract isolates from patients admitted to the ICU. Settings and Design: Tertiary care hospital, retrospective study. Materials and Methods: Transtracheal or bronchial aspirates from 207 patients admitted to the ICU were cultured, identified, and antibiotic sensitivity was performed by standard methods. Statistical Analysis Used: SPSS software was used for calculation of % R of 95% confidence interval (CI). Results: Of 207 specimens, 144 (69.5%) were culture positive and 63 (30.4%) showed no growth. From 144 culture positives, 161 isolates were recovered, of which 154 (95.6%) were Gram negative bacilli (GNB). In 17 (11.0%) patients, two isolates per specimen were recovered. The most common GNB in order of frequency were Pseudomonas aeruginosa (35%), Acinetobacter baumannii (23.6%), and Klebsiella pneumoniae (13.6%). A very high rate of resistance (80-100%) was observed among predominant GNB to ciprofloxacin, ceftazidime, co-trimoxazole, and amoxycillin/clavulanic acid combination. Least resistance was noted to meropenem and doxycycline. Conclusion: Nonfermenters are the most common etiological agents of LRTIs in ICU. There is an alarmingly high rate of resistance to cephalosporin and β-lactam-β-lactamase inhibitor group of drugs. Meropenem was found to be the most sensitive drug against all GNB. Acinetobacter and Klebsiella spp. showed good sensitivity to doxycycline.

Keywords
Antibiotic susceptibility, gram negative bacilli, intensive care unit, ventilated patients