Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 5 4 2013 12 15 323 327 EN Shashidhar Vishwanath Department of Microbiology, Kasturba Medical College, Manipal University, Manipal. India. Kiran Chawla Department of Microbiology, Kasturba Medical College, Manipal University, Manipal. India. Anusha Gopinathan Department of Microbiology, Kasturba Medical College, Manipal University, Manipal. India. 2015 10 16 Background: Lower respiratory tract infections are among important causes of morbidity and mortality for all age groups. The emergence of multidrug resistant Gram-negative bacilli is an issue of increasing concern. Materials and Methods: A retrospective study including respiratory specimens (sputum and BAL) was conducted in our tertiary care centre. Samples were processed for microscopy, culture and susceptibility testing following standard methods. Multidrug resistant Gram-negative bacilli causing lower respiratory tract infections were studied for their causation of disease. The effect of appropriate treatment on clinical outcome was observed. Results: A total of 472 Gram-negative pathogens were isolated from sputum and broncho-alveolar lavage fluid specimens during the study period. Among these Gram-negative pathogens 175 (37%) were found to be multidrug resistant. Klebsiella pneumoniae 85 (48.6%) and Acinetobacter spp. 59 (33.7%) were the predominant multidrug resistant Gram-negative bacilli isolated. Based on clinico-microbiological correlation, 138 (78.9%) multidrug resistant isolates were found to be pathogenic and the rest 37 (21.1%) were considered as colonizers. After initiating appropriate antibiotic therapy, clinical improvement was seen in 110 (79.7%) patients. In the patients who showed improvement, amikacin (34.3%) and cefoperazone-sulbactum (21.8%) were found to be the most effective drugs. Conclusion: A large majority of the isolated multidrug resistant Gram-negative bacilli were found to be pathogenic. Regular surveillance which directs appropriate empirical therapy; and good clinic-microbiological workup of each case of lower respiratory tract infection can reduce the morbidity and mortality associated with multidrug resistant organisms. https://ijm.tums.ac.ir/index.php/ijm/article/view/517 https://ijm.tums.ac.ir/index.php/ijm/article/download/517/292