multidrug resistant gram-negative bacilli in lower respiratory tract infections.

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.