Characterization of nonfermenters from clinical samples.

OBJECTIVE: Nonfermenters are a group of aerobic non sporing gram-negative bacilli found primarily free in nature and as commensals, whose pathogenic potentials are well established. The current study was conducted to assess the role of these nonfermenters in various infections and to characterize these isolates. METHODS: One hundred nonfermenters isolated from various clinical specimens were grouped according to Weaver-Hollis scheme based on growth on MacConkeys agar, oxidase activity and oxidation/fermentation of glucose. Species level identification was attempted based on a battery of biochemical tests. All isolates were then subjected to antimicrobial sensitivity. RESULTS: Majority of the isolates were encountered from pus and urine (50%). These isolates belonged to six of the seven Weaver-Hollis groups. Fifty six per cent of the isolates belonged to genus Pseudomonas. Multidrug resistance with resistance to more than three antimicrobials was frequently seen. Amikacin and ciprofloxacin were found to be most effective. CONCLUSION: Nonfermenting gram negative organisms are responsible for variety of infective conditions. Amongst them genus Pseudomonas and Acinetobacter calcoaceticus were more frequently encountered. Amikacin or ciprofloxacin (for nonfermenters other than Pseudomonas) appears to be the drug of choice for treatment of such infections.