Nonfermenting gram-negative bacilli infections in a tertiary care hospital in Kolar, Karnataka

Abstract

Aim : Nonfermenting gram-negative bacilli (NFGNB), which are saprophytic in nature, have emerged as important healthcare-associated pathogens. They exhibit resistance not only to beta lactam and the other groups of antibiotics, but also to carbapenems. This study was undertaken to identify the nonfermenters isolated from various clinical samples, to assess their clinical significance, to know the type of healthcare-associated infections they caused, and to know their anti-microbial sensitivity pattern. Materials and Methods : The nonfermenters were identified using a standard protocol that included tests for motility, oxidase production, oxidation-fermentation test for various sugars, gelatin liquefaction, and growth on 10% lactose agar. The clinical significance was assessed by using various criteria and susceptibility testing was performed with the help of the Kirby-Bauer disc diffusion method. Results : A total of 193 NFGNB were isolated from 189 clinical specimens. Pseudomonas aeruginosa was the most common nonfermenter, accounting for 53.8%, followed by Acinetobacter baumannii (22.2%), and Pseudomonas fluorescens (10.8%). Other significant NFGNB isolated were: Sphingobacterium species (5.2%), Acinetobacter lwoffii (3.1%), and Stenotrophomonas maltophilia (2.6%). P. aeruginosa showed good sensitivity to imipenem (94%), cefoperazone (70%), amikacin (69%), and ticarcillin (63%). A. baumannii showed 100% sensitivity to imipenem and 70% sensitivity to piperacillin. Conclusion : P. aeruginosa and A. baumannii were the common NFGNB isolated in our study from patients of, urinary tract infection, bacteremia, surgical site infections, and ventilator associated pneumonia. P. aeruginosa showed good sensitivity to imipenem, amikacin, and cefoperazone while A. baumannii showed good sensitivity to imipenem and piperacillin.