Biofilm and metallo beta-lactamase production among the strains of Pseudomonas aeruginosa and Acinetobacter spp. at a Tertiary Care Hospital in Kathmandu, Nepal

INTRODUCTION: Pseudomonas aeruginosa and Acinetobacter spp. are found to be associated with biofilm and metallo-β-lactamase production and are the common causes of serious infections mainly in hospitalized patients. So, the main aims of this study were to determine the rates of biofilm production and metallo beta-lactamase production (MBL) among the strains of Pseudomonas aeruginosa and Acinetobacter spp. isolated from hospitalized patients. METHODS: A total of 85 P. aeruginosa isolates and 50 Acinetobacter spp. isolates isolated from different clinical specimens from patients admitted to Shree Birendra Hospital, Kathmandu, Nepal from July 2013 to May 2014 were included in this study. The bacterial isolates were identified with the help of biochemical tests. Modified Kirby-Bauer disc diffusion technique was used for antimicrobial susceptibility testing. Combined disc diffusion technique was used for the detection of MBL production, while Congo red agar method and tube adherence method were used for detection of biofilm production. RESULTS: Around 16.4% of P. aeruginosa isolates and 22% of the strains of Acinetobacter spp. were metallo β-lactamase producers. Out of 85 P. aeruginosa isolates, 23 (27.05%) were biofilm producers according to tube adherence test while, only 13 (15.29%) were biofilm producers as per Congo red agar method. Similarly, out of 50 Acinetobacter spp. 7 (14%) isolates were biofilm producers on the basis of tube adherence test, while only 5 (10%) were positive for biofilm production by Congo red agar method. Highest rates of susceptibility of P. aeruginosa as well as Acinetobacter spp. were seen toward colistin. CONCLUSION: In our study, biofilm production and metallo beta-lactamase production were observed among Pseudomonas aeruginosa and Acinetobacter spp. However, no statistically significant association could be established between biofilm production and metallo beta-lactamase production.