Detection of biofilm production and antimicrobial susceptibility in clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa

Abstract

Acinetobacter baumannii and Pseudomonas aeruginosa are commensal which commonly colonize humans. As a result of their ubiquitous nature, reservoirs in hospital environment and resistance to many antimicrobial agents they are responsible for hospital – acquired infections. Additionally treatment of these infections is difficult because of the ability for biofilm formation. Aim of the paper was to determine the association between biofilm formation on medical devices and antibiotic resistance profile, compared to respiratory samples in clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa. Material and methods: The study comprised 50 clinical samples (36 from medical devices and 14 as а control group from respiratory secretions). Acinetobacter baumannii and Pseudomonas aeruginosa were identified by routine microbiological methods. Modification of the microtiter plate assay described by Stepanovic et al. was used to investigate the formation of biofilm. The antimicrobial susceptibility testing was performed according to EUCAST guidelines. Results:  Of the 50 analyzed strains, 16 (32%) were non-biofilm producers, and 34 (68%) were producing biofilms. Out of these, 29 (58%) were from medical devices, and 5 (10%) from the control group. Acinetobacter baumannii showed biofilm formation in 19 (67.9%), of which 17 (60.7%) from medical devices, and 2 (7.1%) from control group. Pseudomonas aeruginosa produced biofilm in 15 (68.1%), of which 12 (54.5%) from medical devices, and  3 (13.6%) from the control group. Multidrug resistance was detected in 40 (80%). All strains of Acinetobacter baumannii were multidrug resistant (MDR). For Pseudomonas aeruginosa, 11 (73.3%) biofilm forming isolates were MDR, and 1 (14.2%) non-biofilm forming isolate was MDR. Conclusion: Biofilm production was higher in strains from medical devices. Eighty percent of isolates were MDR. This is a serious challenge for treatment of these hospital-acquired infections.