The Impact of Minimum Inhibitory and Sub Inhibitory Concentrations of Antibiotics on Acinetobacter baumannii and Pseudomonas aeruginosa Biofilm Production

THESE bacteria are opportunistic bacterial pathogens, it are associated with hospital acquired infection and have high propensity to acquire a wide range of antibiotic resistance determents. This study aimed to investigate the biofilm-forming capacities of Acinetobacter baumannii and Pseudomonas aeruginosa, as well as any possible correlations between the production of biofilms and exposure to different sub-lethal antibiotic dosages. The selected isolates were taken from the University of Mosul's bacterial culture collections and assessed qualitatively as well as quantitatively using standard procedures. Antimicrobial susceptibility, biofilm formation and inducibility were used. The biofilm cells showed an impressive increase in the minimum inhibitory concentrations (MICs) of various antibiotic groups. Most of the representative isolates treated to various sub-lethal antibiotic doses (1/8, 1/4, and 1/2 the MIC) showed a considerable induction of biofilm creation. For A. baumanii the induction of a biofilm formation was decrease with presence of ceftazidime, while the biofilm formation was increase in the presence of amikacin, the biofilm formation was decrease in the presence of gentamicin, biofilm formation was decrease in the presence of levofloxacin. Increased biofilm formation in the presence of meropenem and tetracyclinel, 7.8 mg/ml to 31.2 mg/ml respectively. Similar results were shown for the P. aeroginosa isolate, where biofilm formation was induction in the presence of concentration of the antibiotics amikacin, ceftazidime, gentamicin, and levofloxacin, while concentrations of meropenem and tetracycline showed a decrease in biofilm formation. This study suggests a connection between low-dose antimicrobial medication and an increased risk of A. baumannii and P. aeroginosa biofilm infections by highlighting a potential role for efflux pump and transport of auto-inducer molecules during biofilm production. Information from this study will be helpful in developing antibiofilm approaches.