Investigation of biofilm in Acinetobacter baumannii isolated from lower respiratory tract specimen

In 2018 World Health Organization published a top list of bacteria that needed a new antibiotic discovery, and A. baumannii is on the list. The biofilm structure of bacteria, which plays a role in antibiotic resistance, also guide an explaining its relationship with the diseases. A. baumannii causes serious nosocomial infections such as ventilator-associated pneumonia, septicemia, and catheter-associated bacteremia. This study aimed to investigate biofilm in Acinetobacter baumannii isolates isolated from lower respiratory tract samples. Biofilm presence was studied on the microtitration plate method. A few colonies taken from fresh cultures of A.baumannii isolates passaged on blood agar with the help of a sterile loop were placed in tubes containing 0.25% glucose TSB and incubated at 37°C overnight. Cultures were diluted 1/20 and 200 µl was transferred to a 96-well flat-bottom polystyrene microtiter plate and incubated at 37°C overnight. After incubation, the liquid medium was poured, and the wells were washed 3 times with distilled water and dried by inverting on blotting paper. After distributing 100 µl of 1% crystal violet solution to the wells, it was incubated for 15 minutes at room temperature. After incubation, the wells were washed 3 times with distilled water and dried by inverting on blotting paper. After adding 200 µl of ethanol/acetone (80:20) to the wells, the dye was to disssolved for 10 minutes. Plates were read in an optical ELISA reader with a 540n filter wavelength. The study collected 55 samples, 12 samples were non-biofilm forming, and 43 samples were biofilm-forming. The antibiotic resistance status of amikacin, gentamicin, and imipenem in biofilm-forming samples (67%, 93%, 100%), whereas in non-biofilm-forming samples (58%, 83%, 100%) respectively. As a result, biofilm and resistance status in Acinetobacter baumannii isolates isolated from lower respiratory tract samples are important in the treatment of infection related to this bacterium.