Bactericidal activity of pigments isolated from Fars province (Iran) environmental bacteria on MDR clinical isolates of Acinetobacter

Antimicrobial agents are important compounds in reducing infections, but the spread of resistant pathogens diminished the effectiveness of these compounds. This study aimed to isolate the local bacterial pigments with specific antibacterial activity against clinical Acinetobacter baumannii isolates in burn centers. For this, pigmented bacteria isolated from environments in Fars province (Iran) and adjoining areas during Jun-July of 2017. Colonies with various pigment colors were isolated in pure cultures on nutrient agar. After identification of the pigmented bacteria, the extracted pigments were evaluated for antibacterial activity against previous confirmed clinical isolates of Acinetobacter baumannii with multi-drug resistant specification. Red pigment extract from Serratia marcescens (Prodigiosin) has the most proper inhibitory effect on the studied Acinetobacter baumannii isolates. The related bacterium was isolated from a salty region entitled Maharlo Lake. The minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) value of the pigment extracted from selected bacterium ranged from 2500-5000 µg/ml and 1250-2500µg/ml, respectively. The extracted pigments had a different antimicrobial activity against the studied clinical isolates, but on the basis of MBC/MIC results, the extracted prodigiosin pigment was the most effective anti-Acinetobacter agent. However, further studies are needed to use this pigment as a new antimicrobial agent or disinfectant on burn wounds.