Antibiotic Susceptibility of Resistant Pseudomonas Species Generated Through the Use of Differential and Selective Media for Isolation of Pseudomonas from Environmental Samples

Abstract

Water and soil samples were cultured on Cetrimide agar, Kings B agar, and nutrient agar supplemented with 50 μg.mL-1 chloramphenicol for the isolation of greenish pigment producing Pseudomonas species. Greenish pigment producing colonies that grew on the media were subjected to microscopic examination and selected physicochemical/biochemical tests to confirm that they belong to the Pseudomonas genus. Isolates confirmed to belong to the Pseudomonas genus were subjected to antibiotic susceptibility testing to various antibiotics using the disc diffusion method. The antibiotic sensitivity testing showed that two of the Pseudomonas isolates from nutrient agar plates supplemented with chloramphenicol showed resistance to Ampiclox, Rifampicin, and Norfloxacin. Also, one of the isolates showed resistance to Gentamycin, Amoxicillin, and Amoxicillin clavulanate. Two of the isolates from Kings B medium showed resistance to Ampiclox; another isolate showed resistance to Rifampicin, and one of the isolate that showed resistance to Ampiclox also showed resistance to Rifampicin, Chloramphenicol and Norfloxacin. Only one isolate from Cetrimide agar showed resistance to Ofloxacin and Nalidixic acid. Based on the EUCAST Breakpoint Table for P. aeruginosa, 12 out of the 14 Pseudomonas isolates (85.7%) were susceptible to Levofloxacin and Gentamycin, while 8 (57.1%) of the isolates were susceptible to Ciprofloxacin. The results indicate that Pseudomonas species isolated from the environment through the use of differential and selective media can become resistant to some antibiotics, and that Levofloxacin and Gentamycin could be used in the treatment of infections caused by antibiotic resistant Pseudomonas.