Identification of Antibiotics Susceptibility Patterns at Sub-inhibitory Concentrations in Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is a Gram negative bacterium that has been recognized as an opportunistic pathogen. It is the most common bacterium associated with nosocomial infections and ventilator-associated pneumonia. It exhibits high innate resistance to various ranges of antibiotics thereby causing high morbidity and mortality rate. This research was aimed to identify the antibiotics susceptibility patterns at sub-inhibitory concentration in Pseudomonas aeruginosa. One hundred and fifty (150) clinical swab specimens were collected from urinary catheters; wound and ear infections of patients and the swabs inoculated using standard microbiology method. The isolates were characterized based on the bacteriological methods such as morphology and biochemical tests. The isolates were further confirmed by species specific by PCR amplification of 16S rRNA and the amplicons were analyzed by gel electrophoresis; and further genomic sequencing was done and blast with NCBI database mining. The antimicrobial susceptibility of the isolates was done by disc diffusion methods. The result of the isolation showed 22(59.46%) from wound infections, 12(32.43%) from ear infections and 3(8.11%) from urinary catheter. The isolates were Gram-negative, produced β-hemolysis on blood agar and the morphology is small pigmented circular. The isolates showed positive results to catalase, oxidase, citrate, nitrate and indole tests. The amplification of the 16S rRNA gene region resulted in the band size of 1500bp PCR product and the BLAST analysis gave 99% similarity. The results of susceptibility analysis showed that the isolates from the urinary catheter, wound and ear infection were 82%, 68% and 47% respectively, resistance to Piperacillin tazobactem, Cefoperazon, Ofloxacin, Tetracycline, Amikacin, Gentamycin, Bacitracin, Clarithromycin, Cefalotin, Levofloxacin and Cefpiroma. Antimicrobial susceptibility tests in P. aeruginosa isolates revealedshowed that they were multi-drug resistant. At sub-inhibitory concentrations of antibiotics within the microbial environment, Pseudomonas aeruginosa becomes more resistant. Perhaps, these antimicrobials could have other signaling activities within the environment. Therefore, there is a need for more research work to develop therapeutics combination to combat the recalcitrant nature of Pseudomonas aeruginosa.