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The increasing rate of resistance to antimicrobial agents is a public health challenge and Pseudomonas aeruginosa is known to have recalcitrant resistance to several antibiotics. In this study, we characterized antimicrobial resistance and multiple antibiotic resistance (MAR) index of P. aeruginosa of environmental and clinical origin. A total of 240 samples were examined, of which 120 each were of environmental and clinical settings. Bacteriological analysis, antimicrobial sensitivity and MAR were performed on the isolates. The results revealed that of the 120 clinical matrixes evaluated for the presence of P. aeruginosa, 54.16% (65/120) were positive for P. aeruginosa. There were significant differences among the clinical samples (p < 0.05) in prevalence. The highest isolation rate 27.7% was observed in wound samples and the least 10.8% in urine. For environmental samples, 45.83% (55/120) were positive for P. aeruginosa. There was a highly significant difference among the environmental samples (p < 0.01) in prevalence. All positive isolates were resistant to cefuroxime (100%) and amoxicillin (100%). Most were also resistant to nalidixic acid (88%), cotrimoxazole (86%) and ciprofloxacin (85%). There was high significant difference in the resistance patterns of the isolates at p<0.001. All the isolates were multi-resistant revealed by the high MAR index profile. The multi-resistance exhibited by P. aeruginosa further confirms the call for integrated approaches to combat bacterial antibiotic resistance.

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The presence of integrons and antibiotic resistance genes in the genome of Pseudomonas aeruginosa pose a serious problem in the treatment and control of infections caused by this pathogen in hospitals. This study was carried to analyse the presence of class 1 integrons and some antibiotic resistance genes on selected clinical and environmental strains of Pseudomonas aeruginosa. A total of 120 strains were employed for this study.The strains were confirmed using molecular method and species-specific primers targeting the 16S ribosomal ribonucleic acid (rRNA). Polymerase chain reaction (PCR) was used to detect the presence of class 1 integrons and resistance genes using appropriate primers and conditions. The strains were analysed for the presence of the following antibiotic resistance genes - aadA, blaPSE, blaAMPC, blaIMP and tetC encoding  aminoglycosides, betalactamases, metallo-beta-lactamases (MBL) and tetracylines resistance respectively. On screening the isolates for the presence of class 1 integrons, 50/60 (83.3 %) clinical isolates and 46/60 (76.7 %) environmental isolates showed positive results (P > 0.05). In both clinical and environmental isolates, the highest occurring resistance genes were blaAMPC and tetC (encoding beta-lactamases and tetracylines respectively), while the least was observed in blaIMP (encoding metallo-beta-lactamases). In comparison, there was high significance difference (at P<0.01 significance level) in the resistance gene blaPSE between the clinical and environmental strains. The high prevalence of these resistance genes is a great threat in the treatment of Pseudomonas infections. Keywords: Pseudomonas aeruginosa, Resistance genes, Integrons, Beta-lactamases.