Antibiotic susceptibility patterns of Pseudomonas aeruginosa at a tertiary care hospital in Gujarat, India

Abstract

Objectives: The present study was undertaken to assess the antibiotic susceptibility patterns of Pseudomonas aeruginosa at a tertiary care hospital in Gujarat, India. Due to significant changes in microbial genetic ecology, as a result of indiscriminate use of anti-microbials, the spread of anti-microbial resistance is now a global problem.

Materials and methods: Out of 276 culture positive samples, 56 samples of Pseudomonas aeruginosa were examined and 10 different types of specimen were collected. Microbial sensitivity testing was done using disk diffusion test with Pseudomonas species NCTC 10662, as per CLSI guidelines.

Results: The highest number of Pseudomonas infections was found in urine, followed by pus and sputum. Pseudomonas species demonstrated marked resistance against monotherapy of penicillins, cephalosporins, fluoroquinolones, tetracyclines and macrolides. Only combination drugs like Ticarcillin + Clavulanic acid, Piperacillin + Tazobactum, Cefoperazone + Sulbactum, Cefotaxime + Sulbactum, Ceftriaxome + Sulbactum and monotherapy of amikacin showed higher sensitivity to Pseudomonas infections; however, the maximum sensitivity was shown by the Carbapenems.

Conclusion: From the present study, we conclude that urinary tract infection was the most common hospital acquired infection. Also, co-administration of beta -lactamase inhibitors markedly expanded the anti-microbial sensitivity of semi-synthetic penicillins and cephalosporins. The aminoglycoside group of antibiotics - amikacin - demonstrated maximum sensitivity against pseudomonas species. Therefore, use of amikacin should be restricted to severe nosocomial infections, in order to avoid rapid emergence of resistant strains. Periodic susceptibility testing should be carried out over a period of two to three years, to detect the resistance trends. Also, a rational strategy on the limited and prudent use of anti-Pseudomonal agents is urgently required.

Keywords: Antimicrobial susceptibility; Pseudomonas aeruginosa; carbapenem sensitivity; combination antibiotics; disk diffusion technique.

Figure 1a

Antibiotic resistance patterns of P. aeruginosa against penicillin group of antibiotics. Ampicillin, amoxicillin, ticarcillin and piperacillin in combination with sulbactum, clavulanic acid and tazobactum demonstrated significantly higher antibacterial activity (P≤0.001, Chi-square test) against P. aeruginosa when compared to the monotherapy of respective antibiotics

Figure 1b

Antibiotic resistance patterns of P. aeruginosa against cephalosporin group of antibiotics. Cefoperazone, cefotaxime and ceftriaxone in combination with sulbactum demonstrated significantly higher antibacterial activity (P≤0.001, Chi-square test) when compared to monotherapy of respective antibiotics

Figure 1c

Antibiotic resistance patterns of P. aeruginosa against carbapenem group of antibiotics. Imipenem and meropenem demonstrated significantly higher antibacterial activity (P≤0.001, Chi-square test) when compared to aztreonem