Evaluation of Antimicrobial Susceptibility of Gram Negative Organisms by Minimum Inhibitory Concentration Method in Bandar Abbas, South of Iran

Abstract

Background: Antibiotic-resistant pathogens are problem in many geographic areas. The selection of appropriate antibiotics to treat Gram-negative bacteremia may be life-saving. The aim of this study was to evaluate the incidence of decreased antibiotic susceptibility among aerobic gram-negative bacilli isolated from hospitalized patients of Bandar Abbas general hospital.
Methods: Consecutive specimens collected on clinical indications from hospitalized patients were cultured. The minimum inhibitory concentrations (MICs) of antimicrobial agents were determined by the agar dilution method according to the National Committee for Clinical Laboratory Standards (NCCLS) guidelines.
Results: In this study 494 positive samples during one year were evaluated. The most common site of isolation was urinary system. The most frequently isolated organisms were E.coli (%47.3), Kelebsiella pneumonia (%19.9) and Pseudomonas aeruginosa (%16.2). Resistance to ceftriaxone, ceftazidime and cefepime was more than %50. MIC results revealed that E.coli was sensitive to amikacin, ciprofloxacin and meropenem more than %75; whereas sensitivity to ceftriaxone, ceftazidime and cefepime wasless than %30. Klebsiella showed sensitivity to amikacin %77.1; however sensitivity to ceftriaxone, ceftazidime and cefepime less than %25. In addition, sensitivity of Pseudomonas aeruginosa to amikacin, ciprofloxacin and imipenem was more than %65; while sensitivity to ceftriaxone, ceftazidime and cefepime was %25 or less.
Conclusions: The high incidence of reduced antibiotic susceptibility among gramnegative bacteria in this hospital suggests that more effective strategies are needed to control the selection and spread of resistant organisms.