Frequency of extended-spectrum beta lactamase positive and multidrug resistance pattern in Gram-negative urinary isolates, Semnan, Iran

Introduction and objective: Monitoring of the antimicrobial susceptibilities provides information about pathogenic organisms isolated from patients, and assists in choosing the most appropriate empirical antimicrobial therapy. This study tried to determine frequency of extended spectrum beta lactamase (ESBL) positive and multidrug resistance pattern in Gram-negative uropathogenic bacteria. Materials and methods: In this study, 310 Gram-negative uropathogen were investigated. Combined disk test was used as a screening test for ESBL production. Disk diffusion method was performed for antibiotic susceptibility testing. Results: Isolated bacteria were as follow: 226(72.9%) Escherichia coli, 76(24.5%) Klebsiella pneumoniae, 3(1%) Citrobacter spp. 2(0.6 %) Proteus mirabilis and 3(1 %) Pseudomonas spp. ESBL production was observed in 88(28.4%) of all isolates, 29.2% of E. coli isolates and 28.9% of K. pneumonia. The most and least resistance were seen in the case of ampicillin (98.4%) and ceftazidime (24.2%), respectively. Resistance to six antibiotics or more was seen in 104 isolates (33.5%). Conclusion: In the present study, relatively high frequency of ESBL production and multidrug resistance were seen in uropathogens. To avoid treatment failure and choose either empirical or direct therapy by physicians, antimicrobial susceptibility testing and ESBL production monitoring are recommended in patients with urinary tract infection (UTI).