Study of Antibiotic Susceptibility Pattern and Frequency of Extended Spectrum β-lactamases Genes TEM and SHV in Urinary Tract Isolates of Escherichia coli and Klebsiella pneumoniae in Tabriz

Urinary tract infection (UTI) is one of the most common types of hu man infections and Escherichia coli and Klebsiella pneumonia are the main causes of urinary tract infection among the gram negative bacteria. The prevalence of extended-spectrum β-lactamases (ESBLs) among these bacteria and hence resistant strains to β-lactam antibiotics have increased in recent decades. Several types of extended-spectrum β-lactamases, such as TEM, SHV and CTX-M have been identified, which are prominently present in the strains of E. coli and K. pneumoniae. The objective of this study was to determine the prevalence of TEM and SHV genes in E. coli and K. pneumoniae isolates of urinary tract infections by using phenotypic and molecular (PCR) tech niques in microbiology laboratory at medical school of Tabriz Islamic Azad University.

In this cross-sectional descriptive study, 50 isolates of E. coli and 50 isolates of K. pneumoniae collected from uri nary tract infections from out-patients in Tabriz. Antibiotic sensitivity patterns of isolates were stu died against 14 antibiotics by disk diffusion test (Kirby Bauer) and also confirmatory tests were performed using combined antibiotic tests. Finally TEM and SHV genes were investigated using molecular methods (PCR).

Twenty five isolates (25%) out of 100 bacterial isolates were identified as ESBL-producing isolates of which 13 isolates (26%) were E. coli and 12 isolates (24%) were K. pneumoniae. The TEM and SHV genes were detected in 2% and 4% of E.coli and 0% and 2% of K. pneumoniae isolates, respectively.

The presence of these genes among our isolates confirmed ESBL genes in these medically important bacteria leading to resistance against β-lac tam antibiotics which are routinely used in their treatments. The low frequency of the studied genes could be because of the source of our isolates from out-patients which are not generally exposed to antibiotics