The aim of this study was to determine the prevalence of fecal carriage of extended-spectrum beta-lactamase (ESBL)producing bacteria, enzyme types, and risk factors affecting colonization. Materials and methods:A total of 576 stool samples from outpatients were examined between October 2012 and May 2013. Screening was done with selective EMB plates. ESBL were detected by double-disk synergy and confirmed agar strip gradient methods. Enzyme types were determined by PCR. Results:The prevalence of fecal carriage was found as 30% (173 of 576). Recent use of antibiotics, hospitalization and surgical operation, diabetes, crowded household populations, and old age were associated with higher carriage rates. Of the ESBL-producing bacteria, 87.5% were positive for bla CTX-M genes. Of the bla CTX-M gene-positive isolates, 95.2% were positive for bla CTX-M-1 genes; among these, 82.2% were positive for bla CTX-M-3 and 67.7% were positive for bla CTX-M-15 genes while 62.5% isolates were positive for both bla CTX-M-3 and bla CTX-M-15 genes Conclusions: A high rate (30%) of fecal carriage of ESBL bacteria was found in an adult population. The predominant beta-lactamase enzyme types were CTX-M-3 and CTX-M-15.