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Background: The production of extended-spectrum β-lactamases (ESBLs) confer resistance to the commonly used beta-lactam antimicrobials and ESBL-producing bacteria render treatment difficulty in human and veterinary medicine. ESBL-producing bacteria have emerged in livestock in recent years, which may raise concerns regarding possible transfer of such bacteria through the food chain. The swine industry is important in Taiwan, but investigations regarding the status of ESBL in swine are limited. Results: We collected 275 fecal swab samples from piglets with diarrhea in 16 swine farms located in central and southern Taiwan from January to December 2015 and screened them for ESBL-producing Escherichia coli. ESBL producers were confirmed phenotypically by combination disc test and genotypically by polymerase chain reaction and DNA sequencing. The occurrence rate of ESBL-producing E. coli was 19.7% (54 of 275), and all were obtained in swine farms located in southern Taiwan. blaCTX-M-1-group and blaCTX-M-9-group were the two blaCTX-M groups found. blaCTX-M-55 (34 of 54; 63.0%) and blaCTX-M-15 (16 of 54; 29.6%), which belong to the blaCTX-M-1-group, were the two major bla gene types, whereas blaCTX-M-65 was the only type found in the blaCTX-M-9 group. Twenty-seven strains contained blaTEM-1, and the other 27 strains contained blaTEM-116. One strain found in Pingtung harbored three bla genes: blaTEM-116, blaCTX-M-55, and blaCTX-M-65. ESBL-producing E. coli exhibited a multidrug-resistant phenotype, and multilocus sequence typing revealed that the ST10 clonal complexes, including ST10, 167, 44, and 617 accounted for 35% (19 of 54) of these strains. Conclusions: ESBL-producing E. coli from piglets with diarrhea were isolated from swine farms located in southern Taiwan. The most commonly detected bla were blaCTX-M-15 and blaCTX-M-55. The ST10 clonal complexes comprised most of our ESBL-producing E. coli strains. Fecal shedding from swine may contaminate the environment, resulting in public health concerns; thus, continued surveillance of ESBL is essential in swine and in other food animals. [ABSTRACT FROM AUTHOR]