Multidrug-resistance (MDR) bacteria have emerged as a public health threat in the modern era. Extended spectrum β-lactamase has emerged as the most successful resistance mechanism among the Enterobacteriaceae family. ESBLs are often mediated by blaTEM and blaCTX-M genes. The study evaluated the molecular characteristics of ESBL-producing P. mirabilis isolates from the Klang River in order to find the therapeutic options for ESBL infections. There appears to be a high prevalence of CTX-M and TEM genes among P. mirabilis strains in the Klang River. Therefore, rapid identification should be conducted for proper infection control and antibiotic usage. Molecular techniques serve as a useful tool in the understanding of MDR bacteria resistance.