**4.1 Adhesins**

For UPEC to colonize and cause infection, it needs to be equipped with some adhesive molecules which will promote attachment to the host cell surface. Adherence to host cell is regarded as the crucial step for colonization because in normal instances regular urinary flow does not permit colonization of the bacteria to the urinary tract. The adhesive factors found in UPEC are known to be adhesins which exists either in the form of filamentous surface organelles called pili or fimbriae or as non-filamentous proteins in the outer membrane.
