The incidence of sepsis is a growing problem worldwide with a high mortality rate.  K- capsule antigens are becoming more dangerous than before. The purpose of the study was to categorize the capsules virulence factors, as well as to find a safe and empirical antibiotic treatment for sepsis infection, and to determine if the existence of ESBL producing bacteria have increased exponentially in recent decades. A total of 101 isolates were collected for a period of 5 years, of which blood isolates (n=38) were collected at Uppsala university hospital and feces isolates from healthy mothers and their infants (n=63) at Cunghi hospital, China. Isolates were serotyped with agglutination test, using N. meningitides B / Ecoli K1 against K1 capsule antigen, and phage test, using K1, K5 and K13 bacteriophage to identify the corresponding E. coli K antigen. Results showed that K1- capsule antigen could be identified in 42% (16/38) of the blood-isolated bacterial strains, compared with 11% (7/63) in fecal-isolated bacterial strains, while K5- capsule antigen was serotyped in 5% (2/38) and 19% (12/63), respectively. In contrast, the K13 capsule antigen was not found in blood-isolated bacterial strains and was serotyped only in 4% (3/63) of the fecal-isolated bacterial strains. Overall, the investigated E.coli  K capsular antigens were identified in 47% (18/38, non -typeable n=20) of the blood-isolated cultures compared with 35% ( 22/36, non-typeable=41) in fecal-isolated cultures..