ST 315
E. coli has been reported earlier in urosepsis, intra-abdominal infections and primary sepsis in medical cases [
16]. Therefore, comparative analysis [with NC_017646 (NMEC), NC_008253 (UPEC), NC_017631 (UPEC), NC_007946 (UPEC)] and exploration of virulence genes in AK-1 was performed which resulted in identification of assorted virulence factors. These are commonly associated with ExPEC isolates [
26] as shown in Table
2.
E. coli type III secretion system 2 (ETT2) identified in AK-1 has been previously reported in
E. coli strains in partial or complete form [
27]. ETT2 is associated with virulence regulation in some ExPEC strains and pathogenicity in septicemic
E. coli [
28]. Pathogenicity island (PAI), type 6 secretion system was identified in AK-1 [
29]. Multiple PAI, invested in fimbriae and adhesions expression, were observed in AK-1 strain which are described as (i) Type 1 fimbriae is common in UPEC, causes infection in mucous surfaces by inducing adhesion and virulence [
30], (ii) Chaperone usher (CU) fimbriae clusters
yad and
sfm provide additional adhesion to the host [
31], (iii) Mat (meningitis associated and temperature regulated) fimbria or
E. coli common pilus (ECP) responsible for colonisation and adherence in host [
32], (iv) Curli fibres binds to hosts matrix and plasma protein, and is reported to cause haemagglutination, fibronectin binding and formation of proteolytically active plasmin which aids in bacterial diffusion through tissue disintegration [
30], (v) ExPEC specific FdeC (
factor a
dherence
E.
coli) responsible for bacterial fitness and colonization in UTI [
33].
Type 1 fimbriae NSBV01000003 (15138–21501) sfm fimbriae NSBV01000011 (7740–14015) yad fimbriae NSBV01000005 (66168–72121) MAT(ECP) fimbriae NSBV01000007 (119869–126709) FdeC NSBV01000007 (106372–110622) Curli NSBV01000004 (93069–97942) | ChuA NSBV01000028 (31777–40728) Enterobactin NSBV01000021 (27676–46582) Aerobactin NSBV01000005 (59212–52929) | HlyA NSBV01000011 (54096–55271) HlyE NSBV01000026 (46866–47777) | TypeIII secretion system (ETT2) NSBV01000002 (15607–31153) TypeVI secretion system NSBV01000032 (5165–28659) | ColV NSBV01000002 (84476–84964) ibeB NSBV01000021 (57575–58957) K1capsule NSBV01000002 (150300–158286) ompA NSBV01000004 (166414–167466) |
ExPECs cope up with low iron availability by secreting siderophores which retrieves sequestered iron from host proteins [
36]. AK-1 was identified to harbour aerobactin, enterobactin and chuA siderophores. Proectins/invasins like ibeB, ompA and K1 capsule have been reported in invasion of brain microvasular endothelial cells [
37].