Involvement of Enterobacter cloacae in the mortality of the fish, Mugil cephalus.
OBJECTIVE
To identify the causative agent of the mortality in the fish, Mugil cephalus, in Muttukadu lagoon.


RESULTS
An enteric bacterium from the kidneys of moribund fish M. cephalus, was isolated and identified as Enterobacter cloacae (MK). Mugil cephalus was experimentally infected by this isolate and was re-isolated from the kidneys of the moribund fish. Enterobacter cloacae isolates from the lagoon water (MW1, MW2 and reference strain ATCC 13047) and the reference strain were not able to induce similar pathogenesis. The putative factor imparting pathogenicity to the MK isolate was identified as a cationic molecule, which migrated towards the cathode on agarose gel electrophoresis.


CONCLUSIONS
The Ent. cloacae (MK) isolate harbouring a cationic factor was the causative agent for the mortality of M. cephalus, found in Muttukadu lagoon.


CONCLUSIONS
This study reveals that human enteric bacteria MK which is considered as nonpathogenic to fish, may become pathogenic to fish when it harbours this cationic factor. This cationic factor is found to be pathogenic to the fish M. cephalus leading to mortality. It was also found to be pathogenic to mice. Therefore, the shuttling of Ent. cloacae, harbouring cationic factor, between human and fish may be of human health importance.
Sekar
V Thillai
VT
Aquatic Animal Health Division, Central Institute of Brackishwater Aquaculture, Chennai, India.
Santiago
T C
TC
Vijayan
K K
KK
Alavandi
S V
SV
Raj
V Stalin
VS
Rajan
J J S
JJ
Sanjuktha
M
M
Kalaimani
N
N
D000818:Animals; D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D016972:Enterobacter cloacae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004756:Enterobacteriaceae Infections / Q000382:microbiology / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D005393:Fish Diseases / Q000382:microbiology* / Q000401:mortality / Q000473:pathology; D007194:India; D007684:Kidney Tubules / Q000473:pathology; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D023701:Smegmamorpha / Q000382:microbiology*
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S