4. Antimicrobial resistance( AMR) is a global health threat And animal is one of the
contributing source.
Shiga toxin-producing Escherichia coli (STEC) has emerged as significant foodborne
pathogens.
Shiga toxin–producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of
bloody diarrhea and hemolytic-uremic syndrome (HUS).
The ability of STEC strains to cause human disease is due to the production of Shiga
toxins.
5. Cattle are the major reservoir of STEC, and humans acquire STEC infections through
ingestion of cross-contaminated food of cattle origin.
Non-O157 STEC sero-groups O26, O45, O103, O111, O121, O145 are frequently
associated with severe illness and outbreaks in humans.
These six serotypes account for about 75% of all STEC infections in human.
6. E.Coli O157 ingested
HUSResolution
Non bloody diarrhea, abdominal cramps
Bloody diarrhea
3-4 days
1-2 days80%
92% 8%
5-6 days
Sequence of events in E.coli O157:H infection
7. Non STEC E.Coli O157 ingested
HUSResolution
Non bloody diarrhea, abdominal cramps
Bloody diarrhea
3-4 days
1-2 days40%
98% rare
5-6 days
Sequence of events in Non O157 STEC infection
8. Cycle of event in spread of STEC (STEC Cattle and contaminated cycle)
9. Infection begins once Stx bind to the cell-surface receptor on the endothelial
cells.
Thereafter, the catalytic A-subunit is translocate into the cell cytosol,
resulting in the inhibition of protein synthesis after inactivation of 60S
ribosomal subunit of the eukaryotic cell.
STEC infections require a low infectious dose (<50 bacterial cells), and the
incubation period, prior to the onset of diarrhea, ranges between 2 and 12
days
Mechanism action of Shiga toxin
12. Objectives of the study
To determinate
the prevalence
of food born
pathogen which
is contaminated
by cattle feces
Phylogenetic
analysis of
selected gene
(stx-1 and stx-2
gene)
Characterize and
identify the
bacterial isolates
by
morphologically
on selective
media and stx
gene sequencing
To study the
prevalence and
distribution of
stx(1) and stx(2)
gene in E. coli
O157:H7 and
non-O157:H7
strains isolated
from cattle in
khustia
Bangladesh.
Antibiogram
profile of
identified
bacterial
isolates
14. Sample collection
(Cow feces)
Isolation
of bacteria
Identification of bacteria
Morphological
identification
Molecular
identification
Selective media based
identification i.e. EMB
and SMAC
General media based
identification: i.e. NA
Biochemical
identification
PCR
Gene sequencing
Antibiotic sensitivity
assay
Flowchart
Serological
identification
15. Sample collection
Source of samples: Sheikh para bazer, Anandonagor, Horipur agriculture farm
in Kushtia, Bangladesh
Number of samples: Total 30~50 samples of cattle feces
Collected Sample: 08
Research: Laboratory of Microbiology, Department of Biotechnology and
Genetic Engineering, Islamic University, Kushtia, Bangladesh
16. Isolation process of bacteria:
Approximately 1~10 g of each fecal sample was mixed in 9~90 ml of Trypticase
soya broth (TSB) with 20 mg/L novobiocine and incubated for 16–18 h at 37 °C.
This was streaked out onto sorbitol MacConkey agar (SMAC) supplemented
with 1 mg/L potassium tellurite and incubated for 18–24 h at 37 °C.
The morphologically distinguished colonies were observed, counted and
recorded.
The remaining colonies on the selective and differential media were also
observed by streaking in selective and differential media i.e. Eosin methylene
blue (EMB) and Rainbow Agar media.
~
17. Morphological identification:
Bacterial morphology deals with
• Size,
• Shape, and
• Arrangement of bacterial cells.
Molecular identification:
Selected bacterial isolates were identified using specific gene (stx-1 and stx-2)
sequencing.
19. 1. Sample collection: Total 30~50 samples of cattle feces. Collected sample 08
2. Isolation of bacteria: On going
3. Identification of bacteria: Not yet down
Result and Discussion
23. STEC O157 and non-O157 represents a serious threat to public health worldwide.
The potential for large-scale outbreaks and widespread prevalence in animal sources
have necessitated the development and evaluation of rapid, sensitive, and specific
methods for detection and surveillance for this pathogen.
This study help to identify the antibiotic resistance strains of STEC which could be
serious health problem to human .
