Download Salmonella typhimurium

What is emerging infection?

An emerging infectious disease is an
infectious disease whose incidence has
increased in the past 20 years and threatens to
increase in the near future.
 This include diseases caused by a newly
identified microorganism or newly identified
strain of a known microorganism.
 Some examples of emerging infections are
Ebola virus , Lyme disease,
Salmonellosis/Salmonella ,
Shigellosis/Shigella, Dengue Fever.
Multi Drug Resistance…..

Multi-drug resistant organisms are bacteria or
virus that are resistant to a number of antibiotic.

It is a condition enabling a disease-causing organism to
resist distinct drugs or chemicals of a wide variety of
structure and function targeted at eradicating the
organism.
Many different bacteria now exhibit multidrug resistance,
including staphylococci, enterococci, gonococci,
streptococci, salmonella , Mycobacterium tuberculosis.

Cause for Multi-Resistance??




The increase in multi antimicrobial resistant has been
associated with the wide spread use of antimicrobial
agents in food production.
Multi-resistance organisms arise naturally by
spontaneous mutation.
Over usage of antibiotics also leads to the resistance
of bacteria towards antimicrobials.
When the genes for resistance are passed on from one
bacteria to other, then the bacteria will acquire resistance
towards antibiotics.
Image showing the formation of antibiotic resistance gene in
bacteria
•Efflux pumps are transport proteins involved in the extrusion of toxic
substrates from within cells into the external environment.
•Pumps may be specific for one substrate or may transport a range of
structurally dissimilar compounds (including antibiotics); such pumps
can be associated with multiple drug resistance (MDR)
Salmonella Species….

The genus Salmonella contains over 2,000 serospecies and is one of the most important
pathogens in the family Enterobacteriaceae.
 Many types of salmonella species are
responsible for salmonellosis, but S.
typhimurium and S. enteritidis are the two
most commonly found.
 Salmonella causes food borne disease since
salmonella transmits through raw or
contaminated food products.
“Salmonella Typhimurium”
Image showing Salmonella Typhimurium
S.Typhimurium……

Salmonella typhimurium is a leading cause of human
gastroenteritis.

It is a Gram-negative , anaerobic bacteria of the family
Enterobacteriaceae, usually motile with peritrichous (
flagella in all direction)flagella.

S. typhimurium, causes a wide range of infections in
birds and mammals ranging from self limiting
gastroenteritis to severe systemic paratyphoid diseases.

S. typhimurium acts along with S.enteritidis and cause
disease in the environment.
Transmission of salmonella…

Salmonella infections are zoonotic.

Salmonella bacteria can be found in food
products such as raw poultry, eggs, and beef,
and sometimes on unwashed fruit.

The present situation with S. typhimurium is
complicated by the presence of the organism
inside the egg, in the yolk.
Effects!!!!

Initial symptoms are diarrhea, vomiting, fever
and abdominal cramps.

If not treated initially it leads to nausea, loss of
appetite and gastro intestinal infections.

If the salmonella enters the blood stream and
circulates there, it leads to an infection called
bacteremia.
Effects due to drug-resistance…




Chronic stage of salmonellosis leads to
Reiter’s syndrome.
Reiter’s syndrome leads to reactive arthritis,
eye irritation and urinary tract infection.
The symptoms of Reiter’s Syndrome usually
occur between one and three weeks after the
infection.
Arthritis may even lead to spondylitis,
inflammation of the vertebrae in the spinal
column.
Treatment???

Persons with severe diarrhea require rehydration, often with intravenous fluids.
 If the infection spreads to the intestines, the
infection can be treated with Antibiotics.
 The antimicrobials most widely regarded as
optimal for the treatment of salmonellosis in
adults is the group of fluoroquinolones.
 The
earlier drugs
chloramphenicol,ampicillin and amoxicillin
and trimethoprim-sulfamethoxazole are
occasionally used as alternatives.
Test for drug resistance…..
(i) Agar Dilution Method:

This test is done using 80 salmonella strains got from
chicken carcass and giblet samples. These isolated
samples were serotyped with slide agglutination and
then tested for resistance to 23 drugs.

Amikacin ,Amoxicillin and clavulanic acid, Ampicillin,
Apramycin,Carbadox,Ceftiofur,Ceftriaxone,Cephalotin,C
hloramphenicol,Ciprofloxacin,Florfenicol,Gentamicin,Kan
amycin,Nalidixicacid,Neomycin,Nitrofurantoin,Spectinom
ycin,Streptomycin,Sulfisoxazole,Tetracycline,Tobramycin
,Cotrimoxazole,Trimethopri.
(i) Method contd…
Result:



Out of all the 80 strains all the strains were susceptible
to Ciprofloxacin, Nalidixic acid, Ceftiofur, Ceftriaxone,
Cephalotin, Amikacin, Apramycin, Gentamicin,
Neomycin, Tobramycin and Kanamycin.
Fifty one strains were resistant to one or more
antimicrobials i.e. 63.7% were multiple drug resistant.
Less than 21% were resistant to Carbadox, Trimethoprim
and Cotrimoxazole
(ii) In vitro testing method..



The activities of mecillinam and Ampicillin alone and in
combination were evaluated in mice infected with the LT
2 strain of salmonella typhymurium.
Ampicillin in doses of >=0.03 mg and mecillinam in
doses of >= 0.5 mg reduced mortality rates from 77% in
saline treated controls to a range of 0-47% (P<0.05).
The same doses of antibiotics also extended the median
times to death and lowered significantly the means of
splenic bacterial counts.
(ii) Method contd…


When both drugs were combined in doses that were
partially effective or sub inhibitory alone, no synergistic
effects were observed.
These results showed that mecillinam and Ampicillin
given alone were effective in treating S. typhymurium
infection but that combinations of two drugs were not
synergistic in controlling the course of infections.
About PCR Technique….

In molecular biology, the polymerase chain reaction
(PCR) is a technique to amplify a single or few copies of
a piece of DNA across several orders of magnitude,
generating thousands to millions of copies of a particular
DNA sequence.
 In the PCR procedure trace amounts of DNA can be
quickly and repeatedly copied to produce a quantity
sufficient to investigate using conventional laboratory
methods.
 The PCR technique enables early diagnosis of malignant
diseases.
Image of PCR!!!!!
Diagnosis using PCR Technique…




Multiplex PCR assay for Salmonella detection has been
developed.
Six sets of primers were designed to detect the major
Salmonella serotypes and phage types in Spain.
The different amplification profiles obtained allowed us to
detect Salmonella bacteria and to distinguish the
clinically prevalent Salmonella enterica serotypes
Enteritidis, Typhimurium.
Using this method, we could detect a specific band for
DT104 and U302 phage types in Salmonella serotype
Typhimurium.
Vaccination…….

Salmonella is resistant to antibiotics and not to vaccines.
Hence vaccines can be taken to prevent salmonellosis.

A single-dose, oral salmonella typhi vaccine strain has
been sought as a carrier or vector of cloned genes
encoding protective antigens of other pathogens.

Such a hybrid vaccine, administered orally, would
stimulate immune responses both at the mucosal
surface and in the systemic compartment and would
potentially provide protection against multiple pathogens.
Prevention!!!





Do not eat or drink foods containing raw eggs.
Should not drink unpasteurized milk or raw milk.
Under cooked meat or poultry shouldn’t be consumed,
as this meat may carry bacteria.
Frequent and over consumption of antibiotics should
be avoided so that resistance of the pathogen to the
antibiotic can be controlled.
Food prepared for infants must be very hygienic and
bottles must be sterilized before usage, since infants are
easily prone to bacterial infections.
Conclusion!!!!
Control of multi-drug resistant Salmonella
typhimurium DT 104 requires reducing
infection in food animals and lowering the
risk of contamination at all stages in the
food production chain.
 It is required to create an awareness
amoung the public about the multi
resistant pathogen and complications due
to these pathogens.
