Salmonella
·
Salmonella species are motile
gram-negative rods, and grow both aerobically and anaerobically at an optimum
temperature of 37°C (range 7 to 48°C), and at a pH between 4 and 8. They are
readily killed by heat (71.7°C for 15 seconds) and acid, but are resistant to
both freezing and drying, especially in the presence of proteins.
·
Food poisoning (Salmonella
enterocolitis) can be caused by all salmonellae except S. typhi which causes typhoid or enteric fever. Commonest species
involved include S. typhimurium, S.
enteritidis, S. hadar, S. heidelberg, S. agona, S. arizonae, S. chameleon, S.
java, S. javiana, S. marinum, S. oranienburg, S. muenchen, S. paratyphi B, S.
virchow, S. indiana, and S. anatum.
·
Eggs: Even unbroken, unsoiled eggs
can be contaminated. Eating such eggs raw or undercooked can result in
infection
o
Food products containing raw eggs
are also capable of producing the illness—hollandaise sauce, eggnog, chocolate
mousse, raw egg-based milk shakes, Caesar salads, and home-made ice cream.
o
It is recommended that eggs should
be consumed within 3 weeks after being laid, and must be stored at temperatures
below 8° C after purchase. milk poses a real risk of being infected with
salmonel- losis. Even pasteurised milk may not be 100% protective. Outbreaks of
salmonella infections may be associated with multiple drug-resistant strains.
·
Salmonella has also been detected in
various sesame seed products, including sesame paste and halvah (a mixture of sesame seed paste and acidified heated glucose
syrup).
·
Household pets: Chicks, turtles,
iguanas, and other reptiles are known to harbour salmonellae, and can transmit
the micro-organisms to household contacts. Cats may be faecal carriers of
Salmonella without displaying clinical signs. The incidence ranges from 1 to
18% of cats.
·
Enterotoxin.
· Penetration of intestinal wall and multiplication by the bacilli.
·
About 12 to 36 hours, but can be as
short as 3 hours.
·
Vomiting, crampy abdominal pain,
diarrhoea. Stools are loose, slimy, foul-smelling, and greenish in colour. They
often turn blood-stained. These symptoms may be absent in children, who may
present only with abdominal pain and nausea, which could be confused with acute
appendicitis.
·
Fever.
·
Headache, malaise, myalgia.
·
Toxic megacolon and intussusception
have been reported with Salmonella typhimurium.
·
Focal nephritis has been reported in
some cases.
·
The illness usually subsides in 2 to
4 days, but occasion- ally becomes prolonged and dysentery-like, with passage
of mucus and pus in the stools.
·
The carrier state is more common
among females and elderly patients, and it may persist for months to years.
·
The gall bladder is the usual focus
of infection in the carrier state.
·
Complications:
o
Meningitis
o
Septicaemia
o
Reiter’s syndrome**
o
Death.
·
Isolation of Salmonella by
o Analysis
of suspect food item
o Culture
of stool and blood.
·
Check WBC for leucocytosis or
leukopenia.
■■ Patients with
significant toxicity, dehydration, electrolyte disturbances, or a history of
poor compliance should be admitted for IV fluid therapy, and occasional
antibiotic therapy.
■■ As far as possible,
antibiotic treatment must be resorted to only in the following cases:
bacteraemia, AIDS patients, elderly, infants, and individuals with sickle cell
disease. The antibiotic of choice is chloramphenicol. Fluoroquinolones,
ampicillin, ceftriaxone, and trimethoprim-sulfamethoxazole are also effective.
■■Supportive measures.
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