Salmonella Infections

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Salmonella Infections
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Salmonella Infections

• Salmonellas are a major cause of food borne
  diseases (Food Poisoning). Members of this genus
  also.
• Cause enteric fever (typhoid and parathyroid
  fevers). These are only human pathogens.
• They are members of the family enterobacteriaceae
  sharing all their characters. They are non
  Lactose fermenters and they are motile.

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Antigenic Structures Two Main Types of Antigens
Are Available.

• Heat stable polysaccharide which is part of the
  cell wall called Somatic or O antigen.
• Flagella antigens or H antigen
• Two phase are available.
• Phase I and Phase II
• A third antigen or the envelope or Vi antigen
• According to these antigens the members of the
  Salmonella are divided into serogroup from A T.

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(Salmonella Infections .. Cont.)

• Clinically the Salmonellas are divided into two
  main divisions
• Enteric fever or (typhoid and paratyphoid fever)
  causing Salmonellas.
• These are
• Salmonella typhi
• Salmonella paratyphi A
• Salmonella paratyphi B
• Salmonella paratyphi C
• The clinical features of infection by these
  organisms is fever, and generalized symptoms of
  systemic infection. There is also blood stream
  infection and localization in certain organs in
  the body. Besides these there are also
  gastrointestinal symptoms. Antibiotic treatment
  is always advised for these infections.

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(Two Main Divisions of Salmonella.. Cont..)

• Food borne diseases or food poisoning
  Salmonellas.
• They are also called gastroenteritis causing
  Salmonellas. Infection by these Salmonella is
  mostly confined to the gastrointestinal tract
  presenting with abdominal pain, vomiting and
  diarrhoea. They rarely cause systemic
  infections. However, they can cause systemic or
  generalized infection in immunocompromised
  patient, the very young or the very old patients.
  Antibiotic treatment is not advised for these
  infection unless there is systemic infection.
  The treatment is only fluid and electrolytes
  replacement if there is severe diarrhoea and / Or
  vomiting.

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Typhoid And Paratyphoid Fever (Enteric Fever)

• It is one of the causes of pyrexia of unknown
  origin syndrome (P.U.O. Or F.U.O.)
• Causative agents
• 1. Salmonella typhi 2. Salmonella paratyphi
  A
• 3. Salmonella paratyphi B 4. Salmonella
  paratyphi C
• Methods of Transmission
• By faecal - oral route through contaminated food
  items or water by faecal material from patients
  or carriers.

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(TYPHOID AND PARATYPHOID FEVER.. Cont.)

• PATHOGENESIS (See the diagram).
• Infective dose is 102 organisms. This dose is
  affected by host factors. E.g. Lower stomach
  acidity
• When the organisms are ingested they overcome the
  gastric acidity and reach the small intestine and
  start multiplying and attachment to microville
  and enter the cells and further multiply in the
  Peyers mesentric lymphnodes ? thoracic duct ?
  blood ? RES ? blood ? gall bladder,
  intestines ? faeces.

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Pathogenesis Of Typhoid Fever

• S. TYPHI
  SMALL INTESTINE
• BILE
• GALL BLADDER
  M.L. NODES
• THORACIC DUCT
• BACTEREMIA
  BLOOD
• R.E.S.
• MULTIPLICATION PHASE DURING
• INCUBATION PERIOD
• BLOOD (SEPTICAEMIA) ONSET OF SYMPTOMS

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(TYPHOID AND PARATYPHOID FEVER.. Cont.)

• Clinical Features
• Incubation period is 10-14 days after which the
  patients starts to have fever which is the main
  presenting symptom accompanied by other symptoms
  of a generalized infection e.g. General
  malaise, fever, headache, sweating and later on
  gastrointestinal.
• Symptoms like
• diarrhoea
• abdominal pain
• vomiting

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(CLINICAL FEATURESCONT..)

• If not treated the intestinal infection can be
  severe enough to cause perforations. The patient
  may also have general central nervous system
  involvement appearing as delirium, and maybe
  coma.
• In fair skin people some skin rash may appear
  called ROSE SPOTS.
• The organisms live intracellularly in the
  macrophages of the reticuloendothelial system
  i.e. The liver, spleen, liver, and lymph nodes.

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(TYPHOID AND PARATYPHOID FEVER.. Cont.)

• Being an intracellular organism this leads to
• Immunity is mainly cell mediated
• Antibodies protects only against the bacteraemia
  phase so they are not protective, although their
  presence is diagnostic.
• Antibiotic used for treatment should be those
  which enter and work inside the cell.
• Relapse is common.

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Diagnosis Of Enteric Fever

• Clinical history of travel outside and eating
  in public places. Common in people retrieving
  from Pakistan, Sudan, and Egypt.
• Clinical Examination
• Temperature as stepladder appearance.
• Rose spots
• Hepatosplenomegaly
• Rarely enlarged Lymph nodes

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(TREATMENT OF ENTERIC FEVER.. Cont..)

• Clinical Features
• Culture of
• Fever
• Malaise
• Headache
• G.I.T
• C.N.S Features
• Skin rash (Rose spots)
• Acquired By
• Food, water, orally
• Large spleen, liver

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(DIAGNOSIS OF ENTERIC FEVER...Cont..)

• Laboratory Diagnosis
• Culture
• Specimen blood / bone marrow 1st week
• faeces 2nd week
• urine 3rd week
• Faeces should be culture on
• Bile salt containing media e.g. DCA or
  Selenite F broth medium Look for non-lactose
  fermenters then do biochemical tests and
  serological tests.
• Serological test on patient serum
• People who get infected by Salmonella typhi and
  paratyphi A, B, and C develop antibodies against
  these organisms. These ntibodies can be
  detected by agglutination test in the Widal Test
  looking for rising titre of these antibodies.
• General more low WBC, low Hb, high ESR

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Complications of Enteric Fever

• Relapse if treatment is not given for required
  period of 2 weeks.
• Perforation of the last part of the small
  intestine, not commonly seen these days why?
  Because of early diagnosis and treatment.
• Carrier state this is not an uncommon
  complication. It is mainly in the gall bladder
  although Salmonella paratyphi b can be in the
  tubules of the kidney.
• It is more common in females.
• It is dangerous in these patients who are food
  handlers as they can transmit it to other people.
• It is also difficult to treat as it may need
  prolonged treatment.

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Treatment Of Enteric Fever

• Replace fluid if there is dehydration.
• Antibiotic are very important in the treatment
  of enteric fever.
• Chloramphenicol, the best drug but can not always
  be used as it has rare severe bone marrow
  complications.
• Ampicillin
• Cotrimoxazole
• Nowadays and mainly from Indian Subcontinent
  some patients are infected with Salmonella strain
  resistant to these three first line enteric fever
  drugs.
• These are usually treated by
• Ciprofloxacin
• Ceftriaxone

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(TREATMENT OF ENTERIC FEVER.. Cont..)

• Treatment of Carriers
• Ampicillin or Cotrimoxazole
• May need to surgically remove the gall bladder.
• Prevention
• Good water supply
• Good hygiene
• Vaccination for people going to endemic areas.

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(TREATMENT OF ENTERIC FEVER.. Cont..)

• Diagnosis Usually positive in
• Culture of
• Blood 1st Week
• Stools 2nd Week
• Urine 3rd Week
• Serology
• Widal 2nd -3rd Week
• C.I.E.
• Patient serum diluted
• titre Anti O
• Anti H Good water supply
• Culture on DCA.
• Salenite broth
• N.L.F
• Biochemical Serological tests

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Food poisoning

• Zonosis

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(TREATMENT OF ENTERIC FEVER.. Cont..)

• Food Posioning, gastroenteritis Or Food borne
  disease causing Salmonellas
• They cause
• Gaseroenteritis
• Food borne diseases (85 of cases)
• Food posioning
• There are more than 2000 species
• The infective dose is high 106 - 108
• E.g.
• S. typhimurium
• S. dublin
• S.london
• S.khartoum
• Now given only number for names.

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(TREATMENT OF ENTERIC FEVER.. Cont..)

• They could be zoonotic from all types of animals
  mainly chickens.
• They could be obtained from human food handlers
• They can causes systemic disease in
• Immunocompromised patient e.g. Leukemics, AIDS
• Very young less than 4 years
• Very old more than 70 years
• Treatment
• Replacement of water (fluid) and electrolytes in
  case of severe diarrhoea
• Antibiotic not indicated if there is no systemic
  infection.

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Shigella

• Bacillary dysentery
• Shigellosis

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Characteristics

• Enterobacteriacae
• Gram-negative bacilli
• Non-motile
• Non-lactose fermenter ( NLF )
• H2S negative
• Capsule (K-antigen)
• O somatic antigen

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Species

• Sh. dysenteriae . 10 serotypes (most
  serious)
• Sh . flexineri 6 serotypes (developing
  nations)
• Sh. bodyii 15 - serotypes
• Sh. sonei 1 - serotype (United states)

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Bacillary dysentery

• Acute bacterial infection of the intestine
  (colon)
• Caused by all species.
• Varies in severity .
• Major cause of diarrhial disease and mortality.
• Developed countries.
• (POOR HYGIENE , NUTRITION)
• (CONTAMINATED FOOD , WATER)

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Epidemiology

• Human
• Fecal-oral route.
• ( water , food , feces , flies )
• Person-person contact.
• Childhood.
• ID 10 - 100 organisms.
• High infectivity.
• IP - 1 4 days.
• Source cases and carriers.
• Daycare centers, mental institutions, travel and
  homosexuals.

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Clinical picture

• Fever
• Bloody diarrhea
• Abdominal cramps
• Tenesmus
• Mucus and pus
• Convulsions
• Mild infection watery diarrhea
• Bacteremia rare
• REITER,S syndrome .
• Hemolytic uremic syndrome .

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Clinical picture

• Mild illness rehydration.
• short ( 48 72 h)
• SH . Sonei
• Bacillary dysentery
• ANTIMICROBIAL THERAPY ( SHORTEN THE DURATION ,
  PREVENT SPREAD)
• AMPICILLIN (PLASMID RESISTANCE)
• COTRIMOXAZOLE (RES.)
• CIPROFLOXACIN
• CEFTRIAXONE

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Prevention

• Supply of pure water
• Personal hygiene ( hands )
• Sewage disposal
• Food hygiene
• Insect control ( flies )
• Vaccine ( oral )