Salmonella Infections

  Salmonellas are a major cause of food borne diseases (Food Poisoning could acquired a zoonosis). 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.

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 3. 3.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.

(Salmonella Infections. Cont….) Clinically the Salmonellas are divided into two main divisions: a. a.Enteric fever or (typhoid and paratyphoid fever) causing Salmonellas. These are: 1. 1.Salmonella typhi 2. 2.Salmonella paratyphi A 3. 3.Salmonella paratyphi B 4. 4.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.

(Two Main Divisions of Salmonella.. Cont…..) b) b)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 patients, 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.

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: 1. 1.By faecal - oral route through contaminated food items or water by faecal material from patients or carriers.

(Typhoid And Paratyphoid Fever.. Cont….) Pathogenesis: (See the diagram).   Infective dose is 10 2 organisms. This dose is affected by host factors. E.g. Low 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 Peyer’s mesentric lymphnodes  thoracic duct  blood  RES  blood  gall bladder, intestines  faeces.

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 KIDNEY GALLBLADDER & INTESTINES FAECES INFECTING DOSE 100 ORGANISMS

Clinical Features:   Incubation period is 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: a) a)diarrhoea b) b)abdominal pain c) c)vomiting (Typhoid And Paratyphoid Fever.. Cont….)

(Clinical Features…Cont…..)   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.

Being an intracellular organism this leads to: a) a)Immunity is mainly cell mediated b) b)Antibodies protects only against the bacteraemia phase so they are not protective, although their presence is diagnostic. c) c)Antibiotic used for treatment should be those which enter and work inside the cell. d) d)Relapse is common. (Typhoid And Paratyphoid Fever.. Cont….)

Diagnosis Of Enteric Fever A. A.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

(Treatment Of Enteric Fever.. Cont…..) Clinical Features: 1. 1.Fever 2. 2.Malaise 3. 3.Headache 4. 4.G.I.T 5. 5.C.N.S Features 6. 6.Skin rash (Rose spots) Acquired By: Food, water, orally 7. 7.Large spleen, liver

(Diagnosis Of Enteric Fever...Cont…..) B. B.Laboratory Diagnosis: a) a)Culture:Positive in: Specimen:blood / bone marrow1 st week faeces2 nd week urine3 rd week Faeces should be cultured 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. b) b)Serological test on patient serum People who get infected by Salmonella typhi and paratyphi A, B, and C develop antibodies against these organisms. These antibodies can be detected by agglutination test in the Widal Test looking for rising titre of these antibodies. c) c)General: more low WBC, low Hb, high ESR

Complications of Enteric Fever a) a)Relapse if treatment is not given for required period of 2 weeks. b) b)Perforation of the last part of the small intestine, not commonly seen these days why? Because of early diagnosis and treatment. c) c)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.

Treatment Of Enteric Fever a) a)Replace fluid if there is dehydration. b) b)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: a) a)Ciprofloxacin b) b)Ceftriaxone

(Treatment Of Enteric Fever.. Cont…..) Treatment of Carriers: a) a)Ampicillin or Cotrimoxazole b) b)May need to surgically remove the gall bladder. Prevention: a) a)Good water supply b) b)Good hygiene c) c)Vaccination for people going to endemic areas.

(Treatment Of Enteric Fever.. Cont…..) Diagnosis: Usually positive in: Culture of i. i.Blood 1 st Week ii. ii.Stools 2 nd Week iii. iii.Urine 3 rd Week 1. 1.Serology a. a.Widal 2 nd -3 rd Week b. b.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

(Treatment Of Enteric Fever.. Cont…..)   Food Poisoning, gastroenteritis or Food borne disease causing Salmonellas They cause   Gaseroenteritis   Food borne diseases (85% of cases)   Food poisoning   There are more than 2000 species   The infective dose is high e.g.   S. typhimurium   S. dublin   S.london   S.khartoum Now given only number for names.

(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: 1. 1.Replacement of water (fluid) and electrolytes in case of severe diarrhoea 2. 2.Antibiotic not indicated if there is no systemic infection.