Typhoid or enteric fever is a clinical syndrome characterized by constitutional and gastro intestinal symptoms ,head ache. Typhoid fever is a bacterial infection of the intestinal tract and occasionally the bloodstream. Typhoid is caused by Salmonella enterica serovar typhi (Salmonella typhi) These waterborne gram negative aerobes are transmitted by consumption of contaminated food or drink.
Salmonella enterica (formerly Salmonella choleraesuis) is a rod- shaped flagellated facultative anaerobic ,gram negative bacterium. Kingdom : eubacteria Family : Enterobacteriaciea Genus : Salmonella Species : S. Enterica Salmonella enterica has 6 subspecies and each subspecies that differ byantigenic specificity. Secreted proteins are of major importance for the pathogenesis of infectious diseases caused by Salmonella enterica.
Antigens: located in the cell capsule• H (flagellar antigen).• O (Somatic or cell wall antigen).• Vi (polysaccharide virulence ) Endotoxin Resistance:• Lives for 2-3 weeks in water.• 1-2 months in stool.• Dies out quickly in summer Resistance to drying and cooling S.enterica serotype typhi Member of family Enterobacteriaciea
Ingestion of the bacteria via contaminated food or water. About 3%-5% of patients become carriers of the bacteria after the acute illness. These chronic carriers may have no symptoms. Flies
Salmonella Typhi P survives the acidity of the stomach A invades the Peyer’s Patches of the intestinal wall T macrophages (Peyer’s Patches) H the bacteria is within the macrophages and survives O Gbacteria spreads via the lymphatics while inside the macrophages Eaccess to Reticuloendothelial system, liver, spleen, gallbladder and N bone marrow E First week: elevation of the body temperature Second week: abdominal pain, spleen enlargement and rosespots S Third week: necrosis of the Peyer’s Patches Ileads to perforation, bleeding and, if left untreated, death…… S
Poor appetite Malaise Cough Sore throat Headaches Generalized aches and pains Fever ascends in step wise fashion after 7 to 10 days reaches plateau. Sustained fever as high as 103 F-104 F (39 C-40 C) Lethargy Diarrhea. Chest congestion develops in many patients, abdominal pain, distention and discomfort are common. About 10% of patients have recurrent symptoms (relapse) after feeling better for one to two weeks. Spleenomegaly Relative bradycardia Rash(rose spots) appear during 2nd weak of disease. The individual spot, found on the trunk, is a pink papule 2-3mm in diameter that fades on pressure. It disappears in 2-3 days
Stage One: Stage Two: A slowly rising Continuing high fever temperature Extremely distended Relative bradycardia abdomen malaise (discomfort or uneasiness), headache Considerable weight loss and cough. Bradycardia continues In ¼ of cases, epistaxis Delirium is frequent, (acute hemorrhage from frequently calm and the nostril) can occur. sometimes agitated.Stage Three: Stage Four: A number of complications can occur: Defervescence (very Intestinal hemorrhage due to bleeding high fever) Intestinal perforation commences that Encephalitis (inflammation of the brain) continues into the Fever is still very high fourth week. Dehydration occurs and increases delirium Lies motionless with eyes half-opened
WBC count is decreased Leukocytopenia(specially eosinophilic leukocytopenia).Blood culture: Identification ofBacteremia occurs early Salmonellain the disease •Sub cultures are doneBlood Cultures are after overnight incubationpositive in at 37 centigrade ,and•1st week in 90% subcultures are done on•2nd week in 75% MacConkeys agar•3rd week in 60% Subcultures are repeated•4th week and later in 25% upto 10 days after further incubation.
The bone marrow culture •Urine and stool cultures• You may have this test if you have • A stool sample is collected in a an unexplained fever clean container and placed under conditions that allow bacteria or• Bone marrow culture is an other organisms to grow. • The type of infection is identified examination of the soft, fatty tissue by noting the appearance of the growth, by performing chemical tests found inside certain bones. This on the stool sample, and by looking at tissue, called bone marrow, the sample under a microscope. produces blood cells.• Doctor removes a small sample of fluid bone marrow through a needle.
The duodenal string test Involves swallowing a string to obtain a sample from the upper part of the small intestine You swallow a string with a weighted gelatin capsule on the end. Four hours later it is pulled back out. Any bile, blood, or mucus attached to the string is examined under the microscope for cells and parasites . Culture bile is useful for the diagnosis of carriers. Rose spots: Not used routinely
WIDAL TESTINTRODUCTION:Enteric fever specific agglutinins (antibodies) are detected in patients after 15 days offever. BCG vaccinated patient’s serum may show elevated titre of all three ‘H’agglutinins. Stained salmonella antigens are used to detect and identify specificantibodies in serum samples from patients suffering from enteric fever.PRINCIPLE:Bacterial suspension which carry antigen will agglutinate on exposure to antibodies tosalmonella organisms.SAMPLE :Fresh seurm is preferred. In case of any delay performing the test, serum should bestored at 20 - 80 C. REAGENTS:1. Antigen suspension, S. typhi O.2. Antigen suspension, S. typhi H.3. Antigen suspension, S. paratyphi ‘AH’.4. Antigen suspension, S. paratyphi ‘BH’.5. Polyspecific positive cotrol6. Glass Slides with 6 reaction circles andMixing sticks.
PROCEDURE:SLIDE TESTobserve for agglutination macroscopically within one minute.
SEMI QUANTITATIVE METHOD : •Pipette one drop of isotonic saline into the first reaction circle and then place 5, 10, 20, 40, 80 ul of the test sample on the remaining circles. • Add to each reaction circle, a drop of the antigen which showed agglutination with the test sample in the screening method.
STANDARD TUBE TEST METHOD1. Take 3sets of 5 test tubes and label them 1 to 5 for O, H, AH and BHantibody detection.2. Pipette into the tube No.1 of all sets 1.9 ml of isotonic saline.3. To each of the remaining tubes (2 to 5) add 1.0 ml of isotonic saline.4. To the tube No.1 tube in each row add 0.1 ml of the serum sample to betested and mix well.
•Transfer 1.0 ml of the diluted serum from tubeno.1 to tube no.2 and mix well.•Transfer 1.0 ml of the diluted sample from tubeno.2 to tube no.3 and mix well. Continue thisserial dilution till tube no.4 in each set.•Discard 1.0 ml of the diluted serum from tubeNo.4 of each set.•Tube No.5 in all the sets, serves as a salinecontrol. Now the dilution of the serum sampleachieved in each set is as follows:Tube No. : 1 2 3 4 5 (control)Dilutions 1:20 1:40 1:80 1:160 1:320•To all the tubes (1 to 5) of each set add one dropof the respective WIDALTEST antigensuspension (O, H, AH and BH) from the reagentvials and mix well•Incubate at 370 C overnight(18 hours)
INTERPRETATION OF RESULTS:SLIDE TEST METHOD•Agglutination is a positive test result and if the positive reactionis observed with 20 ul of test sample, it indicates presence ofclinically significant levels of the corresponding antibody in thepatient serum.•No agglutination is a negative test result and indicates absenceof clinically significant levels of the corresponding antibody inthe patient serum.QUANTITATIVE METHOD•The titre of the patient serum using Widal test antigensuspensions is the highest dilution of the serum sample thatgives a visible agglutination.•The sample which shows the titre of 1:80 or more should beconsidered as clinically significant.
Etiologic and special treatment1.Quinolones:it’s highly against S.typhi penetrate well into macrophages,and achievehigh concentrations in the bowel and bile lumens•Norfloxacin (0.1～0.2mg tid～qid/10～14 days).•Ofloxacin (0.2 mg tid 10～14days).•ciprofloxacin (0.25 mg tid) caution: not in children and pregnant2.Chloramphenicol:For cases without multiresistant S.typhi.Children in dose of 50～60mg/kg/per day.adult 1.5～2g/day. tid.Unable to take oral medication, the same dosage given intravenously
3.Cephalosporines:Cefoperazone and Ceftazidime. 2～4g/day .10~14 days.Chronic carrier:•Ofloxacin 0.2 bid or ciprofloxacin 0.5 bid, 4～6 weeks.•Ampicillin 3～6g/day tid plus probenecid 1～1.5g/day. 4～6 weeks.•Cholecystitis may require cholecystectomy. Adequate waste disposal and protection of food and water supplies from contamination are important public health measures to prevent typhoid fever. Carriers can’t work as food handlers.
Immunization is not always effective but should be considered for household contacts of a typhoid carrier, for travellers to endemic areas and during epidemic outbreaks. A multiple dose oral live-attenuated Ty21a vaccine is supplied as enteric coated capsules. The capsules must be refrigerated and taken with cool liquids atleast 1 hour before meals. Boosters for every 5 years. This vaccine is not recommended for infants,children less than 6 years and immunosuppressed patients. A single dose Vi capsular polysaccharide(Vi CPS) vaccine is available for parenteral use. Boosters for every 2 years. This vaccine is not recommended for infants younger than 2 years. Both the vaccines are of equal efficacy but oral vaccine causes fewer side effects.
•MICROBIOLOGY by MICHAEL J.PELCZAR,JR. ,E.C.S.CHAN, NOEL R.KRIEG 5th ed •APPLIED MICROBIOLOGY by VINITHA KALE , KISHORE BHUSARI 2nd ed•MICROBIOLOGY by PRESCOTT, HARLEY 7th ed• Cruickshank, R(1962) Medical Microbiology, 12th Ed, P:4003.•www.medscape.com•www.giantmicrobes.com•www.kindnessofstrangerstravel.com•www.sabin.org•www.immunize.org