Example Of The Most Likely Gram Negative ROD Bacterium Responsible To Cause These Manifestations In Katie Is Salmonella Species. Case Study

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QUESTION 1:

According to Marineli, Tsoucalas, Karamanou and Androutsos (2013), Karl Liebermeister theorized that this condition is caused by a bacterium long before the isolation and identification of Salmonella. William Budd, Bristol based doctor, experimented to prove the presence of a particular toxin present in water contaminated with human excreta in 1873. The genus name “Salmonella” is coined after Daniel Elmer Salmon who was an America based veterinary pathologist and administrator of USDA program. Mary Mallon, an Irish cook caused typhoid outbreak and the first case of healthy carrier of typhoid was published in 1907. The outbreak affected nearly 3000 inhabitants of New York and possibly because of Mary Mallon.
According to Levinson (2014), Salmonella are rod shaped bacteria and gram negative. They do not ferment lactose but have the ability to produce H2S, which aids in laboratory identification. The virulence factors of Salmonella are Cell wall O antigen, Flagellar H antigen and Capsular Vi antigen. Salmonella is divided further based on O antigen into groups A to I. H antigen has two subtypes; phase 1 and phase 2. There is only expression and synthesis of one H subtype at a time.Vi antigen gives special antiphagocytic property peculiarly to Salmonella Typhi. It is also helpful in the serotyping of S.Typhi. Salmonella species is broadly classified clinically into typhoidal and non-typhoidal species. S.Typhi and S.Paratyphi are typhoidal or typhoid causing species while serotypes of S.enterica and S.Choleraesuis are non-typhoidal or diarrhea and metastatic infection causing species. The toxin involved in the pathogenesis of typhoid fever is called as endotoxin.

QUESTION 2:

The significant features in the history and lab results of Katie suggestive of typhoid are
The onset of fever and diarrhea is sudden.
Day care student
3 days old visit to a zoo

Exposure to the animal/excreta

Bad hygiene
Presence of blood in stool
Presence of gram negative rods
Katie is a 5 year old kid who recently visited a zoo. Salmonella species is transmitted through contaminated food or water and through exposure to animal feces. Katie played with animals and fed them without precaution. Moreover, she did not wash her hands properly and ate food with contaminated hands. This suggests food contamination.
The presence of blood in the stool also suggests Salmonella infection. Although, dysentery is also a feature of other diseases as well but, there was no associated abdominal pain or tenderness. Katie had also experienced fever suggesting bacterial infection.
The stool detailed culture report shows heavy growth of gram negative rods and blood. The most common gram negative rod causing enteric fever or infection in the United States is Salmonella species. Based on all these findings and the history, a safe diagnosis of typhoid caused by Salmonella species can be made.

QUESTION 3:

Typhoid fever commonly affects young individuals and children predominantly in areas with poor sanitation and overcrowding. Few parts of Asia and Africa have high typhoid incidence. In Oceania and Latin America, incidence rate is 10 to 100 cases per 100,000 persons each year.
Humans are solely the reservoir for typhoid infections therefore, travel history to an endemic area or contact history with a typhoid carrier is very crucial. In the United States, 200 to 300 cases are registered each year and 80% of these individuals have a travel history to a high risk area. Most of the travelers are not immunized despite strong recommendation. Its outbreak in the United States is foodborne but unlike other parts of the world, typhoid infection is not drug resistant.
The risk factors among various Salmonella species may differ according to a particular type but infection occurs mainly either because of food consumption from outside vendor or even from household consumption. Household infection is justified by use of shared utensils, a typhoid carrier at home, lack of proper hygiene, lack of soap or detergents and improper toilet facilities.
In pediatric population, typhoid fever can lead to pneumonia and febrile convulsions. However, children less than 5years of age are protected against intestinal perforation caused by inflamed Peyer’s patches. It can cause few neurologic symptoms as well which includes headache, sleep disturbance, psychosis, myelitis, rigid paralysis, and meningitis. Severely affected individuals may develop typhoid encephalopathy with delirium. (Hohmann, 2013, uptodate.com)

QUESTION 4:

According to Papadakis and McPhee (2015), treatment for typhoid fever consists of specific measures and treatment for carriers. The specific treatment focusses on treating the primary victim presenting with the diagnosis of typhoid fever. The antibiotics used for treating typhoid are ampicillin, chloramphenicol, azithromycin, trimethoprim-sulfamethoxazole (TMP-SMX) and third generation cephalosporins. All of these drugs are effective only in drug sensitive strains. They can be administered orally or intravenously both. But, in resistant strains, a fluoroquinolone should be added like ciprofloxacin (750mg B.D) or levofloxacin (500mg O.D) for 5-7 days in uncomplicated and 7-10 days in complicated case of typhoid fever. Ceftriaxone should be given intravenously with the dose of 2g for a week. Further, if the strain is still resistant, rely on the culture and sensitivity report to prescribe proper anti-microbial.
For the treatment of carriers, ampicillin, TMP-SMX or chloramphenicol should be used and a fluoroquinolne like ciprofloxacin can be added in the dose of 750mg twice a day for a period of one month. Cholecystectomy is also warranted in eradicating carrier states.
The mortality rate is not so high and is only as nominal as 2%. The prognosis becomes worse with increasing age and complications. 15 % of the cases may relapse and a residual carrier state still exists even with anti-microbials.

References

Hohmann, E. (2013, September 26). Epidemiology, microbiology, clinical manifestations, and diagnosis of typhoid fever. Retrieved March 20, 2015, from http://www.uptodate.com/contents/epidemiology-microbiology-clinical-manifestations-and-diagnosis-of-typhoid-fever
Levinson, W. (2014). Chapter 18: Gram-Negative Rods Related to the Enteric Tract. In Review of Medical Microbiology and Immunology (13th ed., p. 349). Philadelphia, PA: McGraw-Hill Education/Medical.
Marineli, F., Tsoucalas, G., Karamanou, M., & Androutsos, G. (2013). Mary Mallon (1869-1938) and the History of Typhoid Fever. Annals of Gastroenterology, 26(2), 132-134.
Papadakis, M., & McPhee, S. (2015). Bacterial & Chlamydial Infections. In Current Medical Diagnosis & Treatment 2015 (54th ed., p. 1437). New York: McGraw-Hill Education/Medical.