Salmonella is a gram-negative bacterium, belongs to the family Enterobacteriaceae.

- The credit of discovery of ‘Salmonella’ goes to Salmon and Smith (1885)

- The most important serotype of Salmonella, S. Typhi, was first observed by Eberth (1880) and Gaffky (1884) and hence was formerly called Eberth-Gaffky bacillus or Eberthella Typhi.

 Salmonella is antigenically complex. The classification and nomenclature of salmonellae have undergone several modifications over the past years. There are several classifications proposed so far.

Clinical Classification

It is the oldest, user friendly classification which is still widely used. It divides salmonellae into two groups:

1. Typhoidal Salmonella: It includes serotypes S. Typhi and S. Paratyphi. They are restricted to human hosts, in whom they cause enteric fever (typhoid/paratyphoid fever)

 2. Non-typhoidal salmonellae or NTS: The remaining serotypes can colonize the intestine of a broad range of animals, including mammals, reptiles, birds and insects. They also infect humans causing food-borne gastroenteritis and septicemia.

Antigenic Classification (Kauffmann–White Scheme)

 The classification within the genus is based on the presence of different somatic (O) and flagellar (H) antigens which can be detected by agglutination with the respective antisera (Table 1).

- Serogroups: Based on O antigen, salmonellae are initially classified into serogroups:

* Earlier, serogroups were named as letters, e.g. A, B, C and so on

* However, as the numbers increased, the serogroups are re-designated as numbers, e.g. 1, 2, 3 and so on

* Currently, there are up to 67 serogroups, each containing group-specific O antigen, for example:

● Serogroup-2 (formerly, serogroup A)—contains group specific O antigen type 2

● Serogroup-4 (formerly, serogroup B)—contains group-specific O antigen type 4

● Serogroup-9 (formerly, serogroup D)—contains group specific O antigen type 9.

- Serotypes: Each serogroup is further differentiated into serotypes, based on the type of flagellar antigens present. Currently, there are more than 2,500 serotypes of salmonellae.

Table1. Kauffmann–White antigenic classification for Salmonella.

Molecular Classification

Based on DNA hybridization studies, the genus Salmonella consists of two species—(1) Salmonella enterica, and (2) S. bongori.

- Within the species S. enterica, there are six subspecies; namely enterica, salamae, arizonae, diarizonae, houtenae and indica

- Each subspecies is further differentiated into serotypes (based on O and H antigens as described in the Kauffmann–White scheme) (Table 1)

- Most of the pathogenic typhoidal and non-typhoidal Salmonella serotypes are placed under species enterica and subspecies enterica.

Nomenclature

Taxonomically, the correct nomenclature of the members of salmonellae is very much complicated, e.g. Salmonella species enterica subspecies enterica serotype Typhi.

However, for routine use a simplified format is followed where only the genus and serotype names are included, for example Salmonella serotype Typhi or in short, S. Typhi.

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قسم الشؤون الفكرية ينظّم برنامجًا تدريبيًّا لعدد من ملاكات المؤسسات الثقافية في ذي قار

إقامة المحاضرة الرابعة من محفل نهج البلاغة في مقام الإمام المهدي (عجل الله فرجه)

للعام التاسع.. المجمع العلمي يطلق 29 ختمة قرآنية رمضانية في النجف الأشرف

قسم الصيانة يجري أعمال الإدامة الدورية لجدران حرم مرقد أبي الفضل العباس (عليه السلام)

المزيد

الآخبار الصحية

مفاجأة.. تحسين القدرة على التحمل لا يعتمد العضلات فقط

المرتفعات والأكسجين.. دراسة "مبشرة" لمرضى السكري

علماء يبتكرون "آلية" تتوقع موعد ظهور أعراض الزهايمر

ماذا يحدث لجسمك عند التوقف عن تناول الخضراوات والفواكه؟

المزيد

الآخبار التكنلوجية

رصد "القرش النائم" في أحد أقسى الأماكن على وجه الأرض

أسماك أعماق البحر تكشف نظاما بصريا يتجاوز "المألوف"

زوكربيرغ أمام القضاء في قضية إدمان المراهقين

"علي بابا" تكشف عن نموذج جديد للذكاء الاصطناعي

المزيد

مواضيع ذات صلة

Infections of the Urinary Tract : Pathogenesis

Infections of the Urinary Tract : Etiologic Agents

Infections of the Sinuses

Pathology of Acromegaly

clinical Features of Hyperprolactinaemia and Prolactinomas

Infections of the Ears : Diseases, Epidemiology, and Etiology of Disease

Encephalitis/Meningoencephalitis

Secondary Forms of Pure Red Cell Aplasia

Pathophysiology of Paroxysmal Nocturnal Hemoglobinuria

Clinical Manifestations of Paroxysmal Nocturnal Hemoglobinuria

Hypothyroidism: Etiology and Treatment

Introduction and History of Paroxysmal Nocturnal Hemoglobinuria