Epidemiology and Infection



REVIEW

Host adapted serotypes of Salmonella enterica


S. UZZAU a1, D. J. BROWN a2, T. WALLIS a3, S. RUBINO a1, G. LEORI a4, S. BERNARD a5, J. CASADESÚS a6, D. J. PLATT a7c1 and J. E. OLSEN a2
a1 Dipartimento di Scienze Biomediche, Università di Sassari, 07100 Sassari, Italy
a2 Department of Veterinary Microbiology, The Royal Veterinary & Agricultural University, DK-1870 Frederiksberg C., Denmark
a3 Institute of Animal Health, Compton, Berkshire RG20 7NN, England
a4 Istituto Zooprofilattico Sperimentale della Sardegna, 07100 Sassari, Italy
a5 INRA, Centre de Recherche de Tours-Nouzilly, 37380 Nouzilly, France
a6 Departamento de Genética, Universidad de Sevilla, 41012 Sevilla, Spain
a7 University Department of Microbiology, Royal Infirmary, Glasgow G4 0SF, Scotland

Abstract

Salmonella constitutes a genus of zoonotic bacteria of worldwide economic and health importance. The current view of salmonella taxonomy assigns the members of this genus to two species: S. enterica and S. bongori. S. enterica itself is divided into six subspecies, enterica, salamae, arizonae, diarizonae, indica, and houtenae, also known as subspecies I, II, IIIa, IIIb, IV, and VI, respectively [1]. Members of Salmonella enterica subspecies enterica are mainly associated with warm-blooded vertebrates and are usually transmitted by ingestion of food or water contaminated by infected faeces. The pathogenicity of most of the distinct serotypes remains undefined, and even within the most common serotypes, many questions remain to be answered regarding the interactions between the organism and the infected host.

Salmonellosis manifests itself in three major forms: enteritis, septicaemia, and abortion, each of which may be present singly or in combination, depending on both the serotype and the host involved. Although currently over 2300 serovars of Salmonella are recognized, only about 50 serotypes are isolated in any significant numbers as human or animal pathogens [2, 3] and they all belong to subspecies enterica. Of these, most cause acute gastroenteritis characterized by a short incubation period and a severe systemic disease in man or animals, characterized by septicaemia, fever and/or abortion, and such serotypes are often associated with one or few host species [4–6].

It is the intention of this review to present a summary of current knowledge of these host-adapted serotypes of S. enterica. The taxonomic relationships between the serotypes will be discussed together with a comparison of the pathology and pathogenesis of the disease that they cause in their natural host(s). Since much of our knowledge on salmonellosis is based on the results of work on Typhimurium, this serotype will often be used as the baseline in discussion. It is hoped that an appreciation of the differences that exist in the way these serotypes interact with the host will lead to a greater understanding of the complex host–parasite relationship that characterizes salmonella infections.

(Accepted April 10 2000)


Correspondence:
c1 Author for correspondence.


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