Application of biochemical fingerprinting to the investigation of clonal groups of Salmonella of serotype Havana.

Abstract

A computerised typing method based on biochemical fingerprinting was used to investigate biochemical phenotypes (BPTs) among 70 strains of Salmonella of serotype Havana isolated from human cases of gastroenteritis in Iran and other parts of the world. A total of 16 BPTs comprising five common and 11 single phenotypes was identified. The most frequently found BPT contained 24 isolates from Iran and nine from other countries. Three common BPTs with two, seven and 15 isolates were found among Iranian strains only and one common BPT with two isolates was found among non-Iranian strains only. Antibiotic-resistance patterns and virulence properties of strains from these common BPTs suggested that they might be unique clones. Forty-two Iranian isolates shared multi-resistance to between three and seven antibiotics. In contrast, none of the isolates from other countries was resistant to antibiotics. Furthermore, 43 Iranian isolates showed mannose-resistant adhesion to HeLa cells and 24 of them possessed an aerobactin-mediated iron-uptake system, whereas none of the isolates from other countries possessed any of these virulence properties. These findings suggest that four unique clones of Salmonella Havana with different BPTs and virulence properties are common in Iran; two particular clones were responsible for a majority of Havana infections there. However, the most prevalent BPT found among Iranian strains was also common in strains from other countries. It is concluded that biochemical fingerprinting, as used in this study, is a reliable method for identifying clonal groups of Havana strains. The method is reproducible, easy to perform and can be used alone, or in combination with other typing methods, in epidemiological studies of serotype Havana.