Distribution of SPV genes, plasmid profiles and pulsotypes of Salmonella enteritidis isolates of animal and human origins in selected locations of Zimbabwe

Agness Farai Nhidza¹*, Bamusi Saidi², Pious Vengesai Makaya², Pride Kanyoka²,

Idah Sithole-Niang³ and Dexter Savadye⁴

¹Biomedical Research and Training Institute, Box CY 1753, Causeway, Harare, Zimbabwe.

²Central Veterinary Laboratory, Veterinary diagnostics and research branch,

Department of Veterinary and Technical Services, Harare, Zimbabwe.

³University of Zimbabwe, Biochemistry Department, Harare, Zimbabwe.

⁴Scientific and Industrial Research and Development Centre (SIRDC), Harare, Zimbabwe.

*Corresponding author. E-mail: nhidzaagness@gmail.com. Tel: +263-4-797049, +263-4-703522. Fax: +263-4-735033.

Accepted 27 April, 2012

Abstract

A total of 49 Salmonella enteritidis isolates identified by culture and biochemical tests were confirmed using multiplex polymerase chain reaction (PCR). The isolates were grouped into two, those with Salmonella plasmid virulence (spv) gene and those without the spv gene. Plasmid and pulsed field gel electrophoresis (PFGE) analysis were performed on both groups. Of the 49 S. enteritidis isolates identified, 39 possessed a spv gene. Moreover, of the 39 isolates possessing the spv genes, 32 were from animals and 7 from humans. Those isolates without the spv genes comprised of 5 isolates from humans and 5 from animals. Plasmid analysis discriminated the isolates with the spv genes into 11 profiles and isolates without spv gene into 3 profiles. PFGE discriminated S. enteritidis isolates into 10 pulsotypes (9 from animals and 1 from the human outbreak strains). There was no correlation between the pulsotypes or plasmid profiles with the geographical location of isolate. However, there was a link between strain type and source of isolate. The study was performed to characterize S. enteritidis strains using molecular typing techniques and determine their geographical distribution in Zimbabwe. The information obtained can give background information for further studies on Salmonella epidemiology in Zimbabwe.

Key words: spv, Salmonella enteritidis, pulsotypes, plasmid profiles, multiplex polymerase chain reaction (PCR), pulsed field gel electrophoresis (PFGE).