African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5211

Full Length Research Paper

Identification of three related genera, Salmonella, Citrobacter and Proteus using API 20E, 16S-23S rDNA intergenic transcribed spacer fingerprinting and 16S rDNA sequencing

  Yousra Turki1*, Ines Mehri1, Amel Khessairi1, Kaouther Agrebi2, Abdennaceur Hassen1 and Hadda Ouzari2
  1Laboratoire Traitement et Recyclage des Eaux, Centre de Recherche et des Technologies des Eaux (C.E.R.T.E), Borj Cédria, 8020 Soliman, Tunisie. 2Laboratoire Microorganisme et Biomolécules Actives, Département de Biologie, Faculté des Sciences de Tunis, Campus Universitaire, 2092, Tunis, Tunisie.
Email: [email protected]

  •  Accepted: 05 July 2013
  •  Published: 19 July 2013



A total of 176 presumptive Salmonella strains isolated from different sources (food, environment, veterinary, and human) were analyzed by API 20E, serotyping, ITSF/ITSR-PCR and MINf/MINr-PCR. On the other hand, the 16S-23S rRNA intergenic transcribed spacer region was used to aid in their identification. Test results were confirmed by 16S rRNA sequencing. Of 176 suspected S. enterica isolates, API20E identified 105 (59.6%) as S. enterica, 42 (24%) as Citrobacter and 29 (16.4%) as Proteus. A total of 11 serotypes were found among 102 out of 105 Salmonella isolates. The remaining isolates were classified as untypeable by serotyping. When ITSF/ITSR-PCR and MINf/MINr-PCR were used, 101 out of 105 Salmonella isolates tested generated PCR products.Amplification of the spacer region between 16S-23S rRNA gene allowed discrimination of genera and facilitated species identification. Sequencing of 16S rRNA gene has identified 4 different species in proteus genus (P. mirabilis, P. penneriP. vulgaris, and P. hausseri), 3 different species in Citrobacter genus (Citrobacter freundiiCitrobacter braakii, andCitrobacter youngae), and Salmonella enterica sub sp. enterica for all Salmonella isolates.The four suspect Salmonella isolates were definitively classified in Citrobacter genus. In conclusion, this study has demonstrated that API20E, serotyping associated toSalmonella specific PCR are accurate methods for S. enterica detection. In addition, PCR amplification of the 16S-23S spacer region was suitable tool for identification of bacteria at genera and species level.


Key words: Salmonella, API 20E, serotyping, MINf/MINr-PCR, ITSF/ITSR-PCR, 16S-23S intergenic spacer regions (ITS)-PCR, 16S rRNA.