Dubravka S. Milanov1*, Milan D. Đilas2, Jelena М. Babić1, Bojana Z. Prunić1, Maja Ј. Velhner1 "/> Dubravka S. Milanov1*, Milan D. Đilas2, Jelena М. Babić1, Bojana Z. Prunić1, Maja Ј. Velhner1 "/>

Food & Feed Research


Volume 45, Issue 2
Salmonella-like bacteria, cheese
TOOLS Creative Commons License
Dubravka S. Milanov1*, Milan D. Đilas2, Jelena М. Babić1, Bojana Z. Prunić1, Maja Ј. Velhner1
1Scientific Veterinary Institute ‘Novi Sad’, Rumenački put 20, 21000 Novi Sad, Serbia
2Institute of Public Health of Vojvodina, Futoška 121, Novi Sad, Serbia


Salmonella-like bacteria, such as certain species of the Citrobacter genus are sometimes isolated from food and feed. By testing their biochemical and, partially, serological characteristics (according to the regulations given in the ISO 6579-1:2017 Standard) it is impossible to completely reject their affiliation to the Salmonella genus. In addition to this, the food microbiology laboratories usually lack diagnostic tools and procedures for precise identification of these isolates to the species level. Thus, it is considered useful to describe the identification of Citrobacter youngae species using MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry). Besides differential diagnostic criteria for distinguishing between Salmonella spp. and Citrobacter youngae, in this communication the relevant data on Citrobacter spp., the emerging opportunistic pathogenic member of Enterobacteriaceae family were presented.

Download full article PDF


  1. Arens, S., Verhaegen, J., Verbist, L. (1996). Differentiation and susceptibility of Citrobacter isolates from patients in a university hospital. Clinical Microbiology and Infection, 3 (1), 53-57.
  2. Biswas, S., Rolan, J.M. (2013). Use of MALDI-TOF mass spectrometry for identification of bacteria that are difficult to culture. Journal of Microbiological Methods, 92, 14–24.
  3. Brenner, D.J., Grimont, P.A., Steigerwalt, A.G., Fanning, G.R., Ageron, E., Riddle, C.F. (1993). Classification of citrobacteria by DNA hybridization: designation of Citrobacter farmeri sp. nov., Citrobacter youngae sp. nov., Citro-bacter braakii sp. nov., Citrobacter werkmanii sp. nov., Citrobacter sedlakii sp. nov., and three unnamed Citrobacter genomospecies. Interna-tional Journal of Systematic Bacteriology43 (4), 645-658.
  4. Baylis, C., Uyttendaele, M., Joosten, H., Da-vies, A. (2011). The Enterobacteriaceae and their significance to the food industry. ILSI Europe Report Studies, ILSI International Life Sciences Institute, ILSI Europe a.i.s.b.l., Belgium.
  5. (http://ilsi.eu/wp-content/uploads/sites/3/2016/06/EP-Enterobacteriaceae.pdf).
  6. Clermont, D., Motreff, L., Passet, V., Fernan-dez, J.C., Bizet, C., Brisse, S. (2015). Multilo-cus sequence analysis of the genus Citrobacter and description of Citrobacter pasteurii nov. International Journal of Systematic and Evo-lutionaryMicrobiology, 65, 1486–1490.
  7. Dekker, J.P., Branda, J.A. (2011). MALDI-TOF Mass Spectrometry in the clinical microbiology laboratory. Clinical Microbiology Newsletter, 33 (12), 87-93.
  8. Doran, T.I. (1998). The role of Citrobacter in clinical disease of children: review. Clinical In-fectious Diseases, 28, 384–94.
  9. Duman M, Saticioglua, I.B., Buyukekiza, A.G., Baltab, F., Altuna S. (2017). Molecular charac-terization and antimicrobial resistance profile of atypical Citrobacter gillenii and Citrobacter isolated from diseased rainbow trout (On-corhynchus mykiss). Journal of Global Anti-microbial Resistance, 10, 136-142.
  10. ISO 6579-1:2017 (2017). Microbiology of the food chain – Horizontal method for the detec-tion, enumeration and serotyping of Salmonella – Part 1: Detection of Salmonella
  11. Janda, M.J., Abbott, S.L., Cheung K.W., Hanson, D.F. (1994). Biochemical identification of Citrobacteria in the clinical laboratory. Jour-nal of Clinical Microbiology, 32 (8), 1850-1854.
  12. Kolínská, R., Španelová, P., Drevínek, M., Hra-bák, J., Žemličková, H. (2015). Species iden-tification of strains belonging to genus Citro-bacter using the biochemical method and MALDI-TOF mass spectrometry. Folia Micro-biologica, 60, 53-59.
  13. Kwak, H.L., Han, S.K., Park, S., Park, S.H., Shim, J.Y., Oh, M., Ricke, S.C., Kim, H.Y. (2015). Development of a rapid and accurate identification method for Citrobacter species isolated from pork products using a Matrix-Assisted Laser-Desorption Ionization Time-of-Flight Mass Spectrofotometry (MALDI-Tof MS). Journal of Microbiology and
  14. Biotechnology, 25 (9), 1537-1541.
  15. Murray, P.R. (2012). What is new in clinical microbiology-Microbial identification by MALDI-TOF Mass Spectrometry. The Journal of Mole-cular Diagnostics, 14 (5), 419-423.
  16. Samonis, G., Karageorgopoulos, D.E., Kofte-ridis, D.P., Matthaiou, D.K., Sidiropoulou, V., Maraki, S., Falagas, M.E. (2009). Citrobacter infections in a general hospital: characteristics and outcomes. European Journal of Clinical Microbiology & Infectious Diseases,28 (1), 61–68.
  17. Thurm, V., Gericke, B. (1994). Identification of infant food as a vehicle in a nosocomial outbreak of Citrobacter freundii: epidemiological subtyping by allozyme, whole-cell protein and antibiotic resistance. Journal of Applied Bacte-riology, 76, 553-558.
  18. Tschape, H.,Prager, R., Streckel, W., Fruth, A., Tietze, E., Böhme, G. (1995). Verotoxino-genic Citrobacter freundii associated with se-vere gastroenteritis and cases of haemolytic uraemic syndrome in a nursery school: green butter as the infection source. Epidemiology and Infection, 114, 441-450.