RT Journal Article SR Electronic(1) A1 Einarsdottir, Thorbjorg A1 Gunnarsson, Eggert A1 Sigurdardottir, Olof G. A1 Jorundsson, Einar A1 Fridriksdottir, Vala A1 Thorarinsdottir, Gudridur E. A1 Hjartardottir, SigridurYR 2016 T1 Variability of Pasteurella multocida isolated from Icelandic sheep and detection of the toxA gene JF Journal of Medical Microbiology, VO 65 IS 9 SP 897 OP 904 DO https://doi.org/10.1099/jmm.0.000306 PB Microbiology Society, SN 1473-5644, AB Pasteurella multocida can be part of the upper respiratory flora of animals, but under conditions of stress or immunocompromisation, the bacteria can cause severe respiratory symptoms. In this study, we compared 10 P. multocida isolates from Icelandic sheep with respiratory symptoms and 19 isolates from apparently healthy abattoir sheep. We examined capsule type, genetic variability and the presence of the toxA gene in the two groups. Surprisingly, we found that all ovine P. multocida isolates examined in this study carried the toxA gene, which markedly differs from what has been published from other studies. Interestingly, all isolates from abattoir animals were capsule type D, whilst bacteria isolated from animals with clinical respiratory symptoms had capsule type A, D or F. Examination of seven housekeeping genes indicated that the clinical respiratory isolates were significantly more heterogeneous than the abattoir isolates (P<0.05, two-tailed Mann–Whitney U test). The results suggest that there may be at least two groups of P. multocida in sheep – a genetically homogeneous group that resides in the respiratory tract and a genetically heterogeneous group that is the predominant cause of disease., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.000306