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BackgroundThe Mycoplasma mycoides cluster consists of five species or subspecies that are ruminant pathogens. One subspecies, Mycoplasma mycoides subspecies mycoides Small Colony (MmmSC), is the causative agent of contagious bovine pleuropneumonia. Its very close relative, Mycoplasma mycoides subsp. capri (Mmc), is a more ubiquitous pathogen in small ruminants causing mastitis, arthritis, keratitis, pneumonia and septicaemia and is also found as saprophyte in the ear canal. To understand the genetics underlying these phenotypic differences, we compared the MmmSC PG1 type strain genome, which was already available, with the genome of an Mmc field strain (95010) that was sequenced in this study. We also compared the 95010 genome with the recently published genome of another Mmc strain (GM12) to evaluate Mmc strain diversity.ResultsThe MmmSC PG1 genome is 1,212 kbp and that of Mmc 95010 is ca. 58 kbp shorter. Most of the sequences present in PG1 but not 95010 are highly repeated Insertion Sequences (three types of IS) and large duplicated DNA fragments. The 95010 genome contains five types of IS, present in fewer copies than in PG1, and two copies of an integrative conjugative element. These mobile genetic elements have played a key role in genome plasticity, leading to inversions of large DNA fragments. Comparison of the two genomes suggested a marked decay of the PG1 genome that seems to be correlated with a greater number of IS. The repertoire of gene families encoding surface proteins is smaller in PG1. Several genes involved in polysaccharide metabolism and protein degradation are also absent from, or degraded in, PG1.ConclusionsThe genome of MmmSC PG1 is larger than that of Mmc 95010, its very close relative, but has less coding capacity. This is the result of large genetic rearrangements due to mobile elements that have also led to marked gene decay. This is consistent with a non-adaptative genomic complexity theory, allowing duplications or pseudogenes to be maintained in the absence of adaptive selection that would lead to purifying selection and genome streamlining over longer evolutionary times. These findings also suggest that MmmSC only recently adapted to its bovine host.

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The present study was undertaken to determine the prevalence and distribution of Salmonella from apparently healthy slaughtered camels in Eastern Ethiopia. A total of 714 samples (faeces, mesenteric, lymph nodes, spleen, liver, abdominal and diaphragmatic muscles) from 119 slaughtered camels were analysed. Salmonellae were detected from 116 (16.2%) of the 714 samples examined. Eighteen (15.1%) faeces, 19 (15.9%) mesenteric lymph nodes, 14 (11.8%) livers and 17 (14.3%) spleen samples (n = 119 for each) were positive for Salmonella. Salmonellae were found in 20.1% of the abdominal and diaphragmatic muscles. A total of sixteen different serotypes were identified of which Salmonella saintpaul (38.8%) and S. braenderup (22.4%) were the most prevalent followed by S. muenchen (8.6%), S. kottbus (6.0%) and S. havana (5.2%). Other serotypes, including S. typhimurium, S. heidelberg and S. enteritidis were also detected from Ethiopian camels.

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Du lait de quartier (n = 828) a été prélevé chez 207 femelles dromadaires (Camelus dromedarius) en lactation, provenant de troupeaux du Borana, au sud-ouest de l’Ethiopie, et élevées de manière traditionnelle. L’objectif de l’étude a été de décrire la prévalence des mammites et certaines étiologies bactériennes chez le dromadaire. Le California mastitis test (Cmt) a été utilisé comme test de dépistage et des examens bactériologiques ont été effectués pour identifier les agents pathogènes impliqués dans les mammites. La numération cellulaire somatique du lait de quartier des chamelles a également été déterminée. Vingt-cinq quartiers (12,1 p. 100) ont été trouvés non productifs parmi les 828 examinés. Un pourcentage de correspondance de 100 p. 100 a été trouvé pour les échantillons classés 3+ et 2+ avec Cmt, alors qu’un pourcentage de correspondance de 35, 71 et 85 p. 100 a été relevé pour ceux classés respectivement 0, traces et 1+ avec Cmt. Une association significative a été observée dans le lait de quartier des chamelles entre les classements positifs obtenus avec Cmt et la présence d’agents pathogènes principaux. La numération cellulaire somatique a été comprise entre 3 x 105 et 1,5 x 107 leucocytes par millilitre de lait. Les moyennes du comptage cellulaire ont montré une évolution numérique positive en fonction des classes croissantes du Cmt avec Anova. Parmi les femelles en lactation examinées, quatre (1,9 p. 100) cas cliniques de mammites ont été détectés. Des bactéries pathogènes ont été présentes dans 171 échantillons (74 p. 100) de lait de quartier examiné positif avec Cmt. Parmi les principaux agents pathogènes isolés ont été trouvées des espèces de Staphylococcus, Streptococcus, Micrococcus, Corynebacterium et Bacillus, ainsi que Actinomyces pyogenes, Escherichia coli et Pasteurella haemolytica.

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