Persistent Gastric Colonization with Burkholderia pseudomallei and Dissemination from the Gastrointestinal Tract following Mucosal Inoculation of Mice

Melioidosis is a disease of humans caused by opportunistic infection with the soil and water bacterium Burkholderia pseudomallei. Melioidosis can manifest as an acute, overwhelming infection or as a chronic, recurrent infection. At present, it is not clear where B. pseudomallei resides in the mammalian host during the chronic, recurrent phase of infection. To address this question, we developed a mouse low-dose mucosal challenge model of chronic B. pseudomallei infection and investigated sites of bacterial persistence over 60 days. Sensitive culture techniques and selective media were used to quantitate bacterial burden in major organs, including the gastrointestinal (GI) tract. We found that the GI tract was the primary site of bacterial persistence during the chronic infection phase, and was the only site from which the organism could be consistently cultured during a 60-day infection period. The organism could be repeatedly recovered from all levels of the GI tract, and chronic infection was accompanied by sustained low-level fecal shedding. The stomach was identified as the primary site of GI colonization as determined by fluorescent in situ hybridization. Organisms in the stomach were associated with the gastric mucosal surface, and the propensity to colonize the gastric mucosa was observed with 4 different B. pseudomallei isolates. In contrast, B. pseudomallei organisms were present at low numbers within luminal contents in the small and large intestine and cecum relative to the stomach. Notably, inflammatory lesions were not detected in any GI tissue examined in chronically-infected mice. Only low-dose oral or intranasal inoculation led to GI colonization and development of chronic infection of the spleen and liver. Thus, we concluded that in a mouse model of melioidosis B. pseudomallei preferentially colonizes the stomach following oral inoculation, and that the chronically colonized GI tract likely serves as a reservoir for dissemination of infection to extra-intestinal sites

Investigation of osteochondrosis in grazing beef. cattle

Severe lameness attributed to osteochondrosis is described in an extensively managed Brahman herd grazing on improved native pasture. Clinical signs were observed in five animals, three of which were necropsied. The most prominent lesions were in the elbow and stifle joints. There was multiple fissuring and ulceration of thickened articular cartilage with numerous osteochondral bodies present in the joint spaces. All affected animals were entire males sharing a common ancestral sire. Inheritance and gender were suspected to be contributing factors in the development of the disease

Characterisation of Australian isolates of Actinobacillus capsulatus, Actinobacillus equuli, Pasteurella caballi and Bisgaard Taxa 9 and 11

Objective: The objective of this work was to perform a comprehensive phenotypic characterisation of 16 isolates of bacteria previously identified as Actinobacillus equuli. Design: The 16 isolates that had been obtained from Australian animals &endash; 15 from horses and one from a rabbit &endash; were compared with reference strains of A equuli, A capsulatus, Pasteurella caballi and Bisgaard Taxa 9 and 11. Results: The characterisation study demonstrated that only nine of the isolates were A equuli. The other isolates were identified as A capsulatus (the isolate from rabbit), P caballi (one isolate), Bisgaard Taxon 11 (two isolates) and Bisgaard Taxon 9 (one isolate). The final two isolates could not be assigned to any recognised species or taxa. Conclusion: This study has highlighted the importance of a complete characterisation of Actinobacillus-like organisms isolated from horses and rabbits. The study represents the first time that A capsulatus, P caballi and Bisgaard Taxa 9 and 11 have been recognised as being present in Australia

Contagious Caprine Pleuropneumonia

Contagious caprine pleuropneumonia (CCPP), caused by Mycoplasma capricolum subsp. capripneumoniae, is an OIE-listed disease affecting goats and wild ungulate species. CCPP is present in Africa, the Middle East, and Central Asia, but its exact distribution is unknown, particularly in Asia. It is enzootic in the Middle East and East Africa, while it has only been sporadically reported in North and Central Africa and, though suspected, has never been identified in West Africa. In addition, there are very few studies reporting the prevalence and losses induced by CCPP, which are greatly underestimated. This uncertainty over the distribution and impact of CCPP is partly due to the fastidious nature of its etiologic agent, which is difficult to identify, particularly when it circulates in an insidious, mild, or asymptomatic form, favored by the use of antibiotic treatments. However, specific molecular and serological tests are now available for the diagnosis of CCPP, even in the absence of isolation. The main limitation of CCPP surveillance remains the lack of awareness by veterinary services. Vaccines based on inactivated antigens in saponin can induce good protection and their variable quality may now be assessed using a specific ELISA. However, they are very expensive, and there is a paucity of vaccine producers to satisfy their demand. Efforts must urgently be directed to the development of cheaper, quality-controlled vaccines to be extensively used in the field. The global campaign to eradicate “peste des petits ruminants” by 2030 may be a great opportunity to target other goat diseases such as CCPP