Prevalence of Taxa of Pasteurellaceae Among Populations of Healthy Captive Psittacine Birds

Pasteurella sp. associated with fatal septicaemia in six African elephants

The sudden mortality of African elephants (Loxodonta africana) in Botswana and Zimbabwe in 2020 provoked considerable public interest and speculation. Poaching and malicious poisoning were excluded early on in the investigation. Other potential causes included environmental intoxication, infectious diseases, and increased habitat stress due to ongoing drought. Here we show evidence of the mortalities in Zimbabwe as fatal septicaemia associated with Bisgaard taxon 45, an unnamed close relative of Pasteurella multocida. We analyse elephant carcasses and environmental samples, and fail to find evidence of cyanobacterial or other intoxication. Post-mortem and histological findings suggest a bacterial septicaemia similar to haemorrhagic septicaemia caused by P. multocida. Biochemical tests and 16S rDNA analysis of six samples and genomic analysis of one sample confirm the presence of Bisgaard taxon 45. The genome sequence contains many of the canonical P. multocida virulence factors associated with a range of human and animal diseases, including the pmHAS gene for hyaluronidase associated with bovine haemorrhagic septicaemia. Our results demonstrate that Bisgaard taxon 45 is associated with a generalised, lethal infection and that African elephants are susceptible to opportunistically pathogenic Pasteurella species. This represents an important conservation concern for elephants in the largest remaining metapopulation of this endangered species.

Reclassification of Bisgaard taxon 37 and taxon 44 as Psittacicella melopsittaci gen. nov., sp. nov., Psittacicella hinzii sp. nov. and Psittacicella gerlachiana sp. nov. within Psittacicellaceae fam. nov. of the order Pasteurellales

Bacteria isolated from lesions as well as apparently normal tissues of psittacine birds have previously been reported as taxon 37 and taxon 44 of Bisgaard. 16S rRNA gene sequence comparisons revealed a distant relationship to members of Pasteurellaceae at the species, genus and family levels. The polar lipid profile consisted of the major components phosphatidylethanolamine and phosphatidylglycerol. A new family Psittacicellaceae fam. nov. is proposed with the type genus Psittacicella gen. nov. The new genus Psittacicella includes the type species Psittacicella melopsittaci sp. nov. with type strain B96/4^T (=CCUG 70858^T=DSM 105476^T), Psittacicella hinzii sp. nov. with type strain 111^T (=CCUG 52861^T=CCM 8842^T) and Psittacicella gerlachiana sp. nov. with type strain EEAB3T1^T (=CCUG 70857^T=DSM 105477^T). In addition to the major polar lipids, strain 111^T possessed the non-identified aminophospholipids APL1 and APL2 and trace amounts of four lipids (L1-L4) whereas strain B94/4^T showed the minor unidentified aminophospholipids APL3 and APL2 and trace amounts of unidentified lipid L3. These results demonstrate that strain B96/4^T can be distinguished from 111^T based on presence/absence of the unidentified lipids APL1 and APL3. The total polar lipid profile of strain EEAB3T1^T differed from B96/4^Tonly in one minor lipid. Strain B96/4^T can further be distinguished from 111^T by acid formation from trehalose and raffinose and the α-glucosidase test. Strains 111^T and EEAB3T1^T can be separated based on acid formation from trehalose and the α-glucosidase test. Strains B96/4^T and EEAB3T1^T can be separated by acid formation from raffinose and eight signature indels in the RpoB protein.