Aerobic bacterial flora of the nasal cavity in Gulf of California sea lion (Zalophus californianus) pups

Neisseria montereyensis sp. nov., Isolated from Oropharynx of California Sea Lion (Zalophus californianus): Genomic, Phylogenetic, and Phenotypic Study

A novel Neisseria strain, designated CSL10203-ORH2^T, was isolated from the oropharynx of a wild California sea lion (Zalophus californianus) that was admitted to The Marine Mammal Center in California, USA. The strain was originally cultured from an oropharyngeal swab on BD Phenylethyl Alcohol (PEA) agar with 5% sheep blood under aerobic conditions. Phylogenetic analyses based on 16S rRNA, rplF, and rpoB gene sequences and the core genome sequences indicated that the strain was most closely related to only N. zalophi CSL 7565^T. The average nucleotide identity and digital DNA-DNA hybridization values between strain CSL10203-ORH2^T and the closely related species N. zalophi CSL 7565^T were 89.84 and 39.70%, respectively, which were significantly lower than the accepted species-defined thresholds for describing novel prokaryotic species at the genomic level. Both type strains were phenotypically similar but can be easily and unambiguously distinguished between each other by the analysis of their housekeeping genes, e.g., rpoB, gyrB, or argF. The major fatty acids in both type strains were C_12:0, C_16:0, C_16:1-c9, and C_18:1-c11. Based on the genomic, phenotypic, and phylogenetic properties, the novel strain represents a novel species of the genus Neisseria, for which the name Neisseria montereyensis sp. nov. with the type strain CSL10203-ORH2^T (= DSM 114706^T = CCUG 76428^T = NCTC 14721^T) is proposed. The genome G + C content is 45.84% and the complete draft genome size is 2,310,535 bp.

Isolation, identification and virulence gene characterization of Aeromona dhakensis isolated from sea lion (Zalophus californianus)

Species of Aeromonas are ubiquitous pathogens of fish and aquatic animals and can infect humans and other animals through the food chain. However, there are few reports of marine mammalian infections. In 2020, a sea lion (Zalophus californianus) died acutely at an aquarium in Harbin, Heilongjiang Province, China. In order to explore the cause of death, we dissected the animal and observed pathological changes. Ogans were aseptically collected and used for bacterial isolation and culture. This revealed that the sea lion had died of sepsis caused by a bacterial infection. Isolated bacteria were investigated by morphology, biochemical phenotype and molecular identification, and this determined the pathogen as A. dhakensis. The isolate contained six virulence genes, hlyA, aerA, act, lafA, ela, fla, and was susceptible to most antibiotics. This is the first report of A. dhakensis associated with septicemia in pinnipeds and a description of its virulence and resistance profiles. Its presence in aquatic environments poses a potential threat to marine mammals.

Non-pathogenic Neisseria: members of an abundant, multi-habitat, diverse genus

The genus Neisseria contains the important pathogens Neisseria meningitidis and Neisseria gonorrhoeae. These Gram-negative coccoid bacteria are generally thought to be restricted to humans and inhabit mucosal surfaces in the upper respiratory and genito-urinary tracts. While the meningococcus and gonococcus have been widely studied, far less attention has been paid to other Neisseria species. Here we review current knowledge of the distribution of commensal Neisseria in humans and other hosts. Analysis of the microbiome has revealed that Neisseria is an abundant member of the oropharyngeal flora, and we review its potential impact on health and disease. Neisseria also exhibit remarkable diversity, exhibiting both coccoid and rod-shaped morphologies, as well as environmental strains which are capable of degrading complex organic molecules.

Characterization of a Moraxella species that causes epistaxis in macaques

Bacteria of the genus Moraxella have been isolated from a variety of mammalian hosts. In a prior survey of bacteria that colonize the rhesus macaque nasopharynx, performed at the Tulane National Primate Research Center, organisms of the Moraxella genus were isolated from animals with epistaxis, or "bloody nose syndrome." They were biochemically identified as Moraxella catarrhalis, and cryopreserved. Another isolate was obtained from an epistatic cynomolgus macaque at the U.S. Army Medical Research Institute of Infectious Diseases. Based on differences in colony and cell morphologies between rhesus and human M. catarrhalis isolates, we hypothesized that the nonhuman primate Moraxella might instead be a different species. Despite morphological differences, the rhesus isolates, by several biochemical tests, were indistinguishable from M. catarrhalis. Analysis of the cynomolgus isolate by Vitek 2 Compact indicated that it belonged to a Moraxella group, but could not differentiate among species. However, sequencing of the 16S ribosomal RNA gene from four representative rhesus isolates and the cynomolgus isolate showed closest homology to Moraxella lincolnii, a human respiratory tract inhabitant, with 90.16% identity. To examine rhesus macaques as potential hosts for M. catarrhalis, eight animals were inoculated with human M. catarrhalis isolates. Only one of the animals was colonized and showed disease, whereas four of four macaques became epistatic after inoculation with the rhesus Moraxella isolate. The nasopharyngeal isolates in this study appear uniquely adapted to a macaque host and, though they share many of the phenotypic characteristics of M. catarrhalis, appear to form a genotypically distinct species.