Unveiling a Listeria monocytogenes Outbreak in a Rabbit Farm: Clinical Manifestation, Antimicrobial Resistance, Genomic Insights and Environmental Investigation

• Published in: Microorganisms (Basel) 2024-04, Vol.12 (4), p.785
• Main Authors: Rodrigues, Inês C, Ribeiro-Almeida, Marisa, Silveira, Leonor, Prata, Joana C, de Carvalho, André Pinto, Roque, Carla, Gomes, João Paulo, Borges, Vítor, Pista, Ângela, Martins da Costa, Paulo
• Format: Article
• Language: English
• Subjects: Abortion; Animal health; Animal welfare; Animals; Antibiotic resistance; Antibiotics; Antimicrobial agents; Antimicrobial resistance; Artificial insemination; clinical manifestation; Clustering; Drinking water; Epidemics; Exudates; Exudation; Farms; Flooring; Food safety; genomic profiling; Genomics; Infections; Ionophores; Lethargy; Lincosamides; Listeria; Listeria monocytogenes; Listeriosis; Necropsy; NorB protein; Nucleotide sequence; Outbreaks; rabbit farm; Rabbits; Sheep; Splenomegaly; Sulfamethoxazole; Trimethoprim; Uterus
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms12040785

poses a threat to both human and animal health. This work describes an outbreak in a Portuguese rabbit farm, detailing the isolates' clinical manifestations, necropsy findings, and phenotypic and genomic profiles. Clinical signs, exclusively observed in does, included lethargy and reproductive signs. examination of does revealed splenomegaly, hepatomegaly with a reticular pattern, pulmonary congestion, and haemorrhagic lesions in the uterus, with thickening of the uterine wall and purulent greyish exudates. Positive samples were identified in fattening and maternity units across different samples, encompassing does and environmental samples. Core-genome Multi Locus Sequence Typing (cgMLST) analysis confirmed the outbreak, with the 16 sequenced isolates (lineage II, CC31, and ST325) clustering within a ≤2 allelic difference (AD) threshold. Antimicrobial susceptibility testing for five antibiotics revealed that 15 out of 19 outbreak isolates were resistant to sulfamethoxazole-trimethoprim (SXT). Concordantly, all SXT-resistant sequenced isolates were found to exclusively harbour a plasmid containing a trimethoprim-resistance gene ( ), along with loci linked to resistance to lincosamides (lnuG), macrolides (mphB), and polyether ionophores (NarAB operon). All sequenced outbreak isolates carried the antibiotic resistance-related genes , , , , , , and . The outbreak cluster comprises isolates from does and the environment, which underscores the ubiquitous presence of and emphasizes the importance of biosecurity measures. Despite limited data on listeriosis in rabbit farming, this outbreak reveals its significant impact on animal welfare and production.