Occurrence and Distribution of Enterobacteriaceae and Molecularly Characterised Yersinia Species Isolated from Pig Faeces and Cow Intestines
Janet Omolola Alimi *
Perishable Crops Research Department, Nigerian Stored Products Research Institute, Ilorin, Kwara State, Nigeria.
Samuel Temitope Ogunbanwo
Department of Microbiology, University of Ibadan, Ibadan, Oyo State, Nigeria.
John Praise Alimi
Durable Crops Research Department, Nigerian Stored Products Research Institute, Ilorin, Kwara State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aim: To determine the occurrence and distribution of Enterobacteriaceae and Yersiniaceae in pig faeces and cow intestines and molecularly characterise selected Yersinia isolates using 16S rRNA gene sequencing.
Study Design: Cross-sectional laboratory study of bacterial isolation, phenotypic identification, and molecular characterisation from livestock.
Methodology: A total of 157 samples comprising faeces from adult pigs, growers and finishers, weaners and piglets, and cow intestines were collected and processed using standard microbiological procedures. Bacterial isolates were identified by conventional cultural and biochemical methods. Eleven representative Yersinia isolates were selected for molecular characterisation using 16S rRNA gene amplification and sequencing, followed by sequence comparison for species identification and genetic relatedness.
Results: A total of 213 bacterial isolates belonging to the families Enterobacteriaceae and Yersiniaceae were recovered. Yersinia species constituted the largest proportion of isolates (40.38%), followed by Klebsiella aerogenes (12.68%), Proteus mirabilis (7.51%), Enterobacter cloacae (6.10%), and Citrobacter freundii (5.16%). Other organisms identified included Escherichia coli, Klebsiella pneumoniae, Alcaligenes faecalis, Shigella spp., Salmonella Typhi, Providencia alcalifaciens, Aeromonas jandaei, and Pseudomonas species. Molecular analysis identified four Yersinia species, namely Yersinia enterocolitica, Yersinia pseudotuberculosis, Yersinia intermedia, and Yersinia kristensenii. Grower and finisher pigs accounted for the highest proportion of Yersinia isolates (54.5%), whereas adult pigs and weaners/piglets each contributed 18.2%, and cow intestines accounted for 9.1%. Sequence analysis revealed high genetic relatedness among the characterised isolates, with nucleotide sequence similarities ranging from 99.59% to 100%.
Conclusion: The predominance of Yersinia species, particularly Y. enterocolitica, among pig samples confirms the important role of swine as reservoirs of potentially pathogenic Yersinia. The occurrence of Y. pseudotuberculosis further highlights the zoonotic significance of these animals. The findings emphasise the need for continuous surveillance, improved farm hygiene, and molecular monitoring of livestock-associated bacterial pathogens to reduce the risk of foodborne transmission and safeguard public health.
Keywords: Yersinia enterocolitica, Yersinia pseudotuberculosis, Enterobacteriacea, Yersiniaceae, livestock, molecular characterisation, zoonosis