ISOLATION AND MOLECULAR IDENTIFICATION OF PAENIBACILLUS SPECIES FROM PIG FARMS IN OGUN STATE, NIGERIA

ABSTRACT

Paenibacillus species are opportunistic pathogens that tend to cause infections in immunocompromised individuals, it is increasingly becoming implicated in human infections but its role in animal farms is not well elucidated, this study is therefore aimed at determining the prevalence of this organism in farm animals, its molecular characterization as well as its antibiotic sensitivity profile. A total of 138 fecal samples were analyzed using standard aerobic and anaerobic culture methods in two farms in Ogun state Nigeria. Out of 138 samples collected, 35(25.4%) were positive for Paenibacillus species. The distribution rates among different categories in each farm included; Boars 1(9.1%), Sows 2(13.3%), Growers/Guilts 4(22.3%) and Weaners/suckers 5(17.9%) for Otta farms and Boars 3(37.5%), Sows 5(33.3%), Growers/Guilts 6(22.2%) and Weaners/Suckers 9(39.1%) for Oke-Aro farm. Oke Aro farm recorded a prevalence of 34.8% while Otta farm had a prevalence rate of 16.7%. Isolates were identified using a polyphasic taxonomic approach known as 16S rRNA plus phenotypic traits. Six Paenibacillus species were identified these included: Paenibacillus konsidensis, Paenibacillus massiliensis, Paenibacillus polymyxa, Paenibacillus timonensis, Paenibacillus amyloticus, Paenibacilus terrae with a range of 95-99% identity. The evolutionary history (phylogenic tree) was inferred using the Neighbor-Joining method based on 16S rRNA sequences, and optimal tree with the sum of branch length = 0.27833917. The antibiotic drug testing demonstrated an encouraging susceptibility pattern for ciprofloxacin (3.91- 62.5mg/ml), tetracycline and clindamycin (31.25-125 mg/ml) while there was multiple drug resistance for metronidazole, chloramphenicol and erythromycin with similar MICs of >125 mg/ml. Plasmid analysis showed that the multiple resistance portrayed by some of the Paenibacillus species in this study were plasmid mediated with plasmid molecular weight of 23130kbp. This study confirms the presence of Paenibacillus species in food animals as a food-borne pathogen as a result pig meat may be vehicles for transmitting this organism to humans, this is worrisome because this study showed this organism has developed multiple drug resistance and with the high consumption of pork meat in Nigeria makes it a threat to public health. Hence it is critical that risk reduction strategies are used throughout the food chain, these strategies includes increased hygiene at both slaughter and meat processing and continued implementation of HACCP systems.