Farm level survey of environmental contamination by pathogenic bacteria : case study of University of Limpopo Experiential Farm

Abstract

Identification of pathogens is a crucial step in the diagnosis of livestock diseases. An insight of bacterial diversity may enable decisions on appropriate treatment and shield farmers from tremendous losses due to disease outbreaks. The aim of this study was to investigate the occurence and diversity of pathogenic bacteria in the environment at University of Limpopo experiential farm using Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spctrometry (MALDI-TOF MS). The diversity of pathogenic bacteria were investigated in environmental samples collected from three different sampling locations within the farm (labelled according to the site of collections as cattle camp (CC), sheep camp (SHC), and goat camp (GC)). Total bacterial counts were calculated using the colony forming unit formula per gram of environmental sample (CFU/g) with the standard spread plate method. High bacterial counts were observed in CC: 7.25x107 cfu/g and 4.5x106 cfu/g for soil and faecal samples respectively while low counts were observed in SHC: 4.8x107cfu/g for soil samples and 3.7x106 cfu/g for faecal samples) for both soil and faecal samples. In soil samples, similar bacterial species were encountered at the different sampling locations. Bacillus species (B. cereus, B. megaterium, B. simplex, B. mycoids, B. weihenstephansis, B. licheniformis and B. endophyticus) were the most dominant across the different sampling locations in the soil samples. Bacillus cereus tested positive in 36 samples (33 %), however, the frequency of isolation dominated in the GC (50 %), SHC (41.6 %) CC with (28 %), and Staphylococcus aureus were the least isolated with a frequency of 1.4 % followed by Listeria monocytogens with 2.8 % frequency in CC. In faecal samples, the occurrence and level of contamination with bacterial species varied across sampling locations with minor similarities observed in SHC and GC. Escherichia coli dominanted CC with 64.2 % frequency, and absent from SHC and GC. This study demonstrated the contamination of opportunistic, food borne bacteria like B.cereus and L. monocytogenes in the experiential farm environment and the need for good hygiene practices to prevent its entry into the food chain