Characterization of bacterial pathogens in rural and urban irrigation water

Abstract

The study aimed to compare the bacteriological quality of an urban and rural irrigation water source. Bacterial counts, characterization, identification and diversity of aerobic bacteria were determined. Escherichia coli isolated from both sites was subjected to antibiotic susceptibility testing, virulence gene (Stx1/Stx2 and eae) determination and (GTG) 5 Rep-PCR fingerprinting. Low mean monthly counts for aerobic spore formers, anaerobic spore formers and Staphylococcus aureus were noted although occasional spikes were observed. The most prevalent bacterial species at both sites were Bacillus spp., E. coli and Enterobacter spp.Additionally, E. coli and Bacillus spp. were most prevalent in winter and summer respectively. Resistance to at least one antibiotic was 84% (rural) and 83% (urban). Highest resistance at both sites was to cephalothin and ampicillin. Prevalence of E. coli possessing at least one virulence gene (Stx1/Stx2 and eae) was 15% (rural) and 42% (urban). All (rural) and 80% (urban) of E. coli possessing virulence genes showed antibiotic resistance. Complete genetic relatedness (100%) was shown by 47% of rural and 67% of urban E. coli isolates. 1Results from this study show that surface irrigation water sources regardless of geographical location and surrounding land-use practices can be reservoirs of similar bacterial pathogens.

Determining the Potential Link between Irrigation Water Quality and the Microbiological Quality of Onions by Phenotypic and Genotypic Characterization of Escherichia coli Isolates

“…The resistance to multiple antimicrobial agents of the E. coli isolates from irrigation water and onions might have been due to the river being downstream of municipal sewage works close to an urban area, as was reported in similar studies in South Africa (1,37). Similar to our study, high resistance to ampicillin was noted in E. coli isolates from the Umgeni and Palmiet rivers (37).…”

“…The findings of this study contribute to the increasing concern about the microbiological quality of surface water sources in South Africa that are used for irrigation and also for drinking water by rural communities (1,9,18,42). However, although the E. coli counts of the primary irrigation source were unacceptably high, a reduction in numbers was observed for the dam water.…”

“…Phenotypic (antimicrobial) and genotypic (virulence gene prevalence, DNA fingerprinting) characterizations of E. coli (including 0157:H7) isolates from different sources, i.e., irrigation water, soil, animal and human feces, meat, and lettuce, have been used to determine whether any of these sources can act as a source of fecal contamination (1,3,22). The resistance to multiple antimicrobial agents of the E. coli isolates from irrigation water and onions might have been due to the river being downstream of municipal sewage works close to an urban area, as was reported in similar studies in South Africa (1,37).…”

“…Phenotypic (antimicrobial) and genotypic (virulence gene prevalence, DNA fingerprinting) characterization of E. coli (including 0157:H7) isolates from different sources, i.e., irrigation water, soil, animal and human feces, meat, and lettuce, have been used to determine whether any of these sources can act as a source of fecal contamination (1,3,4,22). Ateba and Mbewe (5) showed that enterobacterial repetitive intergenic consensus (ERIC) PCR analysis was able to distinguish among E. coli 0157:H7 isolates from a particular sampling site and/or species.…”

Assessment of irrigation water quality and microbiological safety of leafy greens in different production systems

“…Rainfall events increase concentrations of pathogens and indicator organisms in rivers, and reservoirs owing to surface run‐off (Pachepsky et al, ). The use of poor microbiological quality irrigation water further increases the risk of contaminating irrigated produce (Aijuka, Charimba, Hugo, & Buys, ) especially when using overhead irrigation (Castro‐Ibanez et al, ). A previous study indicated the potential effect of contaminated irrigation water on preharvest vegetables (Ijabadeniyi et al, ).…”