Extended-spectrum β-lactamase, shigatoxin and haemolysis capacity of O157 and non-O157 E. coli serotypes from producer-distributor bulk milk

Abstract

We investigated for virulence genes (stx1, stx2 and hlyA), serotypes and extended-spectrum βlactamases (ESBLs) producing capacity in O157 and non-O157 Escherichia coli isolated from producer-distributor bulk milk (PDBM). Fifteen different E. coli O-serogroups were observed from the isolates (n=121). The prevalence of stx1 and stx2 genes among the E. coli isolates was 8.3% and 11.6% (n=121), respectively, while 5.8% harboured both stx1 and stx2. Four E. coli isolates (3.3%) had ESBLs producing capacity, resisted multiple cephalosporins and aztreonam, and carried stx genes. Cluster analysis using GTG 5 finger printing revealed a diversity of E. coli seropathotypes in PDBM which are known to be associated with human diarrhoeal diseases. These results highlight a potential risk posed on human health by the consumption of PDBM contaminated with pathogenic E. coli. A further quantitative risk assessment of the impact of pathogenic E. coli contamination in PDBM on human health is therefore recommended.

Enteroaggregative Escherichia coli is the predominant diarrheagenic E. coli pathotype among irrigation water and food sources in South Africa

“…The first study was initiated by The South African Department of Agriculture and Water Research Commission to help characterize the bacterial quality of South African irrigation water (Aijuka et al, 2015). A high prevalence of faecal indicators within milk sold by unregulated retailers alarmed the South African Dairy Development Agency which subsequently initiated the second study to characterize its microbiological quality (Ntuli et al, 2017(Ntuli et al, , 2016.…”

Quantitative Risk Assessment of Hemolytic Uremic Syndrome Associated with Consumption of Bulk Milk Sold Directly from Producer to Consumer in South Africa

“…and pasteurized PDBM samples, from all the provinces in SA, reported in previous studies by Ntuli et al (44,45) were incorporated in the estimation of STEC concentration. The studies reported STEC prevalence of 11.0 and 7.7% in raw and pasteurized PDBM samples from all the provinces in SA, respectively.…”

“…Shigatoxin producing E. coli O157:H7 is still recognized as epidemiologically significant world-wide, however, in some geographical regions, non-O157 STEC (O26, O103, O111 and O145) are becoming prominent as important E. coli pathotypes (13,28). Recent reports on raw and pasteurized PDBM in South Africa (SA) indicated prevalence of STEC O157 and non-O157 ranging from 10 -54% (5,36,44,45). Ntuli et al (45) documented emerging non-O157 STEC O2, O9, O20, O43, O64, O68, O83, O112, O155 and O157 in PDBM in SA.…”

“…In SA, there are no official data existing on the incidence of HUS linked to STEC contaminated food. Although, several studies have isolated STEC from humans and livestock faeces, water and food (1,26,41,45).…”

“…Studies carried out in SA on producer-distributor bulk milk (PDBM) revealed that the milk can be a potential public health threat as a result of E. coli pathotypes (5,36,44,45).…”