The incidence of diarrhoeagenic Escherichia coli in minced beef and boerewors

Abstract

A survey of diarrhoeagenic Escherichia coli (DEC) was carried out on 21 minced beef and 21 boerewor (a traditional South African fresh sausage) samples purchased from 30% of butcheries in the Bloemfontein District of South Africa. The samples were cultivated on standard plate count agar for aerobic plate counts and chromocult coliform agar for coliform and E. coli counts without enrichment. Diarrhoeagenic E. coli were isolated after enrichment in MacConkey broth followed by cultivation on chromocult coliform agar. The resultant E. coli colonies were selected and serotyped using the slide agglutination test for DEC. Eight (38.10%) minced beef samples were positive for DEC. The 8 positive samples consisted of 5 (23.81%) EPEC and 1 each (4.76%) of EIEC, EAggEC, and VTEC. A total of 100 isolates were serotyped (5 from each sample) and these comprised 6 (6%) EPEC serotypes (3×O18; 1×O125; and 1×O142), and 1 (1%) each of EIEC (1×O128ac), EAggEC (1×O44) and VTEC (1×O26). Boerewors had 6 (28.57%) samples that were positive for DEC. EPEC and VTEC were the virotypes that were isolated at 23.81% (5/21) and 4.76% (1/21) respectively. A total of 105 isolates were serotyped (5 from each sample) and these comprised 7 (6.66%) EPEC (3×O18, 2×O125, 1×O55 and 1×O142); and 1 (0.95%) VTEC (1×O26). EPEC were the most frequent virotype while VTEC were the most virulent virotype recovered from both products. No E. coli O157:H7 were recovered.