Anti-STX2 monoclonal antibody, clone 6C7.2

PCR-based testing for Shiga toxin producing Escherichiacoli (STEC) directly from fecal samples is increasingly being implemented in routine diagnostic laboratories. These methods aim to detect clinically relevant amounts of microbes and not stx-carrying phages or low backgrounds of STEC. We present a diagnostic procedure and results from 1 year of stx-targeted real-time PCR of fecal samples from patients with gastrointestinal symptoms in Norway. A rapid stx2 subtyping strategy is described, which aims to quickly reveal the virulence potential of the microbe. stx was detected in 22 of 3320 samples, corresponding to a PCR positive rate of 0.66%. STEC were cultured from 72% of the PCR positive samples. Four stx1 isolates, eight stx2 isolates, and four isolates with both stx1 and stx2 were identified. With the method presented, stx-carrying phages are not commonly detected. Our results support the use of molecular testing combined with classical culture techniques for routine diagnostic purposes.

This study was carried out to determine the prevalence of E. coli O157: H7 in mastitic bovine milk, to investigate the major virulence genes [shiga toxins (stx1 and stx2), intimin (eae), enterohaemolysin (ehlyA), and traslocated intimin receptor (tir)], antibiotic resistance profiles and clonality of the isolates. A total of 484 bovine mastitic milk samples collected from dairy farms in Aydin is a county situated by Aegean Sea at the west part of Turkey. The serotype of the isolates was confirmed by the presence of specific genes using polymerase chain reaction (PCR). Presence of virulence genes was also tested by PCR. Resistance to 13 antimicrobial agents was investigated by the disk diffusion method. The clonality was determined by enterobacterial repetitive intergenic consensus (ERIC) PCR. From 484 bovine milk with mastitis a total of 8 (1.65%) E. coli O157: H7 was isolated from 5 farms. Among virulence genes tested, ehlyA was positive for all 8 (100.0%) isolates, 7 isolates carried (87.5%) eae, tir and stx2 genes. Isolates were all susceptible to the antimicrobials tested except to tetracycline for two (25.0%) and to streptomycin for one (12.5%). The clonal spread was detected among the animals with mastitis by ERIC PCR. Among 8 strains tested, a total of 6 profiles were detected. There were two couples of "identical" isolates. The four isolates from the same farm appeared to be closely related, and distantly related to the isolates from other farms. Presence of E. coli O157: H7 strains in mastitic bovine milks may cause public health problems. We suggest that there is a need for improving the hygienic conditions of the farms which may help reduce transmission of E. coli O157: H7 to humans.