Implications of stx loss for clinical diagnostics of Shiga toxin-producing Escherichia coli

AbstractThe dynamics related to the loss ofstx genes from Shiga toxin-producingEscherichia coli remain unclear. Current diagnostic procedures have shortcomings in the detection and identification of STEC. This is partly owing to the fact thatstx genes may be lost during an infection or in the laboratory. The aim of the present study was to provide new insight into in vivo and in vitrostx loss in order to improve diagnostic procedures. Results from the study support the theory that loss ofstx is a strain-related phenomenon and not induced by patient factors. It was observed that one strain could losestx both in vivo and in vitro. Whole genome comparison ofstx-positive andstx-negative isolates from the same patient revealed that different genomic rearrangements, such as complete or partial loss of the parent prophage, may be factors in the loss ofstx. Of diagnostic interest, it was shown that patients can be co-infected with differentE. coli pathotypes. Therefore, identification ofeae-positive, butstx-negative isolates should not be interpreted as “Shiga toxin-lost”E. coli without further testing. Growth and recovery of STEC were supported by different selective agar media for different strains, arguing for inclusion of several media in STEC diagnostics.
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research