Restaurant inspection frequency: The RestoFreq Study.

OBJECTIVES: Foodborne illness is an important contributor to morbidity and health system costs in Canada. Using number of critical hazards as a proxy for food safety, we sought to better understand how to improve food safety in restaurants. We compared the current standard of annual inspections to twice-yearly inspections among restaurants "at risk" for food safety infractions. These were restaurants that had three or more elevated-risk inspection ratings in the preceding 36 months. METHODS: We conducted a two-arm randomized controlled trial between November 2012 and October 2014. The intervention was twice-yearly routine restaurant inspection compared to standard once-yearly routine inspection. Included were all restaurants within Saskatoon Health Region that were assessed as "at risk", with 73 restaurants in the intervention arm and 78 in the control arm. Independent sample t-tests were conducted between groups to compare: i) average number of critical hazards per inspection; and ii) proportion of inspections resulting in a rating indicating an elevated hazard. RESULTS: Over time we noted statistically significant improvements across both study arms, in number of both critical food safety hazards (decreased by 61%) and elevated-risk inspection ratings (decreased by 45%) (p < 0.0001). We observed no significant differences between the two groups pre- or post-intervention. CONCLUSION: Results suggest increasing the number of annual routine inspections in high-risk restaurants was not associated with a significant difference in measures of compliance with food safety regulations. Findings of this study do not provide evidence supporting increased frequency of restaurant inspection from annually to twice annually.

Location of dual sites in E. coli FtsZ important for degradation by ClpXP; one at the C-terminus and one in the disordered linker.

ClpXP is a two-component ATP-dependent protease that unfolds and degrades proteins bearing specific recognition signals. One substrate degraded by Escherichia coli ClpXP is FtsZ, an essential cell division protein. FtsZ forms polymers that assemble into a large ring-like structure, termed the Z-ring, during cell division at the site of constriction. The FtsZ monomer is composed of an N-terminal polymerization domain, an unstructured linker region and a C-terminal conserved region. To better understand substrate selection by ClpXP, we engineered FtsZ mutant proteins containing amino acid substitutions or deletions near the FtsZ C-terminus. We identified two discrete regions of FtsZ important for degradation of both FtsZ monomers and polymers by ClpXP in vitro. One region is located 30 residues away from the C-terminus in the unstructured linker region that connects the polymerization domain to the C-terminal region. The other region is near the FtsZ C-terminus and partially overlaps the recognition sites for several other FtsZ-interacting proteins, including MinC, ZipA and FtsA. Mutation of either region caused the protein to be more stable and mutation of both caused an additive effect, suggesting that both regions are important. We also observed that in vitro MinC inhibits degradation of FtsZ by ClpXP, suggesting that some of the same residues in the C-terminal site that are important for degradation by ClpXP are important for binding MinC.