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Many saprophytic bacteria have LuxR-I-type acyl-homoserine lactone (AHL) quorum-sensing systems that may be important for competing with other bacteria in complex soil communities. LuxR AHL receptors specifically interact with cognate AHLs to cause changes in expression of target genes. Some LuxR-type AHL receptors have relaxed specificity and are responsive to non-cognate AHLs. These promiscuous receptors might be used to sense and respond to AHLs produced by other bacteria by eavesdropping. We are interested in understanding the role of eavesdropping during interspecies competition. The soil saprophyte Chromobacterium subtsugae has a single AHL circuit, CviR-I, which produces and responds to N-hexanoyl-HSL (C6-HSL). The AHL receptor CviR can respond to a variety of AHLs in addition to C6-HSL. In prior studies we have utilized a coculture model with C. subtsugae and another soil saprophyte, Burkholderia thailandensis . Using this model, we previously showed that promiscuous activation of CviR by B. thailandensis AHLs provides a competitive advantage to C. subtsugae . Here, we show that B. thailandensis AHLs activate transcription of dozens of genes in C. subtsugae, including the hcnABC genes coding for production of hydrogen cyanide. We show that hydrogen cyanide production is population density-dependent and demonstrate that the cross-induction of hydrogen cyanide by B. thailandensis AHLs provides a competitive advantage to C. subtsugae . Our results provide new information on C. subtsugae quorum sensing and are the basis for future studies aimed at understanding the role of eavesdropping in interspecies competition.

Many saprophytic bacteria have LuxR-I-type acyl-homoserine lactone (AHL) quorum-sensing systems that may be important for competing with other bacteria in complex soil communities. LuxR AHL receptors specifically interact with cognate AHLs to cause changes in expression of target genes. Some LuxR-type AHL receptors have relaxed specificity and are responsive to non-cognate AHLs. These promiscuous receptors might be used to sense and respond to AHLs produced by other bacteria by eavesdropping. We are interested in understanding the role of eavesdropping during interspecies competition. The soil saprophyteChromobacterium subtsugaehas a single AHL circuit, CviR-I, which produces and responds toN-hexanoyl-HSL (C6-HSL). The AHL receptor CviR can respond to a variety of AHLs in addition to C6-HSL. In prior studies we have utilized a coculture model withC. subtsugaeand another soil saprophyteBurkholderia thailandensis. Using this model, we previously showed that promiscuous activation of CviR byB. thailandensisAHLs provides a competitive advantage toC. subtsugae. Here, we show thatB. thailandensisAHLs activate transcription of dozens of genes inC. subtsugae, including thehcnABCgenes coding for production of hydrogen cyanide. We show that hydrogen cyanide production is population density-dependent and demonstrate that the cross-induction of hydrogen cyanide byB. thailandensisAHLs provides a competitive advantage toC. subtsugae. Our results provide new information onC. subtsugaequorum sensing and are the basis for future studies aimed at understanding the role of eavesdropping in interspecies competition.IMPACT STATEMENTIn quorum sensing, population density-dependent changes in gene regulation are the result of a cytoplasmic transcription regulator binding to a quorum sensing signal. The signal-receptor interaction is considered to be specific to ensure fidelity of the system. However, some quorum-sensing receptor proteins have relaxed specificity and can recognize and respond to a range of signals. These promiscuous receptors might provide some benefit by enabling interspecies activation of quorum sensing by “eavesdropping,” although the potential benefits of eavesdropping are not well studied. The current study utilizes a dual-species laboratory competition model, where one species has a promiscuous signal receptor and can respond to signals produced by the other species. In our study, we identify the signals that enable quorum sensing cross talk and show that cross talk promotes competition by inducing hydrogen cyanide production. Our results highlight how quorum sensing-enabled interspecies cross talk might provide an advantage during competition and provide a new basis for understanding how receptor-signal pairs might evolve in natural environments.DATA SUMMARYThe authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.

Surgical patient safety is a priority in the national and international quality healthcare improvement strategies. The objective of the study was to implement a collaborative intervention with multiple components and to evaluate the impact of the patient surgical safety checklist (SSC) application. This is a prospective, longitudinal multicenter study with a 7-month follow-up period in 2009 based on a collaborative intervention for the implementation of a 24 item-SSC distributed in 3 different stages (sign in, time out, sign out) for its application to the surgical patient. A total number of 27 hospitals participated in the strategy. The global implementation rate was 48% (95%CI, 47.6%-48.4%) during the evaluation period. The overall compliance with all the items of the SSC included in each stage (sign in, time out, sign out) was 75,1% (95%CI, 73.5%-76.7%) for the sign in, 77.1% (95%CI, 75.5%-78.6%) for the time out and 88.3% (95%CI, 87.2%-89.5%) for the sign out respectively. The individual compliance with each item of the SSC has remained above 85%, except for the surgical site marking with an adherence of 67.4% (95%CI, 65.7%-69.1%)] and 71.2% (95%CI, 69.6%-72.9%)] in the sign in and time out respectively. The SSC was successfully implemented to 48% of the surgeries performed to the participating hospitals. The global compliance with the SSC was elevated and the intervention trend was stable during the evaluation period. Strategies were identified to allow of a higher number of surgeries with application of the SSC and more professional involvement in measures compliance such as surgical site marking.

Surgical patient safety is a priority in the national and international quality healthcare improvement strategies. The objective of the study was to implement a collaborative intervention with multiple components and to evaluate the impact of the patient surgical safety checklist (SSC) application. This is a prospective, longitudinal multicenter study with a 7-month follow-up period in 2009 based on a collaborative intervention for the implementation of a 24 item-SSC distributed in 3 different stages (sign in, time out, sign out) for its application to the surgical patient. A total number of 27 hospitals participated in the strategy. The global implementation rate was 48% (95%CI, 47.6%-48.4%) during the evaluation period. The overall compliance with all the items of the SSC included in each stage (sign in, time out, sign out) was 75,1% (95%CI, 73.5%-76.7%) for the sign in, 77.1% (95%CI, 75.5%-78.6%) for the time out and 88.3% (95%CI, 87.2%-89.5%) for the sign out respectively. The individual compliance with each item of the SSC has remained above 85%, except for the surgical site marking with an adherence of 67.4% (95%CI, 65.7%-69.1%)] and 71.2% (95%CI, 69.6%-72.9%)] in the sign in and time out respectively. The SSC was successfully implemented to 48% of the surgeries performed to the participating hospitals. The global compliance with the SSC was elevated and the intervention trend was stable during the evaluation period. Strategies were identified to allow of a higher number of surgeries with application of the SSC and more professional involvement in measures compliance such as surgical site marking.