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The human enteric bacterial pathogen Salmonella enterica causes approximately 1.35 million cases of food borne illnesses annually in the United States. Of these salmonellosis cases, almost half are derived from the consumption of fresh, raw produce. Although epiphytic S . enterica populations naturally decline in the phyllosphere, a subset of phytophagous insects have recently been identified as biological multipliers, consequently facilitating the growth of bacterial populations. We investigated whether tomato leaves with macroscopic feeding damage, caused by infestation of adult Western flower thrips ( Frankliniella occidentalis ), support higher S . enterica populations. To explore this hypothesis, we assessed S . enterica populations in response to thrips feeding by varying insect density, plant age, and the gender of the insect. As a reference control, direct leaf damage analogous to thrips feeding was also evaluated using directed, hydraulic pressure. In a supplementary set series of experiments, groups of F . occidentalis infested tomato plants were later inoculated with S . enterica to determine how prior insect infestation might influence bacterial survival and persistence. Following an infestation period, leaves visibly damaged by adult F . occidentalis supported significantly higher S . enterica populations and resulted in greater amounts of electrolyte leakage (measured as electrical conductivity) than leaves lacking visible feeding damage. Plant age did not significantly influence S . enterica populations or estimates of electrolyte leakage, independent of initial infestation. Additionally, the gender of the insect did not uniquely influence S . enterica population dynamics. Finally, applications of aggressive water bombardment resulted in more electrolyte leakage than leaves damaged by F . occidentalis , yet supported comparable S . enterica populations. Together, this study indicates that F . occidentalis feeding is one of the many potential biological mechanisms creating a more habitable environment for S . enterica .

Hemipteran insects are ubiquitous inhabitants of the phyllosphere. Changes in microbial phyllosphere communities have recently been demonstrated following infestation by Macrosteles quadrilineatus (Aster Leafhopper). Although epiphytic Salmonella enterica populations naturally decline in the phyllosphere of plants, M. quadrilineatus infestation facilitated the growth of the bacterial pathogen populations. Here, we demonstrate that cellular damage by insect stylet penetration results in a localized beneficial niche on the leaf surface, leading to enhanced S. enterica populations. We measured S. enterica populations and colonization patterns on plants infested with Hemipterans with distinct feeding behaviors. M. quadrilineatus infestation resulted in higher solute leakage and significantly greater bacterial populations than plants absent of insects. Following immigration via contaminated irrigation water, the highest populations of S. enterica are naturally found on the tips of tomato leaflets. We discovered M. quadrilineatus feeding preference altered the natural distribution of S. enterica populations, and that the presence of S. enterica altered the distribution of probing attempts. These findings elucidate how cellular damage resulting from insect feeding drives changes in bacterial colonization of the phyllosphere.

Background To determine the prevalence of RET rearrangement genes, RET copy number gains and expression in tumor samples from four Phase III non-small-cell lung cancer (NSCLC) trials of vandetanib, a selective inhibitor of VEGFR, RET and EGFR signaling, and to determine any association with outcome to vandetanib treatment. Methods Archival tumor samples from the ZODIAC ( NCT00312377 , vandetanib ± docetaxel), ZEAL ( NCT00418886 , vandetanib ± pemetrexed), ZEPHYR ( NCT00404924 , vandetanib vs placebo) and ZEST ( NCT00364351 , vandetanib vs erlotinib) studies were evaluated by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in 944 and 1102 patients. Results The prevalence of RET rearrangements by FISH was 0.7% (95% CI 0.3–1.5%) among patients with a known result. Seven tumor samples were positive for RET rearrangements (vandetanib, n  = 3; comparator, n  = 4). 2.8% ( n  = 26) of samples had RET amplification (innumerable RET clusters, or ≥7 copies in > 10% of tumor cells), 8.1% ( n  = 76) had low RET gene copy number gain (4–6 copies in ≥40% of tumor cells) and 8.3% ( n  = 92) were RET expression positive (signal intensity ++ or +++ in >10% of tumor cells). Of RET -rearrangement-positive patients, none had an objective response in the vandetanib arm and one patient responded in the comparator arm. Radiologic evidence of tumor shrinkage was observed in two patients treated with vandetanib and one treated with comparator drug. The objective response rate was similar in the vandetanib and comparator arms for patients positive for RET copy number gains or RET protein expression. Conclusions We have identified prevalence for three RET biomarkers in a population predominated by non-Asians and smokers. RET rearrangement prevalence was lower than previously reported. We found no evidence of a differential benefit for efficacy by IHC and RET gene copy number gains. The low prevalence of RET rearrangements (0.7%) prevents firm conclusions regarding association of vandetanib treatment with efficacy in the RET rearrangement NSCLC subpopulation. Trial registration Randomized Phase III clinical trials ( NCT00312377 , ZODIAC; NCT00418886 , ZEAL; NCT00364351 , ZEST; NCT00404924 , ZEPHYR).