Adaptive Laboratory Evolution of Probiotics toward Oxidative Stress Using a Microfluidic-Based Platform.

Adaptive laboratory evolution (ALE) can be used to make bacteria less susceptible to oxidative stress. An alternative to large batch scale ALE cultures is to use microfluidic platforms, which are often more economical and more efficient. Microfluidic ALE platforms have shown promise, but many have suffered from subpar cell passaging mechanisms and poor spatial definition. A new approach is presented using a microfluidic Evolution on a Chip (EVoc) design which progressively drives microbial cells from areas of lower H2O2 concentration to areas of higher concentration. Prolonged exposure, up to 72 h, revealed the survival of adaptive strains of Lacticaseibacillus rhamnosus GG, a beneficial probiotic often included in food products. After performing ALE on this microfluidic platform, the bacteria persisted under high H2O2 concentrations in repeated trials. After two progressive exposures, the ability of L. rhamnosus to grow in the presence of H2O2 increased from 1 mm H2O2 after a lag time of 31 h to 1 mm after 21 h, 2 mm after 28 h, and 3 mm after 42 h. The adaptive strains have different morphology, and gene expression compared to wild type, and genome sequencing revealed a potentially meaningful single nucleotide mutation in the protein omega-amidase.

Efficacy of a Sonicating Swab for Removal and Capture of Microorganisms from Experimental and Natural Contaminated Surfaces.

Enhancements in swabbing technology to increase sample collection efficacy would benefit the food industry. Specifically, these enhancements would assist the food industry in implementing the FDA Food Safety Modernization Act (FSMA) requirements by improving environmental monitoring effectiveness. A sonicating swab device, an example of an enhanced swabbing technology, was demonstrated previously to remove biofilm from stainless steel more efficiently than a standard cotton swab. Within this study, the performance of the sonicating swab was compared to that of the standard cotton swab for the recovery of Listeria monocytogenes from inoculated surfaces (plastic cutting board, wood cutting board, vinyl floor tile, and quarry clay floor tile). Additionally, we demonstrate the sonicating swab performance for collection of a microbiological sample from used commercial plastic cutting boards (noninoculated) in comparison to cotton swabs, foam swabs, and sponges. The sonicating swab captured significantly (P ≤ 0.05) more L. monocytogenes than the cotton swab for both the quarry tile and wood cutting board, while no significant differences were observed for the plastic cutting board or the vinyl floor tile. The sonicating swab consistently recovered significantly (P ≤ 0.05) more bacteria from the used cutting boards than did the standard cotton swab or the 3M Enviro swab, and it recovered significantly (P ≤ 0.05) more bacteria than the sponge swab for a majority of the time (4 of 6 trials). The results of this study indicate that swab technology can still be improved and that the sonicating swab is a viable technological enhancement which aids microbiological sample collection.IMPORTANCE Swabbing of surface areas for microbial contamination has been the standard for the detection and enumeration of microorganisms for many years. Inadequate surface sampling can result in foodborne illness outbreaks due to biotransfer of harmful microorganisms from food contact surfaces to foods. Swab material type, surface characteristics, and swabbing method used are a few of the factors associated with swabbing that can result in the variability of bacterial cell recovery for detection and enumeration. A previous study highlighted a sonicating swab prototype and its ability to recover cells from a stainless steel surface more efficiently and reliably than a standard swab method (T. A. Branck, M. J. Hurley, G. N. Prata, C. A. Crivello, and P. J. Marek, Appl Environ Microbiol 83:e00109-17, 2017, https://doi.org/10.1128/AEM.00109-17). This study expands upon the capabilities of the sonicating swab technology to recover cells from multiple surface types with increased performance over traditional swabbing methods as a tool to further assist in the prevention of foodborne illness outbreaks.

Efficacy of a Sonicating Swab for Removal and Capture of Listeria monocytogenes in Biofilms on Stainless Steel.

Listeria monocytogenes is of great concern in food processing facilities because it persists in biofilms, facilitating biotransfer. Stainless steel is commonly used for food contact surfaces and transport containers. L. monocytogenes biofilms on stainless steel served as a model system for surface sampling, to test the performance of a sonicating swab in comparison with a standard cotton swab. Swab performance and consistency were determined using total viable counts. Stainless steel coupons sampled with both types of swabs were examined using scanning electron microscopy, to visualize biofilms and surface structures (i.e., polishing grooves and scratches). Laser scanning confocal microscopy was used to image and to quantitate the biofilms remaining after sampling with each swab type. The total viable counts were significantly higher (P ≤ 0.05) with the sonicating swab than with the standard swab in each trial. The sonicating swab was more consistent in cell recovery than was the standard swab, with coefficients of variation ranging from 8.9% to 12.3% and from 7.1% to 37.6%, respectively. Scanning electron microscopic imaging showed that biofilms remained in the polished grooves of the coupons sampled with the standard swab but were noticeably absent with the sonicating swab. Percent area measurements of biofilms remaining on the stainless steel coupons showed significantly (P ≤ 0.05) less biofilm remaining when the sonicating swab was used (median, 1.1%), compared with the standard swab (median, 70.4%). The sonicating swab provided greater recovery of cells, with more consistency, than did the standard swab, and it is employs sonication, suction, and scrubbing.IMPORTANCE Inadequate surface sampling can result in foodborne illness outbreaks from biotransfer, since verification of sanitization protocols relies on surface sampling and recovery of microorganisms for detection and enumeration. Swabbing is a standard method for microbiological sampling of surfaces. Although swabbing offers portability and ease of use, there are limitations, such as high user variability and low recovery rates, which can be attributed to many different causes. This study demonstrates some benefits that a sonicating swab has over a standard swab for removal and collection of microbiological samples from a surface, to provide better verification of surface cleanliness and to help decrease the potential for biotransfer of pathogens into foods.

Late smoking relapse among adolescent quitters.

Whereas some data are available about late smoking relapse among adult quitters, there are none for teen quitters. This study is a 6-year follow-up of teen quitters (n=253) for whom we collected (retrospectively) data on the extent and timing of relapse. We found that even after a strictly defined quit (six-months prolonged abstinence) at one year, substantial relapse occurred both early and late: the majority (55%) of relapses occurred after the 0-1year interval after having quit. These findings have implication for the need for research into the relapse process for teen quitters, and for the need to develop interventions for teens (as for adults) to prevent (early and) late relapse.

Proactive telephone counseling for adolescent smokers: Comparing regular smokers with infrequent and occasional smokers on treatment receptivity, engagement, and outcomes.

BACKGROUND: Adolescent smoking cessation efforts to date have tended to focus on regular smokers. Consequently, infrequent and occasional smokers' receptivity and response to smoking cessation interventions is unknown. To address this gap, this study examines data from the Hutchinson Study of High School Smoking-a randomized trial that examined the effectiveness of a telephone-delivered smoking cessation intervention for a large, population-based cohort of adolescent smokers proactively recruited in an educational setting. METHODS: The study population included 1837 proactively identified high school smokers. Intervention receptivity, engagement, and outcomes were examined among adolescent infrequent (1-4days/month) and occasional (5-19days/month) smokers and compared with regular smokers (20 or more days/month). RESULTS: With regard to treatment receptivity, intervention recruitment did not differ by smoking frequency. For engagement, intervention completion rates were higher for infrequent smokers (80.5%) compared with occasional (63.8%) and regular smokers (61.5%, p<0.01). Intervention effect sizes were not statistically different across groups. CONCLUSIONS: Adolescent infrequent and occasional smokers are at least as receptive to a proactively delivered smoking cessation intervention as regular smokers and can benefit just as much from it. Including these adolescent smokers in cessation programs and research-with the goal of interrupting progression of smoking before young adulthood-should help reduce the high smoking prevalence among young adults.

Does Effectiveness of Adolescent Smoking-Cessation Intervention Endure Into Young Adulthood? 7-Year Follow-Up Results from a Group-Randomized Trial.

BACKGROUND: The Hutchinson Study of High School Smoking was the first randomized trial to show effectiveness of a smoking cessation intervention on 6-months prolonged smoking abstinence at one year post-intervention in a large population-based sample of adolescent smokers. An important question remains: Do the positive effects from teen smoking cessation interventions seen at up to 12 months post-intervention endure into young adulthood? This study examines for the first time whether such positive early effects from teen smoking cessation intervention can endure into young adulthood in the absence of additional intervention. METHODS: High school smokers (n = 2,151) were proactively recruited into the trial from fifty randomly selected Washington State high schools randomized to the experimental (Motivational Interviewing + Cognitive Behavioral Skills Training telephone counseling intervention) or control (no intervention) condition. These smokers were followed to 7 years post high school to ascertain rates of six-year prolonged smoking abstinence in young adulthood. All statistical tests are two-sided. RESULTS: No evidence of intervention impact at seven years post high school was observed for the main endpoint of six-year prolonged abstinence, neither among all smokers (14.2% in the experimental condition vs. 13.1% in the control condition, difference = +1.1%, 95% confidence interval (CI) = -3.4 to 5.8, p = .61), nor among the subgroups of daily smokers and less-than-daily smokers, nor among other a priori subgroups. But, observed among males was some evidence of an intervention impact on two endpoints related to progress towards quitting: reduction in number of days smoked in the past month, and increase in the length of the longest quit attempt in the past year. CONCLUSIONS: There was no evidence from this trial among adolescent smokers that positive effectiveness of the proactive telephone intervention for smoking abstinence, observed previously at one year post-intervention, was sustained for the long-term into young adulthood. In light of the positive short-term effectiveness consistently observed from this and other trials for teen smokers, together with the lack of evidence from this study that such short-term impact can endure into young adulthood, sustained interventions that continue into young adulthood should be developed and tested for long-term impact. TRIAL REGISTRATION: ClinicalTrials.gov NCT00115882.

One-step dip coating of zwitterionic sulfobetaine polymers on hydrophobic and hydrophilic surfaces.

Zwitterionic sulfobetaine polymers with a catechol chain end (DOPA-PSB) were applied to a variety of hydrophobic polymer sheets and fibers. In addition, a silica surface was tested as a representative hydrophilic substrate. The polymer-coated surfaces showed significantly lower fouling levels than uncoated controls. Because of the anti-polyelectrolyte nature of sulfobetaine zwitterionic polymers, the effect of salt concentration on the coating solutions and the quality of the polymer coating against fouling are studied. The coating method involves only water-based solutions, which is compatible with most surfaces and is environmentally friendly. To demonstrate the versatility of the reported method, we evaluated the fouling levels of the polymer coating on commonly used polymeric surfaces such as polypropylene (PP), polydimethylsiloxane (PDMS), polystyrene (PS), nylon, polyvinyl chloride (PVC), and poly(methyl methacrylate) (PMMA).

Achieving One-step Surface Coating of Highly Hydrophilic Poly(Carboxybetaine Methacrylate) Polymers on Hydrophobic and Hydrophilic Surfaces.

It is highly desirable to develop a universal nonfouling coating via a simple one-step dip-coating method. Developing such a universal coating method for a hydrophilic polymer onto a variety of surfaces with hydrophobic and hydrophilic properties is very challenging. This work demonstrates a versatile and simple method to attach zwitterionic poly(carboxybetaine methacrylate) (PCB), one of the most hydrophilic polymers, onto both hydrophobic and hydrophilic surfaces to render them nonfouling. This is achieved by the coating of a catechol chain end carboxybetaine methacrylate polymer (DOPA-PCB) assisted by dopamine. The coating process was carried out in water. Water miscible solvents such as methanol and tetrahydrofuran (THF) are added to the coatings if surface wettability is an issue, as for certain hydrophobic surfaces. This versatile coating method was applied to several types of surfaces such as polypropylene (PP), polydimethyl siloxane (PDMS), Teflon, polystyrene (PS), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC) and also on metal oxides such as silicon dioxide.

Additive approach for inactivation of Escherichia coli O157:H7, Salmonella, and Shigella spp. on contaminated fresh fruits and vegetables using bacteriophage cocktail and produce wash.

The incidence of foodborne outbreaks involving fresh produce is of worldwide concern. Lytic bacteriophage cocktails and a levulinic acid produce wash were investigated for their effectiveness against the foodborne pathogens Escherichia coli O157:H7, Shigella spp., and Salmonella on broccoli, cantaloupe, and strawberries. Inoculated samples were treated with bacteriophage cocktails (BC) before storage at 10°C for 24 h, a levulinic acid produce wash (PW) after storage at 10°C for 24 h, or a combination of the washes (BCPW) before and after storage. All three treatments were compared against a 200-ppm free available chlorine wash. Wash solutions were prepared using potable water and water with an increased organic content of 2.5 g/liter total dissolved solids and total organic carbon. BCPW was the most effective treatment, producing the highest log reductions in the pathogens. Produce treated with BCPW in potable water with a PW exposure time of 5 min resulted in the highest reduction of each pathogen for all samples tested. The type of produce and wash solution had significant effects on the efficacy of the individual treatments. The chlorine wash in water with higher organic content was the least effective treatment tested. An additive effect of BCPW was seen in water with higher organic content, resulting in greater than 4.0-log reductions in pathogens. Our findings indicate that the combination of antimicrobial BC with a commercial produce wash is a very effective method for treating produce contaminated with E. coli O157:H7, Shigella spp., and Salmonella even in the presence of high loads of organic matter.

Application of a biotin functionalized QD assay for determining available binding sites on electrospun nanofiber membrane.

BACKGROUND: The quantification of surface groups attached to non-woven fibers is an important step in developing nanofiber biosensing detection technologies. A method utilizing biotin functionalized quantum dots (QDs) 655 for quantitative analysis of available biotin binding sites within avidin immobilized on electrospun nanofiber membranes was developed. RESULTS: A method for quantifying nanofiber bound avidin using biotin functionalized QDs is presented. Avidin was covalently bound to electrospun fibrous polyvinyl chloride (PVC 1.8% COOH w/w containing 10% w/w carbon black) membranes using primary amine reactive EDC-Sulfo NHS linkage chemistry. After a 12 h exposure of the avidin coated membranes to the biotin-QD complex, fluorescence intensity was measured and the total amount of attached QDs was determined from a standard curve of QD in solution (total fluorescence vs. femtomole of QD 655). Additionally, fluorescence confocal microscopy verified the labeling of avidin coated nanofibers with QDs. The developed method was tested against 2.4, 5.2, 7.3 and 13.7 mg spray weights of electrospun nanofiber mats. Of the spray weight samples tested, maximum fluorescence was measured for a weight of 7.3 mg, not at the highest weight of 13.7 mg. The data of total fluorescence from QDs bound to immobilized avidin on increasing weights of nanofiber membrane was best fit with a second order polynomial equation (R(2) = .9973) while the standard curve of total fluorescence vs. femtomole QDs in solution had a linear response (R(2) = .999). CONCLUSION: A QD assay was developed in this study that provides a direct method for quantifying ligand attachment sites of avidin covalently bound to surfaces. The strong fluorescence signal that is a fundamental characteristic of QDs allows for the measurement of small changes in the amount of these particles in solution or attached to surfaces.

Social cognitive mediators of adolescent smoking cessation: results from a large randomized intervention trial.

Only one prior study has examined why adolescent smoking cessation interventions are effective. To address this understudied and important issue, we examined whether a large adolescent smoking cessation intervention trial's outcomes were mediated by social cognitive theory processes. In a randomized trial (N = 2,151), counselors proactively delivered a telephone intervention to senior year high school smokers. Mediators and smoking status were self-reported at 12-months postintervention eligibility (88.8% retention). At least 6-months abstinence was the outcome. Among all enrolled smokers, increased self-efficacy to resist smoking in (a) social and (b) stressful situations together statistically mediated 55.6% of the intervention's effect on smoking cessation (p < .001). Among baseline daily smokers, increased self-efficacy to resist smoking in stressful situations statistically mediated 56.9% of the intervention's effect (p < .001). Self-efficacy to resist smoking is a possible mediator of the intervention's effect on smoking cessation.

Telephone-delivered Acceptance and Commitment Therapy for adult smoking cessation: a feasibility study.

BACKGROUND: Quitline smoking cessation counseling results in a mere 12% success rate. Testing of new telephone-delivered cessation counseling approaches is needed. OBJECTIVE: Determine the feasibility of the first telephone-delivered Acceptance and Commitment Therapy (ACT) intervention for smoking cessation. DESIGN: Fourteen adults (57% racial/ethnic minority, 8/14) in a single-arm study. Counselor proactively delivered a 5-session (90-min total) ACT telephone intervention for smoking cessation. Hypothesized ACT processes were self-reported at baseline and posttreatment. Smoking status was self-reported at baseline, 20-day posttreatment (93% retention, 13/14), and 12-month posttreatment (93% retention, 13/14). RESULTS: (a) Delivery length and duration: average of 3.5 calls and 81.9-min intervention duration. (b) Receptivity: 100% (14/14) felt respected by the counselor, 86% (12/14) said that intervention was a good fit, and 93% (13/14) said that intervention helped them quit. (c) ACT processes: (i) acceptance of physical cravings, emotions, and thoughts that cue smoking increased from baseline to posttreatment (p = .001, p = .038, and p = .085, respectively) and (ii) commitment to quitting increased from baseline to posttreatment (p = .01). (4) Intent-to-treat cessation outcomes: (i) at 20-day posttreatment, 43% (6/14) had not smoked the day of the survey and 29% (4/14) had not smoked in past 7 days and (ii) at 12-month posttreatment, 29% (4/14) had not smoked at all in past 12 months. These quit rates are over double the 12% quit rates of current standard telephone counseling. CONCLUSION: Telephone-delivered ACT shows promise for smoking cessation and warrants future testing in a well-powered randomized trial.

Group-randomized trial of a proactive, personalized telephone counseling intervention for adolescent smoking cessation.

BACKGROUND: The Hutchinson Study of High School Smoking randomized trial was designed to rigorously evaluate a proactive, personalized telephone counseling intervention for adolescent smoking cessation. METHODS: Fifty randomly selected Washington State high schools were randomized to the experimental or control condition. High school junior smokers were proactively identified (N = 2151). Trained counselors delivered the motivational interviewing plus cognitive behavioral skills training telephone intervention to smokers in experimental schools during their senior year of high school. Participants were followed up, with 88.8% participation, to outcome ascertainment more than 1 year after random assignment. The main outcome was 6-months prolonged abstinence from smoking. All statistical tests were two-sided. RESULTS: The intervention increased the percentage who achieved 6-month prolonged smoking abstinence among all smokers (21.8% in the experimental condition vs 17.7% in the control condition, difference = 4.0%, 95% confidence interval [CI] = -0.2 to 8.1, P = .06) and in particular among daily smokers (10.1% vs 5.9%, difference = 4.1%, 95% CI = 0.8 to 7.1, P = .02). There was also generally strong evidence of intervention impact for 3-month, 1-month, and 7-day abstinence and duration since last cigarette (P = .09, .015, .01, and .03, respectively). The intervention effect was strongest among male daily smokers and among female less-than-daily smokers. CONCLUSIONS: Proactive identification and recruitment of adolescents via public high schools can produce a high level of intervention reach; a personalized motivational interviewing plus cognitive behavioral skills training counseling intervention delivered by counselor-initiated telephone calls is effective in increasing teen smoking cessation; and both daily and less-than-daily teen smokers participate in and benefit from telephone-based smoking cessation intervention.

Design and implementation of an effective telephone counseling intervention for adolescent smoking cessation.

BACKGROUND: Effective smoking cessation for youth is urgently needed, but the literature guiding such efforts is nascent. We evaluated the implementation of a proactive intervention for adolescent smoking cessation that incorporated motivational interviewing (MI) and cognitive behavioral skills training (CBST). METHODS: We proactively identified 1058 smokers via classroom survey of enrolled juniors in 25 experimental high schools. After parental consent was obtained, trained counselors telephoned participants to invite their participation and deliver personalized smoking cessation counseling that combined MI and CBST. Implementation quality was assessed via weekly supervision of counselors, monitoring of counselor adherence to protocol via review of 5% of each counselor's calls, and formal evaluation of counselor fidelity to MI via review of a random sample of 19.8% of counseling calls using the Motivational Interviewing Treatment Integrity Code. RESULTS: Among identified smokers, 948 (89.6%) were eligible for intervention by age (> or =18 years) or parental consent, 736 (70%) agreed to participate in telephone counseling, 691 (65%) completed one or more counseling calls, and 499 (47%) completed all planned calls. Telephone delivery of the personalized MI and CBST counseling intervention to a general population of adolescents was done with greater than 90% adherence to the intervention protocol. Review of the random sample of counselors' calls demonstrated that more than 85% of counselors' calls met or exceeded benchmark scores for four of six evaluated behaviors: MI spirit (99.1%), empathy (96.2%), ratio of reflections to questions (97.2%), and MI adherent (85.7%). CONCLUSION: An effective proactive telephone counseling intervention consisting of MI and CBST can be successfully implemented with reach and fidelity in a general population of adolescent smokers.

Membrane permeability and antimicrobial kinetics of cecropin P1 against Escherichia coli.

The interaction of cecropin P1 (CP1) with Escherichiacoli was investigated to gain insight into the time-dependent antimicrobial action. Biophysical characterizations of CP1 with whole bacterial cells were performed using both fluorescent and colorimetric assays to investigate the role of membrane permeability and lipopolysaccharide (LPS) binding in lytic behavior. The kinetics of CP1 growth inhibition assays indicated a minimal inhibitory concentration (MIC) of 3 microM. Bactericidal kinetics at the MIC indicated rapid killing of E.coli (<30 min). Membrane permeability studies illustrated permeation as a time-dependent event. Maximum permeability at the MIC occurred within 30 min, which correlates to the bactericidal action. Further investigation showed that the immediate permeabilizing action of CP1 is concentration-dependent, which correlates to the concentration-dependent nature of the inhibition assays. At the MIC and above, the immediate permeability was significant enough that the cells could not recover and exhibit growth. Below the MIC, immediate permeability was evident, but the level was insufficient to inhibit growth. Dansyl polymyxin B displacement studies showed LPS binding is essentially the same at all concentrations investigated. However, it does appear that only the immediate interaction is important, because binding continued to increase over time beyond cell viability. Our studies correlated CP1 bactericidal kinetics to membrane permeability suggesting CP1 concentration-dependent killing is driven by the extent of the immediate permeabilizing action of the peptide.

Addressing challenges in adolescent smoking cessation: design and baseline characteristics of the HS Group-Randomized trial.

OBJECTIVE: Well-documented challenges have hampered both intervention development and research in teen smoking cessation. Addressing these challenges, the Hutchinson Study of High School Smoking (HS Study), the largest group-randomized trial in adolescent smoking cessation to date, incorporates several design innovations to investigate the effect of a counselor-initiated, individually tailored telephone counseling smoking cessation intervention for older adolescents. This paper presents and discusses these innovative design features, and baseline findings on the resulting study population. METHOD: The trial used a population-based survey to proactively identify and recruit all high school juniors who had smoked in the past month - potentially expanding intervention reach to all smokers, even those who smoked less than daily and those not motivated to quit. For ethical and intervention reasons, some nonsmokers were enrolled in the intervention, also. Other important design features included the random allocation of schools into experimental conditions (intervention vs. no-intervention control) and a multi-wave design. RESULTS AND CONCLUSION: The design innovations address problems and challenges identified in adolescent smoking cessation literature. The heterogeneous baseline characteristics of the study population, well-balanced between the two arms, have three significant implications: They (1) demonstrate the effectiveness of the trial's design features, (2) highlight several intervention-related issues, and (3) provide assurance that the trial's evaluation of intervention effectiveness will be unbiased.

Overcoming barriers to recruitment and retention in adolescent smoking cessation.

Participant recruitment and retention have been identified as challenging aspects of adolescent smoking cessation interventions. Problems associated with low recruitment and retention include identifying smokers, obtaining active parental consent, protecting participants' privacy, respecting participants' autonomy, and making participation relevant and accessible to adolescents. This paper describes nine strategies for minimizing these recruitment and retention problems via a proactive telephone counseling intervention, and reports on their simultaneous implementation among 1,058 smokers from 25 high schools in Washington state. Results are as follows: (a) 85.9% of parents of minor-age seniors provided active consent for their teen's participation, (b) 89.8% of eligible smokers were successfully contacted by counselors, (c) 86.5% of contacted smokers consented to participate in the cessation counseling, (d) 93.8% of consented smokers participated in smoking cessation counseling calls, and (e) 72.2% of participating smokers completed their full intervention. These results demonstrate that older teens who smoke, and their parents, are receptive to confidential cessation counseling that is personally tailored, supportive of their autonomy, and proactively delivered via the telephone.

Inactivation of escherichia coli O157:H7 in cattle drinking water by sodium caprylate.

Escherichia coli O157:H7 is an important foodborne pathogen. Cattle serve as one of the major reservoirs of E. coli O157:H7, excreting the pathogen in feces. Environmental persistence of E. coli O157:H7 is critical in its epidemiology on farms, and the pathogen has been isolated from cattle water troughs. Thus, there is a need for an effective method for killing E. coli O157:H7 in cattle drinking water. In this study, the efficacy of sodium caprylate for killing E. coli O157:H7 in cattle drinking water was investigated. A four-strain mixture of E. coli O157:H7 was inoculated (6.0 log CFU/ml) into 100-ml samples of well water containing 0, 75, 100, or 120 mM sodium caprylate. Water samples containing 1% (wt/vol) bovine feces or feed also were included. The samples were incubated at 21 or 8 degrees C for 21 days. Water samples were analyzed for viable E. coli O157:H7 on days 0, 1, 3, 5, and 7 and weekly thereafter. Triplicate samples of each treatment and control were included, and the study was repeated twice. The magnitude of E. coli O157:H7 inactivation in water significantly increased (P < 0.01) with increases in caprylate concentration and storage temperature. At 120 mM, sodium caprylate completely inactivated E. coli O157:H7 in all the samples after 1 to 20 days, depending on the treatments. The presence of feces or feed also had a significant effect (P < 0.01) on the antibacterial property of caprylate; the presence of feces decreased the antibacterial effect, whereas addition of feed enhanced the effect. These results indicate that sodium caprylate is effective in killing E. coli O157:H7 in cattle drinking water, but detailed cattle palatability studies of water containing caprylate are necessary.

Nine-year prediction of adolescent smoking by number of smoking parents.

For scientific and public health reasons, it is important to identify the role of family influences on child smoking acquisition. Using a well-followed (>90%) cohort of 3,012 children and their parents, this study prospectively investigated the influence of smoking by 0 vs. 1 vs. 2 parents when the children were young (3rd grade), on whether the children subsequently became daily smokers. It is the only study to investigate the prediction of child/adolescent smoking at the end of the smoking acquisition period (12th grade) by parental smoking at the start of the period (3rd grade). Logistic regression analyses revealed that having one parent who smokes substantially increases the risk that children will become daily smokers, relative to families where neither parent smokes (OR=1.90, p<.01). There is no evidence that the increased risk depends on parent or child gender. These results suggest the need for public health interventions that inform parents of young children that their own smoking behavior increases their children's risk for future smoking.

Survival and growth characteristics of Escherichia coli O157:H7 in pasteurized and unpasteurized Cheddar cheese whey.

The objective of this study was to determine the survival and growth characteristics of Escherichia coli O157:H7 in whey. A five-strain mixture of E. coli O157:H7 was inoculated into 100 ml of fresh, pasteurized or unpasteurized Cheddar cheese whey (pH 5.5) at 10(5) or 10(2) CFU/ml, and stored at 4, 10 or 15 degrees C. The population of E. coli O157:H7 (on Sorbitol MacConkey agar supplemented with 0.1% 4-methylumbelliferyl-beta-D-glucuronide) and lactic acid bacteria (on All Purpose Tween agar) were determined on days 0, 1, 4, 7, 14, 21 and 28. At all storage temperatures, survival of E. coli O157:H7 was significantly higher (P<0.01) in the pasteurized whey compared to that in the unpasteurized samples. At 10 and 15 degrees C, E. coli O157:H7 in pasteurized whey significantly (P<0.05) increased during the first week of storage, followed by a decrease thereafter. However at the same temperatures, E. coli O157:H7 exhibited a steady decline in the unpasteurized samples from day 0. At 4 degrees C, E. coli O157:H7 did not grow in pasteurized and unpasteurized whey; however, the pathogen persisted longer in pasteurized samples. At all the three storage temperatures, E. coli O157:H7 survived up to day 21 in the pasteurized and unpasteurized whey. The initial load of lactic acid bacteria in the unpasteurized whey samples was approximately 7.0 log10 CFU/ml and, by day 28, greater than 3.0 log10 CFU/ml of lactic acid bacteria survived in unpasteurized whey at all temperatures, with the highest counts recovered at 4 degrees C. Results indicate the potential risk of persistence of E. coli O157:H7 in whey in the event of contamination with this pathogen.