Airborne pathogenic bacteria can present a significant public health risk. Pathogenic Listeria monocytogenes can colonize numerous surfaces as well, through direct and indirect cross contamination. The physical environment can also affect the transmission and viability of Listeria (distance from the source, temperature, humidity, air flow). The purpose of this work was to explore the ability of Listeria innocua (a surrogate for L. monocytogenes) to contaminate a surface after it has become aerosolized in a bioaerosol chamber and a walk-in cooler. L. innocua was nebulized into a 154 L biosafety chamber (~5 log CFU in 1 mL) at two relative humidity (RH) levels (83% and 65%). Oxford Listeria agar plates, stainless steel coupons and polyethylene (HDPE) coupons in the chamber were exposed to the aerosolized bacteria for 5, 10, 20 or 40 minutes. Also, at these times, air samples (100 L) were collected on to gelatin filters which were transferred to Oxford agar plates. In the second part of the research, L. innocua was nebulized into an 11 m3 walk-in cooler where RH ranged from ~29-37%. Aerosolized bacteria were collected on to Oxford agar plates for 10 min intervals and with 50 or 100 L air samples. Recovery of L. innocua from steel, plastic and agar was significantly higher at 83% RH (2.7 cells/cm2) compared to 65% RH (0.45 cells/cm2). Mean cell recovery from air samples (gelatin filters) was significantly higher (p<0.05) when collected 5 or 10 minutes after nebulization at 83% humidity (mean 2.2 CFU/L) compared to collection after 20 or 40 minutes or compared to all times under 65% humidity (mean 0.4 CFU/L). Recovery from HDPE coupons (1.21 CFU/cm2) was 2.5 X recovery from Oxford agar (0.49 CFU/cm2). In the walk-in cooler, total estimated mean recovery from Oxford media at 10 min after nebulizing was 0.48%, but only 0.04% for samples collected after 60 minutes. The recovery of L. innocua from air samples after 60 min was one-fourth of the number recovered 5 min after nebulizing. No significant difference in recovery was found between plates at different distances (2 – 2.5 m) from the nebulizer in the walk-in cooler. Understanding the survival of aerosolized Listeria and how it can colonize over time on a food contact surface will enhance our efforts to prevent transmission on a small and large scale. The food industry will be able to implement better safety measures to prevent contamination by Listeria species. / Ph. D.

The primary clinical characteristics of cystic fibrosis (CF) are malnutrition caused by malabsorption secondary to pancreatic insufficiency, chronic pulmonary infections, and male infertility. The major cause of morbidity and mortality are bronchiectasis and obstructive pulmonary disease. Lung disease in CF is manifested by this chronic lung disease progression, with intermittent episodes of acute worsening of symptoms called pulmonary exacerbations. Once the patient has stabilized, and if suitable care can be arranged, these interventions are often transitioned to the home. This review summarizes important points pertinent to the use of intravenous and inhaled antimicrobials that may be encountered by prescribers, nurses, technicians, and case managers in the home health setting. Appropriate dosing, indications, adverse drug reactions, monitoring parameters, and practicality of both intravenous and inhaled antimicrobials are discussed.

This research integrates the theoretical implications of risk perception, the social amplification of risk, and the role of place-specific contexts, in order to explore the various perceptions surrounding Florida red tides. Florida red tides are a naturally-occurring event, yet most scientists agree that they are increasing in frequency, duration, and severity. This has profound implication for public health, the local economy, and the biological community. While many of the negative impacts are not easily controllable at this time, some of the secondary impacts can be mitigated through individuals' responses. Unfortunately, public perceptions and consequent reactions to red tides have not been investigated. This research uses questionnaire surveys, semi-structured interviews, and newspaper content analysis to explore the various perceptions of risk surrounding red tides. Surveys and interviews were conducted along two Florida west coast beaches, Fort De Soto Park and Siesta Key. Results indicate that the underlying foundations of the social amplification of risk framework are applicable to understanding how individuals form perceptions of risk relative to red tide events. There are key differences between the spatial locations of individuals and corresponding perceptions, indicating that place-specific contexts are essential to understanding how individuals receive and interpret risk information. The results also suggest that individuals may be lacking efficient and up-to-date information about red tides and their impacts due to inconsistent public outreach. Overall, particular social and spatial factors appear to be more influential as to whether individuals amplify or attenuate the risks associated with red tides.

Vocal fold hydration is important for efficient oscillation during voice production. Dehydration of the vocal fold surface is believed to produce adverse effects on the voice. Specifically, low environmental humidity, mouth breathing, and certain medical conditions may contribute to laryngeal and vocal fold dehydration. This dehydration effect may be quantified using the observed pressure and flow at the onset of phonation, operationally defined as phonation threshold pressure (PTP) and phonation threshold flow (PTF), respectively. Previous research has documented that nebulized isotonic saline (0.9% Na+Cl-) can reduce PTP. Additionally, the topical application of liquid saline increases vocal fold hydration in excised larynx studies. However, no studies have examined the prevention of vocal fold dehydration using aerosolized saline in an excised larynx mechanical model. The purpose of the current investigation was to determine the preventive effects of aerosolized isotonic saline in a physiologically realistic excised larynx model. Using a prospective, mixed experimental design with a control group, five bench-mounted, excised porcine larynges received 4-min doses of aerosolized saline delivered supraglottally for a total of 24 min. Subsequently, larynges received 1-min doses of desiccated air (<1% relative humidity) delivered supraglottally. A control group of five porcine larynges received only desiccated air. Phonation was attempted following each dose of aerosolized saline or desiccated air. The desiccation doses were repeated for both groups until the larynges were no longer able to phonate. The PTP and PTF were measured at baseline and following each dose of aerosolized saline or desiccated air. Analysis of the results indicated that aerosolized saline significantly delayed the adverse effects of vocal fold dehydration based on the total number of desiccation doses required to cease phonation for experimental versus control groups (p = .002). Trends demonstrated that PTP decreased after aerosolized saline and increased during desiccation trials. The PTF trends were similar during desiccation. The results from this study indicate that aerosolized saline may be used prophylactically to prevent vocal fold dehydration. These findings offer important advances in vocal fold hydration theory and dehydration prevention in a physiologically realistic excised mechanical model.

Previous studies have found vocal fold hydration to be crucial for healthy function of the vocal mechanism. Surface tissue hydration facilitates efficient vocal fold oscillation. The composition of vocal fold surface fluid includes protective water and mucus layers, similar to the fluid that covers the mucosa and epithelia of the upper airway. Laryngeal dehydration has been linked to several factors such as mouth breathing, obstructive sleep apnea, dry air exposure, upper airway hypersensitivity, and certain diseases or behavioral voice use factors. Laryngeal dehydration affects phonation threshold pressure (PTP) and phonation threshold flow (PTF), defined as the pressure and flow observed at the onset of phonation, respectively. The application of topical nebulized isotonic saline (0.9% Na+Cl-) has been shown in previous work to decrease PTP. However, there are no studies examining the effects of aerosolized saline, administered supraglottally, on dehydrated excised porcine larynges. Examining the effects of aerosolized saline in an excised model is essential to determine any independent effects of this treatment in the absence of other physiologic mechanisms such as mucus secretion. This study sought to investigate the effects of aerosolized saline on dehydrated animal vocal folds to determine if the administration of supraglottic aerosolized saline, via a nebulizer, could reverse the adverse effects of laryngeal dehydration. The study included a prospective, mixed experimental design with two groups, one desiccation/aerosolization (A/B) group and a control (A) group, each comprised of five bench-mounted porcine larynges. Larynges in both groups received desiccated air (<1% relative humidity) supraglottally via custom tubing for 1-min doses until the vocal folds ceased audible phonation. Following the desiccation challenge, the A/B group received 2-min doses of aerosolized isotonic saline until phonation began again. The PTP and PTF were measured during phonation trials following each dose of the desiccation or aerosolization treatment. Significant changes in PTP and PTF were observed following both the dehydration and aerosolization treatment. The PTP increased significantly following the dehydration challenge and returned near baseline following the aerosolization treatment. The results of this investigation supported the hypothesis that the administration of aerosolized saline may reverse the adverse effects of vocal fold dehydration. Moreover, in a more physiologically realistic excised model, applying the mechanics of respiration, this study advanced the development of innovative theories related to the reversal of the adverse effects of dehydration, which may prevent the development of voice disorders.

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