Induction of ß-Lactamase Activity and Decreased ß-Lactam Susceptibility by CO2 in Clinical Bacterial Isolates.

Antimicrobial susceptibility testing of clinical isolates is a crucial step toward appropriate treatment of infectious diseases. The clinical isolate Francisella philomiragia 14IUHPL001, recently isolated from a 63-year-old woman with atypical pneumonia, featured decreased susceptibility to ß-lactam antibiotics when cultivated in 5% CO2. Quantitative ß-lactamase assays demonstrated a significant (P < 0.0001) increase in enzymatic activity between bacteria cultivated in 5% CO2 over those incubated in ambient air. The presence of ß-lactamase genes blaTEM and blaSHV was detected in the clinical isolate F. philomiragia 14IUHPL001 by PCR, and the genes were positively identified by nucleotide sequencing. Expression of blaTEM and blaSHV was detected by reverse transcription-PCR during growth at 5% CO2 but not during growth in ambient air. A statistically significant alkaline shift was observed following cultivation of F. philomiragia 14IUHPL001 in both ambient air and 5% CO2, allowing desegregation of the previously reported effects of acidic pH from the currently reported effect of 5% CO2 on blaTEM and blaSHV ß-lactamases. To ensure that the observed phenomenon was not unique to F. philomiragia, we evaluated a clinical isolate of blaTEM-carrying Haemophilus influenzae and found parallel induction of blaTEM gene expression and ß-lactamase activity at 5% CO2 relative to ambient air. IMPORTANCE ß-Lactamase induction and concurrent ß-lactam resistance in respiratory tract pathogens as a consequence of growth in a physiologically relevant level of CO2 are of clinical significance, particularly given the ubiquity of TEM and SHV ß-lactamase genes in diverse bacterial pathogens. This is the first report of ß-lactamase induction by 5% CO2.

Differential Evolutionary Selection and Natural Evolvability Observed in ALT Proteins of Human Filarial Parasites.

The abundant larval transcript (ALT-2) protein is present in all members of the Filarioidea, and has been reported as a potential candidate antigen for a subunit vaccine against lymphatic filariasis. To assess the potential for vaccine escape or heterologous protection, we examined the evolutionary selection acting on ALT-2. The ratios of nonsynonymous (K(a)) to synonymous (K(s)) mutation frequencies (ω) were calculated for the alt-2 genes of the lymphatic filariasis agents Brugia malayi and Wuchereria bancrofti and the agents of river blindness and African eyeworm disease Onchocerca volvulus and Loa loa. Two distinct Bayesian models of sequence evolution showed that ALT-2 of W. bancrofti and L. loa were under significant (P<0.05; P < 0.001) diversifying selection, while ALT-2 of B. malayi and O. volvulus were under neutral to stabilizing selection. Diversifying selection as measured by ω values was notably strongest on the region of ALT-2 encoding the signal peptide of L. loa and was elevated in the variable acidic domain of L. loa and W. bancrofti. Phylogenetic analysis indicated that the ALT-2 consensus sequences formed three clades: the first consisting of B. malayi, the second consisting of W. bancrofti, and the third containing both O. volvulus and L. loa. ALT-2 selection was therefore not predictable by phylogeny or pathology, as the two species parasitizing the eye were selected differently, as were the two species parasitizing the lymphatic system. The most immunogenic regions of L. loa and W. bancrofti ALT-2 sequence as modeled by antigenicity prediction analysis did not correspond with elevated levels of diversifying selection, and were not selected differently than predicted antigenic epitopes in B. malayi and O. volvulus. Measurements of ALT-2 evolvability made by χ2 analysis between alleles that were stable (O. volvulus and B. malayi) and those that were under diversifying selection (W. bancrofti and L. loa) indicated significant (P<0.01) deviations from a normal distribution for both W. bancrofti and L. loa. The relationship between evolvability and selection in L. loa followed a second order polynomial distribution (R2 = 0.89), indicating that the two factors relate to one another in accordance with an additional unknown factor. Taken together, these findings indicate discrete evolutionary drivers acting on ALT-2 of the four organisms examined, and the described variation has implications for design of novel vaccines and diagnostic reagents. Additionally, this represents the first mathematical description of evolvability in a naturally occurring setting.

Impact of fatigue on performance in registered nurses: data mining and implications for practice.

Performance of nurses has a direct effect on the quality and safety of care that is delivered. Fatigue has been identified as a factor that leads to performance decrements in healthcare workers, especially nurses. Determining associations between dimensions of fatigue and performance is imperative to better understanding fatigue in nurses and the potential implications for both patient and provider safety. This article identifies associations between ranges of fatigue levels and significant differences in perceived performance, and analyzes interactions between fatigue dimensions in relation to perceived performance scores. Overall, mental fatigue tended to have higher perceived performance decrements than physical and total fatigue in the highest fatigue ranges. As physical fatigue begins to develop in nurses, physical exertion rather than discomfort is more critical to perceived performance. As acute fatigue levels increase, perceived performance levels continue to decrease, whereas the role of chronic fatigue is relatively constant. Minimizing the development of acute fatigue may help in maintaining higher performance levels. The findings from this study provide valuable information in quantifying the changes in perceived performance with regard to specific fatigue levels, as well as an initial understanding of how the individual dimensions and states of fatigue vary in their association with perceived performance decrements.

The effects of fatigue on performance in simulated nursing work.

Fatigue is associated with increased rates of medical errors and healthcare worker injuries, yet existing research in this sector has not considered multiple dimensions of fatigue simultaneously. This study evaluated hypothesised causal relationships between mental and physical fatigue and performance. High and low levels of mental and physical fatigue were induced in 16 participants during simulated nursing work tasks in a laboratory setting. Task-induced changes in fatigue dimensions were quantified using both subjective and objective measures, as were changes in performance on physical and mental tasks. Completing the simulated work tasks increased total fatigue, mental fatigue and physical fatigue in all experimental conditions. Higher physical fatigue adversely affected measures of physical and mental performance, whereas higher mental fatigue had a positive effect on one measure of mental performance. Overall, these results suggest causal effects between manipulated levels of mental and physical fatigue and task-induced changes in mental and physical performance. STATEMENT OF RELEVANCE: Nurse fatigue and performance has implications for patient and provider safety. Results from this study demonstrate the importance of a multidimensional view of fatigue in understanding the causal relationships between fatigue and performance. The findings can guide future work aimed at predicting fatigue-related performance decrements and designing interventions.

Fatigue, performance and the work environment: a survey of registered nurses.

AIMS: This paper is a report of a study of perceived levels of mental, physical and total fatigue, and also acute and chronic fatigue states, among registered nurses. Relationships between dimensions of fatigue and performance were investigated, as were differences in fatigue across levels of several demographic and work environment variables. BACKGROUND: Fatigue is a factor that has been linked to performance decrements in healthcare workers. As a result of the nature of their work, nurses may be particularly susceptible to multiple dimensions of fatigue, and their performance is closely linked to patient safety. METHODS: An online survey was used to measure mental, physical, and total fatigue dimensions, acute and chronic fatigue states, and performance. Participants were recruited via convenience sampling in cooperation with professional nursing organizations; 745 registered nurses completed the survey between February 2008 and April 2009. RESULTS: Reported mental fatigue levels were higher than physical fatigue levels, and acute fatigue levels were higher than chronic fatigue levels. All fatigue dimensions and states were negatively correlated with perceived performance. Longer shift lengths and hours worked per week were associated with increases in physical and total fatigue levels. Mental, physical and total fatigue levels also differed with shift schedule. CONCLUSIONS: Fatigue levels were negatively correlated with performance, further supporting the role of fatigue in nurse performance. Work environment variables were strongly associated with differences in perceived levels of fatigue. By altering the work environment, it may thus be possible to reduce fatigue levels and the rates of medical errors.

Effects of two hospital bed design features on physical demands and usability during brake engagement and patient transportation: a repeated measures experimental study.

BACKGROUND: Work-related musculoskeletal disorders (WMSDs) are prevalent among healthcare workers worldwide. While existing research has focused on patient-handling techniques during activities which require direct patient contact (e.g., patient transfer), nursing tasks also involve other patient-handling activities, such as engaging bed brakes and transporting patients in beds, which could render healthcare workers at risk of developing WMSDs. OBJECTIVES: Effectiveness of hospital bed design features (brake pedal location and steering-assistance) was evaluated in terms of physical demands and usability during brake engagement and patient transportation tasks. DESIGN: Two laboratory-based studies were conducted. In simulated brake engagement tasks, three brake pedal locations (head-end vs. foot-end vs. side of a bed) and two hands conditions (hands-free vs. hands-occupied) were manipulated. Additionally, both in-room and corridor patient transportation tasks were simulated, in which activation of steering-assistance features (5th wheel and/or front wheel caster lock) and two patient masses were manipulated. PARTICIPANTS: Nine novice participants were recruited from the local student population and community for each study. METHODS: During brake engagement, trunk flexion angle, task completion time, and questionnaires were used to quantify postural comfort and usability. For patient transportation, dependent measures were hand forces and questionnaire responses. RESULTS: Brake pedal locations and steering-assistance features in hospital beds had significant effects on physical demands and usability during brake engagement and patient transportation tasks. Specifically, a brake pedal at the head-end of a bed increased trunk flexion by 74-224% and completion time by 53-74%, compared to other pedal locations. Participants reported greater overall perceived difficulty and less postural comfort with the brake pedal at the head-end. During in-room transportation, participants generally reported "Neither Low nor High" physical demands with the 5th wheel activated, compared to "Moderately High" physical demands when the 5th wheel was deactivated. Corridor transportation was similarly reported to be easier when a steering-assistance feature (the 5th wheel or front caster lock) was activated. CONCLUSIONS: Braking and steering-assistance features of hospital beds can have important effects on task efficiency and physical demands placed on healthcare workers. Selection of specific designs may thus be able to improve productivity and contribute to a reduction in WMSDs risk among healthcare workers.

Human factors in the development and implementation of telerehabilitation systems.

Telemedicine services must be designed and implemented with the users in mind. When conducting telerehabilitation, factors such as age, education and technology experience must be taken into account. In addition, telerehabilitation must also accommodate a range of potential patient impairments, including deficits in language, cognition, motor function, vision and voice. Telerehabilitation technology and treatment environments should adhere to universal design standards so as to be accessible, efficient, usable and understandable to all. This will result in improved access to a wider range of telerehabilitation services that will facilitate and enhance the rehabilitative treatment and recovery of people living with varying levels of injury, impairment and disability.

Sources of error in computerized neuropsychological assessment.

Computerized neuropsychological assessment has integrated slowly into research and practice since the introduction of the personal computer. Though initial integration of technology to the laboratory and clinical setting utilized specialized hardware and software, newer generation assessment tools are integrated with "off-the-shelf" operating systems. Further, neuropsychological assessment is beginning to find Internet-based application for remote assessment. As these applications are more broadly applied, it is essential to understand potential errors that can be created both in test administration and in reaction time measurement due to hardware and software interactions. In this article, user considerations are specifically addressed for resident and Internet-enabled assessment software. Potential hardware and software conflicts are defined and potential remediation is suggested. Computerized assessment is a valuable tool for neuropsychologists as long as it is used responsibly with an understanding of the potential technical complications.

The effect of videoconference-based telerehabilitation on story retelling performance by brain-injured subjects and its implications for remote speech-language therapy.

This paper presents results from a study conducted at the Rehabilitation Engineering Research Center (RERC) on Telerehabilitation at the National Rehabilitation Hospital. The study was designed to measure performance by brain-injured subjects, with medical diagnoses of stroke or traumatic brain injury, on a standardized Speech-Language Pathology evaluation conducted in both face-to-face and videoconference-based telerehabilitation settings. The Story Retelling Procedure (SRP), which measures connected language production and comprehension of spoken narratives, was administered to each subject in both settings. The primary objectives of this study were to: (1) compare communication as measured by the SRP between experimental settings, and (2) determine if subject variables (such as age, education, technology experience or gender) had an effect on performance differences between settings. The rationale was that any difference in this aspect of performance must be identified and characterized before this mode of intervention can be used clinically. Across all subjects (n = 40), no significant difference (p > 0.05) was found between SRP performance measured in the two settings. Additionally, variables including age, education, technology experience, and gender did not significantly affect the difference between performance in the two settings. Overall, subjects reported a high level of acceptance of videoconferencing with 34 subjects responding "yes," 4 responding "no," and 2 responding "maybe" when asked if they would use videoconferencing again to talk to a clinician. Results of this study confirm the potential for SLP treatment using videoconferencing and indicate a need for continued research in the field.