Survival of Salmonella enterica subsp. enterica serovar Javiana and Listeria monocytogenes is dependent on type of soil-free microgreen cultivation matrix.

AIMS: This study measured the survival of Listeria monocytogenes and Salmonella enterica subsp. enterica serovar Javiana over a 10-day period on four soil-free cultivation matrix (SFCM) types in the absence of microgreens and fertilizers. METHODS AND RESULTS: Coco coir (CC), a Sphagnum peat/vermiculite mix, Biostrate® and hemp mat samples were inoculated with 3 × 106  CFU per ml bacteria, incubated at room temperature, and analysed on day 0, 1, 3, 6, and 10. Statistically significant differences in pathogen survival were observed across multiple time points for hemp and Biostrate compared to CC, peat and bacteria in phosphate buffered saline (PBS) (P < 0·05). S. Javiana showed greater overall survival compared to Listeria (P < 0·0002). By day 10, S. Javiana persisted at the initial inoculum concentration for hemp and Biostrate while declining by 1-2 log CFU per ml in CC, peat and PBS. Listeria also persisted at the initial concentration in hemp and Biostrate but decreased to 1 log CFU per ml in peat and below the detection limit in CC and PBS. CONCLUSIONS: Overall, there are survival differences between bacterial pathogens in SFCM used in microgreen production systems. To our knowledge, this is the first comparison of survival among SFCM involving a S. enterica serovar and L. monocytogenes, and the first study comparing CC, Biostrate and hemp. SIGNIFICANCE AND IMPACT OF THE STUDY: Microgreens production systems predominantly utilize soil alternatives, and it is not well-understood how pathogen transmission risk may be affected by the type of SFCM. The results of this study impact the microgreen industry as media selection may be used to reduce the risk of bacterial pathogen proliferation and transmission to the plant potentially resulting in potential foodborne illness.

Key characteristics of foods with an elevated risk for viral enteropathogen contamination.

Viral enteropathogens are one of the leading causative agents of foodborne illnesses in both the United States and the European Union. While human noroviruses and hepatitis A virus cause the vast majority of outbreaks and illnesses, there are handful of human enteric viruses that contribute to sporadic outbreaks worldwide including astrovirus, sapovirus, rotavirus, enterovirus and Aichi virus. In addition, hepatitis E virus is increasingly being recognized as an emerging zoonotic threat within the food supply. This review aims to briefly describe the primary human enteric viruses of concern with respect to foodborne transmission. Next, we focus on the contamination and persistence of these viruses within three high-risk food commodities-leafy greens, soft red fruits and bivalve mollusks. As opposed to detailing the specific routes by which these foods can be contaminated with enteric viruses, we have chosen to focus on their persistence and specific interactions within the food itself. Therefore, the processes of attachment and internalization of the viruses in foods have been emphasized. Looking forward, the implications of these specific interactions of human enteric viruses with leafy greens, soft red fruits and bivalve mollusks are briefly considered within the context of future prevention and control strategies.

Physicochemical stability profile of Tulane virus: a human norovirus surrogate.

AIMS: Human norovirus (HuNoV) is estimated to cause 19-21 million illnesses each year in the US. A major limitation in HuNoV research is the lack of an in vitro culture system; therefore, surrogate viruses including murine norovirus (MNV) and feline calicivirus (FCV) are used to study HuNoV. Here, we aim to establish the physiochemical properties of Tulane virus (TV)­a newer HuNoV surrogate. METHODS AND RESULTS: For thermal inactivation, TV was exposed to 37°C for 2 h, and 56, 63 and 72°C for 30 min. For ethanol tolerance, TV was treated with 60, 70 and 90% ethanol at room temperature (RT) for 5 min. Tulane virus pH stability at pH 2, 3, 7, 9 and 10 was performed at RT for 90 min. At 37°C, there was no significant reduction in TV after 2 h. However, at 56, 63 and 72°C, D-values of 4·03, 1·18, and 0·24 min, were calculated respectively. The D-values obtained for TV ethanol tolerance were 1·46, 1·93, and 0·35 min at 60, 70 and 90% respectively. Less than 1 log10 plaque forming units (PFU) reduction was observed for TV at all pH levels except pH 10 where about a 2-log10 PFU reduction was observed. Tulane virus was also tolerant to chlorine disinfection on a solid surface with D-values of 15·82 and 5·42 min at 200 and 1000 ppm respectively. CONCLUSIONS: Tulane virus is likely a suitable surrogate to study HuNoV thermal stability as well as ethanol tolerance below 90%. Tulane virus also is a promising surrogate to study HuNoV pH stability and chlorine tolerance. SIGNIFICANCE AND IMPACT OF THE STUDY: Based on current work, in vitro studies demonstrate that TV is an overall more conservative and suitable surrogate for the study of HuNoV physicochemical properties.

Transfer of Acanthamoeba spp. to fresh produce from water and environmental surfaces.

UNLABELLED: Human noroviruses (HuNoV) are the primary cause of food-borne disease outbreaks in the United States. The most frequent commodities implicated in HuNoV outbreaks are leafy greens where contamination may occur during production and harvesting practices. With respect to the transmission of HuNoV to fresh produce, one hypothesis is that free-living amoebae that are ubiquitous in the environment (soil, sediments and water) can serve as vehicles of contamination through interaction with viruses. Here, we investigated the transfer of Acanthamoeba spp. both alone and associated with murine norovirus (MNV-1)-a surrogate for HuNoV-from water and food contact surfaces to fresh produce to understand the transfer of amoebae and the effect of virus association with amoeba on transferability, if any. In water containing a low concentration of amoebae (3 log10  cell ml(-1) ), 3·85 log10 amoebae transferred to 5 g of leafy greens, and for 5 cherry tomatoes, 3·4 to 3·5 log10 amoebae were transferred. Similarly, for high concentrations of amoeba (5 log10  cell ml(-1) ) in water, 6·14 and 5·81 log10 amoebae were transferred to 5 g leafy greens and five cherry tomatoes respectively. However, the transfer of amoebae from food contact surfaces to fresh produce was very limited. In addition, amoebae association with MNV-1 did not impact transferability. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study provide a better understanding of physical parameters (e.g. surface area and texture of fresh produce, transfer medium-water vs surface) potentially associated with transfer of free-living amoeba to fresh produce as well as the role that contaminated water (irrigation or wash water) may play in the transmission of enteric viruses associated with amoeba.

Diversity and persistence of MRSA and VRE in skilled nursing facilities: environmental screening, whole-genome sequencing and development of a dispersion index.

BACKGROUND: Environmental contamination with meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) in skilled nursing facilities (SNFs) may contribute to patient acquisition. This study assessed diversity and association of MRSA and VRE isolates in an SNF wing, and developed a mathematical index to define the tendency of each strain to persist in rooms and spread horizontally. METHODS: This was a longitudinal study of MRSA and VRE colonization and contamination among successive patient occupancies in a cluster of nine SNF private rooms over 8 months, characterized by microbiological testing and whole-genome isolate typing. The 'dispersion index' of a strain was defined as the number of rooms in which it was found (including if it was found in the patient), divided by the average number of times it was found consecutively in the same room. FINDINGS: MRSA (10 strain types) and VRE (seven types) were recovered from the room or patient in 16.4% and 35.6% of the occupancies, respectively. MRSA showed moderate horizontal spread and several episodes of same-room persistence (three distinct strain types) (overall dispersion index 1.08). VRE showed a high tendency towards horizontal spread/new introductions (overall dispersion index 3.25) and only one confirmed episode of persistence. INTERPRETATION: The emerging picture of high diversity among contaminating strains and high likelihood of room persistence despite terminal cleaning (MRSA) and horizontal spread between rooms (VRE) in this setting calls for improved cleaning practices, heightened contact precautions and, most of all, establishment of individually tailored facility screening programmes to enable informed choices based on local, measurable and actionable epidemiologic parameters.

The mental health impacts of climate change: Findings from a Pacific Island atoll nation.

BACKGROUND: Climate change is anticipated to have profound effects on mental health, particularly among populations that are simultaneously ecologically and economically vulnerable to its impacts. Various pathways through which climate change can impact mental health have been theorised, but the impacts themselves remain understudied. PURPOSE: In this article we applied psychological methods to examine if climate change is affecting individuals' mental health in the Small Island Developing State of Tuvalu, a Pacific Island nation regarded as exceptionally vulnerable to climate change. We determined the presence of psychological distress and associated impairment attributed to two categories of climate change-related stressors in particular: 1) local environmental impacts caused or exacerbated by climate change, and 2) hearing about global climate change and contemplating its future implications. METHODS: The findings draw on data collected in a mixed-method study involving 100 Tuvaluan participants. Data were collected via face-to-face structured interviews that lasted 45 min on average and were subjected to descriptive, correlational, and between-group analyses. RESULTS: The findings revealed participants' experiences of distress in relation to both types of stressor, and demonstrated that a high proportion of participants are experiencing psychological distress at levels that reportedly cause them impairment in one or more areas of daily life. CONCLUSIONS: The findings lend weight to the claim that climate change represents a risk to mental health and obliges decision-makers to consider these risks when conceptualizing climate-related harms or tallying the costs of inaction.

Indwelling urethral versus suprapubic catheters in nursing home residents: determining the safest option for long-term use.

BACKGROUND: The incidence of infectious complications has not been previously compared for two types of common urinary catheters used in the long-term care setting: indwelling urethral catheters and suprapubic catheters. AIM: To compare catheter-associated urinary tract infection (CAUTI) rates and multidrug-resistant organism (MDRO) colonization between nursing home residents with indwelling urethral and suprapubic catheters. METHODS: Participants included 418 nursing home residents with an indwelling device enrolled in a previously published prospective targeted infection prevention study conducted between 2010 and 2013. Resident age, gender, function, comorbidities, and information on infections, antibiotic use, and recent hospitalizations were obtained at study enrolment, day 14, and every 30 days thereafter for up to one year. Microbiological samples were obtained from several anatomic sites at each visit. Cox proportional hazard models were adjusted for facility-level clustering and other covariates. FINDINGS: In all, 208 study participants had an indwelling urinary catheter, contributing 21,700 device-days; 173 (83%) with a urethral catheter, 35 (17%) with a suprapubic catheter. After covariate adjustment, the suprapubic group had a lower incidence of CAUTI (6.6 vs 8.8 per 1000 device-days; P = 0.05), were half as likely to be hospitalized (hazard ratio (HR) = 0.46; P < 0.01) and were 23% less likely to have had antibiotics in the past 30 days (HR = 0.77; P = 0.02). Among residents catheterized ≥90 days, the mean number of MDROs isolated in the suprapubic group was significantly higher than in the urethral group (0.57 vs 0.44; P = 0.01). Ciprofloxacin-resistant Gram-negative bacilli were frequent in both groups. CONCLUSION: Residents with a suprapubic catheter may have fewer CAUTIs, less hospitalization and less antibiotic use, but are more likely colonized with MDROs.

Measuring and mitigating inhibition during quantitative real time PCR analysis of viral nucleic acid extracts from large-volume environmental water samples.

Naturally-occurring inhibitory compounds are a major concern during qPCR and RT-qPCR analysis of environmental samples, particularly large volume water samples. Here, a standardized method for measuring and mitigating sample inhibition in environmental water concentrates is described. Specifically, the method 1) employs a commercially available standard RNA control; 2) defines inhibition by the change in the quantification cycle (C(q)) of the standard RNA control when added to the sample concentrate; and 3) calculates a dilution factor using a mathematical formula applied to the change in C(q) to indicate the specific volume of nuclease-free water necessary to dilute the effect of inhibitors. The standardized inhibition method was applied to 3,193 large-volume water (surface, groundwater, drinking water, agricultural runoff, sewage) concentrates of which 1,074 (34%) were inhibited. Inhibition level was not related to sample volume. Samples collected from the same locations over a one to two year period had widely variable inhibition levels. The proportion of samples that could have been reported as false negatives if inhibition had not been mitigated was between 0.3% and 71%, depending on water source. These findings emphasize the importance of measuring and mitigating inhibition when reporting qPCR results for viral pathogens in environmental waters to minimize the likelihood of reporting false negatives and under-quantifying virus concentration.

A two-year experience teaching computer literacy to first-year medical students using skill-based cohorts.

Because it is widely accepted that providing information online will play a major role in both the teaching and practice of medicine in the near future, a short formal course of instruction in computer skills was proposed for the incoming class of students entering medical school at the State University of New York at Stony Brook. The syllabus was developed on the basis of a set of expected outcomes, which was accepted by the dean of medicine and the curriculum committee for classes beginning in the fall of 1997. Prior to their arrival, students were asked to complete a self-assessment survey designed to elucidate their initial skill base; the returned surveys showed students to have computer skills ranging from complete novice to that of a systems engineer. The classes were taught during the first three weeks of the semester to groups of students separated on the basis of their knowledge of and comfort with computers. Areas covered included computer basics, e-mail management, MEDLINE, and Internet search tools. Each student received seven hours of hands-on training followed by a test. The syllabus and emphasis of the classes were tailored to the initial skill base but the final test was given at the same level to all students. Student participation, test scores, and course evaluations indicated that this noncredit program was successful in achieving an acceptable level of comfort in using a computer for almost all of the student body.

SprE levels are growth phase regulated in a sigma(S)-dependent manner at the level of translation.

SprE regulates sigma(S) levels in response to nutrient availability by promoting ClpXP-mediated degradation. Paradoxically, we observe that SprE is similarly regulated, accumulating preferentially upon starvation. This regulation of SprE levels is sigma(S) dependent, altering SprE synthesis at the level of translation. Thus, we demonstrate that SprE and sigma(S) function within a regulatory feedback loop.

The LysR homolog LrhA promotes RpoS degradation by modulating activity of the response regulator sprE.

Synthesis of the OmpF porin of Escherichia coli is regulated in response to environmental and growth phase signals. In order to identify constituents of the various regulatory pathways involved in modulating ompF transcriptional expression, transposon insertion mutagenesis was performed and mutations that increased ompF'-lacZ activity were identified as previously described. Mutations mapping to a previously identified gene of unknown function, lrhA, were obtained. We found that LrhA, a LysR homolog, functions as a regulatory component in the RpoS-dependent growth phase repression of ompF. In addition to altered growth phase regulation of ompF, these lrhA mutants have pleiotropic stationary-phase defects as a result of decreased RpoS levels. We provide evidence that LrhA promotes degradation of RpoS by functioning within a genetic pathway that includes the response regulator SprE and the ClpXP protease. LrhA functions upstream of the other components in the pathway and appears to modulate the activity of SprE.

From acids to osmZ: multiple factors influence synthesis of the OmpF and OmpC porins in Escherichia coli.

In Escherichia coli, levels of the two major outer membrane porin proteins, OmpF and OmpC, are regulated in response to a variety of environmental parameters, and numerous factors have been shown to influence porin synthesis. EnvZ and OmpR control porin-gene transcription in response to osmolarity, and the antisense RNA, MicF, influences ompF translation. In contrast to these characterized factors, some of the components reported to influence porin expression have only modest effects and/or act indirectly. For others, potential regulatory roles, although intriguing, remain elusive. Here we review many of the components that have been reported to influence porin expression, address the potential regulatory nature of these components, and discuss how they may contribute to a regulatory network controlling porin synthesis.