Material stiffness variation in mosquito antennae

The antennae of mosquitoes are model systems for acoustic sensation, in that they obey general principles for sound detection, using both active feedback mechanisms and passive structural adaptations. However, the biomechanical aspect of the antennal structure is much less understood than the mechano-electrical transduction. Using confocal laser scanning microscopy, we measured the fluorescent properties of the antennae of two species of mosquito—Toxorhynchites brevipalpis and Anopheles arabiensis—and, noting that fluorescence is correlated with material stiffness, we found that the structure of the antenna is not a simple beam of homogeneous material, but is in fact a rather more complex structure with spatially distributed discrete changes in material properties. These present as bands or rings of different material in each subunit of the antenna, which repeat along its length. While these structures may simply be required for structural robustness of the antennae, we found that in FEM simulation, these banded structures can strongly affect the resonant frequencies of cantilever-beam systems, and therefore taken together our results suggest that modulating the material properties along the length of the antenna could constitute an additional mechanism for resonant tuning in these species.

High Burden of Staphylococcus aureus Among Native American Individuals on the White Mountain Apache Tribal Lands

BACKGROUND

This study was done to determine the burden of invasive Staphylococcus aureus on the White Mountain Apache Tribal lands.

METHODS

Active population and laboratory-based surveillance for invasive S aureus infections was conducted from May 2016 to April 2018. A case was defined as a Native American individual living on or around the White Mountain Apache Tribal lands with S aureus isolated from a normally sterile body site.

RESULTS

Fifty-three cases were identified. Most cases were adults (90.6%) and had ≥1 underlying medical condition (86.8%), the most common of which were diabetes (49.1%) and obesity (41.5%). A total of 26.4% cases were categorized as community acquired. Most infections were methicillin-resistant (75.5%). A total of 7.5% of cases required amputation, and 7.7% of cases died within 30 days of initial culture. The incidence of invasive S aureus was 156.3 per 100 000 persons. The age-adjusted incidence of invasive methicillin-resistant S aureus was 138.2 per 100 000 persons.

CONCLUSIONS

This community has a disproportionately high burden of invasive methicillin-resistant S aureus compared with the general US population. Interventions are urgently needed to reduce the morbidity and mortality associated with these infections.

The neutron electric dipole moment experiment at the Spallation Neutron Source

Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized 3He, and superfluid 4He will be exploited to provide a sensitivity to ∼ 10−28 e · cm. Our cryogenic apparatus will deploy two small (3 L) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our 3He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of “critical component demonstration,” our collaboration transitioned to a “large scale integration” phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings.

453. High Burden of Invasive and Severe Group A Streptococcus Disease Among Native Americans on the White Mountain Apache Tribal Lands

Background

Native Americans are overrepresented in outbreaks of Group A Streptococcus (GAS) in the United States (US). In 2016, several invasive cases of GAS were detected at the Whiteriver Indian Health Service (IHS) Hospital in Arizona that primarily serves the White Mountain Apache (WMA) Tribe. The objective of this study was to determine the burden of invasive and severe GAS disease among Native Americans on the WMA Tribal lands.

Methods

Prospective population and laboratory-based surveillance for invasive and severe GASinfections was conducted for two years from March 2017 through February 2019. A case was defined as a Native American individual living on or around WMA Tribal lands with GAS isolated from a normally sterile body site (invasive) or from a non-sterile site (e.g., wound, throat, ear) requiring hospitalization (severe). Incidence rates were calculated using the IHS User Population as the denominators. Age-standardized incidence rates were calculated using US Census data from 2015 as the reference group.

Results

157 cases were identified (Year 1: 85; Year 2: 72), including 42 (27%) invasive and 115 (73%) severe cases. Most cases were adults (88.5%; median age: 40.5 years) and had ≥1 underlying medical condition (99.4%), including alcoholism (57.1%), hypertension (37.2%), and diabetes (34.0%). 47.8% of cases had a trigger in the past two weeks, including penetrating trauma (31.8%) and blunt force trauma (14.0%). For 72.9% of cases, a co-infection was detected (most commonly Staphylocccus aureus: 96.8%). 4.5% of cases required amputation and 1.9% died within 30 days of initial culture. The incidence of invasive and severe GAS was 460.9 per 100,000 persons (95% confidence interval: 394.3, 538.8), with no significant difference by year. The incidence was highest among adults ≥65 and lowest among children 5–17 years of age. Age-standardized incidence rates of invasive and severe GAS and invasive only GAS are presented in the Figure.

Conclusion

The WMA community has experienced disproportionately high rates of invasive and severe GAS for over two years. Studies to determine the reservoirs for transmission are urgently needed, as are interventions to reduce the morbidity and mortality associated with these infections.

Disclosures

All authors: No reported disclosures.

444. Better Efficiency, Same Accuracy: Point-of-Care PCR for the Detection of Group A streptococcus in Noninvasive Skin Infections

Background

Group A streptococcus (GAS) is a common cause of skin and soft-tissue infections (SSTIs). Current diagnostic techniques are culture-based and time intensive, requiring the prescription of empiric antibiotics before results are available. New detection tools are needed to hasten the diagnosis and appropriate treatment of SSTIs. The Cobas® Liat® System is a point of care (POC), real-time PCR system developed by Roche Molecular Diagnostics and is used in the United States and Europe to detect GAS from throat swabs within 15 minutes. We evaluated the feasibility and performance characteristics of POC for the detection of GAS in non-severe SSTIs.

Methods

Wound swabs collected from patients presenting to the Whiteriver Indian Health Service Hospital with non-severe SSTIs requiring only outpatient treatment were eligible for inclusion. Two swabs were collected: one swab was cultured on sheep’s blood agar, and the other swab was tested using POC. Compared with culture, we determined the sensitivity (SN), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) for POC to detect GAS in wound samples. We performed chart reviews 30-days from eligibility to assess the potential impact of POC systems on antibiotic use and healthcare utilization for SSTIs.

Results

To date, we have tested 100 (25%) of our target 400 samples (enrollment will be complete in August 2019). Of the 100 samples, 50 (50%) tested positive for GAS by POC, all of which were culture positive for GAS, 49 tested negative by POC (2 after a first invalid result), all of which tested culture negative for GAS (table), and 1 had an invalid POC result even after repeat testing (culture positive for MRSA only) and was excluded from further analysis. Among samples with a valid POC result, POC SN was 100%, SP was 100%, PPV was 100%, and NPV was 100%. The most common mono-infections were MRSA (22%), GAS (18%), and CoNS (6%). Among GAS cases, MSSA (32%) and MRSA (18%) co-infection was common.

Conclusion

POC PCR is highly sensitive and specific for the detection of GAS in non-severe SSTIs. To our knowledge, this is the first prospective study to use this technology for wound samples. POC PCR methods have the potential to accelerate identification of SSTI pathogens and improve antibiotic prescribing.

Disclosures

All authors: No reported disclosures.

1835. High Burden of Invasive Staphylococcus aureus Disease Among Native Americans on the White Mountain Apache Tribal Lands

Background

Native Americans in the southwestern United States (US) have a higher risk of many infectious diseases than the general US population. The objective of this study was to determine the burden of invasive Staphylococcus aureus disease among Native Americans on the White Mountain Apache (WMA) Tribal lands.

Methods

Prospective population and laboratory-based surveillance for invasive S. aureus infections was conducted from May 2016 through April 2018. A case was defined as a Native American individual living on or around the WMA Tribal lands with S. aureus isolated from a normally sterile site. Incidence rates were calculated using the Indian Health Service User Population as the denominator. Age-standardized incidence rates were calculated by direct standardization methods using US Census data from 2015 as the reference.

Results

Fifty-three cases were identified (Year 1: 24; Year 2: 29). Most cases were adults (90.6%; median age: 47.4 years) and had ≥1 underlying medical condition (86.8%), of which the most common were obesity (50.0%) and diabetes (50.0%). 26.4% of cases were categorized as community acquired. Most infections were methicillin-resistant (MRSA; 75.5%). 88.7% of cases were hospitalized, 7.5% required amputation, and 7.7% died within 30 days of the initial culture. The overall incidence of invasive S. aureus was 156.3 per 100,000 persons (95% confidence interval [CI]: 119.4, 204.5) with no significant difference in the incidence by year (Year 1: 141.5; Year 2: 171.1; incidence rate ratio: 1.21; 95% CI: 0.70, 2.08). The overall incidence of invasive MRSA was 118.0 per 100,000 persons (95% CI: 86.5, 160.8) with no significant difference by year (Year 1: 106.1; Year 2: 129.8; incidence rate ratio: 1.22; 95% CI: 0.66, 2.28). The incidence of invasive S. aureus and MRSA increased with age and was highest among individuals 50–64 years of age. The overall age-adjusted incidence of invasive MRSA was 138.2 per 100,000 persons (Year 1: 125.2; Year 2: 150.9, for comparison US 2015 general population: 18.8 per 100,000 persons).

Conclusion

The WMA community has one of the highest reported incidence rates globally of invasive MRSA. Interventions are urgently needed in this community to reduce the morbidity and mortality associated with these infections.

Disclosures

All Authors: No reported Disclosures.

555. The Burden of Invasive Staphylococcus Aureus Disease Among Native Americans on the Navajo Nation

Background

Native Americans in the southwestern United States (US) may be at higher risk for invasive infections due to Staphylococcus aureus. The objective of this study was to determine the burden of invasive S. aureus among Native Americans on the Navajo Nation.

Methods

Prospective population and laboratory-based surveillance for invasive S. aureus infections was conducted from May 2016 through April 2018. A case was defined as a Native American individual living on or around the Navajo Nation with S. aureus isolated from a normally sterile body site. Incidence rates were calculated using the Indian Health Service User Population from 2016 and 2017 as the denominators for Years 1 and 2, respectively. Age-standardized incidence rates were calculated using US Census data from 2015 as the reference group.

Results

363 cases were identified (Year 1: 159; Year 2: 204). Most cases were adults (96.9%; median age: 56.0 years) and had ≥1 underlying medical condition (94.5%), of which the most common were diabetes (63.2%), hypertension (39.1%), and obesity (37.2%). 38.0% of cases were categorized as community acquired and 28.7% of infections were methicillin-resistant (MRSA). 83.2% of cases were hospitalized, 10.7% required amputation, and 6.5% died within 30 days of the initial culture. The overall incidence of invasive S. aureus was 74.4 per 100,000 persons (95% confidence interval [CI]: 67.1, 82.4) with a significantly higher incidence in the second year (Year 1: 64.9; Year 2: 84.0; incidence rate ratio: 1.29; 95% CI: 1.05, 1.59). The overall incidence of invasive MRSA was 21.3 per 100,000 persons (95% CI: 17.6, 25.8) with no significant difference by year (Year 1: 21.2; Year 2: 21.4; incidence rate ratio: 1.01; 95% CI: 0.69, 1.48). The incidence of invasive S. aureus and MRSA increased with age and was highest among individuals ≥65 years of age. The overall age-standardized incidence of invasive MRSA was 25.9 per 100,000 persons (Year 1: 26.0; Year 2: 25.7; for comparison US 2015 general population: 18.8 per 100,000 persons).

Conclusion

The Navajo Nation has a higher burden of invasive MRSA than the general US population. Further research is needed to evaluate trends over time and identify prevention strategies and opportunities for intervention.

Disclosures

All authors: No reported disclosures.

Runs of homozygosity and testicular cancer risk

BACKGROUND

Testicular germ cell tumour (TGCT) is highly heritable but > 50% of the genetic risk remains unexplained. Epidemiological observation of greater relative risk to brothers of men with TGCT compared to sons has long alluded to recessively acting TGCT genetic susceptibility factors, but to date none have been reported. Runs of homozygosity (RoH) are a signature indicating underlying recessively acting alleles and have been associated with increased risk of other cancer types.

OBJECTIVE

To examine whether RoH are associated with TGCT risk.

METHODS

We performed a genome-wide RoH analysis using GWAS data from 3206 TGCT cases and 7422 controls uniformly genotyped using the OncoArray platform.

RESULTS

Global measures of homozygosity were not significantly different between cases and controls, and the frequency of individual consensus RoH was not significantly different between cases and controls, after correction for multiple testing. RoH at three regions, 11p13-11p14.3, 5q14.1-5q22.3 and 13q14.11-13q.14.13, were, however, nominally statistically significant at p < 0.01. Intriguingly, RoH200 at 11p13-11p14.3 encompasses Wilms tumour 1 (WT1), a recognized cancer susceptibility gene with roles in sex determination and developmental transcriptional regulation, processes repeatedly implicated in TGCT aetiology.

DISCUSSION AND CONCLUSION

Overall, our data do not support a major role in the risk of TGCT for recessively acting alleles acting through homozygosity, as measured by RoH in outbred populations of cases and controls.

The burden of Staphylococcus aureus among Native Americans on the Navajo Nation

INTRODUCTION

Native Americans in the southwestern United States have a higher risk for many infectious diseases and may be at higher risk for Staphylococcus aureus due to the high prevalence of risk factors for S. aureus. Recent data on invasive S. aureus infections among Native Americans are limited.

METHODS

Active population- and laboratory-based surveillance was conducted in 2016-2017 on the Navajo Nation to document the rate of invasive S. aureus. A case of invasive S.aureus infection was defined as a Native American individual with S. aureus isolated from a normally sterile body site whose reported community of residence was on or around the Navajo Nation.

RESULTS

One hundred and fifty-nine cases of invasive S. aureus from 152 individuals were identified. The median age of cases was 56.3 years and 35% were female. Thirty-five percent of cases had community-acquired infections. Ninety-three percent of cases had underlying medical conditions, including diabetes (60%) and obesity (42%), 28% of cases had a documented prior S. aureus infection, and 33% were infected with methicillin-resistant S. aureus. The annual incidence of invasive S. aureus and of invasive methicillin-resistant S. aureus was 64.9/100,000 persons and 21.2/100,000 persons, respectively.

CONCLUSIONS

This community has a high burden of invasive S. aureus infections. Further research is needed to identify prevention strategies and opportunities for intervention.

The Future Excess Fraction of Cancer Attributable to High Body Mass Index in Australia

Background: High body mass index (BMI > 25 kg/m2) has been found to be associated with an increased risk of many cancers, including cancers of the colon and rectum, liver, and pancreas. Aim: This study aimed to estimate the future burden of cancer resulting from current levels of overweight and obesity in Australia. Methods: The future excess fraction method was used to estimate the future burden of cancer among the proportion of the Australian adult population who were overweight or obese in 2016. Calculations were conducted for 13 cancer types, including cancers of the colon, rectum, kidney, and liver. Results: The cohort of 18.7 million adult Australians in 2016 will develop ∼7.6 million cancers over their lifetime. Of these, ∼402,500 cancers (5.3%) will be attributable to current levels of overweight and obese. The majority of these will be postmenopausal breast cancers (n = 72,300), kidney cancers (n = 59,200), and colon cancers (n = 55,100). More than a quarter of future endometrial cancers (30.3%) and esophageal adenocarcinomas (35.8%) will be attributable to high body mass index. Conclusion: A significant proportion of future cancers will result from current levels of high body mass index. Our estimates are not directly comparable to past estimates of the burden from overweight and obesity because they describe different quantities - future cancers in currently exposed vs current cancers due to past exposures. The results of this study provide us with relevant up-to-date information about how many cancers in Australia could be prevented.

Sex differences in basal hypothalamic anorectic and orexigenic gene expression and the effect of quantitative and qualitative food restriction

Background

Research into energy balance and growth has infrequently considered genetic sex, yet there is sexual dimorphism for growth across the animal kingdom. We test the hypothesis that in the chicken, there is a sex difference in arcuate nucleus neuropeptide gene expression, since previous research indicates hypothalamic AGRP expression is correlated with growth potential and that males grow faster than females. Because growth has been heavily selected in some chicken lines, food restriction is necessary to improve reproductive performance and welfare, but this increases hunger. Dietary dilution has been proposed to ameliorate this undesirable effect. We aimed to distinguish the effects of gut fullness from nutritional feedback on hypothalamic gene expression and its interaction with sex.

Methods

Twelve-week-old male and female fast-growing chickens were either released from restriction and fed ad libitum or a restricted diet plus 15% w/w ispaghula husk, a non-nutritive bulking agent, for 2 days. A control group remained on quantitative restriction. Hypothalamic arcuate nucleus neuropeptides were measured using real-time PCR. To confirm observed sex differences, the experiment was repeated using only ad libitum and restricted fed fast-growing chickens and in a genetically distinct breed of ad libitum fed male and female chickens. Linear mixed models (Genstat 18) were used for statistical analysis with transformation where appropriate.

Results

There were pronounced sex differences: expression of the orexigenic genes AGRP (P < 0.001) and NPY (P < 0.002) was higher in males of the fast-growing strain. In genetically distinct chickens, males had higher AGRP mRNA (P = 0.002) expression than females, suggesting sex difference was not restricted to a fast-growing strain. AGRP (P < 0.001) expression was significantly decreased in ad libitum fed birds but was high and indistinguishable between birds on a quantitative versus qualitative restricted diet. Inversely, gene expression of the anorectic genes POMC and CART was significantly higher in ad libitum fed birds but no consistent sex differences were observed.

Conclusion

Expression of orexigenic peptides in the avian hypothalamus are significantly different between sexes. This could be useful starting point of investigating further if AGRP is an indicator of growth potential. Results also demonstrate that gut fill alone does not reduce orexigenic gene expression.

Electronic supplementary material

The online version of this article (10.1186/s13293-018-0178-6) contains supplementary material, which is available to authorized users.

Changing distribution and abundance of the malaria vector Anopheles merus in Mpumalanga Province, South Africa

Background: The malaria vector Anopheles merus occurs in the Mpumalanga Province of South Africa. As its contribution to malaria transmission in South Africa has yet to be ascertained, an intensification of surveillance is necessary to provide baseline information on this species. The aim of this study was therefore to map An. merus breeding sites in the Ehlanzeni District of Mpumalanga Province and to assess qualitative trends in the distribution and relative abundance of this species over a 9-year period. Methods: The study was carried out during the period 2005-2014 in the four high-risk municipalities of Ehlanzeni District. Fifty-two breeding sites were chosen from all water bodies that produced anopheline mosquitoes. The study data were extracted from historical entomological records that are captured monthly. Results: Of the 15 058 Anopheles mosquitoes collected, 64% were An. merus. The abundance and distribution of An. merus increased throughout the four municipalities in Ehlanzeni District during the study period. Conclusion: The expanded distribution and increased abundance of An. merus in the Ehlanzeni District may contribute significantly to locally acquired malaria in Mpumalanga Province, likely necessitating the incorporation of additional vector control methods specifically directed against populations of this species.

Case management of malaria in Swaziland, 2011-2015: on track for elimination?

Objective: To assess adherence to malaria diagnosis and treatment guidelines (2010 and 2014) in all health care facilities in Swaziland between 2011 and 2015. Methods: This was a cross-sectional descriptive study involving all health care facilities that diagnosed and managed malaria cases in Swaziland. Patients' age, sex, diagnosis method and type of treatment were analysed. Results: Of 1981 records for severe and uncomplicated malaria analysed, 56% of cases were uncomplicated and 14% had severe malaria. The type of malaria was not recorded for 30% of cases. Approximately 71% of cases were confirmed by rapid diagnostic tests (RDT) alone, 3% by microscopy alone and 26% by both RDT and microscopy. Of the uncomplicated cases, 93% were treated with artemether-lumefantrine (AL) alone, 5% with quinine alone and 2% with AL and quinine. Amongst the severe cases, 11% were treated with AL alone, 44% with quinine alone and 45% with AL and quinine. For severe malaria, clinics and health centres prescribed AL alone more often than hospitals (respectively 13%, 12% and 4%, P = 0.03). Conclusion: RDTs and/or microscopy results are used at all facilities to inform treatment. Poor recording of malaria type causes difficulties in assessing the prescription of antimalarial drugs.

Muddy puddles - the microbiology of puddles located outside tertiary university teaching hospitals

In the British Isles, the frequency of rain results in the formation of puddles on footpaths and roads in/around hospitals. No data are available demonstrating the microbiological composition of such puddles and therefore a study was undertaken to examine the microbiology of puddles in the grounds of two tertiary university-teaching hospitals (18 sites) and compared with control puddles from non-hospital rural environments (eight sites), estimating (i) total viable count; (ii) identification of organisms in puddles; (iii) enumeration of Escherichia coli: (iv) detection of Extended Spectrum β-Lactamase producing organisms and (v) direct antimicrobial susceptibility testing. A mean count of 2·3 × 10³  CFU per ml and 1·0 × 10⁹  CFU per ml was obtained for hospital and non-hospital puddles respectively. Isolates (n = 77; 54 hospital and 23 non-hospital) were isolated comprising of 23 species among 17 genera (hospital sites), where the majority (10/16; 62·5%) of genera identified were Gram-negative approximately, a fifth (20·6%) were shared by hospital and non-hospital rural samples. Escherichia coli was detected in half of the hospital puddles and under-half (37·5%) of the rural puddles extended spectrum β-lactamase organisms were not detected in any samples examined. Rainwater puddles from the hospital and non-hospital environments contain a diverse range of bacteria, which are capable of causing infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated the presence of a wide diversity of bacterial taxa associated with rainwater puddles around hospitals, many of which are capable of causing human disease. Of clinical significance is the presence of Pseudomonas aeruginosa isolated from a hospital puddle, particularly for patients with cystic fibrosis. The presence of potentially disease-causing bacteria in puddles in and around hospitals identifies a new potential environmental reservoir of bacteria. Furthermore work is now needed to define their potential of entering or exiting hospital wards by contaminated footwear.