Carbapenemase producing Gram negative bacteria: Review of resistance and detection methods.

Gram negative bacilli that are carbapenem resistant have emerged and are spreading worldwide. Infections caused by carbapenem resistant isolates posses a significant threat due to their high morbidity and mortality rates. Carbapenemases production by multi-drug resistant pathogens severely restricts treatment choices for illnesses caused by bacteria that are resistant to both carbapenems and majority of ß-lactam antibiotics. Various phenotypic and genotypic methods for identification can distinguish between different classes of carbapenemase and identify pathogens that are resistant to carbapenems. The establishment of a quick, accurate and reliable test for identifying the clinical strains that produce the carbapenemase enzyme is essential for optimum diagnosis of microbial pathogens and management of the global rise in the prevalence of carbapenemase producing bacterial strains. The aim of this review was to summarize the mechanisms of carbapenem resistance and to provide an overview of different carbapenemase detection methods for carbapenem resistant Gram negative bacilli.

Co-occurrence of Screen Time and Eating Behaviors among Young Children Aged 5 to 9 Years.

BACKGROUND: High screen time, high energy dense food and low fruits and vegetables are important risk factors among children. The study aimed to find out co-occurrence of screen-time and unhealthy eating behavior among young children aged 5 to 9 years in Pokhara Metropolitan. METHODS: A cross-sectional study was conducted among children. Face to face interviews were done with 352 parents of the selected children. The study was conducted from March to October, 2020. High screen time was defined as >2 hours screen viewing each day; low fruit vegetable defined as <3 servings a day; and ≥ one serving a day of energy dense food was categorized as high consumption. RESULTS: Out of total, 33.0% did not met recommendation for single health behavior, 38.9% did not meet for two and 23.9% did not for three health behaviors; and 62.8% had two or more risk behaviors. Of total, 19.6% had low fruit vegetable and high energy dense intake, 17.0% had high screen time and low fruit vegetable, 2.3% high screen time and high energy dense and 23.9% had high screen time, high energy dense and low fruit vegetable. Proportion of co-occurrence of multiple risk behaviors was higher among those whose parents had higher screen time, offered screen devices to them; and the children who had television and television cable at home, and had personal screen device (P<0.05). CONCLUSIONS: About two-third children had multiple risk behaviors; proportion is higher among those who had access to screen devices and higher parental screen time. It may require a combination of efforts to improve healthy behaviors.

Himalayan honey loaded iron oxide nanoparticles: synthesis, characterization and study of antioxidant and antimicrobial activities.

Background: Himalayan honey, a natural product of wild honey bees found in the Himalayan mountains of Nepal, has been used in medicine for many years. The successful development of nanotechnology and beneficial effects of honey would bring a new opportunity to synthesize hybrid nanomaterials for biomedical applications. Thus, the purpose of this study was to load Himalayan honey onto iron oxide nanoparticles (IO-NPs) and study their antioxidant and antimicrobial activities. Methods: Himalayan honey loaded iron oxide nanoparticles (HHLIO-NPs) were synthesized and X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses were performed for characterization. UV-VIS spectra confirmed the loading of honey onto nanoparticles. The antioxidant activity of these nanoparticles was studied against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical system. We also tested antimicrobial activity of HHLIO-NPs using well diffusion method towards both Gram-positive and Gram-negative bacterial strains of Staphylococus aureus & Escherichia coli. Results: From XRD analysis, the average particle size was found to be 33-40 nm. The SEM images show needle shape porous structures of HHLIO-NPs compared to free IO-NPs indicating the surfactant-like behaviour of honey. In DPPH radical system, the scavenging activities of Himalayan honey (HH), free IO-NPs and HHLIO-NPs ranged 7.93-35.99%, 11.02-52.02% and 16.10-80.52% respectively, with corresponding IC50 values of 1.36 mg/mL, 1.09 mg/mL and 0.52 mg/mL. The antimicrobial property of all test samples showed a noteworthy inhibition on both bacterial strains. However, the HH and HHLIO-NPs exhibited strong antibacterial activity against E. coli. Conclusion: This work reveals that the biological activity of HH is enhanced significantly after loading into IO-NPs. Thus, the HHLIO-NPs would be a promising alternative for antioxidant and antimicrobial agents.

Surface-charge effects on the electro-orientation of insulating boron-nitride nanotubes in aqueous suspension.

The alignment of hexagonal boron-nitride nanotubes (BNNTs) in aqueous KCl solutions under spatially uniform electric fields was examined experimentally, using direct optical visualization to probe the orientation dynamics of individual BNNTs for different electric-field frequencies. Different from most previously studied nanowires and nanotubes, BNNTs are wide-bandgap materials which are essentially insulating at room temperature. We analyze the electro-orientation of BNNTs in the general context of polarizable cylindrical particles in liquid suspensions, whose behavior can fall into different regimes, including alignment due to Maxwell-Wagner induced dipoles at high frequencies, and alignment due to fluid motion of the electrical double layer around the particles at lower frequencies. For BNNTs, the variation of the crossover frequencies in the electro-orientation spectra was studied in electrolytes of different conductivity. The effect of BNNT surface charge on electro-orientation was further studied by changing the pH of the aqueous solution. We find that the electric-field alignment of the BNNTs in the low-frequency regime is associated with the charging and motion of the electrical double layer around the particle. However, as BNNTs are non-conducting particles, the reasons for the formation of the electrical double layer are likely to be different than that of conducting particles. We discuss two possible mechanisms for the double-layer formation and alignment of 1D dielectric particles, and make comparison to those for the more commonly studied conducting particles.

Boron Nitride Nanotubes: Recent Advances in Their Synthesis, Functionalization, and Applications.

A comprehensive overview of current research progress on boron nitride nanotubes (BNNTs) is presented in this article. Particularly, recent advancements in controlled synthesis and large-scale production of BNNTs will first be summarized. While recent success in mass production of BNNTs has opened up new opportunities to implement the appealing properties in various applications, concerns about product purity and quality still remain. Secondly, we will summarize the progress in functionalization of BNNTs, which is the necessary step for their applications. Additionally, selected potential applications in structural composites and biomedicine will be highlighted.

A Simple and Universal Technique To Extract One- and Two-Dimensional Nanomaterials from Contaminated Water.

We demonstrate a universal approach to extract one- and two-dimensional nanomaterials from contaminated water, which is based on a microscopic oil-water interface trapping mechanism. Results indicate that carbon nanotubes, graphene, boron nitride nanotubes, boron nitride nanosheets, and zinc oxide nanowires can be successfully extracted from contaminated water at a successful rate of nearly 100%. The effects of surfactants, particle shape, and type of organic extraction fluids are evaluated. The proposed extraction mechanism is also supported by in situ monitoring of the extraction process. We believe that this extraction approach will prove important for the purification of water contaminated by nanoparticles and will support the widespread adoption of nanomaterial applications.

Switching Behaviors of Graphene-Boron Nitride Nanotube Heterojunctions.

High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous, h-BN sheets and BN nanotubes (BNNTs) are wide band gap insulators. Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 10(5) at a turn-on voltage as low as 0.5 V were recorded. Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.

Intestinal parasitic infection among the HIV-infected patients in Nepal.

INTRODUCTION: Intestinal parasitic infection has been a significant problem in HIV patients, worldwide. In this study, we aimed to measure the prevalence and identify the factors associated with intestinal parasitic infection in people infected with HIV and attending National Public Health Laboratory in Kathmandu, Nepal, for CD4 T-cell count. METHODOLOGY: An analytical cross-sectional study in 745 HIV-infected people attending for CD4 T-cell count was conducted. RESULTS: The prevalence of intestinal parasitic infection was 22.4% (95% CI 19.5 to 25.5). In univariate analysis, age, sex, longer time since diagnosis of HIV, CD4 T-cell count of <200/µL, diarrhoea, marital status, and being under tuberculosis (TB) treatment were significantly associated with increased odds of intestinal parasite infection. However, in the logistic regression model, only the CD4 T-cell count of <200/µL (adjusted OR=4.2, 95% CI 2.5 to 7.0), diarrhoea (adjusted OR=2.8, 95% CI 1.8 to 4.3) and being under TB treatment (adjusted OR=2.9, 95% CI 1.8 to 4.6) remained as significant predictors. On stratification, CD4 T-cell count of <200/ µL was independently associated with higher odds of protozoal as well as helminthes infection. The parasites Cryptosporidium and Cyclospora were observed only in participants with CD4 T-cell counts <200/µL. CONCLUSIONS: Both protozoal and helminthic intestinal parasitic infections are common in HIV-infected people seeking care in healthcare facilities. The poor immune status as indicated by low CD4 T-cell count and TB may account for such a high risk of parasitic infection.

Improvement in immunological parameters in patients receiving highly active anti-retroviral therapy in Nepal.

Highly active anti-retroviral therapy (HAART) has been freely available in Nepal since 2004. In the present longitudinal study, we followed two distinct cohorts of human immunodeficiency virus-infected participants, those receiving HAART and those under assessment of eligibility for HAART, during the period 2005-2007 in Kathmandu, Nepal. The median change in CD4+ T-cell count among participants receiving HAART after 12 months of the initiation of therapy was +118 T cells/µl (95% confidence interval [CI], +91 to +145 T cells/µl) and that among participants under assessment of eligibility for HAART was -74 T cells/µl (95% CI, -103 to -44 cells/µl). However, the median CD8+ T-cell count after 12 months remained stable in both the cohorts (P > 0.05). The CD4+/CD8+ T-cell ratio increased from 0.16 to 0.26 after 12 months of therapy (P < 0.001). The multivariate regression model revealed that participants >30 years of age, and injection drug users had significantly lower increases in the CD4+ T-cell count in response to therapy. We observed a high proportion of loss to follow-up after 12 months of therapy; however, the associated factors were unknown. In conclusion, we observed a significant improvement in the CD4+ T-cell count in participants receiving HAART; however, the CD4+/CD8+ T-cell ratio remained <0.5 after 12 months of treatment.

Strongly modified spontaneous emission decay rate of silicon nanocrystals near semicontinuous gold films.

We investigate the spontaneous emission decay rate of Si nanocrystals modified by thin semicontinuous gold films. It has been shown that the mean and standard deviation values of decay rate distribution obtained from the photo-emission decay curve analysis increase due to the deposition of semicontinuous gold films. These values are dependent on gold film thickness and emission wavelength. The observed results are well explained using a point-dipole decay rate model considering the effective dielectric functions of the gold films that exhibit peculiar structures in the localized surface plasmon resonance region.

Co-infection rate of HIV, HBV and Syphilis among HCV seropositive identified blood donors in Kathmandu, Nepal.

BACKGROUND: HIV, HBV, Syphilis and HCV share common modes of transmission. OBJECTIVE: The study was aimed to determine the co-infection rate of HIV, HBV and Syphilis among HCV seropositive identified blood donors. METHODS: The study was conducted on blood samples screened as HCV seropositive at Nepal Red Cross Society, Central Blood Transfusion Service, Kathmandu, Nepal. HCV seropositive samples were further tested for HIV, HBV and Syphilis. RESULTS: Eight co-infections were observed in 139 HCV seropositives with total co-infection rate of 5.75% (95% CI=2.52-11.03). CONCLUSION: Co-infection of HIV, HBV and Syphilis with HCV is prevalent in the healthy looking blood donors of Kathmandu, Nepal.

Factors associated with high prevalence of pulmonary tuberculosis in HIV-infected people visiting for assessment of eligibility for highly active antiretroviral therapy in Kathmandu, Nepal.

BACKGROUND: Tuberculosis is the leading cause of deaths among HIV patients. In this study, we estimated the prevalence of pulmonary tuberculosis (PTB) and identified the factors/co-morbidities associated with active PTB in HIV-infected people visiting the national public health laboratory to assess their eligibility to receive highly active antiretroviral therapy. METHODS: A cross-sectional study was conducted to measure the prevalence of pulmonary tuberculosis. Data on probable risk factors in patients with and without PTB were compared, calculating the odds ratio as a measure of association. Factors showing significant association in univariate analyses were included in a stepwise backward logistic regression model to adjust for confounding. RESULTS: The prevalence of pulmonary tuberculosis was 32.4 % (95% confidence interval (CI) 30.25-34.56). In the univariate analysis, patients with PTB were more likely to be older, married, and have a longer duration since the diagnosis of HIV, diarrhoea, parasitic infection, lower CD4 T-cell counts, and lower CD4/CD8 ratio. However, the backward stepwise logistic regression revealed that only the CD4 T-cell count < 200/µL (AOR 11.69, 95% CI 6.23-21.94), CD4 T-cell count 200-350/µL (AOR 2.52, 95% CI 1.30-4.89), diarrhoea (AOR 2.77, 95% CI 1.78-4.31), parasitic infection (AOR 3.34, 95% CI 2.02-5.50) and 'sex with partner' as probable modes of transmission (AOR 0.44, 95% CI 0.20-0.93) were independently associated with pulmonary tuberculosis. CONCLUSION: A high prevalence of pulmonary tuberculosis was observed. Participants with tuberculosis were significantly more likely to have lower CD4 counts, diarrhoea, and parasitic infections. HIV treatment programmes should consider these factors for better outcomes.

Transfusion-transmissible infections among blood donors in Kathmandu, Nepal.

BACKGROUND: Screening of transfusion-transmissible infections (TTIs) among blood donors can be a cost-effective approach to monitor the prevalence, distribution, and trends of the infections among healthy-looking individuals. The study aimed to determine the seroprevalence of four TTIs, human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis, among blood donors in Kathmandu, Nepal. METHODOLOGY: A total of 21,716 units of blood were tested for the presence of anti-HIV 1/2 IgG/IgM, HBsAg, anti-HCV IgG/IgM, and anti-Treponema pallidum IgG/IgM/IgA using commercial ELISA kits following standard protocols. Statistical analysis was performed using WinPepi Ver 3.8. RESULTS: Seroprevalence of HIV, HBV (HBsAg), HCV and syphilis were observed to be 0.12% (95% CI = 0.08-0.18), 0.47% (95% CI = 0.39-0.57), 0.64% (95% CI = 0.54-0.75) and 0.48% (95% CI = 0.40-0.59) respectively. TTIs were dominant among male blood donors compared to female blood donors. Higher HCV seroprevalence among males compared to females was statistically significant. HIV prevalence was highest among blood donors in the age group 31 to 40 years (P > 0.5). HBV, HCV and syphilis prevalence was highest among blood donors 41 to 50 years age group, 21 to 30 years age group, and 51 to 60 years age group respectively (P < 0.05). HIV and HBV prevalence was relatively higher among first-time donors, whereas HCV and syphilis was relatively higher among the repeated donors (P > 0.05). CONCLUSIONS: It is of utmost importance to continue screening donated blood with highly sensitive and specific tests and to counsel donors who are positive to any of the above infections. It is absolutely necessary to avoid the transmission of infection from repeat donors.

Seroprevalence of HIV and hepatitis C co-infection among blood donors in Kathmandu Valley, Nepal.

We assessed the seroprevalence of human immunodeficiency virus (HIV) in different categories of blood donors and the hepatitis C virus (HCV) co-infection rate. A total of 33,255 blood samples were screened for HIV using a third generation ELISA test at the Central Blood Transfusion Service, Nepal Red Cross Society, Kathmandu from December 2006 to September 2007. The seroprevalence of HIV was 0.19% (95% CI= 0.15-0.25) and co-infection with HCV was found in 10.8% (95% CI= 4.4-20.9). There were no significant differences in HIV seroprevalence among the different categories of age, sex, type of donation and time of donation. The study revealed a relatively lower seroprevalence of HIV among blood donors in Kathmandu Valley than reported earlier but a higher HCV co-infection rate. The similar seroprevalence between first time and repeat donors suggests the need for more improved donor education and counselling.

Trends in hepatitis B and hepatitis C seroprevalence among Nepalese blood donors.

In Nepal, hepatitis B and hepatitis C are considerable health problems. This study aimed to assess the trends of hepatitis B virus (HBV) and hepatitis C virus (HCV) seroprevalence in blood donors over the last 6 years nationwide and in the urbanized setting of Kathmandu Valley. This was a retrospective study conducted among Nepalese blood donors through the years 2001/2002-2006/2007. Serum samples were tested for hepatitis B surface antigen and anti-HCV antibodies using third generation ELISA tests. The donors' information was collected via the donor record register through their respective Blood Transfusion Services. The software, Winpepi ver 3.8 was used for statistical analysis. The overall seroprevalence rates of HBV and HCV in a nationwide analysis were observed to be 0.82 and 0.47%, respectively, and at Central Blood Transfusion Service (CBTS), Kathmandu, the rates were 0.92 and 0.71%, respectively. The seroprevalence of HBV was significantly higher than the seroprevalence of HCV, both nationwide and at CBTS (P < 0.05). An overall significantly decreasing trend was observed in HBV and HCV seroprevalence both nationwide and at CBTS, Kathmandu, over the last 6 years (P < 0.05). Though the overall trend was significantly decreasing, the test for departure from a linear trend also showed a statistically significant result (P < 0.05).

Seroprevalence of human immunodeficiency virus in Nepalese blood donors: A study from three regional blood transfusion services.

BACKGROUND AND OBJECTIVE: The likelihood of human immunodeficiency virus (HIV) infection occurring in recipients of HIV seropositive blood is close to 100%. Transmission during window period is still possible even each unit of blood is tested for anti-HIV 1 and 2 antibodies. The possibility of window period transmission would be minimized if blood is collected from low risk targeted general public. A continuous surveillance data might prove valuable for concerned authorities to assess their service and plan for further improvements in transfusion safety. Our aim was to determine the seroprevalence of HIV in regional blood transfusion services located at three developmental regions of Nepal and compare the results. MATERIALS AND METHODS: A total of 16,557 blood donors were screened for anti-HIV 1 and 2 antibodies in three blood transfusion services viz. 5,351 donors in Morang, 5,211 in Banke, 5,995 in Kaski by using rapid anti HIV 1 and 2 Test. The statistical significance of difference in seroprevalence was tested by Fisher's Exact Test using the statistical software 'Winpepi ver 3.8'. RESULTS: The overall seroprevalence of HIV among blood donors in the regional blood transfusion services was 0.054% (9/16557) and 100% seropositivity was among male donors. The individual seroprevalence in Morang was 0.019%, in Banke was 0.095% and in Kaski was 0.05%. The HIV seroprevalence was not significantly different in regional blood transfusion services of Nepal (Fisher Exact Test, P = 0.2096). CONCLUSION: The seroprevalence in the regional blood transfusion service of Nepal was quite low and the seroprevalence rate was not significantly different.