Woubit Abdela

Nanoengineered Eggshell–Silver Tailored Copolyester Polymer Blend Film with Antimicrobial Properties

In this study, the reinforcement effect of different proportions of eggshell/silver (ES-Ag) nanomaterial on the structural and antimicrobial properties of 70/30 poly(butylene-co-adipate terephthalate)/polylactic acid (PBAT/PLA) immiscible blends was investigated. The ES-Ag was synthesized using a single step ball milling process and characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). These results confirmed the existence of silver nanoparticles (Ag NPs) in the interstitial spaces of the eggshell particles. The thin films in this study were prepared using hot melt extrusion and 3D printing for mechanical and antimicrobial testing, respectively. These films were also characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), XRD, tensile testing, and antimicrobial analysis. It was found that the incorporation of ES-Ag (0.5-2.0% content) compromised the tensile properties of the blend, due to poor interaction between the matrix and the ES-Ag in the ternary systems, but thermal analysis revealed improvement in the onset of degradation temperature and char yield at 500 °C. Though film toughness was better than that of PLA, the strength was lower, yet synergistic to those of PBAT and PLA. In general, the PBAT/PLA/ES-Ag ternary system had properties intermediate to those of the pure polymers. In vitro assessment of the antimicrobial activity of these films conducted on Listeria monocytogenes and Salmonella Enteritidis bacteria revealed that the blend composite films possessed bacteriostatic effects, due to the immobilized ES-Ag nanomaterials in the blend matrix. Atomic absorption spectroscopy (AAS) analysis of water and food samples exposed to the films showed that Ag NPs were not released in distilled water and chicken breast after 72 and 168 h, respectively.

Prevalence and serotypes of Salmonella spp. on chickens sold at retail outlets in Trinidad

Background This cross-sectional study determined the prevalence of Salmonella spp. and their serotypes on dressed chicken sold at retail outlets in Trinidad. The study also investigated the risk factors for contamination of dressed carcasses by Salmonella spp. at cottage poultry processor outlets where chickens are slaughtered and processed for sale. Methods A total of 133 dressed, whole chickens and 87 chicken parts from 44 cottage poultry processors and 36 dressed, whole chickens and 194 chicken parts from 46 supermarket outlets were randomly collected throughout the country. Isolation and identification of Salmonella spp. were performed using standard bacteriological techniques. Serotyping was performed by a regional reference laboratory. Results The prevalence of Salmonella spp. in chicken carcasses sampled from cottage poultry processors and supermarkets was 20.5% and 8.3% respectively (p <0.001). The frequency of isolation of Salmonella spp. at cottage poultry processors was 22.4%, 23.0%, 7.1%, and 10.0% for non-chilled whole chicken, non-chilled chicken parts, chilled whole chicken and chilled chicken parts respectively. Fresh, non-chilled chicken (22.6%) yielded a higher frequency of isolation of Salmonella spp. than chilled chickens (8.3%). For supermarket samples, the frequency of isolation of Salmonella spp. was 19.0%, 8.1%, 0.0% and 7.6% for chilled whole chickens, chill chicken parts, frozen whole chicken and frozen chicken parts respectively. The swab method of sampling yielded a statistically significantly (p = 0.029) higher frequency (3.2%) of Salmonella spp. than the rinse method (1.6%). The predominant serotypes isolated were Kentucky (30.9%) and Javiana (22.7%). Use of chilled water-bath to cool carcasses was the only risk factor significantly (p = 0.044) associated with isolation of Salmonella spp. Conclusion Raw chicken carcasses purchased from cottage poultry processors pose a significantly higher risk of contamination with Salmonella spp. than those sold at supermarkets.

Antimicrobial Resistance of Salmonella Isolates Recovered from Chickens Sold at Retail Outlets in Trinidad

This study determined the frequency of resistance of 135 isolates of Salmonella, including 15 serotypes recovered from chickens purchased from retail outlets (cottage processors and supermarkets) across Trinidad. Resistance to 16 antimicrobial agents was determined by using the disk diffusion method. Resistance among the isolates was related to the type of retail outlet, location of outlets, type of sample, and isolate serotype. Overall, all isolates exhibited resistance to one or more of the 16 antimicrobial agents tested. All isolates were sensitive to cefoxitin and norfloxacin, with the overall frequency of resistance ranging from 1.1% (sulfamethoxazole-trimethoprim) to 100.0% (ceftiofur and doxycycline). The frequency of resistance to tetracycline, ampicillin, ceftriaxone, amoxycillin-clavulanic acid, and chloramphenicol was significantly ( P < 0.05) higher in isolates recovered from cottage processor outlets compared with those from supermarkets. The frequency of resistance to antimicrobial agents was significantly different only to kanamycin ( P = 0.046) and enrofloxacin ( P = 0.000) across seven counties in Trinidad). Regarding sample presentation (whole versus parts), the frequency of resistance was only significantly higher to gentamicin ( P = 0.039) for chicken part isolates from cottage processor and to only tetracycline ( P = 0.034) for isolates from whole carcasses from supermarkets. All the 135 Salmonella isolates exhibited multidrug resistance patterns. The high frequency of resistance to seven antimicrobial agents (erythromycin, streptomycin, ceftiofur, doxycycline, kanamycin, tetracycline, and ampicillin), some used in the poultry industry, coupled with the occurrence of multidrug resistance, may have potential therapeutic implications for broiler farmers in Trinidad.

Nanoparticles for Detection, Diagnostics, and Targeting using Hyperspectral Imaging

Novel and modified nanoparticles containing multiple inherent and specific functionalities make them powerful tools in bioimaging, cancer targeting, cancer therapy, and microbial capture and detection. For example, gold and iron oxide nanoparticles offer potential advantages in the bioimaging of cancer cells due to their respective strong absorption and scattering, and magnetic properties. Several studies in the literature suggest the potency and efficiency of these nanoparticles in therapeutic applications. For example, per Alhalili Z. et al (2016), there was no observed significant decrease (P>0.05) in cell viability when TD47 cells are treated with gold nanoparticles (AuNPs) alone. However, the same cells were significantly killed by the application of AuNPs chemically conjugated to Taxol, suggesting the potential of gold nanoparticles for efficient delivery of Taxol to breast cancer cells. Similarly, Ding R.L. (2017) reported the release of endostatin (ES) in a sustained manner in vitro that showed an excellent inhibitory effect on HUVECs proliferation and migration. The study concluded that ES-NPs significantly improved the anticancer activity of ES by affecting angiogenesis. Despite similar developments in nanomaterial research, much remains to be done in terms of the characterization of the interaction between the cells and the drug loaded nanoparticles. In this study, we report the use of CytoViva Hyperspectral Imaging technology to identify cellular uptake of nanoparticles and to attempt to characterize (if any), the interaction between selected NPs and colon cancer cells.

Simultaneous Detection of Multiple Salmonella Serovars from Milk and Chicken Meat by Real-Time PCR Using Unique Genomic Target Regions

A novel genomic and plasmid target-based PCR platform was developed for the detection of Salmonella serovars Heidelberg, Dublin, Hadar, Kentucky, and Enteritidis. Unique genome loci were obtained through extensive genome mining of protein databases and comparative genomic analysis of these serovars. Assays targeting Salmonella serovars Hadar, Heidelberg, Kentucky, and Dublin had 100% specificity and sensitivity, whereas those for Salmonella Enteritidis had 97% specificity and 88% sensitivity. The limits of detection for Salmonella serovars Heidelberg, Kentucky, Hadar, Enteritidis, and Dublin were 12, 9, 40, 13, and 5,280 CFU, respectively. A sensitivity assay was also performed by using milk artificially inoculated with pooled Salmonella serovars, yielding a detection limit of 1 to10 CFU/25 mL of milk samples after enrichment. The minimum DNA detected using the multiplexed TaqMan assay was 75.8 fg (1.53 × 101 genomic equivalents [GE]) for Salmonella Heidelberg, 140.8 fg (2.8 × 101 GE) for Salmonella Enteritidis, and 3.48 pg (6.96 × 102 GE) for Salmonella Dublin. PCR efficiencies were 89.8% for Salmonella Heidelberg, 94.5% for Salmonella Enteritidis, and 75.5% for Salmonella Dublin. Four types of 30 pasteurized milk samples were tested negative by culture techniques and with a genus-specific Salmonella invA gene PCR assay. Among 30 chicken samples similarly tested, 12 (40%) were positive by both culture and the invA PCR. Testing of these 12 samples with the serovar-specific PCR assay detected single and mixed contamination with Salmonella Kentucky, Salmonella Enteritidis, and Salmonella Heidelberg. Five unique primers were designed and tested by multiplex conventional PCR in conjunction with the use of the multiplex TaqMan assay with three of the primers. The diagnostic assays developed in this study could be used as tools for routine detection of these five Salmonella serovars and for epidemiological investigations of foodborne disease outbreaks.