Determination of histological and genotoxic parameters of Nile Tilapia, Oreochromis niloticus exposed to lead (Pb).

This study investigates the hazardous effects of lead on the histological and genotoxic parameters of the fish, Oreochromis niloticus. Present work was conducted in a series of three steps. In first step, acute toxicity, LC50 and lethal lead concentration were measured using Probit analysis method. LC50 value and lethal concentration for O. niloticus was measured as 77.673 mgL-1 and 150.924 mgL-1, respectively. In second step, histological changes were assessed by preparing slides of tissues of the gills, liver and kidney of both control and Pb-stressed O. niloticus and examining the respective tissues under the light microscope. The inferences showed significant histological alterations (p<0.05) in the gills of Pb-exposed fish including necrosis, edema, vascular congestion, shortening and curling and lifting of the epithelium of secondary lamella in gills. The cellular degeneration and dilation of sinusoids in liver and loss of hemopoietic tissue, necrosis and edema in kidney was observed. Histomorphometry of the liver showed a decrease in diameter of the central vein and hepatocyte along with an increase in width of sinusoids. The histomorphometry of kidney showed an increase in the diameter of renal corpuscle, glomerulus, proximal and distal convoluted tubules. The nuclear anomalies were studied in the RBCs of fish. Non-parametric Mann-Whitney U-test was conducted to compare nuclear abnormalities and the frequency of micronuclei among the control and lead-treated fish groups. Results declared an increased micronucleus, notched and de-shaped nuclei frequency, in RBCs of fish exposed to lead as compared to control group.

Evaluation of Sodium Alginate Stabilized Nanoparticles and Antibiotics against Drug Resistant Escherichia coli Isolated from Gut of Houbara Bustard Bird.

Alternative approaches and/or modified approaches to tackle resistance in gut microbes are need of the hour. The current study was planned to find the resistance modulation and toxicity potential of sodium alginate stabilized MgO nanoparticles and antibiotics against Escherichia coli (E. coli) isolated from the gut of Houbara bustard bird (n = 105 fecal samples). The preparations consisted of gel stabilized ampicillin (G+A), gel stabilized MgO and ampicillin (G+M+A), gel stabilized MgO and cefoxitin (G+M+C), gel stabilized tylosin (G+T), gel stabilized MgO and tylosin (G+M+T), and gel stabilized MgO (M+G). The fecal samples showed 53% (56/105) prevalence of E. coli which was found to be significantly (p < 0.05) associated with most of the assumed factors and resistant to multiple drugs. G+M+T showed the lowest (4.883 ± 0.00µg/mL) minimum inhibitory concentration (MIC) followed G+M+C, G+M+A, G+A, M+G, and G+T. Significant reduction (p < 0.05) in MIC with respect to incubation interval found at the 16th hr for G+M+A, G+A, and G+M+C that further remained nonsignificant (p > 0.05) onwards until the 24th hr of incubation. In the case of G+T and M+G, significant reduction in MIC was found at the 20th hr and 24th hr of incubation. Ecotoxicology and histopathology trials on snails showed mild changes in MICs of the preparations. The study thus concluded increasing drug resistance in E. coli of houbara bird while sodium alginate stabilized MgO nanoparticles and antibiotics were effective alternative antibacterial composites with mild toxicity.

Quantitative assessment of faecal shedding of ß-lactam-resistant Escherichia coli and enterococci in dogs.

Quantitative data on faecal shedding of antimicrobial resistant bacteria are crucial to assess the risk of transmission from dogs to other animals as well as humans. In this study we investigated prevalence and concentrations of ß-lactam-resistant Escherichia coli and enterococci in the faeces of 108 dogs presenting at a veterinary hospital in Denmark. The dogs had not been treated with antimicrobials for 4 weeks prior to the study. Total E. coli and enterococci were quantified by counts on MacConkey and Slanetz-Bartley, respectively. Resistant E. coli and enterococci were counted on the same media containing relevant antibiotic concentrations, followed by species identification using MALDI-TOF. Ampicillin- and cefotaxime-resistant E. coli were detected in 40% and 8% of the dogs, respectively, whereas approximately 15% carried ampicillin-resistant enterococci, mainly Enterococcus faecium. In the faeces of the carriers, the proportion of resistant strains in the total bacterial species population was on average 15% for both ampicillin-resistant E. coli (median faecal load 3.2×10(4)cfu/g) and E. faecium (5.8×10(2) cfu/g), and 4.6% for cefotaxime-resistant E. coli (8.6×10(3) cfu/g). Cefotaxime resistance was associated with the presence of blaCTX-M-1 (n=4), blaCMY-2 (n=4) or multiple mutations in the promoter and coding region of chromosomal ampC (n=1). Altogether the results indicate that the risks of zoonotic transmission of ß-lactam-resistant bacteria via human exposure to canine faeces greatly vary amongst individual dogs and are influenced by unidentified factors other than recent antimicrobial use.