Concentration and Purity DNA Spectrophotometer: Sodium Monofluorophosphate forensic impended effect

Molecular detection and antibiogram of Shiga toxin-producing Escherichia coli (STEC) from raw milk in and around Bahir Dar town dairy farms, Ethiopia

Illnesses associated with consuming infected milk and milk products are a widespread problem in low and middle-income countries. Shiga toxin-producing Escherichia coli (STEC) is a bacterium commonly found in raw milk and causes foodborne diseases ranging from mild diarrhea to severe hemorrhagic colitis and hemolytic uremic syndrome. This study aimed to investigate the virulence gene and antimicrobial resistance profiles of Shiga toxin-producing E. coli strains isolated from raw milk in dairy farms in and around Bahir Dar town. Raw milk samples (n = 128) collected from December 2021 to July 2022 were cultured, and E. coli strains were isolated using standard methods. Shiga toxin-producing E. coli strains were identified genotypically by the presence of the virulence markers using a single-plex polymerase chain reaction. The antibiotic susceptibility testing of Shiga toxin-producing E. coli isolates was done by the agar disk diffusion method. In total, 32 E. coli isolates were recovered from milk samples from lactating animals. PCR screening of these isolates resulted in 19 (59.3%) positives for Shiga toxin-producing E. coli. The stx2 gene was detected in 53% of cases, followed by stx1 (31%) and eae (16%. The STEC isolates were highly sensitive to ciprofloxacin (94.7%) and kanamycin (89.5%), while exhibiting significant resistance to amoxicillin (89.5%) and streptomycin (73.7%). The present study points out the occurrence of virulent and antibiotic-resistant Shiga toxin-producing E. coli strains in raw milk that could pose a potential risk to public health. Further analysis by whole genome sequencing is necessary for an in-depth assessment and understanding of their virulence and resistance factors. Moreover, large-scale studies are needed to identify the prevalence and potential risk factors and to prevent the spread of antibiotic-resistant STEC strains in the milk production chain.

Comparison of DNA Extraction and Amplification Techniques for Use with Engorged Hard-Bodied Ticks

Tick-borne infections are a serious threat to humans, livestock, and companion animals in many parts of the world, often leading to high morbidity and mortality rates, along with decreased production values and/or costly treatments. The prevalence of the microbes responsible for these infections is typically assessed by the molecular identification of pathogens within the tick vectors. Ticks sampled from animals are often engorged with animal blood, presenting difficulties in the amplification of nucleic acids due to the inhibitory effects of mammalian blood on the enzymes used in polymerase chain reactions (PCRs). This study tested two tick preparation methods, three methods of DNA extraction, and four commercially available DNA polymerases to determine the most reliable method of extracting and amplifying DNA from engorged ticks. Our study found that the phenol–chloroform extraction method yielded the highest concentration of DNA, yet DNA extracted by this method was amplified the least successfully. Thermo Scientific’s Phusion Plus PCR Master Mix was the best at amplifying the tick 16s rRNA gene, regardless of extraction method. Finally, our study identified that using the Qiagen DNeasy Blood & Tissues kit for DNA extraction coupled with either Phusion Plus PCR Master Mix or GoTaq DNA polymerase Master Mix is the best combination for the optimized amplification of DNA extracted from engorged ticks.