Dissipation and degradation of 14 C-p,p'-DDT (Faisalabad and Peshawar locations) and 14 C-p,p'-DDE (Faisalabad location) were studied for one year in soils under field conditions. Both DDT and DDE dissipated more rapidly under the Pakistani subtropical climate than reported for temperate regions.More binding to soil of 14 C-DDT was observed at Peshawar than that at Faisalabad. Overall halflives were 144 and 313 days in Faisalabad and Peshawar respectively. The main degradation products of p,p'-DDT extracted from soils at the two locations were p,p'-DDE and p,p'-DDD. 14 C-DDE showed an overall halflife of 191 days under Faisalabad field conditions.Since the degradation of both DDT and DDE was not substantial, it is maintained that dissipation of both chemicals was largely due to volatilization/codistillation. About 68-92% of bound 14 C-residues from soils previously treated with 14 C-DDT were released by sulphuric acid treatment. Fresh soil inoculum also released up to 77% after three months.

No abstract

Antibiotic-resistant bacteria causing foodborne serious illnesses can be found in contaminated food. Therefore, this study aimed to identify the pathogens, genes, and antimicrobial residues present in raw milk and meat. We collected 40 raw milk and 40 beef samples using the aseptic method from various parts of the Faisalabad metropolis, Pakistan. The samples were cultured on blood, MacConkey, and UTI chrome agar. The VITEK 2 compact system was used for microbial identification and determination of minimum inhibitory concentrations. Antimicrobial resistance genes for extended-spectrum β-lactamases, methicillin resistance in Staphylococcus aureus, and carbapenem resistance were identified using molecular techniques. ELISA was used to determine the tetracycline residue level in each sample. The beef samples showed polymicrobial contamination with 64 bacterial isolates, with Escherichia coli (29; 45.3%) and Klebsiella pneumoniae (11; 17.1%) predominating. The milk samples showed polymicrobial contamination with 73 bacterial isolates, with E. coli (22; 30%), K. pneumoniae (12; 16.4%), and S. aureus (10; 13.6%) forming the majority. Twenty-eight (43.7%) isolates from beef harbored tet genes, nineteen (29.6%) blaCTX-M, and fourteen (21.8%) blaNDM-1, and twenty-six (35.6%) isolates from milk harbored tet genes, nineteen (26%) blaTEM and blaCTX-M, and three (4%) blaNDM-1. Twenty-two (55%) each of the beef and milk samples exceeded the maximum residue limit for tetracycline. Polymicrobial contamination by bacteria possessing blaCTX-M, blaTEM, blaNDM-1, blaOXA, mecA, and tet genes was identified in food samples. The high tetracycline residue levels pose a serious health risk to consumers.

No abstract

This study was undertaken to develop and validate direct competitive ELISA for the determination of chloramphenicol residues in bovine milk. Antisera and an enzyme-tracer for chloramphenicol were prepared and used to develop an ELISA with inhibition concentrations, IC and IC, of 0.09 and 0.44 ng mL, respectively. Milk samples were spiked with standards equivalent to 0, 0.2, 0.3, 0.5, 1.0 & 1.5 ng mL and extracted in methanol. The mean recoveries were found to be 73-100% with coefficient of variance 7-11%. The decision limit (CCα) and detection capability (CCβ) were calculated as 0.10 and 0.12 ng mL, respectively. The results were found comparable with the commercial ELISA, having recoveries of 87 to 100%, CCα 0.09 ng mL and CCβ 0.12 ng mL. As per Commission Decision 2002/657/EC, in-house ELISA was further validated by using LC-MS/MS. Mass spectral acquisition was done by using electrospray ionization in the negative ion mode applying single reaction monitoring of the diagnostic transition reaction for CAP (m/z 152, 194 and 257). The calibration curve showed good linearity in concentrations from 0.025 to 1.6 ng mL with correction coefficient 0.9902. The mean recoveries were found to be 88 to 100%. The CCα was calculated as 0.057 ng mL and CCβ 0.10 ng mL. Since CCα and CCβ are less than half of the MRPL (0.15 ng mL), the test was found suitable for screening and quantification of CAP residues in bovine milk samples. Results of surveillance studies indicated that out of 31 analyzed milk samples, 12.9% samples were found with CAP residues but only 3.2% samples were declared positive with maximum concentration 0.31 ng mL, slightly above the MRPL.