Rapid reverse phase liquid chromatographic determination of aflatoxin M1 in milk

A rapid, economical, and reliable liquid chromatographic (LC) method is described for determination of aflatoxin M1 in milk. The method includes an improved AOAC extraction procedure, cleanup of the extract on a silica cartridge, and LC quantitation. Alternatively, a rapid column cleanup procedure can be used. Milk artificially spiked with aflatoxin M1 at 0.05, 0.1, and 0.5 ppb was analyzed using both new approaches as well as an AOAC method coupled with LC for quantitation of the toxin. Recovery of aflatoxin M1 by the first approach of the new method ranged between 93.4 and 99.1%, and for the alternative procedure between 92.4 and 96.8%. The AOAC method gave lower recovery (85.6-90.7%) of toxin, but the results from this method had a somewhat smaller standard deviation for replicate analyses than did results of the new method.     

A DOC2 protein identified by mutational profiling is essential for apicomplexan parasite exocytosis

Exocytosis is essential to the lytic cycle of apicomplexan parasites and required for the pathogenesis of toxoplasmosis and malaria. DOC2 proteins recruit the membrane fusion machinery required for exocytosis in a Ca(2+)-dependent fashion. Here, the phenotype of a Toxoplasma gondii conditional mutant impaired in host cell invasion and egress was pinpointed to a defect in secretion of the micronemes, an apicomplexan-specific organelle that contains adhesion proteins. Whole-genome sequencing identified the etiological point mutation in TgDOC2.1. A conditional allele of the orthologous gene engineered into Plasmodium falciparum was also defective in microneme secretion. However, the major effect was on invasion, suggesting that microneme secretion is dispensable for Plasmodium egress.     

Exposure to Bioaerosol from Sewage Systems

We assessed the impacts of a specific conductance gradient attributable to treated coal-mining discharges on the fish communities of a southwestern Pennsylvania stream. Total dissolved solids concentrations were determined from specific conductance values. A total of 10,940 fish representing seven families and 42 species/hybrids were collected from 17 stations over the entire survey. Species richness, density, and the coefficient of community loss (I) showed marked impairment at the two stations directly below the discharges and the downstream recovery was interrupted at one station by untreated discharges from a mine refuse pile. Species richness declined from 28 at the reference site to 7 at the station directly below the treated effluents. This study suggests that the threshold for in-stream conductivity impairment to fish communities in this region is in the range of 3,000–3,500 µS/cm and 2,000–2,300 mg/l of total dissolved solids, respectively.     

Transmission of Campylobacter spp. in a poultry slaughterhouse and genetic characterisation of the isolates by pulsed-field gel electrophoresis

1. Contamination of retail products with Campylobacter spp. during the slaughter of poultry is a well-known problem of product hygiene. Mechanical evisceration often leads to intestinal rupture and discharge of gut contents, which can contain zoonotic and human pathogens. Processes along the slaughter line cause aerosols and airborne droplets, containing bacterial loads. 2. To estimate the possible transmission routes of intestinal Campylobacter, 36 measurements of the bioaerosol (Andersen sampler and SKC BioSampler), 30 cloacal (of three flocks), 10 equipment and 4 sedimentation samples were tested for the presence of Campylobacter species. 3. The results imply that, in addition to contaminated equipment, which was Campylobacter-positive in 80% of cases, aerosols with peak values of 4.0 x 10(4) (test series 1) and 1.4 x 10(4) (test series 2) CFU/m3 also provide a potential vector for horizontal transmission. 4. To explore the genetic similarities of isolates from different origins, 18 isolates recovered from air, 26 cloacal, 8 equipment and 4 sedimentation isolates were analysed by pulsed-field gel electrophoresis (PFGE), using the restriction enzymes Sma I and Sal I. The similarity of cloacal isolates with isolates from equipment, air and sediment, suggest that the contamination is of intestinal origin. 5. There were direct links between Campylobacter-positive flocks and the presence of the same strains in the aerosol of the slaughter hall. Air as a potential source for microbial transmission must be taken into account.