Evaluation of the NIOSH BC-251 personal bioaerosol sampler for sampling viable and culturable pathogenic bacteria

![CDATA[Objective: Evaluation of the NIOSH BC-251 personal bioaerosol sampler for the collection of viable and culturable pathogenic bacteria in liquid. Methods: The NIOSH BC-251 sampler was loaded with 7mL of resuscitation buffer (polyethylene glycol 8000, peptone and Tween 20) in the 15 mL centrifuge tube; 1mL of resuscitation buffer in the 1.5 mL centrifuge tube; and a gelatin filter in the 37 mm filter cassette. The SKC Biosamplers were filled with 20 mL of resuscitation buffer. Duplicate samples were collected over a 4 hour period with both samplers in 4 dairies between June and August 2012. Swab samples were also collected from the hygiene station, disinfectant barrell (center aisle) and the parlor wall directly underneath milking stalls at each dairy. Samples and media were transported on ice. 100uL aliquots of samples and/or sample dilutions were inoculated onto chromogenic agar (E. coli 0157, Salmonella and Rapid L mono) for counting, and presumptive identification of pathogenic bacteria. Suspect colonies were isolated on to Tryptic Soy Agar to obtain pure cultures, gram stained and ribotyped with the DuPont Qualicon Microbial Characterization System. Results: The NIOSH BC-251 samplers had a significant reduction in evaporation losses in comparison to the SKC biosamplers. Viable and culturable bacteria, in particular gram-negative speces, were collected by both samplers and included; Escherichia coli, Stenotrophomonas maltophilia, Citrobacter ferundii, Enterobacter sp. and Pseudomonas sp. E. coli 0157:H7, Salmonella sp. or Listeria monocytogenes where not detected in either the air or swab samples. Conclusions: The NIOSH BC-251 sampler is a portable, durable and discrete bioaerosol sampler which could make an ideal replacement for glass impingers in food production facilities where broken glass can present a significant hazard for food safety. Research is underway to assess any variation in the particle collection efficiency of the BC-251 from the addition of a liquid into the sampling system.]]