title: Evaluation of modified moore swabs and continuous flow centrifugation for concentration of Salmonella and Escherichia coli O157:H7 from large volumes of water.
abstract: Modified Moore swabs (MMS; consisting of a polyvinyl chloride cartridge filled with gauze) capture microorganisms within the packed gauze as water flows through the cartridge, while continuous flow centrifugation (CFC) uses centrifugation to sediment the microorganisms while water continuously  flows in the system. This study evaluated and compared the efficacy of MMS and CFC for concentration and subsequent detection of Escherichia coli O157:H7 and Salmonella from large volumes of water (10 liters). Water samples were spiked at levels of 10(1), 10(2),  10(3), and 10(4) CFU/100 ml with three-strain cocktails of either E. coli O157:H7 or Salmonella serovars, which had been previously transformed with a plasmid to express resistance to ampicillin as well as green, red, or cyan fluorescent proteins. Plating was  performed before and after concentration on tryptic soy agar supplemented with ampicillin in order to quantitate the concentration efficiencies of each method. The two lowest spiking levels were also enriched in low volumes of tryptic soy broth supplemented with ampicillin followed by testing  via lateral flow devices. Significant (P < 0.05) concentrations of initial levels of E. coli O157:H7 in the range of 0.7 to 1.0 and 1.2 to 1.4 log were achieved within approximately 35 min of processing time via MMS and CFC, respectively. Similarly, significant (P <  0.05) concentrations were also achieved for Salmonella with 0.9 to 1.2 and 1.2 to 1.4 log concentration for MMS and CFC, respectively. There were no statistical differences (P > 0.05) between the two concentration methods in their ability to concentrate either of the two target  bacteria. Significantly (P > 0.05) more spiked samples were detected by lateral flow devices following concentration and enrichment than for nonconcentrated, enriched samples. It is concluded that both MMS and CFC have potential to be used to enhance the sensitivity of downstream  bacterial detection methods used to test irrigation water for the presence of foodborne pathogens.
authors: Center for Meat Safety and Quality, Food Safety Cluster, Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523, USA. Bledar.Bisha@colostate.edu
authors: Bledar
authors: B
authors: Bisha
authors: Alma
authors: A
authors: Perez-Mendez
authors: Michelle D
authors: MD
authors: Danyluk
authors: Lawrence D
authors: LD
authors: Goodridge
mesh_terms: D002498:Centrifugation / Q000379:methods*; D015169:Colony Count, Microbial / Q000379:methods*; D003257:Consumer Product Safety; D003470:Culture Media / Q000737:chemistry; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005516:Food Microbiology; D006801:Humans; D012475:Salmonella / Q000302:isolation & purification*; D013997:Time Factors; D014871:Water Microbiology
chemical_list: D003470:Culture Media