Chapter outline: Surface Sampling

Proposed topics for “Surface Sampling” chapter                   L. J. Rose, M.J. Arduino, J. Noble-Wang

Proposed as an overview; not a “how to,” but instead a “principles of surface sampling” approach.

Objectives:      1) present general methods, tools and approaches to surface sampling for a variety of purposes, and    2) discuss relevant caveats to be considered before, during and after sampling.

1.     Who, what, where and when of surface sampling : food industry, healthcare, aerospace, biothreat investigation, etc., and current industry standards for surface sampling

2.     Why surface sampling is needed: monitor, quantitate, identify

3.     The How of sampling:

a.     Preparing to sample: Define goal/approach (sampling strategy)

b.     Qualitative sampling: Sensitivity, specificity

c.      Quantitative sampling: Efficiency, level of detection, strategy (number of replicates, field blanks  controls , consistency of technique)

d.     Considerations: Surface Area, roughness, porosity, composite samples, efficiency of device for target organism(s), use of neutralizers, viability of organism on surface

4.     Tools and general steps for sampling; advantages, disadvantages and  limitations of each:

a.     Non porous surfaces: swabs, wipes, sponges, contact plates

b.     Porous surfaces: vacuum socks, filter cassettes, forensic filter devices, wet vacuum

5.     Transport to laboratory: dry spores, vegetative cells, viruses

6.     Elution: shaking, vortexing, sonicating, stomaching

7.     Analysis: Considerations for choosing   

a.     Culture: Competition from other organisms, selective media, broth enrichment, neutralizers, ability of organism to be cultured.

b.     Molecular detection: Inhibition by environmental matrices (humic acid, metals, etc.)

8.     Interpretation of data: limitations