Polyester-rayon blend wipes were evaluated for efficiency of extraction and recovery of powdered Bacillus atrophaeus spores from stainless steel and painted wallboard surfaces. Method limits of detection were also estimated for both surfaces. The observed mean efficiency of polyester-rayon blend wipe recovery from stainless steel was 0.35 with a standard deviation of ؎0.12, and for painted wallboard it was 0.29 with a standard deviation of ؎0. It is critical from a public health perspective that the information obtained is accurate and reproducible. The consequences of an inappropriate public health response founded on information garnered by an ineffective sample collection method or procedure has the potential for undesired social and economic impact. Well-developed and validated procedures for the collection and analysis of biological environmental samples are required to provide the necessary level of confidence in agent characterization information provided.Researchers and investigators are aware that the Centers for Disease Control and Prevention (CDC)-recommended procedures for the collection of B. anthracis spores by swab, wipe, and vacuum filtration collection methods (6) underestimate the number of spores on surfaces, and attempts are being made to address the knowledge gap (4,5,18,19). Additionally, a number of studies have been conducted to determine the efficiency of the swab sample collection method (1,2,3,7,8,10,17,18), but limited studies have been conducted to examine the efficiency of the wipe spore collection method (10, 13). A recent study conducted by Sanderson et al. (19) that compared B. anthracis surface sampling results obtained by swab, wipe, and vacuum filtration methods suggests that the wipe collection method outperforms the swab method, but no independent recovery efficiency was established for the wipe method.The objective of this study was to empirically evaluate the wipe surface sample collection method for recovery efficiency with a polyester-rayon blend wipe material and estimate limits of detection for selected nonporous surfaces seeded with dry deposited Bacillus atrophaeus spores. Additionally, a sonication extraction method was evaluated for effectiveness in removing viable spores from the selected wipe collection material. MATERIALS AND METHODSSpore matrix. The material used as the test agent for this study was a powdered matrix containing B. atrophaeus spores (ATCC 9372; formerly Bacillus subtilis var. niger and subsequently "Bacillus globigii") (12) and silicon dioxide particles obtained from the U.S. Army Dugway Proving Ground Life Science Division. The spore material was prepared by cultivating B. atrophaeus in tryptic soy broth (Difco, Detroit, MI) containing 3 mg/liter MnSO 4 (Fisher Scientific, Pittsburgh, PA). After 80 to 90% sporulation, the spore suspension was centrifuged to obtain a spore suspension containing approximately 20% solids. Dry spore material was then prepared from the unwashed spore suspension with a laboratory spray dryer. The spore material was...

Vacuum filter socks were evaluated for recovery efficiency of powdered Bacillus atrophaeus spores from two non-porous surfaces, stainless steel and painted wallboard and two porous surfaces, carpet and bare concrete. Two surface coupons were positioned side-by-side and seeded with aerosolized Bacillus atrophaeus spores. One of the surfaces, a stainless steel reference coupon, was sized to fit into a sample vial for direct spore removal, while the other surface, a sample surface coupon, was sized for a vacuum collection application. Deposited spore material was directly removed from the reference coupon surface and cultured for enumeration of colony forming units (CFU), while deposited spore material was collected from the sample coupon using the vacuum filter sock method, extracted by sonication and cultured for enumeration. Recovery efficiency, which is a measure of overall transfer effectiveness from the surface to culture, was calculated as the number of CFU enumerated from the filter sock sample per unit area relative to the number of CFU enumerated from the co-located reference coupon per unit area. The observed mean filter sock recovery efficiency from stainless steel was 0.29 (SD = 0.14, n = 36), from painted wallboard was 0.25 (SD = 0.15, n = 36), from carpet was 0.28 (SD = 0.13, n = 40) and from bare concrete was 0.19 (SD = 0.14, n = 44). Vacuum filter sock recovery quantitative limits of detection were estimated at 105 CFU m(-2) from stainless steel and carpet, 120 CFU m(-2) from painted wallboard and 160 CFU m(-2) from bare concrete. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling for biological agents such as Bacillus anthracis.

Groups of male B6C3F1 mice (N = 12) were exposed to ambient air or to gaseous 1,3-butadiene (BD) at 6.25, 62.5, and 625 ppm for 10 exposure days (6 hr + T90/day). Exposure to BD induced in bone marrow: 1) a significant increase in the frequency of chromosomal aberrations (CA); 2) a significant elevation in the frequency of sister chromatid exchanges (SCE); 3) a significant lengthening of the average generation time (AGT); 4) a significant depression in the mitotic index (MI); and, as measured in the peripheral blood, 5) a significant increase in the proportion of circulating polychromatic erythrocytes (%PCE), and 6) a significant increase in the level of micronucleated PCE (MN-PCE) and micronucleated normochromatic erythrocytes (MN-NCE). The most sensitive indicator of genotoxic damage was the frequency of SCE (significant at 6.25 ppm), followed by MN-PCE levels (significant at 62.5 ppm), and then by CA and MN-NCE frequencies (significant at 625 ppm). The most sensitive measure of cytotoxic damage was AGT (significant at 62.5 ppm), followed by %PCE (significant at 625 ppm), and then by MI (significant by trend test only). Because each cytogenetic endpoint was evaluated in every animal, a correlation analysis was conducted to evaluate the degree of concordance among the various indicators of genotoxic and cytotoxic damage. The extent of concordance ranged from a very good correlation between the induction of MN-PCE and the induction of SCE (correlation coefficient r = 0.9562) to the lack of a significant correlation between the depression in the MI and any other endpoint (r less than 0.37).

Aim:  To evaluate US Centers for Disease Control and Prevention recommended swab surface sample collection method for recovery efficiency and limit of detection for powdered Bacillus spores from nonporous surfaces. Methods and Results:  Stainless steel and painted wallboard surface coupons were seeded with dry aerosolized Bacillus atrophaeus spores and surface concentrations determined. The observed mean rayon swab recovery efficiency from stainless steel was 0·41 with a standard deviation (SD) of ±0·17 and for painted wallboard was 0·41 with an SD of ±0·23. Evaluation of a sonication extraction method for the rayon swabs produced a mean extraction efficiency of 0·76 with an SD of ±0·12. Swab recovery quantitative limits of detection were estimated at 25 colony forming units (CFU) per sample area for both stainless steel and painted wallboard. Conclusions:  The swab sample collection method may be appropriate for small area sampling (10 –25 cm2) with a high agent concentration, but has limited value for large surface areas with a low agent concentration. The results of this study provide information necessary for the interpretation of swab environmental sample collection data, that is, positive swab samples are indicative of high surface concentrations and may imply a potential for exposure, whereas negative swab samples do not assure that organisms are absent from the surfaces sampled and may not assure the absence of the potential for exposure. Significance and Impact of the Study:  It is critical from a public health perspective that the information obtained is accurate and reproducible. The consequence of an inappropriate public health response founded on information gathered using an ineffective or unreliable sample collection method has the potential for undesired social and economic impact.

Recovery of spores from environmental surfaces varies due to sampling and analysis methods, spore size and characteristics, surface materials, and environmental conditions. Tests were performed to evaluate a new, validated sponge wipe method using Bacillus atrophaeus spores. Testing evaluated the effects of spore concentration and surface material on recovery efficiency (RE), false-negative rate (FNR), limit of detection (LOD), and their uncertainties. Ceramic tile and stainless steel had the highest mean RE values (48.9 and 48.1%, respectively). Faux leather, vinyl tile, and painted wood had mean RE values of 30.3, 25.6, and 25.5, respectively, while plastic had the lowest mean RE (9.8%). Results show roughly linear dependences of RE and FNR on surface roughness, with smoother surfaces resulting in higher mean REs and lower FNRs. REs were not influenced by the low spore concentrations tested ( -an integrated network of state and local public health, federal, military, and international laboratories that can respond to bioterrorism, chemical terrorism, and other public health emergencies. However, results from surface samples were inconsistent. In some cases, contamination at a given location within a facility was not detected with initial samples, and subsequent samples were required to detect the contamination (19). A Government Accountability Office (GAO) investigation following the 2001 anthrax incident concluded that validated sampling methods and statistical sampling designs were needed to provide confidence that there is no contamination when all sample results are negative (17, 18). This conclusion strongly reinforces the need for validated sampling methods to effectively respond to biothreats and ensure public safety.Following the 2001 anthrax incident, several research teams developed and investigated (in laboratory studies) the performance of sampling methods using swab, wipe, and vacuum collection devices for Bacillus anthracis or surrogate contaminants on different surfaces (1,2,3,4,5,6,7,13,14,15,16,22,23,25,28,34,38,40,44,45). In addition, the CDC has conducted formal validation studies on two methods for sampling nonporous surfaces: macrofoam swabs (23) and cellulose sponge wipes (39).A review of the cited laboratory studies identified numerous gaps in the data on method performance (30). For example, none of the studies quantified the false-negative rate (FNR) for the sampling and analysis methods investigated. The term "false negative" refers to a failure to detect contamination from a sample collected at a contaminated location. A false negative can occur because of inefficiencies (i.e., biases) and uncertainties (i.e., imprecision) at any step of the sampling and analysis process (sample collection, storage/transportation, processing/extraction, and analytical). False negatives can occur during preliminary screening or characterization sampling at low contamination levels and during clearance sampling following the decontamination process. A better understanding of FNRs and how they are infl...