Submissions of powder and nonpowder environmental samples and human blood or tissue specimens submitted from October 8 through December 31, 2001, were reviewed. Before samples were accepted by IDPH Division of Laboratories, incidents involving environmental samples had to be reviewed by Federal Bureau of Investigations (FBI) agents who determined if a potential bioterrorism threat was credible. The IDPH laboratories in Chicago and Springfield processed all samples submitted through law enforcement authorities in this manner. The Chicago laboratory received samples primarily from northern Illinois (north of Interstate 80), while the Springfield laboratory received samples from central and southern Illinois. The Chicago laboratory followed all required guidelines for a biosafety level 3 laboratory.
The laboratory methods for identifying Bacillus species in environmental samples have been reported elsewhere. Laboratory methods included Gram stain and culture of suspicious colonies grown on blood agar plates, and beta-lactamase, motility, and gamma-phage lysis testing. A malachite green stain for spores was performed on all powder specimens during the initial 2 weeks at the Chicago laboratory and on selected specimens thereafter; an M'Fadyean stain was used at the Springfield laboratory. Polymerase chain reaction (PCR) was performed on those samples requiring the most rapid turnaround time (e.g., specimens submitted by a U.S. Postal Service facility that had been closed pending results). Human samples arrived from hospital laboratories in the form of a tryptic soy agar slant and were plated to blood agar plates upon arrival. Gamma-phage lysis, PCR, or both were performed as needed. The Chicago and Springfield laboratories' processed their first samples on October 8 and October 9, respectively.
Because no data were available regarding what to expect from processing bioterrorism threat-related samples from the environment, Bacillus organisms from most environmental and human samples were speciated, even if negative for B. anthracis.
A total of 1,496 environmental specimens were processed: 1,193 (79.7%) in Chicago and 303 (20.3%) in Springfield. An additional 40 human specimens were processed, 28 (70%) in Chicago and 12 (30%) in Springfield. Chicago sample submissions rose steadily after the first week of October and peaked during the week of October 29 through November 4, with the largest number of submissions processed on November 7 (range 0-64 submissions per day) (Figure). An additional 17 submissions for which the date of submission was not clearly documented, and may have preceded October 8, also were processed. Powdery substances constituted 42.0% of submissions to the Chicago laboratory versus 33.7% of submissions to the Springfield laboratory. Nonpowdery substances (e.g., environmental swab samples, letters, envelopes, packages, and other materials) constituted 58.0% of submissions to the Chicago laboratory versus 66.3% of submissions to the Springfield laboratory. Eight additional environmental samples that did not go through the FBI were received by the Chicago laboratory from hospitals.
Number of environmental specimens submitted to the Illinois Department of Public Health Division of Laboratories.
Among both the powders and nonpowders processed at the Chicago laboratory, the most frequently isolated organisms were Bacillus cereus (19.2% and 8%, respectively) and nonhemolytic staphylococci (23.9% and 22.8%, respectively) ( Table 1 ). Among the eight hospital samples not submitted through the FBI, B. megaterium (four), B. thuringiensis (one), and nonanthracis Bacillus species (three) were identified. Twenty specimens (8 in Chicago and 12 in Springfield) were processed by using PCR. All of these results were negative for B. anthracis.
A review of the source and circumstances related to 57 nonhuman samples submitted to the Chicago laboratory on November 7, 2001 (the date with the highest number of submissions), indicated that most of the items were mail items (e.g., 18 letters or envelopes, 12 unspecified mail items, and 7 packages), but powders (7 submissions) and unspecified "suspicious substance" (13 items) also were identified. Such items came from at least six counties and involved 13 local police departments, the Illinois State Police, two fire departments, and the FBI. In addition to submissions from private citizens, submissions came from two universities, a post office, a private business, and a consulate. A high level of anxiety among the public was likely responsible for the otherwise unsuspicious items submitted, including dairy creamer, powder from donuts, a backpack, a telephone, a frozen dinner, a computer keyboard, and a letter from a married man's lover that was intercepted by his wife and submitted unopened as a suspicious mail item.
Twenty-eight human specimens were submitted to the Chicago state laboratory for evaluation after preliminary testing at an initial laboratory (usually a hospital) could not rule out B. anthracis ( Table 2 ). These included 15 blood cultures. For 12 specimens, the species were not identified, although test results demonstrated they were not any of 16 Bacillus species. An additional 12 specimens submitted to the Springfield laboratory were negative for B. anthracis.
Emerging Infectious Diseases. 2003;9(4) © 2003 Centers for Disease Control and Prevention (CDC)
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