Goat Placenta on an Open Bench
At a veterinary teaching hospital's BSL-2 microbiology laboratory, 16 students in a clinical rotations course process a placenta and fetal stomach contents from a goat farm experiencing an abortion storm. The instructor sets up a culture exercise: students open the plates on an open bench, subculture, and, as is customary in the course, smell the plates to describe odor. The laboratory's standard operating procedure classifies livestock clinical specimens as BSL-2 and requires no risk assessment for routine cultures. Five days later, the referring veterinarian emails that Coxiella burnetii PCR is positive on the placental tissue and that three farm workers have confirmed Q fever. The plates are still on the bench and in a 37°C incubator; one student is 12 weeks pregnant and another takes methotrexate. The instructor asks whether to discard the plates, notify anyone, and how to handle the two students.
1. List your immediate actions in the first two hours, in priority order, and justify each. Address the plates, the people, and the documentation.
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- Stop work and secure the room. Do not open, sniff, vortex, or discard the plates. Place them in a sealed secondary container; if they must move, use a closed carrier. Post the laboratory. 2. Notify the biosafety officer, laboratory director, and occupational health immediately; do not wait for a confirmatory culture. Coxiella burnetii is highly infectious by aerosol, and placenta is a high-load tissue. 3. Build an exposure list: all 16 students, the instructor, and anyone who entered the bench area, with times, activities (opening plates, sniffing), duration, and PPE. 4. Refer the pregnant student and the immunosuppressed student to occupational health the same day; pregnancy and immunosuppression increase the risk of severe Q fever. 5. Report to public health as required; Q fever is reportable in many jurisdictions, the farm already has human cases, and the health department needs the laboratory exposure information. 6. Decontaminate: autoclave plates and waste; wipe surfaces with 0.5% hypochlorite or an EPA-registered disinfectant effective against Coxiella, respecting contact time. 7. Preserve records: the email, SOP, bench log, PPE records, and exposure list. Do not assign blame in the first communication. Post-exposure prophylaxis decisions belong to occupational health and infectious disease; doxycycline is standard for nonpregnant adults, and pregnancy requires expert consultation.
2. Perform a root-cause analysis: which controls failed, and what corrective actions would prevent recurrence? Address the SOP, engineering controls, and student eligibility.
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The root cause is not one student's habit; it is a chain of failed controls. The risk assessment was absent: abortion material from ruminants is a classic Q fever and brucellosis risk and should trigger a high-consequence review before culture. The SOP classified livestock specimens as BSL-2 without an aerosol caveat; that may be appropriate for many clinical samples but not for propagating a potential BSL-3 agent. Engineering controls failed: no biosafety cabinet, an open bench, and sniffing tolerated as customary. Administrative controls failed: no screening question about abortion storms or farm illness, no exclusion criteria for pregnant or immunosuppressed students, and no training on aerosol risk.
Corrective actions: revise the SOP to require a risk assessment for placental and abortion material and to route culture to a biosafety cabinet or a reference laboratory; ban sniffing; require a specimen history form; add a pre-lab briefing; define student eligibility and accommodation; stock respirators and fit-test those who need them; and establish a relationship with a BSL-3 reference laboratory. Verify effectiveness by auditing 10 consecutive livestock specimens and by running a mock exposure drill.
3. How would you preserve the learning objective of the exercise while eliminating the aerosol hazard in future cohorts?
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Keep the learning objective, which is recognizing zoonotic risk and interpreting culture results, without culturing a select agent. Use a case-based exercise built on the actual farm scenario: students read the history, decide what risk assessment is needed, and choose the biosafety level and PPE. Provide nonviable antigen, stained slides, or a commercial inactivated preparation for microscope work. Use a virtual bench or a video of a BSL-3 reference laboratory processing the specimen. Teach the difference between handling clinical specimens for direct testing and propagating organisms, which is where aerosol risk escalates.
Add a short module on Q fever: transmission, at-risk occupations, pregnancy, and the fact that a low infectious dose makes sniffing plates a high-risk behavior. Assess with a written risk-assessment exercise and a verbal briefing rather than live culture. If the program wants a live culture, use a non-zoonotic organism such as a purchased nonpathogenic E. coli or a yeast, and keep the zoonotic case as a separate discussion. This preserves rigor and removes the hazard.