An incident response ensued. University officials found that the stockroom freezer where the P. shigelloides was stored also, for some inexplicable reason, held a vial labeled N. meningitidis.

University officials determined that 33 people linked to the lab class had been exposed. They called in state public health officials, who quickly helped with risk assessments and sample testing, made public health recommendations, and helped with the investigation.

Incident response

The health officials recommended that all the exposed people start taking post-exposure prophylactic antibiotics for 10 days. Of the 33 exposed, all but one person started on antibiotics. Health officials noted that 15 of the 33 (45 percent) had gotten at least one meningococcal vaccination previously. Still, two people developed headaches and sought emergency care; they were given spinal taps to rule out N. meningitidis infection.

Several days later, the state’s public health laboratory obtained two samples from the ill-fated lab experiment. They used mass spectrometry and whole-genome sequencing to conclusively identify the mystery bacterium: N. sicca, a nonpathogenic relative of N. meningitidis.

The state lab repeated the carbohydrate fermentation tests that the lab students had used to identify the germ as N. meningitidis. The state lab reproduced their results. They concluded that this odd N. sicca isolate was an “atypical carbohydrate fermenter” that threw off the identification, leading not only to the exposure scare but also to the original misidentification on the vial in the stockroom freezer.

While everyone was safe in the end, the class did experience quite a scare and underwent unnecessary interventions. State and federal health officials conducted a subsequent investigation to figure out how a thought-to-be-dangerous pathogen was stored in the same freezer as harmless bacteria for lab classes and how the two got mixed up.

“The investigation found inadequate inventory controls for identifying, labeling, storing, and segregating biological materials according to handling practices and containment conditions,” officials reported. “Additional practice gaps included limited stockroom employee supervision, inadequate availability and use of personal protective equipment, and insufficient documentation of sample inventory, disposition, and chain of custody.”

The officials reported that the findings prompted the university to overhaul their procures and protocols.