‘Unusual’ exposures identified among HCP in M. tuberculosis outbreak
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A tuberculosis outbreak, which was linked to a viable bone allograft product contaminated with Mycobacterium tuberculosis, resulted in ”unusual” exposures for health care personnel, according to the outbreak investigation.
“This contact investigation was conducted as part of the investigation of a nationwide tuberculosis (TB) outbreak linked to a contaminated bone graft product,” Janet Glowicz, PhD, RN, nurse infection preventionist with the CDC’s Hospital Infection Prevention Team, told Healio.
“One hundred and thirteen patients that received the bone graft were considered to have potentially transmissible TB. The contact investigation sought to identify health care personnel (HCP) that may have acquired TB through exposure to these patients,” Glowicz said.
On June 8, 2021, the CDC recommended contact investigations with post-exposure testing in health care settings where the 113 patients received treatment.
Based on observations of patient care during the initial cluster investigation, the CDC narrowed down exposed HCP to those present during surgical implantation with the contaminated bone graft, revision surgeries or during provision of inpatient or outpatient medical care, during which they had contact with patients with infectious TB without taking proper precautions.
According to the study, the CDC provided an outbreak-specific health care risk assessment to help identify potentially exposed HCP and recommended screening for HCP with no known history of TB disease or latent TB infection (LTBI), a tuberculin skin test or interferon-gamma release assay.
State health departments shared HCP contact investigation data received from 31 of the 35 acute-care or ambulatory surgical centers that had performed the initial bone graft implantations, of which 26 reported the locations of HCP exposures.
As of April 2022, 4,884 HCP had been screened, with 73 (1.5%) testing positive for LTBI infection, all of whom reported prior negative testing for M. tuberculosis infection, according to the investigation.
The investigation revealed that at least 15 of the 73 reported infections resulted from “unusual extrapulmonary exposures,” including draining tuberculous wounds and “grossly contaminated” procedural and surgical equipment.
Investigators determined that some HCP were exposed to contaminated bone allograft during surgery, whereas others were potentially repeatedly exposed during patient care and preparation activities, including stirring graft matrix in an open container before surgical implantation, irrigating infected surgical wounds during revision surgeries, rigorous flushing and brushing of cannulated surgical instruments during decontamination, generating a forceful stream of surgical wound drainage to empty drains and flushing liquid drainage in an open hopper.
Moreover, the study found that either not using or intermittently using transmission-based precautions during wound and routine care of patients with draining tuberculous surgical wounds resulted in additional exposures.
“Health care personnel should always follow CDC guidance for transmission-based precautions to prevent the spread of TB. Airborne precautions with the use of respiratory protection and a negative pressure room for TB plus contact precautions when TB bacteria may be present in draining wounds are recommended,” Glowicz said.
“A thorough contact investigation is a cornerstone of TB elimination. Identification of infection following exposure and treatment prior to development of symptoms halts the spread of TB,” she said.
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