A national Mycobacterium tuberculosis outbreak caused TB seroconversion in 73 healthcare workers exposed to patients who underwent spinal bone grafts with a contaminated allograph product. None of the healthcare workers developed active infection, and all were successfully treated for this strain of TB, which was not drug resistant, the CDC reported.1 Results from the outbreak investigation were presented recently at the annual meeting of the CDC’s Epidemic Intelligence Service (EIS).
Overall, the contaminated product — made from the femur bone of a deceased donor with undiagnosed TB — infected 81 bone tissue recipients in 37 facilities in 20 states. CDC investigators determined 154 units of “lot A” were shipped to the facilities during March and April 2021. Only this lot and one manufacturer were involved, and the product was recalled.
Ten bone recipients died, with three of the deaths attributed to TB. However, more deaths may have been linked to the bone grafts; details were incomplete on some patients.
Broad Definition of Exposure
No patient contacts were diagnosed with latent TB other than the 73 healthcare workers. Most of the workers were identified through use of a broad CDC definition of an exposure that included:
- those present during graft implantation or other activities, like sterile processing, that could aerosolize TB;
- those who came into contact with patients or contaminated dressings with draining lesions;
- those who came into contact with pulmonary TB patients in the absence of airborne precautions.
“This also involved managing medical waste, such as emptying wound drains, as well as disposing soiled dressings,” said EIS officer Ruoran Li, ScD, MPhil, BA.1 “So many of these result from a lack of recognition that patients with draining TB lesions can transmit M. tuberculosis, but also we observed a lack of access to point-of-care, fit-tested respirators as a result of the COVID-19 pandemic and the responses to it.”
Complicating the investigation, the healthcare exposures to TB occurred not only during the period that products were implanted into patients during surgeries, but also during the subsequent months when patients newly infected with M. tuberculosis sought care in the healthcare system.
Although healthcare worker follow-up is ongoing, the CDC presented contact investigation data on 31 acute care facilities that performed implantation surgeries, which make up 89% of all affected surgical facilities. They received contact investigation data on 15 other healthcare facilities that cared for affected patients, Li said.
In total, 5,985 exposed healthcare personnel were identified, and 82% had been evaluated as of April 2022.
“Overall, 73 healthcare personnel tested positive for latent TB infection, including nine in the operating suite, three in sterile processing department, four in post-anesthesia care units, and 35 in inpatient areas, four in environmental services, and 18 ‘other’ or unknown roles,” Li said. “Overall, 1.5% of healthcare personnel converted, spanning across these different healthcare personnel roles.”
Most HCW Infections in Two Hospitals
Thirty-three infected employees worked in two hospitals in the same healthcare network in Indiana, reported EIS officer Molly Deutsch-Feldman, PhD.2
Eleven bone graft patients were treated at two Indiana hospitals. Deutsch-Feldman analyzed the investigation of these patients.
“Three of the patients developed pulmonary disease and eight had evidence of disease at the surgical site,” Deutsch-Feldman said. “Though infectious TB is usually only considered for patients with pulmonary disease, there is evidence from the literature that there is risk of further transmission of M. tuberculosis from open wounds or drains placed during the surgery.”
Generally, these TB wounds develop a high bacillary load, which is aerosolized easily during medical procedures.
“We reviewed the medical charts of the bone graft recipients to determine their infectious periods, and we reviewed hospital patient logs to determine the patient locations during their infectious periods,” Deutsch-Feldman explained. “We also conducted on-site infection prevention and control observations at the facilities to identify additional locations where exposures may have occurred.”
The Indiana investigators faced challenges with identifying all potentially exposed healthcare workers, as medical records did not capture everyone who entered a patient’s room or provided patient care. Overall, the two facilities performed 11 initial surgeries in March and April 2021, and 11 revision surgeries between March and July 2021.
“During the patients’ infectious periods, there were nine subsequent emergency room visits among the bone graft recipients, and 318 patient days within the facilities,” she said.
Most were inpatient stays, although two patients spent time in the rehabilitation hospital.
“Our infection prevention observations identified several key gaps in airborne isolation practices,” Deutsch-Feldman said. “First, we noted a lack of available N95 respirators for healthcare personnel interacting with patients with TB. Second, there were several instances of improper waste disposal. Wound drainage collected in Jackson-Pratt drains was disposed in toilets, hoppers, or sinks located in common areas, potentially aerosolizing M. tuberculosis particles. Waste was also carried in open containers through facility hallways before being disposed. Lastly, we noted malfunctioning airborne infection isolation rooms, though hospital staff informed us that rooms were regularly checked to ensure proper negative pressure.”
Overall, investigators identified 2,261 healthcare personnel who were exposed to TB at the two Indiana facilities. Of these, 64 had either a documented history of a positive test or refused testing, resulting in 2,197 staff tested. Of these, 33 were newly diagnosed with TB.
Most of the healthcare personnel worked on the inpatient units, but TB conversions were found in a diverse array of workers.
“There were also a number of conversions among healthcare personnel working in the operating room, radiology, the endoscopy staff, the emergency department, the security staff, and the rehabilitation hospital,” Deutsch-Feldman explained. “We identified 15 healthcare personnel whose documented exposures were limited to surgical sites, wounds, or equipment. These employees worked in the operating room, physical therapy, the endoscopy suite, the rehabilitation hospital, the laboratory, and the sterile processing department. We also found evidence that suggests there was transmission from surgical sites, wounds, or grossly contaminated equipment.”
Patients with tuberculous wounds should be considered infectious until the wound heals or they produce three consecutive negative cultures, the CDC recommends.
“That was not the case in June and July of 2021,” Deutsch-Feldman said. “There were still exposures occurring during that time. At the end of July, all patients with continued open wounds were placed on proper airborne precautions.”
Because annual TB infection screening is no longer recommended for most healthcare personnel, limited data were available on the background rate of conversions.
“We can’t compare these 33 to annual testing numbers, but because latent TB infection is a reportable condition in the state of Indiana, we do know that between 2019 and 2021, the state saw between one and three healthcare personnel with newly identified TB infections,” Deutsch-Feldman said.
Risk Factors, Attack Rate
Currently, there is no approved TB test for deceased donors. In light of the outbreak, the American Association of Tissue Banks issued recommendations to screen donors for tuberculosis risk factors,3 including:
- a reported history of TB or TB exposure;
- immunosuppressive medications;
- chronic kidney disease and on hemodialysis or peritoneal dialysis;
- chronic liver disease;
- uncontrolled diabetes;
- born in an area with a high prevalence for TB.
“Out of 113 recipients, 77% had microbiologic or imaging evidence of tuberculosis. For context, the secondary attack rate for tuberculosis after traditional exposure is 1%,” reported EIS officer Alfonso Hernández-Romieu, MD, MPH.4
Forty-nine patients underwent surgery for product-related complications, while others received drug therapy. The extraordinary attack rate is not completely understood, but emerging theories exist. “We have several hypotheses, [including] how high the mycobacterial load was in the product itself,” Hernández-Romieu said. “Normally, any clinical specimen positive culture will take up to six to eight weeks, whereas in this particular product, it took about two weeks to grow. There was a very high burden of mycobacteria there.”
That bioburden also could have contributed to the occupational infections. Another factor in the patients is that TB was essentially placed directly into the spine, which may have undermined immune reactivity and facilitated spread of the pathogen in the body. “Of those with TB, in 25% of patients, it had disseminated to other body sites, including the lungs and the central nervous system,” Hernández-Romieu said.
A donor screening questionnaire from the tissue donor’s available next of kin indicated the donor had no known history of TB disease, a positive TB test, nor exposure to TB in the previous 12 months, Hernández-Romieu said. However, the donor had TB risk factors, including prior residence and frequent travel to a country with a tuberculosis incidence 8.5 times higher than that of the United States. Other risk factors included older than age 80 years, a type 2 diabetes diagnosis, and end-stage renal disease and receiving hemodialysis.
REFERENCES
- Li R, Deutsch-Feldman M, Hernández-Romieu A, et al. Unusual healthcare personnel exposures to Mycobacterium tuberculosis related to a contaminated surgical product — United States, 2021. CDC Epidemic Intelligence Service Conference. May 5, 2022.
- Deutsch-Feldman M, Li R, Romieu-Hernández A, et al. Extrapulmonary transmission of Mycobacterium tuberculosis to health care personnel exposed to bone graft recipients — Indiana, 2021. CDC Epidemic Intelligence Service Conference. May 5, 2022.
- American Association of Tissue Banks. AATB recommendation issued to tissue banks regarding the risk of Mtb transmission. March 22, 2022.
- Hernández-Romieu A, Schwartz N, Wilson W, et al. Spinal and disseminated tuberculosis caused by surgical implantation of a bone tissue product — 20 U.S. states, 2021. CDC Epidemic Intelligence Service Conference. May 5, 2022.
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