351 - Outbreak of Non-Tuberculous Mycobacterial (NTM) Infections in a pediatric dental clinic due to contaminated water

Outbreaks of non-tuberculous mycobacterium (NTM) infections in dental clinics have been linked to poor dental unit water quality, and adherence to best-practice recommendations is inconsistent.  

Objective: An outbreak investigation was launched March 2022 after 3 patients of Dental Clinic A were seen at the same hospital system for subacute jaw swelling following dental procedures. We sought to identify additional cases, confirm likely sources and pathogen, prevent further infections, and develop treatment and prevention recommendations.

Design/Methods: State and local health departments conducted active case finding by contacting families of children who underwent pulpotomy, pulpectomy, extraction, or crown placement at Dental Clinic A from January 2021 to March 2022. The epidemiology teams interviewed families by phone, using paper and web-based surveys; documenting information on demographics, clinical providers, procedures, and illness. A confirmed case was defined as a child with facial and/or neck swelling or lymph node enlargement and/or pathologic evidence of granulomatous inflammation following a dental procedure. Culture and PCR were performed on clinical specimens.  Per public health recommendations, the dental practice consulted with a private laboratory to conduct water cultures in the facility. 

Results: Of 787 families contacted for interview, 483 (61%) completed surveys. From these, 13 total cases were identified. The median time from index dental procedure to symptom onset was 136 days (range, 27-267). Seven cases had evidence of invasive disease: 5 (71%) had mandibular osteomyelitis, 2 (29%) had pulmonary nodules and 1 (14%) had both. Ten (77%) had a surgical procedure for diagnosis and/or management; 9 of these had granulomatous inflammation on pathologic examination. All tissue specimen were culture and PCR negative, but one was AFB smear positive.  Environmental testing at Dental Clinic A found greater than 500 CFU/mL of mycobacteria, including Mycobacterium chelonae/abscessus group and Mycobacterium mucogenicum-phocaicum group in water sampled from multiple delivery systems.

Conclusion(s): Cases in this outbreak had milder presentations than those reported in prior pediatric dental NTM outbreaks. However, significant healthcare burdens, including exposures to antibiotics, imaging and surgery were experienced by affected children. Similar NTM outbreaks in children following dental procedures are preventable with adherence to water quality guidelines, including routine testing and remediation, and use of sterile water for procedures involving pulp exposure.