Environmental Reservoirs of Non-tuberculous Mycobacteria in Cystic Fibrosis Households

Environmental Reservoirs of Non-tuberculous Mycobacteria in Cystic Fibrosis Households: A Case-control Study of Exposure Risk at Home

This multicenter, non-interventional case-control study investigates whether household environmental reservoirs, particularly water systems, are associated with non-tuberculous mycobacterial (NTM) infections in people with cystic fibrosis (CF). Environmental samples from the homes of CF patients with and without NTM infection will be analyzed and genetically compared with available clinical isolates, alongside assessment of environmental risk factors, to improve understanding of exposure pathways and inform future prevention strategies.

This multicenter, non-interventional case-control study investigates whether domestic environmental reservoirs-particularly household water systems-contribute to non-tuberculous mycobacterial (NTM) infections in people with cystic fibrosis (CF). Approximately 120 CF patients from several centers in Germany will be enrolled, including 60 patients with a current or previous pulmonary NTM infection and 60 CF patients without known NTM infection as controls.

Environmental samples (water, dust, and soil) will be collected from participants' households and analyzed for the presence of NTM using culture-based methods, PCR, and whole-genome sequencing. These findings will be compared between case and control households, and genetic similarity between environmental NTM isolates and available clinical isolates from the same patients will be assessed. In addition, standardized questionnaires will capture environmental and behavioral risk factors associated with NTM occurrence.

The study is purely observational and relies on clinical data and isolates obtained through routine CF care, with no additional medical procedures for participants. Over a follow-up period of up to three years, newly occurring NTM infections in initially unaffected patients will be documented. The results aim to improve understanding of environmental exposure risks for NTM in CF and to provide evidence for future prevention strategies and potential guideline recommendations.

Inclusion Criteria:

• Confirmed diagnosis of cystic fibrosis (CF)
• No age restriction (including minors with consent from legal guardians)
• Written informed consent to participate in the study (or consent provided by a legal guardian for minors)
• In the case of an NTM infection: diagnosis according to ATS/IDSA criteria and availability of a clinical NTM isolate

Exclusion Criteria:

• Lack of capacity to provide informed consent, refusal to participate, or withdrawal of informed consent