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.
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
Lack of capacity to provide informed consent, refusal to participate, or withdrawal of informed consent
The study population comprises 120 individuals with a confirmed diagnosis of cystic fibrosis recruited from multiple centers in Germany. Participants include both adults and minors (with consent from legal guardians) and are divided equally into a case group of patients with a current or prior pulmonary NTM infection and a control group of patients without a known history of NTM infection. All participants provide written informed consent, and clinical data and isolates are obtained exclusively from routine care.
Case-control
Prospective
Multi-modal NTM diagnostic including PCR, WGS, culture
Other interventionEnvironmental samples from participants' households (e.g., water, dust, and soil) will be collected and tested for the presence of NTM. Analyses will be performed using PCR, culture-based methods, whole-genome sequencing (WGS), and subsequent bioinformatic analyses. In addition, available clinical NTM isolates from previous or future routine diagnostics will be included. If genomic sequencing has not yet been performed for these isolates, retrospective molecular genetic analysis (e.g., by WGS) will be conducted within the study to enable comparison with environmental isolates.
Prevalence of NTM in environmental samples
Proportion of households of CF patients with and without NTM infection in which at least one (clinically relevant) NTM is detected in environmental samples (water, dust, soil).
Difference in NTM prevalence between case and control groups
Statistically significant difference in the frequency of NTM detection (clinically relevant and/or all NTM) in environmental samples between case group and control group.
Genetic concordance between environmental and patient isolates
Evidence of genetic relatedness (e.g., cgMLST clustering) between NTM detected in the household environment and clinical isolates from the same individual.
Characterization of NTM species from environmental samples
Identification and taxonomic classification of NTM isolates using WGS, including typing (e.g., subspecies assignment for M. avium).
Identification of environmental and behavioral factors associated with NTM detection
Determination of significant risk factors (e.g., use of specific water sources, pet ownership, hygiene practices) based on questionnaire data and multivariable analyses.
Long-term outcomes (control group only)
Proportion of patients without an initial NTM infection who develop a clinically relevant NTM infection during the follow-up period (up to 30 months), potentially in association with prior detection of NTM in the household environment.
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