P-777. Assessment of Epidemiologic Case Definitions for Disseminated Nontuberculous Mycobacterial Disease in Patients Without AIDS
Authors: Jackson Kelly A , Byram Rebecca , Czaja Christopher A , Johnston Helen , Orten Kelsey T , Lynfield Ruth , Centurion Nathan , Tourdot Laura , Vagnone Paula Snippes , Dumyati Ghinwa , Myers christopher J , O’Brien Shannon C , Mansour Adel M , Prevots D Rebecca , Winthrop Kevin L , Toney Nadege Charles , Magill Shelley , See Isaac 
Published: January 2025

Abstract

Background
Disseminated Mycobacterium avium complex (MAC) infection rates have declined in persons with HIV; some studies report increasing numbers of disseminated nontuberculous mycobacteria (NTM) infections in other groups of immunocompromised persons. However, no consensus definition exists for disseminated NTM in these populations. We compared characteristics of disseminated NTM in persons without AIDS using different epidemiologic definitions.Table 1.Disseminated nontuberculous mycobacteria definitions..

Methods
CDC’s Emerging Infections Program conducted active, laboratory- and population-based NTM surveillance in 4 states (11 counties) during 2021–2022 to identify patients with NTM in clinical specimens, excluding stool or rectal swabs. Clinical and laboratory data were collected via medical record review. Disseminated NTM definitions are shown in Table 1. We determined the numbers of patients without AIDS who met each definition. Among those meeting each definition we calculated the percentages of patients with: 1) selected immunocompromising conditions; 2) MAC infection; and 3) documented clinical diagnosis of any NTM infection (i.e., NTM not likely to represent contamination or colonization).Figure 1.Number of patients meeting each disseminated nontuberculous mycobacteria definition, Emerging Infection Program, 2021–2022 (N=59).

Results
Among 877 patients with NTM and without AIDS, 15 patients (1.7%) had a documented disseminated NTM clinical diagnosis (definition 1); 59 (6.7%) met ≥1 of the 3 definitions. Although more patients met definition 2 (31, 3.5%) or definition 3 (53, 6.0%) than definition 1, definition 2 only captured 10/15 (66.7%) patients with a documented disseminated NTM clinical diagnosis; definition 3 captured only 9/15 (60.0%) (Figure 1). The proportion of patients with malignancy, immunosuppressive medication, or transplant differed by definition as did the proportion infected with MAC. Seven of 31 patients meeting definition 2 (22.6%) and 14/53 (26.4%) patients meeting definition 3 did not have a clinician documented diagnosis of any NTM infection in the medical record (Figure 2).Figure 2.Proportion of patients with malignancy(a), immunosuppressive medication(b), transplant(c), isolation of M. avium complex, or clinical diagnosis of any type of nontuberculous mycobacteria infection(d), stratified by disseminated NTM definition, Emerging Infections Program, 2021–2022.

Conclusion
Each disseminated NTM definition identified a different group of patients, limiting their usefulness and comparability. Development of a standard epidemiologic definition for disseminated NTM in persons without AIDS will enable better understanding of disease impact in susceptible populations.

Disclosures
Kevin L. Winthrop, MD, MPH, AN2: Advisor/Consultant|AN2: Grant/Research Support|Insmed: Advisor/Consultant|Insmed: Grant/Research Support|Mannkind: Advisor/Consultant|Mannkind: Grant/Research Support|Paratek: Advisor/Consultant|Paratek: Grant/Research Support|Renovion: Advisor/Consultant|Renovion: Grant/Research Support|Spero: Advisor/Consultant|Spero: Grant/Research Support