Nontuberculous Mycobacterial Pulmonary Infections in a Northeast Mexico Referral Hospital: Trends and Radiological Findings

Abstract INTRODUCTION: Nontuberculous mycobacteria (NTM) are species that do not cause tuberculosis or leprosy. There are over 180 species, some being opportunistic pathogens that can lead to diverse infections The risk of pulmonary NTM disease is influenced by factors such as age, gender, immune status, structural lung diseases, and environmental humidity. Recent studies indicate a rising incidence of NTM infections over the past two decades, with the M. avium complex being the most common species globally. METHODS: We conducted a retrospective review of the records of NTM samples processed in our reference mycobacterial-specialized laboratory in Northeast Mexico, from January 2004 to October 2024. Available medical records and images were also examined. RESULTS: Our center has had 123 patients with pulmonary NTM infection over the past two decades, with case numbers varying from one in 2012 to 15 in 2005 (Figure 1B). Considering the impact of the COVID-19 pandemic, there were six cases in 2021, which decreased to two and four cases in 2022 and 2023, respectively. From January to October 2024, 19 cases have been detected. While many species remain unidentified, we highlight the most commonly identified NTM species (Figure 1A). We reviewed 17 medical records with the required information. The mean age was 50 ± 13 years, 10 (55.5%) were men. Nine patients (52.9%) had a history of tuberculosis infection. All patients had abnormal chest radiographs or CT scans: 11 (64.7%) had cavitations, 10 (58.8%) infiltrates, 6 (35.3%) bronchiectasis, 5 (29.4%) showed tree-in-bud sign, 5 (29.4%) had nodules, and 4 (23.5%) fibrosis. Additionally, two (11.8%) had pleural effusion and one (5.9%) pneumothorax. Regarding anatomical distribution, the affected regions were 11 (64.7%) bilateral, 2 (11.8%) upper lobes, 2 (11.8%) right upper lobe, 1 (5.9%) right hemithorax, and 1 (5.9%) right middle lobe. CONCLUSION: Our study presents the frequency and species distribution of NTM infections at a reference regional center in Northeast Mexico over the past two decades, with a notable increase in cases observed in the past year. Prevalence of history of tuberculosis was high, particularly affecting younger males. Chest imaging showed a wide range of abnormalities consistent with NTM pulmonary disease. The fluctuating frequency of cases and the recent incidence peak underscores the need for ongoing surveillance and further investigation into the factors driving the rising incidence of NTM disease in the North of Mexico and South of the United States.