Nontuberculous mycobacteria infection with CF is increasing

Nearly 8% of cystic fibrosis patients may be infected

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Nearly 8% of people with cystic fibrosis (CF) may be infected with nontuberculous mycobacteria (NTM), a type of bacteria in the environment, a meta-analysis study has found.

Researchers observed that the number of cases has surged across the world over the last few years. The bacteria can cause infection in a range of sites, the most concerning being the lungs.

“Future studies should report screening frequency, microbial identification methods and incidence rates of progression from NTM infection to pulmonary disease,” the researchers wrote in the study, “Global burden of nontuberculous mycobacteria in the cystic fibrosis population: a systematic review and meta-analysis,” which was published in ERJ Open Research.

NTM are a group of bacteria that are related to the bacteria that cause tuberculosis (a serious infection that usually attacks the lungs), but don’t cause tuberculosis. They’re commonly found in soil, dust, and water.

Even though anyone can get an infection, people with a weakened immune system or underlying lung disease are at higher risk of infection.

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For those with CF, this is because their bodies produce an abnormally thick and sticky mucus that can clog their airways and create a breeding ground for bacteria and other germs. This mucus also makes it harder for their immune systems to clear up an infection.

People with CF who have a long-lasting infection with this type of bacteria may have more difficulty breathing and may be disqualified for a lung transplant.

Although NTM are becoming more common in the general population, their prevalence and incidence among CF patients is unknown, leading a team of researchers in Canada to combine data from 95 different studies as part of a meta-analysis. Prevalence refers to the proportion of people with CF who are infected with NTM at a particular point in time and incidence is the number of new cases that occur in the CF population.

Most studies were from Europe (42%) or North America (33%), and almost all (79%) included a mix of children and adults with CF. All studies reported on NTM and 14 reported on lung disease caused by NTM.

Based on 21 studies that included data from 2010-2019, it was estimated that the prevalence of NTM infection was 7.9%. The prediction interval, which is the interval wherein a future observation is most likely to fall, was 1-41.6%.

It appears the estimated prevalence “is increasing over time based on international registry reports,” the researchers wrote.

The most common species of NTM in people with CF are Mycobacterium abscessus complex (MAB) and Mycobacterium avium complex (MAC). The estimated prevalence of infection by MAB was 3.7%. MAC was 4.1% and it was significantly lower in Europe than North America (1.7% vs. 7.8%).

Sample size and geographical location of the study may affect these estimates, however, the researchers said.

“A significant and relatively low-cost way to build upon this work is to create a living systematic review of the NTM burden in CF, which could be updated annually with new registry and observational data to enhance surveillance of trends,” they concluded.

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