Achromobacter Infection in Children Linked to Worse Lung Function
Infection with the environmental bacteria Achromobacter in children with cystic fibrosis (CF) is linked with poorer lung function and more pulmonary exacerbations, a study suggests.
These findings highlight the need to identify Achromobacter infection promptly so that children can receive appropriate treatment.
“Our results may indicate that Achromobacter [species] begin to colonize at earlier ages than we expected,” the researchers wrote.
The study, “Impact of Achromobacter spp. isolation on clinical outcomes in children with cystic fibrosis,” was published in the journal Pediatric Pulmonology.
Bacterial infections are one of the most common causes of impaired lung function in CF patients. Staphylococcus aureus and Haemophilus influenzae are the two most prevalent bacteria isolated from the lungs of children with CF. Meanwhile, infection with Pseudomonas aeruginosa, called P. aeruginosa, is more common later in life. Like P. aeruginosa, the Achromobacter bacteria is commonly found in the environment, and can live in water or soil.
According to researchers, opportunistic bacteria — ones that only cause disease in certain circumstances — including the Achromobacter species, are increasingly being detected in CF patients. However, this bacteria can be misidentified as P. aeruginosa by non-specialized CF labs due to similarities in bacteria shape.
This suggests that the prevalence of Achromobacter in CF, previously reported to range from 3% to 30%, may be underestimated. Moreover, the majority of studies were conducted in CF adults, so the burden and impact on lung health in children remains largely unknown.
To learn more, researchers at the School of Medicine, Hacettepe University, in Turkey reviewed data of 350 CF children followed at their center from 2011 to 2019.
“To our knowledge, this is the first study showing the effect of Achromobacter spp. on pulmonary function in only the pediatric population with CF,” the researchers wrote.
Of the 350 children, 37 (10.5%) were positive for Achromobacter at least once during their follow-up. As controls, the team included age, sex, and P. aeruginosa status-matched CF children who were negative (or had been for at least a year) for Achromobacter.
Among those with Achromobacter, the bacteria were present as a chronic infection in 15 children (40.5%; median age at detection 8.7) and intermittently in 22 participants (59.5%; median age at detection 6.8).
P. aeruginosa was detected in a total of 28 children across both groups, the controls and those positive for Achromobacter. In the remaining seven children (25%), P. aeruginosa was only isolated once at the time of detection of Achromobacter.
During the study, no participants died or underwent a transplant. More than half (65%) of the children positive for Achromobacter had no complaints. Physical examinations — routine evaluations are done every three months at the clinic — were normal in 71.9%.
In all, 18 children with Achromobacter (48.6%) received treatment, with five (27.7%) given intravenous (into-the-vein) antibiotics. No differences were seen between those with chronic and intermittent infection.
The team compared lung function and exacerbation frequency between both groups. Exacerbations are characterized by rapid disease worsening, leading to decreased lung function and an increased risk of mortality.
Spirometry, the most common type of pulmonary function or breathing test, was performed for 24 children (64.8%) in the Achromobacter and 28 (75.6%) in the control group.
At the study’s start (baseline), forced expiratory volume in one second — FEV1; a measure of how much air can be exhaled in one second after a deep inhaled breath — and forced vital capacity or FVC, the amount of air that can be forcibly exhaled from the lungs after taking the deepest breath possible, did not differ significantly between the two groups. The two measures were adjusted for age, height, sex, and ethnicity.
By the end of the first year of follow-up, the decline in FEV1% was significantly greater in the Achromobacter group compared with controls (9.07% vs. 1.18%). A similar result was seen for the annual decline in FVC%, with a greater decline in the group with the bacterial infection, but this did not reach a statistically significant difference.
Children with chronic infection had significantly lower z-scores in FEV1 and FVC than those with intermittent infections. No differences were seen in annual lung function decline by the end of the first year between these groups.
Of note, a z-score reflects where a given result stands relative to the mean in a reference population.
The researchers identified Achromobacter as an independent predictor of the annual decline in lung function.
The median number of annual pulmonary exacerbations was significantly higher in the Achromobacter group than in the controls. Within the Achromobacter group, no differences were seen between intermittent and chronic infection.
Patients co-infected with Achromobacter and P. aeruginosa showed no differences in pulmonary function and exacerbation frequency compared with those with Achromobacter alone.
Overall, this study suggests that in children with CF, infection with this bacteria “is associated with more accelerated decline in lung function parameters and frequent exacerbations,” the researchers wrote.
“Healthcare professionals should pay attention to treating symptomatic Achromobacter spp. [species] infection,” they concluded.