Broad vs narrow spectrum antibiotics: Which is better for patients with cystic fibrosis?

Broad spectrum (BS) antianaerobic therapy shows greater and even longer-lasting effect on the lung microbiome of patients with cystic fibrosis, without achieving recovery of pulmonary function noted with narrow spectrum (NS) therapy, reports a study.

A team of investigators sought to examine the effect of BS vs NS antianaerobic antibiotic activity on lung microbiome diversity and pulmonary function through pulmonary function tests and respiratory samples obtained prospectively from patients with cystic fibrosis before and after treatment for pulmonary exacerbations. Antibiotics were classified either as BS or NS.

The investigators then used gene sequencing data from 16S rRNA for diversity analysis and bacterial genera classification, as well as compared the effects of BS vs NS on diversity indices, lung function, and anaerobic/aerobic ratios. Multilevel mixed-effects generalized linear models and mixed-effects regression models were used to determine statistical significance.

Twenty patients aged 6–20 years experienced a total of 30 exacerbations. BS therapy demonstrated a greater effect on beta diversity relative to NS therapy when comparing time points from before taking antibiotics to after treatment and at recovery.

On the other hand, the NS therapy group showed a greater turn toward baseline forced expiratory volume at 1 second and forced expiratory flow 25–75 percent values than the BS group following treatment with antibiotics.

In addition, the ratio of anaerobic/aerobic organisms revealed the prevalence of anaerobes in the NS group and the aerobes in the BS group.

“Specific antibiotic therapies may affect disease progression by changing the airway microbiome,” the investigators said.