The frequent use of antimicrobial (AM) drugs in the first decade of life shifts bacterial profiles in saliva, according to the Finnish Health in Teens (Fin-HIT) study, conducted by researchers at the University of Helsinki.
The cohort study involved more than 11,0000 Finnish adolescents, and the researchers used data from 808 children randomly selected from this pool with objective register data on AM purchases from the Social Insurance Institution of Finland (KELA).
On average, these children had 7.4 AM purchases during their lifespan until an average of 12 years. The four most commonly used AMs were amoxicillin (43.7%), azithromycin (24.9%), amoxicillin-clavulanate (18.7%), and phenoxymethylpenicillin (6.8%).
Frequent use of AM drugs shifted bacterial profiles in saliva, the researchers said, with the frequent use of any AMs affecting saliva microbiota.
“Microbial composition different between high, medium, and low users of AMs. These effects are also gender- and AM-dependent,” said Sajan Rajo, postdoctoral researcher at the university.
For example, azithromycin is used for middle ear infections, strep throat, and pneumonia, yet it had the strongest associations with shifts in bacterial profiles. Each course decreased microbiota diversity, and this change was observed more in girls than boys.
“Our findings emphasize a concern for high azithromycin use, which substantially impaired the bacterial diversity and affected composition as well,” said Raju.
In boys, amoxicillin affected microbial composition more than in girls. Like azithromycin, amoxicillin is widely used for middle ear infections and strep throat. The use of amoxicillin and amoxicillin-clavulanate was associated with the largest decrease in abundance of the Rikenellaceae family.
AM use in general was associated with a decrease of Paludibacter and pathways related to amino acid degradations.
However, the researchers said, the contribution of lifelong AM use on saliva microbiota is unknown, and AM use might have unforeseen health impacts in the future.
“It can have health impacts such as inducing obesity or antibiotic resistant bacteria,” said Raju.
Most of the children in the study, 85%, were exposed to AMs during the first three years of their life. The researchers could not confirm that the purchased AMs were taken, though. Also, the study did not assess the oral health of the children involved in the study.
The study, “Antimicrobial Drug Use in the First Decade of Life Influences Saliva Microbiota Diversity and Composition,” was published by Microbiome.