“It is great that we have antibiotics which help us fight infections, as this saves many lives. At the same time, it is important to investigate the possible disadvantages with the use of antibiotics. In our new study, we have investigated how different antibiotics can be linked to short-term and long-term changes in the gut microbiota,” says Marju Orho-Melander, professor of genetic epidemiology at Lund University Diabetes Centre.
Previous research has reported alterations in the gut microbiome shortly after antibiotics treatment, but the long-term consequences have largely been unknown. In observational studies, use of antibiotics has been associated with an increased risk of obesity, type 2 diabetes, cardiovascular disease, and cancer.
Mapping of gut microbiota
Marju Orho-Melander has collaborated with Tove Fall, principal investigator of the study at Uppsala University, on the article which investigated how the gut microbiota is affected by antibiotic use. The researchers analysed drug register data and did a detailed mapping of the gut microbiota of 14,979 participants living in Sweden. Around 6,000 of the participants were based in Malmö. The researchers compared the gut microbiota between participants who had received different types of antibiotics and those who had not received any during different periods before sampling. The team studied how the species richness and bacteria composition of the gut microbiota may have been affected up to eight years after the use of antibiotics.
“Our findings suggest that it is important to be restrictive with antibiotics as species richness seems to decrease with each treatment, which may affect the gut microbiota for several years. In previous research, decreased species richness in the gut has been linked to several diseases, such as obesity, diabetes and inflammatory bowel diseases,” says Marju Orho-Melander.
Three antibiotics with strong impact
The research team divided antibiotics into eleven classes and found that the three classes clindamycin, fluoroquinolones, and flucloxacillin had the greatest impact on species richness and could be linked to the greatest reduction of species.
Anna Larsson is a doctoral student in Marju Orho-Melander’s research group and one of the co-authors of the article. She is also a general practitioner at a healthcare centre in southern Sweden and follows special recommendations for prescribing antibiotics in her clinical work.
“In this study, we see that several of the types of antibiotics that affect the species richness and composition of the gut microbiota the most are examples of antibiotics that contribute to antibiotic resistance. Many physicians in Sweden are already restrictive about prescribing for example clindamycin and fluoroquinolones, which in our study were among the antibiotics that had the greatest impact on the gut microbiota,” says Anna Larsson.
Penicillin V was linked to minimal effects
An unexpected finding for her was that flucloxacillin, which is a narrow-spectrum antibiotics recommended for the treatment of skin infections, was one of the three antibiotics which had the biggest impact on the gut microbiota. In countries like Sweden, the healthcare system is restrictive when it comes to prescribing antibiotics, compared to some countries where it may be more common to prescribe antibiotics for less serious infections.
“Infections that can have serious consequences if left untreated should always be treated with antibiotics. At the same time, our findings provide increased evidence for prescribing antibiotics with caution. If a physician can choose between two groups of antibiotics, it may be wise to choose the sort that has the least impact on the gut microbiota,” says Anna Larsson.
Penicillin V, which is a recommended choice for the treatment of common infections in Sweden, such as otitis, pneumonia, and tonsillitis, was linked to minimal and short-term effects on the gut microbiome.
Link to the press release about the article on Uppsala University's website
