In February 2020 researchers from the USA published their review on how probiotics can prevent antibiotic-associated diarrhoea, which is a common side effect of antibiotic treatment. It is defined as an unexplained diarrhoea which occurs when antibiotics are being taken. Any antibiotic can potentially cause this type of diarrhoea, but “broad-spectrum antibiotics”, which are poorly absorbed, are more likely to cause it. A “broad-spectrum antibiotic”, eg amoxicillin, clindamycin, is a type of antibiotic which acts against a wide range of disease-causing bacteria which is in contrast to a “narrow-spectrum antibiotic” which is only effective against one specific family of bacteria. Although all age groups are affected by antibiotic-associated diarrhoea, children are particularly at risk because they are often prescribed antibiotics. The rate of diarrhoea associated with antibiotic usage among children is estimated to be approximately 20–35%.
It is known that antibiotics reduce the richness and diversity of the gut microbiome, which continues until well after the antibiotic treatment has finished and gives other pathogens, eg Clostridium difficile, Staphylococcus aureus, the opportunity to colonise. Currently, C. difficile is thought to account for about 20% of all cases of antibiotic-associated diarrhoea. Research has also shown that these changes in the gut microbiome contribute to the development of medical conditions, such as obesity, asthma, and inflammatory bowel disease.
Numerous studies have shown that probiotics are able to prevent antibiotic-associated diarrhoea, and in fact probiotics are now frequently prescribed with antibiotic use. In 2019 a Cochrane review on the use of probiotics to prevent antibiotic-associated diarrhoea in chidren found 33 studies and involved 6,352 youngsters. This review found that probiotics significantly reduced the risk of children developing diarrhoea associated with the use of antibiotics. It was suggested that L. rhamnosus or S. boulardii were the most appropriate for preventing any antibiotic-associated diarrhoea. However, the quality of the evidence was only ranked as moderate due to minor issues with the risk of bias and inconsistency between the types of probiotic strains used.
Mekonnen SA et al. Molecular mechanisms of probiotic prevention of antibiotic-associated diarrhea. Curr Opin Biotechnol. 2020 Feb 19;61:226-234