If you’ve ever had to take antibiotics, the chances are you’ve experienced the down-side as well as the benefits. Diarrhoea is a well-recognised problem of antibiotic treatment, and is thought to arise because of an upset in the bacteria that normally live in our intestine – the gut microbiota.
In the search for a solution to antibiotic-associated diarrhoea (AAD), research is focusing on clarifying the role of probiotics in helping to restore the natural balance in the gut microbiota and so prevent the unwelcome effect. Probiotics are ‘friendly’ microbes – live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.
Yogurt naturally contains two strains of microbes that are used in the fermentation of milk to yogurt (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus). But yogurt also makes a perfect vehicle for adding further potentially helpful microbes, or probiotics.
Some probiotic strains may help to prevent AAD in adults and children, but few studies have looked specifically at the potential benefits in hospitalised patients. People who are in hospital are particularly susceptible to AAD because they may be debilitated by more than one illness.
One of the largest clinical trials on probiotics and AAD in adults
The authors of this study recruited 314 people, mostly elderly, who were prescribed antibiotics (amoxicillin-clavulanate or levofloxacin) in a Spanish hospital. The study looked at the effects on the occurrence of AAD of standard yogurt compared with yogurt supplemented with additional probiotics.
The participants were randomly assigned to receive a cup of yogurt drink supplemented with three strains of probiotic, or standard yogurt that did not contain the additional strains. A third group didn’t receive any yogurt and so formed a control.
Each participant started the ‘treatment’ within 48 hours of beginning the course of antibiotic and continued until 5 days after stopping the antibiotic. The participants were followed up for a month to see if they suffered any episodes of diarrhoea.
Rate of diarrhoea were similar with or without the probiotic
Results suggested that neither the probiotic yogurt nor standard yogurt appeared to prevent AAD.
During the one-month follow-up, 23% of participants in the probiotic-supplemented yogurt group suffered diarrhoea compared with 17.6% in the standard yogurt group – a difference that was not statistically significant. The severity of diarrhoea was also similar in the two groups. And there wasn’t much difference between rates of diarrhoea in the yogurt groups and the control group.
‘…our study does not support a role of the combined probiotic strains L. acidophilus LA-5, B. lactis BB-12 and L. casei LC-01 in the prevention of AAD in hospitalized (mostly elder) patients.’ – Velasco et al, 2018.
The type of probiotic could be key to success
The strains of supplemented probiotic used in this study were Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus casei subsp. casei LC-01).
These probiotic strains were found to be sensitive to the antibiotics taken by the participants in this study, and this might have contributed to the apparent lack of benefit. It is possible that not enough of the probiotic survived in the gut to have an effect on AAD, say the authors.
Previous studies have suggested that other probiotic strains do have positive effects when it comes to AAD prevention. It would be well worth conducting more studies of specific probiotic strains in AAD prevention in different clinical settings, say the authors.
Evidence also suggests that probiotics may be less effective at preventing AAD in the elderly. More studies on probiotics and AAD are needed in older hospitalised patients before any firm conclusions can be drawn, say the authors.
‘Up to now, Lactobacillus rhamnosus GG and Saccharomyces boulardii are the only species that have demonstrated a protective effect on AAD in children and adult patients.’ – Velasco et al, 2018.