Antibiotics alter the microbial balance commonly resulting in antibiotic‐associated
diarrhea (AAD). Probiotics may prevent AAD via providing gut barrier, restoration
of the gut microflora, and other potential mechanisms of action. The primary objectives
were to assess the efficacy and safety of probiotics (any specified strain or dose)
used for the prevention of AAD in children. MEDLINE, Embase, CENTRAL, CINAHL, and
the Web of Science (inception to 28 May 2018) were searched along with registers including
the ISRCTN and Clinicaltrials.gov. We also searched the NICE Evidence Services database
as well as reference lists from relevant articles. Randomized, parallel, controlled
trials in children (0 to 18 years) receiving antibiotics, that compare probiotics
to placebo, active alternative prophylaxis, or no treatment and measure the incidence
of diarrhea secondary to antibiotic use were considered for inclusion. Study selection,
data extraction, and risk of bias assessment were conducted independently by two authors.
Dichotomous data (incidence of AAD, adverse events) were combined using a pooled risk
ratio (RR) or risk difference (RD), and continuous data (mean duration of diarrhea)
as mean difference (MD), along with corresponding 95% confidence interval (95% CI).
We calculated the number needed to treat for an additional beneficial outcome (NNTB)
where appropriate. For studies reporting on microbiome characteristics using heterogeneous
outcomes, we describe the results narratively. The certainty of the evidence was evaluated
using GRADE. Thirty‐three studies (6352 participants) were included. Probiotics assessed
included Bacillus spp., Bifidobacterium spp., Clostridium butyricum , Lactobacilli
spp. , Lactococcus spp., Leuconostoc cremoris , Saccharomyces spp., or Streptococcus
spp., alone or in combination. The risk of bias was determined to be high in 20 studies
and low in 13 studies. Complete case (patients who did not complete the studies were
not included in the analysis) results from 33 trials reporting on the incidence of
diarrhea show a precise benefit from probiotics compared to active, placebo or no
treatment control. After 5 days to 12 weeks of follow‐up, the incidence of AAD in
the probiotic group was 8% (259/3232) compared to 19% (598/3120) in the control group
(RR 0.45, 95% CI 0.36 to 0.56; I² = 57%, 6352 participants; NNTB 9, 95% CI 7 to 13;
moderate certainty evidence). Nineteen studies had loss to follow‐up ranging from
1% to 46%. After making assumptions for those lost, the observed benefit was still
statistically significant using an extreme plausible intention‐to‐treat (ITT) analysis,
wherein the incidence of AAD in the probiotic group was 12% (436/3551) compared to
19% (664/3468) in the control group (7019 participants; RR 0.61; 95% CI 0.49 to 0.77;
P <0.00001; I² = 70%). An a priori available case subgroup analysis exploring heterogeneity
indicated that high dose (≥ 5 billion CFUs per day) is more effective than low probiotic
dose (< 5 billion CFUs per day), interaction P value = 0.01. For the high dose studies
the incidence of AAD in the probiotic group was 8% (162/2029) compared to 23% (462/2009)
in the control group (4038 participants; RR 0.37; 95% CI 0.30 to 0.46; P = 0.06; moderate
certainty evidence). For the low dose studies the incidence of AAD in the probiotic
group was 8% (97/1155) compared to 13% (133/1059) in the control group (2214 participants;
RR 0.68; 95% CI 0.46 to 1.01; P = 0.02). Again, assumptions for loss to follow‐up
using an extreme plausible ITT analysis was statistically significant. For high dose
studies the incidence of AAD in the probiotic group was 13% (278/2218) compared to
23% (503/2207) in control group (4425 participants; RR 0.54; 95% CI 0.42 to 0.70;
P <0.00001; I² = 68%; moderate certainty evidence). None of the 24 trials (4415 participants)
that reported on adverse events reported any serious adverse events attributable to
probiotics. Adverse event rates were low. After 5 days to 4 weeks follow‐up, 4% (86/2229)
of probiotics participants had an adverse event compared to 6% (121/2186) of control
participants (RD 0.00; 95% CI ‐0.01 to 0.01; P < 0.00001; I² = 75%; low certainty
evidence). Common adverse events included rash, nausea, gas, flatulence, abdominal
bloating, and constipation. After 10 days to 12 weeks of follow‐up, eight studies
recorded data on our secondary outcome, the mean duration of diarrhea; with probiotics
reducing diarrhea duration by almost one day (MD ‐0.91; 95% CI ‐1.38 to ‐0.44; P <0.00001;
low certainty evidence). One study reported on microbiome characteristics, reporting
no difference in changes with concurrent antibiotic and probiotic use. The overall
evidence suggests a moderate protective effect of probiotics for preventing AAD (NNTB
9, 95% CI 7 to 13). Using five criteria to evaluate the credibility of the subgroup
analysis on probiotic dose, the results indicate the subgroup effect based on high
dose probiotics (≥ 5 billion CFUs per day) was credible. Based on high‐dose probiotics,
the NNTB to prevent one case of diarrhea is 6 (95% CI 5 to 9). The overall certainty
of the evidence for the primary endpoint, incidence of AAD, based on high dose probiotics
was moderate due to the minor issues with risk of bias and inconsistency related to
a diversity of probiotic agents used. Evidence also suggests that probiotics may moderately
reduce the duration of diarrhea, a reduction by almost one day. The benefit of high
dose probiotics (e.g. Lactobacillus rhamnosus or Saccharomyces boulardii ) needs
to be confirmed by a large well‐designed multi‐centered randomized trial. It is premature
to draw firm conclusions about the efficacy and safety of 'other' probiotic agents
as an adjunct to antibiotics in children. Adverse event rates were low and no serious
adverse events were attributable to probiotics. Although no serious adverse events
were observed among inpatient and outpatient children, including small studies conducted
in the intensive care unit and in the neonatal unit, observational studies not included
in this review have reported serious adverse events in severely debilitated or immuno‐compromised
children with underlying risk factors including central venous catheter use and disorders
associated with bacterial/fungal translocation. Probiotics for the prevention of antibiotic‐associated
diarrhea in children What is antibiotic‐associated diarrhea? Antibiotic‐associated
diarrhea (AAD) occurs when antibiotics disturb the natural balance of "good" and "bad"
bacteria in the intestinal tract causing harmful bacteria to multiply beyond their
normal numbers. The symptoms of AAD include frequent watery bowel movements and crampy
abdominal pain. What are probiotics? Probiotics are found in dietary supplements or
yogurts and contain potentially beneficial bacteria or yeast. Probiotics may restore
the natural balance of bacteria in the intestinal tract. What did the researchers
investigate? The researchers investigated whether probiotics prevent AAD in children
receiving antibiotic therapy and whether probiotics causes any harms (side effects).
The researchers searched the medical literature extensively up to May 28, 2018. What
did the researchers find? Thirty‐three studies were reviewed and provide the best
available evidence. The studies tested 6352 children (3 days to 17 years of age) who
were receiving probiotics co‐administered with antibiotics to prevent AAD. The participants
received probiotics ( Lactobacilli spp., Bifidobacterium spp., Streptococcus spp.
, or Saccharomyces boulardii alone or in combination), placebo (pills not including
probiotics), other treatments thought to prevent AAD (i.e. diosmectite or infant formula)
or no treatment. The studies were short‐term, ranging in length from 5 days to 12
weeks. Analyses showed that probiotics are effective for preventing AAD. The incidence
of AAD in the probiotic group was 8% (259/3232) compared to 19% (598/3120) in the
control group, demonstrating a moderate reduction (11% fewer will suffer diarrhea).
For every 9 children treated, probiotics will prevent one case of diarrhea. Further,
evidence suggests that higher dose probiotics (≥ 5 billion CFUs per day) reduce the
incidence of AAD. Eight per cent (162/2029) of the high dose probiotics group had
AAD compared to 23% (462/2009) in the control group, demonstrating a moderate to large
reduction (15% fewer suffer diarrhea). Probiotics were generally well tolerated, and
minor side effects (e.g. rash, nausea, gas, flatulence, abdominal bloating, constipation)
occurred infrequently. . Evidence suggested that probiotics are effective for a moderate
reduction in duration of diarrhea (almost one day). Among the various probiotics evaluated,
Lactobacillus rhamnosus or Saccharomyces boulardii at 5 to 40 billion colony forming
units/day appear most appropriate for preventing AAD in children receiving antibiotics.
It is premature to draw conclusions about the effectiveness and safety of 'other'
probiotic agents for preventing AAD. Although no serious probiotic‐related side effects
were observed among the mostly otherwise healthy children who participated in the
studies, serious side effects have been reported in observational studies not included
in this review, including severely debilitated or immuno‐compromised children with
underlying risk factors including central venous catheter (a flexible tube used to
give medicines) use and disorders associated with bacterial or fungal translocation
(the passage of bacteria from the gut to other areas of the body).