De los Profesores

Probiotics have several health benefits. They include prevention and treatment of antibiotic-associated diarrhoea, pathogen-induced diarrhoea,^69,70urogenital infections⁷¹ and atopic diseases.^63,72 A variety of probiotics have been evaluated for their efficacy as a means of treating and preventing antibiotic-associated diarrhoea. At least two systematic reviews suggest that probiotics including several bacterial species and the yeast Saccharomyces boulardii effectively reduce the incidence of diarrhoea in patients who take antibiotics.⁶⁹ A careful met-analysis by D’souza et al found that probiotics were more effective than placebo.⁷³ Diarrhoea caused by Clostridium difficile is a common problem associated with antibiotic use especially cephalosporins, amoxicillin, ampicillin and clindamycin.⁶⁹ It causes nearly 25% of cases of antibiotic-associated diarrhoea making it the most commonly identified and treatable pathogen found in this condition.^69,73 Metronidazole and vancomycin are usually effective but recurrences are common.⁷² Probiotics have been proven useful for both preventing and treating antibiotic-associated diarrhoea.⁶⁹ Probiotics have been proven to shorten the duration of diarrhoea episodes especially those caused by infectious agents.^63,64

A prospective study in the United States of 604 children aged 3-36 months in community settings before the introduction of rotavirus vaccine noticed a median duration of 2 days.⁷⁵ This study did not report the severity of the diarrhoea and was done in a presumably high income area as compared to the study done by Lamberti and colleagues which assessed the duration and severity of diarrhoea in low and middle income countries. They noticed that in under 5’s,

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64.8% of diarrhoea episodes were mild, 34.7% were moderate and 0.5% were severe. The duration of the mild episodes lasted averagely 4.3 days and severe episodes lasted averagely 8.4 days and caused dehydration in 84.6% of cases.⁷⁶

The duration of diarrhoea together with other symptoms like fever, abdominal pain and vomiting largely depends on the causative infectious agent as outlined below.

Organism Incubation Duration Vomiting Fever Abdominal

pain

Rotavirus 1-7d 4-8d Yes No Low

Adenovirus 8-10d 5-12d Delayed No Low

Norovirus 1-2d 2d Yes No No

Astrovirus 1-4d 4-8d +/- No +/-

Calicivirus None 4-8d No No +/-

Aeromonas species 2-4d 0-2weeks No No +/-

Campylobacter species

Variable 5-7d Mild No Yes

C difficile Minimal variable No Few Few

C perfringens 1-8d 1d Yes Yes No

Enterohemorrhagic E coli

1-3d 3-6d +/- Yes +/-

Enterotoxigenic E coli

None 3-5d Yes Yes Low

Plesiomonas species

0-3d 0-2weeks No +/- +/-

Salmonella species 0-2d 2-7d Yes Yes Yes

Shigella species 0-1d 2-5d Yes Yes High

Vibrio species None 5-7d No Yes No

Y enterocolitica None 1-46d No Yes Yes

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Giardia species 2 weeks 1+weeks No Yes No

Cryptosporidium species

5-21d months No Yes Low

Entamoeba species 5-7d 1-2+weeks No No Yes

Table 2.1: causative agents of diarrhoea and associated symptoms.⁷⁶

A Cochrane review examined 23 studies (n=1917) that used different types of probiotics to treat acute infectious diarrhoea. The reviews concluded that probiotics significantly reduced the duration of diarrhoea by 3 days (RR=0.66 95% CI=0.55-0.77, p=0.2). The mean duration of the diarrhoea was reduced by 30.48 hours (p<0.00001).^63,74

The analysis included all cases of infectious diarrhoea from viral diarrhoea to travelers’

diarrhoea. The researchers concluded that probiotics appear to be a useful adjunct to rehydration therapy in treating acute infectious diarrhoea in adults and children.^63,74

All the studies were randomized controlled trials. Methodological quality varied considerably.

Generation of the allocation sequence was adequate in 10 studies, inadequate in 1 study and unclear in 12 studies. Concealment of allocation was adequate in only 9 studies, inadequate in 1 study and unclear in 17 studies. Blinding was adequate in 14 studies, unclear in 6 studies and 3 studies did not use blinding. Loss to follow up was adequate in 14 studies, inadequate in 7 studies and unclear in 2 studies. Mean duration of diarrhoea was reported in 17 studies, all performed in infants and children and was reduced by 29.20 hours in people taking probiotics (95% CI 25.4 to 33.25. fixed effect model: 30.48 hours 95% CI is 18.51 to 42.40, random effects model, chi²=76.51,df-11, p<00001).

The study by Guarino and colleagues demonstrated a particularly dramatic effect with a long mean duration of diarrhoea in the control group. These data was recorded by mothers at home

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rather than by health staff, which may account for the difference. Participants in the probiotic group had an average of 1.51 fewer stools on day 2 of intervention (95% CI 1.17 to 1.85) and 1.31 fewer stools on day 3 (95% CI 1.07 to 1.56) compared to participants in the control group.^63,74 Although the results across studies were not statistically heterogenous, mean stool frequencies on day 2 was reported in only 5 trials and on day 3 in only 4 trials. Adherence to interventions was reported in only a few studies and only 3 studies (Pant, Raza and Shornokova) reported adverse events like vomiting. Only 2 studies by Bhatraga and Raza were done in low income areas (India and Pakistan respectively) where there were high areas of childhood morbidity and mortality. In individual studies, probiotics appeared to be moderately effective as adjunctive therapy in reducing the duration and improving the consistency of diarrhoea stools.

It was noticed that there was insufficient studies of specific probiotic regimens in defined groups of children or adults to inform the development of evidence based treatment guidelines.

This shows that more studies of specific probiotic regimens in well defined patient groups are needed to inform their role in clinical management.

Trials need to use standardized definitions for acute diarrhoea and resolution of the illness and their need to present data separately for important participant subgroups. All studies should include reliable identification of the probiotic being tested and confirm viability and number of organisms for live probiotics.

Researchers should report whether the probiotic prevented or reversed dehydration- the most important complication of acute diarrhoea. In particular, the safety and potential of specific regimens to relieve the risk of persistent diarrhoea and associated malnutrition in children with acute diarrhoea in developing countries merits further study.

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A meta-analysis examining Saccharomyces boulardii for treatment of acute infectious diarrhoea in children combined data from four randomized controlled trials (n=6191). The researchers concluded S boulardii significantly reduced the duration of diarrhoea when compared with the control group for a mean difference of -1.1 days (95% CI -1.3 to -0.8).⁷⁷ However a large trial (n=571) comparing several probiotic preparations to oral rehydration solution concluded that Lactobacillus rhamosus GG or a combination of Lactobacillus delbrueckii, subspecie bulgaricus, Sacchromyces thermophilus, Lactobacilli acidophilus and Bifidobacterioum bifidum was more effective than S boulardii or ORT alone in reducing the duration and severity of acute diarrhoea in children.⁷⁸

Probiotics have also been proven to prevent infectious diarrhoea in healthy children and adults.

Administration of L rhamnosus GG or a placebo to 204 malnourished children in Peru (6-24 months) was administered with a significantly lower incidence of diarrhoea in the treated compared with the placebo group (5.2 vs 6.0 episodes per child per year).⁷⁹ This study was a single blind randomized controlled study and was done in a third world country with low income and areas of poor hygiene.

In a prospective, randomized controlled French study, 287 children (18.9+/- 6months) in day care centres were administered daily either unfermented jellied milk, conventional yoghurt or a probiotic yoghurt product containing L casei species. Each product was given over 1 month.

The conventional yoghurt brought the mean duration of diarrhoea from 8 days down to 5 days and the probiotic drink brought it down to 4.3 days (p<0.01); the incidence of diarrhoea was not different between groups. This study was then later expanded to a randomized controlled multicentre clinical trial in a total of 928 children (6-24 months). During administration of L casei containing fermented milk (daily for 2 months); a lower frequency of diarrhoea was observed compared with the administration of conventional yoghurt (15.9 vs 27%); p<0.05).⁷⁹

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This study was done in an area not representative of low income areas and malnourished children.

The Yakult central institute for microbiological research funded a study in an urban slum community which was conducted by the Kolkata based National Institute of Cholera and Enteric Diseases. The trial was community based randomized double blind and placebo controlled involving 3,758 children aged 1-5 years. About 608 subjects in the study group consumed the company’s probiotic drink every day for 12 weeks and the control group received a placebo. The children were followed up for further 12 weeks. At the end of the 24 week study period, the probiotic group showed reduced occurrence of acute diarrrhoea. The level of protective efficacy for the group was 14% but the authors warned that there was insufficient data for extrapolation of these results for global recommendation. It was noticed that the probiotics shortened the duration of diarhoea by half a day and the incidence of diarrhoea in a community went down by 15% if people had probiotics daily.⁸⁰ In this study, the effects of providing clean drinking water was not considered as a control. If they had been provided clean drinking water, it would have had significant effects reducing the symptoms of diarrhoea too.¹⁸ Another study done in Bolivia; a third world country tried to show the effects of probiotics in children with diarrhoea from rotavirus infection. The study was a randomized double-blind controlled trial in children who were hospitalized in the paediatric centre Albina, Cochabamba.

The children aged 1-23 months were randomly assigned to receive one of 3 treatments: ORS + placebo, ORS + Saccharomyces boulardii or ORS + a compound containing Lactobacillus acidophilus, Lactobacillus rhamnosus, Bifidobacterioum longum and Sacchromyces Boulardii.

The sample size was 20 per group and the median duration of diarrhoea in those that received single probiotics (58 hours) was shorter than in the control group (84.5 hours) (p<0.04). The single probiotic had a higher concentration of bacteria despite having only one species and it yielded better results than in the combination group.⁸¹ The drawback of this study was that the

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authors used lower doses in the combination group that were well below the amount described as ineffective.

From Table 2.1 it is evident that most infectious causes of diarrhoea also produce symptoms like fever, abdominal pain and vomiting. There are few studies showing the effects of probiotics in alleviation of these symptoms. The Bolivian study above showed that there was a shorter duration of fever in children who received the single probiotic as compared to the controls (18 vs 72 hours) (p=0.0042) and the reduction of the duration of vomiting in children who received the mixed probiotics when compared to the controls (0 vs 42.5 hours) (p=0.041).⁸¹

Canani and colleagues in their randomized controlled trials did not discover any significant effect on secondary outcomes such as fever and vomiting due to the low incidence of these symptoms at the time the patients presented but showed significant reduction in the duration of diarrhoea and improvement in the consistency of the stools.⁸²

Three randomized controlled studies tried to compare the effects of probiotics and placebo in reducing vomiting. Pant and colleagues in their trial reported that one out of nineteen children in the control group vomited one dose of the medication but no vomiting occurred in the 20 children in the probiotic group.^63,74 Raza reported that the frequency of vomiting on the second day of intervention was statistically significantly less in children in the probiotic group than in the placebo group.^63,74

Shornikova reported that fewer children in the probiotic group than the placebo group had vomiting from the second day of treatment and this was statistically significant on days 2 and 4. No child in the probiotic group vomited after the 3^rd day of treatment whereas vomiting persisted to the 6^th day in 2 out of 21 children in the placebo group.^63,74

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Few studies have tried to study the effects of probiotics on fever. The available studies worked on the effects of probiotics on hay fever and other allergic conditions. Very few had worked on fever and diarrhoea. Leyer and colleagues in their randomized double blind controlled trial to study the effects of probiotics on cold and influenza like symptoms incidence and duration in children discovered that probiotics ( Lactobacillus acidophilus alone or in combination with Bifidobacterium animalis) reduced fever incidence by 53% (p=0.0085) and 72.7% (p=0.0001) in the single and combination probiotics respectively. Fever, cough and rhinorrhoea duration decreased significantly relative to placebo by 32% (single strain; p=0.0023) and 48% (strain combination; (p<0.001).⁸³

The Yakult study in 2011 noticed that milk fermented with Lactobacillus casei may help to alleviate fever caused by norovirus gastroenteritis by correcting imbalances of intestinal microflora. The researchers stated that the continuous intake of the L casei fermented milk did not prevent infectious gastroenteritis caused by the norovirus and also did not alleviate the infection because there was no significant improvement in the diarrhoea and vomiting associated with the infection.⁸⁴ The drawback of this study was that it was done on elderly frail care home residents in Japan which was not reflective of low income countries and malnourished children.

Abdominal pain is another symptom commonly associated with diarrhoea. Few studies have tried to study the effects of probiotics in patients with abdominal pain and diarrhoea in children.

It’s possible that one reason is that most children are very young and cannot report the symptoms of pain. Doctor Francavilla Ruggiero of the University of Bari in Italy tried to see the effects of probiotics on chronic abdominal pain in children. He stated that about 10 to 15%

of school children suffer from recurrent abdominal pain. Yet little evidence exists to date for helpful medications or dietary changes. Francavilla and his team researched on Lactobacillus GG in the paediatric population for this problem since there was evidence of probiotics in the

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management of irritable bowel syndrome. At the end of the study the probiotics significantly reduced the frequency and intensity of the abdominal pains (p<0.01). The frequencies of the abdominal pain fell from 4 episodes per week to 1 per week for the probiotic group and 2 per week for those on placebo.⁸⁵ This study was conducted in children in a wide range of communities in southern Italy which was not representative of other parts of the world like third world countries. He also stated that no other strain of probiotics is a valid alternative for this condition. He noted that probiotics are not all the same and should not be used deliberately for all the possible indications.⁸⁵ This supports the fact that we are entering the era of targeted probiotic use. The study also showed that to fully achieve the benefit of the probiotic on abdominal pain, one has to take it for a long period of time of at least 8 weeks.⁸⁵

No study could be found that tried to evaluate the effects of probiotics on weight loss in children that had diarrhoea but Mohammed Al-Hosni and colleagues in a randomized controlled double blind study discovered that infants who had extremely low birth weight (ELBW) and were fed Lactobacillus rhamnosus and Bifidobacterium infantis once daily for 34 weeks had superior weight gain even though the average daily volume of their feeding was less than in the control group. There were no statistically significant differences in other complications of prematurity such as sepsis or necrotizing enterocolitis. This suggests that probiotic supplementation plays a major role in feeding tolerance and nutrient absorption.⁸⁶ This study was done in 3 medical centres in Canada and hence not reflective of a third world population.

Jean piere Chouraqui and colleagues did not find any statistically significant weight gain between infants fed with probiotics (L rhamnosus GG) and the control group.⁸⁷

Other useful benefits of probiotics include managing lactose intolerance,⁶³ prevention of colon cancer,⁸⁸ lowering cholesterol,⁸⁹ lowering high blood pressure,⁸⁹ improving immune function

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and preventing infections.⁸⁹ It is also useful in treating Helicobacter pylori infections^90,91 and treatment of irritable bowel syndrome and colitis.⁹²