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Will probiotics be banned for the severely immunocompromised?

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W IL L P R O B IO T IC S BE B A N N ED FOR T H E SE VE R E LY IM M U N O C O M P R O M IS E D ?

Piotr Kochan*’b, Magdalena Struś', Piotr B. Heczkoab

3rd International Probiotic Conference 2008 (IPC2008): Probiotics for the 3rd Millennium, 4-7 June 2008, High Tatras, Slovakia

According to the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) definition, probiotics are live microorganisms, which when administered in adequate amount confer a health benefit on the host. The Polish Society for Probiotics and Prebiotics is strongly advocating this definition and the safety aspects that FAO/WHO stress.

The fact that many beneficial microorganisms have a long history of safe use in a large population and are generally considered as safe, as well as that most studies do not show any adverse events related to probiotics may have been shaken by some recently available data, primarily owing to the publicity related to PROPATRIA (PRObiotics in PAncreatitis TRIAI) study in the Netherlands. The statement released by the International Scientific Association for Probiotics and Prebiotics following the results of this Dutch study lists some very important conclusions, questions some aspects of study and calls to the scientific community to use the term probiotic only if appropriate criteria are met, but probably one single point from these conclusions will be vital for future clinical trials on probiotics, i.e. establishment of safety of the approach when treating vulnerable patients, especially research to define proper animal models of safety. The table below lists some recent studies described in the literature and their outcomes:

Table 1. Recently published studies on microbes with clinical applications and their unexpected outcomes.

Published study Patient groups Condition Strains & doses Results Conclusions

Probiotic prophylaxis in predicted severe acute pancreatitis:

a randomised, double-blind, placebo-controlled trial

Lancet 2008;371:651-9.

Probiotics group n=152 and

placebo group n=144

acute pancreatitis

Ecologic 641 (Lactobacillus acidophilus, L casei, L. salivarius, Lactococcus lactis, Bifidobacterium bifidum, and B. lactis).

Total daily dose of 1010 bacteria given via nasojejunal tube.

Infectious complications: 46 in probiotics group vs. 41 control (none by administered strains).

Bowel ischaemia: 9 in probiotics group vs. 0 control.

Deaths: 24 in probiotics group vs. 9 control.

Speculated m echanism o f bowel ischaemia:

increased local oxygen dem and to alrea dy critically reduced blood flo w or local inflam m ation at the m ucosal level?

“ ...probiotic prophyla xis w ith th is com bin atio n o f probiotic strains did not reduce th e risk o f infectious com plications and w as associated with an increased risk o f mortality. P robiotic prophyla xis should th erefore n o t be adm in istered in this category o f patients."

Randomized, double-blind, placebo-controlled trial of probiotics for primary prevention: no clinical effects of Lactobacillus GG supplementation Pediatrics 2008; 121 :e850-6.

Probiotics group n=50 and

placebo group n=44

atopic dermatitis

Atopic dermatitis: 14 in probiotic Lactobacillus GG (American group vs. 12 control Type Culture Collection 53103). (comparable severity).

5x10® colony-forming units twice Recurrent episodes of wheezing daily p e r os. bronchitis: 13 in probiotics group

vs. 4 control.

"S upplem entation w ith Lacto ba cillu s GG durin g pregnancy and early infa ncy neither reduced the incidence o f atop ic derm atitis nor altered the severity o f a to p ic derm atitis in affected children but w as associated w ith an increased rate o f recu rren t episodes o f w heezing bronchitis. Therefore, Lacto ba cillu s GG can no t be ge ne rally recomm ended fo r prim ary prevention."

Probiotic supplementation for the first 6 months of life fails to reduce the risk of atopic dermatitis and increases the risk of allergen sensitization in high-risk children:

a randomized controlled trial J Ailergy Clin Immunol 2007;

119:184-91.

Probiotics group n=89 and

placebo group n=89

atopic dermatitis

Lactobacillus acidophilus LAVRI-A1.

3x109 L. acidophilus LAVRI-A1 daily p e r os.

Atopic dermatitis: 23 in probiotic group vs. 20 control (comparable severity).

At 12 months, the rate of sensitization was significantly higher in the probiotic group (p =0.030).

“Early probiotic supplem entation with L acid op hilus did not reduce the risk o f AD in high-risk infants and w as associated w ith increased allergen sensitization in infants receiving supplements. T he long-term significance o f the increased rate of sensitization needs to be investigated in fu rthe r studies. T he se find ing s cha llen ge th e role o f probiotics in alle rg y prevention.”

Discussion: There are documented situations in the literature when the use of microbial products has resulted in unexpected outcomes, contrary to what the authors have actually hypothesized. There are also reports in the literature of infections caused by genera that are usually considered beneficial. Moreover, only little is known about the immunological mechanisms of action of probiotics and their effects are probably strain-specific. Experts agree that probiotics are used on a very large scale and basically show no adverse events, but looking further, not many probiotic strains have documented randomized, double blind, placebo-controlled trials on large populations showing their safety in special situations, e.g. in chronically ill or severely immunocompromised subjects. The studies described show different dosages as well as modes of administration, that may play a role in the hypothetical "overdosing” of the bacteria and have an indirect influence on adverse events (and not being the isolated agent of infection).

Conclusions: Does the future hold any more surprises and will we see labels on probiotics stating: „ATTENTION! Not to be used in the severely ill or immunocompromised"? Can probiotic use show any adverse events at all? And will we see the origin of a somewhat controversial, rare condition, namely “probiotic infection”?

Two action items that we should definitely consider in the near future that will improve safety, are:

. Investigation and definition of proper animal safety models, that will enable

. Performance of safety trials on defined animal models, before investigating probiotics in a preferably large, multicentre, double-blind randomized placebo-controlled trial settings.

Possible reasons fo r translocation

& septic morbidity:

- severe inflammation - bowel ischaemia - increased gut

permeability

- bacterial overgrowth - gut wall

necrosis - im mune system

compromise

Figure 1. Probable pathway from gut through sepsis to multiple organ dysfunction syndrome and death.

* Department of Bacteriology, Microbial Ecology and Parasitology, C h a iro f Microbiology, Jagiellonian University Medical College, 18 Czysta Street, 31-121 Cracow, Poland

b Polish Society for Probiotics and Prebiotics, 18 Czysta Street, 31-121 Cracow, Poland

References available by request from Piotr Kochan, M.D.

E-mail: pkochan@cm-uj.krakow.pl Telephone: +4812 633 25 67 Fax: +4812 423 39 24

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