Maija Saxelin

Demonstration of safety of probiotics: a review.

Probiotics are commonly defined as viable microorganisms (bacteria or yeasts) that exhibit a beneficial effect on the health of the host when they are ingested. They are used in foods, especially in fermented dairy products, but also in pharmaceutical preparations. The development of new probiotic strains aims at more active beneficial organisms. In the case of novel microorganisms and modified organisms the question of their safety and the risk to benefit ratio have to be assessed. Lactic acid bacteria (LAB) in foods have a long history of safe use. Members of the genera Lactococcus and Lactobacillus are most commonly given generally-recognised-as-safe (GRAS) status whilst members of the genera Streptococcus and Enterococcus and some other genera of LAB contain some opportunistic pathogens. Lactic acid bacteria are intrinsically resistant to many antibiotics. In many cases resistances are not, however, transmissible, and the species are also sensitive to many clinically used antibiotics even in the case of a lactic acid bacteria- associated opportunistic infection. Therefore no particular safety concern is associated with intrinsic type of resistance. Plasmid-associated antibiotic resistance, which occasionally occurs, is another matter because of the possibility of the resistance spreading to other, more harmful species and genera. The transmissible enterococcal resistance against glycopeptide antibiotics (vancomycin and teicoplanin) is particularly noteworthy, as vancomycin is one of the last effective antibiotics left in the treatment of certain multidrug-resistant pathogens. New species and more specific strains of probiotic bacteria are constantly identified. Prior to incorporating new strains into products their efficacy should be carefully assessed, and a case by case evaluation as to whether they share the safety status of traditional food-grade organisms should be made. The current documentation of adverse effects in the literature is reviewed. Future recommendations for the safety of already existing and new probiotics will be given.

Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial

Abstract Objective: To examine whether long term consumption of a probiotic milk could reduce gastrointestinal and respiratory infections in children in day care centres. Design: Randomised, double blind, placebo controlled study over seven months. Setting: 18 day care centres in Helsinki, Finland. Participants: 571 healthy children aged 1-6 years: 282 (mean (SD) age 4.6 (1.5) years) in the intervention group and 289 (mean (SD) age 4.4 (1.5) years) in the control group. Intervention: Milk with or without Lactobacillus GG. Average daily consumption of milk in both groups was 260 ml. Main outcome measures: Number of days with respiratory and gastrointestinal symptoms, absences from day care because of illness, respiratory tract infections diagnosed by a doctor, and course of antibiotics. Results: Children in the Lactobacillus group had fewer days of absence from day care because of illness (4.9 (95% confidence interval 4.4 to 5.5) v 5.8 (5.3 to 6.4) days, 16% difference, P=0.03; age adjusted 5.1 (4.6 to 5.6) v 5.7 (5.2 to 6.3) days, 11% difference, P=0.09). There was also a relative reduction of 17% in the number of children suffering from respiratory infections with complications and lower respiratory tract infections (unadjusted absolute % reduction −8.6 (−17.2 to −0.1), P=0.05; age adjusted odds ratio 0.75 (0.52 to 1.09), P=0.13) and a 19% relative reduction in antibiotic treatments for respiratory infection (unadjusted absolute % reduction −9.6 (−18.2 to −1.0), P=0.03; adjusted odds ratio 0.72 (0.50 to 1.03), P=0.08) in the Lactobacillus group. Conclusions: Lactobacillus GG may reduce respiratory infections and their severity among children in day care. The effects of the probiotic Lactobacillus GG were modest but consistently in the same direction. What is already known on this topic Children attending day care centres are at high risk of respiratory and gastrointestinal infection The successful prevention of respiratory infections could be extremely useful for families and for society in general Short term use of probiotic bacteria has been shown to reduce the severity of rotavirus diarrhoea and the incidence of diarrhoea associated with the use of antibiotics What this study adds In a double blind, randomised, long term study milk containing Lactobacillus GG slightly reduced the incidence of respiratory infections and antibiotic treatment in children

Lactic acid bacteria in the treatment of acute rotavirus gastroenteritis

We compared different lactic acid bacteria for their effect on the immune response to rotavirus in children with acute rotavirus gastroenteritis. After initial oral rehydration, 49 children aged 6 to 35 months with rotavirus gastroenteritis randomly received cither Lactobacillus casei subsp. casei strain GG (LGG), L. casei subsp. rhamnosus (Lactophilus), or a combination of Streptococcus thermophilus and L. delbriickii subsp. bulgaricus (Yalacta) twice daily for 5 days. Serum antibodies to rotavirus, total number of immunoglobulin-secrcting cells (ISC), and specific antibody-secreting cells (sASC) to rotavirus were measured at the acute stage and at convalescence. The mean (SD) duration of diarrhea was 1.8 (0.8) days in children who received LGG, 2.8 (1.2) days in those receiving Lactophilus, and 2.6 (1.4) days in those receiving Yalacta (F = 3.3, p = 0.04). The ISC response was comparable in the three study groups, but the rotavirus-specific immune responses were different. LGG therapy was associated with an enhancement of IgA sASC to rotavirus and serum IgA antibody level at convalescent stage. We conclude that certain strains of lactic acid bacteria, particularly LGG, promote serum and intestinal immune responses to rotavirus, and thus may be important in establishing immunity against rotavirus reinfections

Comparative genomic analysis of Lactobacillus rhamnosus GG reveals pili containing a human- mucus binding protein

To unravel the biological function of the widely used probiotic bacterium Lactobacillus rhamnosus GG, we compared its 3.0-Mbp genome sequence with the similarly sized genome of L. rhamnosus LC705, an adjunct starter culture exhibiting reduced binding to mucus. Both genomes demonstrated high sequence identity and synteny. However, for both strains, genomic islands, 5 in GG and 4 in LC705, punctuated the colinearity. A significant number of strain-specific genes were predicted in these islands (80 in GG and 72 in LC705). The GG-specific islands included genes coding for bacteriophage components, sugar metabolism and transport, and exopolysaccharide biosynthesis. One island only found in L. rhamnosus GG contained genes for 3 secreted LPXTG-like pilins (spaCBA) and a pilin-dedicated sortase. Using anti-SpaC antibodies, the physical presence of cell wall-bound pili was confirmed by immunoblotting. Immunogold electron microscopy showed that the SpaC pilin is located at the pilus tip but also sporadically throughout the structure. Moreover, the adherence of strain GG to human intestinal mucus was blocked by SpaC antiserum and abolished in a mutant carrying an inactivated spaC gene. Similarly, binding to mucus was demonstrated for the purified SpaC protein. We conclude that the presence of SpaC is essential for the mucus interaction of L. rhamnosus GG and likely explains its ability to persist in the human intestinal tract longer than LC705 during an intervention trial. The presence of mucus-binding pili on the surface of a nonpathogenic Gram-positive bacterial strain reveals a previously undescribed mechanism for the interaction of selected probiotic lactobacilli with host tissues.

Effect of Long–Term Consumption of a Probiotic Bacterium, Lactobacillus rhamnosus GG, in Milk on Dental Caries and Caries Risk in Children

Lactobacillus rhamnosus GG, ATCC (LGG), has shown antagonism to many bacteria including mutans streptococci. This randomized, double–blind, placebo–controlled intervention study was designed to examine whether milk containing LGG has an effect on caries and the risk of caries in children when compared with normal milk. 594 children, 1–6 years old, from 18 municipal day–care centres were included. The children received the milk with meals from coded containers 5 days a week in the day–care centres for 7 months. The children’s oral health was recorded at baseline and at the end, using WHO criteria. The caries risk was calculated based on clinical and microbiological data, comprising mutans streptococcus levels from dental plaque and saliva. The risk was classified as high if the child had a dmft/DMFT or initial caries score >0, and a mutans streptococcus count ≧105 CFU/ml. The results showed less dental caries in the LGG group and lower mutans streptococcus counts at the end of the study. LGG was found to reduce the risk of caries significantly (OR = 0.56, p = 0.01; controlled for age and gender, OR = 0.51, p = 0.004). The effect was particularly clear in the 3– to 4–year–olds. Thus, milk containing the probiotic LGG bacteria may have beneficial effects on children’s dental health.

Promotion of IgA Immune Response in Patients with Crohn’s Disease by Oral Bacteriotherapy with Lactobacillus GG

The effect of oral bacteriotherapy with human Lactobacillus casei strain GG (10(10) colony-forming units twice daily for 10 days) was investigated in Crohns disease and in juvenile chronic arthritis which are chronic inflammatory diseases associated with impaired mucosal barrier function. During oral bacteriotherapy, the gut immune response was indirectly assessed by solid-phase enzyme-linked immunoassay in 14 children with Crohns disease, in 9 with juvenile chronic arthritis, and in 7 controls. The immunostimulatory effect of Lactobacillus GG was specific for Crohns disease, irrespective of its activity: the mean (95% confidence interval) number of specific antibody secreting cells in the IgA class to beta-lactoglobulin increased significantly from 0.2 (0.04-1.3) to 1.4 (0.3-6.0)/10(6) cells and to casein from 0.3 (0.1-1.4) to 1.0 (0.2-4.8)/10(6) cells. The results indicate that orally administered Lactobacillus GG has the potential to increase the gut IgA immune response and thereby to promote the gut immunological barrier. Consequently, Lactobacillus GG could provide an adjunct nutritional therapy for Crohns disease.

Lactobacillus Bacteremia during a Rapid Increase in Probiotic Use of Lactobacillus rhamnosus GG in Finland

Lactobacilli supposedly have low pathogenicity; they are seldom detected in blood culture. Lactobacillus rhamnosus GG, which originates indigenously in the human intestine, became available for use as a probiotic in 1990 in Finland. We evaluated the possible effects of the increased probiotic use of L. rhamnosus GG on the occurrence of bacteremia due to lactobacilli. Lactobacilli were isolated in 0.02% of all blood cultures and 0.2% of all blood cultures with positive results in Helsinki University Central Hospital and in Finland as a whole, and no trends were seen that suggested an increase in Lactobacillus bacteremia. The average incidence was 0.3 cases/100,000 inhabitants/year in 1995-2000 in Finland. Identification to the species level was done for 66 cases of Lactobacillus bacteremia, and 48 isolates were confirmed to be Lactobacillus strains. Twenty-six of these strains were L. rhamnosus, and 11 isolates were identical to L. rhamnosus GG. The results indicate that increased probiotic use of L. rhamnosus GG has not led to an increase in Lactobacillus bacteremia.

Lactobacillus Bacteremia, Clinical Significance, and Patient Outcome, with Special Focus on Probiotic L. Rhamnosus GG

Lactobacillus bacteremia is a rare entity, and its clinical significance is poorly defined. We have reviewed the risk factors and outcome for 89 case patients with Lactobacillus bacteremia. Species characterization was done in 53% of the cases, revealing 25 L. rhamnosus strains and 22 other Lactobacillus species. In 11 cases, the strain was identical with the probiotic L. rhamnosus GG. In 82% of the cases, the patients had severe or fatal comorbidities. Predisposing factors to bacteremia were immunosuppression, prior prolonged hospitalization, and prior surgical interventions. No significant differences were observed in these predisposing factors or clinical features between patients with cases associated with the various Lactobacillus species, other than higher C-reactive protein values in patients with L. rhamnosus bacteremia. Mortality was 26% at 1 month and was 48% at 1 year. In multivariate analysis, severe underlying diseases were a significant predictor for mortality (odds ratio [OR], 15.8), whereas treatment with antimicrobials effective in vitro was associated with lower mortality (OR, 0.22). We conclude that lactobacilli in blood cultures are of clinical significance and that their susceptibility should guide decisions about antimicrobial treatment.

Suppression of lymphocyte proliferation in vitro by bovine caseins hydrolyzed with Lactobacillus casei GG–derived enzymes

BACKGROUNDnProcessing of proteins in the gut and activation of T-cell suppression leads to systemic hyporesponsiveness to ingested protein antigens.nnnOBJECTIVEnThe study was designed to determine whether lactobacilli, a major part of human intestinal microflora, can contribute to degradation of food antigens in the gut and modify their immunoactivities.nnnMETHODSnLymphocyte transformation tests were carried out in healthy adults to determine the mitogen-induced lymphocyte proliferative responses to bovine caseins hydrolyzed with pepsin and trypsin and to bovine caseins additionally hydrolyzed with enzymes derived from Lactobacillus casei strain GG (ATCC 53103).nnnRESULTSnIn experiments done with caseins hydrolyzed with pepsin and trypsin, beta- and alpha(s1)-caseins significantly suppressed the proliferation of lymphocytes at 0.1 and 10 micrograms/ml, respectively, when compared with corresponding control cultures without these hydrolysates. In contrast, kappa-casein significantly stimulated the proliferation of lymphocytes at 10 micrograms/ml. In experiments done with caseins additionally hydrolyzed with L. casei GG-derived enzymes, there was one consistent effect on lymphocyte proliferation: suppression by alpha(sl)-, beta-, and kappa-caseins at 0.1, 10, and 1000 micrograms/ml, respectively.nnnCONCLUSIONSnHydrolysis of caseins with L. casei GG-derived enzymes generates molecules with suppressive effects on lymphocyte proliferation. In addition, intestinal bacteria can be beneficial in the downregulation of hypersensitivity reactions to ingested proteins in patients with food allergy.

Lactobacillus GG—a human probiotic strain with thorough clinical documentation

Abstract Probiotic bacteria for human nutrition are generally strains of lactic acid bacteria or bifidobacteria. The beneficial effects of these strains on human health and well‐being are documented in experimental and clinical studies. Lactobacillus (casei subsp.) rhamnosus GG (ATCC 53103) is a probiotic strain of human origin. The strain has most of the characteristics generally proposed for a good probiotic strain, including excellent survival in the stomach and small intestine and transient colonization of the gastrointestinal tract, which is based on its adhesion capacity to intestinal cells. Successful recovery of the strain in stool samples has made dose‐response studies possible and enabled the evaluation of effective dosing using food products. The beneficial effects of the strain have been shown in many types of intestinal disturbances caused by pathogenic bacteria and viruses, as well as in prophylactic use. The latest studies on Lactobacillus GG have shown stabilizing effect on gut permeabilit...