Bifidobacteria (Bifidobacterium spp.)
1. Identity: Taxonomy, Nomenclature, and Natural Sources
1.1 Scientific Classification
Bifidobacterium is the genus name for a group of anaerobic, Gram-positive, saccharoclastic bacteria that constitute one of the most studied probiotic genera in microbiology and nutrition science. Bifidobacteria belong to the phylum Actinobacteria, whereas other lactic acid bacteria such as Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella are Firmicutes. Bifidobacteria are heterofermentative anaerobic, Gram-positive bacteria belonging to the class Actinobacteria, containing genomes with a high G+C content.
They are non-spore-forming, non-motile, branched (usually Y-shaped) anaerobic bacteria that inhabit the mouth, guts, and vaginas of animals, including humans. They mainly colonize the intestines of humans, other mammals, and insects, and some bifidobacteria have also been isolated from environmental sources such as sewage.
The bifidobacterial species validly identified by 2016 totaled 54, with 9 subspecies. The genus continues to expand as genomic methods reveal new members. The most clinically and commercially relevant species include B. longum, B. bifidum, B. breve, B. infantis (reclassified as B. longum subsp. infantis), B. animalis subsp. lactis, B. adolescentis, and B. pseudocatenulatum.
1.2 Defining Biochemical Marker: The Bifid Shunt
Bifidobacteria catabolize hexoses through a peculiar metabolic pathway involving the key enzyme fructose-6-phosphoketolase (EC 4.1.2.2), known as the fructose-6-phosphate pathway or the so-called bifid shunt. Before the reclassification of certain Bifidobacterium species into new genera, this enzyme was considered a taxonomic character for identification at the genus level, but it is now considered a taxonomic marker for the family Bifidobacteriaceae.
1.3 Natural Sources
Bifidobacteria are naturally found in multiple ecological niches. Bifidobacteria are primarily found in the gastrointestinal tracts of mammals, with certain strains being host-specific. In humans, they are most abundant in infants, particularly those who are breastfed, due to their ability to digest human milk oligosaccharides (HMOs), and are naturally present in healthy adults' colon and large intestine, though in lower abundance than in infants. They are present in traditional fermented foods such as some yogurts and cultured dairy products, and are also detected in fermented vegetables, infant formulas, and probiotic supplements.
1.4 Common Commercial Forms and Preparations
Origin and production of commercial bifidobacterial preparations involve isolation historically from human or animal intestinal microbiota and dairy fermentations; commercial manufacture uses pure-culture fermentation, cell harvest, cryoprotectants, lyophilization or spray drying, and quality control covering strain identity, purity, and CFU stability. Commercially, Bifidobacterium is made available as:
- Encapsulated powders (lyophilized / freeze-dried) — the most common supplement format, providing measured CFU counts per dose
- Fermented dairy products — yogurts, kefirs, and bifidus milks in which live cultures are added as starter or adjunct cultures
- Sachets and powders — commonly used in infant and pediatric formulations
- Synbiotic preparations — combination products pairing Bifidobacterium strains with prebiotic substrates (e.g., fructo-oligosaccharides, galacto-oligosaccharides)
- Heat-inactivated (postbiotic) forms — such as heat-inactivated B. bifidum MIMBb75, evaluated in clinical trials for IBS
Popular delivery systems for bifidobacteria include freshly fermented or unfermented dairy foods, including milk, yoghurt, ice cream, desserts, cheese, and beverages.
2. Historical and Traditional Use
2.1 Antiquity: Fermented Milk Across Cultures
Although the bacteria themselves were not identified until modern times, the foods in which they thrive have a recorded history of therapeutic use. Fermented milks have been used as a health-promoting food even before the discovery of microorganisms and lactic acid bacteria, and written records of using fermented milk for various gastrointestinal infections go back to 76 B.C. Probiotics have been recognized since the Roman and Greek eras; the Roman naturalist Pliny recommended the consumption of fermented milk for intestinal problems.
Since ancient times, fermented foods such as yogurt, kefir, beer, and wine have been used to promote health in many cultures including Egypt, Rome, and the Middle East.
2.2 Scientific Discovery: Henri Tissier (1899–1906)
In 1899, Henri Tissier, a paediatrician from the Institut Pasteur, discovered Bifidobacterium bifidum in faecal samples of breast-fed infants and reported that the bacteria could be used to help prevent babies from developing diarrheal illness. Henry Tissier first observed and documented that children with diarrhea had low bifidobacterial counts in the gut, whereas these bacteria were abundant in healthy children. He proposed that supplementation could restore gut flora in diarrheal patients — an idea that anticipated the modern probiotic concept.
2.3 Early 20th Century: Metchnikoff and the Probiotic Hypothesis
In 1905, Élie Metchnikoff observed that Bulgarians lived longer thanks to fermented milk, initiating the idea of "beneficial bacteria" and proposing the use of lactic acid bacteria to prolong life and reduce the negative effects of abnormal gut microbiota. Although there were earlier reports of fermented milks with implied health benefits, Metchnikoff was the first to put the subject on a scientific basis, speaking and publishing on his theories of sound health and longevity from the ingestion of lactobacilli and other bacteria present in such foods as yogurt, kefir, and sour milk.
2.4 Mid-20th Century to Modern Era
In the US before the 1980s, the use of bifidobacteria in foods was limited to a few products intended for therapeutic treatment; among the earliest products was a bifidus milk developed by Mayer in the 1940s for use in the treatment of infants afflicted with nutritional deficiencies. By the 1960s, enough evidence had accumulated to show it was possible to modify intestinal biota with B. bifidum, and in the 1970s, Japan produced its first bifidus product, a fermented milk containing B. longum and Streptococcus thermophilus in 1971, with bifidus yoghurt following in 1979.
During the 1960s–1990s, taxonomic refinements identified B. animalis and later subspecies distinctions as dairy strains became widely used; from the 1990s onward, strain banking and clinical trials expanded, with the 2010s–2020s bringing expanded RCTs for constipation, antibiotic-associated diarrhea, and immune endpoints, along with regulatory clearances (GRAS/QPS) for specified strains.
3. Key Constituents and Mechanisms of Action
3.1 Structural and Metabolic Components
The probiotic effects of Bifidobacterium are thought to be multifactorial, arising from structural surface components, secreted metabolites, and indirect ecological effects on the broader gut microbiome. While there has been a large volume of literature characterizing the probiotic properties of various bifidobacterial species, the likely multifactorial mechanisms underlying these effects remain elusive; however, recent work has shed light on Bifidobacterium surface structural polysaccharide and protein elements, as well as its metabolic products, as commensal mediators of immune homeostasis.
3.2 Short-Chain Fatty Acid Production
A primary mechanism through which bifidobacteria exert their effects is the fermentation of dietary carbohydrates — including non-digestible oligosaccharides and human milk oligosaccharides — into short-chain fatty acids (SCFAs). SCFAs, mainly butyrate, acetate, and propionate, play several key roles in human health, from the modulation of the immune system to the regulation of metabolic pathways and the restoration of the gut barrier.
Butyrate serves as an essential energy source for colonocytes, strengthening epithelial integrity, actively modulating local and systemic immune functions, suppressing the expression of pro-inflammatory cytokines, and enhancing mucosal defense mechanisms. Beyond barrier function, butyrate exhibits strong anti-inflammatory properties by a variety of mechanisms, including histone deacetylase (HDAC) inhibition, immune cell activity modulation, and a reduction in the production of pro-inflammatory cytokines.
Notably, bifidobacteria are not only direct producers of SCFAs but also enable other SCFA-producing organisms. In co-culture studies, Bifidobacterium is necessary for either the establishment of a butyrate producer or for enhancing butyrate production through the metabolism of human milk oligosaccharides. This butyrogenic effect results from cross-feeding interaction between bifidobacteria and Clostridiales, which negatively correlates with inflammatory bowel disorders.
3.3 Immune Modulation
Depletion or absence of Bifidobacterium in humans and model organisms is associated with autoimmune responses and impaired immune homeostasis. At the cellular level, Bifidobacterium upregulates suppressive regulatory T cells (Tregs), maintains intestinal barrier function, modulates dendritic cell and macrophage activity, and dampens intestinal Th2 and Th17 programs.
Butyrate and niacin suppress colonic inflammation and carcinogenesis through activation of Gpr109a, stimulating dendritic cells and macrophages to produce IL-10, leading to enhanced differentiation of Tregs; furthermore, co-culture of certain bifidobacterial strains results in the reduction of pro-inflammatory cytokines produced by human colorectal adenocarcinoma cells and decreased IL-8 in the colons of colitic mouse models.
3.4 Human Milk Oligosaccharide (HMO) Metabolism
As the sole nutrition provided to infants, bioactive molecules dissolved in milk influence the development of gut microbiota; human milk oligosaccharides (HMOs) are minimally digested by the infant and persist to negatively and positively regulate gut microbiota, and infant-type bifidobacteria utilize these soluble carbohydrate oligomers by convergent mechanisms. Bifidobacterium longum subsp. infantis efficiently consumes several small-mass HMOs and possesses a large gene cluster and other loci dedicated to HMO metabolism.
3.5 Gut Barrier Integrity
Evidence suggests that bifidobacteria supplementation, which serves to restore a balanced microbial composition, modulates immune function, gut microbiota, and intestinal mucosal adhesion, with studies demonstrating positive effects on epithelial cell adherence, reinforcement of tight junctions, stimulation of IgA production, and cell-mediated immune responses.
3.6 Neuroactive Metabolite Production (Gut-Brain Axis)
Both Bifidobacterium and Lactobacillus strains have been shown to synthesize GABA, with the administration of GABA-producing strains leading to altered depression-like behaviors in animal models. Supplementation with Bifidobacterium breve and related strains has been shown to increase indole-3-lactic acid (ILA) levels, a metabolite capable of modulating neuroinflammation through aryl hydrocarbon receptor (AhR) signaling; in depressed mice, hippocampal ILA levels were reduced, a deficit reversed by administration of ILA-producing bifidobacteria, with corresponding improvements in depressive-like behaviors.
The regulation of gut microbiota by probiotics can alter brain function through the gut-brain axis and regulate mood; these "psychoprobiotic" bacteria communicate with the brain mainly through the pathway of the vagus nerve, tryptophan metabolites, and microbial products, producing and delivering neuroactive substances that directly or indirectly regulate cognitive and emotional states.
4. Scientific Evidence by Area of Use
4.1 Irritable Bowel Syndrome (IBS)
IBS is among the most extensively studied indications for bifidobacterial supplementation. In IBS, patients typically present with significantly lower levels of bifidobacteria in faecal and duodenal mucosa samples, yet other major bacterial groups remain preserved. A meta-analysis found that bifidobacteria was the only microbiota alteration of specific intestinal microbes in IBS determined by quantitative polymerase chain reaction and bacterial culture.
A 2020 systematic review (Pratt and Campbell, University of Leeds) examined 8 double-blind, placebo-controlled RCTs involving 1,045 adults with Rome-diagnosed IBS. The dose of total bifidobacteria ranged from 106 to >1011 CFU and duration of supplementation ranged between 2 and 8 weeks; bifidobacteria was delivered through fermented milk products, encapsulation, or a malted milk beverage. From the studies included, 50% (n=4) found a statistically significant improvement in abdominal pain following supplementation compared to placebo, 38% (n=3) found non-significant improvements, and 12% (n=1) showed a statistically significant dose-response effect.
A specific strain — Bifidobacterium longum 35624 — has received more focused attention. A randomized placebo-controlled trial by Whorwell et al. (2006) in 362 women with IBS showed a significant reduction in abdominal pain/discomfort on a 6-point Likert scale by week 4 of treatment with B. longum 35624 at 1 × 108 CFU compared with the placebo group (p = 0.023); the other two probiotic doses tested (1 × 106 and 1 × 1010 CFU) were not significantly effective. Heat-inactivated forms have also been trialed: an 8-week oral daily administration of heat-inactivated B. bifidum MIMBb75 showed improvement in abdominal pain of 34% in the treatment group compared to 19% in the placebo group.
Evidence strength: A meta-analysis did not show the efficacy of the isolated use of Bifidobacterium; the evidence of an association between supplementation with Bifidobacterium and symptomatic control in patients with IBS is not clear, though some studies seem to demonstrate benefits in improving symptoms (SORT C — low-certainty evidence). Heterogeneity in strains, doses, and IBS subtypes across trials limits firm conclusions.
4.2 Infant Health: Gut Colonization and Necrotizing Enterocolitis (NEC)
In one-day-old newborns, Enterococcus and Streptococcus were the microorganisms most frequently isolated, while from 10 days until 3 months of age, bifidobacteria became predominant, particularly in breastfed infants. A plethora of studies has provided evidence to support the association of the reduced abundance of infant-type bifidobacterial species with immune disorders in children or adults, such as pathogen infection, necrotizing enterocolitis (NEC), allergy, asthma, atopic dermatitis, type 1 diabetes mellitus, and obesity.
Regarding NEC specifically, in 1999, Hoyos found that the oral administration of prophylactic B. longum subsp. infantis and Lactobacillus acidophilus at a dose of 2.5 Ă— 108 CFU of each organism for one year decreased the incidence of and mortality due to NEC in 1,237 neonates in an intensive-care unit. Subsequent follow-up studies have found that the relative risk of NEC reduced significantly in infants on probiotic treatment regimens that consisted of infant-type bifidobacteria, although the optimal strains, treatment durations, and dosages have not yet been determined.
At the mechanistic level in animal models, administration of B. infantis significantly reduced the incidence of NEC, decreased expression of Il6, Cxcl1, Tnfa, Il23, and iNOS, and decreased expression of the antimicrobial peptides Reg3b and Reg3g. Probiotics or their secretions protect premature infants against NEC through anti-inflammatory mechanisms; using secretions from B. longum subsp. infantis, fetal enterocyte reduction of IL-6 activation after IL-1β stimulation was shown to be mediated through TLR-4.
Evidence from the B. infantis EVC001 strain supports gut colonization outcomes: within days of supplementation, increases in total bifidobacteria in the feces rose from approximately 20% relative abundance to roughly 80%, an increase driven exclusively by the supplemented B. longum subsp. infantis.
Evidence strength: Evidence for bifidobacteria in reducing NEC is promising but the field lacks fully standardized protocols. Randomized controlled phase 3 trials (e.g., B. breve BBG-001, published in The Lancet, 2016) have been conducted in very preterm infants, though results have been mixed. Animal and mechanistic data are strong; human trial data support benefit but optimal strain, dosing, and patient selection remain under active investigation.
4.3 Breastfeeding, HMOs, and Infant Microbiome Development
Exclusive breastfeeding during the first months of life significantly impacts infant gut microbiota composition. The mechanism is closely tied to HMO catabolism by bifidobacteria. Notably, B. bifidum emerged as the species with the highest HMO degradation capacity and the lowest antibiotic resistance, emphasizing its potential significance in early-life gut colonization; these findings underscore the pivotal role of breastfeeding in shaping the infant gut microbiome by promoting the growth of HMO-degrading bacteria, particularly bifidobacteria.
Breastfed human infants are predominantly colonized by bifidobacteria that thrive on HMO; two predominant species of bifidobacteria in infant feces are B. breve and B. longum subsp. infantis, both of which include avid HMO-consumer strains. The prevalence of bifidobacteria, especially B. infantis, in western populations is reduced compared to global populations, in particular relative to developing countries where breastfeeding rates and durations are historically higher.
Evidence strength: The relationship between breastfeeding, HMOs, and bifidobacterial colonization is well-established across multiple cohort studies and mechanistic investigations. Clinical data supporting supplementation of infant-type bifidobacteria to formula-fed infants to mimic this effect is growing but not yet universally standardized.
4.4 Mental Health: Depression, Anxiety, and the Gut-Brain Axis
Recent research has highlighted the gut-brain axis as a critical modulator of mental health, positioning probiotics as promising psychobiotic interventions for anxiety, stress, depression, and cognitive function; clinical trials investigating strains such as Bifidobacterium longum and multi-strain formulations have demonstrated strain- and context-specific effects on psychological and physiological outcomes.
Functional magnetic resonance imaging showed that Bifidobacterium longum NC3001 reduced the response of multiple brain regions (mainly including the amygdala and frontal limbic regions) to fear stimuli, and the decreased activation of the amygdala frontal limbic complex was related to decreased depression scores, suggesting that Bifidobacterium has a positive role in depression treatment.
A first-of-its-kind meta-analysis of bifidobacteria-related preparations and depression (PMC, 2024) noted that a meta-analysis of 13 randomized controlled trials supported the use of probiotics in people with mild to moderate depression; the results of another meta-analysis of 34 controlled clinical trials supported the efficacy of probiotics for depression and anxiety, with probiotics observed to have the greatest effect on major depressive disorder.
A systematic review of 51 psychobiotic RCTs involving 3,353 patients found that there was a notably high measurement of effectiveness specifically in the treatment of depression symptoms; most participants were older and female, with treatments commonly utilizing strains of Lactobacillus and bifidobacteria over periods ranging from 4 to 24 weeks. Bifidobacterium longum was highlighted as a significant strain in modulating various health conditions, both mental and physical.
Metabolite-based evidence: Mechanistic studies identified the aromatic lactate dehydrogenase (Aldh) gene as critical for ILA biosynthesis, and human studies demonstrated increased circulating ILA following Bifidobacterium breve supplementation in both depressed and healthy adults.
Evidence strength: Preliminary to moderate. Human RCT data are accumulating and several meta-analyses are encouraging, but the relationship between gut microbiota and anxiety and depression has limitations; while preclinical models have been invaluable for elucidating mechanistic pathways, current studies primarily involve animal models that cannot fully replicate the complexity of human neurobiology. Larger, more rigorously controlled trials with standardized strains and endpoints are needed.
4.5 Immune Function
The discovery of bifidobacteria in high numbers in healthy breastfed infants and the fermentative/acidulating nature of bifidobacteria have long implied a beneficial relationship in human nutrition and gastrointestinal health. More specifically, bifidobacterial colonization appears to play a role in training the neonatal immune system. Infants without Bifidobacteriaceae showed increased fecal calprotectin levels, which has implications on lifelong health, as intestinal inflammation early in life was predictive of an increased risk of developing autoimmune and allergic disease later in life.
B. infantis supplementation exhibited lowered fecal calprotectin and pro-inflammatory cytokines as well as reduced the incidence of antimicrobial resistance genes. In terms of pathogen resistance, in a landmark study, researchers in Japan demonstrated that production of acetate in situ by metabolically active bifidobacteria was protective against an otherwise lethal Escherichia coli O157:H7 infection.
Evidence strength: Strong mechanistic and observational evidence links bifidobacterial abundance to immune homeostasis, particularly in infancy. Interventional human data on immune endpoints in adults remains more heterogeneous.
4.6 Inflammatory Bowel Disease (IBD)
Cross-feeding interaction between bifidobacteria and Clostridiales, which produces butyrate, negatively correlates with inflammatory bowel disorders. While bifidobacteria have been studied as adjunctive therapies in IBD, most evidence is preliminary. The relationship between SCFAs produced by the gut microbiota and IBD — which includes Crohn's disease and ulcerative colitis — has been investigated; despite extensive research, the exact etiopathogenesis remains elusive, with a complex interplay involving genetic predisposition, environmental influences, and abnormal immune responses against commensal gut microbes widely recognized.
Evidence strength: Preclinical and mechanistic data are strong. High-quality clinical trial evidence specifically for bifidobacteria as monotherapy in IBD remains limited; this area requires further investigation.
5. Body Systems and Health Areas Associated with Bifidobacteria
- Gastrointestinal system: IBS symptom management (particularly abdominal pain and bloating); diarrhea and constipation; antibiotic-associated diarrhea; gut barrier integrity; NEC prevention in preterm infants; modulation of gut microbiota composition
- Immune system: Treg induction; dendritic cell and macrophage modulation; IgA stimulation; attenuation of Th2 and Th17 inflammatory programs; potential allergy prevention
- Central nervous system / Mental health: Gut-brain axis signaling; depression and anxiety (via vagal nerve, GABA synthesis, ILA production); emerging evidence for cognitive function
- Neonatal and pediatric health: Early-life gut colonization; support for immune system maturation; NEC risk reduction; HMO metabolism in breastfed and formula-fed infants
- Metabolic health: SCFA production influencing systemic glucose regulation, colonic energy homeostasis, and potentially inflammatory metabolic disease
6. Dosage Forms and Dosages Reported in Studies
Dosage in clinical research is expressed in colony-forming units (CFU). There is no single universally agreed therapeutic dose, and optimal dosing varies by species, strain, indication, and population.
- IBS trials (adults): The dose of total bifidobacteria ranged from 106 to >1011 CFU, with duration of supplementation ranging between 2 and 8 weeks, across 8 RCTs.
- B. longum 35624 in IBS: A significant reduction in abdominal pain in women with IBS was demonstrated at 1 Ă— 108 CFU per day; doses of 1 Ă— 106 and 1 Ă— 1010 CFU were not significantly effective in the same trial.
- NEC prevention in neonates: Oral administration of B. longum subsp. infantis and Lactobacillus acidophilus at a dose of 2.5 Ă— 108 CFU of each organism was used in one influential study for one year in neonates in an intensive-care unit.
- General adult probiotic use (B. animalis subsp. lactis): Typically administered in doses of 1 Ă— 109 to 1 Ă— 1011 CFU per day in clinical studies.
- Psychobiotic (mental health) trials: Treatments commonly utilized strains of bifidobacteria over periods ranging from 4 to 24 weeks.
Heat-inactivated (postbiotic) preparation: In a clinical trial of IBS, heat-inactivated B. bifidum MIMBb75 (SYN-HI-001) was administered orally as two capsules daily for eight weeks.
Production and delivery methodology is strain-specific and critical to efficacy. Bifidobacteria's strict anaerobic metabolism and sensitivity to gastric acid and processing conditions limit their viability during conventional administration, motivating the use of cryoprotectants, microencapsulation, and enteric-coated capsule technologies.
7. Safety Considerations and Notable Interactions
7.1 Regulatory Safety Status
The safety of bifidobacteria is well established, with several species classified as GRAS (generally regarded as safe) by the Food and Drug Administration (FDA) and QPS (qualified presumption of safety) by the European Food Safety Authority (EFSA), supporting their use as probiotics. The EFSA considers the bacterial species B. bifidum suitable for the QPS approach for safety assessment; the QPS approach is a generic assessment system used within EFSA to harmonize premarket safety assessments of selected groups of microorganisms used in food and food production, establishing safety of a defined taxon based on four pillars: (a) established identity, (b) body of knowledge, (c) possible pathogenicity, and (d) end use. EFSA likewise considers B. longum suitable for QPS safety assessment, which is a generic system to harmonize premarket safety assessments of microorganisms used in food and food production.
The genus Bifidobacterium constitutes one of the main groups of the human microbiota and some species have a long history of safe consumption supporting an excellent safety record.
7.2 Antibiotic Resistance: A Key Safety Concern
In the context of the increasing worldwide problems associated with the rise of pathogenic microorganisms with acquired resistance to antibiotics, the risk associated to the presence of antibiotic resistance determinants should always be a key starting point for the introduction of any microbial strain into the food chain; bifidobacteria are not an exception, and the presence of resistance to antibiotics is of interest since these microorganisms could potentially act as a reservoir of such resistances. It is therefore necessary to evaluate the presence of antibiotic resistance in any bifidobacterial strain to be included into the food chain.
Various lactic acid bacteria research groups have warned that some lactic acid bacteria consumed as food or feed may have antibiotic-resistant properties; since this resistance capability could be transferred to other pathogens via plasmids, the assessment of antibiotic resistance is an important criterion for evaluating the safety of strains used in food and feed. The EFSA guidelines consider the use of probiotics whose antibiotic-resistant profile could be transferable an important hazard.
Strain-level differences are important: phenotypic analysis revealed that B. bifidum strains had the lowest levels of antibiotic resistance, while Bifidobacterium animalis subsp. lactis strains were resistant to most tested antibiotics; overall, B. bifidum demonstrated the strongest HMO-degrading ability while remaining the most antibiotic-susceptible species.
The WHO/FAO working group recommended that new probiotic strains be evaluated for safety by testing for antibiotic resistance, toxin production and hemolytic potential, assessing metabolic activities such as D-lactate production and bile salt deconjugation, conducting human studies to evaluate side effects and post-market surveillance, and, ideally, studying their use in immunocompromised animals to determine infectivity.
7.3 Potential Adverse Events
Safety assessment of probiotic Bifidobacterium strains covers ammonia production, hemolysis of blood cells, biogenic amine production, antimicrobial susceptibility, antibiotic resistance gene transferability, mucin degradation, genome stability, and possession of virulence factors; in the case of the studied strains, neither hemolytic activity nor mucin degradation activity was found, and they did not produce ammonia or biogenic amines.
Although bifidobacteria have generally been regarded as safe (GRAS), there are theoretical concerns regarding their safety, including the potential for transmigration and consequently the occurrence of disease; bifidobacteria have been isolated from various clinical samples and reported as potential pathogens in rare instances. This is principally a concern in severely immunocompromised individuals. Bacteremia attributable to bifidobacteria has been described in rare case reports, though population-level incidence is very low.
A number of case reports describe episodes of infection caused by organisms consistent with probiotic strains in patients who consumed probiotics prior to symptom onset; the most commonly reported single probiotic-related infectious event in the broader category involves fungal species, not bifidobacteria. For bifidobacteria specifically, clinical infection in healthy, immunocompetent individuals is extremely rare across available postmarket surveillance data.
7.4 Viability and Interaction with Antibiotics
Antibiotic resistance is thought to cause changes in bowel habits and an increased risk of gastroenteritis, overweight, obesity, autoimmune and atopic diseases, and a low response to vaccines and cancer, likely mediated by antibiotic-induced gut dysbiosis; probiotic add-on therapy could partially prevent antibiotic-induced gut dysbiosis, but the antibiotic sensitivity features of probiotic strains likely limit this potential. In practice, administering bifidobacterial supplements several hours apart from antibiotic doses is recommended in clinical literature to minimize reduction in viability, though this timing effect is strain-specific.
References
Go back