Probiotics in critically ill children

A review for non-antibiotic treatment of Helicobacter pylori: new insight

Gastric ulcers and gastric cancer are brought on by the Helicobacter pylori bacteria, which colonizes under the stomach mucous membrane. Different medication regimens are used to remove it, but the illness returns and becomes more resistant, which lowers the treatment rates. Additionally, this bacterium now exhibits a skyrocketing level of multi-drug resistance, necessitating recurrent therapeutic treatments. The negative effects of synthetic medications in comparison to conventional therapies are another significant factor in favor of non-pharmacological therapy. The most significant side effects of popular anti-gastric ulcer medications include nausea, vomiting, and diarrhea. Stomach ulcers have previously been treated with herbal remedies and complementary treatments like probiotics. When probiotics are ingested, the host experiences several advantages that may be brought about by altering the bacterial flora in the digestive system. Additionally, stronger-acting chemical compounds and plant extracts can be employed to treat patients. In this article, we look at the substances and medications that are utilized in place of synthetic stomach ulcer-curing treatments.

Study of the gut microbiome as a novel target for prevention of hospital-associated infections in intensive care unit patients

BACKGROUND

Hospital-acquired infections (HAIs) are increasing due to the spread of multi-drugresistant organisms. Gut dysbiosis in an intensive care unit (ICU) patients at admission showed an altered abundance of some bacterial genera associated with the occurrence of HAIs and mortality. In the present study, we investigated the pattern of the gut microbiome in ICU patients at admission to correlate it with the development of HAIs during ICU stay.

METHODS

Twenty patients admitted to an ICU with a cross-matched control group of 30 healthy subjects of matched age and sex. Quantitative SYBR green real-time polymerase chain reaction was done for the identification and quantitation of selected bacteria.

RESULTS

Out of those twenty patients, 35% developed ventilator-associated pneumonia during their ICU stay. Gut microbiome analysis showed a significant decrease in Firmicutes and Firmicutes to Bacteroidetes ratio in ICU patients in comparison to the control and in patients who developed HAIs in comparison to the control group and patients who did not develop HAIs. There was a statistically significant increase in Bacteroides in comparison to the control group. There was a statistically significant decrease in Bifidobacterium and Faecalibacterium prausnitzii and an increase in Lactobacilli in comparison to the control group with a negative correlation between Acute Physiology and Chronic Health Evaluation (APACHE) II score and Firmicutes to Bacteroidetes and Prevotella to Bacteroides ratios.

CONCLUSIONS

Gut dysbiosis of patients at the time of admission highlights the importance of identification of the microbiome of patients admitted to the ICU as a target for preventing of HAIs.

Probiotics media: significance, challenges, and future perspective - a mini review

The health benefits associated with probiotics have increased their application in pharmaceutical formulations and functional food development. High production of probiotic biomass requires a cost-effective production method and nutrient media optimization. The biomass production of probiotics can be enhanced by optimizing growth parameters such as substrate, pH, incubation time, etc. For economical industrial production of probiotic biomass, it is required to design a new medium with low cost. Wastes from the food industries are promising components for the development of the low-cost medium. Industrial wastes such as cheese whey and corn steep liquor are excellent examples of reliable sources of nitrogen for the biomass production of probiotic bacteria. The increased yield of biomass reduced the cost of production. This review focuses on the importance of probiotic media for biomass production and its challenges.

Graphical Abstract

Bidirectional effects of intestinal microbiota and antibiotics: a new strategy for colorectal cancer treatment and prevention

PURPOSE

Colorectal cancer (CRC) is the third most common cancer worldwide, and its incidence and mortality rates are increasing every year. The intestinal microbiota has been called the "neglected organ" and there is growing evidence that the intestinal microbiota and its metabolites can be used in combination with immunotherapy, radiotherapy and chemotherapy to greatly enhance the treatment of colorectal cancer and to address some of the side effects and adverse effects of these therapies. Antibiotics have great potential to eliminate harmful microbiota, control infection, and reduce colorectal cancer side effects. However, the use of antibiotics has been a highly controversial issue, and numerous retrospective studies have shown that the use of antibiotics affects the effectiveness of treatment (especially immunotherapy). Understanding the bi-directional role of the gut microbiota and antibiotics will further enhance our research into the diagnosis and treatment of cancer.

METHODS

We searched the "PubMed" database and selected the following keywords "intestinal microbiota, antibiotics, treatment, prevention, colorectal cancer". In this review, we discuss the role of the intestinal microbiota in immunotherapy, radiotherapy, chemotherapy, diagnosis, and prevention of CRC. We also conclude that the intestinal microbiota and antibiotics work together to promote the treatment of CRC through a bidirectional effect.

RESULTS

We found that the intestinal microbiota plays a key role in promoting immunotherapy, chemotherapy, radiotherapy, diagnosis and prevention of CRC. In addition, gut microbiota and antibiotic interactions could be a new strategy for CRC treatment.

CONCLUSION

The bi-directional role of the intestinal microbiota and antibiotics plays a key role in the prevention, diagnosis, and treatment of colorectal cancer.

The Lactobacillus as a Probiotic: Focusing on Liver Diseases

Over the past decade, scientific evidence for the properties, functions, and beneficial effects of probiotics for humans has continued to accumulate. Interest in the use of probiotics for humans has increased tremendously. Among various microorganisms, probiotics using bacteria have been widely studied and commercialized, and, among them, Lactobacillus is representative. This genus contains about 300 species of bacteria (recently differentiated into 23 genera) and countless strains have been reported. They improved a wide range of diseases including liver disease, gastrointestinal diseases, respiratory diseases, and autoimmune diseases. Here, we intend to discuss in depth the genus Lactobacillus as a representative probiotic for chronic liver diseases.

Protective Effects of Probiotics on Cognitive and Motor Functions, Anxiety Level, Visceral Sensitivity, Oxidative Stress and Microbiota in Mice with Antibiotic-Induced Dysbiosis

Accumulating clinical and preclinical data indicate a prominent role of gut microbiota in regulation of physiological functions. The gut-brain axis imbalance due to gut dysbiosis is associated with a range of neurodegenerative diseases. Probiotics were suggested not only to restore intestinal dysbiosis but also modulate stress response and improve mood and anxiety symptoms. In this study, we assessed the effects of probiotic lactobacilli on behavioral reactions, the level of oxidative stress and microbiota content in mice administered to broad-spectrum antibiotics. Our study demonstrates that antibiotic treatment of adolescent mice for two weeks resulted in higher mortality and lower weight gain and induced significant changes in behavior including lower locomotor and exploratory activity, reduced muscle strength, visceral hypersensitivity, higher level of anxiety and impaired cognitive functions compared to the control group. These changes were accompanied by decreased diversity and total amount of bacteria, abundance of Proteobacteria and Verrucomicrobia phyla, and reduced Firmicutes/Bacteroides ratio in the gut microbiota. Moreover, a higher level of oxidative stress was found in brain and skeletal muscle tissues of mice treated with antibiotics. Oral administration of two Lactobacillus strains prevented the observed changes and improved not only microbiota content but also the behavioral alterations, suggesting a neuroprotective and antioxidant role of probiotics.

Application of probiotics in candidiasis management

Candidiasis (e.g., oral, gastrointestinal, vaginal, urinary tract, systemic) is a worldwide growing problem, since antifungal resistance and immunosuppression states are rising. To address this problem, very few drugs are available for the treatment of Candida spp. infections. Therefore, novel therapeutic strategies are urgently required. Probiotics have been proposed for the prevention and treatment of bacterial infections due to their safety record and efficacy, however, little is still known about their potential role regarding fungal infections. The purpose of this review is to present an updated summary of the evidence of the antifungal effects of probiotics along with a discussion of their potential use as an alternative/complementary therapy against Candida spp. infections. Thus, we performed a literature search using appropriate keywords ("Probiotic + Candida", "Candidiasis treatment", and "Probiotic + candidiasis") to retrieve relevant studies (both preclinical and clinical) with special emphasis on the works published in the last 5 years. An increasing amount of evidence has shown the potential usefulness of probiotics in the management of oral and vulvovaginal candidiasis in recent years. Among other results, we found that, as for bacterial infections, Lactobacillus, Bifidobacterium, and Saccharomyces are the most studied and effective genus for this purpose. However, in other areas, particularly in skincandidiaisis, studies are low or lacking. Thus, further investigation is necessary including in vitro and in vivo studies to establish the usefulness of probiotics in the management of candidiasis.

Assessment of the Safety of Lactobacillus casei IMV B-7280 Probiotic Strain on a Mouse Model

Probiotics, in particular Lactobacillus (lactic acid bacteria, LAB) strains, are widely used in clinical practice. Despite that these probiotics have GRAS (generally regarded as safe) and qualified presumption of safety (QPS) statuses, the safety of particular strains still needs to be thoroughly studied. The aim of the study was to evaluate the safety of Lact. casei IMV B-7280 strain by investigating toxicity and the effects on gut microbiota in experimental animal model. Male BALB/c mice (7-8 weeks, weight 20-24 g) were treated with amounts of Lact. casei IMV B-7280 strain: 5 × 10⁶, 5 × 10⁸, or 5 × 10⁹ CFU/animal once per day during 7 days, or in the amount of 1 × 10¹⁰ CFU/animal once per day during 3 days (most of the proposed probiotic doses for humans-from 10⁸ to 10⁹ CFU) and monitored during 14 days. Blood tests and serum biochemistry were conducted; the cecal content from mice of the experimental and control groups were freshly collected and analyzed. At the end of the experiments (15th day), the presence of LAB in the heart, liver, kidney, and mesenteric lymph nodes and peripheral blood was determined; histology of the brain, liver, heart, fragments of the small and large intestine, and mesenteric lymph nodes was conducted. Survival rate of BALB/c mice treated with Lact. casei IMV B-7280 strain in different concentrations in toxicity experiments during 14 days was 100%. We observed no signs of toxicity as changes in gait, lethargy, sleep, somatomotor activity as well as changes in fur, eyes, skin and mucous membranes, tremors, behavior pattern, convulsions, salivation, diarrhea, and local injuries in mice from all experimental groups. After administration of probiotic strain, the number of opportunistic bacteria in cecal contents, such as Staphylococcus spp., Candida spp., Pseudomonas spp., and total aerobic and optionally anaerobic bacteria decreased compared to controls; the population of beneficial bacteria such as lactobacilli increased in cecal contents of these mice. LAB were not detected in the peripheral blood, heart, liver, kidneys, and mesenteric lymph nodes after administration of this strain to intact mice. Lact. casei IMV B-7280 strain is safe at dose up to 10¹⁰ CFU/animal during 3- and 7-day oral administration to mice and has a positive effect on the gut microbiota composition; it could be potentially considered as safe probiotic for humans.

Do Probiotics During In-Hospital Antibiotic Treatment Prevent Colonization of Gut Microbiota With Multi-Drug-Resistant Bacteria? A Randomized Placebo-Controlled Trial Comparing Saccharomyces to a Mixture of Lactobacillus, Bifidobacterium, and Saccharomyces

Objective: Most infections with Enterobacteriaceae producing AmpC β-lactamase (AmpC)-, extended-spectrum β-lactamase (ESBL)-, and carbapenemase-producing bacteria, vancomycin-resistant Enterococcus as well as naturally resistant non-fermenting bacteria such as Pseudomonas aeruginosa, are related to a prior colonization of the gut microbiota. The objective of this study was to determine whether treatment with probiotics during an antibiotic treatment could prevent the colonization of the gut microbiota with multi-drug resistant bacteria.

Method: In total, 120 patients treated for 10 days with amoxicillin-clavulanate antibiotics were included in a randomized, placebo-controlled, double-blinded trial, comparing the effects of a 30 days treatment with placebo Saccharomyces boulardii CNCM I-745® and a probiotic mixture containing Saccharomyces boulardii, Lactobacillus acidophilus NCFM, Lactobacillus paracasei Lpc-37, Bifidobacterium lactis Bl-04, and Bifidobacterium lactis Bi-07 (Bactiol duo®). Study treatment was initiated within 48 h of the antibiotic being initiated. Most of the patients included were elderly with a mean age of 78 years old with multiple comorbidities. Stools were collected at the time of inclusion in the trial, at the end of the antibiotic treatment, and the end of the study treatment. These were cultured on selective antibiotic media.

Results: Treatment with the probiotic mixture led to a significant decline in colonization with Pseudomonas after antibiotic treatment from 25 to 8.3% (p = 0.041). Colonization with AmpC-producing enterobacteria was transiently increased after the antibiotic treatment (p = 0.027) and declined after the probiotic intervention (p= 0.041). No significant changes were observed in the placebo and Saccharomyces groups. Up to 2 years after the trial, no infection with ESBL-producing bacteria was observed in the probiotic mixture group.

Conclusion: The association of Saccharomyces boulardii with specific strains of Lactobacillus and Bifidobacterium influences antibiotic treatment by counteracting the colonization of the colon microbiota with antibiotic-resistant pathogens.

Effect of Simulated Gastrointestinal Tract Conditions on Survivability of Probiotic Bacteria Present in Commercial Preparations

Probiotics are recommended, among others, in the diet of children who are under antibiotic therapy, or that suffer from food allergies or travel diarrhea, etc. In the case of toddlers taking probiotic preparations, it is highly recommended to first remove the special capsule, which normally protects probiotic strains against hard conditions in the gastrointestinal tract. Otherwise, the toddler may choke. This removal can impair probiotic survival and reduce its efficacy in a toddler’s organism. The aim of this study was to evaluate the survivability of five strains of lactic acid bacteria from the commercial probiotics available on the Polish market under simulated conditions of the gastrointestinal tract. Five probiotics (each including one of these strains: Bifidobacterium BB-12, Lactobacillus (Lb.) rhamnosus GG, Lb. casei, Lb. acidophilus, Lb. plantarum) were protective capsule deprived, added in a food matrix (chicken–vegetable soup) and subjected under simulated conditions of the gastric and gastrointestinal passage. Strain survivability and possibility to growth were evaluated. Obtained results showed that, among all analyzed commercial probiotic strains, the Lb. plantarum was the most resistant to the applied conditions of the culture medium. They showed a noticeable growth under both in vitro gastric conditions at pH 4.0 and 5.0, as well as in vitro intestinal conditions at all tested concentrations of bile salts.

Efficacy of probiotics in the prevention of VAP in critically ill ICU patients: an updated systematic review and meta-analysis of randomized control trials

Introduction

Ventilator-associated pneumonia (VAP) is reported as the second most common nosocomial infection among critically ill patients with the incidence ranging from 2 to 16 episodes per 1000 ventilator days. The use of probiotics has been shown to have a promising effect in many RCTs. Our systematic review and meta-analysis were thus planned to determine the effect of probiotic use in critically ill ventilated adult patients on the incidence of VAP, length of hospital stay, length of ICU stay, duration of mechanical ventilation, the incidence of diarrhea, and the incidence of oropharyngeal colonization and in-hospital mortality.

Methodology

Systematic search of various databases (such as Embase, Cochrane, and Pubmed), published journals, clinical trials, and abstracts of the various major conferences were made to obtain the RCTs which compare probiotics with placebo for VAP prevention. The results were expressed as risk ratios or mean differences. Data synthesis was done using statistical software - Review Manager (RevMan) Version 5.4 (The Cochrane Collaboration, 2020).

Results

Nine studies met our inclusion criterion and were included in the meta-analysis. The incidence of VAP (risk ratio: 0.70, CI 0.56, 0.88; P = 0.002; I² = 37%), duration of mechanical ventilation (mean difference −3.75, CI −6.93, −0.58; P 0.02; I² = 96%), length of ICU stay (mean difference −4.20, CI −6.73, −1.66; P = 0.001; I² = 84%) and in-hospital mortality (OR 0.73, CI 0.54, 0.98; P = 0.04; I² = 0%) in the probiotic group was significantly lower than that in the control group. Probiotic administration was not associated with a statistically significant reduction in length of hospital stay (MD −1.94, CI −7.17, 3.28; P = 0.47; I² = 88%), incidence of oro-pharyngeal colonization (OR 0.59, CI 0.33, 1.04; P = 0.07; I² = 69%), and incidence of diarrhea (OR 0.59, CI 0.34, 1.03; P = 0.06; I² = 38%).

Discussion

Our meta-analysis shows that probiotic administration has a promising role in lowering the incidence of VAP, the duration of mechanical ventilation, length of ICU stay, and in-hospital mortality.

Probiotics and Coronavirus disease 2019: think about the link

The pandemic of Coronavirus disease 2019 (COVID-19) is rapidly progressing, causing significant morbidity and mortality. Various antiviral drugs, anti-inflammatory drugs and immunomodulators have been tried without substantial clinical benefits. The severe and critical cases of COVID-19 disease are characterised by gut microbiome dysbiosis, immune dysregulation, hyper-inflammation and hypercytokinaemia (cytokine storm). Therefore, the strategies which target these pathophysiological processes may be beneficial. Probiotics are one such strategy that exerts beneficial effects by manipulation of the gut microbiota, suppression of opportunistic pathogens in the gut, decreasing translocation of opportunistic organisms, activation of mucosal immunity and modulation of the innate and adaptive immune response. Probiotics are the potential candidates to be tested in moderate and severe cases of COVID-19 due to several beneficial effects, including easy availability, easy to administer, safe and economical to use.

How Probiotics Affect the Microbiota

Probiotics have been used to treat a variety of diseases for decades; however, what is the rationale for their application? Such a treatment was first proposed in the early nineteenth century based on observations of decreased bifidobacterial populations in children suffering from diarrhea, suggesting that oral intake of bifidobacteria could replete this subpopulation of the microbiota and improve health. Since then, studies have shown modifications in the gut or skin microbiota in the course of a variety of diseases and suggested positive effects of certain probiotics. Most studies failed to report any impact on the microbiota. The impact of probiotics as well as of bacteria colonizing food does not reside in their ability to graft in the microbiota but rather in sharing genes and metabolites, supporting challenged microbiota, and directly influencing epithelial and immune cells. Such observations argue that probiotics could be associated with conventional drugs for insulin resistance, infectious diseases, inflammatory diseases, and psychiatric disorders and could also interfere with drug metabolism. Nevertheless, in the context of a plethora of probiotic strains and associations produced in conditions that do not allow direct comparisons, it remains difficult to know whether a patient would benefit from taking a particular probiotic. In other words, although several mechanisms are observed when studying a single probiotic strain, not all individual strains are expected to share the same effects. To clarify the role of probiotics in the clinic, we explored the relation between probiotics and the gut and skin microbiota.

Modification of Immunological Parameters, Oxidative Stress Markers, Mood Symptoms, and Well-Being Status in CFS Patients after Probiotic Intake: Observations from a Pilot Study

The present study discusses about the effects of a combination of probiotics able to stimulate the immune system of patients affected by Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). To this purpose, patients diagnosed according to Fukuda's criteria and treated with probiotics were analyzed by means of clinical and laboratory evaluations, before and after probiotic administrations. Probiotics were selected considering the possible pathogenic mechanisms of ME/CFS syndrome, which has been associated with an impaired immune response, dysregulation of Th1/Th2 ratio, and high oxidative stress with exhaustion of antioxidant reserve due to severe mitochondrial dysfunction. Immune and oxidative dysfunction could be related with the gastrointestinal (GI) chronic low-grade inflammation in the lamina propria and intestinal mucosal surface associated with dysbiosis, leaky gut, bacterial translocation, and immune and oxidative dysfunction. Literature data demonstrate that bacterial species are able to modulate the functions of the immune and oxidative systems and that the administration of some probiotics can improve mucosal barrier function, modulating the release of proinflammatory cytokines, in CFS/ME patients. This study represents a preliminary investigation to verifying the safety and efficacy of a certain combination of probiotics in CFS/ME patients. The results suggest that probiotics can modify the well-being status as well as inflammatory and oxidative indexes in CFS/ME patients. No adverse effects were observed except for one patient, which displayed a flare-up of symptoms, although all inflammatory parameters (i.e., cytokines, fecal calprotectin, ESR, and immunoglobulins) were reduced after probiotic intake. The reactivation of fatigue symptoms in this patient, whose clinical history reported the onset of CFS/ME following mononucleosis, could be related to an abnormal stimulation of the immune system as suggested by a recent study describing an exaggerated immune activation associated with chronic fatigue.

In Vitro Antimicrobial Activity and Probiotic Potential of Bifidobacterium and Lactobacillus against Species of Clostridium

Many Clostridium species are found as commensal members of the intestinal microbiota. However, imbalances of the microbiota may lead to certain infections caused by these microorganisms, mainly Clostridium butyricum, Clostridium difficile, and Clostridium perfringens. In many cases, infection recurrence can occur after antibiotics, indicating the need for novel therapeutic options that act on the pathogens and also restore the microbiota. Herein, the in vitro antimicrobial activity and probiotic potential of clinical and reference strains of Bifidobacterium and Lactobacillus were investigated against Clostridium species. Antimicrobial activity was evaluated by the agar spot test and inhibition of gas production. Then, the probiotic potential of selected strains was assessed by analyzing their coaggregation ability, adhesive properties to host cells and mucin, tolerance to acidic pH and bile salts, and antimicrobial susceptibility profiles. Lactobacillus plantarum ATCC 8014 was the most promising strain based on its inhibitory activity against Clostridium spp. Also, this strain met criteria to be considered a probiotic based on its coaggregation ability, adhesive properties, and tolerance to harsh pH and bile acid salt conditions. The results indicate that among the studied strains, L. plantarum ATCC 8014 presents probiotic potential for controlling infections induced by the studied Clostridium species and should be further evaluated in in vivo animal models.

The Role of the Environment and Colonization in Healthcare-Associated Infections

Healthcare-associated infections (HAIs) can be caused by endogenous host microbial flora or by exogenous microbes, including those found in the hospital environment. Efforts to decrease endogenous pathogens via decolonization and skin antisepsis may decrease the risk of infection in some settings. Controlling the spread of potential pathogens from the environment requires meticulous attention to cleaning and disinfection practices. In addition to selection of the appropriate cleaning agent, use of tools that assess the adequacy of cleaning and addition of no-touch cleaning technology may decrease environmental contamination. Hand hygiene is also a critical component of preventing transmission of pathogens from the environment to patients via healthcare worker hands.

Use of Probiotics in the Prevention of Nosocomial Infections

Nosocomial, hospital-acquired or health care-associated infections occur worldwide, affecting both developed and developing countries. This results in a prolonged hospital stay, increased antimicrobial resistance, increased mortality rate, and significant financial burden on the health care system. Routine preventive measures have led to the decrease in infection spreading; however, it cannot successfully prevent all of them, making a place for the development of new strategies, including probiotics. The aim of this review was to summarize available evidence of the role of probiotics in the prevention of nosocomial infections in children. Currently there is enough evidence showing that Lactobacillus rhamnosus GG administrated in a dose of at least 10 colony-forming units per day during the hospital stay can significantly reduce a risk for nosocomial diarrhea at regular pediatric ward. For other indications including the risk of respiratory tract infections at regular pediatric ward or risk of nosocomial infections at intensive care units we do not have enough evidence to give a recommendation. Therefore, additional research is needed to increase our knowledge and possibly further improve clinical practice.

The potential role of microbiota for controlling the spread of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) in neonatal population

The spread of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) in the hospital and also the community is worrisome. Neonates particularly are exposed to the risk of ESBL-PE acquisition and, owing to the immaturity of their immune system, to a higher secondary risk of ESBL-PE-related infection. Reducing the risk of acquisition in the hospital is usually based on a bundle of measures, including screening policies at admission, improving hand hygiene compliance, and decreasing antibiotic consumption. However, recent scientific data suggest new prevention opportunities based on microbiota modifications.

Bifidobacterium Bacteremia: Clinical Characteristics and a Genomic Approach To Assess Pathogenicity

Bifidobacteria are commensals that colonize the orogastrointestinal tract and rarely cause invasive human infections. However, an increasing number of bifidobacterial blood culture isolates has lately been observed in Norway. In order to investigate the pathogenicity of the Bifidobacterium species responsible for bacteremia, we studied Bifidobacterium isolates from 15 patients for whom cultures of blood obtained from 2013 to 2015 were positive. We collected clinical data and analyzed phenotypic and genotypic antibiotic susceptibility. All isolates (11 Bifidobacterium longum, 2 B. breve, and 2 B. animalis isolates) were subjected to whole-genome sequencing. The 15 patients were predominantly in the extreme lower or upper age spectrum, many were severely immunocompromised, and 11 of 15 had gastrointestinal tract-related conditions. In two elderly patients, the Bifidobacterium bacteremia caused a sepsis-like picture, interpreted as the cause of death. Most bifidobacterial isolates had low MICs (≤0.5 mg/liter) to beta-lactam antibiotics, vancomycin, and clindamycin and relatively high MICs to ciprofloxacin and metronidazole. We performed a pangenomic comparison of invasive and noninvasive B. longum isolates based on 65 sequences available from GenBank and the sequences of 11 blood culture isolates from this study. Functional annotation identified unique genes among both invasive and noninvasive isolates of Bifidobacterium Phylogenetic clusters of invasive isolates were identified for a subset of the B. longum subsp. longum isolates. However, there was no difference in the number of putative virulence genes between invasive and noninvasive isolates. In conclusion, Bifidobacterium has an invasive potential in the immunocompromised host and may cause a sepsis-like picture. Using comparative genomics, we could not delineate specific pathogenicity traits characterizing invasive isolates.