Clinical and Bacteriologic Characteristics of Six Cases of Bifidobacterium breve Bacteremia Due to Probiotic Administration in the Neonatal Intensive Care Unit

Accounting for the health risk of probiotics

Probiotics have long been associated with a myriad of health benefits, so much so that their adverse effects whether mild or severe, are often neglected or overshadowed by the enormous volume of articles describing their beneficial effects in the current literature. Recent evidence has demonstrated several health risks of probiotics that warrant serious reconsideration of their applications and further investigations. This review aims to highlight studies that report on how probiotics might cause opportunistic systemic and local infections, detrimental immunological effects, metabolic disturbance, allergic reactions, and facilitating the spread of antimicrobial resistance. To offer a recent account of the literature, articles within the last five years were prioritized. The narration of these evidence was based on the nature of the studies in the following order of preference: clinical studies or human samples, in vivo or animal models, in situ, in vitro and/or in silico. We hope that this review will inform consumers, food scientists, and medical practitioners, on the health risks, while also encouraging research that will focus on and clarify the adverse effects of probiotics.

Bifidobacteria in disease: from head to toe

Bifidobacteria as a strictly anaerobic gram-positive bacteria, is widely distributed in the intestine, vagina and oral cavity, and is one of the first gut flora to colonize the early stages of life. Intestinal flora is closely related to health, and dysbiosis of intestinal flora, especially Bifidobacteria, has been found in a variety of diseases. Numerous studies have shown that in addition to maintaining intestinal homeostasis, Bifidobacteria may be involved in diseases covering all parts of the body, including the nervous system, respiratory system, genitourinary system and so on. This review collects evidence for the variation of Bifidobacteria in typical diseases among various systems, provides mild and effective therapeutic options for those diseases that are difficult to cure, and moves Bifidobacteria from basic research to further clinical applications.

Bacteraemia and obstructive pyelonephritis caused by Bifidobacterium breve in an elderly woman: a case report and literature review

Bifidobacterium spp. are non-spore-forming Gram-positive anaerobes that are indigenous to the human gastrointestinal tract and vagina. They are believed to be non-pathogenic organisms for humans and thus are widely used as probiotics. An 83-year-old woman taking cephalexin for 4 days was diagnosed with obstructive pyelonephritis. Y-branched Gram-positive rods were found in both anaerobic and aerobic blood culture bottles, and in an anaerobic urine culture. Bifidobacterium breve was finally identified. Ceftriaxone and metronidazole were administered to the patient, and she was discharged after intermittent catheterization for dysuria. Urinary tract infection caused by Bifidobacterium spp. is believed to be rare, but it can develop in patients with underlying urological conditions. Recognition of the characteristic morphology and conducting anaerobic urine culture may help in identifying more cases of Bifidobacterium urinary tract infections.

Probiotics to prevent necrotising enterocolitis in very preterm or very low birth weight infants

BACKGROUND

Intestinal dysbiosis may contribute to the pathogenesis of necrotising enterocolitis (NEC) in very preterm or very low birth weight (VLBW) infants. Dietary supplementation with probiotics to modulate the intestinal microbiome has been proposed as a strategy to reduce the risk of NEC and associated mortality and morbidity in very preterm or VLBW infants.

OBJECTIVES

To determine the effect of supplemental probiotics on the risk of NEC and associated mortality and morbidity in very preterm or very low birth weight infants.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, the Maternity and Infant Care database, and CINAHL from inception to July 2022. We searched clinical trials databases and conference proceedings, and examined the reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing probiotics with placebo or no probiotics in very preterm infants (born before 32 weeks' gestation) and VLBW infants (weighing less than 1500 g at birth).

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated risk of bias of the trials, extracted data, and synthesised effect estimates using risk ratios (RRs), risk differences (RDs), and mean differences (MDs), with associated 95% confidence intervals (CIs). The primary outcomes were NEC and all-cause mortality; secondary outcome measures were late-onset invasive infection (more than 48 hours after birth), duration of hospitalisation from birth, and neurodevelopmental impairment. We used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 60 trials with 11,156 infants. Most trials were small (median sample size 145 infants). The main potential sources of bias were unclear reporting of methods for concealing allocation and masking caregivers or investigators in about half of the trials. The formulation of the probiotics varied across trials. The most common preparations contained Bifidobacterium spp., Lactobacillus spp., Saccharomyces spp., andStreptococcus spp., alone or in combination. Very preterm or very low birth weight infants Probiotics may reduce the risk of NEC (RR 0.54, 95% CI 0.46 to 0.65; I² = 17%; 57 trials, 10,918 infants; low certainty). The number needed to treat for an additional beneficial outcome (NNTB) was 33 (95% CI 25 to 50). Probiotics probably reduce mortality slightly (RR 0.77, 95% CI 0.66 to 0.90; I² = 0%; 54 trials, 10,484 infants; moderate certainty); the NNTB was 50 (95% CI 50 to 100). Probiotics probably have little or no effect on the risk of late-onset invasive infection (RR 0.89, 95% CI 0.82 to 0.97; I² = 22%; 49 trials, 9876 infants; moderate certainty). Probiotics may have little or no effect on neurodevelopmental impairment (RR 1.03, 95% CI 0.84 to 1.26; I² = 0%; 5 trials, 1518 infants; low certainty). Extremely preterm or extremely low birth weight infants Few data were available for extremely preterm or extremely low birth weight (ELBW) infants. In this population, probiotics may have little or no effect on NEC (RR 0.92, 95% CI 0.69 to 1.22, I² = 0%; 10 trials, 1836 infants; low certainty), all-cause mortality (RR 0.92, 95% CI 0.72 to 1.18; I² = 0%; 7 trials, 1723 infants; low certainty), or late-onset invasive infection (RR 0.93, 95% CI 0.78 to 1.09; I² = 0%; 7 trials, 1533 infants; low certainty). No trials provided data for measures of neurodevelopmental impairment in extremely preterm or ELBW infants.

AUTHORS' CONCLUSIONS

Given the low to moderate certainty of evidence for the effects of probiotic supplements on the risk of NEC and associated morbidity and mortality for very preterm or VLBW infants, and particularly for extremely preterm or ELBW infants, there is a need for further large, high-quality trials to provide evidence of sufficient validity and applicability to inform policy and practice.

Gut Microbiome in Sepsis

Abstract The gut has been hypothesized to be the "motor" of multiple organ dysfunction in sepsis. Although there are multiple ways in which the gut can drive systemic inflammation, increasing evidence suggests that the intestinal microbiome plays a more substantial role than previously appreciated. An English language literature review was performed to summarize the current knowledge of sepsis-induced gut microbiome dysbiosis. Conversion of a normal microbiome to a pathobiome in the setting of sepsis is associated with worsened mortality. Changes in microbiome composition and diversity signal the intestinal epithelium and immune system resulting in increased intestinal permeability and a dysregulated immune response to sepsis. Clinical approaches to return to microbiome homeostasis may be theoretically possible through a variety of methods including probiotics, prebiotics, fecal microbial transplant, and selective decontamination of the digestive tract. However, more research is required to determine the efficacy (if any) of targeting the microbiome for therapeutic gain. The gut microbiome rapidly loses diversity with emergence of virulent bacteria in sepsis. Restoring normal commensal bacterial diversity through various therapies may be an avenue to improve sepsis mortality.

Update of the list of qualified presumption of safety (QPS) recommended microbiological agents intentionally added to food or feed as notified to EFSA 17: suitability of taxonomic units notified to EFSA until September 2022

The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of microorganisms, intended for use in the food or feed chains, to support the work of EFSA's Scientific Panels. The QPS approach is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of relevant knowledge and safety concerns. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at the species/strain or product level and reflected by 'qualifications'. In the period covered by this Statement, new information was found leading to the withdrawal of the qualification 'absence of aminoglycoside production ability' for Bacillus velezensis. The qualification for Bacillus paralicheniformis was changed to 'absence of bacitracin production ability'. For the other TUs, no new information was found that would change the status of previously recommended QPS TUs. Of 52 microorganisms notified to EFSA between April and September 2022 (inclusive), 48 were not evaluated because: 7 were filamentous fungi, 3 were Enterococcus faecium, 2 were Escherichia coli, 1 was Streptomyces spp., and 35 were taxonomic units (TUs) that already have a QPS status. The other four TUs notified within this period, and one notified previously as a different species, which was recently reclassified, were evaluated for the first time for a possible QPS status: Xanthobacter spp. could not be assessed because it was not identified to the species level; Geobacillus thermodenitrificans is recommended for QPS status with the qualification 'absence of toxigenic activity'. Streptoccus oralis is not recommended for QPS status. Ogataea polymorpha is proposed for QPS status with the qualification 'for production purposes only'. Lactiplantibacillus argentoratensis (new species) is included in the QPS list.

Probiotic supplementation for neonates with congenital gastrointestinal surgical conditions: guidelines for future research

Our pilot RCT found that probiotic supplementation with the three-strain bifidobacterial product (B. breve M-16V, B. longum subsp. infantis M-63 and B. longum subsp. longum BB536) attenuates gut dysbiosis, increases stool short-chain fatty acid (SCFA) levels and improves the growth of head circumference in neonates with congenital gastrointestinal surgical conditions (CGISC). In this article, we have provided guidelines for designing future multicentre RCTs based on the experience gained from our pilot RCT. The recommendations include advice about sample size, potential confounders, outcomes of interest, probiotic strain selection, storage, dose, duration and microbial quality assurance, collection of stool samples, storage and analysis and reporting. Following these guidelines will increase the validity of future RCTs in this area and hence confidence in their results. IMPACT: Probiotic supplementation attenuates gut dysbiosis, increases stool short-chain fatty acid (SCFA) levels and improves the growth of head circumference in neonates with congenital gastrointestinal surgical conditions. The current review provides evidence-based guidelines to conduct adequately powered RCTs in this field.

Probiotic sepsis in preterm neonates-a systematic review

Sepsis due to the administered probiotic strain/s is a barrier against adoption of prophylactic probiotic supplementation in preterm infants to reduce the risk of necrotising enterocolitis (NEC ≥ Stage II), all-cause mortality, late-onset sepsis, and feeding intolerance. We aimed to conduct a systematic review for reports of probiotic sepsis in preterm infants (gestation < 37 weeks). Databases including PubMed, Embase, Emcare, Cochrane Central library, and Google Scholar were searched in August 2021 and updated in Jan 2022. Probiotic sepsis was defined as positive blood/CSF culture isolating administered probiotic strain with symptoms suggestive of infection. Data collection included birth weight, gestation, comorbidities (e.g. gut surgery, NEC), presence of central venous catheters, treatment, and outcome. Literature search revealed 1569 studies. A total of 16 reports [randomised control trial (RCT): none; non-RCT: 1; case series: 8; case report: 7] involving 32 preterm infants with probiotic sepsis were included after exclusions for various reasons. Majority of the cases were born < 32 weeks' gestation. Bifidobacterium (N = 19) was the most commonly isolated organism followed by Lactobacillus (N = 10), and Saccharomyces (N = 3). A total of 25/32 cases were confirmed to be due to the administered probiotic strain on full genomic analysis. Two studies reported one neonatal death each. Twelve neonates had comorbidities. Majority were treated with antibiotics (29/32) whereas others (3/32) required antifungal treatment.

CONCLUSION

Probiotics sepsis is relatively an uncommon event in preterm infants. Majority of the cases recovered after antibiotic or antifungal treatment. The importance of optimal surveillance and treatment of probiotic sepsis and research towards alternatives to probiotics (e.g. postbiotics) is emphasised.

WHAT IS KNOWN

• Probiotics have been shown to reduce necrotising enterocolitis, late-onset sepsis, all-cause mortality, and time to reach full enteral feeds in preterm infants. • Despite the evidence, use of probiotics is not universal due to concerns regarding probiotic-associated sepsis in preterm infants.

WHAT IS NEW

• This comprehensive systematic review showed that probiotic sepsis is a relatively rare phenomenon in preterm infants. • All except one case where the diagnosis was uncertain recovered after antimicrobial therapy.