Lactobacilli Infection Case Reports in the Last Three Years and Safety Implications

Two intestinal microbiota-derived metabolites, deoxycholic acid and butyrate, synergize to enhance host defense peptide synthesis and alleviate necrotic enteritis

BACKGROUND

Necrotic enteritis (NE) is a major enteric disease in poultry, yet effective mitigation strategies remain elusive. Deoxycholic acid (DCA) and butyrate, two major metabolites derived from the intestinal microbiota, have independently been shown to induce host defense peptide (HDP) synthesis. However, the potential synergy between these two compounds remains unexplored.

METHODS

To investigate the possible synergistic effect between DCA and butyrate in regulating HDP synthesis and barrier function, we treated chicken HD11 macrophage cells and jejunal explants with DCA and sodium butyrate (NaB), either individually or in combination, for 24 h. Subsequently, we performed RNA isolation and reverse transcription-quantitative PCR to analyze HDP genes as well as the major genes associated with barrier function. To further determine the synergy between DCA and NaB in enhancing NE resistance, we conducted two independent trials with Cobb broiler chicks. In each trial, the diet was supplemented with DCA or NaB on the day-of-hatch, followed by NE induction through sequential challenges with Eimeria maxima and Clostridium perfringens on d 10 and 14, respectively. We recorded animal mortality after infection and assessed intestinal lesions on d 17. The impact of DCA and NaB on the microbiota in the ileum and cecum was evaluated through bacterial 16S rRNA gene sequencing.

RESULTS

We found that the combination of DCA and NaB synergistically induced multiple HDP genes in both chicken HD11 cells and jejunal explants. Additionally, the gene for claudin-1, a major tight junction protein, also exhibited synergistic induction in response to DCA and NaB. Furthermore, dietary supplementation with a combination of 0.75 g/kg DCA and 1 g/kg NaB led to a significant improvement in animal survival and a reduction in intestinal lesions compared to either compound alone in a chicken model of NE. Notably, the cecal microbiota of NE-infected chickens showed a marked decrease in SCFA-producing bacteria such as Bacteroides, Faecalibacterium, and Cuneatibacter, with lactobacilli becoming the most dominant species. However, supplementation with DCA and NaB largely restored the intestinal microbiota to healthy levels.

CONCLUSIONS

DCA synergizes with NaB to induce HDP and claudin-1 expression and enhance NE resistance, with potential for further development as cost-effective antibiotic alternatives.

Under conditions closely mimicking vaginal fluid, Lactobacillus jensenii strain 62B produces a bacteriocin-like inhibitory substance that targets and eliminates Gardnerella species

Within the vaginal ecosystem, lactobacilli and Gardnerella spp. likely interact and influence each other's growth, yet the details of this interaction are not clearly defined. Using medium simulating vaginal fluid and a two-chamber co-culturing system to prevent cell-to-cell contact between the bacteria, we examined the possibility that Lactobacillus jensenii 62B (Lj 62B) and/or G. piotii (Gp) JCP8151B produce extracellular factors through which they influence each other's viability. By 24 h post-inoculation (hpi) in the co-culture system and under conditions similar to the vaginal environment - pH 5.0, 37 °C, and 5% CO2, Lj 62B viability was not affected but Gp JCP8151B had been eliminated. Cell-free supernatant harvested from Lj 62B cultures (Lj-CFS) at 20 hpi, but not 16 hpi, also eliminated Gp JCP8151B growth. Neither lactic acid nor H2O2 production by Lj 62B was responsible for this effect. The Lj-CFS did not affect viability of three species of lactobacilli or eight species of Gram-positive and Gram-negative uropathogens but eliminated viability of eight different strains of Gardnerella spp. Activity of the inhibitory factor within Lj-CFS was abolished by protease treatment and reduced by heat treatment suggesting it is most likely a bacteriocin-like protein; fractionation revealed that the factor has a molecular weight within the 10-30 kDa range. These results suggest that, in medium mimicking vaginal fluid and growth conditions similar to the vaginal environment, Lj 62B produces a potential bacteriocin-like inhibitory substance (Lj-BLIS) that clearly targets Gardnerella spp. strains. Once fully characterized, Lj-BLIS may be a potential treatment for Gardnerella-related BV that does not alter the vaginal microflora.

From air to airway: Dynamics and risk of inhalable bacteria in municipal solid waste treatment systems

Municipal solid waste treatment (MSWT) system emits a cocktail of microorganisms that jeopardize environmental and public health. However, the dynamics and risks of airborne microbiota associated with MSWT are poorly understood. Here, we analyzed the bacterial community of inhalable air particulates (PM10, n = 71) and the potentially exposed on-site workers' throat swabs (n = 30) along with waste treatment chain in Shanghai, the largest city of China. Overall, the airborne bacteria varied largely in composition and abundance during the treatment (P < 0.05), especially in winter. Compared to the air conditions, MSWT-sources that contributed to 15 ∼ 70% of airborne bacteria more heavily influenced the PM10-laden bacterial communities (PLS-SEM, β = 0.40, P < 0.05). Moreover, our year-span analysis found PM10 as an important media spreading pathogens (104 ∼ 108 copies/day) into on-site workers. The machine-learning identified Lactobacillus and Streptococcus as pharynx-niched featured biomarker in summer and Rhodococcus and Capnocytophaga in winter (RandomForest, ntree = 500, mtry = 10, cross = 10, OOB = 0%), which closely related to their airborne counterparts (Procrustes test, P < 0.05), suggesting that MSWT a dynamic hotspot of airborne bacteria with the pronounced inhalable risks to the neighboring communities.

Lactobacillus rhamnosus Infective Endocarditis in an Elderly Male

Lactobacilli are facultative anaerobic, gram-positive, rod-shaped bacteria found in the normal flora of the oral cavity and the gastrointestinal and genitourinary tracts. This report presents a case of Lactobacillus rhamnosus infective endocarditis and provides echocardiographic evidence of its pathogenic potential. Furthermore, we provide an account of the first successful treatment with daptomycin to our knowledge. Additionally, we examine the limited literature available on this microbiological entity and attempt to relate this data to our case.

Vertebral osteomyelitis due to Lactobacillus paracasei in a diabetic patient. A case report and literature review

Staphylococci are the most frequent cause of vertebral osteomyelitis, but infections due to unusual pathogens are also reported. We describe a rare case of spondylodiscitis due to Lactobacillus paracasei. A 74-year-old diabetic male was evaluated for fever and back pain. Blood cultures and vertebral biopsy were positive for Lactobacillus paracasei. He often took laxatives and probiotics for chronic constipation. After target treatment the patient improved but he died for a heart attack two months after the end of the treatment. Although Lactobacillus paracasei is usually not pathogenic, sepsis is described in immunocompromised patients while vertebral osteomyelitis is rare.

Bacteraemia caused by Lactobacillus casei in a patient after cardiac surgery. A case report

BACKGROUND

Bacteria of the Lactobacillus family are a part of the physiological flora of the oral cavity, gastrointestinal tract, and urinary tract. We have used them in the food industry as probiotics and supplements. In some settings, rod-shaped lactic acid bacteria may become pathogenic. It may occur in immunocompromised or heart disease patients after cardiac surgery, patients with disturbed intestinal wall permeability, or those treated with broad-spectrum antibiotics.

CASE PRESENTATION

We present rare bacteraemia induced by the probiotic bacterium Lactobacillus casei in a 63-year-old patient after the attempted removal of ICD electrodes, complicated by acute regurgitation of the tricuspid valve. The patient underwent urgent cardiac surgery, the electrode elements were removed, and the tricuspid valve was replaced with a biological prosthesis. After surgery, the patient required intensive, multidisciplinary treatment with mechanical ventilation, continuous renal replacement therapy, broad-spectrum empirical antibiotic therapy, parenteral nutrition, and blood product transfusion because of multiple organ failure. On the 14th day of hospitalisation, the clinical symptoms of septic shock were observed. The microbiological investigation was performed, and Lactobacillus casei was cultured from a dialysis catheter sample. Dedicated antimicrobials were administered, and the patient was discharged home in good overall condition.

CONCLUSIONS

The present case shows that the promoted use of probiotics must be cautiously administered to patients in severe conditions, especially when accompanied by reduced immune system efficiency symptoms.

An Unusual Case of Acute Cholecystitis Caused by Lactobacillus paracasei

Lactobacillus paracasei is a gram-positive rod commonly found in probiotic foods and is well known to promote healthy gastrointestinal tracts. However, there have been a few case reports that have found Lactobacillus paracasei to be the causative agent in complications such as endocarditis, meningitis, peritonitis, pancreatitis, and cholecystitis. We present the case of a 76-year-old woman who was admitted for decompensated heart failure. The patient also reported abdominal pain in the right upper quadrant. Ultrasound findings suggested cholelithiasis and a subsequent hepatobiliary iminodiacetic acid (HIDA) scan confirmed acute cholecystitis. This patient was not a good candidate for cholecystectomy because of the risk of cardiac complications. Hence, percutaneous cholecystostomy tube (PCT) placement was done, and the aspirate drained during the procedure was sent for pathology. This bile culture was positive for Lactobacillus paracasei and negative for any other kinds of bacteria. The incidence of Lactobacillus species-induced cholecystitis makes up only 0.08% to 0.2% of cases, which makes this an unusual case of acute cholecystitis caused by Lactobacillus paracasei. We will discuss several pathogenic aspects of Lactobacillus paracasei, such as its ability to generate biofilms, pore-forming toxins, drug transporters, and antibiotic susceptibility.

Metagenomic sequencing of human cardiac tissue reveals Microbial RNA which correlates with Toll-like receptor-associated inflammation in patients with heart disease

Cardiovascular disease (CVD) is strongly associated with chronic low-grade inflammation, involving activated Toll-like receptors and their downstream cellular machinery. Moreover, CVD and other related inflammatory conditions are associated with infiltration of bacteria and viruses originating from distant body sites. Thus, in this study we aimed to map the presence of microbes in the myocardium of patients with heart disease that we previously found to display upregulated Toll-like receptor signaling. We performed metagenomics analysis of atrial cardiac tissue from patients undergoing coronary artery bypass grafting (CABG) or aortic valve replacement (AVR) and compared with atrial cardiac tissue from organ donors. A total of 119 species of bacteria and seven species of virus were detected in the cardiac tissue. RNA expression of five bacterial species were increased in the patient group of which L. kefiranofaciens correlated positively with cardiac Toll-like receptor-associated inflammation. Interaction network analysis revealed four main gene set clusters involving cell growth and proliferation, Notch signaling, G protein signaling and cell communication in association with L. kefiranofaciens RNA expression. Taken together, intracardial expression of L. kefiranofaciens RNA correlates with pro-inflammatory markers in the diseased cardiac atrium and may have an effect on specific signaling processes important for cell growth, proliferation and cell communication.

A Case Report of Bacteremia Due to a Symptomatic and Rare Lactobacillus Rhamnosus Infected Splenic Hematoma and the Ultimate Treatment Model

We present the case of a 76-year-old male who presented to our hospital with a rare infection of Lactobacillus rhamnosus. The patient had a suspected urinary tract infection (UTI) secondary to a chronic indwelling catheter; however, when symptoms did not improve on standard therapy, blood cultures revealed the growth of L. rhamnosus. The patient was found via imaging to have a concurrent infectious splenic hematoma, and aspiration confirmed the presence of L. rhamnosus. The patient resided in an area nursing home and was a poor historian; however, it is conceivable that this infection was acquired via diet or from normal gut flora as the patient did not present on probiotic supplementation. In this case report, we present both pharmaceutical and interventional treatment strategies as well as a timeline of treatment for this rarely-seen infection.

The metabolites of lactic acid bacteria: classification, biosynthesis and modulation of gut microbiota

Lactic acid bacteria (LAB) are ubiquitous microorganisms that can colonize the intestine and participate in the physiological metabolism of the host. LAB can produce a variety of metabolites, including organic acids, bacteriocin, amino acids, exopolysaccharides and vitamins. These metabolites are the basis of LAB function and have a profound impact on host health. The intestine is colonized by a large number of gut microorganisms with high species diversity. Metabolites of LAB can keep the balance and stability of gut microbiota through aiding in the maintenance of the intestinal epithelial barrier, resisting to pathogens and regulating immune responses, which further influence the nutrition, metabolism and behavior of the host. In this review, we summarize the metabolites of LAB and their influence on the intestine. We also discuss the underlying regulatory mechanisms and emphasize the link between LAB and the human gut from the perspective of health promotion.

In vitro selection and characterization of probiotic properties in eight lactobacillus strains isolated from cocoa fermentation

Traditionally, probiotic microorganisms are isolated from human and animal intestinal microbiota. However, the demand for diversification of biofunctional products has driven the search for new sources of probiotic candidates, such as fermented foods and vegetables. The present study found that strains isolated from the fermentation of fine cocoa from southern Bahia have biotechnological potential for use as a probiotic, since they showed capacity for self-aggregation and co-aggregation, antimicrobial activity against intestinal pathogens and resistance to gastrointestinal transits. Scores of importance for each property were established in order to more accurately assess the probiotic potential of the strains. The tests carried out contemplate the criteria previously established for the selection of probiotic candidates.

Considerations for determining safety of probiotics: A USP perspective

A history of safe use is a backbone of safety assessments for many current probiotic species, however, there is no global harmonization regarding requirements for establishing probiotic safety for use in foods and supplements. As probiotic manufacturers are increasingly seeking to use new strains, novel species, and next-generation probiotics, justification based on a significant history of use may be challenged. There are efforts underway by a variety of stakeholders, including the United States Pharmacopeia (USP), to develop best practices guidelines for assessing the quality and safety of probiotics. A current initiative of the USP seeks to provide expert advice specific to safety considerations for probiotics. Toward this goal, this review provides a helpful summary guide to global regulatory guidelines. We question the suitability of traditional animal toxicology studies designed for testing chemicals for relevance in assessing probiotic safety. This includes discussion of the use of excessive dose levels, the length of repeated dose toxicity studies needed, and the most suitable animal species used in toxicology studies. In addition, the importance of proper manufacturing practices with regard to final product safety are also included. Thus, an outline of essential parameters of a comprehensive safety assessment for a probiotic are provided.

Gut microbiota: a new avenue to reveal pathological mechanisms of constipation

Constipation is very pervasive all over the world. It is a common multifactorial gastrointestinal disease, and its etiology and pathomechanism are not completely clear. Now, increasing evidence shows that intestinal flora is closely related to constipation. Intestinal flora is the largest microbiota in the human body and has powerful metabolic functions. Intestinal flora can produce a variety of metabolites, such as bile acids, short-chain fatty acids, tryptophan metabolites, and methane, which have important effects on intestinal motility and secretion. The host can also monitor the intestinal flora and regulate gut dysbacteriosis in constipation. To explore the relationship between intestinal flora and host, the combination of multiomics technology has become the powerful and effective method. Furthermore, the homeostasis restoration of intestinal flora also provides a new strategy for the treatment of constipation. This review aims to explore the interaction between intestinal flora and host in constipation, which contributes to disclose the pathogenesis of constipation and the development of novel drugs for the treatment of constipation from the perspective of intestinal flora. KEY POINTS: • This review highlights the regulation of gut microbiota on the intestinal motility and secretion of host. • The current review gives an insight into the role of the host on the recognition and regulation of intestinal ecology under constipation. • The article also introduces some novel methods of current gut microbiota research and gut microbiota-based constipation therapies.

Bacteraemia Caused by Probiotic Strains of Lacticaseibacillus rhamnosus—Case Studies Highlighting the Need for Careful Thought before Using Microbes for Health Benefits

Lactic acid bacteria belonging to Lactobacillus spp. and Lacticaseibacillus spp. are a natural part of fermented milk and other food products, probiotic supplements and human microbiota. They mainly belong to mucosal microflora, especially oral, vaginal and intestinal. Lacticaseibacillus spp. strains included in probiotics are generally characterised as safe microorganisms, and the species are concerned bacteria with very low pathogenic potential. However, infections caused by Lactobacillus spp. and Lacticaseibacillus spp., including bacteraemia and endocarditis, occur occasionally. The aim of the study was to present two cases of bacteraemia due to Lacticaseibacillus rhamnosus associated with the use of a probiotic product. It afflicted patients in intensive care units. The investigation was preliminarily based on clinical and microbiological recognition of the cases. The initial observation was laboratory confirmed with the application of pulsed-field gel electrophoresis (PFGE) results. Identical PFGE patterns were obtained for the evaluated strains and the strains derived from a commercially available probiotic that was administered to those patients. The increasing number of studies describing opportunistic infections due to probiotic strains of Lacticaseibacillus spp. should result in verifying the safety of probiotic formulations used in immunocompromised patients and forming detailed guidelines for the use of probiotics among patients from several risk groups.