Clinical and microbiological characteristics of bacteremia caused by Eggerthella, Paraeggerthella, and Eubacterium species at a university hospital in Taiwan from 2001 to 2010

Microbiota-Focused Dietary Approaches to Support Health: A Systematic Review

Diet affects the intestinal microbiota. Increasingly, research is linking the intestinal microbiota to various human health outcomes. Consumption of traditional prebiotics (inulin, fructo-oligosaccharides, and galacto-oligosaccharides) confers health benefits through substrate utilization by select intestinal microorganisms, namely Bifidobacterium and Lactobacilli spp. A similar but distinct concept focused on microorganisms to support human health is through direct consumption of certain live microorganisms recognized as probiotics, which classically include Lactobacilli or Bifidobacterium strains. With advances in sequencing technologies and culturing techniques, other novel functional intestinal microorganisms are being increasingly identified and studied to determine how they may underpin human health benefits. These novel microorganisms are targeted for enrichment within the autochthonous intestinal microbiota through dietary approaches and are also gaining interest as next-generation probiotics because of their purported beneficial properties. Thus, characterizing dietary approaches that nourish select microorganisms in situ is necessary to propel biotic-focused research forward. As such, we reviewed the literature to summarize findings on dietary approaches that nourish the human intestinal microbiota and benefit health to help fill the gap in knowledge on the connections between certain microorganisms, the metabolome, and host physiology. The overall objective of this systematic review was to summarize the impact of dietary interventions with the propensity to nourish certain intestinal bacteria, affect microbial metabolite concentrations, and support gastrointestinal, metabolic, and cognitive health in healthy adults. Findings from the 17 randomized controlled studies identified in this systematic review indicated that dietary interventions providing dietary fibers, phytonutrients, or unsaturated fatty acids differentially enriched Akkermansia, Bacteroides, Clostridium, Eubacterium, Faecalibacterium, Roseburia, and Ruminococcus species, with variable effects on microbial metabolites and subsequent associations with physiologic markers of gastrointestinal and metabolic health. These findings have implications for biotic-focused research on candidate prebiotic substrates as well as next-generation probiotics.

Lactobacillus plantarum TWK10 relieves loperamide-induced constipation in rats fed a high-fat diet via modulating enteric neurotransmitters, short-chain fatty acids and gut microbiota

Obesity and constipation can alter the intestinal microbiota composition, affecting intestinal barrier integrity, immune function, and metabolic processes. Numerous studies have suggested that Lactobacillus and Bifidobacterium could increase short-chain fatty acid (SCFA) production, thus improving the intestinal microbiota composition, mitigating obesity, and protecting the gastrointestinal tract. Therefore, in this study, we aimed to investigate the impact of Lactobacillus plantarum TWK10 (TWK10) on gut dysbiosis, obesity, and constipation induced by a high-fat diet and loperamide. Over a 5-week experimental period, rats were fed a high-fat diet and subsequently induced with gut dysbiosis and constipation using loperamide. Concurrently, rats were administered different doses of TWK10 or TWK10-fermented soy milk. Following administration of TWK10 or its fermented soy milk, the expression of adipocyte transcription factors such as PPARγ, C/EBPα, and C/EBPβ proteins and adipocyte size were significantly downregulated (p < 0.05). Regarding intestinal motility, compared to the high-fat diet-induced obesity and loperamide-induced constipation group (L), rats receiving TWK10 or its fermented soy milk exhibited regulation of gastrointestinal hormone levels such as gastrin (GT), somatostatin (Sst), calcitonin gene-related peptide (CGRP), and acetylcholinesterase (Ache) in serum. Additionally, there was a notable increase in the intestinal transit ratio, particularly in the 1X TWK10 group, in which it increased by 10.29% (p < 0.05). Furthermore, the consumption of TWK10 or its fermented soy milk significantly increased the number of goblet cells, as well as the thickness of the muscle and mucosal layers in the colon (p < 0.05). Analysis of SCFA content in fecal samples revealed a significant increase in SCFA concentrations, particularly acetic acid, following administration of both TWK10 and its fermented soy milk. Finally, TWK10 was found to modulate the composition of the intestinal microbiota and increase microbial diversity. In conclusion, TWK10 and its fermented soy milk effectively alleviated loperamide-induced constipation in rats fed a high-fat diet. These findings suggest that TWK10 and its fermented soy milk may potentially be functional foods for promoting intestinal health.

Clinical characteristics and antimicrobial susceptibility of Eggerthella lenta infection over a 5-year trend at a university hospital in Japan

Eggerthella lenta (E. lenta) is known to cause intra-abdominal and anaerobic bloodstream infections. However, clinical insights and information on antimicrobial susceptibility in E. lenta infections are limited. This study aimed to elucidate the clinical characteristics and antimicrobial susceptibility of E. lenta infections. Patients with E. lenta isolated from various specimens who presented at Aichi Medical University Hospital between January 2018 and December 2022 were included. Patient information was retrospectively collected from electronic medical records. Logistic regression analysis was conducted to identify risk factors for bloodstream infections. The antimicrobial susceptibility of various antimicrobial agents against isolated strains was investigated. During the study period, seventy cases were classified as infection cases. The median age of patients was 69 years (range: 15-100 years), and 48 (68.6%) were males. The most common site of infection was the lower digestive tract (54.3%). In 70.4% of cases, polymicrobial infections occurred. Community-acquired infection was a significant risk factor for bloodstream infection, with an odds ratio of 4.94 (95% confidence interval: 1.02-23.9). The 30-day mortality rate was 10.0%. Univariate analysis showed lower mortality in patients who underwent surgical intervention than in those who did not (42.9% vs 57.1%, p = 0.02). The proportion of minimal inhibitory concentrations (MICs) of ≥ 32 μg/mL for piperacillin-tazobactam was 6.3%. Additionally, the proportions of MICs of ≥ 8 μg/mL for imipenem and meropenem were 1.4% and 0%, respectively. E. lenta should be considered when blood cultures yield gram-positive rods in community-acquired intra-abdominal infections. Effective treatment involves both antimicrobial agents and surgical interventions.

Clinical and microbiological characteristics of Eggerthella lenta causing bacteremia

Eggerthella lenta is an obligate anaerobic, Gram-positive bacilli, belonging to the human microbiota of gastrointestinal and female reproductive tracts, oral cavity and prostate gland. In this article, we aim to describe clinical and microbiological characteristics of seven E. lenta strains causing bacteremia. We conducted a descriptive retrospective study including all E. lenta strains causing bacteremia, from February 2019 to August 2023 at the Basurto University Hospital. Seven patients were included in the study with a mean age of 72.7 years. Six patients presented risk factors associated with bacterial infections. All patients were admitted to the hospital because of suspicious of bloodstream infection associated with abdominal symptoms for intravenous antibiotic treatment. Four E. lenta isolates were resistant to penicillin, while all isolates presented high MICs to piperacillin/tazobactam and low MICs to amoxicillin/clavulanic acid. All patients recovered without no complications.

Paraclostridium tenue Causing an Anaerobic Brain Abscess Identified by Whole-Metagenome Sequencing: A Case Report

When treating anaerobic brain abscesses, healthcare professionals often face the difficulty of identifying the causal pathogens, necessitating empiric therapies with uncertain efficacy. We present the case of a 57-year-old woman who was admitted to our hospital with a fever and headache. Brain magnetic resonance imaging revealed a hemorrhagic lesion with wall enhancement at the left hemisphere on contrast-enhanced T1-weighted imaging. Cerebrospinal fluid examination showed pleocytosis (23 cells/μL), an elevated protein level (125 mg/dL), and decreased glucose level (51 mg/dL; blood glucose was 128 mg/dL). Intracerebral hemorrhage accompanied by a brain abscess was clinically suspected. The patient received empirical treatment with intravenous meropenem and vancomycin for 2 weeks. However, conventional bacterial culture tests failed to identify the pathogen. We then performed shotgun sequencing and ribosomal multilocus sequence typing, which identified Paraclostridium tenue. Based on this finding, we de-escalated to benzylpenicillin potassium for 4 weeks, leading to a 2.5-year remission of the anaerobic brain abscess. Therefore, Paraclostridium can be a causative pathogen for brain abscesses. Furthermore, whole-metagenome sequencing is a promising method for detecting rare pathogens that are not identifiable by conventional bacterial culture tests. This approach enables more targeted treatment and contributes to achieving long-term remission in clinical settings.

Eubacterium callanderi bacteremia: A case report

Eubacterium species are a group of obligated anaerobic gram-positive bacilli that are recognized as commensals of the gastrointestinal tract flora. Cases of bacteremia mediated by Eubacterium are rare. This report describes a case of bacteremia caused by Eubacterium callanderi in an 82-year-old female with a history of a cecal perforation secondary to an obstructing sigmoid stricture. The results showed the utility of using whole genome sequencing to identify the causative agent and underlined the significance to identify anaerobic organisms in diagnostic microbiology practice and to perform antimicrobial susceptibility testing to guide therapy and enhance patient outcomes.

Eubacterium bacteremia - a retrospective observational study of a seldom found anaerobic pathogen

BACKGROUND

Human infections due to Eubacterium are rare and knowledge of the condition is limited. This study aimed to describe clinical characteristics and outcome in patients with Eubacterium bacteremia.

METHODS

Episodes of Eubacterium bacteremia were identified through the clinical microbiology laboratory in Lund, Sweden. Medical records were retrospectively reviewed. Blood isolates of Eubacterium were collected and antibiotic susceptibility testing was performed with agar dilution.

RESULTS

Seventeen patients with Eubacterium bacteremia were identified of whom six had monomicrobial bacteremia. The incidence was 1.7 cases of Eubacterium bacteremia per million inhabitants and year. The median age was 67 years (interquartile range 63-79 years), and six patients had some form of malignancy. Most of the patients an abdominal focus of infection and the 30-day mortality was low (n = 1).

CONCLUSIONS

Invasive infections with Eubacterium have a low incidence. The condition has a low mortality and an abdominal focus of infection, and malignancy, is common.

First periprosthetic hip infection caused by Eggerthella lenta

Periprosthetic joint infection (PJI) caused by anaerobic, Gram-positive bacilli is rare. We present here a case of an 83-year-old female patient who was admitted to our tertiary referral arthroplasty center to treat a complex PJI of her right hip joint after multiple failed surgeries. External and intraoperative cultures reveald growth of Eggerthella lenta (E. lenta). Microbiological identification was fast but in a very few samples. A successful management, comprising of radical debridement with one-stage exchange and an antibiotic treatment with multiple antibiotics, has been achieved at 24-month follow-up. To the best of our knowledge, we have provided the first case study of a hip PJI caused by E. lenta successfully treated with one-stage exchange and an adequate antibiotic treatment.

Antimicrobial Susceptibility Profile of Rare Anaerobic Bacteria

Anaerobes play an important role in clinically relevant infections and resistance is increasing worldwide. We tested 120 rare anaerobic isolates belonging to 16 genera for antimicrobial resistance using the agar dilution method and compared those results to the time-saving E-test method. The susceptibility data for 12 antimicrobial substances (benzylpenicillin, ampicillin/sulbactam, piperacillin/tazobactam, imipenem, meropenem, cefoxitin, metronidazole, moxifloxacin, clindamycin, doxycycline, tigecycline, eravacycline) were collected. Susceptibility testing showed low resistance to β-lactam/β-lactamase inhibitor combinations and no resistance to carbapenems and tigecycline. We observed moderate to high rates of resistance to moxifloxacin and clindamycin which differed depending on the methodology used. The essential and categorical agreement was over 90% for ampicillin/sulbactam, meropenem, moxifloxacin, and tigecycline. For metronidazole and clindamycin, the essential agreement was below 90% but the categorical agreement was near or above 90%. Penicillin presented with the lowest categorical agreement of 86.7% and a very high very major error rate of 13.3%. The resistance rates reported in this study are concerning and show the importance of routine susceptibility testing. Further investigations are necessary to determine the reason for high error rates and how to improve susceptibility testing of fastidious anaerobes.

Expanding the genetic engineering toolbox for the metabolically flexible acetogen Eubacterium limosum

Acetogenic bacteria are an increasingly popular choice for producing fuels and chemicals from single carbon (C1) substrates. Eubacterium limosum is a promising acetogen with several native advantages, including the ability to catabolize a wide repertoire of C1 feedstocks and the ability to grow well on agar plates. However, despite its promise as a strain for synthetic biology and metabolic engineering, there are insufficient engineering tools and molecular biology knowledge to leverage its native strengths for these applications. To capitalize on the natural advantages of this organism, here we extended its limited engineering toolbox. We evaluated the copy number of three common plasmid origins of replication and devised a method of controlling copy number and heterologous gene expression level by modulating antibiotic concentration. We further quantitatively assessed the strength and regulatory tightness of a panel of promoters, developing a series of well-characterized vectors for gene expression at varying levels. In addition, we developed a black/white colorimetric genetic reporter assay and leveraged the high oxygen tolerance of E. limosum to develop a simple and rapid transformation protocol that enables benchtop transformation. Finally, we developed two new antibiotic selection markers—doubling the number available for this organism. These developments will enable enhanced metabolic engineering and synthetic biology work with E. limosum.

Immunometabolic Analysis of Mobiluncus mulieris and Eggerthella sp. Reveals Novel Insights Into Their Pathogenic Contributions to the Hallmarks of Bacterial Vaginosis

The cervicovaginal microbiome plays an important role in protecting women from dysbiosis and infection caused by pathogenic microorganisms. In healthy reproductive-age women the cervicovaginal microbiome is predominantly colonized by protective Lactobacillus spp. The loss of these protective bacteria leads to colonization of the cervicovaginal microenvironment by pathogenic microorganisms resulting in dysbiosis and bacterial vaginosis (BV). Mobiluncus mulieris and Eggerthella sp. are two of the many anaerobes that can contribute to BV, a condition associated with multiple adverse obstetric and gynecological outcomes. M. mulieris has been linked to high Nugent scores (relating to BV morphotypes) and preterm birth (PTB), whilst some bacterial members of the Eggerthellaceae family are highly prevalent in BV, and identified in ~85-95% of cases. The functional impact of M. mulieris and Eggerthella sp. in BV is still poorly understood. To determine the individual immunometabolic contributions of Eggerthella sp. and M. mulieris within the cervicovaginal microenvironment, we utilized our well-characterized human three-dimensional (3-D) cervical epithelial cell model in combination with multiplex immunoassays and global untargeted metabolomics approaches to identify key immune mediators and metabolites related to M. mulieris and Eggerthella sp. infections. We found that infection with M. mulieris significantly elevated multiple proinflammatory markers (IL-6, IL-8, TNF-α and MCP-1) and altered metabolites related to energy metabolism (nicotinamide and succinate) and oxidative stress (cysteinylglycine, cysteinylglycine disulfide and 2-hydroxygluatrate). Eggerthella sp. infection significantly elevated multiple sphingolipids and glycerolipids related to epithelial barrier function, and biogenic amines (putrescine and cadaverine) associated with elevated vaginal pH, vaginal amine odor and vaginal discharge. Our study elucidated that M. mulieris elevated multiple proinflammatory markers relating to PTB and STI acquisition, as well as altered energy metabolism and oxidative stress, whilst Eggerthella sp. upregulated multiple biogenic amines associated with the clinical diagnostic criteria of BV. Future studies are needed to evaluate how these bacteria interact with other BV-associated bacteria within the cervicovaginal microenvironment.

Modifying the Microbiome as a Potential Mechanism of Photobiomodulation: A Case Report

Objective: The objective of this case study was to elucidate the effect of photobiomodulation (PBM) on the microbiome. Background: The gut microbiome has been identified as a key component of health, with gut dysbiosis, characterized by decreased microbial diversity and an altered microbial composition, being recognized as instrumental in many diseases and disorders. Previous research has suggested that the gut microbiome can be favorably altered in animal models using PBM. Materials and methods: The participant had their microbiome tested on nine occasions, three times before any treatment, three times after radiotherapy and commencement of immunotherapy for breast cancer, and three times after PBM treatment. The PBM treatment consisted of infrared laser treatment (904 nm; 700 Hz pulse frequency, 861.3 total joules) to the abdomen three times per week for 11 weeks. Results: The microbiome of the participant showed significant changes in diversity after PBM treatment, but not after cancer therapy, with an increase in the number of known beneficial bacteria (Akkermansia, Faecalibacterium, and Roseburia) and decrease in the number of potentially pathogenic genera. Conclusions: The results suggested the possibility that PBM may alter the microbiome and thus it represents a therapeutic avenue for chronic diseases with otherwise limited treatment options.

Eggerthella lenta bacteremia successfully treated with ceftizoxime: case report and review of the literature

Eggerthella lenta is a normal human microflora that is anaerobic, non-sporulating, and Gram positive. However, an increasing number of studies have shown that it could also be an important pathogen for humans, even causing life-threatening infection under certain conditions. However, understanding its pathogenic mechanism and treatment options still need to be improved; more clinical data are needed to explore it further. In this article, we report a case of ceftizoxime-cured E. lenta bacteremia and review the recent literature to provide more clinical data for the diagnosis of E. lenta bacteremia. Our report suggests that the frequency of E. lenta bacteremia is increased in patients with hematologic or solid organ cancer, diabetes mellitus and also in those with appendicitis.

Eggerthella lenta Bacteremia in a Middle-Aged Healthy Man with Acute Hepatic Abscess: Case Report and Literature Review, 1970-2020

Eggerthella lenta (E. lenta) is a rare but significant human emerging pathogen. Infections caused by it are rare and little-known, both on clinical and therapeutical aspects, in spite of new emergence of bacteria isolation and identification techniques. In this article, we report a case involving a previously healthy 52-year-old man suffering from a newly diagnosed hepatic abscess who developed E. lenta bacteremia, which was treated successfully using empirical therapy with ertapenem and teicoplanin. To the best of our knowledge, this is the first documented report of E. lenta bacteremia related specifically to liver abscess. Cases related to this bacterial species are infrequent and sporadic; thus, we reviewed English literature on E. lenta infection in PubMed/MEDLINE in the last 50 years. A total of 31 sporadic cases were identified. The majority of patients were male (71%), had an average age of 54.3 years and presented predisposing conditions, such as digestive system trouble (45.2%), immunocompromised state (25.8%) or risk factors (22.6%). Two of the cases had more than one predisposing factors. Fever was common (93.5%). Average days to diagnosis of them were 6.8 days. MALDI-TOF MS is emerging as a fast and useful tool in the identification of it. Teicoplanin, vancomycin, amoxicillin-clavulanate, metronidazole, clindamycin, cefoxitin, chloramphenicol, and carbapenems appear to be the most used antibiotic treatment options. The purpose of this review is to increase awareness about the clinical infections caused by E. lenta.

Antimicrobial susceptibility testing of Eggerthella lenta blood culture isolates at a university hospital in Belgium from 2004 to 2018

OBJECTIVES

Eggerthella lenta is a Gram-positive anaerobic bacillus that is an important cause of bloodstream infections. This study aims to test the susceptibility of Eggerthella lenta blood culture isolates to commonly used antibiotics for the empirical treatment of anaerobic infections.

METHODS

In total, 49 positive blood cultures for Eggerthella lenta were retrospectively included from patients hospitalised at the Universitair Ziekenhuis Brussel, Belgium, between 2004 and 2018. Identification was done by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Antimicrobial susceptibility testing was performed using the reference agar dilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines with Brucella agar supplemented with 5 μg/mL hemin, 1 μg/mL vitamin K1 and 5% laked sheep blood. The minimal inhibitory concentrations were interpreted using the EUCAST breakpoints. Clinical characteristics were collected by reviewing the patient's medical records.

RESULTS

All isolates were susceptible to amoxicillin-clavulanate, metronidazole and meropenem. Eighty-eight % of them were susceptible to clindamycin and 94% (20% S, 74% I) were susceptible to piperacillin-tazobactam. The mean age of the patients was 64 (±20) and they showed a 30-day mortality of 27%. The source of infection was in 65.3% of the cases abdominal, 20.4% were sacral pressure ulcers and 14.3% were unknown causes. While all isolates were fully susceptible at standard dosing regimen to amoxicillin-clavulanate, most were only susceptible at increased exposure or resistant to piperacillin-tazobactam.

CONCLUSIONS

Our results suggest to be careful with the use of piperacillin-tazobactam and clindamycin in the empirical treatment of Eggerthella lenta infections.

Antimicrobial Susceptibility Patterns and Wild-Type MIC Distributions of Anaerobic Bacteria at a German University Hospital: A Five-Year Retrospective Study (2015-2019)

Local antimicrobial susceptibility surveys are crucial for optimal empirical therapy guidelines and for aiding in antibiotic stewardship and treatment decisions. For many laboratories, a comprehensive overview of local antimicrobial susceptibility patterns of anaerobic bacteria is still lacking due to the long incubation time and effort involved. The present study investigates the antimicrobial susceptibility patterns and related clinical and demographic data of 2856 clinical isolates of anaerobic bacteria that were submitted for analysis to the Institute for Medical Microbiology and Hygiene of the Freiburg University Medical Center (a tertiary university medical center in Southern Germany) between 2015 and 2019. Antimicrobial susceptibility testing has been carried out according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guideline. Minimum inhibitory concentration (MIC)₅₀ and MIC₉₀ for penicillin, metronidazole, moxifloxacin, and clindamycin were established for Gram-positive anaerobes and for ampicillin-sulbactam, meropenem, metronidazole, moxifloxacin, and clindamycin for Gram-negative anaerobes. The distribution of MIC-values for various antibiotics against anaerobic bacteria was also established, especially for those having no specific breakpoints according to EUCAST guidelines. Most clinically relevant anaerobic bacteria originated from general surgery, neurological, and orthopedic wards. A high proportion of isolates were resistant to moxifloxacin and clindamycin indicating the importance of their susceptibility testing before administration. Based on our study metronidazole and other β-lactam/β-lactamase inhibitor combinations such as ampicillin-sulbactam remain suitable for empirical treatment of infections with anaerobic bacteria.

Performance and Application of 16S rRNA Gene Cycle Sequencing for Routine Identification of Bacteria in the Clinical Microbiology Laboratory

This review provides a state-of-the-art description of the performance of Sanger cycle sequencing of the 16S rRNA gene for routine identification of bacteria in the clinical microbiology laboratory. A detailed description of the technology and current methodology is outlined with a major focus on proper data analyses and interpretation of sequences. The remainder of the article is focused on a comprehensive evaluation of the application of this method for identification of bacterial pathogens based on analyses of 16S multialignment sequences. In particular, the existing limitations of similarity within 16S for genus- and species-level differentiation of clinically relevant pathogens and the lack of sequence data currently available in public databases is highlighted. A multiyear experience is described of a large regional clinical microbiology service with direct 16S broad-range PCR followed by cycle sequencing for direct detection of pathogens in appropriate clinical samples. The ability of proteomics (matrix-assisted desorption ionization-time of flight) versus 16S sequencing for bacterial identification and genotyping is compared. Finally, the potential for whole-genome analysis by next-generation sequencing (NGS) to replace 16S sequencing for routine diagnostic use is presented for several applications, including the barriers that must be overcome to fully implement newer genomic methods in clinical microbiology. A future challenge for large clinical, reference, and research laboratories, as well as for industry, will be the translation of vast amounts of accrued NGS microbial data into convenient algorithm testing schemes for various applications (i.e., microbial identification, genotyping, and metagenomics and microbiome analyses) so that clinically relevant information can be reported to physicians in a format that is understood and actionable. These challenges will not be faced by clinical microbiologists alone but by every scientist involved in a domain where natural diversity of genes and gene sequences plays a critical role in disease, health, pathogenicity, epidemiology, and other aspects of life-forms. Overcoming these challenges will require global multidisciplinary efforts across fields that do not normally interact with the clinical arena to make vast amounts of sequencing data clinically interpretable and actionable at the bedside.

Eggerthella lenta bloodstream infections: two cases and review of the literature

Eggerthella lenta is an emerging and uncommon human pathogen that has been under recognized due to the limitations of phenotypic identification. Here we describe two cases of bacteremia caused by E. lenta and summarize the results of antimicrobial susceptibility testing according to some previous literatures, which illustrate the importance of identification and treatment of unusual organisms. The most reliable antibiotic treatment options to E. lenta appear to be metronidazole, amoxicillin-clavulanate, carbapenems, vancomycin, cefoxitin, chloramphenicol and clindamycin.

Eggerthella lenta Bloodstream Infections Are Associated With Increased Mortality Following Empiric Piperacillin-Tazobactam (TZP) Monotherapy: A Population-based Cohort Study

Background

Eggerthella lenta is a anaerobic gram-positive bacilli associated with polymicrobial intraabdominal infections. Recently, E. lenta was recognized as an important cause of anaerobic bloodstream infections (BSIs) associated with high mortality. Eggerthella lenta has been reported to have high minimal inhibitory concentrations (MICs) to piperacillin-tazobactam (TZP), a broad-spectrum antibiotic with anaerobic coverage commonly used in multiple centers for empiric treatment of abdominal sepsis.

Methods

We describe a retrospective population-based analysis of invasive E. lenta infections from 2009 through 2015. A logistic regression analysis for 30-day mortality risk factors was conducted.

Results

We identified 107 E. lenta infections, 95 (89%) were BSIs, 11 (10%) skin and soft tissue infections, and 1 intraabdominal abscess. Polymicrobial infections were found in 40%; 72% of isolates were from a gastrointestinal source, most commonly appendicitis (33%) of which two-thirds were perforated. TZP MIC50 and MIC90 for E. lenta isolates were 32 μg/mL and 64 μg/mL, respectively. The overall 30-day mortality for BSI was 23% and was independently associated with empiric TZP monotherapy (odds ratio [OR], 4.4; 95% confidence interval [CI], 1.2-16; P = .02) and intensive care unit stay (OR, 6.2; 95% CI, 1.4-27.3; P = .01). Thirty-day mortality rates were significantly influenced by the use of different TZP MIC breakpoints.

Conclusions

Our results demonstrate the increased recognition of E. lenta as an anaerobic opportunistic pathogen and highlight the need for improved empiric antimicrobial guidelines and TZP MIC breakpoints with better correlation to clinical outcomes to guide appropriate management of invasive E. lenta infections.

Antibiotic resistance genes in the Actinobacteria phylum

The Actinobacteria phylum is one of the oldest bacterial phyla that have a significant role in medicine and biotechnology. There are a lot of genera in this phylum that are causing various types of infections in humans, animals, and plants. As well as antimicrobial agents that are used in medicine for infections treatment or prevention of infections, they have been discovered of various genera in this phylum. To date, resistance to antibiotics is rising in different regions of the world and this is a global health threat. The main purpose of this review is the molecular evolution of antibiotic resistance in the Actinobacteria phylum.

Noncontiguous finished genome sequence and description of Raoultibacter massiliensis gen. nov., sp. nov. and Raoultibacter timonensis sp. nov, two new bacterial species isolated from the human gut

As part of the culturomics project aiming at describing the human microbiota, we report in this study the description of the new bacterial genus Raoultibacter gen. nov. that includes two new species, that is, R. massiliensis sp. nov. and R. timonensis sp. nov. The R. massiliensis type strain Marseille-P2849T was isolated from the fecal specimen of a healthy 19-year-old Saudi Bedouin, while R. timonensis type strain Marseille-P3277T was isolated from the feces of an 11-year-old pygmy female living in Congo. Strain Marseille-P2849T exhibited 91.4% 16S rRNA sequence similarity with Gordonibacter urolithinfaciens, its phylogenetic closest neighbor with standing in nomenclature. As well, strain Marseille-P3277T exhibited 97.96% 16S rRNA similarity with strain Marseille-P2849T . Both strains were Gram-positive, motile, nonspore-forming rod and form transparent microcolonies on blood agar in both anaerobic and microaerophilic atmospheres. The genome sizes of strain Marseille-P2849T and strain Marseille-P3277T were 3,657,161 bp and 4,000,215 bp, respectively. Using a taxono-genomic approach combining the phenotypic, biochemical, and genomic characteristics, we propose the genus Raoultibacter gen. nov., which contains strains Marseille-P2849T (= CSUR P2849T , = DSM 103407T ) and Marseille-P3277T (=CCUG 70680T , =CSUR P3277T ) as type strains of the species R. massiliensis sp. nov., and R. timonensis sp. nov., respectively.

Postpartum endometritis and obstetrical sepsis associated with Eggerthella lenta. Case report and review of the literature

Sepsis, associated with Eggerthella lenta is rarely reported, despite current possibilities for microorganisms isolation and identification. About 100 cases of bacteriemia associated with this pathogen have been reported so far. Postpartum infectious complications are mostly associated with bacterial inhabitants of gastrointestinal tract and vagina, including obligatory anaerobes. This case report highlights E. lenta-associated severe endometritis complicated by abdominal sepsis in a young healthy woman, and the challenges of antibacterial therapy.

Antimicrobial Susceptibility Patterns of Anaerobic Bacterial Clinical Isolates From 2014 to 2016, Including Recently Named or Renamed Species

BACKGROUND

Anaerobic bacterial resistance trends may vary across regions or institutions. Regional susceptibility patterns are pivotal in the empirical treatment of anaerobic infections. We determined the antimicrobial resistance patterns of clinically important anaerobic bacteria, including recently named or renamed anaerobes.

METHODS

A total of 521 non-duplicated clinical isolates of anaerobic bacteria were collected from a tertiary-care hospital in Korea between 2014 and 2016. Anaerobes were isolated from blood, body fluids, and abscess specimens. Each isolate was identified by conventional methods and by Bruker biotyper mass spectrometry (Bruker Daltonics, Leipzig, Germany) or VITEK matrix-assisted laser desorption ionization time-of-flight mass spectrometry (bioMérieux, Marcy-l'Étoile, France). Antimicrobial susceptibility was tested using the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, tetracycline, and metronidazole.

RESULTS

Most Bacteroides fragilis isolates were susceptible to piperacillin-tazobactam, imipenem, and meropenem. The non-fragilis Bacteroides group (including B. intestinalis, B. nordii, B. pyogenes, B. stercoris, B. salyersiae, and B. cellulosilyticus) was resistant to meropenem (14%) and cefotetan (71%), and Parabacteroides distasonis was resistant to imipenem (11%) and cefotetan (95%). Overall, the Prevotella and Fusobacterium isolates were more susceptible to antimicrobial agents than the B. fragilis group isolates. Anaerobic gram-positive cocci exhibited various resistance rates to tetracycline (6-86%). Clostridioides difficile was highly resistant to penicillin, cefoxitin, imipenem, clindamycin, and moxifloxacin.

CONCLUSIONS

Piperacillin-tazobactam, cefoxitin, and carbapenems are highly active β-lactam agents against most anaerobes, including recently named or renamed species.

Bacterial Anaerobic Synthesis Gas (Syngas) and CO2+H2 Fermentation

Anaerobic bacterial gas fermentation gains broad interest in various scientific, social, and industrial fields. This microbial process is carried out by a specific group of bacterial strains called acetogens. All these strains employ the Wood-Ljungdahl pathway but they belong to different taxonomic groups. Here we provide an overview of the metabolism of acetogens and naturally occurring products. Characteristics of 61 strains were summarized and selected acetogens described in detail. Acetobacterium woodii, Clostridium ljungdahlii, and Moorella thermoacetica serve as model organisms. Results of approaches such as genome-scale modeling, proteomics, and transcriptomics are discussed. Metabolic engineering of acetogens can be used to expand the product portfolio to platform chemicals and to study different aspects of cell physiology. Moreover, the fermentation of gases requires specific reactor configurations and the development of the respective technology, which can be used for an industrial application. Even though the overall process will have a positive effect on climate, since waste and greenhouse gases could be converted into commodity chemicals, some legislative barriers exist, which hamper successful exploitation of this technology.

Eggerthella lenta bacteremia in solid tumor cancer patients: Pathogen or witness of frailty?

Eggerthella lenta is increasingly found in patients with severe comorbidities. Because oncologic patients are exposed to emerging pathogens, we aimed to describe the factors associated with E. lenta bacteremia in this immunosuppressed population. Oncology patients with blood cultures positive for E. lenta were retrospectively recorded from 2009 to 2015. Socio-demographic and medical/biological data as well as potential risk factors and mortality were recorded and analyzed. Twenty-three patients were included. Gastro intestinal (GI) and gynecological cancers were reported in 12/23 (52%) and 7/23 cases (30%), respectively. Eleven/23 patients (48%) had metastatics lesions and 6/23 (26%) had peritoneal carcinomatosis. No associated tissue infection was found in 14/23 cases (61%). Blood cultures yielded at least one other species in addition to E. lenta in 10/23 cases (43%). Mortality associated with E. lenta bacteremia was 22% (5/23). E. lenta bacteremia often occurred in patients with advanced cancer disease without documented infection. In most of the cases, intestinal obstruction and/or isolated fever were the only recorded symptoms. In these cases, the damages of intestinal barrier induced by the cancer and/or its specific treatments may be the cause of bacterial translocation.

Microbiological diagnosis of Eggerthella lenta blood culture isolates in a Swedish tertiary hospital: Rapid identification and antimicrobial susceptibility profile

Eggerthella lenta is a Gram-positive anaerobic bacillus. Improved diagnostics and increased awareness of rare pathogens have revealed its potential to cause serious invasive infections. In this study, 18 clinical E. lenta isolates derived from positive blood cultures were included. Underlying problems of the patients were in the majority of cases related to the gastrointestinal tract. The performance of two MALDI-TOF MS systems, i.e. Bruker and Vitek MS, in identification of E. lenta was analyzed. In addition, the minimal inhibitory concentrations for clinically relevant antimicrobial agents were determined by routine procedures using E-test. 17 of the 18 E. lenta isolates investigated in this study were correctly identified to species level by the Bruker MS system, while the Vitek MS system identified all 18 isolates. Antimicrobial sensitivity towards the tested agents was in general good. However, high resistance rates were observed for penicillin G and piperacillin-tazobactam based on EUCAST breakpoints.

Clinical and microbiological characteristics of Eggerthella lenta bacteremia

Eggerthella lenta is an emerging pathogen that has been underrecognized due to historical difficulties with phenotypic identification. Until now, its pathogenicity, antimicrobial susceptibility profile, and optimal treatment have been poorly characterized. In this article, we report the largest cohort of patients with E. lenta bacteremia to date and describe in detail their clinical features, microbiologic characteristics, treatment, and outcomes. We identified 33 patients; the median age was 68 years, and there was no gender predominance. Twenty-seven patients (82%) had serious intra-abdominal pathology, often requiring a medical procedure. Of those who received antibiotics (28/33, 85%), the median duration of treatment was 21.5 days. Mortality from all causes was 6% at 7 days, 12% at 30 days, and 33% at 1 year. Of 26 isolates available for further testing, all were identified as E. lenta by both commercially available matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, and none were found to harbor a vanA or vanB gene. Of 23 isolates which underwent susceptibility testing, all were susceptible to amoxicillin-clavulanate, cefoxitin, metronidazole, piperacillin-tazobactam, ertapenem, and meropenem, 91% were susceptible to clindamycin, 74% were susceptible to moxifloxacin, and 39% were susceptible to penicillin.

Bacteremia caused by Eggerthella lenta in an elderly man with a gastrointestinal malignancy: A case report

Eggerthella lenta is an anaerobic, Gram-positive bacillus commonly found in the human digestive tract. Occasionally, it can cause life-threatening infections. Bacteremia due to this organism is always clinically significant and is associated with gastrointestinal diseases and states of immune suppression. The authors report a case involving an elderly man with a newly diagnosed gastrointestinal malignancy who developed bacteremia caused by E lenta, treated successfully using empirical therapy with vancomycin and piperacillin-tazobactam, followed by directed therapy with metronidazole once the identity and antibiotic susceptibility of the organism was established. The present case reinforces the connection between E lenta bacteremia with gastrointestinal malignancy and highlights the importance of searching for a source of bacteremia due to this organism.

High-throughput DNA microarray detection of pathogenic bacteria in shallow well groundwater in the Kathmandu Valley, Nepal

Because of heavy dependence on groundwater for drinking water and other domestic use, microbial contamination of groundwater is a serious problem in the Kathmandu Valley, Nepal. This study investigated comprehensively the occurrence of pathogenic bacteria in shallow well groundwater in the Kathmandu Valley by applying DNA microarray analysis targeting 941 pathogenic bacterial species/groups. Water quality measurements found significant coliform (fecal) contamination in 10 of the 11 investigated groundwater samples and significant nitrogen contamination in some samples. The results of DNA microarray analysis revealed the presence of 1-37 pathogen species/groups, including 1-27 biosafety level 2 ones, in 9 of the 11 groundwater samples. While the detected pathogens included several feces- and animal-related ones, those belonging to Legionella and Arthrobacter, which were considered not to be directly associated with feces, were detected prevalently. This study could provide a rough picture of overall pathogenic bacterial contamination in the Kathmandu Valley, and demonstrated the usefulness of DNA microarray analysis as a comprehensive screening tool of a wide variety of pathogenic bacteria.

Clinical characteristics and outcomes of patients with pleural infections due to Stenotrophomonas maltophilia at a medical center in Taiwan, 2004-2012

Stenotrophomonas maltophilia can cause various clinical diseases; however, pleural infections due to S. maltophilia are rare. We evaluated the clinical characteristics and outcomes of patients with pleural infections (complicated parapneumonic effusion or empyema) due to S. maltophilia who were treated at a medical center in Taiwan from 2004 to 2012. During the study period, 40 patients were treated for pleural infections due to S. maltophilia. The incidence of S. maltophilia pleural infections ranged from 2.66 per 1,000,000 patient-days in 2009 to 12.44 per 1,000,000 patient-days in 2011. Most of the patients with S. maltophilia pleural infections were immunocompromised male adults and all of the infections were acquired in healthcare settings. The majority of patients had polymicrobial pleural infections (n = 31, 77.5 %) and the most common pathogen was Pseudomonas aeruginosa (n = 12). The causes of pleural infections due to S. maltophilia were pneumonia due to S. maltophilia in two patients (5 %), post-surgical/tube thoracostomy in 26 (65 %) patients, and fistula (bronchopleural, esophagopleural and biliopleural) in 12 (30 %) patients. The 14-day and 30-day mortality rates were 32.5 % and 42.5 %, respectively. Pleural infections due to S. maltophilia are most commonly the result of surgical procedures, thoracostomy, and underlying fistulas. These infections are associated with a high mortality rate, especially among immunocompromised patients.

Eggerthella lenta bacteremia complicated by spondylodiscitis, psoas abscess, and meningitis

Eggerthella lenta bacteremia is uncommon and generally associated with abdominal sepsis. The organism and its clinical significance have not been well characterized due to historical difficulties with identification. We report a case of severe infection in a paraplegic man complicated by psoas abscess, osteomyelitis, and meningitis and discuss treatment challenges.

Disseminated Infection Caused by Eggerthella lenta in a Previously Healthy Young Man: A Case Report

Anaerobic bacteria are the predominant normal flora of the mucous membranes which may cause life-threatening disseminated infections and are often difficult to culture from infected sites. Eggerthella (previously known as Eubacteria species) is an anaerobic, nonsporulating, nonmotile, Gram-positive rod that is found in the human colon and feces and has been isolated from various other clinical specimens. We report a case of complicated disseminated anaerobic bacterial infection with Eggerthella lenta in a healthy immunocompetent man causing multiple brain abscesses, liver abscesses, necrotizing pneumonia, and osteomyelitis of the left radial bone. He was successfully treated with empiric penicillin G and metronidazole.