Enterococcus cecorum aortic valve endocarditis

A rare case of invasive Enterococcus cecorum infection and related diagnostic difficulties

Key Clinical Message

This report presents a rare case of invasive infection caused by Enterococcus cecorum. There are no specific guidelines regarding antibiotic therapy for this infection. Based on this case, it can be concluded that linezolid demonstrates in vivo activity against Enterococcus cecorum and can be successfully used in therapy.

Abstract

Enterococcus cecorum is an extremely rare pathogen in humans. Since 1984, when the microorganism was first described, only a dozen cases of invasive infections in humans have been reported in the literature. The diagnostic pathway may involve difficulties in correctly identifying this microorganism. Based on the case described, it can be thought that Enterococcus cecorum is a more challenging bacterium than the much more common Enterococcus faecium or Enterococcus faecalis. The described case underscores the importance of medical vigilance in clinical practice. It seems that due to increasingly advanced techniques in molecular biology, we will more frequently detect pathogens that were previously encountered only sporadically. Since not every center has access to modern and advanced microbiological diagnostic methods, publications that practically combine classical microbiological diagnostic methods with those less accessible but more modern are exceptionally valuable. In the case described, it is also worth noting that classical methods still play a significant and crucial role in conducting microbiological diagnostics. In the era of rapid diagnostic tool development, it is important to emphasize the necessity of combining different methods rather than replacing one with another.

Non-faecium non-faecalis enterococci: a review of clinical manifestations, virulence factors, and antimicrobial resistance

SUMMARYEnterococci are a diverse group of Gram-positive bacteria that are typically found as commensals in humans, animals, and the environment. Occasionally, they may cause clinically relevant diseases such as endocarditis, septicemia, urinary tract infections, and wound infections. The majority of clinical infections in humans are caused by two species: Enterococcus faecium and Enterococcus faecalis. However, there is an increasing number of clinical infections caused by non-faecium non-faecalis (NFF) enterococci. Although NFF enterococcal species are often overlooked, studies have shown that they may harbor antimicrobial resistance (AMR) genes and virulence factors that are found in E. faecium and E. faecalis. In this review, we present an overview of the NFF enterococci with a particular focus on human clinical manifestations, epidemiology, virulence genes, and AMR genes.

Antibiotic Resistance among Gastrointestinal Bacteria in Broilers: A Review Focused on Enterococcus spp. and Escherichia coli

Chickens can acquire bacteria at different stages, and bacterial diversity can occur due to production practices, diet, and environment. The changes in consumer trends have led to increased animal production, and chicken meat is one of the most consumed meats. To ensure high levels of production, antimicrobials have been used in livestock for therapeutic purposes, disease prevention, and growth promotion, contributing to the development of antimicrobial resistance across the resident microbiota. Enterococcus spp. and Escherichia coli are normal inhabitants of the gastrointestinal microbiota of chickens that can develop strains capable of causing a wide range of diseases, i.e., opportunistic pathogens. Enterococcus spp. isolated from broilers have shown resistance to at least seven classes of antibiotics, while E. coli have shown resistance to at least four. Furthermore, some clonal lineages, such as ST16, ST194, and ST195 in Enterococcus spp. and ST117 in E. coli, have been identified in humans and animals. These data suggest that consuming contaminated animal-source food, direct contact with animals, or environmental exposure can lead to the transmission of antimicrobial-resistant bacteria. Therefore, this review focused on Enterococcus spp. and E. coli from the broiler industry to better understand how antibiotic-resistant strains have emerged, which antibiotic-resistant genes are most common, what clonal lineages are shared between broilers and humans, and their impact through a One Health perspective.

Purpura fulminans due to Enterococcus cecorum in an asplenic patient

Enterococcus cecorum was initially isolated from the intestine of poultry and is an uncommon cause of human infection. We report here what we believe to be the first case of overwhelming post-splenectomy infection (OPSI) with purpura fulminans due to Enterococcus cecorum in a 51-year-old man. As opposed to other enterococci, Enterococcus cecorum remains susceptible to third-generation cephalosporin which is the first line empirical antibiotic therapy for both patients with purpura fulminans and asplenic patients with sepsis. Despite adequate antibiotic therapy, evolution in the intensive care unit (ICU) was overwhelming with death occurring 10 h after ICU admission.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial-resistant Enterococcus cecorum in poultry

Enterococcus cecorum (E. cecorum) was identified among the most relevant antimicrobial-resistant (AMR) bacteria in the EU for poultry in a previous scientific opinion. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9, and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR E. cecorum can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (33-75% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1, 2 and 4 (Categories A, B and D; 0-5%, 5-10% and 10-33% probability of meeting the criteria, respectively) and the AHAW Panel is uncertain whether it meets the criteria in Sections 3 and 5 (Categories C and E, 33-66% and 33-75% probability of meeting the criteria, respectively). The animal species to be listed for AMR E. cecorum according to Article 8 criteria are mostly birds belonging to the families of Anatidae, Columbidae and Phasianidae.

Comparison of pathogenic and non-pathogenic Enterococcus cecorum strains from different animal species

Background

Enterococcus cecorum (EC) infection currently is one of the most important bacterial diseases of modern broiler chickens but can also affect ducks or other avian species. However, little is known concerning pathogenesis of EC and most studies concentrate on examinations of EC strains from broilers only. The objective of this study was to compare pathogenic and commensal EC strains from different animal species concerning different phenotypic and genotypic traits.

Results

Pathogenic and commensal EC strains were not clearly separated from each other in a phylogenetic tree based on partial sequences of the 16S-rRNA-gene and also based on the fatty acid profile determined with gas chromatography. C_12:0, C_14:0, C_15:0, C_16:0, C_17:0, C_18:0, C_18:1 w7c, C_18:1 w9c and C_20:4 w6,9,12,15c were detected as the major fatty acids. None of the 21 pathogenic EC strains was able to utilize mannitol, while 9 of 29 commensal strains were mannitol positive. In a dendrogram based on MALDI-TOF MS data, pathogenic strains were not clearly separated from commensal isolates. However, significant differences concerning the prevalence of several mass peaks were confirmed between the two groups. Two different antisera were produced but none of the serotypes was predominantly found in the pathogenic or commensal EC isolates. Enterococcal virulence factors gelE, esp, asa1, ccf, hyl and efaAfs were only detected in single isolates via PCR. No virulence factor was found significantly more often in the pathogenic isolates. The chicken embryo lethality of the examined EC isolates varied from 0 up to 100%. The mean embryo lethality in the pathogenic EC isolates was 39.7%, which was significantly higher than the lethality of the commensal strains, which was 18.9%. Additionally, five of the commensal isolates showed small colony variant growth, which was never reported for EC before.

Conclusions

Pathogenic and commensal EC isolates from different animal species varied in chicken embryo lethality, in their ability to metabolize mannitol and probably showed divergent mass peak patterns with MALDI-TOF MS. These differences may be explained by a separate evolution of pathogenic EC isolates. Furthermore, different serotypes of EC were demonstrated for the first time.

Enterococcus cecorum sepsis in a patient with liver cirrhosis, successfully treated with ceftriaxone

Enterococcus cecorum septicemia is rare in humans. This case describes a man with underlying liver cirrhosis, a comorbidity that contributes to half of the E. cecorum infections described in the current literature. The patient was successfully treated with ceftriaxone. Identification of this species was accurately made with Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry and confirmed by 16S rDNA sequencing.

Enterococcal endocarditis revisited

The Enterococcus species is the third main cause of infective endocarditis (IE) worldwide, and it is gaining relevance, especially among healthcare-associated cases. Patients with enterococcal IE are older and have more comorbidities than other types of IE. Classical treatment options are limited due to the emergence of high-level aminoglycosides resistance (HLAR), vancomycin resistance and multidrug resistance in some cases. Besides, few new antimicrobial alternatives have shown real efficacy, despite some of them being recommended by major guidelines (including linezolid and daptomycin). Ampicillin plus ceftriaxone 2 g iv./12 h is a good option for Enterococcus faecalis IE caused by HLAR strains, but randomized clinical trials are essential to demonstrate its efficacy for non-HLAR EFIE and to compare it with ampicillin plus short-course gentamicin. The main mechanisms of resistance and treatment options are also reviewed for other enterococcal species.

Nosocomial infection due to Enterococcus cecorum identified by MALDI-TOF MS and Vitek 2 from a blood culture of a septic patient

We report the case of a nosocomial infection due to Enterococcus cecorum isolated from a blood culture of a 75-year-old septic male patient. Matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI-TOF MS) and Vitek 2 succeeded in identification of the isolate.

Enterococcus cecorum human infection, France

Enterococcus cecorum is a bacterium of the intestinal tract of many domestic animals that is rarely reported as human pathogen. Here we report the first case of incisional hernia plate infection and the first case of urinary tract colonization due to E. cecorum from patients in Marseille, France.

Comparative genomic analysis identifies divergent genomic features of pathogenic Enterococcus cecorum including a type IC CRISPR-Cas system, a capsule locus, an epa-like locus, and putative host tissue binding proteins

Enterococcus cecorum (EC) is the dominant enteric commensal of adult chickens and contributes to the gut consortia of many avian and mammalian species. While EC infection is an uncommon zoonosis, like other enterococcal species it can cause life-threating nosocomial infection in people. In contrast to other enterococci which are considered opportunistic pathogens, emerging pathogenic strains of EC cause outbreaks of musculoskeletal disease in broiler chickens. Typical morbidity and mortality is comparable to other important infectious diseases of poultry. In molecular epidemiologic studies, pathogenic EC strains were found to be genetically clonal. These findings suggested acquisition of specific virulence determinants by pathogenic EC. To identify divergent genomic features and acquired virulence determinants in pathogenic EC; comparative genomic analysis was performed on genomes of 3 pathogenic and 3 commensal strains of EC. Pathogenic isolates had smaller genomes with a higher GC content, and they demonstrated large regions of synteny compared to commensal isolates. A molecular phylogenetic analysis demonstrated sequence divergence in pathogenic EC genomes. At a threshold of 98% identity, 414 predicted proteins were identified that were highly conserved in pathogenic EC but not in commensal EC. Among these, divergent CRISPR-cas defense loci were observed. In commensal EC, the type IIA arrangement typical for enterococci was present; however, pathogenic EC had a type IC locus, which is novel in enterococci but commonly observed in streptococci. Potential mediators of virulence identified in this analysis included a polysaccharide capsular locus similar to that recently described for E. faecium, an epa-like locus, and cell wall associated proteins which may bind host extracellular matrix. This analysis identified specific genomic regions, coding sequences, and predicted proteins which may be related to the divergent evolution and increased virulence of emerging pathogenic strains of EC.

Amplicon pyrosequencing and ion torrent sequencing of wild duck eubacterial microbiome from fecal samples reveals numerous species linked to human and animal diseases

Our investigation into the composition of the wild duck,Aythya americana, eubacterial microbiome from a fecal sample using amplicon pyrosequencing revealed that the representative bacterial species were quite distinct from a pond water sample, and we were able to classify the major operational taxonomic units withFusobacterium mortiferum,Streptobacillus moniliformis,Lactobacillus intermedius,Actinomyces suimastitidis,Campylobacter Canadensis,Enterococcus cecorum,Lactobacillus aviarus,Actimomyces spp.,Pseudobutyrivibrio spp.and Helicobacter brantaerepresenting the majority of the eubacterial fecal microbiome.  Bacterial species present in the analysis revealed numerous organisms linked to human and animal diseases including septicemia, rat bite fever, pig mastitis, endocarditis, malar masses, genital infections, skin lesions, peritonitis, wound infections, septic arthritis, urocystitis, gastroenteritis and drinking water diseases.  In addition, to being known carriers of viral pathogens wild ducks should also be recognized as a potential source of a range of bacterial diseases.

Experimental reproduction of an Enterococcus cecorum infection in Pekin ducks

Enterococcus cecorum (EC) was thus far only known as a pathogen for broilers and broiler breeders. Recently there was evidence of EC field outbreaks in Pekin duck flocks in Germany. In this study we experimentally reproduced an EC infection in Pekin ducks. At 12 days post hatch, groups of Pekin ducks were infected orally, via the thoracic air sac or intravenously with 1.5 × 10(9) colony-forming units (CFU) of EC per bird or via the air sac with 8.5 × 10(5) or 8.5 × 10(7) CFU per bird. Ducks of the intravenously infected group showed 100% mortality after 2 days post infection. The air sac inoculated high-dose group exhibited a mortality rate of 67%. Birds that were infected with 8.5 × 10(5) and 8.5 × 10(7) CFU showed 6.7% mortality after 7 days post infection. Dead birds displayed pneumonia, airsacculitis, pericarditis and splenitis and EC was re-isolated from these organs. Surviving birds of all groups apart from the orally infected ducks demonstrated clinical signs such as huddling, reduced mobility and diarrhoea. Furthermore, they showed gross pathological lesions including airsacculitis and splenitis and lower bodyweights than the control group at necropsy on days 7, 14 and 21 post infection. The present study clearly confirms that EC is pathogenic for Pekin ducks after experimental infection via the intravenous route or the respiratory tract. EC therefore has to be considered as an emerging avian pathogen not only in broilers but also in Pekin ducks.

Glucose triggers ATP secretion from bacteria in a growth-phase-dependent manner

ATP modulates immune cell functions, and ATP derived from gut commensal bacteria promotes the differentiation of T helper 17 (Th17) cells in the intestinal lamina propria. We recently reported that Enterococcus gallinarum, isolated from mice and humans, secretes ATP. We have since found and characterized several ATP-secreting bacteria. Of the tested enterococci, Enterococcus mundtii secreted the greatest amount of ATP (>2 μM/10(8) cells) after overnight culture. Glucose, not amino acids and vitamins, was essential for ATP secretion from E. mundtii. Analyses of energy-deprived cells demonstrated that glycolysis is the most important pathway for bacterial ATP secretion. Furthermore, exponential-phase E. mundtii and Enterococcus faecalis cells secrete ATP more efficiently than stationary-phase cells. Other bacteria, including Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, also secrete ATP in exponential but not stationary phase. These results suggest that various gut bacteria, including commensals and pathogens, might secrete ATP at any growth phase and modulate immune cell function.

Fingerprinting of poultry isolates of Enterococcus cecorum using three molecular typing methods

Enterococcus cecorum is an emerging challenge to the broiler industry. The organism has been implicated in septicemia, spondylitis, arthritis, and osteomyelitis in commercial broilers and broiler breeders, which lead to economic losses attributed to increased mortality and culling rates, decreased average processing weights, and increased feed conversion ratios. The current study evaluated the genetic variability of 30 clinical isolates of E. cecorum from outbreaks in Pennsylvania, using 3 molecular typing methods, namely, pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA analysis, and enterobacterial repetitive intergenic consensus–PCR (polymerase chain reaction), in order to understand their genetic relatedness and to identify possible pathogenic clones. The study revealed the existence of genotypic polymorphism among E. cecorum associated with clinical disease. Of the 3 typing methods used, PFGE analysis demonstrated higher genetic variability of E. cecorum isolates compared to PCR-based methods. Also, each molecular typing method was evaluated in terms of typeability, discriminatory power, and reproducibility for application of these typing methods in fingerprinting of E. cecorum in future reference. Pulsed-field gel electrophoresis provided the most reliable results with greater discriminatory power and higher reproducibility compared to the 2 PCR-based methods.