Bacteraemic spondylodiscitis caused by Enterococcus hirae

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.

Genomic Characterization of Enterococcus hirae From Beef Cattle Feedlots and Associated Environmental Continuum

Enterococci are commensal bacteria of the gastrointestinal tract of humans, animals, and insects. They are also found in soil, water, and plant ecosystems. The presence of enterococci in human, animal, and environmental settings makes these bacteria ideal candidates to study antimicrobial resistance in the One-Health continuum. This study focused on Enterococcus hirae isolates (n = 4,601) predominantly isolated from beef production systems including bovine feces (n = 4,117, 89.5%), catch-basin water (n = 306, 66.5%), stockpiled bovine manure (n = 24, 0.5%), and natural water sources near feedlots (n = 145, 32%), and a few isolates from urban wastewater (n = 9, 0.2%) denoted as human-associated environmental samples. Antimicrobial susceptibility profiling of a subset (n = 1,319) of E. hirae isolates originating from beef production systems (n = 1,308) showed high resistance to tetracycline (65%) and erythromycin (57%) with 50.4% isolates harboring multi-drug resistance, whereas urban wastewater isolates (n = 9) were resistant to nitrofurantoin (44.5%) and tigecycline (44.5%) followed by linezolid (33.3%). Genes for tetracycline (tetL, M, S/M, and O/32/O) and macrolide resistance erm(B) were frequently found in beef production isolates. Antimicrobial resistance profiles of E. hirae isolates recovered from different environmental settings appeared to reflect the kind of antimicrobial usage in beef and human sectors. Comparative genomic analysis of E. hirae isolates showed an open pan-genome that consisted of 1,427 core genes, 358 soft core genes, 1701 shell genes, and 7,969 cloud genes. Across species comparative genomic analysis conducted on E. hirae, Enterococcus faecalis and Enterococcus faecium genomes revealed that E. hirae had unique genes associated with vitamin production, cellulose, and pectin degradation, traits which may support its adaptation to the bovine digestive tract. E. faecium and E. faecalis more frequently harbored virulence genes associated with biofilm formation, iron transport, and cell adhesion, suggesting niche specificity within these species.

Enterococcus hirae bacteremia associated with acute pyelonephritis in a patient with alcoholic cirrhosis: a case report and literature review

Background

Infections caused by Enterococcus hirae are common in animals, with instances of transmission to humans being rare. Further, few cases have been reported in humans because of the difficulty in identifying the bacteria. Herein, we report a case of pyelonephritis caused by E. hirae bacteremia and conduct a literature review on E. hirae bacteremia.

Case presentation

A 57-year-old male patient with alcoholic cirrhosis and neurogenic bladder presented with fever and chills that had persisted for 3 days. Physical examination revealed tenderness of the right costovertebral angle. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) of the patient’s blood and urine samples revealed the presence of E. hirae, and pyelonephritis was diagnosed. The patient was treated successfully with intravenous ampicillin followed by oral linezolid for a total of three weeks.

Conclusion

The literature review we conducted revealed that E. hirae bacteremia is frequently reported in urinary tract infections, biliary tract infections, and infective endocarditis and is more likely to occur in patients with diabetes, liver cirrhosis, and chronic kidney disease. However, mortality is not common because of the high antimicrobial susceptibility of E. hirae. With the advancements in MALDI-TOF MS, the number of reports of E. hirae infections has also increased, and clinicians need to consider E. hirae as a possible causative pathogen of urinary tract infections in patients with known risk factors.

First Danish case of infective endocarditis caused by Enterococcus hirae

Enterococcus hirae, a member of the Enterococcus genus, is known to cause infections, including infective endocarditis (IE), in animal species. In humans, E. hirae is an uncommon pathogen, but has been associated with severe and recurrent disease. Here, we report the first Danish case of E. hirae native aortic valve IE in a 62-year-old woman with no history of heart disease. She presented to the hospital with symptoms of gastroenteritis but no signs of heart disease. Nevertheless, blood culture revealed growth of E. hirae, and a transoesophageal echocardiography demonstrated a mobile mass adherent to the aortic valve, compatible with a vegetation. The patient was successfully treated for E. hirae native aortic valve IE with 4 weeks of intravenous benzylpenicillin in combination with gentamicin for the initial 2 weeks. To the best of our knowledge, this is the first documented case of E. hirae IE in Denmark and the sixth documented case worldwide.

Enterococcus hirae Bacteremia in an Infant: Case Report and Review of the Literature

Enterococcus hirae is a gram-positive coccus that is rarely implicated in human disease and has not been reported in pediatric patients. We report a case of catheter-associated bloodstream infection and prolonged bacteremia in a 7-month-old infant dependent on total parenteral nutrition. The species was identified by the VITEK2 system and confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The organisms was susceptible to ampicillin, vancomycin, and high-level gentamicin. The patient was treated with vancomycin and gentamicin with adjunctive vancomycin lock therapy but had persistent bacteremia. Therapy was changed to dual β-lactam therapy of ampicillin and ceftriaxone with synergistic gentamicin, which led to clearance of the enterococcal bacteremia. E hirae is an unusual species that may be difficult for the microbiology laboratory to identify. This is the first pediatric case and the second case of invasive E hirae in the United States.

Bacteremic pneumonia caused by Enterococcus hirae in a subject receiving regorafenib

INTRODUCTION

Infections due to Enterococcus hirae have rarely been reported in humans but are not uncommon in mammals and birds. We describe a case of E. hirae bacteremia and pneumonia in a bird breeder and its potential relationship with regorafenib, a tirosin kinase inhibitor (TKI).

METHODS

Descriptive study and review of the literature through a PubMed search of the cases described previously to date.

RESULTS

Only seventeen cases have been described, mainly endocarditis, pyelonephritis, and intraabdominal infections. No cases of pneumonia have been reported so far. The recent increase in TKI use opens a new field to explore in infectious diseases due to both the exposure to these immunosuppressive drugs and the increased survival of subjects with severe underlying comorbidities.

CONCLUSION

In patients in contact with birds, immunosuppressed by their underlying morbidities and treated with regorafenib, clinicians should be aware of an increased risk of unusual potentially severe infections.

The application of the loop-mediated isothermal amplification (LAMP) method for diagnosing Enterococcus hirae-associated endocarditis outbreaks in chickens

BACKGROUND

Enterococcus hirae is considered a part of the normal intestinal biota of several domestic animals, including poultry. However, this species is also associated with infective endocarditis in chickens, a disease that leads to unexpected deaths and serious economical losses. Enterococcus hirae is identified predominantly with the use of conventional bacteriological methods, biochemical tests and PCR. Rapid, sensitive and specific methods for detecting E. hirae in clinical samples are required in poultry production. The aim of this study was to use the Loop-Mediated Isothermal Amplification (LAMP) for the identification and quantification of E. hirae in heart samples from broiler chickens.

RESULTS

The specificity of the LAMP method was confirmed for 7 enterococcal strains and 3 non-enterococcal strains. E. hirae was detected in all of the 22 analyzed clinical bacterial isolates and in all of the 9 heart samples. Three sets of primers supported the detection of E. hirae with high sensitivity and specificity within one hour. The highest detection rate of a LAMP product was approximately 7 min for an E. hirae strain and 12 min for a positive heart sample. The detection limit for the E. hirae ATCC 10541 standard was 1.3 × 10² CFU (43.4 fg) or 13.8 copies of the E. hirae genome equivalent per reaction. The reaction was 10-fold more sensitive than conventional species-specific PCR. The LAMP assay supported the determination of the E. hirae load in chicken hearts with endocarditis in field cases. The average number of E. hirae cells in hearts was 5.19 × 10⁷ CFU/g of tissue, and the average number of E. hirae genome equivalents in hearts was 5.51× 10⁶ copies/g of tissue. Bacterial counts were significantly higher in the LAMP assay than in the standard plate count.

CONCLUSIONS

The LAMP assay is a useful diagnostic tool and an effective alternative to conventional methods for the detection of this enterococcal species. The sodA-based LAMP assay supported direct identification of E. hirae from pure cultures and heart samples without previous bacterial cultivation. This is the first study to apply the LAMP method for the purpose of diagnosing E. hirae-associated endocarditis in poultry.

Antimicrobial Resistance in Enterococcus spp. of animal origin

Enterococci are natural inhabitants of the intestinal tract in humans and many animals, including food-producing and companion animals. They can easily contaminate the food and the environment, entering the food chain. Moreover, Enterococcus is an important opportunistic pathogen, especially the species E. faecalis and E. faecium, causing a wide variety of infections. This microorganism not only contains intrinsic resistance mechanisms to several antimicrobial agents, but also has the capacity to acquire new mechanisms of antimicrobial resistance. In this review we analyze the diversity of enterococcal species and their distribution in the intestinal tract of animals. Moreover, resistance mechanisms for different classes of antimicrobials of clinical relevance are reviewed, as well as the epidemiology of multidrug-resistant enterococci of animal origin, with special attention given to beta-lactams, glycopeptides, and linezolid. The emergence of new antimicrobial resistance genes in enterococci of animal origin, such as optrA and cfr, is highlighted. The molecular epidemiology and the population structure of E. faecalis and E. faecium isolates in farm and companion animals is presented. Moreover, the types of plasmids that carry the antimicrobial resistance genes in enterococci of animal origin are reviewed.

Acute Pyelonephritis with Bacteremia Caused by Enterococcus hirae: A Rare Infection in Humans

Enterococci are one of the usual residents of the microflora in humans. In the last decade this genus has been reported as the third most common cause of bacteremia. We present the case of a 78-year-old female who was admitted to the emergency room because of nausea, lipothymia, and weakness. She was diagnosed with a pyelonephritis with bacteremia, with the isolation in blood and urine cultures of Escherichia coli and Enterococcus hirae. This last microorganism is a rarely isolated pathogen in humans. Currently it is estimated to represent 1–3% of all enterococcal species isolated in clinical practice.

Enterococcus hirae Bacteremia Associated with Acute Pancreatitis and Septic Shock

Infection with Enterococcus hirae has rarely been reported in humans but is not uncommon in mammals and birds. We describe a case of Enterococcus hirae bacteremia associated with acute pancreatitis, acute cholecystitis, and septic shock responsive to antibiotic therapy and supportive critical care management. Unique aspects of this case of Enterococcus hirae bacteremia are its association with acute pancreatitis and its geographical origin. To our knowledge, this is the first report of Enterococcus hirae bacteremia occurring in a patient in the United States. Although human infection with this organism appears to be rare, all cases reported to date describe bacteremia associated with severe and life-threatening illness. Thus, physicians need to be cognizant of the clinical significance of this heretofore little recognized pathogen.

Enterococcus hirae, an unusual pathogen in humans causing urinary tract infection in a patient with benign prostatic hyperplasia: first case report in Algeria

Enterococcus hirae is a zoonotic pathogen rarely isolated from human infections. This case is the first description of E. hirae causing urinary tract infection in a diabetic man with benign prostatic hyperplasia from Algeria. The clinical isolate was identified by MALDI-TOF MS and displayed a multisensitivity antibiotic profile.

Native Valve Endocarditis due to Enterococcus hirae Presenting as a Neurological Deficit

Enterococcus hirae is a rare isolate in clinical specimens. We describe a case of native aortic valve endocarditis in a 56-year-old man. This is the third reported case of endocarditis due to this organism, the first without recurrence of endocarditis and the first presenting as a neurological deficit.

Spontaneous bacterial peritonitis with sepsis caused by Enterococcus hirae

Selective intestinal decontamination (SID) with norfloxacin has been widely used for the prophylaxis of spontaneous bacterial peritonitis (SBP) because of a high recurrence rate and preventive effect of SID for SBP. However, it does select resistant gut flora and may lead to SBP caused by unusual pathogens such as quinolone-resistant gram-negative bacilli or gram-positive cocci. Enterococcus hirae is known to cause infections mainly in animals, but is rarely encountered in humans. We report the first case of SBP by E. hirae in a cirrhotic patient who have previously received an oral administration of norfloxacin against SBP caused by Klebsiella pneumoniae and presented in septic shock.

Enterococcus hirae-related acute pyelonephritis and cholangitis with bacteremia: an unusual infection in humans

Very few reports are available from the literature related to Enterococcus hirae infection in humans, which is more frequently seen in animals and birds. We report two patients with E hirae bacteremia caused by acute pyelonephritis and acute cholangitis. The clinical courses have been smooth on use of sensitive antibiotic therapy. In both cases, the primary sources and portals of entry are clearly identified.

Relapse of Enterococcus hirae prosthetic valve endocarditis

Enterococcus hirae, a gram-positive bacterium, is a rare isolate in clinical specimens. We report an unusual case of a relapse of prosthetic valve endocarditis due to E. hirae 6 months after the initial episode. Clonal relationship was proven by genomic analysis.

Bacteremia caused by non-faecalis and non-faecium enterococcus species at a Medical center in Taiwan, 2000 to 2008

SUMMARY OBJECTIVES

Human infections due to non-faecalis and non-faecium Enterococcus species are emerging but data on the characteristics of these infections are limited.

METHODS

We retrospectively reviewed the computerized database of the bacteriology laboratory at National Taiwan University Hospital from January 2000 through December 2008 to identify patients with non-faecalis and non-faecium enterococcal bacteremia.

RESULTS

Enterococcal bacteremia was diagnosed in 1887 patients during the study period and was caused by non-faecalis and non-faecium enterococci in 182 (9.6%) of these patients. The causative organisms included Enterococcus casseliflavus (n = 59, 3.1%), Enterococcus gallinarum (n = 58, 3.0%), Enterococcus avium (n = 45, 2.4%), Enterococcus hirae (n = 9, 0.5%), Enterococcus raffinosus (n = 9, 0.5%), Enterococcus durans (n = 2, 0.1%), Enterococcus cecorum (n = 2, 0.1%), and Enterococcus canintestini (n = 1, 0.5%). A commercially-available phenotypic identification system misidentified six isolates based upon sequence analysis of 16S and groESL genes. Among the 182 patients, 74 (40.7%) had catheter-associated bloodstream infection and 69 (37.9%) presented with biliary tract infection. Healthcare-associated enterococcal bacteremia comprised 99 (54.4%) episodes and a polymicrobial etiology was found in 106 (58.2%) episodes. The clinical manifestations varied between the infecting Enterococcus species. Multivariate logistic regression showed that immunocompromised status is the only risk factor for the all cause mortality.

CONCLUSIONS

Non-faecalis and non-faecium Enterococcus species can cause protean manifestations which vary with the infecting Enterococcus species. Misidentification of unusual enterococcal species might occur by the commercial identification methods and accurate identification with molecular methods is required.