Helcococcus Kunzii Research Articles

Interactions between Helcococcus kunzii and Staphylococcus aureus: How a commensal bacterium modulates the virulence and metabolism of a pathogen in a chronic wound in vitro model

BackgroundStaphylococcus aureus is the predominant pathogen isolated in diabetic foot infections. Recently, the skin commensal bacterium, Helcococcus kunzii, was found to modulate the virulence of this pathogen in an in vivo model. This study aims to elucidate the molecular mechanisms underlying the interaction between these two bacterial species, using a proteomic approach.ResultsOur results reveal that H. kunzii can coexist and proliferate alongside S. aureus in a Chronic Wound Media (CWM), thereby mimicking an in vitro chronic wound environment. We noted that the secreted proteome of H. kunzii induced a transcriptional effect on S. aureus virulence, resulting in a decrease in the expression level of agrA, a gene involved in quorum sensing. The observed effect could be ascribed to specific proteins secreted by H. kunzii including polysaccharide deacetylase, peptidoglycan DD-metalloendopeptidase, glyceraldehyde-3-phosphate dehydrogenase, trypsin-like peptidase, and an extracellular solute-binding protein. These proteins potentially interact with the agr system, influencing S. aureus virulence. Additionally, the virulence of S. aureus was notably affected by modifications in iron-related pathways and components of cell wall architecture in the presence of H. kunzii. Furthermore, the overall metabolism of S. aureus was reduced when cocultured with H. kunzii.ConclusionFuture research will focus on elucidating the role of these excreted factors in modulating virulence.

Proteomic insights into Helcococcus kunzii in a diabetic foot ulcer-like environment.

Helcococcus kunzii is a skin commensal, Gram-positive bacterium, mostly isolated from infected chronic wounds. This opportunistic pathogen is usually co-isolated with Staphylococcus aureus. The present dataset explores the production and secretion of H. kunzii bacterial virulence interacting proteins in a growth medium mimicking chronic wounds in exponential and stationary growth phases. The H. kunzii cellular proteome and exoproteome were assessed by analyzing three biological replicates per condition tested. Samples were analyzed using a Q-Exactive HF mass spectrometer. Comparative and functional analyses were performed to profile the identified protein set. The H. kunzii's cellular proteome encompassed 969 proteins, among which 64 and 53 were specifically identified in the exponential and stationary phase of growth, respectively. Its exoproteome comprised 58 proteins, among which 16 and 14 were characteristic of each growth stage. Metabolic differences between the two phases of growth are discussed. Besides, the production of previously shortlisted and novel putative H. kunzii targets involved in modulating the virulence of S. aureus is investigated. This work, pioneering the study of H. kunzii physiology in a chronic wound-like environment, should assist future research on this opportunistic pathogen and the search for innovative approaches for wound management.

A case of Helcococcus kunzii infection

Helcococcus is a resident bacteria in human and animal skin. It is a rare opportunistic pathogen in humans. Helcococcus kunzii, which causes mainly skin infection, was first discovered by Collins in 1993 [1]. At present, there are few case reports of infection caused by Helcococcus kunzii. Here, we report a case of Helcococcus kunzii infection admitted to our department, to increase the understanding of its diagnosis and treatment in the clinic.

Comparative genomics analysis of two Helcococcus kunzii strains co-isolated with Staphylococcus aureus from diabetic foot ulcers

Helcococcus kunzii is a commensal Gram-positive bacterial species recovered from the human skin microbiota and considered as an opportunistic pathogen. Although little is known about its clinical significance, its increased abundance has been reported in infected wounds, particularly in foot ulcers in persons with diabetes. This species is usually detected in mixed cultures from human specimens and frequently isolated with Staphylococcus aureus. Modulation of staphylococci virulence by H. kunzii has been shown in an infection model of Caenorhabditis elegans. The aim of this study was to compare the genomes of two H. kunzii strains isolated from foot ulcers -isolate H13 and H10 showing high or low impact on S. aureus virulence, respectively- and the H. kunzii ATCC51366 strain. Whole genome analyses revealed some differences between the two strains: length (2.06 Mb (H13) and 2.05 Mb (H10) bp), GC content (29.3% (H13) and 29.5% (H10)) and gene content (1,884 (H13) and 1,786 (H10) predicted genes). The core-proteome phylogenies within the genus characterised H. kunzii H13 and H10 as genetically similar to their ancestor. The main differences between the strains were mainly in sugar-associated transporters and various hypothetical proteins. Five targets were identified as potentially involved in S. aureus virulence modulation in both genomes: the two-component iron export system and three autoinducer-like proteins. Moreover, H13 strain harbours a prophage inserted in 1,261,110-1,295,549 (attL-attR), which is absent in H10 strain. The prophage PhiCD38_2 was previously reported for its ability to modulate secretion profile, reinforcing the autoinducer-like hypothesis. In the future, transcriptomics or metaproteomics approaches could be performed to better characterize the H13 strain and possibly identify the underlying mechanism for S. aureus virulence modulation.

16S rDNA PCR for the aetiological diagnosis of culture-negative infective endocarditis

Culture-negative infective endocarditis (IE) accounts for 7-31% of all cases. Metagenomics has contributed to improving the aetiological diagnosis of IE patients undergoing valve surgery. We assessed the impact of 16S ribosomal DNA gene polymerase chain reaction (16S rDNA PCR) in the aetiological diagnosis of culture-negative IE. Between January 2016 and January 2020, clinical data from culture-negative IE patients were reviewed retrospectively. Identification of bacteria was performed using 16S rDNA PCR in heart valve specimens. 36 out of 313 patients (12%) with culture-negative IE had their valve tissue specimens submitted for 16S rDNA PCR. 16S rDNA PCR detected and identified bacterial nucleic acid in heart valve tissue significantly more frequently compared to valve culture alone 25(70%) vs 5(12%); p < 0.05. Mean age was 57years (SD 18) and 80% were male. Native and aortic valve were involved in 76% and 52% of cases, respectively. Streptococcus spp. (n 15) were the most commonly detected organisms, followed by bacteria of the HACEK group (Haemophilus parainfluenzae 2, Aggregatibacter actinomycetemcomitans 1), nutritionally variant streptococci (Abiotrophia defectiva 2), and one each of Staphylococcus aureus, Corynebacterium pseudodiphtheriticum, Helcococcus kunzii, Neisseria gonorrhoeae, Tropheryma whipplei. 16S rDNA PCR may be a useful diagnostic tool for the identification of the causative organism in culture-negative IE. Efforts towards a shorter turnaround time for results should be consider and further studies assessing the clinical impact of this technique in culture-negative IE are needed.

First Chinese case report of Helcococcus kunzii in a patient with diabetic foot

BackgroundInfection of Helcococcus kunzii(H. kunzii) from diabetic foot wound is rarely reported. This case report describes the infection of H.kunzii and highlights the therapeutic effect on H.kunzii from a diabetic foot wound.Case presentationIn this study, one H. kunzii strain was isolated from a patient with diabetic foot, which was confirmed by 16S rRNA gene analysis and MALDI-TOF-MS. It is the first Chinese case of H. kunzii in a patient with diabetic foot. As a result of the lack of antibiotic sensitivity data and multiple comorbidities, antibiotics were used cautiously, and those administered during the first 3 months were ineffective. Then, vacuum sealing drainage (VSD) was applied during hospitalization; no antibiotics were used and the wound healed well.ConclusionsVSD alone may be more effective in treating diabetic feet infected with H. kunzii, which may provide reference for clinical treatment of H. kunzii infection from diabetic foot.

Helcococcus kunzii methyltransferase Erm(47) responsible for MLSB resistance is induced by diverse ribosome-targeting antibiotics.

To determine the mechanism of induction of erm(47) and its atypical expression in the Gram-positive opportunistic pathogen Helcococcus kunzii, where it confers resistance to a subset of clinically important macrolide, lincosamide and streptogramin B (MLSB) antibiotics. The resistant H. kunzii clinical isolate UCN99 was challenged with subinhibitory concentrations of a wide range of ribosome-targeting drugs. The methylation status of the H. kunzii ribosomal RNA at the MLSB binding site was then determined using an MS approach and was correlated with any increase in resistance to the drugs. The H. kunzii erm(47) gene encodes a monomethyltransferase. Expression is induced by subinhibitory concentrations of the macrolide erythromycin, as is common for many erm genes, and surprisingly also by 16-membered macrolide, lincosamide, streptogramin, ketolide, chloramphenicol and linezolid antibiotics, all of which target the 50S ribosomal subunit. No induction was detected with spectinomycin, which targets the 30S subunit. The structure of the erm(47) leader sequence functions as a hair trigger for the induction mechanism that expresses resistance. Consequently, translation of the erm(47) mRNA is tripped by MLSB compounds and also by drugs that target the 50S ribosomal subunit outside the MLSB site. Expression of erm(47) thus extends previous assumptions about how erm genes can be induced.

A case of lower limbs infection caused by Helcococcus Kunzii and literature analysis

Objective To describe a case of lower limbs infection of Helcococcus Kunzii in North China University of Science and Technology Affiliated Hospital in October 2017 and to analyze the etiology and drug susceptibility. Methods The bacteria were identified by French Meriere mass spectrometer and BD Phoenix-100 automatic bacterial identification/drug sensitivity system.The drug resistance of the bacteria was detected by disk diffusion method, and collected the clinical information and related literature information of the Helcococcus Kunzi to analyze. Results The Gram-positive cocci was isolated from the foot secretion of a patient with venous thrombosis of lower limbs complicated with infection.The result of smear was Gram-positive cocci in double, agglomerate and varied in size.On the blood plate, there was a small colony of α hemolysis.Thixozyme negative, β galactosidase negative.The results of mass spectrometry identification and two kinds of fully automatic bacterial identification / drug sensitivity system were identified as Helcococcus Kunzii, the isolates was resistant to erythromycin and clindamycin among the 10 antibiotics tested.By searching, sorting out and analyzing the literature information, it is revealed that the infection of this bacterium is not related to sex.Middle-aged and elderly people are mostly infected.And the cocci easily infected patients with lower immunity.The infection of lower limbs is 47.37%, the infection of blood flow is 15.79% and the other ways of infection are 42.11% (lung, mammary gland, etc.). Conclusion Helcococcus Kunzii is a conditional pathogen, and patients with lower immunity are more common.Erythromycin resistance could identify it from the green balloon bacteria.Moreover, the bacteria could cause a wide spectrum of diseases, and easily cause sepsis and lower limbs infections, which reminds us that we should be vigilant in clinical practice. Key words: Helcococcus Kunzii; Lower limb infection; Mass spectrometry identification; Drug resistance detection

Helcococcus kunzii prosthetic valve endocarditis secondary to lower extremity cellulitis

An 88-year-old man with history of bioprosthetic aortic valve replacement was hospitalised with fever, chills, malaise and right lower extremity cellulitis. Laboratory investigations revealed leucocytosis and blood cultures grew Helcococcus...

Decrease of Staphylococcus aureus Virulence by Helcococcus kunzii in a Caenorhabditis elegans Model

Social bacterial interactions are considered essential in numerous infectious diseases, particularly in wounds. Foot ulcers are a common complication in diabetic patients and these ulcers become frequently infected. This infection is usually polymicrobial promoting cell-to-cell communications. Staphylococcus aureus is the most prevalent pathogen isolated. Its association with Helcococcus kunzii, commensal Gram-positive cocci, is frequently described. The aim of this study was to assess the impact of co-infection on virulence of both H. kunzii and S. aureus strains in a Caenorhabditis elegans model. To study the host response, qRT-PCRs targeting host defense genes were performed. We observed that H. kunzii strains harbored a very low (LT50: 5.7 days ± 0.4) or an absence of virulence (LT50: 6.9 days ± 0.5). In contrast, S. aureus strains (LT50: 2.9 days ± 0.4) were significantly more virulent than all H. kunzii (P < 0.001). When H. kunzii and S. aureus strains were associated, H. kunzii significantly reduced the virulence of the S. aureus strain in nematodes (LT50 between 4.4 and 5.2 days; P < 0.001). To evaluate the impact of these strains on host response, transcriptomic analysis showed that the ingestion of S. aureus led to a strong induction of defense genes (lys-5, sodh-1, and cyp-37B1) while H. kunzii did not. No statistical difference of host response genes expression was observed when C. elegans were infected with either S. aureus alone or with S. aureus + H. kunzii. Moreover, two well-characterized virulence factors (hla and agr) present in S. aureus were down-regulated when S. aureus were co-infected with H. kunzii. This study showed that H. kunzii decreased the virulence of S. aureus without modifying directly the host defense response. Factor(s) produced by this bacterium modulating the staphylococci virulence must be investigated.

由孔氏创伤球菌引起糖尿病性足病感染的个案报道

背景：孔氏创伤球菌是兼性厌氧菌，最初被认为是一种人体下肢皮肤的正常菌群，因孔氏创伤球菌引起侵袭性感染的病例在国内外文献报道中极其罕见，现报道我院中医外科一例由此菌引起的糖尿病足的病历。病例：患者为67岁女性以糖尿病足收入我院中医外科，术中和术后取分泌物做细菌培养，两次结果均培养出孔氏创伤球菌，后经左氧氟沙星静脉滴注和我院自制中药联合用药后，病情明显好转后出院。讨论：本文报道的病例在国内是第一例由孔氏创伤球菌引起的糖尿病性足病感染的病例，现在随着大量抗生素的使用，原认为是人体正常菌群的孔氏创伤球菌，也会引起人体侵袭性感染，应引起广大临床工作者的高度重视。 Background: Helcococcus kunzii is a facultative anaerobic bacteria, which was originally consi-dered a normal flora of human lower limb skin. The cases of invasive infection caused by Helco-coccus kunzii are extremely rare in domestic and foreign literature. In this paper, the patient with diabetes mellitus caused by Helcococcus kunzii is reported. The patient was 67 year old female with diabetes foot in our hospital surgery. In and after operation, the secretions were taken for bacterial culture. Helcococcus kunzii has been cultured two times. After the intravenous drip of levofloxacin and the combination of Chinese herbal medicine in our hospital, the condition of the patient improved significantly and discharged. Discussion: What has reported in this article is the first case of invasive trauma caused by the pathogen of diabetic foot disease cases in the country. Now with the use of a large number of antibiotics, Helcococcus kunzii, which was originally considered the normal bacteria of body can also cause the body invasive infection. And clinical workers should attach great importance to Helcococcus kunzii.

A Rare Case of Fournier’s Gangrene caused by &lt;em&gt;Helcococcus kunzii&lt;/em&gt;

Fournier’s gangrene is an acute rapidly progressing form of necrotizing fasciitis involving the genitalia and perianal regions. Trauma and local infection are the most common risk factors especially in the setting of diabetes. It is usually a polymicrobial infection caused by skin flora of the genital area. The most commonly isolated aerobic microorganism are Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus, while Bacteroides fragilis is a common culprit from the anaerobic group. We report a patient with Fournier’s gangrene caused by Helcococcus kunzii; anaerobic gram-positive coccus not known to be associated with Fournier’s gangrene before.

Novel chromosome-encoded erm(47) determinant responsible for constitutive MLSB resistance in Helcococcus kunzii.

The aim of the study was to identify the determinant responsible for erythromycin resistance in Helcococcus kunzii clinical isolate UCN99 and to characterize the genetic support and environment of this novel gene. MICs were determined using the broth microdilution method according to EUCAST guidelines. The entire genome sequence of H. kunzii UCN99 was determined using a 454/Roche GS Junior sequencer. The fragment encompassing the new resistance gene and its own promoter was cloned into the pAT29 shuttle vector and the recombinant plasmid pAT29Ωerm(47) was expressed in both Staphylococcus aureus and Streptococcus agalactiae. The transcription start site (TSS) was experimentally determined by 5' RACE-PCR. UCN99 exhibited a constitutive macrolide/lincosamide/streptogramin B (MLSB) resistance phenotype, suggesting the presence of an Erm protein. WGS allowed the identification of a novel gene, named erm(47), encoding a protein sharing 44%-48% amino acid identity with known Erm methylases. In both S. aureus and S. agalactiae, the introduction of pAT29Ωerm(47) conferred a significant increase (≥16-fold) in MICs of all macrolides and lincosamides tested, as well as a 4-fold increase in MICs of quinupristin (streptogramin B), confirming the MLSB resistance. The TSS identification revealed the presence of a short leader peptide, potentially implicated in a translational attenuation mechanism. It was also demonstrated that erm(47) was harboured by a 81 kb genomic island integrated into a chromosomal gene. This is the first description of a novel MLSB resistance determinant, named erm(47). The prevalence of this gene among Gram-positive cocci must be further investigated to determine its clinical significance.

In vitro antimicrobial susceptibility of Helcococcus kunzii and molecular analysis of macrolide and tetracycline resistance.

Thanks to the recent advent of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) technology, Helcococcus kunzii is now easily identifiable and considered as an opportunistic pathogen. However, data about antimicrobial susceptibilities remain very limited. The aim of the study was, then, to assess its in vitro susceptibility to 18 antimicrobial agents and to investigate the genetic basis of macrolide and tetracycline resistance. Thirty-nine human clinical isolates of H. kunzii collected from 2008 to 2013 were studied, as well as the type strain ATCC 51366(T). Minimum inhibitory concentrations (MICs) of penicillin G, amoxicillin, cefotaxime, imipenem, gentamicin, erythromycin, clindamycin, quinupristin-dalfopristin, ciprofloxacin, levofloxacin, tetracycline, tigecycline, vancomycin, teicoplanin, linezolid, daptomycin, cotrimoxazole and rifampin were determined by the microdilution method. Screening for macrolide [erm(A) including erm(TR), erm(B), erm(C), erm(F), erm(T), erm(X), msr(A) and mef(A)] and tetracycline [tet(L), tet(M) and tet(O)] resistance genes was performed, as well as the detection of mutations in 23S rRNA. Except for one strain resistant to cefotaxime, all strains were categorised as susceptible to β-lactams, glycopeptides, linezolid, daptomycin and tigecycline. Whereas ciprofloxacin and gentamicin exhibited limited activity, 95% of strains were categorised as susceptible to levofloxacin. Concerning erythromycin, a bimodal distribution was observed, with 29 'wild-type' strains (MICs from 0.25 to 2 mg/L) and 11 'resistant' strains (MICs ≥ 256 mg/L), including ten harbouring erm(TR). Two isolates exhibited acquired tetracycline resistance (MICs of 16 mg/L) by the production of tet(M). This large study on the in vitro antimicrobial susceptibility of H. kunzii suggests that β-lactams (especially penicillins) should be preferred for the treatment.

Identification and Clinical Significance of Helcococcus kunzii in Human Samples.

From 2008 to 2013, 39 Helcococcus kunzii strains were collected from human clinical specimens (79% from foot ulcers), and 85% of the 39 patients were infected. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and molecular methods accurately identified all isolates. This large study of clinical observations confirms the potential pathogenic role of H. kunzii.

Management of chronic osteomyelitis of the tibia with life‐threatening complications under negative pressure wound therapy and isolation of Helcococcus kunzii

We report the case of an 86-year-old man with severe wound infection originating from a chronic crural ulcer of the lower limb, which under negative pressure wound therapy led to excessive tissue necrosis and perforation of the anterior tibial artery. A swab taken 10 and 7 days preoperatively was positive for Helcococcus kunzii. H. kunzii has been described as a potentially pathogenic organism. The questions whether the negative pressure wound therapy itself caused the bleeding or the negative pressure wound therapy, which generates an anaerobic atmosphere, has triggered the growth and invasion of the facultative anaerobic bacterium H. kunzii and owing to the infection the artery perforated or whether the bacteria has no influence at all remain currently unanswered. After surgical debridement the signs of infection were completely eliminated, and a free musculocutaneous flap led to rapid healing of the wound. Following which H. kunzii was no longer detectable.

Helcococcus kunzii and Helcococcus ovis isolated in dairy cows with puerperal metritis

Puerperal metritis is a common disease in the first 3 weeks after calving in dairy cattle. Complicated par-turitions and retained placenta are factors facilitating contamination of the uterine lumen by environmental and opportunistic pathogens. Post-partum uterine in-fections are considered factors able to reduce animal welfare and fertility, causing economic losses and ear -ly animal elimination from the herd (Williams et al., 2007). The most common pathogens associated with metritis are

Prosthetic Joint Infection Caused by Helcococcus kunzii

Helcococcus kunzii was isolated by sonication and conventional cultures obtained from a case of infection following total knee prosthesis in an immunocompetent patient. The patient recovered uneventfully. This is the first known case of an H. kunzii prosthetic joint infection.

Surface bacteriology of venous leg ulcers and healing outcome

AimBacteria can be cultured from all venous leg ulcers (VLUs) regardless of healing status, and the significance of a positive swab result in non-clinically infected ulcers is unknown. The aim...

Helcococcus kunzii Isolated from a Sow with Purulent Urocystitis

Helcococcus kunzii has never been reported in veterinary medicine. The isolation of H. kunzii from a sow with purulent urocystitis is described, suggesting this organism's potential pathogenic role in swine.