Biofilm production by multiresistant Corynebacterium striatum associated with nosocomial outbreak

Bacterial pathogen assemblages on microplastic biofilms in coastal waters

Microplastic pollution in coastal ecosystems poses significant environmental risks. Microplastic biofilms were investigated through field incubation in coastal waters over a 21-day period to identify harmful microorganisms. Screening results indicated generally low abundance but highly diverse and variable nature of harmful pathogens on microplastics, largely governed by polymer type in conjunction with water usage. Typhoon shelter exhibited the highest pathogen abundance in both seawater and microplastic biofilms, with the most dominant pathogen species on microplastic biofilms being the atypical Corynebacterium variabile primarily enriched on polystyrene biofilms. Other harmful species, such as Vibrio, Acinetobacter, and Pseudomonas, were found sporadically recruited. Functional annotation and network analysis indicated a co-occurrence of pathogen taxa with keystone taxa like Aeromonas, yet no significant correlation with ARGs. This study showed that the assemblage of pathogens in the plastisphere could be influenced by multiple factors, providing a valuable reference for assessing microplastic-related pathogen risks in coastal waters.

Intervention of Corynebacterium striatum in the sessile lifestyle of Staphylococcus aureus wild-type and mutants for ica genes in polymicrobial biofilms

This study investigated the interactions between Corynebacterium striatum and Staphylococcus aureus, two bacterial species commonly found in the human microbiota, particularly colonizing the skin and mucous membranes. Both organisms, however, are also capable of causing acute and chronic infections. While S. aureus is widely recognized as a clinically significant pathogen, C. striatum is frequently underestimated and often regarded as a contaminant-even when isolated in pure culture from nosocomial infections. The ability of these microorganisms to develop multidrug resistance and form biofilms complicates the management of the infections they cause. This study focused on the interaction between C. striatum and S. aureus, particularly the influence of the former on the pathogenic potential of the latter, emphasizing biofilm formation in S. aureus mutants deficient in the icaR and icaC genes. Antimicrobial susceptibility testing revealed that 85.7 % of the S. aureus strains were multidrug-resistant, with all strains resistant to β-lactam antibiotics. Additionally, 55.6 % of the strains produced strong slime on Congo Red agar, indicating a high potential for biofilm formation. In monomicrobial assays, both C. striatum and S. aureus exhibited enhanced adhesion to hydrophilic surfaces. In polymicrobial settings, C. striatum predominated in most cases: on glass surfaces, 70 % of biofilms were dominated by C. striatum, 20 % by S. aureus, and 10 % showed an even distribution. On polystyrene, 80 % of the biofilms were dominated by C. striatum, while 20 % were dominated by S. aureus. Analysis of extracellular polymeric substances (EPS) revealed distinct compositional profiles: C. striatum primarily produced proteinaceous matrices, whereas S. aureus biofilms were rich in polysaccharides. Ultrastructural examination showed that S. aureus formed dense clusters embedded in large amounts of EPS, while C. striatum biofilms exhibited lower EPS production overall. Furthermore, the effect of C. striatum-derived compounds on S. aureus biofilms was assessed. In 90 % of co-cultured strains, a progressive decrease in sessile cell populations was observed, accompanied by an increase in planktonic cells. This finding suggests that C. striatum can disrupt the biofilm integrity of S. aureus, potentially modulating its pathogenic phenotype. In conclusion, the results demonstrate that C. striatum competes effectively with S. aureus for surface colonization and, under certain conditions, may induce a transition of S. aureus from a sessile to a planktonic state. These findings highlight the complexity of interspecies interactions in polymicrobial communities and suggest that C. striatum may play a modulatory role in S. aureus virulence. Such insights have important implications for the understanding and treatment of polymicrobial infections.

Rising prevalence and drug resistance of Corynebacterium striatum in lower respiratory tract infections

Corynebacterium striatum (C. striatum) is a Gram-positive bacterium commonly colonizing the skin and mucosa in healthy individuals and hospitalized patients. Traditionally regarded as a contaminant, C. striatum is now increasingly recognized as a potential cause of clinical infections, especially after the coronavirus disease pandemic. It has emerged as a pathogen implicated in severe infections, including pneumonia, bacteremia, meningitis, artificial joint infections, abdominal infections, and endocarditis. C. striatum has been reported in lower respiratory tract infections, mostly as a conditioned pathogen in immunocompromised individuals, particularly in those with chronic structural lung diseases, such as chronic obstructive pulmonary disease, leading to severe pneumonia or exacerbation of the existing disease and high mortality. Additionally, C striatum has been implicated in the community-acquired pneumonia among immunocompetent individuals and nosocomial lung infections, with evidence of person-to-person transmission through caregivers. C. striatum may exhibit multidrug resistance. Vancomycin, alone or in combination, is currently considered the most effective treatment for C. striatum. This review highlights the epidemiological characteristics, drug resistance mechanisms, diagnostics approaches, and treatment options for C. striatum lower respiratory tract infections to enhance clinician awareness and improve patient management strategies.

Relapsing peritoneal dialysis-associated peritonitis caused by Corynebacterium striatum: a case report

Peritoneal dialysis (PD)-associated peritonitis is a serious complication of PD, and its prevention and treatment are important for reducing patient morbidity and mortality. Reports of PD-associated peritonitis caused by Corynebacterium spp. are limited, and PD-associated peritonitis caused by Corynebacterium striatum (C. striatum) is rare. Only two case reports are available, wherein improvement was only achieved after intraperitoneal administration of antibiotics. Here, we report a case of relapsing PD-associated peritonitis caused by C. striatum that did not improve with antibiotic therapy. In this case, the patient started PD due to end-stage renal failure with immunoglobulin A nephropathy. In addition, he had been diagnosed with bronchiectasis and was prescribed clarithromycin. Four days after PD induction, the patient developed culture-negative PD-associated peritonitis. Ceftazidime and cefazolin were subsequently administered intraperitoneally for a total of 14 days, resulting in improvement in his condition. However, 3 and 5 months after PD induction, he developed PD-associated peritonitis again, and C. striatum was detected in each culture. He was treated with intraperitoneal vancomycin for a total of 14 days and improved; however, he developed PD-associated culture-negative peritonitis again 7 months later. We diagnosed relapsing PD-associated peritonitis caused by C. striatum. PD catheter removal and reinsertion were performed, and he has not relapsed since. In conclusion, PD-associated peritonitis caused by C. striatum may have a poor prognosis; therefore, PD catheter removal is recommended, especially in patients with a history of repeated PD-related peritonitis due to C. striatum.

Diptheroids can cause nosocomial UTI and be multidrug resistant: A case report of Corynebacterium striatum, first from India

Gram positive bacilli in the urine are usually dismissed as contaminants in urine specimens as these are commensal flora of skin and mucous membranes. Corynebacterium species were misidentified in the past due to complex biochemicals but the advent of modern diagnostics has made their identification quicker and accurate. Corynebacterium species have recently emerged as pathogens of nosocomial outbreak potential. C. striatum has been identified as opportunistic nosocomial pathogen causing various infections. We report first case of C. striatum as nosocomial urinary tract infection (UTI) pathogen in a child with bilateral renal disease. C. striatum causing UTI is very rarely reported.

Infective Endocarditis Caused by Corynebacterium striatum: Navigating Challenges and Treatment Strategies in an Emerging Threat

Corynebacterium striatum is a type of bacteria normally found in the environment and is considered a benign microbe on the human body surface. However, it can induce severe medical conditions, including bacteremia, infective endocarditis, osteomyelitis, and infections, in other organs. This case study focuses on a 56-year-old male patient with multiple comorbidities who presented with an ischemic stroke. Several days after the insertion of a right internal jugular line, the patient developed fever and tachycardia. Blood cultures revealed the presence of Corynebacterium striatum, a Gram-positive bacilli. Transesophageal echocardiography confirmed the diagnosis of complicated infective endocarditis (IE) with mitral valve vegetation and moderate mitral regurgitation. Prompt treatment with appropriate antibiotics, including linezolid and later vancomycin, led to the patient's improvement and eventual discharge in good condition. This case highlights the importance of early recognition, aggressive management, and accurate diagnosis in cases of IE caused by Corynebacterium striatum. Proper antibiotic selection is crucial, considering the emerging antibiotic resistance patterns associated with this pathogen. By addressing these aspects, patient outcomes can be improved, and potential complications such as IE can be prevented.

The Pan-Genomic Analysis of Corynebacterium striatum Revealed its Genetic Characteristics as an Emerging Multidrug-Resistant Pathogen

Corynebacterium striatum is a Gram-positive bacterium that is straight or slightly curved and non-spore-forming. Although it was originally believed to be a part of the normal microbiome of human skin, a growing number of studies have identified it as a cause of various chronic diseases, bacteremia, and respiratory infections. However, despite its increasing importance as a pathogen, the genetic characteristics of the pathogen population, such as genomic characteristics and differences, the types of resistance genes and virulence factors carried by the pathogen and their distribution in the population are poorly understood. To address these knowledge gaps, we conducted a pan-genomic analysis of 314 strains of C. striatum isolated from various tissues and geographic locations. Our analysis revealed that C. striatum has an open pan-genome, comprising 5692 gene families, including 1845 core gene families, 2362 accessory gene families, and 1485 unique gene families. We also found that C. striatum exhibits a high degree of diversity across different sources, but strains isolated from skin tissue are more conserved. Furthermore, we identified 53 drug resistance genes and 42 virulence factors by comparing the strains to the drug resistance gene database (CARD) and the pathogen virulence factor database (VFDB), respectively. We found that these genes and factors are widely distributed among C. striatum, with 77.7% of strains carrying 2 or more resistance genes and displaying primary resistance to aminoglycosides, tetracyclines, lincomycin, macrolides, and streptomycin. The virulence factors are primarily associated with pathogen survival within the host, iron uptake, pili, and early biofilm formation. In summary, our study provides insights into the population diversity, resistance genes, and virulence factors ofC. striatum from different sources. Our findings could inform future research and clinical practices in the diagnosis, prevention, and treatment of C. striatum-associated diseases.

Phylogenetic analyses of antimicrobial resistant Corynebacterium striatum strains isolated from a nosocomial outbreak in a tertiary hospital in China

Corynebacterium striatum is an emerging, multidrug-resistant pathogen that frequently causes nosocomial infections worldwide. This study aimed to investigate phylogenetic relationship and presence of genes responsible for antimicrobial resistance among C. striatum strains associated with an outbreak at the Shanxi Bethune Hospital, China, in 2021. Fecal samples were collected from 65 patients with C. striatum infection at Shanxi Bethune Hospital between February 12, 2021 and April 12, 2021. C. striatum isolates were identified by 16S rRNA and rpoB gene sequencing. E-test strips were used to examine the antimicrobial susceptibility of the isolates. Whole-genome sequencing and bioinformatics analysis were employed to assess the genomic features and identify antimicrobial resistance genes of the isolates. Crystal violet staining was conducted to determine the ability of biofilm formation of each isolate. A total of 64 C. striatum isolates were identified and categorized into 4 clades based on single nucleotide polymorphisms. All isolates were resistant to penicillin, meropenem, ceftriaxone, and ciprofloxacin but susceptible to vancomycin and linezolid. Most isolates were also resistant to tetracycline, clindamycin, and erythromycin, with susceptibility rates of 10.77, 4.62, and 7.69%, respectively. Genomic analysis revealed 14 antimicrobial resistance genes in the isolates, including tetW, ermX, and sul1. Crystal violet staining showed that all isolates formed biofilms on the abiotic surface. Four clades of multidrug-resistant C. striatum spread in our hospitals possibly due to the acquisition of antimicrobial resistance genes.

Prescription of Rifampicin for Staphylococcus aureus Infections Increased the Incidence of Corynebacterium striatum with Decreased Susceptibility to Rifampicin in a Hungarian Clinical Center

Several reports have suggested a role for Corynebacterium striatum as an opportunistic pathogen. The authors have conducted a retrospective study at the Clinical Center of the University of Szeged, Hungary, between 2012 and 2021 that revealed significantly increased rifampicin resistance in this species. This work aimed to investigate the reasons behind this phenomenon. The data were collected corresponding to the period between 1 January 2012 and 31 December 2021 at the Department of Medical Microbiology, University of Szeged. To characterize the resistance trends, the antibiotic resistance index was calculated for each antibiotic in use. Fourteen strains with different resistance patterns were further analyzed with Fourier-transform infrared spectroscopy using the IR Biotyper^®. The decline in C. striatum sensitivity to rifampicin seen during the COVID-19 pandemic may have been attributable to the use of Rifadin^® to treat concomitant Staphylococcus aureus infections. The fact that the IR Biotyper^® typing method revealed that the rifampicin-resistant C. striatum strains were closely related supports this hypothesis. The IR Biotyper^® infrared spectroscopy proved to be a modern and fast method to support effective antimicrobial stewardship programs.

Epidemiological Investigation of Hospital Transmission of Corynebacterium striatum Infection by Core Genome Multilocus Sequence Typing Approach

Corynebacterium striatum has recently received increasing attention due to its multiple antimicrobial resistances and its role as an invasive infection/outbreak agent. Recently, whole-genome sequencing (WGS)-based core genome multilocus sequence typing (cgMLST) has been used in epidemiological studies of specific human pathogens. However, this method has not been reported in studies of C. striatum. In this work, we aim to propose a cgMLST scheme for C. striatum. All publicly available C. striatum genomes, 30 C. striatum strains isolated from the same hospital, and 1 epidemiologically unrelated outgroup C. striatum strain were used to establish a cgMLST scheme targeting 1,795 genes (hereinafter referred to as 1,795-cgMLST). The genotyping results of cgMLST showed good congruence with core genome-based single-nucleotide polymorphism typing in terms of tree topology. In addition, the cgMLST provided a greater discrimination than the MLST method based on 6 housekeeping genes (gyrA, gyrB, hsp65, rpoB, secA1, and sodA). We established a clonal group (CG) threshold based on 104 allelic differences; a total of 56 CGs were identified from among 263 C. striatum strains. We also defined an outbreak threshold based on seven allelic differences that is capable of identifying closely related isolates that could give clues on hospital transmission. According to the results of analysis of drug-resistant genes and virulence genes, we identified CG4, CG5, CG26, CG28, and CG55 as potentially hypervirulent and multidrug-resistant CGs of C. striatum. This study provides valuable genomic epidemiological data on the diversity, resistance, and virulence profiles of this potentially pathogenic microorganism. IMPORTANCE Recently, WGS of many human and animal pathogens has been successfully used to investigate microbial outbreaks. The cgMLST schema are powerful genotyping tools that can be used to investigate potential epidemics and provide classification of the strains precise and reliable. In this study, we proposed the development of a cgMLST typing scheme for C. striatum, and then we evaluated this scheme for its applicability to hospital transmission investigations. This report describes the first cgMLST schema for C. striatum. The analysis of hospital transmission of C. striatum based on cgMLST methods has important clinical epidemiological significance for improving nosocomial infection monitoring of C. striatum and in-depth understanding of its nosocomial transmission routes.

The pan-genome of the emerging multidrug-resistant pathogen Corynebacterium striatum

Corynebacterium striatum, a common constituent of the human skin microbiome, is now considered an emerging multidrug-resistant pathogen of immunocompromised and chronically ill patients. However, little is known about the molecular mechanisms in the transition from colonization to the multidrug-resistant (MDR) invasive phenotype in clinical isolates. This study performed a comprehensive pan-genomic analysis of C. striatum, including isolates from "normal skin microbiome" and from MDR infections, to gain insights into genetic factors contributing to pathogenicity and multidrug resistance in this species. For this, three novel genome sequences were obtained from clinical isolates of C. striatum of patients from Brazil, and other 24 complete or draft C. striatum genomes were retrieved from GenBank, including the ATCC6940 isolate from the Human Microbiome Project. Analysis of C. striatum strains demonstrated the presence of an open pan-genome (α = 0.852803) containing 3816 gene families, including 15 antimicrobial resistance (AMR) genes and 32 putative virulence factors. The core and accessory genomes included 1297 and 1307 genes, respectively. The identified AMR genes are primarily associated with resistance to aminoglycosides and tetracyclines. Of these, 66.6% are present in genomic islands, and four AMR genes, including aac(6')-ib7, are located in a class 1-integron. In conclusion, our data indicated that C. striatum possesses genomic characteristics favorable to the invasive phenotype, with high genomic plasticity, a robust genetic arsenal for iron acquisition, and important virulence determinants and AMR genes present in mobile genetic elements.

Antibioflm effects of extracellular matrix degradative agents on the biofilm of different strains of multi-drug resistant Corynebacterium striatum

BACKGROUND

Corynebacterium striatum is a microorganism with an excellent capacity for biofilm production and thus has been correlated with nosocomial transmission and invasive infections. However, little is known about the mechanism of biofilm formation of this commensal pathogen. In this study, we aimed to investigate the biofilm formation abilities of multidrug-resistant Corynebacterium striatum clinical isolates and the roles of extracellular proteins, exopolysaccharides and extracellular DNA in mediating more robust biofilm formation by the isolates of C. striatum.

METHODS

C. striatum isolates were identified using VITEK-2 ANC card, matrix-assisted laser desorption/ionization-time of flight mass spectrometry and 16S rRNA sequencing. The antibiotic susceptibility test was performed using the broth microdilution method. The distribution of spaDEF genes among C. striatum isolates was detected by polymerase chain reaction, and pulsed-field gel electrophoresis typing was employed to analyze the genotypes of the isolates. Crystal violet staining and scanning electron microscopy techniques were used to detect biofilm production by C. striatum isolates. Biofilm degradation assay was performed to observe the effects of extracellular matrix degradative agents (proteinase K, dispersin B, and DNase I) on C. striatum biofilms.

RESULTS

Twenty-seven C. striatum isolates were enrolled in the study, and the resistance rates were the highest (100%, 27/27) against penicillin and ceftriaxone. Approximately 96.3% (26/27) C. striatum isolates were resistant to at least three different types of antimicrobial agents tested. All isolates were confirmed to be biofilm producers, and 74.07% (20/27) isolates presented moderate to strong biofilm production abilities. P7 genotype (44.4%, 12/27) was identified to as the predominant genotype, and all of isolates belonging to this genotype were multidrug-resistant and had stronger biofilm-forming abilities. Most C. striatum isolates (74.07%, 20/27) carry spaD, spaE, and spaF genes, which encode spa-type pili. However, the correlation between the expression of spa-type genes and the biofilm production abilities of the C. striatum isolates was not found. The biofilms of 80% (8/10), 90% (9/10), and 100% (10/10) C. striatum isolates with moderate to strong biofilm production abilities were significantly eliminated upon the treatment of dispersin B (20 μg/mL), DNase I (20 μg/mL), and proteinase K (20 μg/mL) (p < 0.05), respectively. For the combination groups with two kinds of biofilm-degradative agents, the combination of 20 μg/mL proteinase K/dispersin B showed the strongest biofilm-eliminating effects, when the biofilms of 90% (9/10) C. striatum isolates degraded more than 50%.

CONCLUSIONS

The C. striatum isolates that belonged to the predominant genotype showed a multidrug resistance (MDR) phenotype and strong biofilm formation abilities. Extracellular matrix seems to be an essential determinant in mediating biofilm formation of MDR C. striatum, since extracellular matrix degradative agents (proteinase K, dispersin B and DNase I) showed strong biofilm-eliminating effects toward multidrug-resistant C. striatum isolates. The findings of this study highlight new ideas/directions to explore the whole nature of biofilm formation of C. striatum and the function of extracellular matrix in this process.

Severe Pneumonia Caused by Corynebacterium striatum in Adults, Seoul, South Korea, 2014–2019

Most (70.4%) cases were hospital-acquired, and 51.9% of patients were immunocompromised.

We investigated the proportion and characteristics of severe Corynebacterium striatum pneumonia in South Korea during 2014–2019. As part of an ongoing observational study of severe pneumonia among adult patients, we identified 27 severe C. striatum pneumonia cases. Most (70.4%) cases were hospital-acquired, and 51.9% of patients were immunocompromised. C. striatum cases among patients with severe hospital-acquired pneumonia (HAP) increased from 1.0% (2/200) during 2014–2015 to 5.4% (10/185) during 2018–2019, but methicillin-resistant Staphylococcus aureus (MRSA) infections among severe HAP cases decreased from 12.0% to 2.7% during the same timeframe. During 2018–2019, C. striatum was responsible for 13.3% of severe HAP cases from which bacterial pathogens were identified. The 90-day mortality rates were similarly high in the C. striatum and MRSA groups. C. striatum was a major cause of severe HAP and had high mortality rates. This pathogen is emerging as a possible cause for severe pneumonia, especially among immunocompromised patients.

'Targeting' the search: An upgraded structural and functional repository of antimicrobial peptides for biofilm studies (B-AMP v2.0) with a focus on biofilm protein targets

Bacterial biofilms, often as multispecies communities, are recalcitrant to conventional antibiotics, making the treatment of biofilm infections a challenge. There is a push towards developing novel anti-biofilm approaches, such as antimicrobial peptides (AMPs), with activity against specific biofilm targets. In previous work, we developed Biofilm-AMP, a structural and functional repository of AMPs for biofilm studies (B-AMP v1.0) with more than 5000 structural models of AMPs and a vast library of AMP annotations to existing biofilm literature. In this study, we present an upgraded version of B-AMP, with a focus on existing and novel bacterial biofilm targets. B-AMP v2.0 hosts a curated collection of 2502 biofilm protein targets across 473 bacterial species, with structural protein models and functional annotations from PDB, UniProt, and PubMed databases. The biofilm targets can be searched for using the name of the source organism, and function and type of protein, and results include designated Target IDs (unique to B-AMP v2.0), UniProt IDs, 3D predicted protein structures, PDBQT files, pre-defined protein functions, and relevant scientific literature. To present an example of the combined applicability of both, the AMP and biofilm target libraries in the repository, we present two case studies. In the first case study, we expand an in silico pipeline to evaluate AMPs against a single biofilm target in the multidrug resistant, bacterial pathogen Corynebacterium striatum, using 3D protein-peptide docking models from previous work and Molecular Dynamics simulations (~1.2µs). In the second case study, we build an in silico pipeline to identify candidate AMPs (using AMPs with both anti-Gram positive and anti-Gram negative activity) against two biofilm targets with a common functional annotation in Pseudomonas aeruginosa and Staphylococcus aureus, widely-encountered bacterial co-pathogens. With its enhanced structural and functional capabilities, B-AMP v2.0 serves as a comprehensive resource for AMP investigations related to biofilm studies. B-AMP v2.0 is freely available at https://b-amp.karishmakaushiklab.com and will be regularly updated with structural models of AMPs and biofilm targets, as well as 3D protein-peptide interaction models for key biofilm-forming pathogens.

Corynebacterium spp.: relationship of pathogenic properties and antimicrobial resistance

Corynebacterium spp. are part of the human microbiome, but can cause the development of inflammatory diseases of various localization. Purpose - to evaluate the relationship between pathogenic properties and resistance to antimicrobial drugs (AMD) of Corynebacterium spp. from patients with inflammatory diseases of the respiratory tract. Strains of Corynebacterium spp. isolated from patients with inflammatory diseases of the respiratory tract (99 pcs.) and practically healthy individuals (33 pcs.). Isolates were identified by mass spectrometric method (MALDI-ToFMS), their adhesive and invasive activity on Hep-2 cells, cytopathic effect (CPE) in CHO-K1 cell culture, and resistance to antimicrobial drugs (AMD) were determined. Indicators of adhesion (3.65±0.679(CFU±m)x102/ml), invasion (1.72±0.230 (CFU±m)x102/ml), cytotoxicity (69.1±3.8% of dead CHO-K1 cells ) Corynebasterium spp. strains isolated from patients are higher (p≤0.05) than similar indicators in practically healthy people. 90.9% of isolates from patients had resistance to AMD, in most cases (57.6±4.9%) resistance to only one AMP was noted, less often to two (25.2±4.3%), three or more (8.08±2.7%). According to the results of correlation-regression analysis, pathogenic properties (adhesiveness, invasiveness, cytotoxicity) of Corynebacterium spp. strains isolated from patients are in close direct relationship with resistance to AMD. This indicates the importance of identifying strains of non-diphtheria corynebacteria resistant to AMDs, which, under the influence of developing resistance to AMDs, can increase their pathogenic potential, moving from commensalism to parasitism.

In vitro Studies of Non-Diphtheriae Corynebacterium Isolates on Antimicrobial Susceptibilities, Drug Resistance Mechanisms, and Biofilm Formation Capabilities

Objective

This study aimed to investigate the antimicrobial susceptibilities, drug resistance mechanisms, and biofilm formation capacities of non-diphtheriae Corynebacterium strains isolated from sterile midstream urine of hospitalized patients with clinical urinary tract infections (UTIs).

Methods

A total of 45 non-diphtheriae Corynebacterium isolates were recovered from sterile midstream urine. The available data of 45 patients were collected. Minimum inhibitory concentrations (MICs) of 10 commonly used antibiotics were determined. Meanwhile, the molecular resistance mechanisms of each agent were performed through PCR with specific primers. Moreover, the biofilm formation capability of each isolate on abiotic surfaces was detected with the MTT method.

Results

In this study, the most prevalent three species were C. striatum (15/45, 33.3%), C. glucuronolyticum (9/45, 20.0%) and C. urealyticum (8/45, 17.8%). These three species also accounted for most renal and ureteral calculi cases. Male patients older than 50 years, especially those with underlying diseases, were more susceptible to non-diphtheriae Corynebacterium infection. All the 45 isolates were 100% susceptible to vancomycin and linezolid, but highly resistant to macrolide–lincosamide–streptogramin B (MLSB), fluoroquinolones, tetracyclines and β-lactams with corresponding mechanisms. The detection rate of multidrug–resistant (MDR) non-diphtheriae Corynebacterium is 91.1%. All isolates are able to form biofilm on abiotic surfaces, except those of C. urealyticum, C. tuberculostearicum and C. jeikeium. Isolates of C. glucuronolyticum and C. Striatum possessed the strongest biofilm formation capacity. C. amycolatum could form biofilm, but varied greatly among different isolates.

Conclusion

C. striatum, C. glucuronolyticum and C. urealyticum were the most prevalent species relevant to UTIs. The high occurrence of MDR isolates and high diversities in resistance profiles, and the distinctive abilities of biofilm formation highlighted the urgency for identification to species level. We should pay more attention to the drug resistance profiles of non-diphtheriae Corynebacterium, which would help improve empirical antibiotic therapy and reduce drug resistance transmission.

Corynebacterium striatum-Got Worse by a Pandemic?

The role of Corynebacterium striatum has been demonstrated in different nosocomial infections. An increasing number of publications have demonstrated its virulence in the respiratory tract, especially in the immunosuppressed patient population. The number of these patients has increased significantly during the COVID-19 pandemic. For this reason, we aimed to investigate the prevalence and antimicrobial resistance pattern of this species between 2012 and 2021 at the Clinical Center of the University of Szeged, Hungary. Altogether, 498 positive samples were included from 312 patients during the study period. On the isolates, 4529 antibiotic susceptibility tests were performed. Our data revealed that the prevalence of C. striatum increased during the COVID-19 pandemic, the rise occurred in respiratory, blood culture, and superficial samples. During the study period, the rifampicin resistance significantly increased, but others have also changed dynamically, including linezolid. The species occurred with diverse and changing co-pathogens in the COVID-19 era. However, the increasing rifampicin and linezolid resistance of C. striatum was probably not due to the most commonly isolated co-pathogens. Based on resistance predictions, vancomycin is likely to remain the only effective agent currently in use by 2030.

Corynebacterium striatum Bacteremia during SARS-CoV2 Infection: Case Report, Literature Review, and Clinical Considerations

Bacterial infections, especially those in hospital settings, represent a major complication of COVID-19 patients, complicating management and worsening clinical outcomes. Corynebacterium striatum is a non-diphtheric actinobacterium that has been reported as being the causative agent of several different infections, affecting both immunocompetent and immunocompromised patients. Recently, C. striatum has been recognized as a nosocomial pathogen that is responsible for severe infection in critical patients, as well as in fragile and immunocompromised subjects. C. striatum has been described as the etiological agent of bacteremia, central line infections, and endocarditis. We report a case of a 91-year-old woman who was hospitalized due to SARS-CoV-2 infection, who developed C. striatum bacteremia and died despite antimicrobial therapy and clinical efforts. Furthermore, we discuss C. striatum diagnosis and treatment based on evidence from the scientific literature.

Niclosamide as a Repurposing Drug against Corynebacterium striatum Multidrug-Resistant Infections

Corynebacterium striatum (C. striatum) is an emerging multidrug-resistant (MDR) pathogen associated with nosocomial infections. In this scenario, we screened the antimicrobial activity of the anthelmintic drugs doramectin, moxidectin, selamectin and niclosamide against 20 C. striatum MDR clinical isolates. Among these, niclosamide was the best performing drug against C. striatum. Niclosamide cytotoxicity was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay on immortalized human keratinocyte cells (HaCaT). After 20 h of treatment, the recorded 50% cytotoxic concentration (CC₅₀) was 2.56 μg/mL. The antibacterial efficacy was determined via disc diffusion, broth microdilution method and time-killing. Against C. striatum, niclosamide induced a growth inhibitory area of 22 mm and the minimum inhibitory concentration that inhibits 90% of bacteria (MIC₉₀) was 0.39 μg/mL, exhibiting bactericidal action. The biofilm biomass eradicating action was investigated through crystal violet (CV), MTT and confocal laser scanning microscopy (CLSM). Niclosamide affected the biofilm viability in a dose-dependent manner and degraded biomass by 55 and 49% at 0.39 μg/mL and 0.19 μg/mL. CLSM images confirmed the biofilm biomass degradation, showing a drastic reduction in cell viability. This study could promote the drug-repurposing of the anthelmintic FDA-approved niclosamide as a therapeutic agent to counteract the C. striatum MDR infections.

Multidrug-Resistant Corynebacterium striatum Developed During Treatment of Ommaya Reservoir Infection

Corynebacterium striatum, a common component of the skin and mucosal microbiota of both immunocompetent and immunocompromised individuals, has become an emerging pathogen, colonizing indwelling medical devices and causing infections at multiple sites. A 3-year-old boy with an Ommaya reservoir in the right ventricle and a medical history of grade 3 intraventricular hemorrhage, Hirschsprung disease, catheter-related methicillin-resistant Staphylococcus aureus bacteremia, and congenital central hypoventilation syndrome was hospitalized for Ommaya reservoir infection with C. striatum. He was treated with ampicillin, to which the initial isolate was susceptible. C. striatum may have acquired multiple-drug resistance during the antibiotic treatment due to biofilm production. The Ommaya reservoir was replaced by external ventricular drainage. Cultures of the removed Ommaya reservoir, and cerebrospinal fluid samples grew C. striatum, which was susceptible to meropenem and vancomycin and resistant to other antibiotics. The antibiotic was switched to vancomycin to treat this new multidrug-resistant strain. After 8 days of vancomycin treatment, the cerebrospinal fluid culture obtained by a lumbar puncture was negative for C. striatum. In cases of device-associated infections caused by biofilm-producing bacteria, it is desirable to remove the device as soon as possible.

The challenge of antibiotic selection in prosthetic joint infections due to Corynebacterium striatum: a case report

Background

Corynebacterium striatum is a gram-positive facultative anaerobe found in the environment and human flora that has historically been considered a contaminant. More recently, Corynebacterium striatum has been implicated in human infections, including respiratory infections, endocarditis, and bone and joint infections, particularly those involving hardware or implanted devices.

Case presentation

A 65-year-old man presented for washout of his left total knee arthroplasty following a revision 20 days prior. The patient underwent debridement of his left total knee and revision of the left total femur arthroplasty. Daptomycin was initiated empirically due to a previous rash from vancomycin. Operative tissue cultures grew Staphylococcus haemolyticus, Staphylococcus epidermidis and Corynebacterium striatum. Given concern for daptomycin resistance and the reliability of vancomycin susceptibility, daptomycin was discontinued and vancomycin initiated following a graded challenge. Within a few days, the patient developed a diffuse, blanching, erythematous, maculopapular rash and daptomycin was restarted. Over the next 72 h, his rash progressed and he met criteria for drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Daptomycin was stopped and oral linezolid initiated; rash improved. C. striatum returned with susceptibility to gentamicin, linezolid, vancomycin and daptomycin. Due to concern for adverse effects on long-term linezolid, daptomycin was restarted and was tolerated for 20 days, at which point purulent drainage from incision increased. The patient underwent another arthroplasty revision and washout. Operative cultures from this surgery were again positive for C. striatum. Repeat C. striatum susceptibilities revealed resistance to daptomycin but retained susceptibility to linezolid. Daptomycin was again changed to linezolid. He completed six weeks of linezolid followed by linezolid 600 mg daily for suppression and ultimately opted for disarticulation.

Conclusions

C. striatum has historically been regarded as a contaminant, particularly when grown in tissue culture in the setting of prosthetic joint infection. Based on the available literature and susceptibility patterns, the most appropriate first-line therapy is vancomycin or linezolid. Treatment with daptomycin should be avoided, even when isolates appear susceptible, due to the risk of development of high-level resistance (MIC > 256 µg/mL) and clinical failure.

AMPing Up the Search: A Structural and Functional Repository of Antimicrobial Peptides for Biofilm Studies, and a Case Study of Its Application to Corynebacterium striatum, an Emerging Pathogen

Antimicrobial peptides (AMPs) have been recognized for their ability to target processes important for biofilm formation. Given the vast array of AMPs, identifying potential anti-biofilm candidates remains a significant challenge, and prompts the need for preliminary in silico investigations prior to extensive in vitro and in vivo studies. We have developed Biofilm-AMP (B-AMP), a curated 3D structural and functional repository of AMPs relevant to biofilm studies. In its current version, B-AMP contains predicted 3D structural models of 5544 AMPs (from the DRAMP database) developed using a suite of molecular modeling tools. The repository supports a user-friendly search, using source, name, DRAMP ID, and PepID (unique to B-AMP). Further, AMPs are annotated to existing biofilm literature, consisting of a vast library of over 10,000 articles, enhancing the functional capabilities of B-AMP. To provide an example of the usability of B-AMP, we use the sortase C biofilm target of the emerging pathogen Corynebacterium striatum as a case study. For this, 100 structural AMP models from B-AMP were subject to in silico protein-peptide molecular docking against the catalytic site residues of the C. striatum sortase C protein. Based on docking scores and interacting residues, we suggest a preference scale using which candidate AMPs could be taken up for further in silico, in vitro and in vivo testing. The 3D protein-peptide interaction models and preference scale are available in B-AMP. B-AMP is a comprehensive structural and functional repository of AMPs, and will serve as a starting point for future studies exploring AMPs for biofilm studies. B-AMP is freely available to the community at https://b-amp.karishmakaushiklab.com and will be regularly updated with AMP structures, interaction models with potential biofilm targets, and annotations to biofilm literature.

Clinical Characteristics of Corynebacterium Bacteremia Caused by Different Species, Japan, 2014-2020

Corynebacterium bacteremia is most commonly caused by C. striatum or C. jeikeium.

To determine differences in clinical characteristics of patients with bacteremia caused by Corynebacterium striatum, C. jeikeium, and other species of Corynebacterium, we retrospectively reviewed medical records of patients in Japan who had Corynebacterium bacteremia during January 2014–May 2020. Of the 115 records evaluated, 60 (52%) were cases of true bacteremia and 55 (48%) were cases of contamination. Proportions of true bacteremia cases caused by C. striatum (70%) and by C. jeikeium (71%) were significantly higher than those caused by other species of Corynebacterium (9%). These 2 organisms were commonly detected in blood cultures of patients with hematologic malignancies and neutropenia. The mortality rates at 90 days were 34% (C. striatum), 30% (C. jeikeium), and 0 (other species). Given the high mortality rates, assessing true bacteremia when C. striatum or C. jeikeium is detected in blood cultures, especially in patients with hematologic malignancy, is warranted.

Wide spread and diversity of mutation in the gyrA gene of quinolone-resistant Corynebacterium striatum strains isolated from three tertiary hospitals in China

BACKGROUND

Corynebacterium striatum was confirmed to be an important opportunistic pathogen, which could lead to multiple-site infections and presented high prevalence of multidrug resistance, particularly to quinolone antibiotics. This study aimed to investigate the mechanism underlying resistance to quinolones and the epidemiological features of 410 quinolone-resistant C. striatum clinical strains isolated from three tertiary hospitals in China.

METHODS

A total of 410 C. striatum clinical strains were isolated from different clinical samples of patients admitted to three tertiary teaching hospitals in China. Antibiotic susceptibility testing was performed using the microdilution broth method and pulsed-field gel electrophoresis (PFGE) was used for genotyping. Gene sequencing was used to identify possible mutations in the quinolone resistance-determining regions (QRDRs) of gyrA.

RESULTS

In total, 410 C. striatum isolates were sensitive to vancomycin, linezolid, and daptomycin but resistant to ciprofloxacin. Depending on the antibiotic susceptibility testing results of 12 antimicrobial agents, the 410 C. striatum strains were classified into 12 resistant biotypes; of these, the three biotypes R1, R2, and R3 were dominant and accounted for 47.3% (194/410), 21.0% (86/410), and 23.2% (95/410) of the resistant biotypes, respectively. Mutations in the QRDRs ofgyrA were detected in all quinolone-resistant C. striatum isolates, and 97.3% of the isolates (399/410) showed double mutations in codons 87 and 91 of the QRDRs of gyrA. Ser-87 to Phe-87 and Asp-91 to Ala-91 double mutation in C. striatum was the most prevalent and accounted for 72.2% (296/410) of all mutations. Four new mutations in gyrA were identified in this study; these included Ser-87 to Tyr-87 and Asp-91 to Ala-91 (double mutation, 101 isolates); Ser-87 to Val-87 and Asp-91 toGly-91 (double mutation, one isolate); Ser-87 to Val-87 and Asp-91 to Ala-91 (double mutation, one isolate); and Ser-87 to Ile-87 (single mutation, one isolate). The minimum inhibitory concentration of ciprofloxacin for isolates with double (96.5%; 385/399) and single (72.7%; 8/11) mutations was high (≥ 32 µg/mL). Based on the PFGE typing results, 101 randomly selected C. striatum strains were classified into 50 genotypes (T01-T50), including the three multidrug-resistant epidemic clones T02, T06, and T28; these accounted for 14.9% (15/101), 5.9% (6/101), and 11.9% (12/101) of all genotypes, respectively. The multidrug-resistant T02 clone was identified in hospitals A and C and persisted from 2016 to 2018. Three outbreaks resulting from the T02, T06, and T28 clones were observed among intensive care unit (ICU) patients in hospital C between April and May 2019.

CONCLUSIONS

Quinolone-resistant C. striatum isolates showed a high prevalence of multidrug resistance. Point mutations in the QRDRs of gyrA conferred quinolone resistance to C. striatum, and several mutations in gyrA were newly found in this study. The great clonal diversity, high-level quinolone resistance and increased prevalence among patients susceptible to C. striatum isolates deserve more attention in the future. Moreover, more thorough investigation of the relationship between quinolone exposure and resistance evolution in C. striatum is necessary.

Corynebacterium spp. - problematic pathogens of the human respiratory tract (review of literature)

Corynebacterium spp. - representatives of the normal microflora of the human body, but their role in the development of diseases in both immunocompromised and immunocompetent patients is known. Corynebacterim spp. (C. pseudodiphtheriticum, C. striatum, C. amycolatum, C. accolens, C. argentoratense, etc.) is associated with diseases of the respiratory tract: tracheitis, pharyngitis, rhinosinusitis, bronchitis, etc. They can be transmitted by airborne droplets, household contact, and possibly by hematogenic pathways. Corynebacterim spp. toxins do not produce, but are capable of adhesion and invasion, biofilm formation, production of neuraminidase, hyaluronidase, and hemolysin. It is necessary to take into account not so much the species, but the strain affiliation of isolates of Corynebacterium spp., since among the representatives of one species of non-diphtheria corynebacteria (for example, C. pseudodiphtheriticum), colonizing the respiratory tract, there may be strains that can exhibit not only pathogenic properties, but also probiotic activity. Microbiological diagnostics is based on their quantitative determination in biological material, phenotypic (culture study, test systems for biochemical identification, Vitek 2 automated systems) and genotypic (16SpRNA gene sequencing and rpoB) methods. It is possible to use mass spectrometric analysis (MALDI-ToF-MS). The greatest activity against Corynebacterium spp. in vitro studies preserve vancomycin, teicoplanin, and linezolid. Successful therapy with at least two of the following antimicrobial agents (AMP) has been reported: vancomycin, rifampicin, linezolid, and daptomycin. The sensitivity of isolates of Corynebacterium spp. to AMP is not related to the species, but is due to strain differences, and therefore it is necessary to test each isolated strain. Continuous monitoring of the sensitivity of Corynebacterium spp. strains to AMP is necessary due to the observed variability of these traits. Of particular importance is the identification of multidrug-resistant isolates that are currently considered highly pathogenic. When compiling the review, the databases Scopus, Web of Science, The Cochrane Library, CyberLeninka, RSCI were used.

Treat Me Well or Will Resist: Uptake of Mobile Genetic Elements Determine the Resistome of Corynebacterium striatum

Corynebacterium striatum, a bacterium that is part of the normal skin microbiota, is also an opportunistic pathogen. In recent years, reports of infections and in-hospital and nosocomial outbreaks caused by antimicrobial multidrug-resistant C. striatum strains have been increasing worldwide. However, there are no studies about the genomic determinants related to antimicrobial resistance in C. striatum. This review updates global information related to antimicrobial resistance found in C. striatum and highlights the essential genomic aspects in its persistence and dissemination. The resistome of C. striatum comprises chromosomal and acquired elements. Resistance to fluoroquinolones and daptomycin are due to mutations in chromosomal genes. Conversely, resistance to macrolides, tetracyclines, phenicols, beta-lactams, and aminoglycosides are associated with mobile genomic elements such as plasmids and transposons. The presence and diversity of insertion sequences suggest an essential role in the expression of antimicrobial resistance genes (ARGs) in genomic rearrangements and their potential to transfer these elements to other pathogens. The present study underlines that the resistome of C. striatum is dynamic; it is in evident expansion and could be acting as a reservoir for ARGs.

Biofilm Formation and Antimicrobial Susceptibility of Non-Diphtheria Corynebacterium Strains Isolated from Blood Cultures: First Report from Turkey

Objective

Non-diphtheriae Corynebacterium strains have been recognized as important pathogens after decades of confusion regarding their microbiological classification and clinical significance. The aim of this study was to identify non-diphtheriae Corynebacterium strains and the prevalence of biofilm formation and antimicrobial resistance.

Method

In total, 126 non-diphtheriae Corynebacterium strains were isolated from blood cultures of inpatients with bacteremia in our hospital between January 2015 and January 2020. Blood cultures were analyzed with the Bactec-9120 system. Strains were identified using MALDI-TOF MS (Bruker Daltonics, Germany). Antimicrobial susceptibilities were determined using the Kirby-Bauer disk diffusion method on a Mueller-Hinton agar and evaluated according to EUCAST standards. Biofilm formation was assessed with the Congo Red Agar method.

Results

Corynebacterium striatum and Corynebacterium matruchotii were the most prevalent with 29 and 26 isolates, respectively. Biofilm production was detected in 62.06% (18/29) of C. striatum, in 53.8% (14/26) of C. matruchotii, in 50% (9/18) of Corynebacterium afermentans, 50% (6/12) of Corynebacterium amycolatum, and in 46% (7/15) of Corynebacterium jeikeium strains. Among the five most prevalent strains, we found a high biofilm rate of 54%. The resistance rates to penicillin, clindamycin, ciprofloxacin, rifampicin, tetracycline, and gentamicin were 91.2%, 87.3%, 79.3%, 56.3%, 45.2%, and 39.6%, respectively. All 126 strains were susceptible to vancomycin and linezolid.

Conclusion

Non-diphtheriae Corynebacterium strains isolated from blood cultures of hospitalized patients with bacteremia may have multidrug resistance and the ability to produce biofilm. These results emphasize the importance of identifying strains and determining their antimicrobial susceptibility and biofilm production potential.

Antimicrobial treatment of Corynebacterium striatum invasive infections: a systematic review

The aim of this study was to establish an evidence-based guideline for the antibiotic treatment of Corynebacterium striatum infections. Several electronic databases were systematically searched for clinical trials, observational studies or individual cases on patients of any age and gender with systemic inflammatory response syndrome, harboring C. striatum isolated from body fluids or tissues in which it is not normally present. C. striatum had to be identified as the only causative agent of the invasive infection, and its isolation from blood, body fluids or tissues had to be confirmed by one of the more advanced diagnostic methods (biochemical methods, mass spectrometry and/or gene sequencing). This systematic review included 42 studies that analyzed 85 individual cases with various invasive infections caused by C. striatum. More than one isolate of C. striatum exhibited 100% susceptibility to vancomycin, linezolid, teicoplanin, piperacillin-tazobactam, amoxicillin-clavulanate and cefuroxime. On the other hand, some strains of this bacterium showed a high degree of resistance to fluoroquinolones, to the majority majority of β-lactams, aminoglycosides, macrolides, lincosamides and cotrimoxazole. Despite the antibiotic treatment, fatal outcomes were reported in almost 20% of the patients included in this study. Gene sequencing methods should be the gold standard for the identification of C. striatum, while MALDI-TOF and the Vitek system can be used as alternative methods. Vancomycin should be used as the antibiotic of choice for the treatment of C. striatum infections, in monotherapy or in combination with piperacillin-tazobactam. Alternatively, linezolid, teicoplanin or daptomycin may be used in severe infections, while amoxicillin-clavulanate may be used to treat mild infections caused by C. striatum.

Virulence of clinically relevant multidrug resistant Corynebacterium striatum strains and their ability to adhere to human epithelial cells and inert surfaces

Corynebacterium striatum is a nosocomial pathogen which is increasingly associated with serious infections in both immunocompetent and immunocompromised patients. However, little is known about virulence factors and mechanisms that may enhance the establishment and long-term survival of Corynebacterium striatum. in the hospital environment. In this study, we investigated the ability of 22 multidrug-resistant C. striatum clinical isolates to adhere to human epithelial cells and to produce biofilm on polystyrene plates, glass and various tracheostomy tubes. We also tested the virulence of these strains on the nematode Caenorhabditis elegans. They showed good adhesion to epithelial human cells after 180 min of infection. The 22 C. striatum were able to produce biofilms on positively and negatively charged abiotic surfaces at 37 °C. They were also able to infect and to kill Caenorhabditis elegans after 5 days of infection. The virulence condition was associated with the presence of SpaDEF operon encoding pili in all strains. This study provides new insights on virulence mechanisms that may contribute to the persistence of C. striatum in the hospital environment, increasing the probability of causing nosocomial infections.

Worldwide survey of Corynebacterium striatum increasingly associated with human invasive infections, nosocomial outbreak, and antimicrobial multidrug-resistance, 1976-2020

Corynebacterium striatum is part of microbiota of skin and nasal mucosa of humans and has been increasingly reported as the etiologic agent of community-acquired and nosocomial diseases. Antimicrobial multidrug-resistant (MDR) C. striatum strains have been increasingly related to various nosocomial diseases and/or outbreaks worldwide, including fatal invasive infections in immunosuppressed and immunocompetent patients. Although cases of infections by C. striatum still neglected in some countries, the improvement of microbiological techniques and studies led to the increase of survival of patients with C. striatum nosocomial infections at different levels of magnitude. Biofilm formation on abiotic surfaces contributes for the persistence of virulent C. striatum and dissemination of antimicrobial resistance in hospital environment. Besides that, empirical antibiotic therapy can select multi-resistant strains and transfer intra and interspecies genes horizontally. In this study, a worldwide survey of C. striatum human infections and nosocomial outbreaks was accomplished by the analysis of clinical–epidemiological and microbiological features of reported cases from varied countries, during a 44-year period (1976–2020).

Medical Device Sterilization and Reprocessing in the Era of Multidrug-Resistant (MDR) Bacteria: Issues and Regulatory Concepts

The emergence of multidrug-resistant (MDR) bacteria threatens humans in various health sectors, including medical devices. Since formal classifications for medical device sterilization and disinfection were established in the 1970's, microbial adaptation under adverse environmental conditions has evolved rapidly. MDR microbial biofilms that adhere to medical devices and recurrently infect patients pose a significant threat in hospitals. Therefore, it is essential to mitigate the risk associated with MDR outbreaks by establishing novel recommendations for medical device sterilization, in a world of MDR. MDR pathogens typically thrive on devices with flexible accessories, which are easily contaminated with biofilms due to previous patient use and faulty sterilization or reprocessing procedures. To prevent danger to immunocompromised individuals, there is a need to regulate the classification of reprocessed medical device sterilization. This article aims to assess the risks of improper sterilization of medical devices in the era of MDR when sterilization procedures for critical medical devices are not followed to standard. Further, we discuss key regulatory recommendations for consistent sterilization of critical medical devices in contrast to the risks of disinfection reusable medical devices.

Bone and Joint Infection Involving Corynebacterium spp.: From Clinical Features to Pathophysiological Pathways

Introduction: Corynebacteria represent often-neglected etiological agents of post-traumatic and/or post-operative bone and joint infection (BJI). We describe here clinical characteristics and bacteriological determinants of this condition. Methods: A retrospective cohort study described characteristics, outcome and determinants of treatment failure of all patients with proven Corynebacterium spp. BJI (i.e., ≥2 culture-positive gold-standard samples). Available strains were further characterized regarding their antibiotic susceptibilies, abilities to form early (BioFilm Ring Test®) and mature (crystal violet staining method) biofilms and to invade osteoblasts (gentamicin protection assay). Results: The 51 included BJI were mostly chronic (88.2%), orthopedic device-related (74.5%) and polymicrobial (78.4%). After a follow-up of 60.7 weeks (IQR, 30.1-115.1), 20 (39.2%) treatment failures were observed, including 4 Corynebacterium-documented relapses, mostly associated with non-optimal surgical management (OR 7.291; p = 0.039). Internalization rate within MG63 human osteoblasts was higher for strains isolated from delayed (>3 months) BJI (p < 0.001). Infection of murine osteoblasts deleted for the β1-integrin resulted in a drastic reduction in the internalization rate. No difference was observed regarding biofilm formation. Conclusions: Surgical management plays a crucial role in outcome of BJI involving corynebacteria, as often chronic and device-associated infections. Sanctuarisation within osteoblasts, implicating the β1 cellular integrin, may represent a pivotal virulence factor associated with BJI chronicity.

Resistance to Antiseptics and Disinfectants of Planktonic and Biofilm-Associated Forms of Corynebacterium striatum

Disinfection and antisepsis are of primary importance in controlling nosocomial infections and outbreaks by pathogens expressing multiple resistance to antimicrobial agents (multidrug-resistant [MDR]) used in therapy. Nowadays, infections related to health services (HAIs) due to MDR and multidrug-susceptible (MDS) Corynebacterium striatum should not be underestimated, including patients using invasive medical devices. The virulence potential of C. striatum needs further investigation. Currently, susceptibility profiles of planktonic and/or sessile forms of four C. striatum strains of different pulsed-field gel electrophoresis types were examined as biocides based on the manufacturer's recommendations: 2% glutaraldehyde (GA), 2% peracetic acid (PA), 1% potassium monopersulfate (Virkon^®; VK), 1% sodium hypochlorite (SH), and 70% ethyl alcohol (ET). Time-kill assays using 2% bovine serum albumin (BSA) were performed for evaluation of influence of organic matter on biocides effects. Planktonic forms expressed GA resistance at different levels. C. striatum viability was observed until 2, 4, 20, and 30 min for MDR 2369/II, MDS 1954/IV, MDR 1987/I, and MDS 1961/III strains, respectively. In contrast to GA, the biocides PA, VK24h, SH, and ET had higher effective bacterial mortality. However, storage of VK (48 hr) reduced their biocide activities. Moreover, mature biofilms were produced on abiotic substrates, including steel surfaces. Post-treatment with GA (30 min), survival of sessile forms was ≥100% than planktonic forms of all C. striatum tested strains. Independent of biocides tested, BSA increased the survival of planktonic and sessile forms (p ≤ 0.005). Present data indicated that hospital staff should be aware of dissemination and eradication of HAIs by C. striatum presenting resistance to biocides, including high-level disinfectants, such as GA.

Preliminary in Vitro Studies on Corynebacterium urealyticum Pathogenetic Mechanisms, a Possible Candidate for Chronic Idiopathic Prostatitis?

Corynebacterium urealyticum is a well-known opportunistic uropathogen that can occur with cystitis, pyelonephritis, and urinary sepsis. Although a wide variety of coryneform bacteria have been found from the male genital tract of prostatitis patients, only one clinical case of prostatitis caused by C. urealyticum has been reported. The aim of this study was to evaluate the in vitro tropism of C. urealyticum towards LNCaP (lymph node carcinoma of the prostate) human cells line and the influence of acetohydroxamic acid as an irreversible urease inhibitor on different aspects of its pathogenicity by means of several in vitro tests, such as the determination and analysis of growth curves, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the production of biofilms, and adhesion to LNCaP and HeLa cell lines. Results have brought new pieces of evidence on the in vitro tropism of C. urealyticum for the human prostate cell line LNCaP and the therapeutic use of the irreversible urease inhibitors such as acetohydroxamic acid (AHA), not only as enzyme blockers to facilitate the removal of encrustations but also as modulators of some pathogenic mechanisms. These interesting preliminary data allow us to assert that there is a real possibility that C. urealyticum is a new candidate for chronic idiopathic prostatitis.

Cytokine Levels in the In Vitro Response of T Cells to Planktonic and Biofilm Corynebacterium amycolatum

Unravelling of the interplay between the immune system and non-diphtheria corynebacteria would contribute to understanding their increasing role as medically important microorganisms. We aimed at the analysis of pro- (TNF, IL-1β, IL-6, IL-8, and IL-12p70) and anti-inflammatory (IL-10) cytokines produced by Jurkat T cells in response to planktonic and biofilm Corynebacterium amycolatum. Two reference strains: C. amycolatum ATCC 700207 (R-CA), Staphylococcus aureus ATCC 25923 (R-SA), and ten clinical strains of C. amycolatum (C-CA) were used in the study. Jurkat T cells were stimulated in vitro by the planktonic-conditioned medium (PCM) and biofilm-conditioned medium (BCM) derived from the relevant cultures of the strains tested. The cytokine concentrations were determined in the cell culture supernatants using the flow cytometry. The levels of the cytokines analyzed were lower after stimulation with the BCM when compared to the PCM derived from the cultures of C-CA; statistical significance (p < 0.05) was observed for IL-1β, IL-12 p70, and IL-10. Similarly, planktonic R-CA and R-SA stimulated a higher cytokine production than their biofilm counterparts. The highest levels of pro-inflammatory IL-8, IL-1β, and IL-12p70 were observed after stimulation with planktonic R-SA whereas the strongest stimulation of anti-inflammatory IL-10 was noted for the BCM derived from the mixed culture of both reference species. Our results are indicative of weaker immunostimulatory properties of the biofilm C. amycolatum compared to its planktonic form. It may play a role in the persistence of biofilm-related infections. The extent of the cytokine response can be dependent on the inherent virulence of the infecting microorganism.

From contamination to infective endocarditis-a population-based retrospective study of Corynebacterium isolated from blood cultures

Corynebacterium is a genus that can contaminate blood cultures and also cause severe infections like infective endocarditis (IE). Our purpose was to investigate microbiological and clinical features associated with contamination and true infection. A retrospective population-based study of Corynebacterium bacteremia 2012–2017 in southern Sweden was performed. Corynebacterium isolates were species determined using a matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Patient were, from the medical records, classified as having true infection or contamination caused by Corynebacterium through a scheme considering both bacteriological and clinical features and the groups were compared. Three hundred thirty-nine episodes of bacteremia with Corynebacterium were identified in 335 patients of which 30 (8.8%) episodes were classified as true infection. Thirteen patients with true bacteremia had only one positive blood culture. Infections were typically community acquired and affected mostly older males with comorbidities. The focus of infection was most often unknown, and in-hospital mortality was around 10% in both the groups with true infection and contamination. Corynebacterium jeikeium and Corynebacterium striatum were significantly overrepresented in the group with true infection, whereas Corynebacterium afermentans was significantly more common in the contamination group. Eight episodes of IE were identified, all of which in patients with heart valve prosthesis. Six of the IE cases affected the aortic valve and six of seven patients were male. The species of Corynebacterium in blood cultures can help to determine if a finding represent true infection or contamination. The finding of a single blood culture with Corynebacterium does not exclude true infection such as IE.

Bloodstream and catheter-related infections due to different clones of multidrug-resistant and biofilm producer Corynebacterium striatum

BACKGROUND

Corynebacterium striatum is an emerging multidrug-resistant (MDR) pathogen associated with immunocompromised and chronically ill patients, as well as nosocomial outbreaks. In this study, we characterized 23 MDR C. striatum isolated of bloodstream and catheter-related infections from a hospital of Rio de Janeiro.

METHODS

C. striatum isolates were identified by 16S rRNA and rpoB genes sequencing. The dissemination of these isolates was accomplished by pulsed-field gel electrophoresis (PFGE). All isolates were submitted to antimicrobial susceptibility testing by disk diffusion and by minimum inhibitory concentration using E-test strips methods. Antimicrobial resistance genes were detected by polymerase chain reaction. Quantitative tests were performed on four different abiotic surfaces and the ability to produce biofilm on the surface of polyurethane and silicone catheter was also demonstrated by scanning electron microscopy.

RESULTS

Eleven PFGE profiles were found. The PFGE profile I was the most frequently observed among isolates. Five different MDR profiles were found and all PFGE profile I isolates presented susceptibility only to tetracycline, vancomycin, linezolid and daptomycin. Only the multidrug-susceptible isolate did not show mutations in the quinolone-resistance determinant region (QRDR) of the gyrA gene and was negative in the search of genes encoding antibiotic resistance. The other 22 isolates were positive to resistance genes to aminoglycoside, macrolides/lincosamides and chloramphenicol and showed mutations in the QRDR of the gyrA gene. Scanning electron microscopy illustrated the ability of MDR blood isolate partaker of the epidemic clone (PFGE profile I) to produce mature biofilm on the surface of polyurethane and silicone catheter.

CONCLUSIONS

Genotyping analysis by PFGE revealed the permanence of the MDR PFGE profile I in the nosocomial environment. Other new PFGE profiles emerged as etiologic agents of invasive infections. However, the MDR PFGE profile I was also found predominant among patients with hematogenic infections. The high level of multidrug resistance associated with biofilm formation capacity observed in MDR C. striatum is a case of concern.

Virulence potential of Corynebacterium striatum towards Caenorhabditis elegans

Corynebacterium striatum strains have been increasingly reported as etiological agents of nosocomial infections and outbreaks in industrialized and developing countries. However, there are few studies focused on the virulence potential of C. striatum. A growing body of research supports the use of Caenorhabditis elegans as a model host for investigating the virulence potential of pathogenic bacteria, including corynebacteria. In the present study, chemotaxis behaviour, mortality, and morphological changes were investigated in nematodes infected by four C. striatum strains isolated from different clinical sites, and with different MDR profiles and PFGE types. The results showed chemotaxis of nematodes towards C. striatum. Nematode death (> 60%) was detected from the first day post-infection with all strains tested, but at different levels, independent of biofilm formation on catheter surfaces and differences in growth temperature between nematodes (20 °C) and mammals (37 °C). C. striatum 2369/II multidrug-resistant (MDR; from tracheal aspirate of a patient undergoing endotracheal intubation) and 1961/III multidrug-sensitive (MDS; urine) strains led to 100% mortality in worms. Survival of nematodes was observed until 4 days post-infection with the C. striatum 1954/IV MDS strain isolated from a surgical wound (13%) and 1987/I MDR strain isolated from a patient with a lower respiratory tract infection (39%). The Dar phenotype was observed post-infection with all MDS and MDR strains except 1954/IV. All strains showed the capacity for bagging formation. Star formation was observed only with strains that led to 100% nematode mortality. In conclusion, C. striatum was found to exert virulence for C. elegans. Variations in nematode morphological changes and levels of mortality indicate differences in the virulence potential of C. striatum independent of clinical isolation site, capacity for biofilm formation, and MDR and PFGE profiles.

A Novel Approach to Study the Effect of Ciprofloxacin on Biofilms of Corynebacterium spp. Using Confocal Laser Scanning Microscopy

Non-diphtherial corynebacteria are Gram-positive rods that cause opportunistic infections, what is supported by their ability to produce biofilm on artificial surfaces. In this study, the characteristic of the biofilm produced on vascular and urological catheters was determined using a confocal microscopy for the most frequently involved in infections diphtheroid species. They were represented by the reference strains of Corynebacterium striatum ATCC 6940 and C. amycolatum ATCC 700207. The effect of ciprofloxacin on the biofilm produced by the antibiotic-susceptible C. striatum strain was evaluated using three concentrations of the antimicrobial agent (2 ×, 4 ×, and 6 × the MIC – the Minimum Inhibitory Concentration). The basis for the interpretation of results was the statistical analysis of maximum points readings from the surface comprising a total of 245 areas of the biofilm image under the confocal microscope. It was observed that ciprofloxacin at a concentration equal to 4 × MIC paradoxically caused an enlargement of areas with live bacteria within the biofilm. Biofilm destruction required the application of ciprofloxacin at a concentration higher than 6 × MIC. This suggests that the use of relatively low doses of antimicrobial agents may increase the number of live bacteria within the biofilm, and further facilitate their detachment from the biofilm’s structure thus leading to the spread of bacteria into the bloodstream or to the neighboring tissues. The method of biofilm analysis presented here provides the original and novel approach to the investigation of the diphtheroid biofilms and their interaction with antimicrobial agents.

Mechanism of High-Level Daptomycin Resistance in Corynebacterium striatum

Daptomycin, a last-line-of-defense antibiotic for treating Gram-positive infections, is experiencing clinical failure against important infectious agents, including Corynebacterium striatum The recent transition of daptomycin to generic status is projected to dramatically increase availability, use, and clinical failure. Here we confirm the genetic mechanism of high-level daptomycin resistance (HLDR; MIC = >256 µg/ml) in C. striatum, which evolved within a patient during daptomycin therapy, a phenotype recapitulated in vitro In all 8 independent cases tested, loss-of-function mutations in phosphatidylglycerol synthase (pgsA2) were necessary and sufficient for high-level daptomycin resistance. Through lipidomic and biochemical analysis, we demonstrate that daptomycin's activity is dependent on the membrane phosphatidylglycerol (PG) concentration. Until now, the verification of PG as the in vivo target of daptomycin has proven difficult since tested cell model systems were not viable without membrane PG. C. striatum becomes daptomycin resistant at a high level by removing PG from the membrane and changing the membrane composition to maintain viability. This work demonstrates that loss-of-function mutation in pgsA2 and the loss of membrane PG are necessary and sufficient to produce high-level resistance to daptomycin in C. striatumIMPORTANCE Antimicrobial resistance threatens the efficacy of antimicrobial treatment options, including last-line-of-defense drugs. Understanding how this resistance develops can help direct antimicrobial stewardship efforts and is critical to designing the next generation of antimicrobial therapies. Here we determine how Corynebacterium striatum, a skin commensal and opportunistic pathogen, evolved high-level resistance to a drug of last resort, daptomycin. Through a single mutation, this pathogen was able to remove the daptomycin's target, phosphatidylglycerol (PG), from the membrane and evade daptomycin's bactericidal activity. We found that additional compensatory changes were not necessary to support the removal of PG and replacement with phosphatidylinositol (PI). The ease with which C. striatum evolved high-level resistance is cause for alarm and highlights the importance of screening new antimicrobials against a wide range of clinical pathogens which may harbor unique capacities for resistance evolution.

Factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures

This study aimed to identify clinical or microbiological factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures. A total of 64 isolates from 51 patients identified as C. striatum by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing were assessed. More than two blood cultures were positive in 25 (48.1%) patients. Diabetes, solid tumor, and a history of previous exposure to antibiotics were more common in patients with multiple positive blood cultures. Charlson comorbidity scores were also higher, and more isolates were recovered after 48 hours of hospital stay in patients with multiple positive blood cultures. Strains recovered from patients with multiple positive blood cultures produced significantly more biofilm. Based on multilocus sequence typing (MLST), sequence type (ST) 20 (31.3%) was the most dominant, followed by ST2 (20.3%) and ST23 (10.9%). There was no relationship between the number of positive blood culture sets and sequence typing. In multivariate analyses, Carlson comorbidity score (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.09–3.36; P = 0.03) and biofilm formation were associated with multiple positive blood cultures (OR, 17.43; 95% CI, 3.71–81.91; P = 0.03). This study provides evidence that the biofilm phenotype could contribute to determining the clinical significance of C. striatum in patients with severe underlying conditions. The predominance of certain STs suggests the relatedness of C. striatum infection and the nosocomial environment.

Synergistic Interactions in Microbial Biofilms Facilitate the Establishment of Opportunistic Pathogenic Fungi in Household Dishwashers

Biofilms formed on rubber seals in dishwashers harbor diverse microbiota. In this study, we focussed on the microbial composition of bacteria and fungi, isolated from a defined area of one square centimeter of rubber from four domestic dishwashers and assessed their abilities to in vitro multispecies biofilm formation. A total of 80 isolates (64 bacterial and 16 fungal) were analyzed. Multiple combinations of bacterial isolates from each dishwasher were screened for synergistic interactions. 32 out of 140 tested (23%) four-species bacterial combinations displayed consistent synergism leading to an overall increase in biomass, in all experimental trails. Bacterial isolates from two of the four dishwashers generated a high number of synergistically interacting four-species consortia. Network based correlation analyses also showed higher co-occurrence patterns observed between bacterial members in the same two dishwasher samples, indicating cooperative effects. Furthermore, two synergistic four-species bacterial consortia were tested for their abilities to incorporate an opportunistic fungal pathogen, Exophiala dermatitidis and their establishment as biofilms on sterile ethylene propylene diene monomer M-class (EPDM) rubber and polypropylene (PP) surfaces. When the bacterial consortia included E. dermatitidis, the overall cell numbers of both bacteria and fungi increased and a substantial increase in biofilm biomass was observed. These results indicate a novel phenomenon of cross kingdom synergy in biofilm formation and these observations could have potential implications for human health.

Retrospective evaluation of the clinical characteristics associated with Corynebacterium species bacteremia

Objectives

Corynebacterium spp. are becoming recognized as pathogens that potentially cause various infections. We aimed to evaluate the clinical characteristics associated with Corynebacterium spp. bacteremia.

Patients and methods

We retrospectively reviewed the medical records of all adult patients who had positive blood cultures for Corynebacterium spp. in a single university hospital between January 2014 and December 2016. Patients were divided into a bacteremia group and a contamination group based on microbiological test results and clinical characteristics. Patients’ characteristics, antimicrobial susceptibility of isolated species, antimicrobials administered, and patient outcomes were evaluated.

Results

Corynebacterium spp. were isolated from blood samples of 63 patients; Corynebacterium striatum was the predominant isolate. Twenty-eight patients were determined to have bacteremia. Younger age (p = 0.023), shorter time to positivity (p = 0.006), longer hospital stay (p = 0.009), and presence of an indwelling vascular catheter (p = 0.002) were observed more often in the bacteremia group compared to the contamination group. The source of infection in most patients with bacteremia was an intravenous catheter. All tested strains were susceptible to vancomycin. Four of the 27 patients with bacteremia died, despite administration of appropriate antimicrobial therapy.

Conclusions

We found that younger age, shorter time to positivity, and presence of an indwelling catheter were related to bacteremia caused by Corynebacterium spp. Appropriate antimicrobials should be administered once Corynebacterium spp. are isolated from the blood and bacteremia is suspected.

When Good Bugs Go Bad: Epidemiology and Antimicrobial Resistance Profiles of Corynebacterium striatum, an Emerging Multidrug-Resistant, Opportunistic Pathogen

Infections with Corynebacterium striatum have been described in the literature over the last 2 decades, with the majority being bacteremia, central line infections, and occasionally, endocarditis. In recent years, the frequency of C. striatum infections appears to be increasing; a factor likely contributing to this is the increased ease and accuracy of the identification of Corynebacterium spp., including C. striatum, from clinical cultures. The objective of this study was to retrospectively characterize C. striatum isolates recovered from specimens submitted as part of routine patient care at a 1,250-bed, tertiary-care academic medical center. Multiple strain types were recovered, as demonstrated by repetitive-sequence-based PCR. Most of the strains of C. striatum characterized were resistant to antimicrobials commonly used to treat Gram-positive organisms, such as penicillin, ceftriaxone, meropenem, clindamycin, and tetracycline. The MIC₅₀ for ceftaroline was >32 μg/ml. Although there are no interpretive criteria for susceptibility with telavancin, it appeared to have potent in vitro efficacy against this species, with MIC₅₀ and MIC₉₀ values of 0.064 and 0.125 μg/ml, respectively. Finally, as previously reported in case studies, we demonstrated rapid in vitro development of daptomycin resistance in 100% of the isolates tested (n = 50), indicating that caution should be exhibited when using daptomycin for the treatment of C. striatum infections. C. striatum is an emerging, multidrug-resistant pathogen that can be associated with a variety of infection types.

Comparison of 16S ribosomal RNA gene sequence analysis and conventional culture in the environmental survey of a hospital

Background

Nosocomial infection is one of the most common complications within health care facilities. Certain studies have reported outbreaks resulting from contaminated hospital environments. Although the identification of bacteria in the environment can readily be achieved using culturing methods, these methods detect live bacteria. Sequencing of the 16S ribosomal RNA (16S rRNA) gene is recognized to be effective for bacterial identification. In this study, we surveyed wards where drug-resistant bacteria had been isolated and compared conventional culture methods with 16S rRNA gene sequencing methods.

Methods

Samples were collected using sterile swabs from two wards (northern and southern) at Gunma University Hospital contaminated by Acinetobacter sp.. We extracted DNA directly from the swabs. Following extraction, the DNA was amplified using polymerase chain reaction (PCR). The PCR products were cloned using the plasmid vector. The plasmid DNA were sequenced, and identification were performed using database. 16S rRNA gene sequence analyses were compared conventional culture methods.

Results

In the northern ward, Acinetobacter sp. was detected from only two of 14 samples using the culture method. In contrast, 16S rRNA gene sequencing analysis detected Acinetobacter sp. from seven of 14 samples. Drug-resistant Acinetobacter sp. was isolated from bathrooms of the southern ward and was detected from four of seven samples using the culture method in comparison with six of seven samples by 16S rRNA gene sequencing analysis.

Conclusions

Molecular biological analysis showed a higher sensitivity to detect specific bacteria and detected a greater number of species than the culture method. Our results suggest that 16S rRNA gene sequencing analysis is useful to identify range of contamination which were not found in conventional culture method. When a nosocomial outbreak cannot be adequately controlled, molecular biological analysis may serve as a useful tool for environmental surveys in hospitals.

Rare case of Corynebacterium striatum septic arthritis

Corynebacterium species are aerobic, Gram-positive bacilli that are commensal organisms of skin and mucosal membranes. Although its pathogenicity is well established, Corynebacterium striatum is frequently isolated in cultures and generally regarded as a contaminant. Rarely, this bacterium causes septic arthritis. We present a case of right shoulder joint septic arthritis due to C. striatum in a lung-transplant recipient with end-stage renal disease. A brief review of the literature regarding C. striatum septic arthritis is also a part of this report.

Clinical and bacteriological analyses of bacteremia due to Corynebacterium striatum

BACKGROUND

Corynebacterium striatum was recently recognized as a potential pathogen of various infectious diseases. However, the clinical entity of this microorganism has not been clearly identified. Therefore, we analyzed C. striatum isolates from blood culture and explored their clinical determinants.

METHODS

We reviewed the medical records of all patients from whom C. striatum isolates were recovered from blood culture for analysis of the patients' backgrounds and clinical course including response to antimicrobial therapy and prognosis.

RESULTS

During the 5-year study period (January 2010 to December 2014), 24 C. striatum strains were isolated from blood samples, and the frequency of C. striatum bacteremia increased. The majority of the strains were multidrug resistant. All of the tested strains were susceptible to only vancomycin. The age at onset of C. striatum bacteremia encompassed all adult age groups, and at least one underlying condition was documented in all patients. Thirteen of the 24 patients were cured using appropriate antibiotics (true infection group); however, 11 of the 24 patients were cured using inappropriate antibiotic therapy or no antibiotics (contamination group). Malignancy and neutropenia significantly increased the odds of true C. striatum bloodstream infection.

CONCLUSIONS

The Corynebacterium species is often considered a contaminant when isolated in culture. Instead, particularly when the strain is isolated from blood, the species should be considered clinically relevant and identified to the species level; in addition, antimicrobial susceptibility testing is recommended.