Risk of Bronchial Complications After Lung Transplantation With Respiratory Corynebacteria. Results From a Monocenter Retrospective Cohort Study.

Corynebacterium spp. are associated with respiratory infections in immunocompromised hosts. A link with bronchial complications after lung transplantation (LTx) has been suggested. We aimed to assess the link between respiratory sampling of Corynebacterium spp. and significant bronchial complication (SBC) after LTx. We performed a single center retrospective study. Inclusion of LTx recipients with at least one respiratory Corynebacterium spp. sample (July 2014 to December 2018). Subjects were matched to unexposed LTx recipients. Primary outcome was SBC occurrence after Corynebacterium spp. isolation. Secondary outcomes were Corynebacterium spp. persistent sampling, chronic lung allograft dysfunction (CLAD) onset and all-cause mortality. Fifty-nine patients with Corynebacterium spp. sampling with 59 without isolation were included. Corynebacterium spp. identification was not associated with SBC occurrence (32.4% vs. 21.6%, p = 0.342). Previous SBC was associated with further isolation of Corynebacterium spp. (OR 3.94, 95% CI [1.72-9.05]). Previous SBC and corticosteroids pulses in the last 3 months were the only factors associated with increased risk of Corynebacterium spp. isolation in multivariate analysis. Corynebacterium spp. sampling was significantly associated with CLAD onset (27.1% vs. 6.9%, p = 0.021). Corynebacterium spp. isolation was not associated with SBC but with higher risk of CLAD. Whether CLAD evolution is affected by Corynebacterium spp. eradication remains to be investigated.

A case of infective endocarditis caused by Arthrobacter woluwensis.

Corynebacteria are rare causative agents of infective endocarditis. This is a reported case of a destructive aorto-mitral infective endocarditis caused by Arthrobacter woluwensis. Microbial identification was achieved by 16S rRNA polymerase chain reaction on valve tissue samples. Outcome was favorable after surgical valve replacement and 4-week antibiotic treatment.

Possibilities of practical application of different culture mediums for laboratory diagnostic of diphtheria.

The purpose of the work is to evaluate the cultural and morphological properties of colonies of clinically significant corynebacteria on culture mediums for the isolation of corynebacteria. The study used 9 culture mediums for the isolation of corynebacteria: a culture medium for the isolation of corynebacteria (Corynebacagar); Tellurite-containing blood agars on base - Culture medium № 1 GRM, Culture agar for the cultivation of microorganisms (GRM agar), Culture medium for determining the sensitivity of microorganisms to antibacterial preparations - AGV, culture agar for the cultivation of dry microorganisms (SPA), Clauberg medium II, Hoyle Medium agar (Oxoid), Blood agar base (Conda), Columbia Agar Base (Conda). The work used 7 test strains of microorganisms from the State collections of pathogenic microorganisms - C. diphtheriae biovars gravis, mitis, intermedius, belfanti and subspecies lausannense, C. ulcerans and C.pseudotuberculosis. Studies were carried out in accordance with MUK 4.2.3065-13 «Laboratory diagnosis of diphtheria infection¼. We describe culture-morphological properties of strains on all tested culture mediums the isolation of corynebacteria after 24 and 48 hours of incubation. Analysis of the results on the growth properties of culture mediums showed that all culture mediums had high sensitivity - from dilution 10-7 for all test strains. Colonies of corynebacteria were visually detected on culture mediums after 19-20 hours of cultivation. When cultivating a suspension of corynebacteria from breeding 10-6 on culture mediums, the number of colonies ranged from 95±5 to 120±10. Conclusion. All culture mediums had differential diagnostic properties that ensure the growth of corynebacteria after the day of incubation.

Cell Walls and Membranes of Actinobacteria.

Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.

Beyond diphtheria toxin: cytotoxic proteins of Corynebacterium ulcerans and Corynebacterium diphtheriae.

Diphtheria toxin is one of the best investigated bacterial toxins and the major virulence factor of toxigenic Corynebacterium diphtheriae and Corynebacterium ulcerans strains. However, also diphtheria toxin-free strains of these two species can cause severe infections in animals and humans, indicating the presence of additional virulence factors. In this study, we present a first characterization of two proteins with cytotoxic effect in corynebacteria. A putative ribosome-binding protein (AEG80717, CULC809_00177), first annotated in a genome sequencing project of C. ulcerans strain 809, was investigated in detail together with a homologous protein identified in C. diphtheriae strain HC04 (AEX80148, CDHC04_0155) in this study. The corresponding proteins show striking structural similarity to Shiga-like toxins. Interaction of wild-type, mutant and complementation as well as overexpression strains with invertebrate model systems and cell lines were investigated. Depending on the presence of the corresponding genes, detrimental effects were observed in vivo in two invertebrate model systems, Caenorhabditis elegans and Galleria mellonella, and on various animal and human epithelial and macrophage cell lines in vitro. Taken together, our results support the idea that pathogenicity of corynebacteria is a multifactorial process and that new virulence factors may influence the outcome of potentially fatal corynebacterial infections.

[The problem of decolonization of Staphylococcus aureus nasal carriers from the microbiologist's point of view (review of literature).]

Staphylococcus aureus asymptomatically persists on the nasal mucosa, and also causes serious diseases in carriers (endogenous infection) and in patients in a hospital (nosocomial infection). Decolonization of nasal carriers of S. aureus is an important measure aimed at reducing the incidence of staphylococcal infections. Carriage is a form of nasal dysbiosis, therefore, the effectiveness of antibiotics for the decolonization of carriers, by definition, is low. The review discusses the prospects of using probiotics to restore the nasal microbiota. The commercial production of nasal probiotics has not yet been established, but developments in this direction are being carried out in different countries. The experimental substantiation of the possibility of using corynebacteria and other representatives of the nasal microbiota for the decolonization of staphylococcal carriers is presented, as well as the authors' ideas on how to improve the methods of microbial therapy. In particular, it was proposed to use biofilm probiotics, autoprobiotics, and autovaccines for this purpose.

The C-terminal coiled-coil domain of Corynebacterium diphtheriae DIP0733 is crucial for interaction with epithelial cells and pathogenicity in invertebrate animal model systems.

BACKGROUND: Corynebacterium diphtheriae is the etiologic agent of diphtheria and different systemic infections. The bacterium has been classically described as an extracellular pathogen. However, a number of studies revealed its ability to invade epithelial cells, indicating a more complex pathogen-host interaction. The molecular mechanisms controlling and facilitating internalization of C. diphtheriae still remains unclear. Recently, the DIP0733 transmembrane protein was found to play an important role in the interaction with matrix proteins and cell surfaces, nematode colonization, cellular internalization and induction of cell death. RESULTS: In this study, we identified a number of short linear motifs and structural elements of DIP0733 with putative importance in virulence, using bioinformatic approaches. A C-terminal coiled-coil region of the protein was considered particularly important, since it was found only in DIP0733 homologs in pathogenic Corynebacterium species but not in non-pathogenic corynebacteria. Infections of epithelial cells and transepithelial resistance assays revealed that bacteria expressing the truncated form of C. diphtheriae DIP0733 and C. glutamicum DIP0733 homolog are less virulent, while the fusion of the coiled-coil sequence to the DIP0733 homolog from C. glutamicum resulted in increased pathogenicity. These results were supported by nematode killing assays and experiments using wax moth larvae as invertebrate model systems. CONCLUSIONS: Our data indicate that the coil-coiled domain of DIP0733 is crucial for interaction with epithelial cells and pathogenicity in invertebrate animal model systems.

Orbital implant infection by Corynebacterium amycolatum.

Corynebacterium amycolatum is a saprophyte gram-positive bacillus of the skin flora. It has been linked to diverse infections in immunocompromised patients and also of different types of prostheses. However, to our knowledge, there are no reports on its ability to produce ocular infections or to grow over alloplastic materials for orbital surgery. We present a case of orbital implant exposure including pure isolation of C. amycolatum. The patient was referred for discharge in his socket. After removal of the artificial eye, a large area of implant exposure and signs of chronic infection were observed. A microbiological sample was taken by rubbing the implant with a sterile swab. The sample was cultured and C. amycolatum was identified by phenotypical characterization. Other microbial species were not isolated. Besides being able to adhere to cardiac and joint devices, this case shows that C. amycolatum is a potential infectious agent of orbital prostheses. Pure isolation of C. amycolatum in an ocular sample is extremely rare and suggests an etiological role of this microorganism in an ocular or periocular infection.

Seminal Corynebacterium strains in infertile men with and without leucocytospermia.

This study aimed to identify seminal Corynebacterium strains in infertile men with and without leucocytospermia. Semen samples from 60 infertile men were allocated into two equal groups: semen samples with leucocytospermia and semen samples without leucocytospermia. Semen culture for Corynebacterium species was carried out on Columbia agar medium confirmed by Gram-stained film and biochemical tests followed by analytical profile index biotyping and antibiotic susceptibility. Bacterial isolates were detected in 20/60 semen cultures (33.3%) as Corynebacteria, Staphylococci, Alpha haemolytic streptococci and E. coli. In all, 12/60 (20%) had Corynebacterium positive semen culture, whereas C. seminal was the major isolated species followed by C. amycolatum, C. jekium and C. urealyticum. There was nonsignificant difference between patients with/without Corynebacterium positive culture regarding sperm concentration and normal sperm morphology; however, in positive cultures sperm motility was significantly lower compared with negative cultures. Antimicrobial sensitivity among Corynebacteria strains was highest for vancomycin, rifampicin then imipenem, ampicillin + sulbactam, ciprofloxacin. It is concluded that positive semen cultures for different Corynebacteria species were demonstrated in infertile men, whereas Corynebacterium seminale was the most common isolated species. Vancomycin, rifampicin then imipenem and ampicillin + sulbactam are recommended as sensitive antibiotics.

Molecular commensalism: how oral corynebacteria and their extracellular membrane vesicles shape microbiome interactions.

Historically, the study of microbe-associated diseases has focused primarily on pathogens, guided by Koch's postulates. This pathogen-centric view has provided a mechanistic understanding of disease etiology and microbial pathogenesis. However, next-generation sequencing approaches have revealed a far more nuanced view of the roles various microbes play in disease, highlighting the importance of microbial diversity beyond individual pathogens. This broader perspective acknowledges the roles of host and microbial communities in disease development and resistance. In particular, the concept of dysbiosis, especially within the oral cavity, has gained attention for explaining the emergence of complex polymicrobial diseases. Such diseases often stem from resident microbes rather than foreign pathogens, complicating their treatment and even clouding our understanding of disease etiology. Oral health is maintained through a delicate balance between commensal microbes and the host, with diseases like caries and periodontal disease arising from pathogenic perturbations of this balance. Commensal microbes, such as certain streptococci and Corynebacterium spp., play crucial roles in maintaining oral health through mechanisms involving hydrogen peroxide production and membrane vesicle secretion, which can inhibit pathogenic species and modulate host immune responses. Recent research focused upon the mechanisms of molecular commensalism has expanded our understanding of these key functions of the commensal microbiome, demonstrating their central role in promoting oral health and preventing disease. These abilities represent a largely untapped reservoir of potential innovative strategies for disease prevention and management, emphasizing the need to bolster a symbiotic microbiome that inherently suppresses pathogenesis.

Staphylococcus epidermidis bacteriocin A37 kills natural competitors with a unique mechanism of action.

Many bacteria produce antimicrobial compounds such as lantibiotics to gain advantage in the competitive natural environments of microbiomes. Epilancins constitute an until now underexplored family of lantibiotics with an unknown ecological role and unresolved mode of action. We discovered production of an epilancin in the nasal isolate Staphylococcus epidermidis A37. Using bioinformatic tools, we found that epilancins are frequently encoded within staphylococcal genomes, highlighting their ecological relevance. We demonstrate that production of epilancin A37 contributes to Staphylococcus epidermidis competition specifically against natural corynebacterial competitors. Combining microbiological approaches with quantitative in vivo and in vitro fluorescence microscopy and cryo-electron tomography, we show that A37 enters the corynebacterial cytoplasm through a partially transmembrane-potential-driven uptake without impairing the cell membrane function. Upon intracellular aggregation, A37 induces the formation of intracellular membrane vesicles, which are heavily loaded with the compound and are essential for the antibacterial activity of the epilancin. Our work sheds light on the ecological role of epilancins for staphylococci mediated by a mode of action previously unknown for lantibiotics.

Exploration of the role of the penicillin binding protein 2c (Pbp2c) in inducible ß-lactam resistance in Corynebacteriaceae.

Six genes encoding putative high molecular weight penicillin-binding proteins (Pbp) are present in the genome of the ß-lactam-resistant strain Corynebacterium jeikeium K411. In this study, we show that pbp2c, one of these six genes, is present in resistant strains of Corynebacteriaceae but absent from sensitive strains. The molecular study of the pbp2c locus from C. jeikeium and its heterologous expression in Corynebacterium glutamicum allowed us to show that Pbp2c confers high levels of ß-lactam resistance to the host and is under the control of a ß-lactam-induced regulatory system encoded by two adjacent genes, jk0410 and jk0411. The detection of this inducible resistance may require up to 48 h of incubation, particularly in Corynebacterium amycolatum. Finally, the Pbp2c-expressing strains studied were resistant to all the ß-lactam antibiotics tested, including carbapenems, ceftaroline, and ceftobiprole.

MAS NMR experiments of corynebacterial cell walls: Complementary 1H- and CPMAS CryoProbe-enhanced 13C-detected experiments.

Bacterial cell walls are gigadalton-large cross-linked polymers with a wide range of motional amplitudes, including rather rigid as well as highly flexible parts. Magic-angle spinning NMR is a powerful method to obtain atomic-level information about intact cell walls. Here we investigate sensitivity and information content of different homonuclear 13C13C and heteronuclear 1H15N, 1H13C and 15N13C correlation experiments. We demonstrate that a CPMAS CryoProbe yields ca. 8-fold increased signal-to-noise over a room-temperature probe, or a ca. 3-4-fold larger per-mass sensitivity. The increased sensitivity allowed to obtain high-resolution spectra even on intact bacteria. Moreover, we compare resolution and sensitivity of 1H MAS experiments obtained at 100 kHz vs. 55 kHz. Our study provides useful hints for choosing experiments to extract atomic-level details on cell-wall samples.

Reservoirs of Corynebacterium spp. in the Environment of Dairy Cows.

Although Corynebacterium spp. can be regularly associated with subclinical and clinical mastitis cases in dairy cows, knowledge on their reservoirs in dairy farms is sparse. Therefore, samples were collected at 10 visits with 14 day intervals from bedding material (n = 50), drinking troughs (n = 20), different walking areas (n = 60), cow brushes (n = 8), fly traps (n = 4), the passage to pasture (n = 9) as well as milking liners (n = 80) and milker gloves (n = 20) in one dairy cow farm. Additionally, quarter foremilk samples from all lactating cows (approximately 200) were collected at each visit. All samples underwent microbiological examination and cultured isolates were identified using MALDI-TOF MS. Most Corynebacterium spp. that were cultivated from milk were also isolated from the housing environment and milking-related niches (C. amycolatum, C. confusum, C. stationis, C. variabile, C. xerosis) or from milking-related niches only (C. frankenforstense, C. pilosum, C. suicordis). C. bovis was not cultivated from any environmental niche, while being the dominant species in milk samples. This study demonstrates that many Corynebacterium spp. present in milk samples can also be isolated from the cows' environment. For C. bovis, the most relevant Corynebacterium species with regard to intramammary infections, it indicates that environmental reservoirs are of little relevance.

Functional Genomics Uncovers Pleiotropic Role of Rhomboids in Corynebacterium glutamicum.

The physiological role of ubiquitous rhomboid proteases, membrane-integral proteins that cleave their substrates inside the lipid bilayer, is still ill-defined in many prokaryotes. The two rhomboid genes cg0049 and cg2767 of Corynebacterium glutamicum were mutated and it was the aim of this study to investigate consequences in respect to growth phenotype, stress resistance, transcriptome, proteome, and lipidome composition. Albeit increased amount of Cg2767 upon heat stress, its absence did not change the growth behavior of C. glutamicum during exponential and stationary phase. Quantitative shotgun mass spectrometry was used to compare the rhomboid mutant with wild type strain and revealed that proteins covering diverse cellular functions were differentially abundant with more proteins affected in the stationary than in the exponential growth phase. An observation common to both growth phases was a decrease in ribosomal subunits and RNA polymerase, differences in iron uptake proteins, and abundance changes in lipid and mycolic acid biosynthesis enzymes that suggested a functional link of rhomboids to cell envelope lipid biosynthesis. The latter was substantiated by shotgun lipidomics in the stationary growth phase, where in a strain-dependent manner phosphatidylglycerol, phosphatidic acid, diacylglycerol and phosphatidylinositol increased irrespective of cultivation temperature.

Multi-Omics of Corynebacterium Pseudotuberculosis 12CS0282 and an In Silico Reverse Vaccinology Approach Reveal Novel Vaccine and Drug Targets.

Corynebacterium pseudotuberculosis is an important animal pathogen, which is also able to infect humans. An optimal treatment of infections with this pathogen is not available today and consequently, more research is necessary to understand the infection process. Here, we present a combined -omics and bioinformatics approach to characterize C. pseudotuberculosis 12CS0282. The genome sequence of strain 12CS0282 was determined, analyzed in comparison with the available 130 C. pseudotuberculosis sequences and used as a basis for proteome analyses. In a reverse vaccinology approach, putative vaccine and drug targets for 12CS0208 were identified. Mass spectrometry analyses revealed the presence of multiple virulence factors even without host contact. In macrophage interaction studies, C. pseudotuberculosis 12CS0282 was highly resistant against human phagocytes and even multiplied within human THP-1 cells. Taken together, the data indicate a high pathogenic potential of the strain.

Clinical relevance and antimicrobial susceptibility profile of the unknown human pathogen Corynebacterium aurimucosum.

Introduction. Even though Corynebacterium aurimucosum has been described in 2002, this species has long been underestimated due to the unreliability of conventional identification methods and only a few cases of infections have been reported.Hypothesis/Gap Statement. Little is known about clinical significance and antimicrobial susceptibility profile of this uncommon species.Aim. To evaluate the clinical relevance of C. aurimucosum and its antimicrobial susceptibility profile.Methodology. All C. aurimucosum isolates, collected from 2010 to 2019 in 10 French university hospitals, were retrospectively included. Demographic, clinical and microbiological data were collected for all cases. Antimicrobial susceptibility testing was performed according to the 2019 EUCAST guidelines.Results. Fifty-seven clinical isolates of C. aurimucosum were collected in 57 patients (median age, 65.8 years; male/female sex ratio, 1.1), mostly from urine (28 %), blood culture (28 %) and bone/synovial fluid (19 %) samples. Of them, 14 cases of infection were confirmed, mainly bone and joint infections (50 %) followed by urinary tract infections (UTIs) (21 %), bacteremia (14 %), skin and soft-tissue infections (14 %). C. aurimucosum was recovered in pure culture in 36 % of cases (UTIs and bacteremia) while mixed cultures were observed for other infections. By testing 52 clinical isolates in vitro, this species appeared to be fully susceptible to linezolid and vancomycin while most isolates (>80 %) were susceptible to amoxicillin (MIC90, 2 µg ml-1), gentamicin, tetracycline and rifampicin. Both cefotaxime and ciprofloxacin seemed to have a limited activity (ca. 50 % of susceptible strains). The MIC distribution for ciprofloxacin showed a bimodal profile with a population of highly-resistant strains with MICs >2 µg ml-1. Most isolates (>90 %) were categorized as resistant to penicillin G and clindamycin.Conclusion. C. aurimucosum should be considered as an actual opportunistic pathogen, and treatment with amoxicillin, vancomycin or linezolid should be preferred.

Corynebacteria in Bovine Quarter Milk Samples-Species and Somatic Cell Counts.

In this species differentiation study of Corynebacterium spp. (C. spp.), quarter foremilk samples from 48 farms were included. These were obtained from both clinically healthy cows and those with clinical mastitis. First, all samples were examined cyto-microbiologically and all catalase-positive rods were differentiated using the direct transfer method in MALDI-TOF MS. C. bovis, C. amycolatum, C. xerosis, and five other species were identified with proportions of 90.1%, 7.7%, and 0.8% for the named species, respectively, and 1.4% for the remaining unnamed species. In addition, somatic cell count (SCC) was determined by flow cytometry. Based on this, the isolates were classified into four udder health groups: "latent infection", "subclinical mastitis", "clinical mastitis" and "others". Approximately 90% of isolates of C. bovis and C. amycolatum were from latently and subclinically infected quarters. Of the C. bovis isolates, 5.8% were obtained from milk samples from clinical mastitis, whereas C. amycolatum was not present in clinical mastitis. The distribution of groups in these two species differed significantly. The geometric mean SCC of all species combined was 76,000 SCC/mL, almost the same as the SCC of C. bovis. With 50,000 SCC/mL, the SCC of C. amycolatum was slightly below the SCC of C. bovis. Through the species-level detection and consideration of SCC performed here, it is apparent that individual species differ in terms of their pathogenicity. Overall, their classification as minor pathogens with an SCC increase is confirmed.