Rothia aeria and Rothia dentocariosa as biofilm builders in infective endocarditis.

BACKGROUND: Rothia sp. are Gram-positive bacteria in the class of Actinobacteria that are part of the physiological oral flora. In rare cases, Rothia aeria and Rothia dentocariosa can cause infective endocarditis (IE). The biofilm potential of Rothia in endocarditis is unknown. METHODS: Specimen from two cases of Rothia endocarditis were obtained during cardiac surgery. One of the patients suffered mitral valve IE from Rothia aeria. In the other case, IE of a prosthetic pulmonary valve was caused by Rothia dentocariosa. Fluorescence in situ hybridization (FISH) was used for visualization of microorganisms within heart valve tissues in combination with PCR and sequencing (FISHseq). RESULTS: The two heart valve specimens featured mature biofilms of bacteria that were identified by FISHseq as Rothia aeria and Rothia dentocariosa, respectively. FISH showed in situ biofilms of both microorganisms that feature distinct phenotypes for the first time ex vivo. Both of our reported cases were treated successfully by heart valve surgery and antibiotic therapy using beta-lactam antibiotics. CONCLUSION: The biofilm potential of Rothia sp. must be taken into account. The awareness of Rothia aeria and Rothia dentocariosa as rare but relevant pathogens for infective endocarditis must be raised. Use of biofilm-effective antibiotics in Rothia IE should be discussed.

Rothia spp. infective endocarditis: A systematic literature review.

OBJECTIVE: To describe the epidemiological, clinical, microbiological, and therapeutic features and outcomes of Rothia infective endocarditis (RIE) and extracardiac infections (ECRI). METHODS: We performed a systematic literature review of published cases of RIE and ECRI. RESULTS: After inclusion of a personal case report, 51 cases of RIE and 215 cases of ECRI were reported. Compared with ECRI patients, RIE patients were significantly more often males (80% versus 59%), intravenous drug users (IVDU) (20% versus 3%), immunocompetent (76% versus 31%), and infected with R. dentocariosa (55% versus 13%) but lacked significant differences with regard to median age (45 years [6-79]), rate of orodental abnormalities (33%), and six-month mortality (14%). Following microbiological documentation, RIE was most often treated with a beta-lactam antibiotic alone (39%) for a median duration of six weeks and required surgery in 39% of cases. CONCLUSION: RIE is rare and likely secondary to a dental portal of entry or cutaneous inoculation in IVDU. Its prognosis seems to be favorable.

Ionizing-radiation-resistant Kocuria rhizophila PT10 isolated from the Tunisian Sahara xerophyte Panicum turgidum: Polyphasic characterization and proteogenomic arsenal.

A new strain belonging to the genus Kocuria, designed PT10, was isolated from irradiated roots of the xerophyte Panicum turgidum. Isolate PT10 is a Gram-positive, coccoid, aerobic and ionizing-radiation (IR)-resistant actinobacterium. PT10 has shown an ability to survive under extreme conditions, such as gamma irradiation, desiccation and high concentration of hydrogen peroxide. Phenotypic, chemotaxonomic and comparative genome analyses support the assignment of strain PT10 (LMG 31102 = DSM 108617) as Kocuria rhizophila. The complete genome sequence of PT10 consists of one chromosome (2,656,287 bps), with a 70.7% G + C content and comprises 2481 protein-coding sequences. A total of 1487 proteins were identified by LC-MS/MS profiling. In silico analyses revealed that the proteome of the oxidation-tolerant PT10 possesses several features explaining its IR-resistant phenotype and many adaptive pathways implicated in response to environmental pressures - desiccation, cold, reactive oxygen species and other stressors.

Complete genome analysis of Glutamicibacter creatinolyticus from mare abscess and comparative genomics provide insight of diversity and adaptation for Glutamicibacter.

Bacteria of the genusGlutamicibacterare considered ubiquitous because they can be found in soil, water and air. They have already been isolated from different habitats, including different types of soil, clinical samples, cheese and plants. Glutamicibacter creatinolyticus is a Gram-positive bacterium important to various biotechnological processes, however, as a pathogen it is associated to urinary tract infections and bacteremia. Recently,Glutamicibacter creatinolyticusLGCM 259 was isolated from a mare, which displayed several diffuse subcutaneous nodules with heavy vascularization. In this study, sequencing, genomic analysis ofG. creatinolyticusLGCM 259 and comparative analyseswere performedamong 4representatives of different members of genusfromdifferent habitats, available in the NCBI database. The LGCM 259 strain's genome carries important factors of bacterial virulence that are essential in cell viability, virulence, and pathogenicity. Genomic islands were predicted for 4 members of genusGlutamicibacter,showing ahigh number of GEIs,which may reflect a high interspecific diversity and a possible adaptive mechanism responsible for the survival of each species in its specific niche. Furthermore,G. creatinolyticusLGCM 259 sharessyntenicregions, albeit with a considerable loss of genes, in relation to the other species. In addition,G. creatinolyticusLGCM 259 presentsresistancegenes to 6 differentclasses ofantibiotics and heavy metals, such as: copper, arsenic, chromium and cobalt-zinc-cadmium.Comparative genomicsanalysescouldcontribute to the identification of mobile genetic elements particular to the speciesG. creatinolyticuscompared to other members of genus. The presence of specific regions inG. creatinolyticuscould be indicative of their rolesin host adaptation, virulence, and the characterization ofastrain that affects animals.

Renibacterium salmoninarum iron-acquisition mechanisms and ASK cell line infection: Virulence and immune response.

Renibacterium salmoninarum is the aetiological agent of bacterial kidney disease (BKD) in salmonid farms. This pathogen possesses at least three iron-acquisition mechanisms, but the link between these mechanisms and virulence is unclear. Therefore, this study used RT-qPCR to assess the effects of normal and iron-limited conditions on iron-uptake genes controlled by IdeR and related to iron acquisition in Chilean R. salmoninarum strain H-2 and the type strain DSM20767T . Further evaluated was the in vitro immune-related response of the Atlantic Salmon Kidney (ASK) cell line, derived from the primary organ affected by BKD. R. salmoninarum grown under iron-limited conditions overexpressed genes involved in haemin uptake and siderophore transport, with overexpression significantly higher in H-2 than DSM20767T . These overexpressed genes resulted in higher cytotoxicity and an increased immune response (i.e., TNF-α, IL-1ß, TLR1 and INF-γ) in the ASK cell line. This response was significantly higher against bacteria grown under iron-limited conditions, especially H-2. These observations indicate that iron-acquisition mechanisms are possibly highly related to the virulence and pathogenic capacity of R. salmoninarum. In conclusion, treatments that block iron-uptake mechanisms or siderophore synthesis are attractive therapeutic approaches for treating R. salmoninarum, which causes significant aquaculture losses.

Specific growth inhibitors of Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, and Clavibacter michiganensis subsp. michiganensis.

Plant pathogenic bacteria cause huge yield losses in crops globally. Therefore, finding effective bactericides to these pathogens is an immediate challenge. In this study, we sought compounds that specifically inhibit the growth of Ralstonia solanacearum. As a result, we identified one promising compound, 1-(4-bromophenyl)-6-methoxy-2,3,4,9-tetrahydro-1H-ß-carboline, which inhibited the growth of R. solanacearum (Rs1002) from a pilot library of 376 chemicals provided from RIKEN. We further obtained its structural analogues and assessed their ability to inhibit Rs1002 growth. Then we identified five compounds, named ralhibitins A to E, that specifically inhibit growth of Rs1002 at >5 µg/ml final concentration. The most effective compounds, ralhibitins A, C, and E completely inhibited the growth of Rs1002 at 1.25 µg/ml. In addition, ralhibitins A to E inhibited growth of Xanthomonas oryzae pv. oryzae but not the other bacteria tested at a final concentration of 10 µg/ml. Whereas, ralhibitin E, besides inhibiting R. solanacearum and X. oryzae pv. oryzae, completely inhibited the growth of X. campestris pv. campestris and the Gram-positive bacterium Clavibacter michiganensis subsp. michiganensis at 10 µg/ml. Growth inhibition by these compounds was stable at pH 6-9 and after autoclaving. Because Rs1002 grew in the culture medium in which ralhibitins were incubated with the ralhibitin-insensitive bacteria, the unaffected bacteria may be able to inactivate the inhibitory effect of ralhibitins. These results suggest that ralhibitins might be potential lead compounds for the specific control of phytopathogenic bacteria.

Transcriptome analysis of Brassica juncea var. tumida Tsen responses to Plasmodiophora brassicae primed by the biocontrol strain Zhihengliuella aestuarii.

Mustard clubroot, caused by Plasmodiophora brassicae, is a serious disease that affects Brassica juncea var. tumida Tsen, a mustard plant that is the raw material for a traditional fermented food manufactured in Chongqing, China. In our laboratory, we screened the antagonistic bacteria Zhihengliuella aestuarii against P. brassicae. To better understand the biocontrol mechanism, three transcriptome analyses of B. juncea var. tumida Tsen were conducted using Illumina HiSeq 4000, one from B. juncea only inoculated with P. brassicae (P), one inoculated with P. brassica and the biocontrol agent Z. aestuarii at the same time (P + B), and the other was the control (H), in which P. brassicae was replaced by sterile water. A total of 19.94 Gb was generated by Illumina HiSeq sequencing. The sequence data were de novo assembled, and 107,617 unigenes were obtained. In total, 5629 differentially expressed genes between biocontrol-treated (P + B) and infected (P) samples were assigned to 126 KEGG pathways. Using multiple testing corrections, 20 pathways were significantly enriched with Qvalue ≤ 0.05. The resistance-related genes, involved in the production of pathogenesis-related proteins, pathogen-associated molecular pattern-triggered immunity, and effector-triggered immunity signaling pathways, calcium influx, salicylic acid pathway, reactive oxygen intermediates, and mitogen-activated protein kinase cascades, and cell wall modification, were obtained. The various defense responses induced by the biocontrol strain combatted the P. brassicae infection. The genes and pathways involved in plant resistance were induced by a biocontrol strain. The transcriptome data explained the molecular mechanism of the potential biocontrol strain against P. brassicae. The data will also serve as an important public information platform to study B. juncea var. tumida Tsen and will be useful for breeding mustard plants resistant to P. brassicae.

Comparative Genomic Analyses of Clavibacter michiganensis subsp. insidiosus and Pathogenicity on Medicago truncatula.

Clavibacter michiganensis is the most economically important gram-positive bacterial plant pathogen, with subspecies that cause serious diseases of maize, wheat, tomato, potato, and alfalfa. Much less is known about pathogenesis involving gram-positive plant pathogens than is known for gram-negative bacteria. Comparative genome analyses of C. michiganensis subspecies affecting tomato, potato, and maize have provided insights on pathogenicity. In this study, we identified strains of C. michiganensis subsp. insidiosus with contrasting pathogenicity on three accessions of the model legume Medicago truncatula. We generated complete genome sequences for two strains and compared these to a previously sequenced strain and genome sequences of four other subspecies. The three C. michiganensis subsp. insidiosus strains varied in gene content due to genome rearrangements, most likely facilitated by insertion elements, and plasmid number, which varied from one to three depending on strain. The core C. michiganensis genome consisted of 1,917 genes, with 379 genes unique to C. michiganensis subsp. insidiosus. An operon for synthesis of the extracellular blue pigment indigoidine, enzymes for pectin degradation, and an operon for inositol metabolism are among the unique features. Secreted serine proteases belonging to both the pat-1 and ppa families were present but highly diverged from those in other subspecies.

Multiple plasmid-borne virulence genes of Clavibacter michiganensis ssp. capsici critical for disease development in pepper.

Clavibacter michiganensis ssp. capsici is a Gram-positive plant-pathogenic bacterium causing bacterial canker disease in pepper. Virulence genes and mechanisms of C. michiganensis ssp. capsici in pepper have not yet been studied. To identify virulence genes of C. michiganensis ssp. capsici, comparative genome analyses with C. michiganensis ssp. capsici and its related C. michiganensis subspecies, and functional analysis of its putative virulence genes during infection were performed. The C. michiganensis ssp. capsici type strain PF008 carries one chromosome (3.056 Mb) and two plasmids (39 kb pCM1Cmc and 145 kb pCM2Cmc ). The genome analyses showed that this bacterium lacks a chromosomal pathogenicity island and celA gene that are important for disease development by C. michiganensis ssp. michiganensis in tomato, but carries most putative virulence genes in both plasmids. Virulence of pCM1Cmc -cured C. michiganensis ssp. capsici was greatly reduced compared with the wild-type strain in pepper. The complementation analysis with pCM1Cmc -located putative virulence genes showed that at least five genes, chpE, chpG, ppaA1, ppaB1 and pelA1, encoding serine proteases or pectate lyase contribute to disease development in pepper. In conclusion, C. michiganensis ssp. capsici has a unique genome structure, and its multiple plasmid-borne genes play critical roles in virulence in pepper, either separately or together.

In Vitro Antibacterial Activity of Pomegranate Juice and Peel Extracts on Cariogenic Bacteria.

AIM: To evaluate the antimicrobial activity of hydroalcoholic extracts of pomegranate (Punica granatum L.) peel and juice, against the microorganisms considered the main etiologic agents of dental caries. METHODS: The values of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined against Streptococcus mutans Clarke ATCC® 25175™ strain and Rothia dentocariosa clinical isolate. RESULTS: Peel extracts inhibit effectively the growth and survival of S. mutans ATCC 25175 strain and R. dentocariosa clinical isolate with MIC and MBC values of 10 µg/µl and 15 µg/µl, respectively. Furthermore, the pomegranate juice extract showed high inhibitory activity against S. mutans ATCC 25175 strain with a MIC value of 25 µg/µl and a MBC value of 40 µg/µl, whereas, against R. dentocariosa, it has displayed a moderate inhibitory activity, with MIC and MBC values of 20 µg/µl and 140 µg/µl, respectively. CONCLUSIONS: In vitro microbiological tests demonstrate that the hydroalcoholic extracts of pomegranate juice and peel are able to contrast the main cariogenic bacteria involved in tooth decay. Although being preliminary data, our results suggest that pomegranate polyphenolic compounds could represent a good adjuvant for the prevention and treatment of dental caries.

Rothia mucilaginosa bacteraemia in an immunocompetent paediatric patient: a new pathogen to take into account. A case report.

Rothia mucilaginosa, previously known as Stomatococcus mucilaginosus, is a Gram-positive coccus that is part of the oropharyngeal microbiota and upper respiratory tract. It is mainly related to infections in immunosuppressed patients. Given its complex microbiological identification, its prevalence may be underestimated. We describe in this article a case of bacteraemia by Rothia in an immunocompetent paediatric patient without epidemiological or medical relevant history. In the available literature no cases of bacteraemia by Rothia mucilaginosa in immunocompetent paediatric patients have been reported. Given the characteristics of our patient, the publication of this case is of interest. Once the diagnosis of Rothia mucilaginosa has been made, the correct functioning of the immune system of the patient should be checked.

Kocuria rosea, kocuria kristinae, leuconostoc mesenteroides as caries-causing representatives of oral microflora.

INTRODUCTION: Recently, opportunistic microflora are increasingly known to be involved in the development of pathological processes in various systems and organs. This situation promotes interest in their detailed study as causative agents of bacterial infections. THE AIM: To study the microbial species residing in carious cavities in acute profound caries. MATERIALS AND METHODS: The study involved 14 people with a diagnosis of acute profound caries. Microbiological methods included determining species of microorganisms' cultures from carious cavities in acute profound caries. Final identification was carried out by automatic bacteriological analyzer Vitec-2compact bioMérieux. CONCLUSION: Among the bacteria isolated, Kocuria rosae, Kocuria kristinae, and Leuconostoc mesenteroides are the focus of the authors' attention due to their identification rate in the patients. These microbial species are little studied due to the lack of data on their cariogenic associations.The meticulous study of the microorganisms, isolated from carious cavities in patients with acute profound caries by automatic bacteriological analyzer Vitec-2 Systems bioMérieux, and findings on their biochemical properties allow us to conclude that Kocuria rosae, Kocuria kristinae, and Leuconostoc mesenteroides are among the microorganisms making up the microflora of carious cavities under acute profound caries and are involved in the development of the caries process.

A virulent clone of Devriesea agamarum affects endangered Lesser Antillean iguanas (Iguana delicatissima).

Infectious diseases affecting wildlife are drivers of global biodiversity loss. Here we report a bacterial threat to endangered wild reptiles. Since April 2011, a severe skin disease has affected free-ranging, endangered Lesser Antillean iguanas (Iguana delicatissima) on the French Caribbean island of Saint Barthélemy and we identified Devriesea agamarum as the causative agent. The presence of this bacterium was also demonstrated in healthy lizards (anoles) co-inhabiting the island. All isolates from the iguanas corresponded to a single AFLP genotype that until now has exclusively been associated with infections in lizard species in captivity. The clonal relatedness of the isolates and recent emergence of the disease suggest recent arrival of a virulent D. agamarum clone on the island. The presence of healthy but infected lizards suggests the presence of asymptomatic reservoir hosts. This is the first description of a bacterial disease that poses a conservation threat towards free-ranging squamates.

Characterization and Comparison of Clavibacter michiganensis subsp. nebraskensis Strains Recovered from Epiphytic and Symptomatic Infections of Maize in Iowa.

Clavibacter michiganensis subsp. nebraskensis (Cmn), the causal organism of Goss's wilt and leaf blight of maize, can be detected in the phyllosphere of its host prior to disease development. We compared the morphology and pathogenicity of 37 putative isolates of Cmn recovered from asymptomatic and symptomatic maize leaves. Thirty-three of the isolates produced mucoid orange colonies, irrespective of the source of isolation and all but four of these isolates were pathogenic on maize. The remaining 4 isolates recovered from asymptomatic leaves had large fluidal yellow colonies, and were non-pathogenic on maize. Isolates varied in their aggressiveness on a susceptible hybrid of maize but no significant differences in aggressiveness were detected between epiphytic isolates and those recovered from diseased maize tissues. The genomics of Cmn is poorly understood; therefore as a first step to determining what genes may play a role in virulence, we compared 33 putative virulence gene sequences from 6 pathogenic and a non-pathogenic isolate recovered from the phyllosphere. Sequence polymorphisms were detected in 5 genes, cellulase A, two endoglucanases, xylanase B and a pectate lyase but there was no relationship with pathogenicity. Further research is needed to determine what genes play a role in virulence of Cmn. Our data show however, that the virulence factors in Cmn likely differ from those reported for the closely related subspecies michiganensis and sepedonicus.

Occupancy modeling for improved accuracy and understanding of pathogen prevalence and dynamics.

Most pathogen detection tests are imperfect, with a sensitivity < 100%, thereby resulting in the potential for a false negative, where a pathogen is present but not detected. False negatives in a sample inflate the number of non-detections, negatively biasing estimates of pathogen prevalence. Histological examination of tissues as a diagnostic test can be advantageous as multiple pathogens can be examined and providing important information on associated pathological changes to the host. However, it is usually less sensitive than molecular or microbiological tests for specific pathogens. Our study objectives were to 1) develop a hierarchical occupancy model to examine pathogen prevalence in spring Chinook salmon Oncorhynchus tshawytscha and their distribution among host tissues 2) use the model to estimate pathogen-specific test sensitivities and infection rates, and 3) illustrate the effect of using replicate within host sampling on sample sizes required to detect a pathogen. We examined histological sections of replicate tissue samples from spring Chinook salmon O. tshawytscha collected after spawning for common pathogens seen in this population: Apophallus/echinostome metacercariae, Parvicapsula minibicornis, Nanophyetus salmincola/ metacercariae, and Renibacterium salmoninarum. A hierarchical occupancy model was developed to estimate pathogen and tissue-specific test sensitivities and unbiased estimation of host- and organ-level infection rates. Model estimated sensitivities and host- and organ-level infections rates varied among pathogens and model estimated infection rate was higher than prevalence unadjusted for test sensitivity, confirming that prevalence unadjusted for test sensitivity was negatively biased. The modeling approach provided an analytical approach for using hierarchically structured pathogen detection data from lower sensitivity diagnostic tests, such as histology, to obtain unbiased pathogen prevalence estimates with associated uncertainties. Accounting for test sensitivity using within host replicate samples also required fewer individual fish to be sampled. This approach is useful for evaluating pathogen or microbe community dynamics when test sensitivity is <100%.

Rothia mucilaginosa pneumonia: a literature review.

BACKGROUND: Rothia mucilaginosa, a gram-positive coccus member of the family Micrococcaceae, is considered part of the normal microflora of the human mouth and the upper respiratory tract. Although this organism is believed to be of low virulence, it is increasingly recognized as an opportunistic pathogen mostly affecting immunocompromised hosts. METHODS: The medical literature was reviewed and we found 19 published cases of R. mucilaginosa pneumonia. We also report on a case of pneumonia attributed to this microorganism in a patient with chronic obstructive pulmonary disease (COPD). RESULTS: From January 1970 to August 2014, a total of 20 patients with R. mucilaginosa pneumonia were studied. Patients with haematologic malignancies (7/20), profoundly neutropenic with central line catheters (7/20) are at higher risk of developing the infection, while immunocompetent hosts with impaired pulmonary defences are less frequently affected (4/20). Beta-lactams or vancomycin alone or in combination with other antibiotics have been successfully used for the treatment of R. mucilaginosa pneumonia. The outcome was favourable in 18 cases. Only one fatality was attributed to the infection. CONCLUSION: R. mucilaginosa should be considered in the diagnosis of pneumonia in both immunocompromised and immunocompetent hosts. Early diagnosis and timely administration of appropriate antibiotic treatment are necessary for cure.

Kocuria species peritonitis: although rare, we have to care.

Kocuria species are found in the environment and on human skin. These micro-organisms are generally considered to be nonpathogenic saprophytes, rarely causing infection. However, the peritoneum has been reported to be a site of Kocuria infection. We reviewed all cases of peritonitis in peritoneal dialysis (PD) patients caused by Kocuria species that were reported in the worldwide literature. In total, 12 episodes of Kocuria species peritonitis have been reported in 9 PD patients. The median age of the patients was 62 years (range: 8 - 78 years). In the reported episodes, 4 different Kocuria species were isolated, with K. varians being the predominant species (41.7%). The most common initial symptom was abdominal pain (83.3%), followed by turbid effluent (75%) and fever (33.3%). Intraperitoneal first-generation cephalosporins and glycopeptides were the most-used antibiotics, with first-generation cephalosporins being more often preferred as first-line therapy. The median duration of treatment was 14 days, and in 2 episodes, the Tenckhoff catheter was removed. Although Kocuria peritonitis in PD patients is rare, it should be promptly treated because relapses can occur, especially with K. varians episodes.