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PubMed1996

An initial appraisal of the clinical significance of Roseomonas species associated with human infections.

We reviewed laboratory, clinical, and epidemiologic data on 35 patients from whom organisms belonging to the genus Roseomonas, a pink-pigmented gram-negative coccobacillus, were isolated over a 22-year period (1972-1994). Roseomonas strains were most commonly isolated from middle-aged women with one of several underlying conditions, including cancer and diabetes. Roseomonas was most commonly isolated from the blood, in association with clinical signs of sepsis. Approximately 60% of all isolates were judged to be of possible clinical significance, either as primary or secondary pathogens; 75% of all strains were recovered in pure culture. Roseomonas gilardii was the most frequently isolated species and was significantly associated with septicemia and underlying immunocompromised conditions; the species of 29% of all Roseomonas isolates could not be unequivocally identified with presently available differential tests. Genomospecies 5, currently an unnamed taxon within the genus Roseomonas, was primarily recovered as a commensal from young adults attending a sexually transmitted diseases clinic. The findings suggest that although this genus appears to have an overall low pathogenic potential for humans, Roseomonas species-in particular, R. gilardii-may be significant pathogens in persons with underlying medical complications.

Adolescent↗
PubMed1996

Detection of pathogenic Yersinia enterocolitica in environmental waters by PCR.

The isolation of pathogenic strains of Yersinia enterocolitica from food and water samples by culture is time-consuming and unreliable. A two-step PCR procedure has been developed which, after a period of bacterial enrichment, can detect and confirm the presence of pathogenic Y. enterocolitica within a single day. This PCR method works effectively for a range of environmental water types, including reticulated waters, reservoirs and creeks. A survey of environmental waters in Victoria, Australia, showed that the PCR method detected pathogenic Y. enterocolitica in water sampled from four separate sites (two creeks and two reservoirs). Repeat samplings of the two reservoirs yielded PCR-positive results on all but one occasion. Culture analysis of the same samples detected pathogenic Y. enterocolitica in only one sample, indicating that the PCR can detect pathogenic Y. enterocolitica which are undetectable by culture. Results from this study confirm that potentially pathogenic strains of Y. enterocolitica can exist in environmental waters.

Base Sequence↗
PubMedDate not supplied

Latest developments in the enzyme-linked immunosorbent assay (ELISA).

Enzyme-linked immunosorbent assays (ELISAs) for the serologic detection of both antigen and antibody in monitoring programs of commercial poultry flocks have begun to be recognized as an improvement over more conventional diagnostic procedures. The feasibility of employing double-antibody sandwich assays for the detection of virus without prior isolation of virus has been demonstrated and shows promise as the method of choice for the detection of lymphoid leukosis virus shedding. The versatility of indirect ELISA for the measurement of antibody induced by a wide variety of potential pathogens using a single basic overlapping ELISA system has also been demonstrated. It shows potential as a likely candidate to replace some of the more costly and time-consuming or less sensitive conventional serologic methods that do not overlap. Although some aspects of the two major types of immunoassays currently used in poultry health may need some modifications or improvements before delivery for routine use, it is likely that the use of computer-assisted ELISA will gain increased acceptance and use as the preferred way to efficiently and accurately monitor the health of poultry flocks on a broad scale.

Animals↗
PubMed1995

The simian herpesviruses.

Increased use of monkeys in biomedical research has led to an intensified awareness of potential dangers posed by zoonotic infections. Zoonoses have an impact not only upon human health and safety but also upon continued availability of nonhuman primate resources for the biomedical community. Neurotropic herpesviruses indigenous to primates are significant owing to their potential for causing severe or fatal infections when transmitted between human and nonhuman primates or between different species of monkeys. Although the macaque herpesvirus (B virus) is known to many investigators, other simian herpesviruses have remained relatively obscure in spite of reports of disease-causing potential. In this review we summarize what is known about the natural history and pathogenic potential of simian alpha-herpesviruses. Recent research into the molecular biology of this group of viruses is also reviewed, and recent advances toward development of diagnostic tests based on these data are discussed.

Animals↗
PubMed1994

Reduction of oral microbes by a single chlorhexidine rinse.

Because of the continued threat of human immunodeficiency virus and hepatitis B infection, as well as the possibility of cross-infection from microbes, such as the herpesviruses and staphylococci, infection control remains a critical issue in dentistry. A traditional response to the infection-control issue is the use of barrier protection by the practitioner and staff. Little attention has been paid to reducing the number of potential pathogens in the oral cavity before dental procedures as a means of minimizing the potential spread of contagion between patients and treatment providers. A study to determine the effectiveness and duration of a single rinse with 0.12% chlorhexidine gluconate oral antiseptic in reducing the number of microorganisms in the oral cavity is presented.

Bacteria, Aerobic↗
PubMed2026

Deciphering the genomic landscape of novel Acinetobacter non-baumannii lineages causing neonatal septicemia: carbapenem resistance and virulence.

BACKGROUND: Acinetobacter non-baumannii (Anb) species are reported worldwide to cause infections in both adults and neonates, although less frequently than Acinetobacter baumannii. However, limited information is available on their genomic diversity, resistance mechanisms, and virulence potential. This study investigates novel Anb isolates causing neonatal septicemia in India to characterize their resistance and pathogenic traits. METHODS: Anb isolates from neonatal blood cultures (2007-2025) were identified by VITEK2 Compact system, MALDI-TOF MS, and Whole-genome sequencing (WGS). Antimicrobial susceptibility was tested by VITEK2. Genomic analysis included MLST, resistome, virulome, plasmid typing, integrons, and core-genome phylogeny analysis. In vitro and in vivo studies assessed pathogenic potential of Anb species. RESULTS: Anb infections were low (11%) among the neonates during the study period. WGS revealed 11 novel Sequence Types (STs) which include A. indicus, A. variabilis, A. schindleri, and A. bereziniae. Six out of these eleven Anbs harbored carbapenemases such as bla NDM-1 and/or bla OXA-58-like genes (bla OXA-58, bla OXA-420). bla NDM-1 was acquired via Tn125 transposon. ISAba125 was located upstream of bla NDM-1, and a conserved structure extending to IS91 family transposase was detected in bla NDM-1-harboring genomes. bla OXA-58-like genes were found to be associated with ISAba3. Most carbapenemases were likely located on chromosome. Class 1 integrons carrying multiple antimicrobial resistance genes (ARGs) and diverse plasmid replicase families were detected in Anbs. Core genome phylogeny showed that the study Anbs were not closely related to the global Anbs. In vitro virulence-associated assays (biofilm formation, surface motility, adherence/invasion, apoptosis) and in vivo lethality in murine infection model showed reduced pathogenicity, reinforcing earlier observations that Anb species are generally less virulent than A. baumannii. Several virulence factors (VFs) were detected; however, no clear correlation was observed between virulence genes, in vitro pathogenicity, and in vivo lethality. CONCLUSION: These results indicate the multifactorial nature of Anb pathogenicity and the current limitations of knowledge of its VFs. However, the presence of numerous VFs suggests a capacity to cause disease, particularly in vulnerable host populations such as neonates. Furthermore, the presence of multiple ARGs indicates a strong potential for persistence and dissemination in hospital environments with high antibiotic pressure. Overall, these findings underscore the importance of continued AMR surveillance, genome characterization and further investigations into Anb pathogenicity.

Acinetobacter non-baumannii↗
PubMed2006

Use of multiparameter analysis for Vibrio alginolyticus viable but nonculturable state determination.

BACKGROUND: Vibrio alginolyticus is known to enter into a viable but nonculturable (VBNC) state in response to environmental conditions unfavorable to the growth. Cells in VBNC condition pose a public health threat because they are potentially pathogenic. METHODS: We constructed a pathway for the identification of the most significant variables and the characterization of those variables able to discriminate the groups under investigation. Different parameters measured by the image processing software were chosen as the most representative of V. alginolyticus cell morphology (length index for dimension) and metabolic activity (density profile indexes). To detect relationships between the groups of treatment performed, we carried out a principal components analysis (PCA). RESULTS: The PCA analysis indicated that increasing coccoid shape transformation was related to both metabolic and dimension variations, delineating a well defined graph profile. Indeed, we discovered that specific morphological variations occur when cells in the culturable state pass into VBNC condition, namely comma-shaped culturable bacteria are converted into coccoid-shaped VBNC cells. The results were also supported by scanning electron microscopy analysis. CONCLUSIONS: This technique allows the analysis of a large number of vibrio samples in a short period of time. The obtained multiparameter information may complement genetic/molecular analyses facilitating, in an automatic fashion, further studies to evaluate the potential risk of this pathogen in the environment. It may also be a useful tool for large-scale cell biology studies and high content screening.

Bacterial Physiological Phenomena↗
PubMed2001

Plant pathogens and integrated defence responses to infection.

Plants cannot move to escape environmental challenges. Biotic stresses result from a battery of potential pathogens: fungi, bacteria, nematodes and insects intercept the photosynthate produced by plants, and viruses use replication machinery at the host's expense. Plants, in turn, have evolved sophisticated mechanisms to perceive such attacks, and to translate that perception into an adaptive response. Here, we review the current knowledge of recognition-dependent disease resistance in plants. We include a few crucial concepts to compare and contrast plant innate immunity with that more commonly associated with animals. There are appreciable differences, but also surprising parallels.

Animals↗
PubMed2001

A murine monoclonal anti-idiotype to anti-ribosomal P antibodies: production, characterization, and use in systemic lupus erythematosus.

Overt anti-ribosomal P (anti-P) autoantibodies are restricted to a subset of systemic lupus erythematosus (SLE) patients, and are potentially pathogenic. Covert anti-P are detected in all other individuals. An idiotype (Id) network is nonoperational in those with overt anti-P, whereas it is functional in all others. The aim of this study was to produce a murine monoclonal (mAb) anti-Id to characterize the anti-P Id network in SLE. BALB/c mice were immunized with F(ab')(2) fragments of IgG anti-P from a patient with a broadly cross-reactive Id. One mAb was chosen (mAb41) that reacted preferentially to the immunogen. This IgG1 mAb bound comparably in ELISAs to affinity-purified anti-P from 11 SLE patients with overt anti-P. This binding was partially inhibited with ribosomal P antigen. In contrast, it did not bind to affinity-purified control autoantibodies, nor to normal human IgG. mAb41 inhibited anti-P binding to ribosomal P antigen in immunoassays and on Jurkat cells. No change was detected in patients' anti-P antibodies over time when mAb41 was used in Id-specific ELISAs. We conclude that mAb41 is an anti-Id that recognizes a public idiotope within the antigen-combining site of anti-P antibodies. Thus, it is analogous to its human counterparts, and potentially, would modulate the pathogenicity of anti-P autoantibodies in vivo.

Animals↗
PubMed2005

A prospective study of septicaemia on a paediatric oncology unit: a three-year experience at The Royal Liverpool Children's Hospital, Alder Hey, UK.

Septicaemia in neutropaenic patients is predominantly due to gut translocation [endogenous septicaemia] and contamination of the central venous catheter by microorganisms not carried by the patient [exogenous septicaemia]. To control both types of infection, a protocol was implemented based on pre 1990's parenteral and enteral antimicrobials together with strict hygiene. Surveillance cultures of throat/rectum were taken to distinguish exogenous from endogenous septicaemia and enteral non-absorbable antibiotics are administered as part of selective decontamination of the digestive tract (SDD). This protocol was evaluated in a 14-bedded paediatric oncology unit over a period of 3 years. 313 Septicaemia episodes were recorded in 131 children. 28.4% of the septicaemias were caused by microorganisms associated with the unit, equivalent to 0.82 episodes per 100 patient days. Low-level pathogens such as coagulase-negative staphylococci caused more than 70% of infections. Amongst the potential pathogens, Pseudomonas species (7.8%) and Staphylococcus aureus (5.5%) were predominant. Antibiotic resistance was rare with no superinfections or outbreaks. Four patients (3%) died, two due to Candida species and two due to Pseudomonas aeruginosa. We believe that the addition of enteral non-absorbable antibiotics to systemic antibiotics maintained a low level of resistance and mortality but a randomised controlled trial is indicated to confirm these observations.

Adolescent↗
PubMed2005

Postirradiation morphea and subcutaneous polyarteritis nodosa: case report and literature review.

OBJECTIVE: To describe a case of postirradiation morphea and subcutaneous polyarteritis nodosa occurring simultaneously in a patient and to review the literature on postirradiation autoimmune phenomenon and the potential pathogenesis of such changes. METHODS: A 75-year-old woman with breast cancer treated with chemotherapy and radiation who developed postirradiation morphea and subcutaneous polyarteritis nodosa, both inside and outside of the field of radiation, is described. Literature searches were performed on postirradiation morphea and other radiation-related inflammatory cutaneous conditions and the potential pathogenic mechanisms involved. RESULTS: Twenty-five cases of postirradiation morphea and 8 cases of postirradiation panniculitis were reported in the literature. Only 3 cases of morphea with distant vasculitis occurring in the same patient have been reported and each of these patients had features suggestive of an underlying connective tissue disease. This is the first case of morphea and subcutaneous polyarteritis nodosa occurring in the same location both inside and outside the field of radiation. CONCLUSIONS: Postirradiation morphea is an uncommon condition but is being increasingly recognized. Related phenomena following radiation include postirradiation panniculitis and now postirradiation subcutaneous polyarteritis nodosa. Radiation may be responsible for inducing some of the pathogenic changes seen in scleroderma and other autoimmune diseases. Rheumatologists should be aware of these potential complications of radiation treatment.

Adrenal Cortex Hormones↗
PubMed2003

The Leopoldina international symposium on parasitism, commensalism and symbiosis--common themes, different outcome.

The development of new methods, including genomics, which can even be applied to unculturable microorganisms, has significantly increased our knowledge about bacterial pathogenesis and symbiosis and, in consequence, is profoundly modifying our views on the evolution and the genetic and physiological basis of bacteria-host interactions. The presentations at this symposium revealed conceptual links between bacterial pathogenesis and symbiosis. The close co-operation of experts in both fields will result in significant synergy and new insights into basic mechanisms of bacteria-host interactions and their evolution. The meeting provided fascinating news about the genetic and metabolic consequences that the change in their lifestyle had for bacteria that developed from free-living to permanent host-associated organisms exemplified by intracellular pathogens or symbionts. In addition, surprising similarities but also striking differences between the strategies involved in the establishment of a symbiotic versus a parasitic lifestyle can be noted. In the long run, the characterization of such differences might lead to lifestyle prediction or to an evaluation of the pathogenic potential of newly isolated bacteria via the definition of genetic and/or metabolic signatures characteristic for pathogenic or symbiotic organisms. Moreover, it is expected that these investigations will lead to new strategies for the treatment or prevention of bacterial infections, or the avoidance of pathogen transmission.

Animals↗
PubMed2001

Strong HLA class I--restricted T cell responses in dengue hemorrhagic fever: a double-edged sword?

Dengue is an increasingly important cause of morbidity and mortality in the tropics, but vaccine development has been impeded by a poor understanding of disease pathogenesis and, in particular, of immunologic enhancement. In a large case-control study of Vietnamese patients with dengue hemorrhagic fever (DHF), variation at the HLA-A locus was significantly associated with susceptibility to DHF (P=.02), and specific HLA-A susceptibility and resistance alleles were identified. HLA-A-specific epitopes were predicted from binding motifs, and ELISPOT analyses of patients with DHF revealed high frequencies of circulating CD8 T lymphocytes that recognized both serotype-specific and -cross-reactive dengue virus epitopes. Thus, strong CD8 T cell responses are induced by natural dengue virus infection, and HLA class I genetic variation is a risk factor for DHF. These genetic and immunologic data support both protective and pathogenic roles for dengue virus-specific CD8 T cell responses in severe disease. The potentially pathogenic role of serotype-cross-reactive CD8 T cells poses yet another obstacle to successful dengue vaccine development.

Adolescent↗
PubMed2003

Candida albicans phospholipomannan is sensed through toll-like receptors.

Candida albicans is a common, harmless yeast in the human digestive tract that also causes severe systemic fungal infection in hospitalized patients. Its cell-wall surface displays a unique glycolipid called phospholipomannan (PLM). The ability of PLM to stimulate tumor necrosis factor (TNF)-alpha production by J774 mouse cells correlates with the activation of nuclear factor (NF)-kappaB. We examined the involvement of Toll-like receptors (TLRs) in PLM-dependent stimulation. Compared with wild-type cells, which produced large amounts of TNF-alpha after incubation with PLM, the deletion of the TLR4 and TLR6 genes led to a limited alteration of the PLM-induced response. Deletion of the TLR2 gene completely abolished the cell response. Surface expression of PLM is a phylogenic trait of C. albicans, and the recognition of PLM by TLRs, together with the unique pathogenic potential of C. albicans, suggests that this molecule may be a member of the pathogen-associated molecular pattern family.

Animals↗
PubMed2001

Conserved CXCR4 usage and enhanced replicative capacity of HIV-2/287, an isolate highly pathogenic in Macaca nemestrina.

OBJECTIVE: To investigate viral properties that contribute to the pathogenic potential of HIV-2 in macaques. DESIGN: We compared HIV-2/287, a virus highly pathogenic in Macaca nemestrina, with its non-pathogenic progenitor HIV-2 EHO, for coreceptor usage and ability to infect human and macaque peripheral blood mononuclear cells (PBMC). METHODS: Coreceptor usage was determined in GHOST cells expressing known coreceptors, and in PBMC with coreceptor-specific inhibitors. Infectivity in PBMC was determined by virus titration and p27 antigen production. Early and late products of reverse transcription were measured by PCR with primers specific for the long terminal repeat (LTR), or the gag region, respectively. RESULTS: Both viruses preferentially infect HOS-CD4 cells expressing CXCR4. Inhibition by CXCR4-specific peptide TW70 and monoclonal antibody 12G5 indicated that both viruses use predominantly CXCR4 to infect macaque and human PBMC. HIV-2/287 showed greater infectivity than HIV-2 EHO in macaque cells, but the situation was reversed in human cells. Kinetic analysis of reverse transcription products revealed no restriction in reverse transcription following HIV-2 EHO infection of macaque PBMC. However, comparison of the level of newly initiated HIV-2 EHO DNA in macaque and human PBMC indicated that there is an early restriction, prior to the initiation of reverse transcription. CONCLUSIONS: Results indicate that the adaptation of HIV-2 EHO in M. nemestrina to a highly pathogenic virus HIV-2/287 is not correlated with a shift in or an expansion of coreceptor usage, but with the acquisition of an ability to overcome restrictions for growth in macaque PBMC.

Animals↗
PubMed1995

Endodontic cellulitis 'flare-up'. Case report.

Endodontic cellulitis involves facial swelling which can vary from mild to severe and can occur as a primary case or a flare-up following initial treatment of asymptomatic teeth with periapical lesions. The microbial spectrum in primary cases involves a significant mixture of anaerobic and facultative aerobic microbes, chiefly streptococci. In a previous study, cultures from flare-up cases, utilizing the same anaerobic techniques as in primary cases, revealed an absence of obligate anaerobes and an 80 per cent incidence of facultative aerobic streptococci. These cases also revealed a significant time lapse from onset of symptoms to the cellulitis phase. No sex or age factors were noted in the primary or flare-up cases. The purpose of this case report is to restate a traditional theory, namely, the alteration of the oxidation/reduction potential (Eh), as a major factor for endodontic cellulitis flare-ups; to confirm the pathogenic potential of oral facultative streptococci; and that asymptomatic endodontic lesions tend to exist with mixed aerobic/anaerobic microbial flora.

Adolescent↗
PubMed1999

Primary Shewanella alga septicemia in a patient on hemodialysis.

We report the first Japanese case of primary septicemia with Shewanella alga and also describe the bacteriological characteristics of and results of antibiotic susceptibility tests of the isolate. S. alga was repeatedly isolated, at times simultaneously with Escherichia coli, from the blood of a 64-year-old female undergoing hemodialysis. The isolated organism was determined to be S. alga based on recently published identification criteria, such as hemolysis on sheep blood agar, no acid production from carbohydrates, and growth on agar containing 6. 5% NaCl. Results of antibiotic susceptibility tests demonstrated that the isolate was sensitive to levofloxacin and cefpirome (MICs, </=0.063) but resistant to cefazolin, ceftizoxime, and imipenem (MICs, >128, 64, and 8 microg/ml, respectively). Although the role of S. alga as a human pathogen has not been fully determined, accumulating data suggest that this organism may be a potential pathogen, especially in compromised hosts.

Anti-Bacterial Agents↗