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At least 235 records · Page 13Linked to original sources
PubMed2003

Gingivitis and toothbrushes: potential roles in viridans streptococcal bacteraemia.

We report a case of Streptococcus oralis bacteraemia in a paediatric neutropenic patient with acute myeloid leukaemia whose predominant form of oral compromise was severe gingivitis, rather than mucositis. By phenotypic and genotypic analyses, the strain of S. oralis from blood culture was indistinguishable from an isolate from his mouth, suggesting that gingivitis may have provided a portal of entry for viridans streptococci into the bloodstream. To improve the patient's oral and dental hygiene and reduce gingivitis, conventional disposable foam toothettes were substituted with a new soft toothbrush for use as part of the oral care protocol. As there are no guidelines regarding the frequency of replacement of toothbrushes used by immunocompromised patients, the brush was swabbed regularly and culture performed to detect microbial colonization. Viridans streptococci were cultured from the toothbrush after 2 weeks of use. Phenotypic, followed by genotypic analyses, demonstrated that a strain of S. oralis from the toothbrush was indistinguishable from the strain previously isolated from blood culture and mouth. Soft toothbrushes may be useful tools for maintaining oral hygiene in immunocompromised individuals. However the results of this study indicate that regular replacement is warranted, as the toothbrush itself may become colonized with the organisms responsible for bacteraemia.

Anti-Bacterial Agents↗
PubMed1976

Mutagenicity of aflatoxins related to their metabolism and carcinogenic potential.

Aflatoxins and their animal biotransformation products were screened for carcinogenic potential using the Ames' in vitro microbial detection system for carcinogens as bacterial mutagens [B. N. Ames et al. (1973) Proc. Natl. Acad. Sci. USA 70,2281-2285]. Aflatoxicol, aflatoxins G1 and M1, aflatoxicol H1, and aflatoxins Q1, B2, P1, G2, B2a, and G2a, listed in order of decreasing mutagenic potency, were all less active than aflatoxin B1. No compound possesses activity in the absence of the rat liver preparation, and this indicates none of the animal metabolites are the ultimate mutagenic and/or carcinogenic species. The relative mutagenic potency observed with this in vitro system qualitatively correlates with in vivo carcinogenic data. Comparison of both methods indicates: (i) aflatoxin B1 possessed the structure optimal for both mutagenicity and carcinogenicity, (ii) the decreased carcinogenicity of various animal metabolites is associated with their decreased mutagenicity, and (iii) the 2,3-double bond is involved in both the mutagenic and carcinogenic activity of aflatoxins. The Ames' assay has been demonstrated to be an extremely promising (toxicological) tool for the analysis of mycotoxins for mutagenic and/or carcinogenic activity.

Aflatoxins↗
PubMed2004

Etiologies and manifestations of persistent diarrhea in adults with HIV-1 infection: a case-control study in Lima, Peru.

UNLABELLED: OBJECTIVE We sought to determine the etiologies, manifestations, and risk factors for persistent (> or =7 days) diarrhea in human immunodeficiency virus type 1 (HIV-1)-infected persons in Peru. DESIGN: The present study is a case-control study of 147 HIV-1-infected case subjects with persistent diarrhea and 147 HIV-1-infected control subjects without diarrhea. METHODS: We obtained clinical, demographic, and exposure data, CD4 lymphocyte counts, and stool samples for detection of enteric parasitic and bacterial pathogens and rotavirus. RESULTS: One or more enteric pathogen was identified in 55% of case subjects and 21% of control subjects (odds ratio adjusted for CD4 lymphocyte count, 3.8; 95% confidence interval, 2.2-6.5). The median CD4 lymphocyte count was highest with pathogen-free diarrhea and lowest with Cryptosporidium infection. Cryptosporidium species (the most frequent pathogen), Giardia lamblia, Aeromonas species, Campylobacter species, and rotavirus were all significantly associated with diarrhea. Bacterial pathogens were significantly associated with G. lamblia and rotavirus infection. Of the bacterial pathogens (Aeromonas, Campylobacter, Salmonella, and Vibrio species and enterotoxigenic Escherichia coli), only 24% were susceptible to cotrimoxazole, whereas 90% were susceptible to ciprofloxacin. In no case did the sensitivity or positive predictive value of specific clinical and laboratory findings for curable enteric infections exceed 50%. CONCLUSIONS: Several enteric pathogens were associated with diarrhea in HIV-1-infected case subjects in Peru, especially among those who were heterosexual. Clinical findings were poor predictors of detectable microbial etiology. The guidelines for initial management of chronic diarrhea with sulfamethoxazole-trimethoprim in HIV-1-infected persons require revision, at least in settings where prophylaxis with this agent is common.

Adult↗
PubMed2003

Tírez lake as a terrestrial analog of Europa.

Tírez Lake (La Mancha, central Spain) is proposed as a terrestrial analogue of Europa's ocean. The proposal is based on the comparison of the hydrogeochemistry of Tírez Lake with the geochemical features of the alteration mineralogy of meteoritic precursors and with Galileo's Near Infrared Mapping Spectrometer data on Europa's surface. To validate the astrobiological potential of Tírez Lake as an analog of Europa, different hydrogeochemical, mineral, and microbial analyses were performed. Experimental and theoretical modeling helped to understand the crystallization pathways that may occur in Europa's crust. Calculations about the oxidation state of the hypothetical Europan ocean were estimated to support the sulfate-rich neutral liquid model as the origin of Europa's observed hydrated minerals and to facilitate their comparison with Tírez's hydrogeochemistry. Hydrogeochemical and mineralogical analyses showed that Tírez waters corresponded to Mg-Na-SO(4)-Cl brines with epsomite, hexahydrite, and halite as end members. A preliminary microbial ecology characterization identified two different microbial domains: a photosynthetically sustained community represented by planktonic/benthonic forms and microbial mat communities, and a subsurficial anaerobic realm in which chemolithotrophy predominates. Fluorescence in situ hybridization has been used to characterize the prokaryotic diversity of the system. The subsurficial community seemed to be dominated by sulfate-reducing bacteria and methanogens. Frozen Tírez brines were analyzed by Fourier-transform infrared techniques providing spectra similar to those reported previously using pure components and to the Galileo spectral data. Calorimetric measurements of Tírez brines showed pathways and phase metastability for magnesium sulfate and sodium chloride crystallization that may aid in understanding the processes involved in the formation of Europa's icy crust. The use of fluorescence hybridization techniques for microbial detection and characterization in hypersaline environments makes this methodology strongly advisable for future Europa astrobiological missions.

Chemical Phenomena↗
PubMed1998

Lack of efficacy for conventional gamma irradiation of platelet concentrates to abrogate bacterial growth.

The maximum storage time for platelet concentrates is 5 days, owing to the higher risk bacterial contamination with longer storage. The expiration date could potentially be extended if a rapid system to detect microbial contamination or a safe sterilization technique could be developed and easily implemented. Gamma irradiation has decreased bacterial contamination in food products. Conventional doses of gamma irradiation were tested for their efficacy in decreasing bacterial growth during the 5-day platelet shelf life. An initial pilot study determined that bacteria suspended in normal saline at concentrations of 1 to 2 x 10(7) colony-forming units per milliliter showed a dose-related susceptibility to gamma irradiation. Subsequently, four platelet concentrates were pooled, inoculated with a known concentration of Staphylococcus autreus or Serratia marcescens, and divided. The concentrates were exposed to varying amounts of gamma irradiation, ie, no irradiation (control), 25, 50, and 75 Gy, and subjected to typical blood bank storage conditions. The platelet concentrates were sampled daily for 7 consecutive days to monitor bacterial growth by quantitative cultures. An inverse linear dose-related extinction of bacteria was evident in the pilot study with an extrapolated total kill in the 100 to 150 Gy range. There is no difference in bacterial growth with S aureus using irradiation levels from 0 to 75 Gy. A 1-day delay in bacterial growth at 75 Gy was found with S marcescens compared with units irradiated with 0 through 50 Gy. Exposure of bacteria-contaminated platelet concentrates on storage day zero to gamma irradiation at levels up to 75 Gy is ineffective at sterilizing the platelet concentrates. Higher levels of irradiation may be effective in sterilizing platelet concentrates. Function, survival, and sterility after higher than conventional levels of irradiation need further study.

Bacteria↗
PubMed1995

An outbreak of pyrogenic reactions in chronic hemodialysis patients associated with hemodialyzer reuse.

In February 1992, 22 patients undergoing chronic hemodialysis at an outpatient dialysis center experienced pyrogenic reactions (PR). The PR rate was significantly greater (p < 0.001) during the epidemic (February 3-5) than the pre-epidemic period (November 1, 1992-February 1, 1992). All patients with PR used dialyzers that had been manually reprocessed either on February 1 or 3. These dialyzers contained up to 120.8 EU/ml of endotoxin in the blood compartment. The only dialyzer reprocessed before February 1 that was available for analysis was found to contain no detectable endotoxin, while dialyzers reprocessed during the epidemic period contained a median endotoxin concentration of 52.8 EU/ml. The bioburden of water used to prepare dialysate was in excess of the Association for the Advancement of Medical Instrumentation (AAMI) standard for water, < or = 200 colony forming units (CFU)/ml. Samples of treated water collected in the reuse area were within AAMI standards at the time of the investigation (February 11 and February 26), but before the investigation, water samples were assayed with a culture method that could not detect microbial concentrations below 10(3) CFU/ml. In addition, the treated water feed line to the disinfectant container may never have been disinfected. However, no samples were collected from this line during the investigation. This outbreak emphasizes the need to use water that meets the AAMI bacteriologic and endotoxin standards of < or = to 200 CFU/ml and/or 5 EU/ml, respectively, for reprocessing hemodialyzers nad to ensure that appropriate culture techniques are used for treated water dialysate.

Adult↗
PubMed1973

Microflora of soil as viewed by freeze-etching.

The indigenous microflora of soil were released from the soil materials and concentrated without the occurrence of growth by use of a blending-simple centrifugation procedure. The cell concentrate was then frozen-etched and viewed by transmission electron microscopy. Criteria were established for detecting microbial cells among the residual soil debris. The freeze-etching of the soil cell concentrate provided results on cell size distributions in agreement with those obtained by thin sectioning. However, the blending-simple centrifugation procedure for cell release and concentration from soil allowed the observation of large cells (>/=1.0 mum in diameter) which apparently are missed by the "exhaustive centrifugal washing" cell separation-concentration procedure. The procedure of blending-simple centrifugation combined with the viewing of frozenetched preparations allowed evaluations of the soil microflora for cellular diameters, length-width ratios, shapes, and structure.

Bacteria↗
PubMed2025

Biofilms in clinical infection: pathophysiology, diagnosis, and the evolving therapeutic landscape.

Biofilms are structured communities of microorganisms encased in a self-produced polymeric matrix that typically adhere to surfaces. Recent research, however, has revealed that non-attached aggregates share many common traits with the surface-dependent biofilms. This mode of bacterial growth provides enhanced protection against antibiotics and resistance to host immune defenses. Biofilms require higher antibiotic concentrations than those needed to inhibit planktonic bacteria, necessitating prolonged high-dose and combination therapies to achieve effective eradication. This increased resistance is attributed to multiple factors, including the protective extracellular matrix, reduced metabolic activity of bacteria within the biofilm, and also the ability of bacterial genomes to rapidly adjust in response to environmental changes. Diagnostic modalities such as sonication, tissue culture, and polymerase chain reaction-based assays currently dominate clinical diagnostics of biofilm infections due to their practicality, cost-effectiveness, and proven reliability. Recent research has led to innovative treatment strategies that target biofilm structure, enhance drug delivery, and modulate host-pathogen interactions. This review summarizes our current knowledge of biofilm formation, explores the current techniques for detecting microbial biofilms, and discusses future perspectives for advancing diagnostic and therapeutic strategies.

Biofilms↗
PubMed2006

Controlled clinical comparison of VersaTREK and BacT/ALERT blood culture systems.

To assess the relative yields in automated microbial detection systems of bacteria and yeasts isolated from the blood of adult patients with suspected sepsis, we compared the new VersaTREK system (VTI) (TREK Diagnostic Systems, Cleveland, OH) to the BacT/ALERT 3D system (3D) (bioMérieux, Inc., Durham, NC). Identical protocols were followed for the two systems. Paired aerobic (REDOX 1) and anaerobic (REDOX 2) VTI media were compared with standard aerobic (SA) and anaerobic (SN) 3D media; each of the four culture bottles was filled with 6 to 9 ml of blood. All bottles flagged positive by the instruments were subcultured to determine both true-positive (growth) and false-positive (no growth) cultures. Additionally, to assess false-negative bottles, terminal subcultures were done on all negative companion bottles to true-positive bottles. All isolates were identified by standard methods. All 4 bottles were adequately filled and yielded 413 clinically significant isolates in 5,389 (79%) of the 6,786 4-bottle sets obtained. Although no overall difference in yield or in time to detection was detected between the two systems, significantly more streptococci and enterococci as a group were detected by VTI. Moreover, significantly more microorganisms were detected by VTI for patients receiving antimicrobial therapy. The two systems were comparable (P, not significant) at detecting the 179 unimicrobial episodes of bacteremia seen. False-positive rates for aerobic and anaerobic bottles, respectively, were 1.6% and 0.9% for VTI and 0.7% and 0.8% for 3D. We conclude that the VTI and 3D systems are comparable for detection of bloodstream infections with bacteria or yeasts.

Adult↗
PubMed1995

The diagnostic value of amniotic fluid Gram stain examination and limulus amebocyte lysate assay in patients with preterm birth.

The purpose of this study was to determine the value of Gram stain examination and Limulus amebocyte lysate (LAL) test in the detection of intraamniotic infection. Ninety women with preterm labor and intact membranes (n = 55) or preterm premature rupture of membranes (PROM) (n = 35) who delivered prematurely were included in the study. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for mycoplasmas. Amniotic fluid analysis included Gram stain examination and limulus amebocyte lysate tests. The prevalence of positive amniotic culture was 32.2% (29/90) and the most common isolate was Ureaplasma urealyticum. Patients with preterm PROM group had a higher rate of infection than those with preterm labor and intact membranes 57.1% (20/35) vs. 16.4% (9/55), respectively (p = 0.0001). We found a lower gestational age at delivery and lower mean birth weight in neonates born to mothers with a positive amniotic fluid culture than those with negative amniotic fluid culture. The combined use of Gram stain examination and LAL test had a sensitivity and specificity of 51.7% (15/29) and 95.1% (58/61) respectively for the detection of positive amniotic fluid culture. We conclude that Gram stain examination and LAL test are rapid, simple and specific tests that can be used to detect microbial invasion of the amniotic cavity except in patients with mycoplasmas infections.

Adult↗
PubMed2004

CpG DNA induces IgG class switch DNA recombination by activating human B cells through an innate pathway that requires TLR9 and cooperates with IL-10.

TLRs are pattern recognition receptors that initiate innate immune responses. TLR9 detects microbial DNA with hypomethylated CpG motifs and in humans is preferentially expressed by IFN-alpha-producing plasmacytoid dendritic cells and B cells. In addition to favoring IFN-alpha release, TLR9 signals B cell activation, proliferation, and IgM production. Recent findings suggest that CpG DNA-TLR9 interaction plays a key role in systemic lupus erythematosus and rheumatoid arthritis, two autoimmune disorders characterized by dysregulated production of DNA-reactive IgG. We show that CpG DNA initiates germline C(gamma)1, C(gamma)2, and C(gamma)3 gene transcription by activating B cells through a TLR9-mediated NF-kappaB-Rel-dependent innate pathway that cooperates with IL-10 through STAT proteins and IFN-responsive factors. This pathway is inhibited by chloroquine, a drug that attenuates the clinical manifestations of IgG-mediated autoimmune disorders. Germline C(gamma) gene transcription is associated with up-regulation of activation-induced cytidine deaminase, a key element of the B cell class switch-inducing machinery, and is followed by class switch DNA recombination from C(micro) to C(gamma)1, C(gamma)2, and C(gamma)3. Subsequent IgG production requires additional signals from BCR and a B cell-activating factor of the TNF family (BAFF), produced by dendritic cells upon exposure to IFN-alpha. Our findings suggest that CpG DNA-TLR9 interaction may be important to initiate or amplify early T cell-independent IgG responses against pathogens. This implies that CpG DNA released during infections may exacerbate autoimmunity by stimulating autoreactive B cells to switch from an IgM to a more pathogenic IgG isotype.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Recent advances in the diagnosis and management of infection in the organ transplant recipient.

Infection remains a significant cause of morbidity and mortality in organ transplant patients, with significant infection being found in more than half of these individuals posttransplant. The most important principles of patient treatment are prevention, early diagnosis, and specific therapy. The nature of the antimicrobial therapy required both for infection prevention and treatment is closely linked to the immunosuppressive therapy being administered. A particular challenge in the transplant patient is that the antiinflammatory effects of antirejection therapy tend to obscure the manifestations of infection until relatively late in the disease process, thus putting particular emphasis on more aggressive diagnostic approaches-imaging procedures, biopsy, and new techniques for microbial detection (antigen and DNA detection). Antimicrobial therapy can be administered in three ways: therapeutically, prophylactically, and preemptively. Particularly given the propensity for adverse interactions between antimicrobial agents and cyclosporine and tacrolimus, there is a particular emphasis on prophylactic and preemptive use of antimicrobials.

Anti-Infective Agents↗
PubMed2002

[The infections by Chlamydia trachomatis and Neisseria gonorrhoeae].

Among sexually transmitted diseases, Chlamydia trachomatis and Neisseria gonorrhoeae infections are found most frequently. Recently, their incidence in youths has increased. The rate of infection by human immunodeficiency virus is increased in patients who have been infected by Chlamydia trachomatis. In view of this, early detection and treatment of Chlamydia trachomatis infection appear to be important. Asymptomatic infections by Chlamydia trachomatis and Neisseria gonorrhoeae are not rare among gynecological patients. However, in patients infected by both of these pathogens it is difficult to detect microbial antigens using specific antibodies. Therefore, patients suspected of infection by these pathogens should receive precise genetic testing for Chlamydia trachomatis and Neisseria gonorrhoeae, and the results of such tests should be evaluated carefully.

Chlamydia Infections↗
PubMed1992

Automation in clinical microbiology.

Automation was introduced into the clinical microbiology laboratory in the 1960s but initially met with limited success. Today, instruments are an integral part of many clinical laboratories and are used for microbial detection, identification, and susceptibility testing; detection of positive blood cultures; screening urine samples for potential pathogens; and assaying levels of antimicrobial agents in body fluids. Automation has allowed more rapid diagnosis and elimination of the subjective interpretation of many manual tests. In addition, in some cases, automated tests are more sensitive and specific than manual techniques. However, automated testing often is more expensive than manual testing and is associated with the possibility of mechanical failure. Automation will continue to be an important part of the clinical microbiology laboratory and in the future will include more molecular biology technologies, such as the polymerase chain reaction. Perhaps practical applications of flow cytometry will be identified.

Automation↗
PubMed2004

Polymerase chain reaction identification of microorganisms in previously root-filled teeth in a South Korean population.

A large body of evidence indicates that microorganisms are the primary causative agents of endodontic treatment failures. This study intended to assess the occurrence of nine putative endodontic pathogens in root-filled teeth associated with periradicular lesions in a South Korean population using a culture-independent molecular approach. Fourteen root-filled teeth with persistent periradicular diseases were selected for retreatment. After removal of the root canal filling, the canals were sampled, and a polymerase chain reaction assay using taxon-specific oligonucleotide primers was used for microbial detection. Bacteria were present in all cases, as revealed by amplification using ubiquitous 16S rDNA primers. The most frequently detected taxon was Enterococcus faecalis (64%), followed by Streptococcus spp. (21%) and Tannerella forsythensis (14%). The results of this study using a highly sensitive identification method are concurrent with those from other geographical locations using diverse identification methods in that E. faecalis is the main species found in cases of root-filled teeth associated with periradicular lesions.

Adolescent↗
PubMed2005

Perspectives on emerging zoonotic disease research and capacity building in Canada.

Zoonoses are fundamental determinants of community health. Preventing, identifying and managing these infections must be a central public health focus. Most current zoonoses research focuses on the interface of the pathogen and the clinically ill person, emphasizing microbial detection, mechanisms of pathogenicity and clinical intervention strategies, rather than examining the causes of emergence, persistence and spread of new zoonoses. There are gaps in the understanding of the animal determinants of emergence and the capacity to train highly qualified individuals; these are major obstacles to preventing new disease threats. The ability to predict the emergence of zoonoses and their resulting public health and societal impacts are hindered when insufficient effort is devoted to understanding zoonotic disease epidemiology, and when zoonoses are not examined in a manner that yields fundamental insight into their origin and spread. Emerging infectious disease research should rest on four pillars: enhanced communications across disciplinary and agency boundaries; the assessment and development of surveillance and disease detection tools; the examination of linkages between animal health determinants of human health outcomes; and finally, cross-disciplinary training and research. A national strategy to predict, prevent and manage emerging diseases must have a prominent and explicit role for veterinary and biological researchers. An integrated health approach would provide decision makers with a firmer foundation from which to build evidence-based disease prevention and control plans that involve complex human/animal/environmental systems, and would serve as the foundation to train and support the new cadre of individuals ultimately needed to maintain and apply research capacity in this area.

Animals↗
PubMed2004

Detection of biosphere frontier by using phosphatase activity.

A wide variety of methods have been proposed to detect microbial activities, but most of them can be applied to limited categories of terrestrial organisms. We propose here to use phosphatase activity, which seems to be an essential catalytic activity for all the terrestrial organisms, and possibly for extraterrestrial organisms. We determined phosphatase activity in core samples, chimney samples, and sea water samples obtained in submarine hydrothermal systems located at Suiyo Seamount, Izu-Bonin Arc, and South Mariana. It was shown that phosphatase activity is one of possible biomarkers for extant life.

Acid Phosphatase↗