Sensitivity of scopulariopsis brevicaulis to some antimicrobial agents

Sensitivity tests were done against two isolates of Scopulariopsis brevicaulis, using amphotericin B in combination with chloramphenicol, Chloramphenicol alone, amphotericin B in combination with 5-fluorocytosine, and 5-fluorocytosine, myxin and clotrimazole alone. Results indicated that the effectiveness of amphotericin B was improved in the presence of chloramphenicol or 5-fluorocytosine. Growth inhibitory values recorded for chloramphenicol alone and combined with amphotericin B did not show much variation. Resistance of the fungus has been noticed to 5-fluorocytosine; but the organism's response was much better when tested against 5-fluorocytosine in the presence of amphotericin B. Both myxin and clotrimazole proved very effective and their ED50 was 50 and 2.5 ug/ml of the medium, respectively. Thus, clotrimazole may be the drug of choice in the cases of deep scopulariopsis.     

支原体对抗生素的体外敏感性研究

目的研究非淋菌性尿道(宫颈)炎(NGU)患者支原体对12种抗生素敏感性,指导临床治疗。方法男性标本取尿道拭子．女性标本取宫颈拭子,采用支原体培养鉴定及药敏试剂盒进行体外药敏测定。结果126株解脲支原体(Uu)对12种抗生素敏感性从高至低依次为交沙霉素、强力霉素、美满霉素、克拉霉素、四环素、阿奇霉素、罗红霉素、司帕沙星、甲砜霉素、红霉素、可乐必妥和壮观霉素。12株人型支原体(Mh)对12种抗生素敏感性从高至低依次为交沙霉素、强力霉素、美满霉素、司帕沙星、四环素、壮观霉素、可乐必妥、甲砜霉素、红霉素、阿奇霉素、克拉霉素和罗红霉素。结论支原体耐药情况相当普遍。Uu、Mh对相同抗生素具有不同的敏感性。治疗时可依据药敏结果选择用药。     

Sensitivity of ruminal microorganisms to pentachlorophenol

Pentachlorophenol (PCP) is used extensively as a biocidal agent, and there is considerable concern about the adverse effects of this compound in biological ecosystems. The effects of PCP on the growth and fermentative activity of cultures of mixed ruminal microorganisms and the sensitivity of 14 ruminal bacterial species to PCP in pure culture were examined in this study. Increasing concentrations of PCP (9.4 to 375.4 microM) depressed growth and propionate concentrations in cultures of mixed ruminal microorganisms. Wide differences in the sensitivities of ruminal bacterial strains to various concentrations of PCP were observed. Cellulolytic strains were highly sensitive to PCP, while amylolytic, sugar-utilizing, and intermediate acid-utilizing strains were more resistant. Growth of major succinate-producing strains was depressed by PCP. Strains which depend on substrate level phosphorylation appeared to be more resistant. The data suggest that the adverse effects of PCP on ruminal microorganisms may be the result of its role as both an uncoupler of electron transport and a protonophore.     

Pleural reactions to environmental agents.

In the past, pleural disease has been uncommon, generally limited to infection derived from underlying pulmonary involvement or the result of local neoplastic invasion or hematogenous metastases. The deep, protected location of the lung's mesothelial surface provides insufficient defense against environmentally derived very fine biologically active inorganic particles, and a new set of abnormalities--pleural plaques, fibrosis, unique calcification, malignancy (mesothelioma), benign asbestotic effusion--have introduced problems of pathogenesis, diagnosis, management, and therapy. These changes are becoming frequent among individuals who were exposed to asbestos more than 20 years ago. Occupational exposure (direct and indirect), and in some cases environmental exposure (household contacts of asbestos-exposed workers and factory neighborhood residents), have been associated with higher prevalence of radiographically evident pleural abnormalities. What effects such changes will have on morbidity and mortality rates is incompletely understood.     

Susceptibility of Pediococcus spp. to antimicrobial agents

AIM: To investigate the susceptibility of Pediococcus species to antimicrobial agents. METHODS AND RESULTS: The susceptibility to 14 antimicrobial agents of 31 genotypically distinct strains of six Pediococcus species was assessed by using Etests on ISO-sensitest agar supplemented with horse blood. The species included were Pediococcus acidilactici, Pediococcus damnosus, Pediococcus dextrinicus, Pediococcus inopinatus, Pediococcus parvulus and Pediococcus pentosaceus. For several antimicrobial agents, some species were more susceptible than others. The two industrially important species, P. acidilactici and P. pentosaceus, differed with respect to erythromycin and trovafloxacin susceptibility, and in general both species had higher minimum inhibitory concentrations than the other species. In an erythromycin-resistant P. acidilactici, an erythromycin resistance methylase B [erm(B)] gene was identified by PCR. Using a plasmid preparation from strain P. acidilactici 6990, a previously erythromycin-sensitive Lactococcus lactis strain was made resistant. Transformants harboured a single plasmid, sized at 11.6 kb through sequence analysis. In addition, the erm(B) gene was identified within the plasmid sequence. CONCLUSIONS: The phenotypic test indicated the absence of acquired antimicrobial resistance genes in 30 of the strains. SIGNIFICANCE AND IMPACT OF THE STUDY: These results will help in selection of the best Pediococcus strains for use as starter cultures.     

Sensitivity of bacterial coaggregation to chelating agents

Coaggregation between pairs of microorganisms was found to be inhibited by chelating agents, such as acetylacetone, citrate, EDTA and carboxymethylcellulose. Assays were conducted on eight pairs of periodontopathogens and one pair consisting of Escherichia coli and Saccharomyces cerevisiae. The inhibitory effects of the chelating agents were reversible except for Actinomyces naeslundii 12104, the adhesin of which was irreversibly inactivated. Even though the bacteria possessed different kinds of adhesins, their sensitivity to chelating agents appears to be a common property. Non-toxic chelating agents, such as carboxymethylcellulose and citrate, may prove to be useful anti-adhesins.     

Sensitivity of cell-based biosensors to environmental variables

Electrically active living cells cultured on extracellular electrode arrays are utilized to detect biologically active agents. Because cells are highly sensitive to environmental conditions, environmental fluctuations can elicit cellular responses that contribute to the noise in a cell-based biosensor system. Therefore, the characterization and control of environmental factors such as temperature, pH, and osmolarity is critical in such a system. The cell-based biosensor platform described here utilizes the measurement of action potentials from cardiac cells cultured on electrode arrays. A recirculating fluid flow system is presented for use in dose-response experiments that regulates temperature within +/-0.2 degrees C, pH to within +/-0.05 units, and allows no significant change in osmolarity. Using this system, the relationship between the sensor output parameters and environmental variation was quantified. Under typical experimental conditions, beat rate varied approximately 10% per degree change in temperature or per 0.1 unit change in pH. Similar relationships were measured for action potential amplitude, duration, and conduction velocity. For the specific flow system used in this work, the measured environmental sensitivity resulted in an overall beat rate variation of +/-4.7% and an overall amplitude variation of +/-3.3%. The magnitude of the noise due to environmental sensitivity has a large impact on the detection capability of the cell-based system. The significant responses to temperature, pH, and osmolarity have important implications for the use of living cells in detection systems and should be considered in the design and evaluation of such systems.     

Susceptibility of the Lyme disease spirochete to seven antimicrobial agents.

The antimicrobial susceptibility of five Lyme disease spirochete strains (two human and three tick isolates) was determined. A macrodilution broth technique was used to determine on three separate test occasions the minimal inhibitory concentrations (MICs) of seven antibiotics. The Lyme disease spirochete was most susceptible to erythromycin with a MIC of less than or equal to 0.06 micrograms/ml. The spirochete was also found to be susceptible to minocycline, ampicillin, doxycycline, and tetracycline-HCL with respective mean MICs of less than or equal to 0.13, less than or equal to 0.25, less than or equal to 0.63, and less than or equal to 0.79 micrograms/ml. The spirochete was moderately susceptible to penicillin G with a mean MIC of 0.93 micrograms/ml. All strains were resistant to rifampin at the highest concentration tested (16.0 micrograms/ml).     

Survival of microorganisms on antimicrobial filters and the removal efficiency of bioaerosols in an environmental chamber

Exposure to bioaerosols causes various adverse health effects including infectious and respiratory diseases, and hypersensitivity. Controlling exposure to bioaerosols is important for disease control and prevention. In this study, we evaluated the efficacies of various functional filters coated with antimicrobial chemicals in deactivating representative microorganisms on filters or as bioaerosols. Tested functional filters were coated with different chemicals that included (i) Ginkgo and sumac, (ii) Ag-apatite and guanidine phosphate, (iii) SiO2, ZnO, and Al2O3, and (iv) zeolite. To evaluate the filters, we used a model ventilation system (1) to evaluate the removal efficiency of bacteria (Escherichia coli and Legionella pneumophila), bacterial spores (Bacillus subtilis spore), and viruses (MS2 bacteriophage) on various functional filters, and (2) to characterize the removal efficiency of these bioaerosols. All experiments were performed at a constant temperature of 25 degrees C and humidity of 50%. Most bacteria (excluding B. subtilis) rapidly decreased on the functional filter. Therefore, we confirmed that functional filters have antimicrobial effects. Additionally, we evaluated the removal efficiency of various bioaerosols by these filters. We used a six-jet collision nebulizer to generate microbial aerosols and introduced it into the environmental chamber. We then measured the removal efficiency of functional filters with and without a medium-efficiency filter. Most bioaerosol concentrations did not significantly decrease by the functional filter only but decreased by a combination of functional and medium-efficiency filter. In conclusion, functional filters could facilitate biological removal of various bioaerosols, but physical removal of these by functional was minimal. Proper use of chemical-coated filter materials could reduce exposure to these agents.     

Chemosensitization of fungal pathogens to antimicrobial agents using benzo analogs.

Activities of conventional antifungal agents, fludioxonil, strobilurin and antimycin A, which target the oxidative and osmotic stress response systems, were elevated by coapplication of certain benzo analogs (aldehydes and acids). Fungal tolerance to 2,3-dihydroxybenzaldehyde or 2,3-dihydroxybenzoic acid was found to rely upon mitochondrial superoxide dismutase (SOD2) or glutathione reductase (GLR1), genes regulated by the HOG1 signaling pathway, respectively. Thus, certain benzo analogs can be effective at targeting cellular oxidative stress response systems. The ability of these compounds to chemosensitize fungi for improved control with conventional antifungal agents is discussed.