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1.
Mycobacterium avium complex strains previously not exposed to any antituberculosis agents could be divided into two groups according to their susceptibility to rifampicin and ansamycin; one group susceptible to 80 micrograms/ml rifampicin and to 1.25 micrograms/ml ansamycin, and another resistant to these concentrations. In each group, the ratio of the minimal inhibitory concentration of ansamycin against that of rifampicin was greatly different depending on the strain. This naturally occurring resistance to rifampicin and ansamycin was frequently correlated to naturally occurring resistance to ethambutol, kanamycin, enviomycin, kitasamycin, and minocycline, but not correlated to that to isoniazid and sulfadimethoxine. Ansamycin was more active than rifampicin against M. bovis, M. kansasii, M. marinum, M. xenopi, and M. haemophilum.  相似文献   

2.
A medium for the selective isolation and enumeration of Mycobacterium avium-intracellulare and M. scrofulaceum (MAIS) was developed, based upon the ability of these mycobacteria to utilize Tween 80 as sole carbon source and grow optimally at pH 5.5 on a simple mineral salts medium. Representative MAIS strains had higher efficiencies of plating on the Tween 80 medium compared with Middlebrook 7H10. It was shown that nonmycobacterial organisms in natural waters had lower efficiencies of plating on the Tween 80 medium and smaller colonies, thus allowing direct isolation and enumeration of the slowly growing mycobacteria without overgrowth.  相似文献   

3.
Concentrations of essential oils showing high volatility decreased substantially in broth and agar media when incubated under open conditions. The decrease in the half life was from 0.7 to 38 hr in broth medium at 27 C. When evaporation was prevented by sealing, MIC values against Aspergillus fumigatus, Candida albicans and Trichophyton mentagrophytes by broth or agar dilution assay were lowered two to eight-fold, as compared with those obtained under open conditions. Addition of Tween 80 caused a rise of the MICs against A. fumigatus by two to four-fold in broth dilution assay, but little affected the MICs in agar dilution assay.  相似文献   

4.
利用含有Tween 80的琼脂平板和摇瓶发酵法,从若尔盖高原土壤中筛选产脂肪酶菌株.通过菌落形态和菌体特征观察初步对菌种进行鉴定,得到一株产低温脂肪酶的适冷菌Pseudomonassp.DL-B,并设计正交试验对该菌株的产酶发酵培养条件进行了优化.摇瓶实验表明,该菌株最适产酶发酵培养基为:蔗糖10 g/L,蛋白胨20 ...  相似文献   

5.
In Vitro Effect of Rifampin on Mycobacteria   总被引:5,自引:2,他引:3       下载免费PDF全文
Rifampin inhibited 20 strains of Mycobacterium tuberculosis in concentrations of 0.005 to 0.02 mug/ml in 7H-9 broth with Tween 80 and killed all or nearly all of the inoculum in four to eight times greater concentrations. In the same medium without Tween 80, as well as on 7H-10 agar, about 16 to 64 times these amounts were required to produce the same effect. Rifampin was also active against M. kansasii and some of the nonchromogenic mycobacteria. The incidence of mycobacterial cells resistant to rifampin within the cultures studied was in the range of one to four per 10(8) to 10(9) colony-forming units with concentrations of 4 to 125 mug of rifampin per ml. Only one of the Battey cultures and that of M. fortuitum yielded cells resistant to rifampin at 125 mug/ml but not at 500 mug/ml. The same strains yielded more than double that number of organisms resistant to streptomycin and up to 100 times more organisms resistant to isoniazid. All three drugs stopped the growth or reduced the mycobacterial population in growing cultures after contact for 24 to 48 hr. Complete inhibition of growth was produced by rifampin at 1.0 mug/ml in an average of 6 days and by streptomycin at 5.0 mug/ml in 3 days. After an average contact of 10.7 days with rifampin, five of seven strains resumed growth and all strains began regrowth after exposure to streptomycin for 9.4 days. The marked susceptibility of M. tuberculosis and of atypical mycobacteria to rifampin in vitro and the relatively low incidence of resistant mutants suggests that this agent may have clinical usefulness in the treatment of tuberculosis and some other mycobacterioses.  相似文献   

6.
Comparison of Mycobacterial Cultures on Agar and Lowenstein Medium   总被引:2,自引:1,他引:1       下载免费PDF全文
In a comparison of Lowenstein's medium with two agar media, 7H10 without and with the addition of Triton WR 1339, 4,100 sputa were planted on all three, yielding 803 (19.6%) positive cultures. The addition of Triton WR 1339 to the 7H10 medium made it possible to observe the cord formation directly on the isolation plates and did not alter, in any respect, the results obtained with the basic 7H10 medium. The agar media produced much earlier and more positive cultures than Lowenstein's medium. A greater number of cultures showed drug resistance on Lowenstein's medium as compared with the agar media.  相似文献   

7.
The growth rate of Mycobacterium avium subsp. paratuberculosis was assessed by different methods in 7H9 medium supplemented with OADC (oleic acid, albumin, dextrose, catalase), Tween 80, and mycobactin J. Generation times and maximum specific growth rates were determined by wet weight, turbidometric measurement, viable count, and quantitative PCR (ParaTB-Kuanti; F57 gene) for 8 M. avium subsp. paratuberculosis strains (K10, 2E, 316F, 81, 445, 764, 22G, and OVICAP 49). Strain-to-strain differences were observed in growth curves and calculated parameters. The quantification methods gave different results for each strain at specific time points. Generation times ranged from an average of 1.4 days for viable count and qPCR to approximately 10 days for wet weight and turbidometry. The wet-weight, turbidometry, and ParaTB-Kuanti qPCR methods correlated best with each other. Generally, viability has been assessed by viable count as a reference method; however, due to M. avium subsp. paratuberculosis clumping problems and the presence of noncultivable M. avium subsp. paratuberculosis cells, we conclude that qPCR of a single-copy gene may be used reliably for rapid estimation of M. avium subsp. paratuberculosis bacterial numbers in a sample.  相似文献   

8.
Development of novel Alicyclobacillus spp. isolation medium   总被引:1,自引:0,他引:1  
AIM: To develop a new isolation medium with higher recovery rates of Alicyclobacillus spp. METHODS AND RESULTS: SK agar was developed with optimized incubation temperature, pH, acidulant, Tween 80 concentration and divalent cation addition. Results indicate that detection of Alicyclobacillus spp. by SK agar was significantly higher (P > 0.05) than those obtained by K agar, orange serum agar, and potato dextrose agar. CONCLUSIONS: Current media used for Alicyclobacillus spp. isolation still resulted in high numbers of false negative products. The sensitivity of SK agar to Alicyclobacillus spp. allows detection of low numbers of Alicyclobacillus spp. and also provides a more higher isolation results compared with currently used media. SIGNIFICANCE AND IMPACT OF THE STUDY: SK agar will be useful to the fruit juice industry to obtain more accurate numbers of contaminant Alicyclobacillus spp. With this media, false negative samples can be reduced, and the likelihood of exported products being rejected can be greatly reduced.  相似文献   

9.
Reference strains and clinical isolates of Peptococcus and Peptostreptococcus spp. were evaluated for their growth response in supplemented thioglycolate-yeast extract media. Supplements used included various combinations of hemin, menadione, sodium bicarbonate, and Tween 80. Parallel studies were done to compare the efficiency of recovery of viable cells grown in thioglycolate-based media and Wilkins-Chalgren broth and agar. In addition, the effects of age of the medium and medium storage on viable cell yields for reference strains were determined. Reference strains grown in freshly prepared thioglycolate-yeast extract medium supplemented with sodium bicarbonate produced a 10-fold greater increase in the number of viable cells recovered after 24 h of incubation than did the same organisms cultivated in Wilkins-Chalgren medium. The efficiency of recovery of organisms when either mid-logarithmic- or mid-stationary-phase cells were used to prepare standardized inocula was similar. The results suggest that thioglycolate-yeast extract medium supplemented with sodium bicarbonate is more productive than Wilkins-Chalgren medium for the cultivation of anaerobic gram-positive cocci and may represent a suitable alternative for antimicrobial susceptibility testing of these organisms.  相似文献   

10.
Selective and differential media were designed for each species of Pityrosporum; P. pachydermatis, P. ovale, and P. orbiculare in order to make feasible a quantitative cultivation. Medium for P. pachydermatis (medium A) was composed of 1% trypticase peptone (BBL), 0.5% yeast extract (BBL), 0.3% glucose, 0.2% NaCl, 1.2% KH2 PO4 (anhydrous), 1.5% agar, 0.01% ampicillin, and 0.025% cycloheximide with a pH of 5.5. Medium for P. ovale (medium B) was medium A supplemented with 0.05% sodium acetate (anhydrous), 0.2% Tween 80, and 0.025% (selective medium) or 0.075% (differential medium) sodium laurate. Medium for P. orbiculare was medium B (devoid of laurate) supplemented with 2% olive oil, 0.25% glycerol, 0.25% gall powder, 0.05% sodium palmitate, 0.05% sodium stearate, 0.05% sodium oleate and 8% (selective medium) or 10% (differential medium) sodium lactate and an increase in Tween to 1%. For isolation of Pityrosporum, specimens were suspended in 0.1% Tween 80 solution and inoculated onto agar plates of three selective media. The plates were incubated aerobically at 37 C for 8–10 days under conditions of prevention of water loss from the media. The plating efficiency of each selective medium, expressed as a ratio of cultural counts to microscopic counts was generally over 70%. Species of Pityrosporum could also be identified when we inoculated the cell suspension onto differential agar plates and incubated the preparations at 37 C for 7 days.  相似文献   

11.
Reference strains and clinical isolates of Peptococcus and Peptostreptococcus spp. were evaluated for their growth response in supplemented thioglycolate-yeast extract media. Supplements used included various combinations of hemin, menadione, sodium bicarbonate, and Tween 80. Parallel studies were done to compare the efficiency of recovery of viable cells grown in thioglycolate-based media and Wilkins-Chalgren broth and agar. In addition, the effects of age of the medium and medium storage on viable cell yields for reference strains were determined. Reference strains grown in freshly prepared thioglycolate-yeast extract medium supplemented with sodium bicarbonate produced a 10-fold greater increase in the number of viable cells recovered after 24 h of incubation than did the same organisms cultivated in Wilkins-Chalgren medium. The efficiency of recovery of organisms when either mid-logarithmic- or mid-stationary-phase cells were used to prepare standardized inocula was similar. The results suggest that thioglycolate-yeast extract medium supplemented with sodium bicarbonate is more productive than Wilkins-Chalgren medium for the cultivation of anaerobic gram-positive cocci and may represent a suitable alternative for antimicrobial susceptibility testing of these organisms.  相似文献   

12.
Acid resistance of Mycobacterium paratuberculosis was examined as a function of growth conditions (i.e., in vitro growth medium and pH). M. paratuberculosis was cultured in either fatty acid-containing medium (7H9-OADC) or glycerol-containing medium (WR-GD or 7H9-GD) at two culture pHs (pHs 6.0 and 6.8). Organisms produced in these six medium and pH conditions were then tested for resistance to acetate buffer at pHs 3, 4, 5, and 6 at 20 degrees C. A radiometric culture method (BACTEC) was used to quantify viable M. paratuberculosis cell data at various acid exposure times, and D values (decimal reduction times, or the times required to kill a 1-log(10) concentration of bacteria) were determined. Soluble proteins of M. paratuberculosis grown under all six conditions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to identify proteins that may be associated with acid resistance or susceptibility. The culture medium affected growth rate and morphology: thin floating sheets of cells were observed in 7H9-OADC versus confluent, thick, waxy, and wrinkled pellicles in WR-GD. Culture medium pH affected growth rate (which was highest at pH 6.0), but it had little or no effect on D values for M. paratuberculosis at any test pH. When grown in 7H9-OADC, M. paratuberculosis was more acid resistant at all test pHs (higher D values) than when grown in WR-GD. Glycerol appeared to be the culture medium component most responsible for lower levels of M. paratuberculosis acid resistance. When glycerol was substituted for OADC in the 7H9 medium, D values were significantly lower than those of 7H9-OADC-grown M. paratuberculosis and were approximately the same as those for M. paratuberculosis grown in WR-GD medium. Comparison of the SDS-PAGE protein profiles for M. paratuberculosis cultures grown in 7H9-OADC, WR-GD, or 7H9-GD medium revealed that increased expression of 34.2- and 14.0-kDa proteins was associated with higher levels of acid resistance of M. paratuberculosis grown in 7H9-OADC medium and that 56.6- and 41.3-kDa proteins were associated with lower levels of acid resistance. This is the first report showing that in vitro culture conditions significantly affect growth characteristics, acid resistance, and protein expression of M. paratuberculosis, and the results emphasize the importance of culture conditions for in vitro susceptibility studies.  相似文献   

13.
This study aims to investigate the effects of Tween 80 on curdlan production, cell growth, and glucosyltransferase activity. The addition of Tween 80 to the culture medium increased curdlan production. However, curdlan production did not increase further when excessive Tween 80 (>0.3% Tween 80) was added to the culture medium. The addition of Tween 80 to the culture medium did not affect cell growth. The glucosyltransferase activity involved in the curdlan synthesis increased with the increase of Tween 80 concentration. The glucosyltransferase activity did not increase further when excessive Tween 80 (>0.3% Tween 80) was added to the culture medium. Maximum curdlan was observed at day 5 and then levelled off. The biomass continued to increase until the end of the experimental period (6 d). Maximum glucosyltransferase activity was also observed at day 5 and decreased thereafter. The results indicate that the enhanced curdlan production by Tween 80 is highly correlated with glucosyltransferase activity.  相似文献   

14.
The accuracy of the Bactec MGIT 960 system for susceptibility testing of 177 clinical isolates of Mycobacterium tuberculosis to first line drugs (isoniazid, rifampicin, ethambutol and streptomycin) was compared with the agar reference method. The sensitivity, the ability to detect resistance, of the MGIT system was 100%, while the specificity, the ability to detect susceptibility, ranged from 98.6% to 100% for all drugs tested.  相似文献   

15.
A sample comprising 40 H. influenzae and 74 H. parainfluenzae strains was used to verify methods for determining susceptibility to antibiotics. Modified Levinthal agar proved to be suitable for the agar dilution and agar diffusion method, while brain heart infusion with the thermally released components of sheep blood (X and V factor) and lysed horse blood performed well in the dilution micromethod. The iodometric method served well for beta-lactamase production. A substantial proportion of strains was resistant to penicillin, erythromycin, roxitromycin and sulfamethoxazole. Ampicillin susceptibility was of crucial importance. Resistance was largely due to beta-lactamase production. Since there are ampicillin-resistant strains which fail to produce beta-lactamase, it is necessary either to determine the MIC value or use a disk with 2 micrograms ampicillin. A disk containing 10 micrograms ampicillin may yield a false positive result.  相似文献   

16.
beta-Ionone, an aroma compound exhibiting flower notes, can be obtained from beta-carotene in a cooxidation system utilizing xanthine oxidase-generated reactive oxygen species (ROS). ROS have to be controlled as, although they can give rise to beta-ionone, they may also degrade it. In this work, the biotransformation of beta-carotene into beta-ionone was investigated in systems containing variable proportions of decane to extract beta-ionone before degradation. The use of 50% or 90% decane resulted in increased production yields. Tween 80, which was added to further improve the production, slightly decreased the reactivity of the medium and the extraction of beta-carotene, but increased the extraction of beta-ionone. In total, the addition of Tween 80 significantly improved the yields of conversion, which reached 34% with 50% decane and 2.5 g/L Tween 80 compared to 10% without decane and Tween 80. These results show that it is possible to control a ROS-mediated reaction by the addition of a solvent phase and by modifing the medium composition.  相似文献   

17.
Sixteen Bifidobacterium isolates from the human gastrointestinal tract were assayed for susceptibility to 44 antibiotics by soft agar overlay disc diffusion on TPY agar. Five isolates (3/7 B. bifidum and 2/3 B. breve ) exhibited atypical antibiotic susceptibility profiles. Poor growth in the agar overlay accounted for susceptibility of B. bifidum but not B. breve isolates. All other isolates were resistant to cefoxitin (30 μg), aztreonam (30 μg), vancomycin (30 μg), amikacin (30 μg), gentamicin (10 μg), kanamycin (30 μg), streptomycin (10 μg), fusidic acid (10 μg), trimethoprim (5 μg), norfloxacin (10 μg), nalidixic acid (30 μg), metronidazole (5 μg), polymyxin B (300 μg) and colistin sulphate (10 μg), and they were susceptible to the six penicillins studied, cephalothin (30 μg), cefuroxime (30 μg), cefaclor (30 μg), ceftizoxime (30 μg), cefotaxime (30 μg), bacitracin (10 μg), chloramphenicol (30 μg), erythromycin (15 μg), clindamycin (2 μg), rifampicin (5 μg) and nitrofurantoin (300 μg). In addition, they varied in their susceptibility to cephradine (30 μg), cephazolin (30 μg), cefoperazone (75 μg), ceftriaxone (30 μg), ofloxacin (5 μg) and furazolidone (15 μg). They were resistant, or only marginally moderately susceptible, to ceftazidime (30 μg), netilmicin (10 μg), sulphamethoxazole (100 μg), cotrimoxazole (25 μg) and ciprofloxacin (5 μg), and susceptible or marginally moderately susceptible to tetracycline (30 μg). All B. bifidum isolates were susceptible to cefixime (5 μg). Four micro-organism-drug combinations were evaluated for β-lactamase activity but its absence suggested that cell wall impermeability was responsible for cephalosporin resistance among bifidobacteria. The antibiotic susceptibility of B. animalis 25527T was similar to that of the human isolates.  相似文献   

18.
The authors compared conventional and Bactec determinations of pyrazinamide susceptibility with pyrazinamidase activity determined using either standard Dubos Oleic agar or Middlebrooks 7H9 agar. Of the 26 Mycobacterium tuberculosis tested, Bactec found 16 strains susceptible and 10 resistant, conventional methods found six susceptible and 20 resistant. Dubos identified 13 and Middlebrooks 10 strains as producing pyrazinamidase (susceptible). Of the 11 strains susceptible in Bactec and resistant by conventional methods, eight produced pyrazinamidase. All mycobacteria other than tuberculosis (6) and Mycobacterium bovis (2) were resistant by all methods. Bactec results gave a better correlation with pyrazinamidase results than conventional tests.  相似文献   

19.
A rapid (3-h) arylsulfatase assay for cell suspensions of mycobacteria, in which p-nitrophenyl sulfate is used as the substrate, was developed. Arylsulfatase activity was found in cell suspensions of representative strains of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum grown without the substrate in either Middlebrook 7H9 medium containing 0.2% (wt/vol) glucose and 0.05% (vol/vol) Tween 80 or Dubos broth medium, but was absent in cells grown in a low-pH, minimal medium containing 1% (vol/vol) Tween 80 as the sole carbon source. The levels of arylsulfatase activity of representatives of all three species were equal whether the activity was measured at pH 5.5, 6.5, or 7.5 and whether the cells were suspended in phosphate or Tris buffer. The addition of high levels of sulfate (present in the low-pH, Tween 80-containing medium) to Middlebrook 7H9 medium resulted in significantly lower levels of arylsulfatase activity in strains of M. scrofulaceum, but did not affect the levels in either M. avium or M. intracellulare. The levels of arylsulfatase activity were highest in M. avium, intermediate in M. intracellulare, and lowest in M. scrofulaceum strains. Polyacrylamide gel electrophoresis of crude extracts from late-log-phase cells of representatives of each species produced activity bands of unique mobility (one in M. avium, three in M. intracellulare [82, 5, and 13%], and two in M. scrofulaceum [60 and 40%]).  相似文献   

20.
The incidence of infections caused by staphylococci with decreased susceptibility to teicoplanin (MIC>/=8 microg/ml) is increasing, but the disk diffusion test has difficulty detecting this low level of resistance. In addition, detection is complicated because of the heterogeneous phenotypes for teicoplanin. In this study, we evaluated an agar screening method to detect staphylococci with decreased susceptibility to teicoplanin or heterogeneous resistance. First, to investigate the inoculum density and teicoplanin concentration of screening agar, we used 10(5) and 10(6) CFU/ml and Mueller-Hinton agars supplemented with 6 and 8 microg of teicoplanin/ml to test 39 genetically distinct staphylococcal strains (15 strains with teicoplanin MICs>/=8 microg/ml and 24 strains with teicoplanin MICs/=8 microg/ml or showing heteroresistance could be detected. These findings indicate that the method can be used as a reliable screening method for detecting staphylococci with reduced susceptibility to teicoplanin.  相似文献   

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