A PCR-colorimetric microwell plate hybridization assay for detection of Mycobacterium tuberculosis and M. avium from culture samples and Ziehl-Neelsen-positive smears.
(25/1676)
Differentiation between Mycobacterium tuberculosis and M. avium is essential for the treatment of mycobacterial infections. We have developed an easy and rapid detection assay for the diagnosis of mycobacterial diseases. This is a PCR-hybridization assay based on selective amplification of a 16S rRNA gene sequence using pan-Mycobacterium primers followed by hybridization of the amplification products to biotinylated M. tuberculosis and M. avium-specific probes. A total of 55 mycobacterial isolates were tested. For all isolates, results concordant with those of conventional identification methods were obtained. Moreover, we developed a method for extraction of DNA from Ziehl-Neelsen-positive smears which allows the recovery of intact target DNA in our PCR-hybridization assay. Our method was able to confirm all culture results for 59 Ziehl-Neelsen-positive smears from clinical specimens (35 sputum, 11 lymph node biopsy, 6 stool, 4 pus, 2 urine, and 1 pericardial fluid specimens). These data suggest that our PCR-hybridization assay, which is simple to perform and less expensive than commercial probe methods, may be suitable for the identification of M. tuberculosis and M. avium. It could become a valuable alternative approach for the diagnosis of mycobacterial infections when applied directly to DNA extracted from Ziehl-Neelsen-positive smears as well. (+info)
In vitro susceptibility of Cryptococcus neoformans isolates to five antifungal drugs using a colorimetric system and the reference microbroth method.
(26/1676)
Minimum inhibitory concentrations (MICs) of amphotericin B, 5-flucytosine, fluconazole, itraconazole and ketoconazole were determined against 42 clinical isolates of Cryptococcus neoformans var. neoformans using the Alamar YeastOne colorimetric method and the NCCLS reference microdilution method. No strains with resistance to amphotericin B, itraconazole or ketoconazole were detected with either method. Using the reference method, the MICs of fluconazole were >/= 64 mg/L, whereas using the colorimetric method all MICs were >/=16 mg/L. The MIC values of 5-flucytosine were also higher using the reference method (8-16 mg/L for 32% of isolates) compared with the colorimetric method. The percentage of agreement between the methods, using a difference of two dilutions, was 70.7% for itraconazole, 73.2% for amphotericin B, 80% for fluconazole, 88% for 5-flucytosine and 95% for ketoconazole. Overall, we conclude that for fluconazole and 5-flucytosine, in a low but not insignificant number of isolates, results with the two methods are discordant, some isolates being found sensitive with the colorimetric test, but resistant with the reference method. (+info)
Absence of oroticaciduria in adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency.
(27/1676)
Orotic acid excretion was normal when tested by three methods in adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency. These results do not support the speculation, based on the oroticaciduria observed by others, that the immunodeficiency in these disorders results from the inhibition of pyrimidine biosynthesis. An alternative hypothesis is discussed. (+info)
Comparison of a new colorimetric assay with the NCCLS broth microdilution method (M-27A) for antifungal drug MIC determination.
(28/1676)
We evaluated a new microtiter assay for antifungal susceptibility testing based on a colorimetric reaction to monitor fungal substrate utilization. This new method (rapid susceptibility assay [RSA]) provides quantitative endpoint readings in less than 8 h compared with visual determination of MIC by the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution method, which requires a minimum of 48 h of incubation. In this study, we tested clinical isolates from each of the following species: Candida albicans (20 isolates), C. glabrata (20 isolates), C. krusei (19 isolates), C. tropicalis (19 isolates), and C. parapsilosis (28 isolates). RSA and NCCLS broth dilution methods were used to determine the MICs of amphotericin B, fluconazole, itraconazole, and 5-flucytosine for all 106 isolates. RPMI 1640 medium buffered with morpholinopropanesulfonic acid was used for both methods; however, glucose and inoculum concentrations in the RSA were modified. RSA MICs were determined as the lowest drug concentration that prevented glucose consumption by the organism after 6 h of incubation. MICs obtained from the RSA were compared with those obtained from the NCCLS M-27A method read at 24 and 48 h. MIC pairs were considered in agreement when the difference between the pairs was within 2 twofold dilutions. For the 106 isolates tested, amphotericin B and 5-flucytosine demonstrated the highest agreement in MICs between the two methods (100 and 98%, respectively), whereas fluconazole and itraconazole produced less favorable MIC agreement (63.2 and 61.3%, respectively). The azole MIC differences between the two methods were significantly reduced when lower inocula were used with a prolonged incubation time. This preliminary comparison suggests that this rapid procedure may be a reliable tool for the in vitro determination of MICs of amphotericin B and 5-flucytosine and warrants further evaluation. (+info)
Physico-chemical properties and hydrolysis of oxprenolol octanoyl and benzoyl esters.
(29/1676)
The kinetics of hydrolysis of octanoyl ester of oxprenolol (O-OXP) and benzoyl ester of oxprenolol (Benz-OXP) has been investigated in aqueous solution at 310 K over the pH range 0.42-9.5. The decomposition was followed by UV spectral method. At the pH range 0.42 to 9.5, hydrolysis of oxprenolol esters (E-OXP) consists of hydrolysis of BH+ molecules catalyzed by hydrogen ions, spontaneous hydrolysis of BH+ molecules and hydrolysis of BH+ and B molecules catalyzed by hydroxide ions. Various buffer substances were found to exhibit general acid and base catalysis of the degradation. (+info)
Effects of iron and copper ions on the inducibility of hydrogen peroxide in E. coli.
(30/1676)
Inducing capacities of hydrogen peroxide in SOS chromotest were investigated in the absence and in the presence of iron and copper ions. Strain PQ37 of Escherichia coli and two strains with altered protection against oxidative damage (PQ300 and OG400) were employed. The latter two strains were more sensitive to the hydrogen peroxide inducing activity than strain PQ37. At the concentration of 150 nmol/ml and 300 nmol/ml, iron ions induced SOS response. At the concentration range from 30 nmol/ml to 300 nmol/ml iron enhanced the effects produced by H2O2. Results with copper were negative. (+info)
8-Difluoromethoxy-4-quinolone derivatives as anti-feline immunodeficiency virus (FIV) agents: important structural features for inhibitory activity of FIV replication.
(31/1676)
The inhibitory activities of various 8-difluoromethoxy-4-quinolone derivatives against feline immunodeficiency virus (FIV) replication in the chronically infected cell line P-CrFK were investigated. Certain derivatives were found to inhibit FIV production from P-CrFK cells in a dose-dependent manner without exhibiting cytotoxic effects at inhibitory concentrations. Based on this study, the structures important for anti-FIV activity are suggested to be (i) a carboxyl group at position C-3, and (ii) an aromatic modification at position 4 of the C-7 piperazinyl moiety. (+info)
A colorimetric detection system for Calymmatobacterium granulomatis.
(32/1676)
OBJECTIVE: To incorporate the first polymerase chain reaction (PCR) assay for Calymmatobacterium granulomatis into a colorimetric detection system for use in routine diagnostic laboratories. METHODS: A capture oligonucleotide specific for the Klebsiella phoE gene was covalently linked to tosyl activated magnetic beads. Biotinylated phoE PCR products obtained from 14 positive specimens from patients with donovanosis and isolates of Klebsiella pneumoniae, K rhinoscleromatis, and K ozaenae were cleaved with HaeIII for the purpose of differentiation, captured by the prepared beads, and subjected to standard EIA detection methodology. Eight samples from unrelated genital conditions underwent the same procedure. It was anticipated from the sequence data that the biotinylated fragment would be cleaved from the capture oligonucleotide target region in the three Klebsiella phoE products (that is, a negative colorimetric result) while the entire fragment of interest would remain intact in the positive C granulomatis phoE products (that is, a positive colorimetric result). RESULTS: All 14 positive specimens from patients with donovanosis gave strong colorimetric readings with this detection system. Isolates of K pneumoniae, K rhinoscleromatis, K ozaenae, and the eight specimens from unrelated genital conditions were negative. CONCLUSION: The successful development of a colorimetric detection system for C granulomatis incorporating two levels of specificity enables the molecular diagnosis of this condition to be undertaken by routine diagnostic laboratories. This should have an important role in the Australian government's campaign to eradicate donovanosis by 2003 though the test still needs to undergo trials and be validated using a larger number of samples from geographically diverse parts of the world in order to ascertain the generalisability of the methodology. (+info)