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Instituto Nacional de Enfermedades Respiratorias "Emilio Coni", resistencia a medicamentos, pruebas de sensibilidad microbiana, métodos, . strains were available in a median of 14 and 10 days from date of inoculation, respectively. Overall . Telefax: () [email protected] y [email protected] ordendelsantosepulcro.info Main · Videos; Dating coach birmingham uk population machine in bangalore dating · enfermedades microbianas yahoo dating · torsion spring manufacturers. yahoo and other mayor seach traumatized an idiots guide to dating abused victimized enfermedades microbianas spanish edition,settlements galore internet in.
En cambio, se ha prestado menor atencion a los sistemas puramente organicos.
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A tal efecto, han medido el ensanchamientode las lfneas por resonancia paramagnetica de los electrones en mezclas de radicales ionicos y de sus precursores. Las velocidades son tambien elevadas para algunos compuestos aromaticos sustituidos, como quinonas y nitrilos. Estas variaciones pueden vincularse con los resultados de recientes estudios del efecto de solvatacion sobre las constantes de acoplamiento hiperfinas.
Las investigaciones electroquimicas se efectuaron con corriente continua estabilizada para eliminar, algunas de las indeterminaciones inherentes a las tecnicas de relajacion electroquimica. Se utilizaron como electrodos discos giratorios a baja temperatura. Se examinan algunas explicaciones plausibles de estas discrepancias. V protivopolozhnost' jetomu chisto organicheskim sistemam udeljalos' dovol'no neznachitel'noe vnimanie.
Jeti izmerenija byli provedeny posredstvom jelektronnogo para- magnitnogo rezonansa EPR s perenosom izmerenij na smesi radikal'nyh ionov i ih mate- rinskih soedinenij. Nam takzhe udalos' izmerit' k0bm s takoj tochnost'ju, kotoraja pozvo- ljaet obnaruzhit' nebol'shie razlichija, vyzvannye, verojatno; molekuljarnoj strukturoj i sre- doj.
Nekotorye zame- shhennye aromaticheskie soedinenija, podobnye hinonam i nitrilam, takzhe javljajutsja ves'ma bystrymi. Jeti izmene- nija mozhno korrelirovat' blagodarja nedavnim issledovanijam jeffekta sol'vatacii na sverh- tonkie konstanty svjazi.
Nami special'no byl izmeren kjel dlja sistemy nitrobenzola v uslovijah, kotorye jeksperimental'no byli - pochti identichny uslovijam pri izuchenii EPR. Elektrohimicheskie issledovanija provodilis' metodom tverdogo sostojanija de s tem, chtoby iskljuchit' nekotorye neopredelennosti, pri- sushhie metodam jelektrohimicheskoj relaksacii.
For isoniazid resistance using fresh and old isolates, The proportion of nitrate reductase assay ambiguous results was significantly higher in multidrug-resistant than in non-multidrug-resistant isolates The nitrate reductase assay demonstrated provided reliable results for antibiotic resistance. However, using old cultures leds to a higher proportion of false sensitive results; furthermore, the nitrate reductase assay capability to detect multidrug-resistant tuberculosis decreased due to a higher proportion of non-interpretable results.
Mycobacterium tuberculosis, drug resistance, microbial sensitivity tests, methods, nitrate reductase. Describir el rendimiento del ensayo de nitrato reductasa para detectar tuberculosis multirresistente en la rutina de trabajo de un laboratorio de referencia con recursos limitados.
La experiencia con el ensayo de nitrato reductasa demuestra que produce resultados resistentes confiables. The spread of multidrug-resistant strains of Mycobacterium tuberculosis has become a major public health concern and poses a formidable challenge to tuberculosis control due to its complex diagnostic and treatment challenges. Conventional methods for drug susceptibility testing of Mycobacterium tuberculosis, such as the proportion method, the absolute-concentration method, and the resistance ratio method, are used globally but have a long turnaround time 1.
The time lag poses a significant threat to the patient, the community and health care workers. Several other promising techniques, genetic as well as phenotypic, have been recently reported 2,3. One affordable option for rapid drug resistance detection is the nitrate reductase assay NRA that uses colorimetric detection of nitrite as an indication of growth.
It requires neither elaborate equipment nor expensive substrates or reagents.
A recent review 4 pointed out that although nitrate reductase assay has been shown to be highly sensitive and specific in the detection of rifampicin and isoniazid resistance, additional studies are required to determine its performance in the target population, i. In a previous study carried out in our laboratory 5this technique was compared with other rapid drug susceptibility testing methods using a panel of 64 strains. The NRA appears as rapid, inexpensive, and easy to perform 5.
Nevertheless, the performance characteristics of drug susceptibility tests may change when moving from the research stage to implementation at a population level in actual public health practice 6.
The current study was designed to test the performance of nitrate reductase assay for rifampicin and isoniazid resistance detection in the routine workflow of a reference laboratory with limited resources. This laboratory routinely receives isolates from groups targeted for drug susceptibility testing, as defined by the National Tuberculosis Program norms. Materials and methods Strains and inoculum preparation The nitrate reductase assay was evaluated in Mycobacterium tuberculosis complex isolates referred to the laboratory for drug susceptibility testing.
They were obtained from patients who were at high risk of multidrug-resistant tuberculosis, as specified the National Tuberculosis Program norms, with the following critera: All clinical isolates were tested prospectively in a blind manner for both nitrate reductase assay and the proportion method on Lowenstein Jensen, which served as the reference standard. Tubes were vigorously agitated and clumps were allowed to settle for 30 min. The supernatants were then adjusted with distilled water to equal the density of 1.
The reference strain H37Rv was tested in parallel. Antituberculous drugs Rifampicin, isoniazid, ethambutol and streptomycin were obtained in a powdered formulation from Sigma Chemical Co.
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Proportion method The proportion method was performed on Lowenstein Jensen medium according to Canetti et al. The results were read for the first time on 28th day. If this reading demonstrated resistance, no further readings were required. If the result of the first reading was susceptible, a second and final reading was made on day The results from the proportion method served as the reference standard.
Nitrate reductase assay The nitrate reductase assay was performed as described Angeby et al. Briefly, the antibiotic was included in the Lowenstein Jensen medium at a concentration of: Part of the inoculum was adjusted to equal the density of the No 1.
For each isolate, 0. If the color changed to pink, then tubes with drugs were tested.ENFERMEDADES BACTERIANAS
An isolate was considered resistant if the color change in the drug-tube was greater than in the 1: Drug-free control tubes that did not show any color change were further incubated and the procedure repeated at day 10 and day Non-interpretable results were defined as those obtained when isolates failed to show any color change in the drug-free control tube even at day Data analysis Statistical analyses were carried out with Epi Info version 6.
Factors associated with non-interpretable nitrate reductase assay results were also examined. Variables analyzed included multidrug-resistant status and time in days from the specimen culture to nitrate reductase assay inoculation 2 groups: Results A total of specimens were received from patients. Results of 39 isolates Among the remaining isolates, 81 Of the rifampicin-resistant strains, Of the isolates that had available results by the proportion method, The comparison data comparing the nitrate reductase assay with the conventional proportion method are shown in table 1.
Nitrate reductase assay results in detecting multidrug-resistant and non-multidrug resistant strains were available in a median of 14 and 10 days from date of inoculation, respectively.
Overall, the median time for the availability of the results was 10 days. The sensitivity of the nitrate reductase assay was as follows: The overall agreement between the nitrate reductase assay and the proportion method was Rifampicin and isoniazid sensitivities were much lower than anticipated from previous studies 4. Upon nitrate reductase assay repetition of those isolates formerly classified as false-susceptible, we found that using fresh subcultures of the 9 isolates classified as false-rifampicin susceptible strains, 4 could be classified as resistant.
Similarly, 5 of the 11 false-isoniazid susceptible strains were re-classified as resistant. These data gave an new overall sensitivity of All of the re-classified false-susceptible results were formerly obtained using isolates more than 70 days intervened between specimen culture to assay inoculation. This suggested that the low day. This suggested that the low levels of sensitivity previously obtained using the Mycobacterium tuberculosis isolates as they arrived regardless of previous manipulation or culture maintenance conditionsappeared to be related to the the period from specimen culture to nitrate reductase assay inoculation.
For isoniazid resistance a similar data trend was seen [ Overall, 23 of the 7. These non-interpretable results were more common among multidrug-resistant strains 13 of 74; Furthermore, no associations were discerned between the time in days from the specimen culture to nitrate reductase assay inoculation 2 groups: Discussion This study assessed the performance of the nitrate reductase assay on a population at risk of multidrug-resistant tuberculosis prevalence of multidrug-resistant, It provided support for the findings of earlier studies made on isolates maintained at low temperaturesas the evaluation was made under more controlled methodological conditions.