Biomedical subjects

P Prendes

Publications and source records attributed to P Prendes.

6 recordsLinked to original sources

PubMed1999

Fully automated liquid culture system compared with Löwenstein-Jensen solid medium for rapid recovery of mycobacteria from clinical samples.

The aim of this study was to compare the rate of recovery of mycobacteria and the time to detection in 5208 samples using the MB/BacT culture system (Organon Teknika, USA) and Löwenstein-Jensen medium. Mycobacteria were recovered from 301 (5.7%) samples. Two hundred fifty-seven (85.3%) isolates from 114 patients were Mycobacterium tuberculosis [135 (52.5%) smear-positive, 122 (47.4%) smear-negative], and 44 (14.6%) were potentially pathogenic environmental mycobacteria. The yield with the MB/BacT was higher than that with Löwenstein-Jensen [287 (95.3%) vs. 200 (66.4%), P<0.001] for both Mycobacterium tuberculosis [247 (96.1%) vs. 187 (72.7%), P<0.001] and potentially pathogenic environmental mycobacteria [40 (90.9%) vs. 13 (29.5%), P<0.001], mainly at the expense of the smear-negative samples. Moreover, 70 (27.2%) samples were positive only in the MB/BacT, whereas ten (3.8%) samples were positive only in Löwenstein-Jensen. The number of patients with tuberculosis detected by the MB/BacT was higher than that detected by Löwenstein-Jensen medium [111 (97.3%) vs. 89 (78%), P<0.001]. In 25 (21.9%) patients the diagnosis was established solely by means of the MB/BacT. In smear-positive and smear-negative samples, the mean times to detection of Mycobacterium tuberculosis were 16.7 and 26.3 days, respectively, with Löwenstein-Jensen and 11.5 and 19.3 days, respectively, with the MB/BacT. These results indicate that the MB/BacT is more efficient and faster than Löwenstein-Jensen for the recovery of mycobacteria.

Bacteriological Techniques↗

PubMed1998

Cis/Trans Reactivity: Epoxy-Amine Systems.

The reactivities of cis and trans isomers of 1,2-diaminocyclohexane (1,2-DCH)/epoxy resin were studied separately. We found that the primary amine hydrogen disappears in both isomers at a similar rate when they react with an epoxy resin. However, the formation of tertiary amines differs considerably. The reactivity of the second amine hydrogen for the trans isomer is greater than that for the cis isomer, and this difference is observed as the reaction proceeds. The main reason for the slower disappearance of the cis secondary amine is steric hindrance and this fact is observed in the preexponential factors, glass transition temperatures (Tg), and ratio of rate constants of secondary to primary amine (R). The reaction was followed by Fourier transform infrared spectroscopy in the near-infrared range. The values of Tg were obtained by differential scanning calorimetry.

Journal Article↗

PubMed1998

Comparison of the ligase chain reaction with solid and liquid culture media for routine detection of Mycobacterium tuberculosis in nonrespiratory specimens.

The aim of this study was to compare the results of a commercial assay based on the ligase chain reaction [(LCR) LCx Probe System MTB; Abbott, USA] with those of culture in liquid medium (Septi-Chek AFB; Becton-Dickinson, USA) and culture on the egg-based Löwenstein-Jensen solid medium for the direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens. The results were analyzed according to the standard definition of a true-positive result. Two hundred thirty-five nonrespiratory samples routinely submitted to rule out tuberculosis were analyzed. All samples were smear-negative. Mycobacterial growth in either culture medium was detected in 18 (7.6%) specimens: Mycobacterium tuberculosis was recovered from seven (38.9%) specimens cultured on Löwenstein-Jensen medium and from 18 (100%) specimens cultured in Septi-Chek AFB. The LCR protocol was positive in 22 specimens. None of the LCR-negative controls showed positive results. All samples positive by culture on Löwenstein-Jensen medium were positive by culture in liquid medium and by the LCR assay. However, Mycobacterium tuberculosis was detected by culture in liquid medium in two specimens that were negative by the LCR assay, whereas six specimens negative by culture in liquid medium were positive by the LCR protocol; three of these were identified as true-positive results of the LCR assay. The sensitivity, specificity, and positive and negative predictive values were 33.3%, 100%, 100%, and 93.8%, respectively, for Löwenstein-Jensen medium; 85.7%, 100%, 100%, and 98.6% for the liquid medium; and 90.4%, 98.5%, 86.3%, and 99% for the LCR assay. These findings indicate that the LCR assay may be a valid method of high diagnostic yield for direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens.

Body Fluids↗

PubMed1997

Comparison of MB-check and Löwenstein-Jensen media for recovery of mycobacteria.

We have compared the rate of recovery of mycobacteria with the MB-Check culture system (liquid phase) and the Löwenstein-Jensen (LJ) medium in 2,907 clinical specimens obtained from 830 patients submitted for mycobacterial culture during 1-year period. Direct smear examination was carried out by auramine-rhodamine staining. All primary isolates from the culture media were confirmed by Ziehl-Neelsen staining and identified by acridinium-ester-labeled DNA probes specific for Mycobaterium tuberculosis complex. A total of 214 isolates were of the M. tuberculosis complex (88 patients) and 54 of "potentially pathogenic environmental mycobacteria" (45 patients). A total of 117 (54.7%) samples were smear-positive and the remaining 97 (45.3%) were smear-negative. There was a significant difference in the percentage of positive cultures obtained by the MB-Check method (99.1%) as compared with the LJ medium (73.8%) (P < 0.05). This difference, however, occurred almost exclusively at the expense of the 97 smear-negative samples (positive cultures 97.95% by the MB-Check method vs. 42.3% by the LJ culture, P < 0.05). The number of patients diagnosed of tuberculosis by the MB-Check was significantly higher as compared with LJ medium (88 [100%] vs. 77 [87.5%], P < 0.05). In 11 (12.5%) patients, the diagnosis was only established by the MB-Check system. In smear-positive samples, the mean (+/-SD) detection time for M. tuberculosis complex was 14.8 +/- 8 days with MB-Check and 19.9 +/- 7 days with LJ medium. The corresponding figures in smear-negative samples were 22.8 +/- 3 days and 27.8 +/- 6 days, respectively. DNA probes directly applied to MB-Check liquid medium showed a sensitivity of 98.8% and specificity of 100%. These results indicate that the MB-Check system is more efficient for the recovery of mycobacteria than LJ medium.

Bacterial Typing Techniques↗

PubMed1996

Comparison of solid and liquid culture media with polymerase chain reaction for detection of Mycobacterium tuberculosis in clinical samples.

The aim of this study was to determine the sensitivity of different methods--two commercial polymerase chain reaction (PCR) kits (a protocol of nested PCR and a protocol of amplification of the IS6110 insertion element), the radiometric Bactec system, the Septi-Chek AFB culture system, and culture in Löwenstein-Jensen (LJ) solid medium--for the detection of Mycobacterium tuberculosis. One hundred clinical samples from 51 patients with culture-positive tuberculosis (81 specimens) and 19 controls (19 specimens) were used. Eighty-nine percent of the samples were smear negative. In the 81 specimens obtained from patients with tuberculosis, the frequency of positivity was 66.6% for nested PCR, 63% for culture in liquid media, 38.3% for IS6110 assay, and 28.4% for culture in LJ medium. In 18 samples obtained by invasive procedures in patients with tuberculosis, mycobacterial DNA was detected by nested PCR in 83.3% (including all samples positive by culture on liquid media), by culture in liquid media in 77.7% by culture on LJ medium in 27.7%, and by the IS6110 assay in 11.1%. No false-positive results were obtained from the negative control specimens with any of the techniques tested. The sensitivity of the reamplification protocol appears to be superior to that of the IS6110 assay and similar to that of the Bactec system.

Culture Media↗

PubMed1981

Comparative studies of two systems of prophylactic antibiotics in head and neck surgery.

One hundred and seventeen patients undergoing operations on the head and neck were investigated for the causes of infection. There was a close relationship between the pre-operative culture and the risk of infection. There was a greater risk of infection (10.7%) when the pharynx was opened than when it was not (0.0%). The operations most liable to infection are laryngopharyngectomy and those in which skin flaps are used. The isolation of pathogenic bacteria in the operative exudate did not in general predispose to the development of infection, which did not occur when these cultures were negative. Positive cultures obtained from the drain on 3 consecutive days were a significant indication that infection will probably occur.

Anti-Bacterial Agents↗