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M K Hourfar

Publications and source records attributed to M K Hourfar.

5 recordsLinked to original sources
PubMed2006

FACS technology used in a new rapid bacterial detection method.

Culture methods for bacterial detection (BacT/ALERT or Pall eBDS) are currently implemented in blood donor screening procedures in many countries. Experience in the first years after implementation of these detection assays showed that although the analytical sensitivity was extremely high (about 1 CFU mL(-1)), the majority of these platelets were still transfused before a positive screening result was attained. Rapid technologies were developed to more effectively prevent transfusion-transmitted bacterial infection. In this study, a new rapid bacterial detection method based on fluorescence-activated cell sorting (FACS) technology was developed. Bacteria were stained with thiazole orange dye for 5 min and measurement was taken immediately after staining. The entire process took only 30 min. Six transfusion-relevant bacteria strains were tested in a spiking study. Without pre-incubation in a special bacteria growth medium, analytical sensitivity ranged between 10(5) CFU mL(-1) (Klebsiella oxytoca and Serratia marcesens) and 10(3) CFU mL(-1) (Escherichia coli). Sensitivity could be improved to 10(1) CFU mL(-1) for all tested bacteria by adding a pre-incubation step (6 h at 37 degrees C). Although preliminary in nature, results of our study suggest that bacterial detection by FACS technology in conjunction with a pre-incubation step offers a sensitive alternative technology to culture methods. Additionally, it provides the benefit of a rapid test time and the opportunity of preventing bacterial transmitted infections more effectively.

Bacteriological Techniques↗
PubMed2006

Fluorescence quencher improves SCANSYSTEM for rapid bacterial detection.

BACKGROUND AND OBJECTIVES: The optimized scansystem could detect contaminated platelet products within 24 h. However, the system's sensitivity was reduced by a high fluorescence background even in sterile samples, which led to the necessity of a well-trained staff for confirmation of microscope results. MATERIALS AND METHODS: A new protocol of the optimized scansystem with the addition of a fluorescence quencher was evaluated. Pool platelet concentrates contaminated with five transfusion-relevant bacterial strains were tested in a blind study. RESULTS: In conjunction with new analysis software, the new quenching dye was able to reduce significantly unspecific background fluorescence. Sensitivity was best for Bacillus cereus and Escherichia coli (3 CFU/ml). DISCUSSION: The application of a fluorescence quencher enables automated discrimination of positive and negative test results in 60% of all analysed samples.

Bacteriological Techniques↗
PubMed2006

Anti-HBc screening of blood donors: a comparison of nine anti-HBc tests.

BACKGROUND AND OBJECTIVES: Since voluntary introduction of hepatitis B virus (HBV) minipool nucleic acid amplification technology (NAT) at the German Red Cross, the expected residual risk of a transfusion-associated HBV infection has been estimated to be 1 : 500,000 - about 10 times higher than for human immunodeficiency virus (HIV) or hepatitis C virus (HCV) infection. Donors demonstrating chronic positivity for antibody to hepatitis B core antigen (anti-HBc), negativity for hepatitis B surface antigen (HBsAg) and polymerase chain reaction (PCR)-negative with a low virus load are a major cause of this increased risk. MATERIALS AND METHODS: Ten-thousand blood donors from our blood-donation centre were screened for anti-HBc using the current PRISM HBc and the new PRISM HBcore assay to evaluate the diagnostic sensitivity and specificity of these tests. PRISM HBc- or PRISM HBcore-reactive samples were further analysed using seven additional tests for anti-HBc, two tests for antibody to hepatitis B surface antigen (anti-HBs), one test for antibody to hepatitis B envelope antigen (anti-HBe) and three HBV NAT assays. RESULTS: From a total of 10,000 donors, nine and 14 samples were reactive only in the PRISM HBc and the PRISM HBcore, respectively, whereas 165 samples were reactive in both anti-HBc assays. Further analysis of these 188 anti-HBc-reactive specimens in a total of nine different anti-HBc assays revealed concordant results for 162 (86.2%) specimens. Sample cut-off values for anti-HBc were significantly (P < 0.01) lower for anti-HBc-only reactive samples compared with specimens that were also reactive for anti-HBs or anti-HBe. CONCLUSIONS: Both PRISM anti-HBc assays revealed that approximately 1.8% of non-prescreened blood donors from Germany were reactive for anti-HBc. Although sensitivity was comparable between both assays, specificity was increased significantly with the PRISM HBcore. High anti-HBc sample cut-off values were indicative for reactivity in other HBV parameters and for concordant results in the nine different anti-HBc assays. Look-back investigations are necessary to estimate the infection risk both of anti-HBc-only positive and of anti-HBc/anti-HBs-positive blood transfusions.

Blood Donors↗
PubMed2005

Evaluation of an automated high-volume extraction method for viral nucleic acids in comparison to a manual procedure with preceding enrichment.

BACKGROUND AND OBJECTIVES: Nucleic acid extraction still harbours the potential for improvements in automation and sensitivity of nucleic acid amplification technology (NAT) testing. This study evaluates the feasibility of a novel automated high-volume extraction protocol for NAT minipool testing in a blood bank setting. MATERIALS AND METHODS: The chemagic Viral DNA/RNA Kit special for automated purification of viral nucleic acids from 9.6 ml of plasma by using the chemagic Magnetic Separation Module I was investigated. Analytical sensitivity for hepatitis C virus (HCV), human immunodeficiency virus-1 (HIV-1), hepatitis B virus (HBV), hepatitis A virus (HAV) and parvovirus B19 (B19) was compared to our present manual procedure that involves virus enrichment by centrifugation. RESULTS: Chemagic technology allows automation of the viral DNA/RNA extraction process. Viral nucleic acids were bound directly to magnetic beads from 9.6-ml minipools. By combining the automated magnetic beads-based extraction technology with our in-house TaqMan polymerase chain reaction (PCR) assays, 95% detection limits were 280 IU/ml for HCV, 4955 IU/ml for HIV-1, 249 IU/ml for HBV, 462 IU/ml for HAV and 460 IU/ml for B19, calculated for an individual donation in a pool of 96 donors. The detection limits of our present method were 460 IU/ml for HCV, 879 IU/ml for HIV-1, 90 IU/ml for HBV, 203 IU/ml for HAV and 314 IU/ml for B19. CONCLUSIONS: The 95% detection limits obtained by using the chemagic method were within the regulatory requirements for blood donor screening. The sensitivities detected for HCV, HBV, HAV and B19 were found to be in a range similar to that of the manual purification method. Sensitivity for HIV-1, however, was found to be inferior for the chemagic method in this study.

Automation↗