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The efficacy of benzalkonium chloride and sodium hypochlorite against Acanthamoeba polyphagaand two Tetrahymenaspp. was determined based on the European Standard EN 1276:2009 suspension test. Trophozoite viability was assessed by determination of the membrane integrity using flow cytometry as a fast screening technique. Bovine serum albumin was added to simulate clean (0.3 g/liter) and dirty (3 g/liter) conditions. Benzalkonium chloride caused cell lysis at concentrations above 50 mg/liter under clean and dirty conditions. A concentration of 50 mg of free chlorine per liter had a strong biocidal effect on acanthamoebae and tetrahymenae after 15 min under clean and dirty conditions. Our results suggest that benzalkonium chloride and sodium hypochlorite were effective against the three microorganisms at concentrations commonly applied in the food industry.

ABSTRACTIn the context of a larger clinical study in Nouna, Burkina Faso, we evaluated a simplified dual-platform (DP) flow cytometric (FCM) method that allows the determination of major lymphocyte subsets in a single test tube. We compared the phenotyping of lymphocytes with DP FCM and simultaneous measurements with standard single-platform (SP) FCM for samples from 177 individuals. Analysis of the comparative measurements revealed that DP FCM systematically underestimates the proportion of NK cells, overestimates the percentage of CD3+CD8+lymphocytes, and yields proportions of B cells and CD4+T cells comparable with the results from SP FCM. Bland-Altman analysis showed a low bias between both methods and an acceptable precision for percent values of CD4+T cells (bias ± precision, -1% ± 6%) and CD8+T cells (-3% ± 6%). The absolute cell numbers of all lymphocyte subpopulations, however, were systematically biased towards lower values being obtained by DP FCM. Reference values for the distribution of T-cell maturation phenotypes in 177 healthy adults were calculated using DP FCM. The mean ± standard deviation (SD) CD4+-to-CD8+T-cell ratio was 1.61 ± 0.61, the mean percentage ± SD of CD4+T cells was 42% ± 7%, and that of CD8+T cells 29% ± 7%. Among CD4+lymphocytes, 28% ± 7% were classified as central memory (CD45RAlowCCR7+), 22% ± 10% as nai¨ve (CD45RAhighCCR7+), 45% ± 12% as effector memory (CD45RAlowCCR7-); and 5% ± 3% as terminally differentiated effector memory expressing CD45RA (CD45RAhighCCR7-). Among CD8brightlymphocytes, 3% ± 2% had a central memory phenotype, 27% ± 13% were nai¨ve, 37% ± 13% had an effector memory phenotype, and 34% ± 12% were terminally differentiated effector memory cells expressing CD45RA.