sodium-dodecyl-sulfate and Acquired-Immunodeficiency-Syndrome

The multiple-drug-resistance property of Mycobacterium avium complex (MAC) is mainly attributed to a cell envelope permeability barrier. MAC treated with subinhibitory levels of dimethyl sulfoxide (DMSO) and ethylenediaminetetraacetic acid (disodium salt) (EDTA) did not have altered minimum inhibitory concentration (MIC) levels or show ultrastructural changes; the effect of sodium dodecyl sulfate (SDS) was variable. With SDS, the visualization of the nucleoid and ribosomes decreased, and amorphous electron-dense material accumulated near the structurally altered cytoplasmic membrane and cell wall. Use of 0.005% Tween-80 resulted in a 2-4-fold reduction in MIC in the case of rifampicin, ansamycin (LM 427), cephapirin, and ciprofloxacin. Tween-80 treated cells were swollen, and deposits of low electron-density accumulated in the cytoplasm; distortions in the outer-cell integuments were observed. These findings are consistent with the idea that Tween-80 increases cell-envelope permeability, thereby enhancing drug penetrability and reducing MIC levels. Because of the action of Tween-80, its use in drug-susceptibility media or diluent fluids should be avoided.

Topics: Acquired Immunodeficiency Syndrome; Anti-Bacterial Agents; Dimethyl Sulfoxide; Drug Synergism; Edetic Acid; Humans; Microbial Sensitivity Tests; Mycobacterium avium Complex; Sodium Dodecyl Sulfate; Surface-Active Agents

Three commercially available ELISA test kits were used for the detection of antibodies to HTLV-III, the cause of AIDS. Positive results were confirmed by means of the Western Blot. In the course of our routine diagnostic studies, a total of 112 infections with HTLV-III were found among persons in high-risk groups or in blood donors, of whom only 13 presented the clinical picture of AIDS. About 20% of all seropositive persons were intravenous drug addicts. Upon comparison of the ELISA kits of Abbott, Organon, and Sorin, no conclusive indication of a false negative result has been obtained to date with any test kit. Differences were, however, found as regards the number of repeatedly positive samples that could not be confirmed in the Western Blot. The highest rate of these false positive results was found with the Abbott-ELISA, followed by Sorin, while the Organon test did not yield a single false positive result. The lack of agreement in a certain percentage of the tested samples is probably caused by differences in the cut-off values of the various ELISAs used. This value is chosen in such a manner that false positive results are avoided, while even low levels of antibodies are still detected. Since there was no evidence of false negative results, all three kits are suitable for HTLV-III screening of sera. Our results show the need for confirmation of positive results with ELISA by means of the Western Blot.

Topics: Acquired Immunodeficiency Syndrome; Antibodies, Viral; Deltaretrovirus; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Humans; Reagent Kits, Diagnostic; Risk; Sodium Dodecyl Sulfate