A morphological study of the action of equine anti-lipopolysaccharide plasma on gram-negative bacteria

Department of Physiology. University of Natal Medical School, P.O. Box 17039, Congella, 4013, South Africa Received September 3, 1986 Accepted November 14, 1986 Three strains of gram-negative bacteria—one each of Escherichia coli, Klebsiella pneumoniae and Enterobacter sp. —were treated with anti-lipopolysaccharide hyperimmune equine plasma (anti-LPS) or nun-immune control plasma and examined by scanning electronmicroscopy. Within a few minutes of treatment with anti-LPS, bacteria were agglutinated. Evidence of cell membrane destruction was observed shortly thereafter and total cell disintegration and disruption occurred within 1–2 h. In contrast, non-immune plasma had no effect on cell morphology. This confirms the findings in previous microbiological studies that specific antibodies in anti-LPS bind to lipopolysaccharide (LPS endotoxin), and thereby initiate the destruction of gram-negative bacteria.