Neutrophil function in gram-negative rod bacteremia. The interaction between phagocytic cells, infecting organisms, and humoral factors.

Abstract

A B S T R A C T To assess the phagocytic and bactericidal function of neutrophils in the acute stages of gramnegative rod bacteremia, cells from 30 nonleukopenic patients were studied in a test system utilizing plasma obtained simultaneously with culture-positive blood, the autologous infecting strain, and two laboratory test strains of Staphylococcus aureus and Pseudomonas aeruginosa. Results were compared to those obtained with normal neutrophils and plasma. Patient and control plasma were simultaneously tested with each source of phagocytic cells to localize any abnormalities. Four patients had a defect against their infecting strain, 33% of the inoculum phagocytized and killed versus 80% by controls. In these cases differences were localized to the patients' plasma, as normal plasma tested with patients' cells reversed the defect. Thus, four patients had impaired opsonization when compared to normal controls, but we also observed that 11 of 30 bacteremic isolates, all Escherichia coli, showed absolute or relative resistance to phagocytosis in the patient and control assay system. No intrinsic granulocyte killing abnormalities were noted. There was poor correlation between results obtained with infecting strains compared to laboratory test organisms. We conclude that in patients without evidence of an inherited neutrophil bactericidal disorder, recurrent infection, or treatment with cytotoxic drugs, intrinsic bactericidal defects are uncommon at the onset of gram-negative bacteremia, and impaired opsonization is the most commonly encountered cause of neutrophil dysfunction.

Escherichia coliin extra-intestinal infections

“…Specific 0 antisera did not increase phagocytosis, while K antibodies, did, according to Sjostedt (1946). Weinstein & Young (1976 found that Ki-containing strains from bacteraemia were relatively more resistant to opsonophagocytosis by normal human plasma and polymorphonuclear leucocytes than non-K 1 strains. Addition of K antibody increased the phagocytosis of K 1 bacteria, and the authors suggested that the low immunogenicity of the K1 antigen could explain the resistance to phagocytosis in normal plasma.…”

Decreased Heat-Labile Opsonic Activity and Complement Levels Associated with Evidence of C3 Breakdown Products in Infected Pleural Effusions

“…The role of complement has been clearly established experimentally (5,6) and indirectly confirmed in clinical situations by the demonstration ofdecreased opsonic activity in patients with C3 deficiency, and concomitant increased susceptibility to bacterial infections (7). Several clinical studies have also shown that serum complement levels and(or) opsonic activity could be depressed during acute septicemia (8)(9)(10). It could be therefore hypothesized that persistence of microorganisms in presence of PMN-s, as encountered in infected pleural effusions, might be a result of inadequate, complement-dependent opsonization of the infectious agent.…”

Evaluation of the Scansystem method for detection of bacterially contaminated platelets

“…Bacterial counts at 30 hours varied considerably, but this did not affect the ability of the Scansystem to provide positive results. This is likely to be due to the fact that the Scansystem can detect both live and dead bacteria, so that the presence of bacterial species such as P. aeruginosa and S. epidermidis , which are frequently inhibited or killed in the presence of human plasma, 7,8 can still be detected provided some bacterial growth occurred. This is particularly important for contamination with P. aeruginosa because transfusion of small amounts of endotoxin produced by the growth of this organism can result in a fatal outcome.…”