Assessment of the enzymuria resulting from gentamicin alone and combinations of gentamicin with various beta-lactam antibiotics.

OBJECTIVE: To determine the propensity of beta-lactam antimicrobials to ameliorate or potentiate aminoglycoside-induced renal enzymuria. DESIGN: Two open, randomized, double-blind, parallel-group studies were conducted in young, healthy, male volunteer subjects. Using a common protocol, 24-hour urine collections were analyzed for the renal tubular enzymes alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG), as well as for creatinine. Antimicrobial combinations studied included gentamicin plus placebo and gentamicin plus ticarcillin/clavulanate (protocol 1); and gentamicin plus placebo, gentamicin plus piperacillin, and gentamicin plus ceftazidime (protocol 2). The antimicrobial regimens were administered for 7 days. Eight subjects completed each treatment group. RESULTS: There were no significant differences between treatment groups with regard to urine creatinine excretion or serum gentamicin concentrations in either protocol. Enzymuria (AAP [p = 0.039] and NAG [p = 0.337]) was decreased in the gentamicin plus ticarcillin/clavulanate treatment compared with that in the gentamicin plus placebo treatment. Increased enzymuria, as indicated by increased urine concentrations of AAP and NAG, was observed in the gentamicin plus ceftazidime treatment (p < 0.05) compared with the other two treatments. CONCLUSIONS: Based on relative enzymuria, ticarcillin/clavulanate may be renal protective. Piperacillin neither potentiated nor ameliorated aminoglycoside-induced enzymuria. Since acute elevations in AAP and NAG reflect insults to the kidney, these studies suggest that ceftazidime may enhance aminoglycoside-induced renal injury. Piperacillin had no effect on enzymuria and would appear not to enhance or protect against aminoglycoside-induced renal injury.

A rapid sensitive monoclonal assay for lipid A in solution.

Lipid A is the toxic component of bacterial endotoxins (LPS) and LPS has been thought to be clinically important in Gram-negative bacterial sepsis, as well as in non-bacteremic states where endotoxemia of enteric origin may be deleterious. The presently accepted method of detecting both LPS and its common lipid A moiety is the Limulus lysate amebocyte assay (LAL), but this test cross-reacts with non-bacterial antigens and serum contains natural inhibitors to the reaction. As an extension of previous work using a polyclonal antibody, we have developed a rapid and sensitive monoclonal antibody assay for lipid A. This 3-step inhibition ELISA is reproducible in aqueous solutions and capable of detecting less than 10 pg/ml of this shared toxic endotoxin component. The assay does not detect intact LPS but acid hydrolysis releases the active lipid A for reaction. While already valuable in detecting lipid A in biological solutions, the presence of naturally occurring anti-lipid A immunoglobulins in serum interfere with the reaction and cause false positives in this inhibition assay. Clinical usefulness of the assay will depend on removal of these antibodies from serum prior to testing.

IgA antibody to lipid A in alcoholic liver disease.

To find out whether the increased immunoglobulin A (IgA) levels commonly reported in patients with alcoholic liver disease (ALD) are part of the immune response to gut-derived endotoxin antigen, an enzyme-linked immunoabsorbent assay was used to measure serum levels of antibodies to lipid A (the shared core of various lipopolysaccharides and the biologically active component of endotoxins) in patients with various diseases and in controls. Of 41 patients with ALD, 35 had significantly raised titres of IgA anti-lipid A. Rises of antilipid A were found in the secretory fraction of IgA as well, and titres of IgG antibody were also consistently increased. IgM titres were high in only 7 of 35 ALD patients tested. Patients with other diseases did not show significantly high titres of IgA antibodies to lipid A even though many had rises in total concentration of their serum IgA.

Antigenic heterogeneity of the non-serogroup antigen structure of Neisseria gonorrhoeae lipopolysaccharides.

Studies of the antigenic structure of the polysaccharide component of gonococcal lipopolysaccaride (LPS) indicated that the non-serogroup antigen structure is antigenically heterogeneous. Immunodiffusion studies of Gc4 strain 8551 indicated that in addition to the Gc serogroup determinent, this polysaccharide contains two other sets of determinants, one which is shared with the other five Gc serogroups and a second which is shared by the Gc1 and Gc3 serogroups. Enzyme-linked immunosorbent assay (ELISA) studies confirmed the immunodiffusion, documented qualitative differences, and suggested that quantitative differences may exist in the common determinant from serogroup to serogroup. As measured by ELISA inhibition, native LPS showed the same antigenic arrangement as the purified LPS polysaccharides. Studies with LPS-derived polysaccharides from nonprototype strains in immunodiffusion gave results identical to the prototype strains. This antigen variation, although distinct from serogroup specificity, was related to the serogroup determinant.

Degradation of the polysaccharide component of gonococcal lipopolysaccharide by gonococcal and meningococcal sonic extracts.

An extract made from the supernatant of Neisseria gonorrhoeae Gc2 strain 1291 degraded the Gc2 polysaccharide antigen. Chemical analysis of this polysaccharide indicated it contains glucose, galactose, glucosamine, galactosamine, glucosamine-6-phosphate, heptose, 2-keto-3-deoxyotonate, and ethanolamine and is the polysaccharide component of gonococcal lipopolysaccharide. Degradation of the polysaccharide by sonic extracts resulted either in complete loss of antigenicity and immunogenicity or in partial degradation to subunits that could inhibit the Gc2-specific hemagglutination inhibition. The factors responsible for degradation were destroyed by heating at 100 degrees C for 5 min or by Pronase digestion, but were unaffected by ribonuclease, deoxyribonuclease, Mg2+, Ca2+, or ethylenediaminetetraacetic acid. The process was pH dependent, with optimal activity occurring at pH 7. Sonic extract supernatants from group B and C meningococcal strains contained degrading properties, whereas similar extracts produced from Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Streptococcus pneumoniae type II failed to degrade the Gc2 polysaccharide.