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A number of functional studies were performed on essentially pure eosinophil preparations obtained from the ascitic fluid of a patient with eosinophilic gastroenteritis. These cells responded to chemotactic factors including a bacterial factor, partially purified C5a, and factors generated from serum or ascitic fluid. The chemotactic activity generated in the patient's ascitic fluid was capable of attracting both neutrophils and eosinophils, was dependent on the presence of complement components, and was identified as C5a. Metabolic studies demonstrated that particle ingestion by eosinophils was associated with a marked increase in hexose monophosphate shunt activity ([1-14C]glucose oxidation), H2O2 formation ([14C]formate oxidation), superoxide anion generation, chemiluminescence, thyroid hormone degradation, iodination, and estrogen binding. This postphagocytic metabolic burst by eosinophils was qualitatively similar to that observed in neutrophils, but for several parameters the eosinophil response was greater than the neutrophil response.

Fourteen strains of Escherichia coli were tested for ability to cause infective endocarditis in rabbits prepared by prior placement of an intracardiac catheter. Strains that were resistant to the bactericidal action of serum caused E. coli endocarditis in 91.4% of rabbits, whereas serum-sensitive strains usually failed to cause persisting infection (11.3% infected, P less than 0.001). Although serum-sensitive E. coli lodged on heart valves within 1 h after intravenous injection, they survived less than 24 h in most normal rabbits. In contrast to normals, all five C6-deficient rabbits injected with a serum-sensitive strain of E. coli developed infective endocarditis (P less than 0.005). No correlation was found between the presence of K1 antigen and the incidence of experimental E. coli endocarditis. Thus, the ability of strains of E. coli to establish persisting endocardial infection in rabbits appears to be directly associated with resistance to the complement-mediated serum bactericidal system. These findings may explain in part the rarity of gram-negative bacillary endocarditis in patients; they also indicate that in certain special circumstances the serum bactericidal system can play a decisive role in host defense.

Human and animal eosinophils contain a powerful neurotoxin that causes selective neuronal and axonal damage to white matter of cerebellum and spinal cord of experimental animals when injected intrathecally. This reaction is termed the "Gordon phenomenon." We purified the eosinophil-derived neurotoxin from eosinophil-rich leukocyte suspensions or eosinophil granules from four patients with various hypereosinophilic syndromes. A single protein with an average molecular weight of 18,400 was isolated by sequential chromatography on Sephadex G-50 columns and analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis of column fractions. The purified eosinophil-derived neurotoxin from the cells of these patients retained the potent neurotoxic activity of the crude eosinophil or eosinophil granule extracts in experimental animals. These animals developed the syndrome of stiffness and ataxia progressing to severe paralysis characteristic of the Gordon phenomenon. Histologic examination of the brains of animals injected with purified eosinophil-derived neurotoxin confirmed the characteristic widespread loss of Purkinje cells and severe spongiform vacuolation in the white matter of cerebellum, brain stem, and spinal cord. We have established the location of eosinophil-derived neurotoxin in the eosinophil granule and have shown that it is distinct from several other eosinophil proteins, the granule major basic protein, and the Charcot-Leyden crystal protein (lysophospholipase).

The functional abilities of macrophages from cerebrospinal fluid (CSF) have so far been little studied. We examined the acquisition of activation characteristics by CSF macrophages during the course of experimental cryptococcal meningitis. CSF macrophages developed the ability for increased reactive oxidative intermediate (H2O2) production and tumor and fungal cytotoxicity. Despite having been activated, CSF macrophages could not inhibit the growth of Cryptococcus neoformans in vitro. Immunosuppression with cyclosporine, which eliminates the natural resistance of rabbits to cryptococcal meningitis, did not prevent or diminish H2O2 production by CSF macrophages but did reduce their tumoricidal activity. Activation of CSF macrophages appears to be an integral part of the central nervous system immune response to C. neoformans in this model, but alone is insufficient to eliminate C. neoformans from the central nervous system.

This study compares the minimum inhibitory concentrations of cefoperazone, cefotaxime, and moxalactam (LY127935) for 446 aerobic gram-negative bacillary isolates and further compares the minimum inhibitory concentrations of LY127935 and these third-generation cephalosporins with those of thienamycin for Pseudomonas aeruginosa. Each antibiotic at low concentrations inhibited nearly all Enterobacteriaceae tested. Minimum inhibitory concentrations for P. aeruginosa were higher, but for a majority of strains they fell below achievable serum levels. Thienamycin and cefoperazone showed significantly greater antipseudomonal activity than did cefotaxime or LY127935. Cefoxitin-inducible resistance to LY127935 and the two cephalosporins was demonstrated among Enterobacter species but did not occur with thienamycin.

We studied the effects of cyclosporine on experimental cryptococcal meningitis. Like cortisone, cyclosporine depressed the highly effective defense mechanisms of normal rabbits against inoculated Cryptococcus neoformans, causing them to develop progressive, fatal cryptococcal meningitis. Unlike cortisone, which causes a striking reduction in leukocytes in cerebrospinal fluid, cyclosporine depressed mononuclear cell function rather than numbers. Interleukin 2, a primary target for the immunodepressive action of cyclosporine, appears to be of central importance in central nervous system defenses against cryptococci. The findings suggest that humans receiving cyclosporine are likely to suffer increased incidence of cryptococcal infection.

Naegleria fowleri meningoencephalitis is usually fatal in humans despite treatment. As a new approach, we tested intracisternal passive immune therapy in rabbits with amebic meningoencephalitis by using antinaegleria immune serum, an immunoglobulin G fraction, and a newly developed monoclonal antibody to N. fowleri. Both the immune serum and an immunoglobulin G fraction isolated from it by affinity chromatography provided a consistent, although temporary, protective effect, shown by prolongation of survival (P = 0.001). Multiple doses of immune serum further prolonged survival (P = 0.005). The protective effect of serum was retained after heating to 56 degrees C. We then developed a monoclonal antibody to N. fowleri which provided similar protection. Passive intracisternal antibody therapy might serve as an adjunctive component in the treatment of amebic meningoencephalitis.

To evaluate cotrimoxazole in the treatment of bacterial meningitis, we compared its action with that of ampicillin and chloramphenicol in experimental Haemophilus influenzae type b meningitis. Both trimethoprim and sulfamethoxazole penetrated well into the cerebrospinal fluid of infected rabbits, reaching 40 and 26%, respectively, of their simultaneous serum levels. Levels measured 30 and 60 min after intravenous injection exceeded the minimum inhibitory concentration of this combination for H. influenzae by 10- to 100-fold. The mean ratio of trimethoprim to sulfamethoxazole in cerebrospinal fluid was 1:22. Cotrimoxazole was as effective as ampicillin in therapy of beta-lactamase-negative H. influenzae meningitis and as effective as chloramphenicol for a beta-lactamase positive strain. These findings corroborate favorable preliminary clinical experience reported by others and indicate that cotrimoxazole deserves further study in the therapy of bacterial meningitis.

We studied the pharmacokinetics and in vivo antifungal action of SCH39304, a new antifungal azole compound, in rabbits. It crossed the blood-cerebrospinal fluid barrier in the presence or absence of meningeal inflammation, reaching approximately 60% of the simultaneous concentrations in serum. In the treatment of experimental cryptococcal meningitis, SCH39304 was as effective as fluconazole in reducing yeast counts in the subarachnoid space. SCH39304 and fluconazole both were highly effective against candida endophthalmitis, sterilizing the vitreous humor and the choroid and retina. SCH39304 suppressed candida endocarditis and reduced yeast counts in the kidney at all doses tested. SCH39304 was effective in the treatment of experimental cryptococcal meningitis and disseminated candidiasis. Further investigations in humans are warranted.

We studied the penetration of three azole compounds, ketoconazole, itraconazole, and fluconazole, into the ocular tissues and fluids of rabbits in the presence and absence of ocular inflammation. Drug concentrations were compared with those found in serum and cerebrospinal fluid. The rank order of penetration into eye tissue was fluconazole greater than ketoconazole greater than itraconazole. Fluconazole penetrated freely into both inflamed and uninflamed eyes. The presence of inflammation improved penetration of all three compounds into ocular fluids and tissues. Penetration of these azoles into the anterior chamber of uninflamed eyes and into the cerebrospinal fluid was similar. All three azole compounds reduced the number of yeasts found in the eye in hematogenous Candida albicans endophthalmitis in rabbits when therapy was initiated within 24 h of inoculation. However, only ketoconazole significantly reduced yeast counts in the eye when therapy was postponed for 7 days.

Itraconazole and fluconazole, two new triazoles, were examined for their antifungal activity in rabbits. Fluconazole easily crossed the blood-cerebrospinal fluid barrier, and active drug was eliminated in high concentrations in the urine. On the other hand, itraconazole did not cross the blood-cerebrospinal fluid barrier in measurable amounts, and urine concentrations were variable. Despite differences in pharmacokinetics at the site of infection, both agents were equally effective in treating cryptococcal meningitis and candida pyelonephritis in animals. By using a ketoconazole-resistant strain of Candida albicans, we showed that there was cross-resistance in vivo between these two new triazole compounds.

Amphotericin B and N-D-ornithyl amphotericin B methyl ester were compared for therapeutic efficacies against experimentally induced cryptococcal meningitis and Candida albicans endocarditis with pyelonephritis in rabbits. Antifungal activity of the two polyenes in vitro was similar for the yeasts used in these experiments. N-D-ornithyl amphotericin B methyl ester gave a slightly higher concentration in serum than amphotericin B did, but both drugs had similar elimination curves, and penetration into the cerebrospinal fluid was poor for both. Despite these similarities between the two polyenes, amphotericin B was much more effective than N-D-ornithyl amphotericin B methyl ester in the treatment of cryptococcal meningitis in rabbits. For C. albicans endocarditis, both polyenes had similar cure rates, but in vitro measurement of fungicidal activity in serum did not predict treatment outcome. For C. albicans pyelonephritis, both polyenes showed efficacy; because higher doses of the less toxic methyl ester could be used, it sterilized the urinary tract more often than amphotericin B. These studies indicate that in vivo and in vitro experiments may be needed to predict the results of treatment with polyenes.

Tolerance to penicillin exists among the viridans group of streptococci, but its therapeutic significance is unknown. We studied the effect of penicillin alone and in combination with streptomycin, in vivo and in vitro, on three strains of dextran-producing Streptococcus sanguis serotype II which possess widely various degrees of penicillin tolerance. In rabbits with experimental endocarditis, treatment with procaine penicillin (250 mg/kg intramuscularly twice daily for 5 days) decreased the number of viable organisms in valvular vegetations from 8.82 log10 +/- 0.98 CFU/g in untreated controls to 5.31 +/- 1.19 for a highly tolerant strain, 4.22 +/- 1.05 for a less tolerant strain, and 1.79 +/- 1.72 for a nontolerant strain (P less than or equal to 0.01 for comparison between any of the four groups). None of 36 rabbits infected with tolerant strains were cured by 5 days of treatment with penicillin, but 10 of 23 animals infected with the nontolerant strain were cured (P = 0.00002). When streptomycin was given in combination with penicillin, rabbits infected with the nontolerant strain were cured within 3 days, and rabbits infected with the tolerant strain were cured within 5 days. These findings indicate that tolerance can exert a critical influence on the response of S. sanguis to penicillin therapy in vivo and that the combination of penicillin plus streptomycin exerts a synergistic effect against tolerant as well as nontolerant organisms.

The minimal bactericidal concentrations of N-formimidoyl thienamycin (N-f-thienamycin) against 21 strains of enterococci isolated from patients with infective endocarditis were determined by macro- and microdilution methods. By a macrodilution technique with the minimal bactericidal concentration defined as greater than or equal to 99.9% killing of an initial inoculum, all 21 strains of enterococci were found to have minimal bactericidal concentration/minimal inhibitory concentration ratios of greater than or equal to 32. The mean minimal inhibitory concentration was 1.5 micrograms/ml (range, 0.5 to 4 micrograms/ml), and the minimal bactericidal concentration was greater than or equal to 128 micrograms/ml. The disparity between the results of our study and those published elsewhere, which reported that N-f-thienamycin is bactericidal in vitro against enterococci, may represent the relative insensitivity of the microdilution method in determining greater than or equal to 99.9% killing. The lack of in vitro bactericidal activity of N-f-thienamycin against enterococci was confirmed in vivo in the rabbit model of experimental endocarditis. N-f-Thienamycin was no more effective than penicillin alone in the treatment of experimental enterococcal endocarditis and was less effective than the combination of penicillin and gentamicin. The results indicate that N-f-thienamycin should not be used alone in the treatment of enterococcal endocarditis.

A procedure is described for the purification of basidiospores of Filobasidiella neoformans. The method involves the use of flow cytometry, and yields a suspension containing approximately 4 × 104 infective particles ml-1, of which greater than 95% are basidiospores. The application of this procedure to studies of the pathogenesis of cryptococcosis is discussed.

It has been asserted that humoral immunity is an important potentiating factor in pathogenesis of infective endocarditis, in that prior immunization to certain bacteria may predispose the host to endocarditis caused by those organisms. If so, possible future vaccination of humans with streptococcal antigens for the prevention of dental caries might increase the susceptibility of the population to streptococcal endocarditis. To examine this hypothesis further, we immunized rabbits with killed Streptococcus sanguis or Streptococcus mutans. After complement-fixing antibody had developed, the rabbits were tested for susceptibility to experimental infective endocarditis. Rabbits with high titers of complement-fixing antibody to the infecting organism developed streptococcal endocarditis less often (13%) than animals with lower titers (69%; P less than 0.0002). These findings do not support the hypothesis that pre-immunization predisposes to infective endocarditis and lend no credence to the concept that vaccination of human subjects against dental caries might increase their susceptibility to streptococcal endocarditis. On the contrary, the results of these experiments indicate that specific antibody can confer relative immunity to infective endocarditis.