A total of 393 clinical bacterial isolates were tested for their ability to agglutinate yeast cells of either Saccharomyces cerevisiae or Candida albicans. A positive agglutination of yeasts that could be prevented by methyl aD -mannoside was taken as an indication for the possible presence of a mannose-specific lectin (carbohydrate-binding protein) on the surface of the tested bacteria. Agglutination tests on glass slides showed that 38% of all the isolates tested were positive in their capacity to agglutinate yeasts. Among the various strains tested, all isolates of Serratia marcescens, Proteus morganii, and Citrobacter diversus, as well as 94% of Klebsiella pneumontae, were positive. On the other hand, only 46% of the Escherichia coli, 48% of the salmonellae, 44% of the Citrobacter freundii, and 71% of the Aeromonas hydrophila isolates were positive. A quantitative determination of the lectin activity done by observing the agglutination of yeasts in microtiter plates showed that S. marcescens isolates were the most avid binders to the yeast, whereas Klebsiella and Citrobacter isolates were the weakest.
This Gram-negative rod may cause severe meningitis in premature and newborn infants, with a very high fatality rate and serious sequelae in the surviving patients. The infection in babies usually defies all attempts at antibiotic treatment. In adults, on the other hand, the illness is a mild one, without meningitis and with rapid recovery, as shown by Olsen, Frederiksen and Siboni (1965), in a series of patients suffering from post-operative bacteriaemia. The organism possesses outstanding resistance to antimicrobial agents and shows an unusual sensitivity pattern for a Gram-negative bacterium. This report deals with the in-vitro sensitivity of 11 strains to 17 antibiotics, nalidixic acid, sulphamethoxazole and t rime thoprim. MATERIAL AND METHODS Eleven strains of Flavobacterium meningosepticum were tested for sensitivity. Six of them were King's serological type-strains A-F kindly supplied by Dr I. Sechter, Central Laboratories, Jerusalem, and five were isolates from CSF of infants with meningitis. Two belonged to serotype C and three to serotype E. All showed typical cultural and biochemical reactions (King). Minimum inhibitory concentrations (MICs) of various antibiotics and nalidixic acid were determined by the tube dilution method. The medium used was Brain Heart Infusion (pH 7-2) and the inoculum contained 5 x 105 organisms. Results were read after 18 hr at 37°C. In order to estimate minimum bactericidal concentrations, 0.1 ml from all tubes without visible growth was transferred to 10 ml Brain Heart Infusion and to tryptose agar plates for the determination of the bactericidal effect. Results were recorded after 48 hr at 37°C. MICs of sulphamethoxazole and trimethoprim, alone and in combination, were determined by the plate dilution technique, using Wellcome nutrient agar which contains insignificant amounts of end-products of folate metabolism (Bushby, 1969). The inoculum was 150-200 organisms. All strains were also tested for /3-lactamase production by iodometric assay (Perret, 1954). RESULTS All the strains were resistant to benzyl penicillin, methicillin, ampicillin, carbenicillin and cephaloridine, the MICs of which ranged from 50 to more than 100 pg per ml, and all produced penicillinase. All strains were resistant (MIC> 100 pg per ml) to dihydrostreptomycin, kanamycin, gentamicin, sulphomethyl-colistin and lincomycin (table I). MICs of tetracycline, chloramphenicol, vancomycin, pristinamycin and nalidixic acid ranged from 25 to 50 pg per ml (table I). On the other hand, the organisms were found to be sensitive to erythromycin (as lactobionate), rifampicin and novobiocin. MICs of rifampicin were from 0-6 to 1.25 pg per ml and of erythromycin from 2.5 to 10 pg per ml. Minimum bactericidal concentrations ranged from 1-25 to more than 20 pg per ml for rifampicin and from 10 to more than 20pg per ml for erythromycin (table II). Even with strains showing survival at 20 pg per ml, however, 99 per cent. of the original inoculum was killed by concentrations of 2-5-5 pg erythromycin per ml and 2.5 pg rifampi...
A model for Nocardia asteroides and Nocardia brasiliensis infections in Swiss white mice has been established without the addition to the inocula of any form of adjuvant. Serial histopathological studies revealed that these two actinomycetes cause lesions that are quite different in their features. An acute suppurative abscess characterizes the lesions of N. asteroides. In the case of N. brasiliensis infections a granuloma is produced in which a striking feature is the presence of large numbers of foam-laden macrophages, although occasional exceptions to this pattern were noted. Electron microscopic studies demonstrated that these macrophages contain within their cytoplasm organisms in varying stages of degeneration. Repeated mortality studies in mice failed to demonstrate differences in mortality rates produced by N. asteroides and N. brasiliensis. Thus, despite relatively trivial biochemical and antigenic differences between these two species of Nocardia, the local pathogenic response is quite different. The presence in the "brasiliensis lesion" of foamy macrophages with intracellular organisms is reminiscent of the histopathological features of lepromatous leprosy and of disseminated Myocobacterium bovis infection when this occurs in the immune suppressed situation. It is possible that N. brasiliensis infection produces a depression of cellular immunity that modifies the local host response to the organism.
Summary Eighteen cases of adult listeriosis (nine with meningitis, one brain abscess and eight bacteraemia) were diagnosed in the Chaim Sheba Medical Center in the years 1964–1982. The infection seemed to be opportunistic in all. Eleven patients had malignant disease, two had cirrhosis of the liver, one had ulcerative colitis, one had bronchial asthma with chronic obstructive pulmonary disease, one had pemphigus, one had diabetes mellitus and one had a renal transplantation. Twelve patients (66%) received radiation therapy and/or cytotoxic and steroid medication. Diabetes mellitus as an additional underlying disease was strikingly frequent and was found in eight out of 18 patients (44%), in one as the only underlying disease. In the meningitis group cerebrospinal fluid (CSF) cultures were positive in five patients, and negative in four who had, however, positive blood cultures. The cells in the CSF were predominantly lymphocytes in five and polymorphs in four. It may be concluded that diabetes mellitus is an important underlying disease in listeriosis. The results also reinforce the fact that lymphocytosis in the CSF does not exclude bacterial meningitis.
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