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The complete nucleotide sequences of the Mycobacterium leprae23 S and 5 S rRNA genes and their flanking regions are presented. As compared to other eubacterial homologous molecules the 23 S rDNA exhibits two insertions. A 16 nucleotide long insertion is almost unique to members of the genus Mycobacterium, while the second represents an extended version of helix 54. The potential or both insertions to serve as target for diagnostic oligonucleotide probes was proven by comparative sequence analysis of 23 S rRNA or several Mycobacteriumspecies and by dot blot hybridization. In addition, a 19-mer oligonucleotide probe is described, which can be considered genus Mycobacterium-specific.

Mycobacterium lepraemurium infection of mice produces a chronic lethal disease that is characterized by massive accumulation of macrophages throughout the mononuclear-phagocyte system. We studied the influence of M. lepraemurium infection on the composition and function of the hematopoietic system. Medullary erythropoiesis was virtually abolished, as reflected by a small number of erythroid elements and a decrease in the number and frequency of erythroid progenitors in the bone marrow, together with reduced uptake of 59Fe into bone marrow hemin. On the other hand, erythropoiesis was observed in the spleen, as demonstrated by a large number of erythroid cells, a sixfold increase of 59Fe uptake, and a pronounced increase in the number of erythroid progenitors. A considerable increase of monocyte progenitors was observed in the spleen, and a more modest increase was observed in the bone marrow. This increase may be accounted for, at least in part, by greatly increased levels of macrophage-colony-stimulating factor in the serum of infected mice. Thus, M. lepraemurium infection produces important changes in the hematopoietic system, during the course of which the spleen becomes the major hematopoietic organ.

In this report we attempt to explain the discrepancy between beta-glucosidase (EC 3.2.1.21) activity in Candida albicans as measured by commercial kits and that found in an experimental assay. beta-Glucosidase activity in American and Israeli isolates of C. albicans was evaluated with the API ZYM and YeastIdent systems (Analytab Products) and with experimental biochemical assays. Activity was found with whole cells and cell extracts of isolates from both sources. The greatest beta-glucosidase activity was found at pH 5.0 and with p-nitrophenyl-beta-glucopyranoside (PNP-BDG) as the substrate. In assays with beta-naphthyl-beta-D-glucopyranoside and 6-bromo-2-naphthyl-beta-D-glucopyranoside (6-Br-2-naphthyl-BDG), no enzyme activity was detected in whole cells and only limited activity was found in cell extracts of isolates from both sources. In studies with PNP-BDG at pH 5.0 and 7.5, 29 to 38% less activity was found at both pHs with American whole cells, and minor activity (20%) was found at pH 7.5 with isolates from both sources. Because assays with PNP-BDG in cell extracts of isolates from both sources showed no significant differences in activity, the more limited beta-glucosidase activity in American whole cells was most likely due to less efficient transport. Because the API ZYM system uses 6-Br-2-naphthyl-BDG as the substrate and because the substrate is buffered at pH 7.5 in the API YeastIdent kit, both systems appear to be of limited value for the detection of beta-glucosidase activity in C. albicans.

The conservation and duplication of the tuf gene encoding the elongation factor EF-Tu were used to define phylogenetic relationships among eubacteria. When the tufA gene of Escherichia coli was used as a probe in hybridization experiments, duplicate tuf genes were found in gram-negative bacteria from three major phyla: purple bacteria, bacteroides, and cyanobacteria. Only a single copy of tuf was found in gram-positive bacteria, including mycobacteria and mycoplasmas. Gram-positive clostridia were found to carry two copies of tuf.

The number of rRNA genes of Mycobacterium leprae was determined by restriction analysis of M. leprae total chromosomal DNA. A single set of rRNA genes was found. This set was subcloned from a cosmid library of M. leprae DNA into pUC13 and was characterized by restriction analysis and hybridization with Escherichia coli rRNA genes. The 16S, 23S, and 5S genes of M. leprae were clustered on a 5.3-kilobase DNA fragment. On one hand, restriction analysis of the set of rRNA genes showed the uniqueness of M. leprae among mycobacteria, but on the other hand, it suggested that M. leprae strains of several origins are very much alike. Quantitative hybridization studies between M. leprae rDNA and total DNA of various bacteria demonstrated a close relatedness between M. leprae and corynebacteria, nocardia, and mycobacteria, especially Mycobacterium tuberculosis.

ABSTRACTIn a retrospective 10-year analysis of 3,536 patient-unique isolates, Acinetobacter baumanniiimipenem susceptibility declined from 98.1 (1990) to 64.1% (2000), and ciprofloxacin susceptibility decreased from 50.5 to 13.1%. Imipenem median zone diameters decreased from 27.7 (1997) to 18.8 mm (2000). No outbreaks were detected. Two clusters were identified for 41 strains genotyped by pulsed-field gel electrophoresis, but imipenem resistance was not clonal.