A new plasmid-mediated β-lactamase (FPM-1) with an isoelectric point of 7.2 and a molecular weight of 26, 000 was found in a cefuroxime-resistant clinical isolate of Proteus mirabilis strain 6003. FPM-1 can be classified as a type I oxyiminocephalosporinase on the basis of its substrate specificity and inhibition pattern by clavulanic acid etc., and it conferred resistance on both the strain and transconjugants against most oxyme-type cephalosporins as well as the older ones but not against cefamycins and a few exceptional oxyme-type cephalosporins such as ceftizoxime, ceftazidime and cefixime. In a murine systemic infection model, only these FPM-1-stable drugs exhibited protective activity against the FPM-1-producing P. mirabilis 6003 similar to that against a nonproducing derivative strain. The FPM-1-mediated cefuroxime resistance in P. mirabilis 6003 was transferred to co-infected Escherichia coli 7004 at frequencies between 3.8×10^-3 and 4.0×10^-2 in a murine ascending urinary tract infection model. In the same infection model due to the FPM-1-producing E. coli transconjugant, FPM-1-stable cefixime was significantly more effective than FPM-1-labile cefteram pivoxil, although both drugs had similar therapeutic effect against its FPM-1-nonproducing counterpart strain.

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An autolysis-deficient mutant was isolated from Clostridium botulinum type A 190L by treatment with ethyl methanesulfonate. The cell wall prepared from the mutant autolyzed at much slower rate than that from the parent strain, accompanying with much less liberation of both amino terminals and reducing groups. Electron microscopic observation revealed that the mutant strain was converted to short rod or curved spherical form with thickned cell walls when the growth temperature was shifted from 37 to 45C. The mutant had a significantly larger amount of nonpeptidoglycan-carbohydrate complexes than did the parent strain and became markedly resistant to the autolysin partially purified from the parent, compared with the parent strain. Furthermore, the mutant was fairly tolerant to killing by penicillin. These results suggest that the autolysis deficiency of the mutant was due not only to the deficient production of autolysin but also to the excess accumulation of carbohydrate in the cell wall.

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Adherence to a HEp-2 cell monolayer was tested for in four strains of Salmonella derby which were isolated from patients with diarrhea. One strain, SB1, was highly adherent and another strain, SB4, was nonadherent. The other two strains exhibited moderate adherence. Further in vitro study of invasion of HEp-2 cells by S. derby and its replication in murine peritoneal macrophages was carried out using SB1 and SB4. Thin section electron micrographs revealed that SB1 invaded HEp-2 cells but SB4 did not. The number of viable bacteria within macrophages was determined at intervals after inoculation of bacteria. The result indicates that SB1 can replicate in the macrophages but SB4 cannot. Flagella and fimbriae were compared by electron microscopy between SB1 and SB4, and their lipopolysaccharides and outer membrane proteins were also compared with each other by SDS-polyacrylamide gel electrophoresis. The presence of a 41kDa protein in the outer membranes of SB1 was only the difference detected, suggesting that this protein could be a factor required for adherence of this serovar to epithelial cells.

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The antigenic formula and chemical structure of capsular polysaccharide (CPS) of Cryptococcus albidus var. albidus (C. albidus) were studied in relation to those of C. neoformans var. neoformans serotype A (C. neoformans A). The results of slide agglutination tests with factor sera and reciprocal adsorption experiments showed that antigenic formula of C. albidus was the same as that of C. neoformans A. The soluble CPSs from the two species were obtained from culture supernatants by precipitation with ethanol followed by purification by chromatography on DEAE-cellulose column. The structural analyses of such CPSs from the two species showed that the antigenic CPS fractions consisted of a backbone of α(1-3)-linked D-mannopyranosyl residues with a single branch of β(1-2)-xylose or glucuronic acid, and mostly with O-acetyl groups, in which side chains and O-acetyl groups were responsible for antigenic specificity. It was found that there was a minor difference between the CPS of C. neoformans A and that of C. albidus; in the former, unsubstituted mannose residues existed in a low frequency, but in the latter none. Moreover, the ¹H-nuclear magnetic resonance spectra of partially hydrolyzed acidic fragments of the two CPSs indicated that two xylose side chains were present between glucuronic acid side chains. Taken together, it was suggested that these two species of C. neoformans A and C. albidus are closely related to each other in their CPSs.

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The inhibitory effect of BV-araU on DNA synthesis in human embryonic lung cells infected with varicella-zoster virus (VZV) or herpes simplex virus type 1 (HSV-1) was compared with that of acyclovir. Cellular uptake of [³H]thymidine and its incorporation into DNA was markedly stimulated by the infection with VZV or HSV-1, suggesting that the incorporation was mainly due to viral DNA synthesis. DNA synthesis in VZV-infected cells was dose-dependently suppressed by BV-araU and acyclovir, although cellular uptake of [³H]thymidine decreased in cells treated with a high concentration of drugs for an extended time. DNA synthesis in HSV-1-infected cells was also markedly inhibited by both drugs in a dosedependent manner, without affecting cellular uptake of [³H]thymidine. The concentration of drugs inhibiting DNA synthesis was well correlated to their in vitro anti-VZV and anti-HSV-1 activities. The inhibitory concentration of BV-araU for DNA synthesis in VZV-infected cells was one-thousandth of that of acyclovir. Our results suggest that the antiviral action of BV-araU against VZV and HSV-1 is based on the inhibition of DNA synthesis in herpesvirus-infected cells.

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Experimental extrinsic allergic alveolitis (EAA) was induced in guinea pigs with Saccharopolyspora rectivirgula. Bronchoalveolar lavages were performed before inducing EAA (day 1, BAL 1), on day 23 (BAL 2), and on day 48 (BAL 3). The number of cells/ml in lavage fluid was increased at BAL 2 (4.79×10⁶) and BAL 3 (4.29×10⁶) compared with BAL 1 (0.56×10⁶). The number of major cell types increased simultaneously, neutrophil becoming the predominant cell type over alveolar macrophages (AM). The production of H₂O₂ by AM was measured at the different phases of EAA. Adherent AM were either non-stimulated or triggered with phorbol myristate acetate (PMA), zymosan, S. rectivirgula opsonized with normal guinea pig serum (SRNS), or S. rectivirgula opsonized with guinea pig anti-S. rectivirgula serum (SRAS). Stimulated AM produced larger quantities of H₂O₂ than unstimulated cells, PMA being the most potent stimulus. At day 1, AM stimulated with S. rectivirgula and zymosan produced similar quantities of H₂O₂. After the induction of the disease, AM stimulated with S. rectivirgula produced larger quantities of H₂O₂ than with zymosan. Production of H₂O₂ by AM stimulated with S. rectivirgula or PMA, respectively, stayed the same at day 1 and 23, but increased sharply for both stimuli at day 48. There was no difference between H₂O₂ production by AM triggered with SRNS or with SRAS. This study shows that: 1) H₂O₂ production is enhanced, especially by the offending agent, in the course of the disease; 2) the enhanced production of H₂O₂ by AM is preceded by the development of alveolitis; and, 3) the opsonization with specific antibodies does not enhance the avidity of AM for the antigen.

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Seven (6.1%) of 115 strains of Salmonella typhi isolated from Malaysian patients harbored a single large plasmid of 71 to 166mD. Two of the seven plasmidbearing strains were resistant to chloramphenicol (Cm) and tetracycline (Tc) and they transferred Cm and Tc resistance traits to Escherichia coli K12 at frequencies from 1.6×10^-7 to 1.9×10^-6. Agarose gel electrophoresis provided evidence that the resistance traits were cotransferred on a conjugative plasmid. The significance and importance of these results are discussed.

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Chemical inactivation of pathogen of Creutzfeldt-Jakob disease (CJD) was examined using the mouse-adapted CJD strain. A high concentration of formic acid, guanidine compounds, trichloroacetate and phenol prevented CJD transmission. NaOH between 0.25 and 2N lengthened the incubation periods. Sodium dodecyl sulfate (SDS) in a concentration between 1 and 3% did not alter incubation at room temperature but did completely block the transmission after boiling for 3min in 3% SDS. This method is recommended for practical disinfection.

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