EPISOME-MEDIATED TRANSFER OF DRUG RESISTANCE IN ENTEROBACTERIACEAE. 8. SIX-DRUG-RESISTANCE R FACTOR

Watanabe, Tsutomu (Keio University School of Medicine, Tokyo, Japan), Chizuko Ogata, and Sachiko Sato. Episome-mediated transfer of drug resistance in Enterobacteriaceae. VIII. Six-drug-resistance R factor. J. Bacteriol. 88:922-928. 1964.-The multiple-drug-resistant Escherichia coli strain isolated by Lebek in 1963 was found to transfer resistance to sulfonamide, streptomycin, chloramphenicol, tetracycline, kanamycin, and neomycin together by conjugation, as well as by transduction with phage P1kc, suggesting that these drug-resistance markers are carried by a single R factor (R(6)). The results of transductional and spontaneous segregations of the drug-resistance markers of R(6) have shown that R(6) has independent genetic determinants for sulfonamide, streptomycin, chloramphenicol, tetracycline, and kanamycin-neomycin resistance. Resistance to kanamycin and neomycin is probably controlled by a single gene, because no segregation was observed between these two. The resistance transfer factor of R(6) was found to be of the fi(+) type.

RHEUMATOID FACTOR PROPERTIES OF HYPERIMMUNE RABBIT SERA

The rheumatoid factor-like substance (RFLS) induced by hyperimmunization of rabbits with bacteria was consistently and exclusively associated with the macroglobulin fraction of the sera studied. The RFLS is separable from the bulk of serum proteins by zone centrifugation, DEAE cellulose chromatography, and gel filtration. Partially purified preparations of the RFLS were studied by immunoelectrophoretic analysis and analytical ultracentrifugation. Certain RFLS sera demonstrated selective reactivity with one or more rabbit isohemagglutinin antibodies. Pepsin treatment of rabbit γ-globulin removed or greatly diminishes its capacity to react with the RFLS.

CORRELATION OF SUCCINATE METABOLISM AND VIRULENCE IN SALMONELLA TYPHIMURIUM

Herzberg, Mendel (University of Florida, Gainesville), and Mudhaffer J. Jawad, and Darrell Pratt. Succinate metabolism and virulence in Salmonella typhimurium. J. Bacteriol. 89:185-192. 1965.-A virulent, smooth strain of Salmonella typhimurium (Wild-7) grew slowly with succinate as sole carbon source (Suc-L). Old stock cultures yielded a smooth variant which grew rapidly (Suc-E). Visible colonies of Suc-E appeared in 24 hr, whereas Suc-L required 48 hr. Differences other than the response to succinate were not demonstrable between the two strains; ld(50) values of both strains were similar, but equivalent numbers of Suc-E required longer periods of time to kill mice. Recovery of bacteria from liver and spleen homogenates revealed that Suc-L remains as such in vivo, but Suc-E populations change to Suc-L. By the eighth day of infection, the organisms were 93 to 100% Suc-L; thus, mortality was due to the Suc-L population developed in vivo and not the Suc-E of the original inoculum. Animal passage of a number of stock cultures of S. typhimurium of diverse origin, all Suc-E type, invariably yielded Suc-L. Slow utilization of succinate appears to be correlated with virulence.

FLAGELLA OF SALMONELLA TYPHIMURIUM SPHEROPLASTS

Vaituzis, Z. (University of Maryland, College Park), and R. N. Doetsch. Flagella of Salmonella typhimurium spheroplasts. J. Bacteriol. 89:1586-1593. 1965.-The flagella of penicillin-induced spheroplasts of Salmonella typhimurium were examined by electron and light microscopy. The process of spheroplast formation was followed for a period of 20 hr from its inception. Flagella were found to be confined to those areas of the spheroplast where cell-wall fragments remained. Flagella disappeared as the spheroplasts aged. Spheroplasts produced from nonflagellated organisms were found incapable of synthesizing flagella. Upon inactivation of the penicillin, however, flagella again were synthesized by spheroplasts during reversion to their original rod form. Flagella formation, it is suggested, is dependent on prior synthesis of the normal cell wall. The morphology of the microorganisms at the time of appearance of new flagella is described.

BURSA OF FABRICIUS IN CHICKENS: POSSIBLE HUMORAL FACTOR

Chicks bursectomized by testosterone injection on the 5th day of incubation showed a marked inability to produce antibodies to Salmonella typhimurium. When portions of the bursa of Fabricius were enclosed in cell-impermeable Millipore diffusion chambers and implanted subcutaneously or intraperitoneally, the antibody-producing capacity of these animals was restored. Evidence strongly suggests that the bursa of Fabricius elaborates a non-cellular agent capable of restoring immunologic reactivity in bursectomized chicks.