The influence of radiomimetic substances on deoxyribonucleic acid synthesis and function studied in Escherichia coli phage systems - II. Properties of coliphage T 2 treated with di(2-chloroethyl)methylamine

An examination of the properties of T 2 coliphage, after treatment with the nitrogen mustard di(2-chloroethyl)methylamine, revealed a remarkable similarity to those of T 2 after X-irradiation. In particular, the phage remained capable of adsorption to the host cells and of combining with specific antibody, whilst showing a progressive loss of ability to kill the host cells with increasing dose. Further, a small degree of multiplicity and cross-reactivation was manifested, commensurate with that shown by phage X-irradiated in vitro . It is considered that these facts are consistent with the view that loss of plaque-forming ability is largely due to a failure of injection of the deoxyribonucleic acid moiety of the virus into the host cells following adsorption, an explanation already put forward by other workers in respect of X-rayed phage. This failure could arise by internal cross-linking of the DNA by the chloroethylamine, or of the DNA with the protein membrane. The experimental evidence supports the former proposal. The term 'radiomimetic' used in respect of di(2-chloroethyl)methylamine in the general title of this series is thus justifiable so far as phage inactivation is concerned.

ADANSONIAN ANALYSIS AND DEOXYRIBONUCLEIC ACID BASE COMPOSITION OF SOME GRAM-NEGATIVE BACTERIA

Colwell, R. R. (Georgetown University, Washington, D.C.), and M. Mandel. Adansonian analysis and deoxyribonucleic acid base composition of some gram-negative bacteria. J. Bacteriol. 87:1412-1422. 1964.-The deoxyribonucleic acid (DNA) base compositions and S values for a minimum of 134 coded properties were determined for representative cultures of the genera Pseudomonas, Xanthomonas, Aeromonas, Vibrio, Aerobacter, Escherichia, Alcaligenes, and Flavobacterium. Those cultures having a high degree of similarity by the criterion of numerical taxonomy were found to have similar DNA base compositions. The relative affinities of clusters of cultures suggest taxonomic relations. Eleven species of Xanthomonas might be a single species, and V. metschnikovii was shown to be more closely related to enteric bacteria than to other vibrios which, in turn, were found to be like pseudomonads. Aeromonas was found to be intermediate in similarity to enterics and pseudomonads and divisible into at least two, but possibly three, species. F. aquatile was unlike any of the other organisms studied, and its DNA also differed greatly in composition from other representatives of the genus.

THE ROLE OF INTESTINAL BACTERIA IN THE RECOVERY FROM WHOLE BODY RADIATION

Non-absorbable antibiotics, neomycin sulfate or polymyxin B, prevent death from an otherwise lethal dose of whole body radiation by suppressing the activity of the Gram-negative bacterial flora of the intestinal tract. The protective effect of such suppression has been evaluated over a range of radiation exposure from 325 to 675 r. Coliform-free animals uniformly survive exposure to 550 r, a dose which is regularly lethal for coliform bearing animals. When antibiotic treatment is begun within 1 hour after 550 r whole body radiation, survival is the rule. Delay in starting treatment is critical, for the longer the delay, the higher the mortality, even though the stool cultures meanwhile become coliform-free. When antibiotic is started prior to or immediately after radiation exposure, it must be continued for at least 3 weeks if maximum effectiveness is to be obtained. The shorter the postradiation period of treatment, the greater the mortality. This suggests that the defense systems involved require protection for at least 3 weeks in order to permit return of maximal function. The non-absorbable intestinal antibiotics are effective only when cultural data demonstrate successful elimination of the coliform flora in the gut.

VIRULENCE OF ESCHERICHIA-SHIGELLA GENETIC HYBRIDS FOR THE GUINEA PIG

Falkow, Stanley (Walter Reed Army Institute of Research, Washington, D.C.), H. Schneider, L. S. Baron, and S. B. Formal. Virulence of Escherichia-Shigella hybrids for the guinea pig. J. Bacteriol. 86:1251-1258. 1963.-Genetic recombination studies between donor Escherichia coli and recipient Shigella flexneri 2a strains were employed to examine alterations in the virulence of Shigella hybrids for guinea pigs. The genetic studies indicated that several chromosomal regions of E. coli and S. flexneri are grossly homologous. The frequency of recombination between E. coli and Shigella was decreased, however, in comparison with E. coli x E. coli matings. Moreover, the predominant Shigella hybrid classes acquired only the selected genetic marker, and extensive transfer of the Escherichia genome was detected only occasionally. The virulence studies made use of hybrids with well-defined single markers as well as those with overlapping chromosomal regions. Analysis of over one-half of the chromosome revealed only one chromosomal region, located between the rha(+) and xyl(+) genes, which was essential for virulence. However, hybrids which had received the E. coli pili antigen and fuc(+)-nic(+) determinants exhibited an intermediate virulence. Hybrids carrying a full complement of Shigella genes and the rha(+)-xyl(+)Escherichia region as a persistent exogenote (partial diploids) were of intermediate virulence. These partial diploids may return to complete virulence by elimination of the Escherichia chromosomal fragment or become avirulent by incorporation of this fragment.

TRANSFER OF DRUG RESISTANCE BETWEEN ENTERIC BACTERIA INDUCED IN THE MOUSE INTESTINE

Kasuya, Morimasa (Nagoya University School of Medicine, Nagoya, Japan). Transfer of drug resistance between enteric bacteria induced in the mouse intestine. J. Bacteriol. 88:322-328. 1964.-Transfer of multiple drug resistance in the intestines of germ-free and conventional mice was studied with strains of Shigella, Escherichia, and Klebsiella. The transfer experiment was carried out under antibiotic-free conditions to eliminate the production of drug-resistant bacteria by antibiotics. All resistance factors (chloramphenicol, streptomycin, tetracycline, and sulfathiazole) were transferred with ease in the intestinal tracts of mice, when donors and recipients multiplied freely, and acquired resistance was further transferred to other sensitive enteric bacteria in the intestinal tract. Bacteria to which resistance factors were transferred showed, in most of the experiments, exactly the same level and pattern of resistance as the donors. Based on the above, a hypothesis that the same process may possibly occur in the human intestine is presented.

MOTILE MARINE BACTERIA. I. TECHNIQUES, ECOLOGY, AND GENERAL CHARACTERISTICS

Leifson, Einar (Loyola University, Chicago, Ill.), B. J. Cosenza, R. Murchelano, and R. C. Cleverdon. Motile marine bacteria. I. Techniques, ecology, and general characteristics. J. Bacteriol. 87:652-666. 1964.-Aerobic, heterotrophic bacteria were isolated from the waters of the Long Island Sound, Narragansett Bay, Atlantic Ocean, and from the intestine of a variety of marine animals found along the shore of the Long Island Sound. A total of about 600 cultures of motile bacteria were studied morphologically and physiologically, with special emphasis on flagellar characteristics. The great majority of the bacteria isolated from the water were polar flagellate, nonfermentative, nonpigmented, and gramnegative. Most of these were straight, capsulated rods, but a considerable number were curved like vibrios. Yellow-pigmented isolates were often nonmotile, and the motile forms were most frequently subpolar flagellate. Several rosette-forming bacteria, including Caulobacter species, were isolated. Two typical spirilla and one flagellated coccus were found. Peritrichous flagellate bacteria, both gram-positive and gram-negative, were rare except in bottom mud. The normal intestinal flora of marine animals, such as fish and shellfish, consisted of polar flagellate, fermentative, non-pigmented, gram-negative, straight rods. Curved forms, like vibrios, were less common. Polar multitrichous flagellate forms were not uncommon and included all the luminescent types isolated. A considerable proportion of the polar monotrichous flagellate rods swarmed over the surface of agar media. When grown on solid media, all of these showed mixed polar and lateral flagellation; in liquid media, mainly polar flagellation was found. The ecology and general taxonomy of marine bacteria are discussed.

CLASSIFICATION OF MICROORGANISMS BY ANALYSIS OF CHEMICAL COMPOSITION. I. FEASIBILITY OF UTILIZING GAS CHROMATOGRAPHY

Abel, K. (Melpar, Inc., Falls Church, Va.), H. deSchmertzing, and J. I. Peterson. Classification of microorganisms by analysis of chemical composition. I. Feasibility of utilizing gas chromatography. J. Bacteriol. 85:1039-1044. 1963.-The feasibility of utilizing gas chromatography as a sensitive and rapid method for the analysis of lipids as a natural basis for the classification of microorganisms by chemical composition was investigated. The lipids were extracted and transesterified to component carboxylic acid methyl esters in a single step, after which the methyl esters were resolved by gas chromatography to provide distinctive chromatographic elution patterns. Similarities in the lipid carboxylic acid distribution were noted among selected species of the family Enterobacteriaceae, and significant differences were noted among selected families of the class Schizomycetes.

BACTERIA RESPONSIBLE FOR MUCILAGE-LAYER DECOMPOSITION IN KONA COFFEE CHERRIES

The predominant microbial flora present during decomposition of the mucilage layer of Kona coffee cherries were gram-negative bacteria which fermented lactose rapidly. Cultures isolated from coffee cherries under-going fermentation included species of Erwinia, Paracolobactrum, and Escherichia. Unblemished cherry surfaces and coffee plantation soil also had a microflora containing a high proportion of bacteria belonging to these three genera. Of 168 isolates tested, the 44 strains capable of demucilaging depulped coffee cherries were all members of Erwinia dissolvens. Supernatant growth medium liquids, after removal of E. dissolvens cells, actively decomposed the mucilage layer of depulped cherries.

Interleukin-6 (IL-6) and acute-phase proteins in rats with biliary sepsis

We measured serum interleukin-6 (IL-6) and acute-phase proteins, alpha 1-acid glycoprotein (AGP) and alpha 2-macroglobulin (alpha 2M), after a retrograde intrabiliary bacterial infection in rats with biliary obstruction. Maximum serum IL-6 was obtained at 6 h in rats following inoculation of bacteria (10(6) CFU/ml E. Coli) in the bile duct and it was higher than that observed in rats undergoing a bile duct ligation or a laparotomy. There was a strict relationship between the level of IL-6 at 6 h and the modified levels of AGP and alpha 2M at 48 h. AGP and alpha 2M levels were the highest in sera of rats with bile duct infection as compared with those found in sera of rats with bile duct ligation or laparotomy. After inoculation of E. Coli or E. Fecalis, blood IL-6 level was always higher at 6 h in inferior vena cava as compared with that found in the supra hepatic vein. These results indicate that IL-6 is synthesized after a biliary sepsis and that its blood level is higher in the systemic circulation than in the local circulation.

Comparison of broth and filtration methods for culturing of intravenous fluids

Ninety-six specimens of intravenous fluid solutions (D5/025 NS) were inoculated with S. aureus, E. coli, P. aeruginosa, K. pneumoniae, E. agglomerans, or C. albicans in concentrations of .1, 1, 10, or 10(2) organisms/ml. They were cultured in tubes containing 5 ml of double enriched broth and after passage through a .45 mu pore membrane filter. After 24 hours of incubation, broth cultures were 68% as sensitive as the filter cultures (p less than .001). At the lowest concentration (.1 organism/ml) broth cultures wer only 45% as sensitive as the membrane filter technique after 24 hours of growth (p less than .001). Membrane filters provide a rapid method to accurately detect and quantitate the presence of microbial contamination even at very low levels of concentration. The simplicity and accuracy of the filtration method offers the clinician a valuable adjunct in managing suspected cases of intravenous fluid related sepsis.

Citrobacter koseri. II. Serological and biochemical examination of Citrobacter koseri strains from clinical specimens

165 strains of Citrobacter koseri isolated from clinical specimens were studied and their biochemical reactions determined. They were examined serologically by means of a scheme consisting of 14 O antigens. The sources of the clinical specimens were tabulated and the epidemiological information was summarized. The clinical significance of these findings is discussed.

Massive empyema due to Citrobacter diversus

Citrobacter diversus is a gram-negative rod member of the Enterobacteriacease family. A patient is described from whom this organism was isolated twice in pure culture from empyema fluid. Our isolates of Citrobacter diversus were resistant to ampicillin and carbenicillin and sensitive to cephalothin. Citrobacter diversus should be distinguished from Citrobacter freundii, Enterobacter cloacae and Klebsiella pneumoniae. This organism joins Streptococcus pyogenes, bacteroids species, anaerobic streptococci and Escherichia coli as a cause of slight pneumonia with extensive empyema.