The experimental pathogenicity in mice of strains of Proteus of animal origin

1. Strains of Proteus derived from animals produced septicaemia in mice when given in large doses intravenously, but smaller doses caused necrotic lesions in the kidneys. The organisms failed to produce kidney lesions when administered intra-peritoneally or subcutaneously but did cause septicaemia.

2. Killed suspensions of Proteus failed to induce kidney lesions.

3. Strain differences in pathogenicity were found, some strains producing naked-eye lesions in the kidney, others giving microscopic changes only in this organ; of those strains which caused no changes in the kidney tissue, some persisted for several days and others were eliminated rapidly.

4. The mechanism of this localization in the kidney is discussed.

The writer wishes to thank Dr A. Wilson Taylor and Prof. R. Lovell for their advice and helpful suggestions and Mr R. Hood for the photographs.

Occurrence of catalase in pleuropneumonia-like organisms and bacterial L forms

Weibull, C. (Central Bacteriological Laboratory of Stockholm City, Stockholm, Sweden) and Kerstin Hammarberg. Occurrence of catalase in pleuropneumonia-like organisms and bacterial L forms. J. Bacteriol. 84:520-525. 1962.-The catalase activity of six pleuropneumonia-like organisms (PPLO), four stable Proteus L forms, and four normal strains of Proteus mirabilis was determined quantitatively. The PPLO (strains of the species Mycoplasma agalactiae, hominis, laidlawii, mycoides, and strains isolated from tissue cultures) exhibited no measurable catalase activity. The L forms decomposed H(2)O(2) approximately ten times as rapidly as the normal bacteria from which they were derived.

Temperature-sensitive formic hydrogenlyase in a psychrophilic bacterium

Upadhyay, J. (Washington State University, Pullman) and J. L. Stokes. Temperature-sensitive formic hydrogenlyase in a psychrophilic bacterium. J. Bacteriol. 85:177-185. 1963.-A temperature-sensitive formic hydrogenlyase has been found in a psychrophilic bacterium, strain 82. The enzyme was most active at 30 C, but completely inactive at 45 C. In contrast, formic hydrogenlyase in mesophilic Escherichia coli was most active at 45 C, and completely inactivated only at 70 C. The hydrogenlyase-forming system in psychrophile strain 82 also was unusually heat-sensitive. It was inactivated at temperatures above 20 C; whereas, in mesophilic E. coli, Proteus vulgaris, and Salmonella oranienburg, hydrogenlyase was formed even at 45 C. This heat sensitivity of the enzyme-forming system accounted fully for the inability of strain 82 to produce gas from carbohydrates above 20 C. Psychrophile hydrogenlyase resembled the mesophilic variety in several respects. It was most active at pH 5.0. It was not formed by cells grown aerobically. It could be induced in resting-cell suspensions by use of glucose, formate, and casein hydrolysate as supplements, although several times as much glucose was required as for enzyme induction in strains of E. coli and Salmonella. The enzyme was formed best at pH 7.5, which was somewhat higher than the pH of 6 to 7 for mesophile hydrogenlyase, and by cells taken from the beginning of the stationary phase of growth.

Distribution and substrate specificity of benzylpenicillin acylase

Benzylpenicillin acylase, which hydrolyzes benzylpenicillin to 6-aminopenicillanic acid, was found to be widely distributed among members of the Schizomycetes, particularly in gram-negative bacteria, and in the genus Nocardia. The hydrolysis of a series of biosynthetic and semisynthetic penicillins by freeze-dried cells of a strain of Nocardia and of Proteus was studied. Benzylpenicillin was the preferred substrate; all departures from the benzylpenicillin side-chain structure led to reduction of substrate activity (the greater the departure, the greater the reduction in activity). Penicillin amides and methyl esters were also hydrolyzed, as were suitable N-acyl derivatives of 7-aminocephalosporanic acid. Occurrence of an enzyme activity which hydrolyzes benzylpenicillinamide to benzylpenicillin was detected in certain strains of yeasts.

NATURE OF LAC+ PROTEUS STRAINS ISOLATED FROM CLINICAL SPECIMENS

Falkow, Stanley (Walter Reed Army Institute of Research, Washington, D.C.), J. A. Wohlhieter, R. V. Citarella, and L. S. Baron. Transfer of episomic elements to Proteus. II. Nature of lac(+)Proteus strains isolated from clinical specimens. J. Bacteriol. 88:1598-1601. 1964.-Strains of Proteus mirabilis exhibiting the unusual property of utilizing lactose (lac(+)) have been reported in clinical material. A genetic examination discloses that the lac(+) determinants in these Proteus strains are associated with an infectious element, P, which is distinct from the sex factor of Escherichia coli K-12. The composite genetic element, P-lac, is readily transmissible to other enteric species and possesses properties which conform to those of an episomic element of the transfer variety. CsCl density-gradient studies of deoxyribonucleic acid (DNA) extracted from lac(+)P. mirabilis indicate that the P-lac(+) element did not arise in this species, but was acquired from an organism possessing a markedly different DNA base composition.

POLYVINYL-PYRROLIDONE-IODINE: AN ASSESSMENT OF ANTIBACTERIAL ACTIVITY

Polyvinyl-pyrrolidone-iodine complex (PVP-I) was shown to have a rapid disinfectant activityin vitroagainst vegetative bacteria and fungi and against vegetativeTrichomonas. The presence of organic matter had a slight delaying effect on the killing time. Bacterial spores survived in PVP-I for 17 hr. and fungal spores for 1½ hr. Used as an agent for pre-operative preparation of the skin, PVP-I was more efficient than others tested, rendering the skin surface sterile even when heavily contaminated, and keeping it so for 1 hr. None of the staining characteristics of iodine were noted since PVP-I was easily removed by water. Two individuals, known to be iodine sensitive, developed mild iodism after application of PVP-I.

The authors are indebted to the staff of the hospital for their co-operation; and to Berk Pharmaceuticals Limited for supplies of PVP-I, manufactured by them as Betadine (Povidone-iodine B.P.).

A NEW ENRICHMENT MEDIUM FOR SALMONELLAE

A new enrichment medium for the isolation of salmonella types from faeces is described.

The inhibitory substances for coliform organisms and enterococci in this medium are magnesium chloride and sodium hydrogen selenite.

The new medium was found in routine diagnostic work to be superior to the Mueller–Kauffmann medium in the isolation ofSalmonella typhiand only a little inferior in the isolation of other salmonella types.

When used in addition to the standard media the new medium increases the number of positive results.

I am indebted to Dr Jadranka Zajc-Satler for the identification of the salmonella types isolated and to Mrs I. Mamilovič, Miss P. Ferbežar, and Mrs D. Zavodnik for technical assistance.

ACETOLACTATE METABOLISM AND THE PRESENCE OF A DIHYDROXY ACID DEHYDRATASE IN MICRO-ORGANISMS

1. The growth characteristics of nine micro-organisms on complex broth and defined media, usually with a single nitrogen source (other than vitamins), were examined as a necessary step before growth of cells for enzyme assays. Six of these bacteria gave a positive colour test with a creatine-potassium hydroxide reagent, indicating the presence of acetoin, which other investigators have shown is formed via the intermediate, alpha-acetolactate. 2. Cell-free extracts of exponential-phase cells of Bacillus subtilis, Staphylococcus aureus, Proteus morganii, Acetobacter rancens (two strains), A. kuetzingianus, A. acetosus, Acetomonas (Acetobacter) melanogenus and Acetomonas (Acetobacter) suboxydans (A.T.C.C. no. 621) were found to contain the enzyme, dihydroxy acid dehydratase (2,3-dihydroxy acid hydro-lyase). 3. The specific activity of the dehydratase from organisms grown on valine- and isoleucine-deficient media was greater than those grown on a complex broth or media containing complete amino acid mixtures. The omission of valine plus isoleucine from a medium containing 19 amino acids caused an increase in the dehydratase specific activity of Staphylococcus aureus and Proteus morganii. 4. The rate of keto acid formation from alphabeta-dihydroxyisovalerate by extracts of six of the above-named organisms was faster than, but somewhat proportional to, the similar rate from alphabeta-dihydroxy-beta-methyl-n-valerate as substrate. 5. These findings may be related to acetolactate synthesis, acetoin formation and valine-isoleucine biosynthesis in the above-mentioned micro-organisms.

ACTIVITY OF AMPICILLIN IN VITRO COMPARED WITH OTHER ANTIBIOTICS

Comparative tests in vitro for antibacterial activity were carried out with ampicillin, tetracycline, and chloramphenicol using 673 clinical isolates of Gram-negative bacilli and Streptococcus faecalis. Further comparative tests were also carried out with ampicillin, chloramphenicol, colistin sulphate, colistin methane sulphonate, cycloserine, kanamycin, nitrofurantoin, polymyxin, streptomycin, and tetracycline, using groups of 20 strains of each of the main species selected at random from the total number of isolates. Of the total number of isolates a higher percentage was inhibited by ampicillin than by tetracycline or chloramphenicol. Ampicillin showed particularly high activity against certain species of bacteria and displayed an antibacterial spectrum not shown by any of the other antibiotics tested.

BACTERIAL NUCLEOTIDASES

Kohn, J. (Queen Mary's Hospital, London, England) and J. L. Reis. Bacterial nucleotidases. J. Bacteriol. 86:713-716. 1963.-The 3- and 5- nucleotidase activity in various bacterial species was investigated. Both enzymes were found in bacterial extracts in varying proportions. The nucleotidases were found to be very active in Proteus vulgaris, in which organism they were studied in detail. The relative activities, the pH optima, and the effect of metal ions were investigated. It was concluded that bacterial 3- and 5-nucleotidases are distinct and separate enzymes.

IN VITRO BIOLOGICAL ACTIVITY OF CEPHALOTHIN

Chang, Te-Wen (Tufts University School of Medicine, Boston, Mass.) and Louis Weinstein. In vitro biological activity of cephalothin. J. Bacteriol. 85:1022-1027. 1963.-Cephalothin is a "broad-spectrum" antibiotic active, in low concentrations, against Diplococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus. Shigella, Salmonella, and Proteus mirabilis were the most sensitive of the gram-negative organisms. Escherichia coli and Aerobacter aerogenes were suppressed to a lesser degree, whereas Pseudomonas aeruginosa and Herellea were highly resistant. Penicillin-sensitive and -resistant strains of S. aureus were equally susceptible to cephalothin. Exposure to increasing concentrations of the drug very frequently led to the development of resistance in gram-negative organisms; this was observed less often with S. aureus. Cephalothin stimulated the production of penicillinase by staphylococci, which remained sensitive to the cephalosporanic acid derivatives despite repeated subculture in increasing concentrations of the agent. Cephalothin was not inhibited by penicillinase. This antibiotic was more toxic to cultures of human amnion and mouse embryo cells than benzyl penicillin G but was less injurious than oxytetracycline, chlortetracycline, and demethylchlortetracycline; tetracylcine produced about the same degree of cellular damage as cephalothin.

CONSERVATION OF RIBOSOMAL AND MESSENGER RIBONUCLEIC ACID CISTRONS IN BACILLUS SPECIES

Doi, Roy H. (Syracuse University, Syracuse, N.Y.), and Richard T. Igarashi. Conservation of ribosomal and messenger ribonucleic acid cistrons in Bacillus species. J. Bacteriol. 90:384-390. 1965.-Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) fractions from various Bacillus species were tested for interspecies DNA-RNA hybrid formation. DNA preparations from B. subtilis, B. cereus, B. megaterium, B. stearothermophilus, and B. macerans, whose base composition varied from 33 to 50% guanylate + cytidylate content, were used in the hybrid annealing mixtures with pulse-labeled RNA from sporulating cells and from log-phase cells of B. subtilis and B. cereus. Efficient hybridization in these cases was obtained only in homologous annealing situations. When heterologous DNA and RNA preparations were tested for hybrid formation, only 1 to 6% of the homologous hybridization was obtained. Although the efficiency of hybrid formation was low, the results were reproducible. No difference in efficiency of hybrid formation was observed between the messenger RNA from sporulating cells and that from log-phase cells. When B. subtilis ribosomal RNA was placed in annealing mixtures with heterologous DNA, 47.5 to 62.9% of the homologous hybridization was obtained. These results suggest that a small number of identical sequences are present among the Bacillus species. Furthermore, the ribosomal RNA cistrons appear to be more highly conserved relative to other genetic sequences.

SURVEY OF THE BACTERIOCINES OF ENTEROCOCCI

Brock, Thomas D. (Indiana University, Bloomington), Barbara Peacher, and Deborah Pierson. A survey of the bacteriocines of enterococci. J. Bacteriol. 86:702-707. 1963.-A survey has been made of bacteriocine production by a wide variety of well-characterized strains of group D streptococci. On the basis of spectrums and sensitivity to chloroform, heat, and proteolytic enzymes, five distinct bacteriocines can be defined. Type 1 is produced by all Streptococcus zymogenes (S. faecalis var. zymogenes) strains, is active against a wide variety of gram-positive bacteria, and is also a hemolysin. Type 2 is produced by some S. liquefaciens (S. faecalis var. liquefaciens) strains, and acts on many enterococci as well as on certain other lactic acid bacteria. Type 3 is produced by certain strains of both S. faecalis and S. faecium, and inhibits a wide variety of group D streptococci, but is inactive against all other lactic acid bacteria tested except Leuconostoc citrovorum. Type 4 is produced by certain S. faecium strains and resembles in certain ways the type 3 activity, but differs from it in other ways. Type 5 has been found to be produced by only one proteolytic strain of S. zymogenes, and this bacteriocine has a very narrow spectrum. The strain that produces this bacteriocine also produces type 1 activity. No strain is sensitive to a bacteriocine of the type it produces.

SEPARATION, CHARACTERIZATION, AND BIOLOGICAL SIGNIFICANCE OF A COMMON ANTIGEN IN ENTEROBACTERIACEAE

An antigen common to Enterobacteriaceae and closely associated with endotoxin fractions has been separated by chromatography on DEAE cellulose employing elution with a NaCl gradient. The purified common antigen fails to coat erythrocytes, is poorly, if at all antigenic, it is non-dialyzable and excluded from sephadex G-100 gel. It is composed of polysaccharide and polypeptide. The most important property of this antigen thus far determined appears to be its interference with the specificity of the hemagglutination test commonly employed to measure antibody to O antigen of Enterobacteriaceae. It may also have taxonomic significance in classification of this family of bacteria.

METABOLIC PROPERTIES OF SOME L FORMS DERIVED FROM GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Weibull Claes (Central Bacteriological Laboratory of Stockholm City, Stockholm, Sweden), and Hans Gyllang. Metabolic properties of some L forms derived from gram-positive and gram-negative bacteria. J. Bacteriol. 89:1443-1447. 1965.-L forms of two gram-positive bacteria, a staphylococcus and a diphtheroid, were found to be devoid of catalase and cytochromes, whereas the normal bacteria from which these L forms were derived contained large amounts of these enzymes. On the other hand, L forms of a gram-negative bacterium, Proteus mirabilis, contained the same cytochromes as normal Proteus bacteria. (Previous investigations showed that normal cells and L forms of P. mirabilis contain approximately the same amounts of catalase.) The respiratory quotients (Q(O2)) of all L forms studied were much lower than those of the corresponding normal bacteria. The conversion of the normal organisms into L forms did not markedly affect their growth rate, measured as the time required for doubling the bacterial mass during the exponential-growth phase.

A NEW SELECTIVE BLOOD AGAR MEDIUM FOR STREPTOCOCCUS PYOGENES AND OTHER HAEMOLYTIC STREPTOCOCCI

Horse blood agar containing polymyxin B sulphate, neomycin sulphate, and fusidic acid inhibited the growth of Staph. aureus, Ps. pyocyanea, Proteus mirabilis, E. coli, and Klebsiella pneumoniae but allowed good growth of, and haemolysis by, Str. pyogenes. In a comparison with blood agar, blood 4% agar, and gentian violet blood agar, the selective medium (P.N.F.) yielded a significantly higher proportion of streptococci than the other media, both by aerobic and by anaerobic culture, from burn swab extracts deliberately contaminated with Str. pyogenes; P.N.F. culture was more effective with dilute than with heavy inocula of Str. pyogenes, allowing from three to seven times as many recoveries of Str. pyogenes from swabs contaminated with 10(-3) dilution of streptococcal cultures than cultures of the same material on the other media. Haemolytic streptococci of groups A, C, D, G, and others were isolated by aerobic culture from burns in a consecutive series of 1,277 swabs more often on P.N.F. medium than on blood 4% agar. Viable counts of 12 strains (including 11 different serological types) of Str. pyogenes showed some reduction in the numbers of colonies compared with counts on blood agar, and some strains grew more slowly on P.N.F. medium. These limitations, however, were offset and outweighed by the higher final yield of streptococci on the selective medium.

MORPHOLOGICAL CHANGES IN GRAM-NEGATIVE BACILLI EXPOSED TO CEPHALOTHIN

Chang, Te-Wen (Tufts University School of Medicine, Boston, Mass.), and Louis Weinstein. Morphological changes in gram-negative bacilli exposed to cephalothin. J. Bacteriol. 88:1790-1797. 1964.-Exposure of gram-negative bacteria to cephalothin (7-[thiophene-2-acetamido]-cephalosporanic acid) revealed the formation of long filaments and large bodies, which were capable of reverting to normal cells when removed from contact with the drug. The degree of morphological change was found to be related to the concentration of antibiotic in which the organisms were suspended. The large bodies were altered by contact with solutions of varying osmolarity. Different species showed variation in the ability to develop large bodies. A relationship between antibiotic sensitivity and the capacity to resist morphological alteration was observed. Though most sensitive gram-negative bacilli were strikingly changed by exposure to cephalothin, naturally resistant ones were unaffected. Organisms made drug-resistant in vitro underwent changes in cellular form which were qualitatively the same but less intense than those which developed in parent strains originally sensitive to cephalothin.

RAPID TECHNIQUE FOR THE ENUMERATION OF CLOSTRIDIUM PERFINGENS

A new medium, Tryptone-sulfite-neomycin (TSN) agar, and an incubation procedure for the enumeration of Clostridium perfringens are described. Tolerance to neomycin, optimal growth at 46 C, and sulfite-reducing properties of C. perfringens were used as a basis for development of the medium. Comparisons were made between sulfite-polymyxin-sulfadiazine (SPS) agar and TSN agar at 37 and 46 C with C. perfringens and other organisms. These studies indicate the quantitative and selective superiority of TSN agar, incubated at 46 C, over SPS agar.