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Biomedical subjects

E D Rosenblum

Publications and source records attributed to E D Rosenblum.

16 recordsLinked to original sources
PubMed1980

Transduction of methicillin resistance in Staphylococcus aureus: recipient effectiveness and beta-lactamase production.

The effectiveness of Staphylococcus aureus strain 8325-4 as a recipient for the transduction of methicillin resistance requires the presence of a penicillinase plasmid but was found to be independent of the lysogenic state of the recipient. Effectiveness is conferred by the plasmid in either the autonomous or integrated states, although the transduction rate is higher in the former. Once established, the maintenance and expression of methicillin resistance were independent of continued carriage of the plasmid deoxyribonucleic acid. Analysis of penicillinase plasmid mutants indicated that beta-lactamase production was the plasmid function responsible for recipient effectiveness. Supportive evidence included the abrogation of recipient effectiveness by the beta-lactamase inhibitor clavulanic acid and the elimination of a plasmid requirement with recipient strains carrying a chromosomal beta-lactamase determinant. A possible role for beta-lactamase production in the transduction of methicillin resistance is discussed.

DNA, Bacterial↗
PubMed1980

Genetic behavior of the methicillin resistance determinant in Staphylococcus aureus.

The cotransformation frequency of mecC5 with pur-102 using Staphylococcus aureus C5 deoxyribonucleic acid was found to be approximately 45%. However, in cotransduction studies, there was a 15% cotransduction of purine prototrophy and methicillin sensitivity but, in the reciprocal cross, no purine-prototrophic plus Mecr cotransductants were obtained (frequency less than 0.06%). The data support the hypothesis that the mec determinant resides on an inserted deoxyribonucleic acid sequence in S. aureus and that there is no allelic equivalent in sensitive cells.

DNA Transposable Elements↗
PubMed1978

Transduction of plasmid determinants in Staphylococcus aureus and Escherichia coli.

Buoyant density analysis of transducing lysates derived from Staphylococcus aureus and Escherichia coli indicated that phage particles bearing plasmid determinants contain a quantity of DNA equivalent to that found in the lytic particles. Transducing particles that bear plasmid determinants smaller than viral DNA must therefore contain a quantity of DNA in excess of a single plasmid genome. In the E. coli P1vir system, a dependence upon host-mediated recombination for the transduction of small plasmids, but not for large R factors or chromosomal genes, was observed. However, no evidence for the involvement of such functions in the transduction of S. aureus plasmids was obtained. Although the origin of the additional DNA in plasmid transducing particles has not been identified, circumstantial evidence has been presented in the staphylococcal system indicating that transducing particles carrying a small tetracycline plasmid are not formed by the wrapping of multiple copies of this plasmid DNA.

Chromosomes, Bacterial↗
PubMed1977

DNA replication in bacteriophage-infected Staphylococcus aureus.

The synthesis of viral and host DNA in phage-infected Staphylococcus aureus was examined. Three intracellular forms of phage 52HJD DNA were demonstrated: covalently closed circular, open circular, and linear DNA species. It was noted that infection of S. aureus-propagating strains 81 and 52 with phage 52HJD inhibited the replication of the bacterial chromosome and a stringently controlled penicillinase plasmid. A small tetracycline plasmid, normally under relaxed replication control, continued to replicate in the postinfection period. No breakdown of the host chromosome into small-molecular-weight fragments or utilization of bacterial DNA material for the synthesis of viral DNA was observed.

DNA, Bacterial↗
PubMed1973

Plasmid for tetracycline resistance in Staphylococcus epidermidis.

A plasmid determining tetracycline resistance was demonstrated for Staphylococcus epidermidis. Tetracycline resistance was spontaneously lost from a S. epidermidis strain at a frequency of <0.1 to 1.3%. Frequency of loss was not appreciably enhanced by growth at 42 C or in ethyl violet. The rate of transduction of tetracycline resistance in three S. epidermidis crosses was decreased as a function of ultraviolet irradiation of the transducing phage. Plasmid deoxyribonucleic acid (DNA) associated with tetracycline resistance was isolated by CsCl-ethidium bromide dye-buoyant density gradients. The tetracycline plasmids from S. aureus RN 1304 (molecular weight 2.66 Mdals) and S. epidermidis 367(phi367) (T(367)) cosedimented in 5 to 20% neutral and alkaline sucrose gradients and are therefore of similar molecular weights. An extrachromosomal element in the recipient strain, isolated as covalently closed circular DNA, did not retain its integrity in an alkaline sucrose gradient.

Centrifugation, Density Gradient↗
PubMed1972

Transduction of tetracycline resistance in Staphylococcus epidermidis.

Fourteen Staphylococcus epidermidis strains were biotyped according to the scheme of Baird-Parker and tested for their sensitivities to S. epidermidis typing phages. Tetracycline-susceptible strains were tested for the capacity to be transduced to resistance. Five strains, all of biotype 1, were lysed by one or more phages. Five of eight biotype 1 strains were transduced to tetracycline resistance with rates of 10(-8) to 10(-5). Three strains of other biotypes were not transduced, nor was PS 73, an unusual coagulase-negative strain. The transducing phage phi367 was isolated from the lysogenic tetracycline-resistant donor strain. The phage morphologically resembles serological group B S. aureus phages. Restriction and modification were indicated from the efficiency of plating on phage-sensitive strains.

Bacteriolysis↗
PubMed1971

Effects of the recipient strain and ultraviolet irradiation on transduction kinetics of the penicillinase plasmid of Staphylococcus aureus.

When the penicillinase plasmid of Staphylococcus aureus PS 81(P(81))(T(81)) was transferred to its cured derivative of PS 81(N(P))(T(81)), there was a fivefold increase in the transduction frequency of penicillinase plasmid markers after ultraviolet (UV) irradiation of the phage instead of the expected decrease typical for plasmid-borne markers. These results were independent of the transducing phage, the donor, and the method of curing the recipient and were also obtained with a cured derivative of PS 80(PI(80)). With PS 52, a naturally occurring penicillin-sensitive strain, and a cured transductant of PS 52 as the recipients, typical plasmid kinetics were observed. The plasmid location of penicillinase plasmid markers in transductants was confirmed by their instability in ethidium bromide (EB). In a cross between isogenic plasmids (PI(258)penZ cad x PI(258)penI asa ero), transductants were doubly selected for cadmium and erythromycin resistances. There was a twofold increase in transduction frequency after UV irradiation of the transducing phage and an increase in the proportion of recombinant type transductants. CsCl-EB density centrifugation revealed that plasmid deoxyribonucleic acid (DNA) was present in PS 81(P(81))(N(T)) and its cured derivative [PS 81(N(P))(N(T))], but not in PS 52. Sucrose gradient analysis of plasmid DNA showed that the penicillinase plasmid of PS 81(P(81))(N(T)) was larger than the plasmid in its cured derivative. Thus, the cured derivative contains plasmid DNA which appears to recombine with the incoming plasmid, causing the rise in transduction frequency noted after UV irradiation of transducing phage.

Arsenic↗
PubMed1971

Effects of ethidium bromide on growth and on loss of the penicillinase plasmid of Staphylococcus aureus.

Ethidium bromide (EB) was more efficient than ethyl violet or rifampin as a curing agent for the penicillinase plasmids of Staphylococcus aureus strains. The effects of EB on growth and on the loss of the penicillinase plasmid of PS 81 were studied in detail. The growth rates of PS 81 and an EB-cured derivative were identical in broth, but the cured derivative had a shorter lag in the presence of added 6 x 10(-6)m EB. The shortened lag was due to prior exposure to EB as the cured derivative and an EB-treated but uncured strain of PS 81 gave identical growth lag and growth rates in the presence of EB. The curing of PS 81 by EB occurs in three phases. After a 4 to 5 hr lag, there is a 100-fold increase in the number of penicillinase-negative cells, and the proportion of cured cells continues to rise until 10 to 12 hr. Thereafter, the population becomes refractory to further curing, and the proportion of penicillinase-negative cells remains constant at about 20% of the total. Penicillinase-positive survivors of EB treatment showed increased EB resistance and were cured at lower rates upon subsequent EB treatment. Isolated colonies of the parental strain PS 81 were heterogeneous in their EB sensitivity. Thus, EB does not competitively favor spontaneously cured penicillinase-negative cells but appears to act in a manner analogous to acridine orange on the plasmids of enteric bacteria.

Coloring Agents↗
PubMed1969

Transfection of lysostaphin-treated cells of Staphylococcus aureus.

After treatment with 1 unit of lysostaphin per ml for 3 min, two strains of Staphylococcus aureus, 233 and PS 44A HJD, were transfected with phenol-extracted deoxyribonucleic acid (DNA) from the staphylococcal bacteriophages, 53 and 44A HJD, respectively. The number of transfected cells was low in both systems, approximately two in 10(7) enzyme-treated cells. There was a saturation effect at high concentrations of DNA; optimal results were obtained at concentrations between 10 to 25 mug/ml. Growth curves and fluctuation tests indicated that cells of strain 44A HJD infected with phage, then converted to protoplasts by a 10-min treatment with lysostaphin, produce only one phage particle and lose their ability to lyse spontaneously in hypertonic media.

Anti-Bacterial Agents↗
PubMed1966

Biological properties of alpha-toxin mutants of Staphylococcus aureus.

McClatchy, J. K. (The University of Texas Southwestern Medical School, Dallas), and E. D. Rosenblum. Biological properties of alpha-toxin mutants of Staphylococcus aureus. J. Bacteriol. 92:575-579. 1966.-Twenty nonhemolytic mutants of Staphylococcus aureus were isolated after treatment of a hemolytic strain with ultraviolet light or nitrous acid. Thirteen strains isolated were completely lacking in the synthesis of alpha toxin or immunologically related proteins, presumably the result of a single mutational event. Although the strains were nonhemolytic on rabbit blood-agar plates, six of them retained the dermonecrotic and lethal activities usually associated with staphylococcal alpha toxin, as well as slight hemolytic activity for rabbit erythrocyte suspensions. The active mutants and one inactive mutant produced a protein that reacted immunologically with antibody to alpha toxin. Mutations which alter the alpha toxin molecule can effect the lethal, dermonecrotic, and hemolytic activities separately or in varying ratios.

Antibodies↗
PubMed1966

Genetic recombination between alpha-toxin mutants of Staphylococcus aureus.

McClatchy, J. K. (The University of Texas Southwestern Medical School, Dallas), and E. D. Rosenblum. Genetic recombination between alpha-toxin mutants of Staphylococcus aureus. J. Bacteriol. 92:580-583. 1966.-A demonstration of genetic recombination between Staphylococcus aureus nonhemolytic mutants was attempted by means of transduction. The results of two-point reciprocal transductions placed the mutants into two genetic groups. Recombination within each group was not detectable within the limits of the method, but hemolytic recombinants were obtained in transductional crosses when donor and recipient were from different groups. At least two genetic loci are therefore involved in alpha-toxin production. The 11 mutants of group II were fibrinolysin-negative. The recombinants were always found to be restored to fibrinolysin production as well as to alpha-toxin production. These data suggest the existence of a pleiotropic gene simultaneously affecting the synthesis of both alpha toxin and fibrinolysin. The nine mutants of group I were fibrinolysin-positive. Group I members are postulated to be alpha-toxin structural mutants. Three mutants were also negative for bound coagulase, but no linkage was observed between the locus controlling bound coagulase and the loci for either fibrinolysin or alpha-toxin production.

Coagulase↗
PubMed1964

Selective medium for carbohydrate-utilizing transductants of Staphylococcus aureus.

Murphey, W. H. (The University of Texas, Dallas), and E. D. Rosenblum. Selective medium for carbohydrate-utilizing transductants of Staphylococcus aureus. J. Bacteriol. 87:1198-1201. 1964.-The composition and properties of modified eosin-methylene blue agar are described. It is an efficient, selective medium for isolation of carbohydrate-utilizing staphylococci from large, nonutilizing populations. The medium has been used to measure the rate of transduction of mannitol fermentation and to demonstrate genetic recombination in mannitol-negative mutants of Staphylococcus aureus.

Carbohydrate Metabolism↗
PubMed1962

SEROLOGY AND TRANSDUCTION IN STAPHYLOCOCCAL PHAGE.

Dowell, C. E. (The University of Texas, Dallas) and E. D. Rosenblum. Serology and transduction in staphylococcal phage. J. Bacteriol. 84:1071-1075. 1962.-A triply lysogenic strain of Staphylococcus aureus was shown to carry a serological group B phage capable of transduction. Three typing phages (53, 80, 42D), either belonging to serological group B or having a close association with it, were also shown to have transducing ability. A rapid screening method was used to isolate two new transducing phages, both of which belonged to serological group B. Propagating strain 42B/47C was found to carry a transducing phage that was neutralized by both group B and group F antisera. Nine other phages belonging to serological groups other than group B did not have generalized transducing ability, nor did three group B typing phages that were atypical in their calcium requirement. It was postulated that transducing ability is associated with staphylococcal phages of serological group B and with related phages of group F.

Journal Article↗
PubMed1962

STAPHYLOCOCCAL TRANSDUCING PARTICLE.

Dowell, C. E. (The University of Texas, Dallas) and E. D. Rosenblum. Staphylococcal transducing particle. J. Bacteriol. 84:1076-1079. 1962.-When novobiocin-resistant transductants were isolated under conditions that permitted superinfection, almost all the clones were lysogenic for the transducing phage. If superinfection was prevented, then the transductants isolated were nonlysogenic, suggesting the defective nature of the transducing particle. It was noted that the transducing and plaque-forming particles showed no appreciable difference in buoyant density. No difference was found in transduction rates when either sensitive or lysogenic cells were used as recipients. Transduction rates as high as one transductant per 7 x 10(4) phage particles were obtained for novobiocin resistance.

Journal Article↗