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1.  Practical Quantitative Assay for 5-Fluorocytosine in Serum and Other Body Fluids 
A method is described for assaying 5-fluorocytosine levels in serum or other body fluids. It is simpler and less expensive than the standard cylinder plate assay and is therefore more practical for routine diagnostic laboratory testing.
PMCID: PMC444346  PMID: 4596745
2.  Bactericidal and Sporicidal Activity of a Quaternary Ammonium Resin-Triiodide Complex 
Tests to determine the potential use of a quaternary ammonium resin-triiodide complex as a sterilizing agent showed that it was an ineffective sporicide and that bactericidal activity was impaired by complex milieu.
PMCID: PMC444331  PMID: 4670512
3.  Is There Complete Cross-Resistance of Gram-Negative Bacilli to Gentamicin and Tobramycin? 
No cross-resistance between gentamicin and tobramycin was found among 19 recent clinical isolates representing four genera of gram-negative bacilli.
PMCID: PMC444330  PMID: 4670511
4.  Comparison of Mueller-Hinton Agar and Oxoid Sensitivity Test Medium in Antibiotic Susceptibility Testing of Escherichia coli 
The in vitro activity of five antibiotics against 368 strains of Escherichia coli was determined by use of Mueller-Hinton agar and Oxoid sensitivity test medium. Minimal inhibiting concentrations were essentially identical with both media.
PMCID: PMC444329  PMID: 4597117
5.  Comparison of Cefazolin, a New Cephalosporin Antibiotic, with Cephalothin 
Resistance to cephalothin was associated in general with a lack of susceptibility to cefazolin, a new 7-amino cephalosporanic acid derivative.
PMCID: PMC444314  PMID: 4670505
6.  Disposable Plastic Tray for Large Plate Assays of Antibiotics 
A new disposable plastic tray for large plate assays of antibiotics was compared with conventional trays with plate-glass bottoms, and was found to be entirely satisfactory.
PMCID: PMC444265  PMID: 4670658
8.  Effect of Elevated Atmospheric Pressure on Antibiotic Susceptibility of Staphylococcus aureus and Streptococcus pyogenes 
Staphylococcus aureus showed decreased susceptibility to penicillin, vancomycin, sodium cephalothin, and tetracycline, but increased susceptibility to sodium colistimethate, at a pressure of 68 atm in helium or helium-oxygen gas. Susceptibility of Streptococcus pyogenes was unchanged by pressurization.
PMCID: PMC444252  PMID: 4618457
9.  Cross-Resistance of Pseudomonas to Gentamicin and Tobramycin 
Clinical isolates of gentamicin-resistant organisms were found to be resistant to tobramycin, a new aminoglycoside antibiotic.
PMCID: PMC444207  PMID: 4625628
10.  Effect of Cytosine Arabinoside, Adenine Arabinoside, Tilorone, and Rifamycin SV on Multiplication of Herpesvirus saimiri In Vitro 
The multiplication of Herpesvirus saimiri was inhibited in vitro by cytosine arabinoside, adenine arabinoside, and tilorone, but not by rifamycin SV.
PMCID: PMC444171  PMID: 4670435
11.  Effect of Interferon Inducers and Interferon on Bacterial Infections 
The effect of interferon inducers and exogenous L-cell interferon on the infection of mice by Pasteurella tularensis or Diplococcus pneumoniae was investigated. The results indicate that the degree of protection is dependent on the type of inducer used. A variety of defense mechanisms with limited nonspecific activity appear to be involved.
PMCID: PMC444170  PMID: 4670434
12.  Tilorone Hydrochloride: Lack of Correlation Between Interferon Induction and Viral Protection 
The protection of mice against MM virus infection and the induction of circulating interferon by tilorone hydrochloride were determined. Whereas protection was evident with doses of 0.15 and 1.5 mg/kg, interferon was not detected with doses lower than 150 mg/kg. Protection was apparently not dependent on interferon induction.
PMCID: PMC444169  PMID: 4670433
13.  7-Chlorolincomycin Therapy of Pulmonary Infections Due to Mycoplasma pneumoniae 
Nine ill patients with serologically proved pulmonary infection due to Mycoplasma pneumoniae were treated with 7-chlorolincomycin. The symptomatic responses with 900 to 1,200-mg doses were dramatic.
PMCID: PMC444345  PMID: 4596744
14.  Relationship of Chemical Structure and Antimicrobial Activity of Alkyl Amides and Amines 
Contrary to the limited effects of alkyl amides and their corresponding N-derivatives, alkyl amines affected both gram-positive and gram-negative organisms. As with other alkyl derivatives the most sensitive gram-negative bacteria were usually more resistant than the most resistant gram-positive bacteria.
Compounds with a chain-length of 11 to 15 are most active. Although some of the general properties relating the activity of fatty acids to their antimicrobial action are similar to those of amine compounds, the amines are unique in that monounsaturation does not increase compound activity.
The possible modes of action of these compounds are discussed.
PMCID: PMC444344  PMID: 4670442
15.  Clinical Significance of In Vitro Synergism Between Antibiotics in Gram-Negative Infections 
Five combinations of antibiotics (ampicillin/gentamicin, cephalothin/gentamicin, carbenicillin/gentamicin, polymyxin/carbenicillin, and carbenicillin/cephalothin) were investigated in vitro and in 148 severe infectious episodes caused by gram-negative bacilli in patients with disseminated cancer. The use of combinations that were synergistic in vitro against the offending microorganism (synergy was defined as occurring when the minimal inhibitory concentration of each of the drugs in the combination was one-quarter or less of the minimal inhibitory concentration of each drug alone) was associated with a significantly better response to antibacterial therapy (P < 0.01) than the use of combinations that were not synergistic against the causative agent.
PMCID: PMC444341  PMID: 4596743
16.  Mode of Action of a Staphylococcus epidermidis Bacteriocin 
Staphylococcin 1580, a bacteriocin produced by Staphylococcus epidermidis 1580, is bactericidal to sensitive cells of many gram-positive bacteria and stable staphylococcal L-forms. The bacteriocin inhibited simultaneously the syntheses of deoxyribonucleic acid, ribonucleic acid, and protein, and caused neither degradation of deoxyribonucleic acid nor induction of phages in lysogenic, sensitive cells. After 1 hr of treatment, extensive degradation of ribonucleic acid occurred, which was accompanied by leakage of ultraviolet-absorbing material out of the cell. The incorporation of glucose in acid-precipitable and glycogenlike material was inhibited. Furthermore, the staphylococcin inhibited the transport of glucose, glutamic acid, rubidium ions, and o-nitrophenyl-β-galactoside. The uptake of oxygen was only gradually affected, but the intracellular adenosine triphosphate level fell rapidly to 15% of the control value. The motility of sensitive Bacillus subtilis cells was markedly reduced on treatment. Staphylococcin 1580 exhibited no phospholipase activity. The phenomena are interpreted as resulting from an altered conformation and composition of the membrane, from an inhibition of transport through the membrane, or from a combination of these effects.
PMCID: PMC444339  PMID: 4274969
17.  Catabolite Repression in Inhibition of β-Galactosidase Synthesis by Escherichia coli in the Presence of Agents Producing Translation Errors 
Studies were made of the synthesis of β-galactosidase by Escherichia coli in the presence of 5-fluorouracil, streptomycin, and subinhibitory concentrations of chloramphenicol. The preferential inhibition of β-galactosidase synthesis observed in the presence of the above drugs was found to be caused by catabolite repression.
PMCID: PMC444338  PMID: 4596742
18.  Inhibition of β-Lactamases by β-Lactam Antibiotics 
The inhibitory properties of a selected number of β-lactam antibiotics were studied, with the use of three distinct types of β-lactamases. The three enzymes were found to be distinguishable on the basis of their susceptibility to inhibition. Not one of the potential inhibitors tested was found to be a potent inhibitor of all three enzymes, but nafcillin possessed the broadest inhibitory activity. The enzyme isolated from Enterobacter cloacae was found to be the most susceptible. In some cases, the degree of inhibition varied with the time of incubation, and, depending upon the time chosen, widely different observations could be made. It is suggested that, in studies such as these, every consideration should be given to the period of incubation and to the concentration of inhibitor employed. Mixtures of inhibitor and cephaloridine did not always act synergistically against growing bacteria, and a number of reasons for failure are suggested.
PMCID: PMC444337  PMID: 4670438
19.  Relationship Between the Uptake of Isoniazid and Its Action on In Vivo Mycolic Acid Synthesis in Mycobacterium tuberculosis 
A direct relationship was established between the rate of uptake of isoniazid and the action of this drug on in vivo mycolic acid synthesis in Mycobacterium tuberculosis H37Ra. The rate of uptake of isoniazid increased linearly with its external concentration and appeared to reach a maximal value of 52 pmoles per hr per 109 cells at an external concentration of about 13 μm. Correspondingly, the rate of inhibition of mycolic acid synthesis increased with the rise in the rate of uptake of the drug. A 50% inhibition of mycolic acid synthesis occurred when the uptake of isoniazid reached 5.2 pmoles per 109 cells. Calculations showed that this level of drug uptake represents an internal cellular concentration of 9 μm. These results show clearly that the action of isoniazid on the mycolate synthetase system of M. tuberculosis is rapid and that this enzyme system is highly sensitive to the drug.
PMCID: PMC444336  PMID: 4207759
20.  Comparative Activity of Sisomicin, Gentamicin, Kanamycin, and Tobramycin 
Gentamicin, sisomicin, tobramycin, and kanamycin were compared in parallel tests in vitro and in vivo against a variety of bacterial strains and species. A number of differences were seen in vitro, in particular: (i) the lower activity of kanamycin, (ii) the greater activity of tobramycin against Pseudomonas, (iii) the greater activity of gentamicin and sisomicin against Serratia, and (iv) the generally similar results with tobramycin, gentamicin, and sisomicin against species other than Pseudomonas and Serratia, with the ranking in order of decreasing activity being sisomicin, gentamicin, and tobramycin. Analysis of disc test results suggested that the gentamicin disc is not adequate for testing the susceptibility of all bacteria to sisomicin or tobramycin. In vivo tests did not confirm all specifics of in vitro tests; results of in vivo tests indicated that sisomicin may be the most active. It is suggested that the place of each of the antibiotics in human therapy can best be evaluated by more rigorous in vivo tests and clinical studies rather than extensive in vitro comparisons.
PMCID: PMC444335  PMID: 4670437
21.  In Vitro Antibacterial Activity of Spectinomycin 
The in vitro inhibitory and bactericidal activities of spectinomycin hydrochloride were tested against a variety of bacteria. The antibiotic was inhibitory at 31.2 μg/ml to most strains of Escherichia coli, Klebsiella, Enterobacter, and Staphylococcus epidermidis. Concentrations of antibiotic exhibiting bactericidal activity exceeded the inhibitory concentration by at least fourfold. Regression graphs were plotted for results obtained with 30-, 100-, 200-, and 300-μg spectinomycin discs; tentative interpretative standards are proposed.
PMCID: PMC444334  PMID: 4274968
22.  Clotrimazole (Bay b 5097): In Vitro and Clinical Pharmacological Studies 
Clotrimazole (Bay b 5097) is a new synthetic antifungal drug with in vitro activity against Candida spp., Torulopsis glabrata, and Saccharomyces spp. Pharmacological studies in man after the oral administration of 1.5 and 3 g of clotrimazole produced mean peak concentrations in the serum of 1.16 and 1.29 μg/ml, respectively, 2 hr after administration. In six patients taking 1.5 g of clotrimazole every 6 hr, there was a progressive decline in the serum concentrations after administration of a dose on days 1, 4, and 8. Nine other patients begun on a similar schedule manifested gastrointestinal symptoms attributed to the clotrimazole and were unable to complete the study. Concentrations of active drug in the urine were less than 1% of the administered dose.
PMCID: PMC444333  PMID: 4677595
23.  Quality Control of Antimicrobial Disc Susceptibility Testing with a Rapid Method Compared to the Standard Methods 
A rapid method for assay of antimicrobial agents in human serum was modified to provide a method for rapidly assessing the activity of antimicrobial discs being used for susceptibility testing. Each morning, discs are taken from the clinical laboratory's working supply and are applied directly onto test plates which have been inoculated, preincubated, and stored in a refrigerator. Inhibitory zones can be measured within 5 to 6 hr, i.e., before that day's batch of tests is to be set up. If the zone of inhibition for any agent is more than 2 standard deviations below the mean, the discs are discarded and another cartridge is selected from the stock supply for that day's susceptibility tests. In this way, discs of questionable potency are discarded before they are used for testing, rather than waiting until the next day as is usually done with the standard methods. The rapid control test yields zones which are slightly smaller and somewhat more variable than with the standard Kirby-Bauer or agar overlay methods, but the slight decrease in precision is outweighed by the advantages of rapidity and simplicity.
PMCID: PMC444332  PMID: 4670436
24.  Antimicrobial Activity of a Series of Halo-Nitro Compounds 
Sec-α-halo-nitro compounds are active antibacterial and antifungal agents, and the sec-bromo derivatives are the most active and stable.
PMCID: PMC444347  PMID: 4670443
25.  Inhibition of Peptidoglycan Synthesis by the Antibiotic Diumycin A 
Diumycin A, a new antibiotic, was found to inhibit cell wall synthesis by Staphylococcus aureus, a phenomenon accompanied by accumulation of uridine-5′-diphosphate-N-acetyl-muramyl-pentapeptide. The antibiotic inhibited in vitro peptidoglycan synthesis by particulate preparations of Bacillus stearothermophilus and Escherichia coli by preventing the utilization of N-acetyl-glucosamine-N-acetyl-muramyl-pentapeptide. In contrast to vancomycin, the antibiotics diumycin, prasinomycin, moenomycin, 11.837 RP, and enduracidin do not inhibit particulate d-alanine carboxypeptidase.
PMCID: PMC444343  PMID: 4670441

Results 1-25 (185)