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1.  In Vitro Susceptibility Studies with Cefaclor and Cephalexin 
The in vitro activity of cefaclor and cephalexin against clinical isolates of four bacterial genera was compared. Both agents had a similar range of activity, but cefaclor was significantly more active by weight than cephalexin for most isolates tested.
PMCID: PMC429901  PMID: 900924
2.  Correlation of Netilmicin Agar Dilution and Disk Diffusion Susceptibilities 
A study of 283 isolates of gram-negative bacilli revealed a good correlation (r = −0.74) between disk diffusion zones of inhibition and agar dilution minimal inhibitory concentrations. Regression analysis suggested that strains with zone sizes ⋜11 mm should be considered resistant, but 34 of 45 strains resistant by minimal inhibitory concentration (including 27 strains of Pseudomonas aeruginosa) would have been called susceptible using this break point.
PMCID: PMC429900  PMID: 900923
3.  Susceptibility of Anaerobic Bacteria to Cefoxitin and Related Compounds 
Cephalothin, cefazolin, cephradine, and cefoxitin inhibited more than 75% of 326 anaerobic bacteria in vitro, but cefoxitin was the most effective against anaerobes in general and Bacteroides fragilis in particular.
PMCID: PMC352096  PMID: 879743
4.  Enhancement of Antistaphylococcal Activity of Nafcillin and Oxacillin by Sisomicin and Netilmicin 
The in vitro activity of sisomicin, netilmicin, nafcillin, and oxacillin against 35 strains of Staphylococcus aureus isolated from blood cultures of patients with endocarditis or septicemia was studied. The effects of combinations of either of the two newer aminoglycosides and either of the two penicillinase-resistant penicillins on the killing of S. aureus were investigated. All S. aureus strains were susceptible to the four antibiotics. Enhancement of antistaphylococcal activity was demonstrated by the antibiotic combinations.
PMCID: PMC429916  PMID: 907328
5.  Rapid Penicillinase Paper Strip Test for Detection of Beta-Lactamase-Producing Haemophilus influenzae and Neisseria gonorrhoeae 
A modified 1-min iodometric paper strip test for penicillinase activity was developed for detection of beta-lactamase-producing isolates of Haemophilus influenzae and Neisseria gonorrhoeae. The test is simple to perform and uses reagent-impregnated strips that may be stored for 1 year or more prior to use.
PMCID: PMC352138  PMID: 406836
6.  In Vitro Antibiotic Susceptibility of Salmonellae 
In vitro antibiotic susceptibilities were determined for 101 strains of salmonellae. Resistance to chloramphenicol and ampicillin was low. Cefamandole was active against the majority of strains and deserves further evaluation.
PMCID: PMC352132  PMID: 879753
7.  Bactericidal Activity of the Combinations of Gentamicin with Clindamycin or Chloramphenicol Against Species of Escherichia coli and Bacteroides fragilis 
The bactericidal activity of clindamycin, chloramphenicol, and gentamicin alone and of gentamicin plus clindamycin and gentamicin plus chloramphenicol was studied on 8 strains of Escherichia coli and 10 strains of Bacteroides fragilis isolated from clinical material. Gentamicin did not interfere with the activity of clindamycin or chloramphenicol against B. fragilis. The activity of gentamicin against E. coli was not influenced by clindamycin, but chloramphenicol suppressed the rapid bactericidal activity of gentamicin in seven out of eight strains of E. coli examined.
PMCID: PMC429876  PMID: 332070
8.  Ampicillin-Induced Morphological Alterations of Haemophilus influenzae Type b 
Inhibitory levels of ampicillin induced filamentation of growing Haemophilus influenzae ATCC 19418 within 30 min. Filaments became swollen and interrupted by regular periodic saccular outpouchings along the major axis. The degree of filamentation was dependent upon ampicillin concentration and time.
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PMCID: PMC352020  PMID: 301006
9.  In Vitro Activity of Netilmicin 
The activity of netilmicin against a variety of bacteria was similar to that of gentamicin, sisomicin, and tobramycin, but it was less active than these three drugs against Pseudomonas aeruginosa. Synergy with penicillin G against enterococci was demonstrated.
PMCID: PMC351980  PMID: 848942
10.  Discrepant Results of Amphotericin B Assays on Fresh Versus Frozen Serum Samples 
Amphotericin B assays on frozen serum samples (−20°C) generally underestimate the serum levels obtained on promptly processed samples. The degree of the discrepancy is variable and independent of the length of time stored.
PMCID: PMC429966  PMID: 921253
11.  Agar Shake Tube Technique for Simultaneous Determination of Aerobic and Anaerobic Susceptibility to Antibiotics† 
The broth dilution method of determining the minimum inhibitory concentration (MIC) of antibiotics has been adapted to an agar shake tube technique with semisolid media. This permits the simultaneous determination of the aerobic and anaerobic MICs for facultatively anaerobic bacteria such as staphylococci.
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PMCID: PMC429960  PMID: 335961
12.  In Vitro Activity of Rosamicin Against Neisseria and Haemophilus, Including Penicillinase-Producing Strains 
Rosamicin was significantly more active against Haemophilus and Neisseria than are many antibiotics currently used to treat or prevent infection caused by these organisms. This enhanced activity was also observed against penicillinase-producing strains.
PMCID: PMC429902  PMID: 409345
13.  Simple Method for Elimination of Aminoglycosides from Serum to Permit Bioassay of Other Antimicrobial Agents 
Cellulose phosphate powder can be added to serum to selectively bind aminoglycosides by ionic interaction without binding or inactivation of the penicillins, the cephalosporins, clindamycin, vancomycin, chloramphenicol, or trimethoprim. This simple, rapid technique permits the measurement of non-aminoglycoside antibiotics in the presence of aminoglycosides.
PMCID: PMC429899  PMID: 900922
14.  Comparative Pharmacology of Cefaclor and Cephalexin 
Two cephalosporin antibiotics, cefaclor and cephalexin, were administered orally to healthy, adult male volunteers for comparison of their pharmacological properties. In doses of 250 mg orally, cefaclor produced a peak serum concentration of 6.01 ± 0.55 (standard deviation [SD]) μg/ml compared with 9.43 ± 2.36 μg/ml for cephalexin (P < 0.01). The half-lives were 0.58 ± 0.07 (SD) h and 0.80 ± 0.12 (SD) h, and elimination constants were 1.22 ± 0.15 and 0.88 ± 0.13 h−1 for cefaclor and cephalexin, respectively (P < 0.001). Neither drug showed accumulation over the dosing period, and both were well tolerated.
PMCID: PMC429879  PMID: 900915
15.  Effect of Anaerobiosis on Antimicrobial Susceptibility of Staphylococci1 
The minimum inhibitory concentration (MIC) of 12 antibiotics was determined for four strains of staphylococci (representing the three major species) under aerobic and anaerobic conditions by using the broth dilution method. Nine of the antibiotics showed no significant difference between aerobic and anaerobic MIC for any of the four cultures. Gentamicin and kanamycin showed a small, but significant, increase in MIC for at least two strains under anaerobic conditions. Trimethoprim was less effective against all strains under anaerobic conditions.
PMCID: PMC352134  PMID: 879754
16.  Mezlocillin: In Vitro Studies of a New Broad-Spectrum Penicillin 
Mezlocillin is a new semisynthetic penicillin that inhibited 71% of the isolates of Serratia marcescens, 67% of Escherichia coli, 50% of Enterobacter spp., and 49% of Klebsiella spp. at a concentration of 12.5 μg/ml. It is also active against both indole-positive and -negative Proteus spp. and gram-positive cocci, except penicillin G-resistant Staphylococcus aureus. At a concentration of 100 μg/ml, it inhibited 94% of the isolates of Pseudomonas aeruginosa. It is more active than ampicillin, carbenicillin, and cephalothin against some gram-negative bacilli.
PMCID: PMC351920  PMID: 836016
17.  Methadone: Antimicrobial Activity and Interaction with Antibiotics 
We studied the effect of methadone, alone and in combination with antimicrobial agents, on two strains each of Staphylococcus aureus, Pseudomonas aeruginosa, and Serratia marcescens isolated from blood streams of parenteral drug abusers with bacterial endocarditis. Methadone has its own antibacterial effect, although at supraphysiological concentrations, and is even synergistic with antimicrobial agents against some organisms. Thus, methadone does not interfere with the antibacterial effects of antibiotics in vitro.
PMCID: PMC430016  PMID: 412466
18.  Antiviral Activity of Ribavirin in Rotavirus Gastroenteritis of Mice 
Ribavirin was inactive against the rotavirus of murine gastroenteritis; this may be due to the presence of guanosine inhibitors in the gut.
PMCID: PMC429963  PMID: 200170
19.  Cyclic Thymineless Death Significantly Increases Frequency of R-Plasmid Elimination 
Thymine starvation of Escherichia coli strain C600 thy (R46) eliminated the R plasmid at a frequency of 17%. This was increased fourfold, to 68%, after the same culture was subjected to an additional three cycles of growth followed by thymineless death.
PMCID: PMC429968  PMID: 335962
20.  Effect of Aminoglycosides on the Chemotactic Response of Human Polymorphonuclear Leukocytes 
Leukocyte chemotaxis was inhibited 9.6% compared with control in the presence of 10 μg of gentamicin per ml and 10.5% when exposed to 20 μg of amikacin per ml. However, cells incubated with an injectable form of gentamicin, containing preservatives, were inhibited an additional 25.8% relative to cells incubated with pure gentamicin.
PMCID: PMC429962  PMID: 921250
21.  Comparative Susceptibility of Candida albicans to Amphotericin B and Amphotericin B Methyl Ester 
The in vitro antifungal activities of amphotericin B (AMB) and amphotericin B methyl ester (AME) were compared against 465 clinical isolates of Candida albicans. AMB and AME possessed comparable activity against half of the strains, but against the remainder of the strains the activity of AME was slightly lower than that of AMB. Rarely did AME show superior antifungal activity to AMB.
PMCID: PMC429943  PMID: 335958
22.  Tolciclate: Further Antimycotic Studies 
In vitro comparison on dermatophytes showed, on a microgram-per-milliliter basis, that tolciclate was more active than clotrimazole and miconazole in inhibiting the growth of dermatophytes in Sabouraud agar with and without 10% horse serum.
PMCID: PMC429931  PMID: 907333
23.  Binding of Thienamycin and Clavulanic Acid to the Penicillin-Binding Proteins of Escherichia coli K-12 
Thienamycin and clavulanic acid are new β-lactam derivatives with structures markedly different from those of penicillins or cephalosporins. Both derivatives had the same general mode of action as typical β-lactam antibiotics since they bound to precisely the same proteins as [14C]benzylpenicillin. Thienamycin showed high affinity for penicillin-binding proteins 1, 2, 4, 5, and 6 and a lower affinity for protein 3. Protein 2 had the highest affinity for thienamycin, and concentrations from the minimal morphological change concentration (0.1 μg/ml) up to about 0.6 μg/ml resulted in the conversion of Escherichia coli KN126 into large osmotically stable round cells. Above a concentration of 0.6 μg/ml, rapid cell lysis occurred with the release of the cell contents as spheroplasts. Clavulanic acid showed good affinity for penicillin-binding protein 2, moderate affinity for proteins 1, 4, 5, and 6, and low affinity for protein 3. Protein 2 had the highest affinity for clavulanic acid, and concentrations from the minimal morphological change concentration (30 μg/ml) up to about 50 μg/ml produced a mixture of slightly elongated, swollen, bulging, and lemon-shaped cells. Above a concentration of 50 μg/ml, rapid lysis occurred with production of spheroplasts. The properties of thienamycin and clavulanic acid were compared with those of the penicillins, cephalosporins, and amidinopenicillanic acids.
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PMCID: PMC429926  PMID: 334066
24.  Comparative Stability of Cephalothin and Cefazolin in Buffer or Human Serum 
A marked loss in potency was observed when cephalothin was incubated for 5 h in human serum at 37°C. Cefazolin was stable under these conditions.
PMCID: PMC429898  PMID: 20044
25.  Synergy of Penicillin-Netilmicin Combinations Against Enterococci Including Strains Highly Resistant to Streptomycin or Kanamycin 
The in vitro activity of combinations of penicillin and netilimicin was determined against 20 clinical isolates of enterococci and compared with that obtained in simultaneous tests with penicillin/sisomicin, penicillin/streptomycin, and penicillin/kanamycin. Synergy between the two drugs in each combination was determined by the use of quantitative kill curves and was defined as a killing by the combination at least 100-fold greater than that produced by the most effective drug alone. Penicillin/netilmicin and penicillin/sisomicin combinations were found to be synergistic against the majority of isolates tested, including strains resistant to penicillin/streptomycin or penicillin/kanamycin combinations. This synergy with penicillin could be demonstrated at a concentration of ≤7 μg/ml for either netilmicin or sisomicin. Studies on the kinetics of killing produced by these combinations showed the rate and extent of killing to be directly dependent upon the organism's relative susceptibility to the aminoglycoside alone and the aminoglycoside concentration in the combination. Results also indicated that the interaction between penicillin and netilmicin was true synergy; i.e., rapid and complete killing was produced by combinations containing each drug at concentrations insufficient to produce any killing alone, and the killing observed could not be produced by either drug alone at a concentration equivalent to the total drug concentration in the combination. The potential clinical application of this synergistic interaction should be investigated further, especially in view of recent reports showing netilmicin to be considerably less toxic than gentamicin in experimental animals.
PMCID: PMC429884  PMID: 242509

Results 1-25 (366)