Double-blind, randomized comparison of 24 weeks of norfloxacin and 12 weeks of norfloxacin followed by 12 weeks of placebo in the therapy of complicated urinary tract infection.Sheehan, G J; Harding, G K; Haase, D A; Thomson, M J; Urias, B; Kennedy, J K; Hoban, D J; Ronald, A R
doi: 10.1128/AAC.pmid: 3056259
We evaluated the benefits of prolonging norfloxacin therapy from 12 to 24 weeks for complicated urinary tract infection in a double-blind, randomized, placebo-controlled study. During the second 12 weeks, norfloxacin was superior to placebo (P less than 0.05) in suppressing bacteriuria. Adverse effects were common but mostly confined to the initial 12 weeks. Antimicrob Agents Chemother. 1988 August; 32(8): 1292-1293
Molecular cloning and genetic analysis of a chloramphenicol acetyltransferase determinant from Clostridium difficile.Wren, B W; Mullany, P; Clayton, C; Tabaqchali, S
doi: 10.1128/AAC.pmid: 2847649
A gene bank from a clinical isolate of Clostridium difficile expressing high chloramphenicol acetyltransferase activity was constructed by cloning Sau3A-cleaved clostridial DNA fragments into the plasmid vector pUC13. Among 1,020 clones tested, 11 were resistant to chloramphenicol; 1 of these, with an insert size of 1.9 kilobases (pPPM9), was studied further. The clone pPPM9 was mapped using a variety of restriction enzymes, and a 0.27-kilobase EcoRV-TaqI restriction fragment was shown to be within the chloramphenicol resistance (Cmr) gene by using transposon (Tn1000) mutagenesis. The 0.27-kilobase fragment and the 1.9-kilobase insert were radiolabeled and used as DNA probes in hybridization studies. Southern blot analysis with the gene probes against chromosomal DNA from Cmr strains of C. difficile obtained from five distinct geographical locations revealed that at least two copies of the same chloramphenicol acetyltransferase gene were present for each strain. Hybridization of the gene probes against Cmr strains of Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella edwardsii, Escherichia coli, and to four other clostridial species revealed no homology even under conditions of low stringency. Antimicrob Agents Chemother. 1988 August; 32(8): 1213-1217
Mechanism of action of DuP 721: inhibition of an early event during initiation of protein synthesis.Eustice, D C; Feldman, P A; Zajac, I; Slee, A M
doi: 10.1128/AAC.pmid: 2461163
The mode of action of DuP 721 was investigated. This compound was active primarily against gram-positive bacteria, including multiply resistant strains of staphylococci. Although inactive against wild-type Escherichia coli, DuP 721 did inhibit E. coli when the outer membrane was perturbed by genetic or chemical means. Pulse-labeling studies with E. coli PLB-3252, a membrane-defective strain, showed that DuP 721 inhibited amino acid incorporation into proteins. The 50% inhibitory concentration of DuP 721 for protein synthesis was 3.8 micrograms/ml, but it was greater than 64 micrograms/ml for RNA and DNA syntheses. The direct addition of DuP 721 to cell-free systems did not inhibit any of the reactions of protein synthesis from chain initiation through chain elongation with either synthetic or natural mRNA as template. However, cell extracts prepared from DuP 721 growth-arrested cells were defective in initiation-dependent polypeptide synthesis directed by MS2 bacteriophage RNA. These cell-free extracts were not defective in polypeptide elongation or in fMet-tRNA(fMet)-dependent polypeptide synthesis stimulated by poly(G.U). We conclude, therefore, that DuP 721 exerts its primary action at a step preceding the interaction of fMet-tRNA(fMet) and 30S ribosomal subunits with the initiator codon. Antimicrob Agents Chemother. 1988 August; 32(8): 1218-1222
Association between early inhibition of DNA synthesis and the MICs and MBCs of carboxyquinolone antimicrobial agents for wild-type and mutant gyrA nfxB(ompF) acrA Escherichia coli K-12.Chow, R T; Dougherty, T J; Fraimow, H S; Bellin, E Y; Miller, M H
doi: 10.1128/AAC.pmid: 3056251
Quinolone antimicrobial agents are known to interact with DNA gyrase, but the mechanism by which bacterial cell death occurs is not fully understood. In order to determine whether there is a correlation between quinolone-induced inhibition of early (i.e., 10 to 15 min) DNA synthesis and potency (MICs and MBCs), we measured the rate of DNA synthesis in log-phase Escherichia coli K-12 by using 3Hthymidine incorporation. Three quinolones (ciprofloxacin, norfloxacin, and difloxacin) were selected based on their decreasing activity against reference strain KL16. All three quinolones caused an early 50% inhibition of DNA synthesis which was proportional to MICs and MBCs (r greater than 0.99). Furthermore, 50% inhibition of DNA synthesis and MICs were nearly identical for mutant strains with an altered quinolone target (gyrA) or with decreased nfxB(ompF) or increased (acrA) permeability. There were significant differences (P less than 0.001) between individual quinolones in the degree of DNA synthesis inhibition in nalidixic acid-resistant gyrA and nfxB(ompF) mutant strains. The comparison of the three mutants with the wild-type strain permitted an in vivo examination of the effects of alterations of the drug target or entry on the activity determined by DNA synthesis inhibition and MICs. Antimicrob Agents Chemother. 1988 August; 32(8): 1113-1118
In vitro activity of PD 127,391, an enhanced-spectrum quinolone.Wise, R; Ashby, J P; Andrews, J M
doi: 10.1128/AAC.pmid: 3142350
The in vitro activity of PD 127,391, a dihalogenated quinolone, was compared with those of ofloxacin, ciprofloxacin, nalidixic acid, gentamicin, and cefuroxime against 525 recent isolates and well-characterized antimicrobial agent-resistant strains. The MICs of PD 127,391 against 90% of members of the family Enterobacteriaceae, Bacteroides fragilis, Haemophilus influenzae, Neisseria sp., and Streptococcus pneumoniae were less than or equal to 0.12 microgram/ml. Some 90% of Pseudomonas aeruginosa and staphylococci were susceptible to 0.25 micrograms of PD 127,391 per ml. Against most strains, PD 127,391 was 2- to 8-fold more active than ciprofloxacin, but it was 64-fold more active than ciprofloxacin against B. fragilis. Strains of members of the family Enterobacteriaceae which were resistant to nalidixic acid were less susceptible to all of the quinolones tested, including PD 127,391. The MIC and minimum lethal concentration of PD 127,391 against three strains of Chlamydia trachomatis were each 0.06 microgram/ml, and the MIC against 90% of 21 strains of Mycobacterium tuberculosis was 1 microgram/ml. PD 127,391 was less active at pH 5, its maximal activity being at pH 7 to 8. The presence of urine at pH 5.9 decreased the bactericidal activity. The protein binding of PD 127,391 was 2 to 7%, and serum had little effect on activity. Antimicrob Agents Chemother. 1988 August; 32(8): 1251-1256
New class of antifungal agents: jasplakinolide, a cyclodepsipeptide from the marine sponge, Jaspis species.Scott, V R; Boehme, R; Matthews, T R
doi: 10.1128/AAC.pmid: 3190203
Jasplakinolide is a cyclodepsipeptide which represents a new class of antifungal agents with potent activity against Candida albicans. Jasplakinolide is fungicidal against C. albicans with both a MIC and a minimum lethal concentration of 25 micrograms/ml in a broth dilution assay. This activity compares to that of the imidazole miconazole nitrate, which had a MIC of 6.2 micrograms/ml and a minimum lethal concentration of 50 micrograms/ml in the same assay. Topical administration of 2% jasplakinolide cream against a murine vaginal C. albicans infection was equivalent in efficacy to administration of miconazole nitrate at 2%. Subcutaneous administration of jasplakinolide was not effective against a systemic murine C. albicans infection. Antimicrob Agents Chemother. 1988 August; 32(8): 1154-1157
Influence of berberine sulfate on synthesis and expression of Pap fimbrial adhesin in uropathogenic Escherichia coli.Sun, D; Abraham, S N; Beachey, E H
doi: 10.1128/AAC.pmid: 2903716
We investigated the influence of berberine sulfate, an ancient Chinese antibiotic, upon the adhesion of uropathogenic Escherichia coli to erythrocytes and epithelial cells. Although berberine sulfate in increasing concentrations had no effect on bacterial growth or on the synthesis of major outer membrane proteins of the E. coli organisms, it increasingly blocked adhesion. The decreased adhesion was accompanied by a reduction in the synthesis of fimbrial subunits and in the expression of assembled fimbriae. These results suggest that the anti-infectious activity of berberine sulfate in E. coli-induced urinary tract infections may be mediated by the selective suppression of the synthesis and assembly of fimbriae by uropathogenic organisms. Antimicrob Agents Chemother. 1988 August; 32(8): 1274-1277
Monitoring beta-lactamase activity in vivo by 13C nuclear magnetic resonance spectroscopy.Mobashery, S; Lerner, S A; Johnston, M
doi: 10.1128/AAC.pmid: 3056254
A 13C-labeled cephalothin, 7 beta-(2-thienylacetamido)-3-acetoxy-13C1methyl-3-cephem-4- carboxylate (compound 1), has been prepared and used to monitor beta-lactamase activities by 13C nuclear magnetic resonance spectroscopy. Time-elapsed spectral analysis of the reaction of the labeled cephalothin with the TEM-2 beta-lactamase purified from Escherichia coli revealed the progressive loss of the cephalothin acetyl resonance at 176.8 ppm and accumulation of an acetate signal at 184.3 ppm. Spectral results identical to those observed in the in vitro experiment were obtained when compound 1 was incubated with cell suspensions of E. coli JSR-O (pBR322), which contains the plasmid-encoded TEM-2 beta-lactamase, and Enterobacter cloacae strains that contain a class I chromosomal beta-lactamase. Pseudo-first-order rate constants for the lactamase-catalyzed formation of acetate from cephalothin in vivo were obtained by integration of the 13C-acetyl resonances of compound 1 during timed incubations with cell preparations. These results constitute the first demonstration of the ability to monitor beta-lactamase activity in viable cells by nuclear magnetic resonance spectroscopy. Antimicrob Agents Chemother. 1988 August; 32(8): 1196-1203