bluuebunny/crossref_metadata_2025 huggingface dataset:
Gentamicin concentrations in human subcutaneous tissue
Authors: Lorentzen H , Kallehave F , Kolmos H J , Knigge U , Bülow J , Gottrup F
Published: October 2018

Wound infections frequently originate from the subcutaneous tissue. The effect of gentamicin in subcutaneous tissue has, however, normally been evaluated from concentrations in blood or wound fluid. The aim of the present study was to investigate the pharmacokinetic properties of gentamicin in human subcutaneous adipose tissue by a microdialysis technique. Seven healthy young volunteers each had four microdialysis probes placed in the fat (subcutaneous) layer of the abdominal skin. After the administration of a 240-mg gentamicin intravenous bolus, consecutive measurements of the drug concentrations in serum and subcutaneous interstitial fluid were obtained simultaneously for 6 h. The tissue gentamicin concentration peaked after 10 to 30 min. The peak concentration in the tissue was 6.7 +/- 2.0 mg.liter-1 (standard deviation), equivalent to 39.1% of the peak concentration in serum. The area under the concentration-versus-time curve for the first 6 h in the tissue was 1,281 +/- 390.0) mg.min liter-1, equivalent to 59.7% of the area under the concentration-versus-time curve in serum. It is concluded that the microdialysis technique can be used to make dynamic and quantitative measurements of the gentamicin concentration in human subcutaneous tissue. In this adipose tissue, the peak concentrations of gentamicin were approximately seven times the MIC for Pseudomonas aeruginosa and 33 times the MIC for Staphylococcus aureus after the administration of an intravenous bolus of 240 mg, indicating the presence of sufficient concentrations in the adipose tissue to be effective against common bacteria.
Evaluation of renal toxicity and antifungal activity of free and liposomal amphotericin B following a single intravenous dose to diabetic rats with systemic candidiasis
Authors: Wasan K M , Conklin J S
Published: October 2018

Since fungal infections are prevalent in diabetic patients, in whom treatment is often complicated by underlying renal disease and dyslipidemias, the purpose of the present study was to determine if the antifungal activity and nephrotoxic effects of amphotericin B (AmB) and liposomal AmB (L-AmB) are different in nondiabetic (normolipidemic) rats compared with those in diabetic (dyslipidemic) rats with systemic candidiasis. Non diabetic and diabetic rats infected with Candida albicans received a single intravenous dose of either AmB (0.8 mg of AmB per kg of body weight), L-AmB (0.8, 2, or 4 mg of AmB per kg), or an equivalent volume of normal saline (1 ml). Renal function was assessed by insulin clearance, and antifungal activity was determined by measuring the numbers of CFU of C. albicans that were present in the right kidney following drug treatment. AmB at 0.8 mg/kg and L-AmB at 0.8, 2, and 4 mg/kg are effective antifungal agents in both diabetic and nondiabetic rats. However, while there was approximately a 4-fold decline in the mean number of CFU per gram of kidney in nondiabetic rats, there was only approximately a 2.5-fold decline for the comparable dose (AmB, 0.8 mg/kg) in diabetic rats. There also appeared to be a similar fold reduction of L-AmB at all of the dosages tested. AmB treatment significantly improved renal function in diabetic and nondiabetic rats with systemic candidiasis. Although L-AmB at all doses tested significantly improved renal function in diabetic rats with systemic candidiasis, only L-AmB at doses of 2 and 4 mg/kg significantly improved renal function in nondiabetic rats with systemic candidiasis. These findings suggest that following administration of a single intravenous dose, AmB and L-AmB appear to be less effective in killing C. albicans isolates in diabetic than in nondiabetic rats, while they were found to improve the renal functions of rats in both treatment groups.
Penetration of cefpodoxime into uterine and vaginal secretions from postpartum women after a single oral dose of cefpodoxime proxetil
Authors: Takasugi N , Tsunaga N , Sugino N , Numa F , Kato H
Published: October 2018

We evaluated the usefulness of cefpodoxime proxetil (CPDX-PR) in the treatment of puerperal infection and obtained the following results. (i) The susceptibilities of 124 clinical isolates from 85 uterine lochia samples were determined. The MIC at which the growth of Streptococcus agalactiae, Escherichia coli, and Bacteroides fragilis isolates was inhibited by 90% (MIC90) was 0.39 micrograms/ml or less. The MIC90 for Staphylococcus aureus was 3.13 micrograms/ml. (ii) Seven puerperal women received 200 mg of CPDX-PR orally. The CPDX concentration in the lochias in the uterine cavity was not statistically different from that in the vagina, suggesting that the vaginal samples, which can be obtained more safely and aseptically, can be substituted for the uterine samples. The CPDX concentration in cubital venous blood reached a peak of 1.61 micrograms/ml at 3 hours after CPDX-PR administration. The CPDX concentration in the lochias gradually increased and reached a peak of 1.20 micrograms/ml in the uterine cavity and 1.27 micrograms/ml in the vagina at 5 h after drug administration and gradually declined thereafter. These results suggest that CPDX-PR, with its good transfer to the lochia and its potent antimicrobial activity, is a promising drug for the prophylactic and therapeutic treatment of puerperal infections caused by susceptible organisms.
Comparative characterization of the cephamycinase blaCMY-1 gene and its relationship with other beta-lactamase genes
Authors: Bauernfeind A , Stemplinger I , Jungwirth R , Wilhelm R , Chong Y
Published: October 2018

A plasmidic beta-lactamase which hydrolyzed cephamycins was first detected and reported in 1989. At that time its description was restricted to phenotypic characteristics. We analyzed nucleotide sequence of its gene and explored it genetic relationship with other bla genes. The deduced amino acid sequence of the blaCMY-1 product was compared with those of other known plasmidic cephamycinases and of chromosomal AmpC beta-lactamases. The results indicate that the relationship of CMY-1 is closest to MOX-1 among the plasmidic cephamycinases and to AmpC of Pseudomonas aeruginosa among the chromosomal cephalosporinases. We conclude that the plasmidic cephamycinases described up to now may be classified into three families, as follows: CMY-1, MOX-1, and FOX-1 with AmpC of P. aeruginosa; CMY-2, BIL-1 and LAT-1 with AmpC of Citrobacter freundii; and MIR-1 with AmpC of Enterobacter cloacae. Plasmidic cephamycinases are now recognized as clinically relevant class C beta-lactamases.
Sequence analysis, purification, and study of inhibition by 4-quinolones of the DNA gyrase from Mycobacterium smegmatis
Authors: Revel-Viravau V , Truong Q C , Moreau N , Jarlier V , Sougakoff W
Published: October 2018

We determined the nucleotide sequence of a 6-kb DNA region harboring the recF, orf192, gyrB, and gyrA genes from Mycobacterium smegmatis mc(2)155. The amino acid sequences deduced from gyrA and gyrB displayed 89 and 86% identity, respectively, with the DNA gyrase from Mycobacterium tuberculosis, and 67 and 65% identity, respectively, with that from Streptomyces coelicolor. An open reading frame encoding the C-terminal region of the M. smegmatis RecF polypeptide was found upstream from gyrB and was 57% identical to the open reading frame encoding the C-terminal region of the S. coelicolor RecF protein. The gene orf192 was identified between recF and gyrB and was 39% identical to orf191 found in S. coelicolor in the recF-gyrB region. The M. smegmatis DNA gyrase, which was purified by affinity chromatography on novobiocin-Sepharose, consisted of two polypeptides with apparent molecular masses of 98 and 80 kDa. Determination of the N-terminal amino acid sequence of the B subunit confirmed GTG as the start codon in gyrB. Analysis of the supercoiling activity of the enzyme indicated that the M. smegmatis DNA gyrase was characterized by a specific activity equivalent to that of the Escherichia coli DNA gyrase. Inhibition of this activity by 4-quinolones was investigated by determining the 50% inhibitory concentrations (IC50S) of nalidixic acid, ofloxacin, and ciprofloxacin. The results indicated that the inhibitory activities of these drugs against the M. smegmatis DNA gyrase were markedly lower than those previously reported for the E. coli DNA gyrase. The results also suggested that the higher levels of activity of ofloxacin and ciprofloxacin against M. smegmatis (MICs, 0.5 to 1 microgram/ml), in contrast to that of nalidixic acid (MIC, 256 micrograms/ml), could be related to the higher inhibitory activities of fluoroquinolones against the DNA gyrase from this species (IC50S, 7 to 14 micrograms/ml) compared with that of nalidixic acid (IC50, 1,400 micrograms/ml).
MIC and time-kill study of antipneumococcal activities of RPR 106972 (a new oral streptogramin), RP 59500 (quinupristin-dalfopristin), pyostacine (RP 7293), penicillin G, cefotaxime, erythromycin, and clarithromycin against 10 penicillin-susceptible and -resistant pneumococci
Authors: Pankuch G A , Jacobs M R , Appelbaum P C
Published: October 2018

Broth MICs and time-kill studies were used to test the activity of RP 59500 (quinupristin-dalfopristin), RPR 106972, pyostacine (RP 7293), erythromycin, clarithromycin, and cefotaxime for four penicillin-susceptible (MICs of 0.008 to 0.03 microgram/ml), two penicillin-intermediate (MIC of 0.25 microgram/ml), and four penicillin-resistant (MIC of 2.0 to 4.0 micrograms/ml) strains of pneumococci: 6 of 10 strains were resistant to macrolides (MICs of > or = 0.5 microgram/ml). MICs of RP 59500 (0.5 to 1.0 microgram/ml), RPR 106972 (0.125 to 0.25 microgram/ml), and pyostacine (0.125 to 0.25 microgram/ml) did not alter with the strain's penicillin or macrolide susceptibility status. Three penicillin-susceptible strains and one penicillin-intermediate strain were susceptible to macrolides (MICs of < or = 0.25 microgram/ml); the macrolide MICs for the remaining strains were > or = 4.0 micrograms/ml. Cefotaxime MICs rose with those of penicillin G, but all strains were inhibited at MICs of < or = 2.0 micrograms/ml. RP 59500 was bactericidal for all strains after 24 h at 2 x MIC and yielded 90% killing of all strains at 6 h at 2 x MIC; at 8 x MIC, RP 59500 showed 90% killing of six strains within 10 min (approximately 0.2 h). In comparison, RPR 106972 was bactericidal for 9 of 10 strains at 2 x MIC after 24 h and yielded 90% killing of all strains at 2 x MIC after 6 h; 90% killing of six strains was found at 8 x MIC at 0.2 h. Results for pyostacine were similar to those of RPR 106972. Erythromycin and clarithromycin were bactericidal for three of four macrolide-susceptible strains after 24 h at 4 x MIC. Clarithromycin yielded 90% killing of three strains at 8 x MIC after 12 h. Cefotaxime was bactericidal for all strains after 24 h at 4 x MIC, yielding 90% killing of all strains after 6 h at 4 x MIC. All three streptogramins yielded rapid killing of penicillin- and erythromycin-susceptible and -resistant pneumococci and were the only compounds which killed significant numbers of strains at 0.2 h.
Efficacy of sparfloxacin and autoradiographic diffusion pattern of [14C]Sparfloxacin in experimental Staphylococcus aureus joint prosthesis infection
Authors: Crémieux A C , Mghir A S , Bleton R , Manteau M , Belmatoug N , Massias L , Garry L , Sales N , Mazière B , Carbon C
Published: October 2018

Using a new rabbit model of methicillin-susceptible Staphylococcus aureus knee prosthesis infection, we compared the efficacies of sparfloxacin (50 mg/kg of body weight subcutaneously, twice a day) and pefloxacin (50 mg/kg subcutaneously, twice a day). A partial knee replacement was performed with a silicone implant fitted into the intramedullary canal of the tibia, and 5 x 10(7) CFU of methicillin-susceptible S. aureus was injected into the knee. The 7-day treatment regimen was started 15 days later. The MICs and MBCs of sparfloxacin and pefloxacin were, respectively, 0.06 and 0.25 microgram/ml (MIC) and 0.25 and 1 microgram/ml (MBC). The peak levels of sparfloxacin and pefloxacin in serum were 3.6 and 21 micrograms/ml, respectively. Three weeks after the end of treatment, animals were sacrificed and tibias were removed, pulverized, and quantitatively cultured. In contrast to pefloxacin (3.61 +/- 1.64 log10 CFU/g of bone), sparfloxacin significantly reduced the bacterial density (2.12 +/- 1.1 log10 CFU/g of bone) (P = 0.01) in comparison with the level in controls (4.59 +/- 1.21 log10 CFU/g of bone), without selection of resistant variants. Sparfloxacin was significantly more effective than pefloxacin (P = 0.025). The autoradiographic pattern of [14C]sparfloxacin diffusion was studied in noninfected animals with prostheses and in infected animals 15 days after inoculation. Sixty minutes after completion of infusion of 250 microCi of [14C]sparfloxacin, in infected animals the highest levels of radioactivity were detected around the prosthesis, in femoral cartilage, and in articular ligaments. Radioactivity was slightly less intense in bone marrow and muscles and was very weak in compact bone. The distribution of sparfloxacin in uninfected rabbits was similar. Thus, sparfloxacin may represent a valid alternative therapy in these infections provided that it is carefully monitored for potential side effects.
Bactericidal activity of single dose of clarithromycin plus minocycline, with or without ofloxacin, against Mycobacterium leprae in patients
Authors: Ji B , Jamet P , Perani E G , Sow S , Lienhardt C , Petinon C , Grosset J H
Published: October 2018

Fifty patients with newly diagnosed lepromatous leprosy were allocated randomly to one of five groups and treated with either a month-long standard regimen of multidrug therapy (MDT) for multibacillary leprosy, a single dose of 600 mg of rifampin, a month-long regimen with the dapsone (DDS) and clofazimine (CLO) components of the standard MDT, or a single dose of 2,000 mg of clarithromycin (CLARI) plus 200 mg of minocycline (MINO), with or without the addition of 800 mg of ofloxacin (OFLO). At the end of 1 month, clinical improvement accompanied by significant decreases of morphological indexes in skin smears was observed in about half of the patients of each group. A significant bactericidal effect was demonstrated in the great majority of patients in all five groups by inoculating the footpads of mice with organisms recovered from biopsy samples obtained before and after treatment. Rifampin proved to be a bactericidal drug against Mycobacterium leprae more potent than any combination of the other drugs. A single dose of CLARI-MINO, with or without OFLO, displayed a degree of bactericidal activity similar to that of a regimen daily of doses of DDS-CLO for 1 month, suggesting that it may be possible to replace the DDS and CLO components of the MDT with a monthly dose of CLARI-MINO, with or without OFLO. However, gastrointestinal adverse events were quite frequent among patients treated with CLARI-MINO, with or without OFLO, and may be attributed to the higher dosage of CLARI or MINO or to the combination of CLARI-MINO plus OFLO. In future trials, therefore, we propose to reduce the dosages of the drugs to 1,000 mg of CLARI, 100 mg of MINO, and 400 mg of OFLO.
katG mutations in isoniazid-resistant Mycobacterium tuberculosis isolates recovered from Finnish patients
Authors: Marttila H J , Soini H , Huovinen P , Viljanen M K
Published: October 2018

katG and inhA genes from isoniazid-resistant Mycobacterium tuberculosis strains isolated in Finland were examined by PCR or sequencing. By PCR, katG was not detected in 3 of 54 strains. Sequencing of katG from 13 strains showed small point mutations or insertions; a previously described mutation causing a Ser-to-Thr change at position 315 was found in 4 strains, and there were nine new missense mutations of katG. A 209-bp segment of inhA from 17 strains was sequenced, but no mutations were observed. This result indicates that different mutations prevail in different geographical areas.
In vitro activities of trovafloxacin against 557 strains of anaerobic bacteria
Authors: Wexler H M , Molitoris E , Molitoris D , Finegold S M
Published: October 2018

The antimicrobial activity of trovafloxacin for 557 strains of anaerobic bacteria was determined by the National Committee for Clinical Laboratory Standards-approved Wadsworth agar dilution technique. The species tested included Bacteroides fragilis (n = 91), other members of the B. fragilis group (n = 130), Campylobacter gracilis (n = 15), other Bacteroides spp. (n = 16), Prevotella spp. (n = 49), Porphyromonas spp. (n = 15), Fusobacterium spp. (n = 62), Bilophila wadsworthia (n = 24), Sutterella wadsworthensis (n = 21), Clostridium spp. (n = 61), Peptostreptococcus spp. (n = 38), and gram-positive non-spore-forming rods (n = 35). Trovafloxacin inhibited all strains of B. fragilis at < or = 0.5 microgram/ml, 99% of other B. fragilis group species at < or = 2 micrograms/ml, and 96% of all anaerobes tested at < or = 2 micrograms/ml.
Inhibition of metallo-beta-lactamases by a series of mercaptoacetic acid thiol ester derivatives
Authors: Payne D J , Bateson J H , Gasson B C , Proctor D , Khushi T , Farmer T H , Tolson D A , Bell D , Skett P W , Marshall A C , Reid R , Ghosez L , Combret Y , Marchand-Brynaert J
Published: October 2018

A series of mercaptoacetic acid thiol esters have been identified as metallo-beta-lactamase inhibitors. Electrospray mass spectrometry (ESMS) has shown that irreversible inhibition of the Bacillus cereus II metallo-beta-lactamase by SB214751, SB214752, and SB213079 was concomitant with a 90-Da increase in mass of the enzyme. Tryptic digestion of the B. cereus II inhibited with SB214751 illustrated that the peptide fragment, containing the only cysteine of the enzyme, had undergone a mass increment of 90 Da. It was further demonstrated that B. cereus II hydrolyzed this type of compound across the thiol ester bond to yield mercaptoacetic acid. Mercaptoacetic acid is the only molecular fragment common to SB214751, SB214752, and SB213079, and free mercaptoacetic acid does not bind covalently to B. cereus II. Therefore, it is concluded that these compounds inhibit B. cereus II by the mechanism-based delivery of mercaptoacetic acid, forming a disulfide linkage with the active sites cysteine (predicted mass shift = +90 Da) under the aerobic conditions of the assay. The different thiol esters examined had a broad range of potencies against the metallo-beta-lactamases tested. For example SB214751, SB214752, and SB213079 all had 50% inhibitory concentrations of < 10 and > 1,000 microM for the Stenotrophomonas maltophilia L-1 and Bacteroides fragilis CfiA enzymes, respectively. SB216968 was particularly active against the Aeromonas hydrophila CphA metallo-beta-lactamase and was found to be an uncompetitive inhibitor of this enzyme (Ki = 3.9 microM), whereas it exhibited irreversible inhibition of the L-1 enzyme. These observations with this series of compounds have revealed subtle differences between the active sites of different metallo-beta-lactamases. Finally, a novel application for isothermal titration calorimetry for assessing the zinc chelating activity of candidate inhibitors is also presented.
Quinolone resistance locus nfxD of Escherichia coli is a mutant allele of the parE gene encoding a subunit of topoisomerase IV
Authors: Breines D M , Ouabdesselam S , Ng E Y , Tankovic J , Shah S , Soussy C J , Hooper D C
Published: October 2018

The locus nfxD, which contributes to high-level quinolone resistance in Escherichia coli KF111b (gyrAr nfxB nfxD), is only expressed in the presence of a gyrA mutation, and maps to the region of the parC and parE genes, was outcrossed into strain KF130, creating strain DH161 (gyrAr nfxD). DNA sequence analysis of DH161 revealed no changes in the topoisomerase IV parC quinolone resistance-determining region but did identify a single T-to-A mutation in parE at codon 445, leading to a change from Leu to His. Full-length cloned parE+ partially complemented the resistance phenotype in KF111b and DH161, but did not complement the resistance phenotype in strain KF130 (gyrAr). No complementation was seen with cloned, truncated parE+. To confirm these findings, gyrAr was first outcrossed from KF130 into E. coli W3110parE10 [parE temperature sensitive(Ts)] and KL16. The transduced strains KL16 and W3110parE10 were subsequently transformed with plasmids containing cloned parE from DH161 or KL16. Cloned parE from DH161 increased norfloxacin resistance in the parE(Ts) background twofold at 30 degrees C and fourfold at 42 degrees C compared to those for cloned parE from KL16. The same experiment with a non-Ts background revealed a twofold increase in the norfloxacin MIC at both 30 and 42 degrees C. These data identify the nfxD conditional resistance locus as a mutant allele of parE. This report is the first of a quinolone-resistant parE mutant and confirms the role of topoisomerase IV as a secondary target of norfloxacin in E. coli.
Antimicrobial activity and spectrum of LB20304, a novel fluoronaphthyridone
Authors: Cormican M G , Jones R N
Published: October 2018

Compound LB20304 is a fluoronaphthyridone carboxylic acid with a novel pyrrolidine substituent. This drug was compared with ciprofloxacin, levofloxacin, ofloxacin, and trovafloxacin against over 800 pathogens, most from blood stream infections, by National Committee for Clinical Laboratory Standards reference methods. LB20304 was the most active agent against gram-positive species including strains observed to be resistant to other fluoroquinolones and glycopeptides. The potency of LB20304 (MIC50, 0.03 micrograms/ml) against the Enterobacteriaceae was exceeded only by that of ciprofloxacin (0.015 micrograms/ml). It has limited activity against gram-negative anaerobes.
Cellular accumulation of the new ketolide RU 64004 by human neutrophils: comparison with that of azithromycin and roxithromycin
Authors: Vazifeh D , Abdelghaffar H , Labro M T
Published: October 2018

We analyzed the uptake of RU 64004 by human neutrophils (polymorphonuclear leukocytes [PMNs]) relative to those of azithromycin and roxithromycin. RU 64004 was strongly and rapidly accumulated by PMNs, with a cellular concentration/extracellular concentration ratio (C/E) of greater than 200 in the first 5 min, and this was followed by a plateau at 120 to 180 min, with a C/E of 461 +/- 14.8 (10 experiments) at 180 min. RU 64004 uptake was moderately sensitive to external pH, and activation energy was also moderate (63 +/- 3.8 kJ/mol). RU 64004 was mainly located in PMN granules (about 70%) and egressed slowly from loaded cells, owing to avid reuptake. The possibility that PMN uptake of RU 64004 and other macrolides occurs through a carrier-mediated system was suggested by three key results. First, there existed a strong interindividual variability in uptake kinetics, suggesting variability in the numbers or activity of a transport protein. Second, macrolide uptake displayed saturation kinetics characteristic of that of a carrier-mediated transport system: RU 64004 had the highest Vmax value (3,846 ng/2.5 x 10(6) PMNs/5 min) and the lowest Km value (about 28 microM), indicating a high affinity for the transporter. Third, as observed previously with other erythromycin A derivatives, Ni2+ (a blocker of the Na+/Ca2+ exchanger which mediates Ca2+ influx in resting neutrophils) impaired RU 64004 uptake by PMNs, with a 50% inhibitory concentration of about 3.5 mM. In addition, we found that an active process is also involved in macrolide efflux, because verapamil significantly potentiated the release of all three macrolides tested. This effect of verapamil does not seem to be related to an inhibition of Ca2+ influx, because neither EGTA [ethylene glycol-bis (beta-aminoethyl ether)-N,N',N'-tetraacetic acid] nor Ni2+ modified macrolide efflux. The nature and characteristics of the entry- and efflux-mediating carrier systems are under investigation.
In vivo efficacies of 5'-methylthioadenosine analogs as trypanocides
Authors: Bacchi C J , Sanabria K , Spiess A J , Vargas M , Marasco C J , Jimenez L M , Goldberg B , Sufrin J R
Published: October 2018

5'-Deoxy-5'-(methylthio)adenosine (MTA), a key by-product of polyamine biosynthesis, is cleaved by MTA phosphorylase and is salvaged as adenine and, through conversion of the ribose moiety, methionine. An analog of MTA, 5'-deoxy-5'-(hydroxyethylthio)adenosine (HETA), is a substrate for trypanosome MTA phosphorylase and is active in vitro and in vivo against Trypanosoma brucei brucei, an agent of bovine trypanosomiasis. In this study, HETA and three O-acylated HETA derivatives were examined for their activities against model infections of T. b. brucei and Trypanosoma brucei rhodesiense, the agent of East African sleeping sickness. HETA was curative (>60%) for infections caused by 5 of 11 clinical isolates of T. b. rhodesiense when it was given to mice at 200 mg/kg of body weight for 7 days as a continuous infusion in osmotic pumps. HETA at 150 to 200 mg/kg also extended the life spans of the mice infected with four additional isolates two- to fivefold. Di- and tri-O-acetylated derivatives of HETA also proved curative for the infections, while a tri-O-propionyl derivative, although also curative, was not as effective. This study indicates that substrate analogs of MTA should be given important consideration for development as novel chemotherapies against African trypanosomiasis.
In vitro antibacterial activity of LY333328, a new semisynthetic glycopeptide
Authors: Biavasco F , Vignaroli C , Lupidi R , Manso E , Facinelli B , Varaldo P E
Published: October 2018

LY333328 is a semisynthetic N-alkyl derivative of LY264826, a naturally occurring structural analog of vancomycin. LY333328 was evaluated for its in vitro inhibitory and bactericidal activities in comparison with those of the two currently available glycopeptides (vancomycin and teicoplanin). Glycopeptide-susceptible test strains included a total of 311 isolates (most of clinical origin) from the genera Staphylococcus, Enterococcus, Streptococcus, Aerococcus, Gemella, Lactococcus, Listeria, Corynebacterium, and Clostridium. Test strains resistant or intermediate to vancomycin and/or teicoplanin included 56 clinical isolates of Enterococcus (of the VanA, VanB, and VanC phenotypes) and 32 clinical isolates of Staphylococcus (S. haemolyticus, S. epidermidis, and S. aureus), 31 strains of gram-positive genera outside the spectrum of activity of vancomycin (Leuconostoc, Pediococcus, Lactobacillus, and Erysipelothrix), and laboratory-derived organisms obtained after exposure of susceptible Staphylococcus isolates to teicoplanin (6 strains) or laboratory-derived organisms with resistance determinants received from VanA enterococci (2 Enterococcus and 25 Listeria transconjugants). LY333328 was highly active against staphylococci, enterococci, and listeriae (whether they were clinical or laboratory-derived strains) resistant to the currently available glycopeptides. In particular, the MICs of LY333328 did not vary substantially between teicoplanin-susceptible and teicoplanin-resistant staphylococci and between vancomycin-susceptible and vancomycin-resistant enterococci. LY333328 demonstrated fairly good inhibitory activity even against most strains of Leuconostoc, Pediococcus, and Erysipelothrix (MIC range, 1 to 8 microg/ml), whereas it proved less active (although much more active than vancomycin or teicoplanin) against Lactobacillus strains. In minimal bactericidal concentration (MBC) and time-kill studies, LY333328 demonstrated excellent bactericidal activity; enterococci, in particular, which were largely tolerant of vancomycin and teicoplanin, were uniformly killed by LY333328, with MBC-to-MIC ratios of 4 to 8 for most vancomycin-susceptible and vancomycin-resistant strains. In attempts to select for resistant clones, no survivors stably growing in the presence of 10 microg of LY333328 per ml were obtained from the Staphylococcus and Enterococcus test strains exposed to the drug.
Effects of food and sucralfate on a single oral dose of 500 milligrams of levofloxacin in healthy subjects
Authors: Lee L J , Hafkin B , Lee I D , Hoh J , Dix R
Published: October 2018

The effects of food and sucralfate on the pharmacokinetics of levofloxacin following the administration of a single 500-mg oral dose were investigated in a randomized, three-way crossover study with young healthy subjects (12 males and 12 females). Levofloxacin was administered under three conditions: fasting, fed (immediately after a standardized high-fat breakfast), and fasting with sucralfate given 2 h following the administration of levofloxacin. The concentrations of levofloxacin in plasma and urine were determined by high-pressure liquid chromatography. By noncompartmental methods, the maximum concentration of drug in serum (Cmax), the time to Cmax (Tmax), the area under the concentration-time curve (AUC), half-life (t1/2), clearance (CL/F), renal clearance (CLR), and cumulative amount of levofloxacin in urine (Ae) were estimated. The individual profiles of the drug concentration in plasma showed little difference among the three treatments. The only consistent effect of the coadministration of levofloxacin with a high-fat meal for most subjects was that levofloxacin absorption was delayed and Cmax was slightly reduced (Tmax, 1.0 and 2.0 h for fasting and fed conditions, respectively [P = 0.002]; Cmax, 5.9 +/- 1.3 and 5.1 +/- 0.9 microg/ml [90% confidence interval = 0.79 to 0.94] for fasting and fed conditions, respectively). Sucralfate, which was administered 2 h after the administration of levofloxacin, appeared to have no effect on levofloxacin's disposition compared with that under the fasting condition. Mean values of Cmax and AUC from time zero to infinity were 6.7 +/- 3.2 microg/ml and 47.9 +/- 8.4 microg x h/ml, respectively, following the administration of sucralfate compared to values of 5.9 +/- 1.3 microg/ml and 50.5 +/- 8.1 microg x h/ml, respectively, under fasting conditions. The mean t1/2, CL/F, CLR, and Ae values were similar among all three treatment groups. In conclusion, the absorption of levofloxacin was slightly delayed by food, although the overall bioavailability of levofloxacin following a high-fat meal was not altered. Finally, sucralfate did not alter the disposition of levofloxacin when sucralfate was given 2 h after the administration of the antibacterial agent, thus preventing a potential drug-drug interaction.
In vitro activities of 10 antimicrobial agents against bacterial vaginosis-associated anaerobic isolates from pregnant Japanese and Thai women
Authors: Puapermpoonsiri S , Watanabe K , Kato N , Ueno K
Published: October 2018

The in vitro activities of 10 antimicrobial agents against 159 bacterial vaginosis-associated anaerobic isolates from pregnant Japanese and Thai women were determined. Clindamycin, imipenem, cefmetazole, amoxicillin, amoxicillin-clavulanate, and metronidazole were highly active against all anaerobic isolates except Prevotella bivia and Mobiluncus species, which were resistant to amoxicillin and metronidazole, respectively. Cefotiam, ceftazidime, and ofloxacin were variably effective, while cefaclor was the least effective agent.
Limiting deoxynucleoside triphosphate concentrations emphasize the processivity defect of lamivudine-resistant variants of human immunodeficiency virus type 1 reverse transcriptase
Authors: Back N K , Berkhout B
Published: October 2018

The nucleoside drug lamivudine (3TC) triggers the selection of resistant forms of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) with a substitution of amino acid 184Met. The 3TC-resistant RT enzymes 184Val and 184Ile exhibit a processivity defect in in vitro assays that correlates with reduced replication of the corresponding virus variants in primary cells. However, no replication defect is apparent for these two mutants in the transformed T-cell line SupT1. One obvious difference between the two cell types is the intracellular deoxynucleoside triphosphate (dNTP) level. Primary cells have a much smaller dNTP pool, and this cellular condition may emphasize the processivity defect of the codon 184 RT variants. Alternatively, cell-specific cofactors that influence the process of reverse transcription may exist. Such accessory factors may be packaged into the virion to exert an effect on the RT enzyme. To discriminate between these possibilities we performed additional assays with the wild-type and mutant RT enzymes. The RT proteins were either isolated from virions produced by primary and transformed cell types or expressed as recombinant protein. We also performed infection assays with cells treated with a drug that reduces the intracellular dNTP pool. Furthermore, reverse transcription was studied within virus particles in the endogenous assay, which allows for the manipulation of the dNTP level. The combined results indicate that the enzymatic defect of the 3TC-resistant HIV-1 variants is stressed at low dNTP concentrations.
Diazepam-mediated inhibition of human immunodeficiency virus type 1 expression in human brain cells
Authors: Lokensgard J R , Gekker G , Hu S , Arthur A F , Chao C C , Peterson P K
Published: October 2018

Treatment of acutely infected human brain cell and enriched microglial cell cultures with diazepam inhibited human immunodeficiency virus type 1 (HIV-1) p24 antigen expression. Similarly, diazepam suppressed HIV-1 expression in chronically infected promonocytic (U1) cells and acutely infected monocyte-derived macrophages, and this antiviral activity was associated with decreased activation of nuclear factor kappa B.
Nosocomial spread of cephem-resistant Escherichia coli strains carrying multiple Toho-1-like beta-lactamase genes
Authors: Yagi T , Kurokawa H , Senda K , Ichiyama S , Ito H , Ohsuka S , Shibayama K , Shimokata K , Kato N , Ohta M , Arakawa Y
Published: October 2018

Escherichia coli HKY56, which demonstrated resistance to various beta-lactams except carbapenems, was isolated from the throat swab of an inpatient in 1994. Conjugal transfer of cephem resistance from HKY56 to E. coli CSH2 was not successful. Three cefotaxime-resistant E. coli clones harboring plasmid pMRE001, pMRE002, or pMRE003, each of which carried a 3.4-, 5.8-, or 6.2-kb EcoRI fragment insert, respectively, were obtained from HKY56. Although restriction analysis suggested their different origins, these clones showed similar profiles of resistance to various beta-lactams. The sequence of 10 amino acid residues at the N terminus of beta-lactamase purified from E. coli HB101(pMRE001) was identical to that of Toho-1. This Toho-1-like beta-lactamase-1 (TLB-1) was able to hydrolyze cefoperazone and cefotaxime efficiently, but it failed to hydrolyze cephamycins. A Toho-1-specific DNA probe was hybridized with three distinct EcoRI fragments derived from the chromosomal DNA of strain HKY56, and these fragments corresponded to DNA inserts carried by pMRE001, pMRE002, and pMRE003, respectively. PCR and Southern hybridization analysis suggested that all six cephem-resistant E. coli strains, strains HKY273, HKY285, HKY288, HKY305, HKY316, and HKY335, which were isolated in 1996 at the same hospital where strain HKY56 had been isolated, also possessed multiple Toho-1-like beta-lactamase (TLB) genes, and the hybridization patterns obtained with the Toho-1-specific probe were quite similar among these six isolates. The DNA fingerprinting patterns observed by pulsed-field gel electrophoresis revealed that among the E. coli isolates tested, all isolates except HKY56 possessed a similar genetic background. These findings suggested that E. coli strains that carry chromosomally multiplied TLB genes may have been proliferating and transmitted among patients in the same hospital.
Population pharmacokinetic modeling of isoniazid, rifampin, and pyrazinamide
Authors: Peloquin C A , Jaresko G S , Yong C L , Keung A C , Bulpitt A E , Jelliffe R W
Published: October 2018

Isoniazid (INH), rifampin (RIF), and pyrazinamide (PZA) are the most important drugs for the treatment of tuberculosis (TB). The pharmacokinetics of all three drugs in the plasma of 24 healthy males were studied as part of a randomized cross-over phase I study of two dosage forms. Subjects ingested single doses of INH at 250 mg, RIF at 600 mg, and PZA at 1,500 mg. Plasma was collected for 36 h and was assayed by high-performance liquid chromatography. The data were analyzed by noncompartmental, iterative two-stage maximum a posteriori probability Bayesian (IT2B) and nonparametric expectation maximization (NPEM) population modeling methods. Fast and slow acetylators of INH had median peak concentrations in plasma (C[max]) of 2.44 and 3.64 microg/ml, respectively, both of which occurred at 1.0 h postdose (time of maximum concentrations of drugs in plasma [T(max)]), with median elimination half-lives (t1/2) of 1.2 and 3.3 h, respectively (by the NPEM method). RIF produced a median C(max) of 11.80 microg/ml, a T(max) of 1.0 h, and a t1/2 of 3.4 h. PZA produced a median C(max) of 28.80 microg/ml, a T(max) of 1.0 h, and a t1/2 of 10.0 h. The pharmacokinetic behaviors of INH, RIF, and PZA were well described by the three methods used. These models can serve as benchmarks for comparison with models for other populations, such as patients with TB or TB with AIDS.
SRR-SB3, a disulfide-containing macrolide that inhibits a late stage of the replicative cycle of human immunodeficiency virus
Authors: Witvrouw M , Balzarini J , Pannecouque C , Jhaumeer-Laulloo S , Esté J A , Schols D , Cherepanov P , Schmit J C , Debyser Z , Vandamme A M , Desmyter J , Ramadas S R , de Clercq E
Published: October 2018

From a series of macrocyclic diamides possessing the disulfide linkage, only SRR-SB3, a compound that complexes with zinc, was found to inhibit human immunodeficiency virus type 1 (HIV-1; strain IIIB) replication at a concentration of 1.8 to 6.5 micrograms/ml in MT-4, CEM, and peripheral blood mononuclear cells. SRR-SB3 was toxic to MT-4 cells at a concentration of 15.9 micrograms/ml, resulting in a selectivity index of 9 in these cells. This macrolide was also effective against various other HIV-1 strains, including clinical isolates and HIV-1 strains resistant to protease inhibitors and nucleoside and nonnucleoside reverse transcriptase inhibitors. It was also active against various HIV-2 strains, simian immunodeficiency virus (strain MAC251), and Moloney murine sarcoma virus, but not against viruses other than retroviruses. In addition, the compound was found to inhibit chronic HIV-1 infections in vitro. The compound in combination with other antiviral agents, such as zidovudine, zalcitabine, and stavudine, showed an effect that was between additive and synergistic. Time-of-addition experiments indicated that SRR-SB3 acts at a late stage of the HIV-1 replicative cycle.
Antibiotic resistance among clinical isolates of Haemophilus influenzae in the United States in 1994 and 1995 and detection of beta-lactamase-positive strains resistant to amoxicillin-clavulanate: results of a national multicenter surveillance study
Authors: Doern G V , Brueggemann A B , Pierce G , Holley H P , Rauch A
Published: October 2018

A total of 1,537 clinical isolates of Haemophilus influenzae were recovered in 30 U.S. medical center laboratories between 1 November 1994 and 30 April 1995 and were characterized in a central laboratory with respect to serotype and beta-lactamase production and the in vitro activities of 15 oral antimicrobial agents. Overall, 36.4% of the isolates were found to produce beta-lactamase. The rank order of activity of six cephalosporins on the basis of MICs was cefixime > cefpodoxime > cefuroxime > loracarbef > or = cefaclor > cefprozil. On the basis of current National Committee for Clinical Laboratory Standards (NCCLS) breakpoints ages of isolates found to be resistant or intermediate to these agents were as follows: 0.1, 0.3, 6.4, 16.3, 18.3, and 29.8, respectively (National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, 4th ed. M7-A4, 1995). Azithromycin was, on a weight basis, the most potent of the macrolides tested in this study, followed by erythromycin and then clarithromycin. Azithromycin was typically fourfold more active than erythromycin, which was, in turn, slightly more active than clarithromycin. However, when compared on the basis of the frequency of resistance determined by using current NCCLS breakpoints, there was essentially no difference between azithromycin and clarithromycin, i.e., 0.5 and 1.9%, respectively (P = 0.086). Interpretive breakpoints for erythromycin MIC tests versus H. influenzae have not been developed. Resistance to other non- beta-lactam agents was variable, as follows: trimethoprim-sulfamethoxazole, 9.0%; chloramphenicol, 0.2%; tetracycline, 1.3%; and rifampin, 0.3%. Two conspicuous findings in this study were the identification of 39 strains H. influenzae that were beta-lactamase negative but ampicillin intermediate or resistant (BLNAR) and, even more surprisingly, 17 beta-lactamase-positive isolates that were resistant to amoxicillin-clavulanate (BLPACR). Strains of H. influenzae in the first group have heretofore been very uncommon; organisms in the second group have not previously been described in the literature. The percentages of all study isolates comprised of BLNAR and BLPACR organisms were 2.5 and 1.1, respectively. Overall resistance to ampicillin was thus 38.9%, and that to amoxicillin-clavulanate was 4.5%.
A cytotoxicity assay for evaluation of candidate anti-Pneumocystis carinii agents
Authors: Cushion M T , Chen F , Kloepfer N
Published: October 2018

A series of over 60 agents representing several different classes of compounds were evaluated for their effects on the ATP pools of Pneumocystis carinii populations derived from immunosuppressed rats. A cytotoxicity assay based on an ATP-driven bioluminescent reaction was used to determine the concentration of agent which decreased the P. carinii ATP pools by 50% versus untreated controls (IC50). A ranking system based on the IC50 value was devised for comparison of relative responses among the compounds evaluated in the cytotoxic assay and for comparison to in vivo efficacy. With few exceptions, there was a strong correlation between results from the ATP assay and the performance of the compound in vivo. Antibiotics, with the exception of trimethoprim-sulfamethoxazole (TMP-SMX), were ineffective at reducing the ATP pools and were not active clinically or in the rat model of P. carinii pneumonia. Likewise, other agents not expected to be effective, e.g., antiviral compounds, did not show activity. Standard anti-P. carinii compounds, e.g., TMP-SMX, pentamidine, and dapsone, dramatically reduced ATP levels. Analogs of the quinone and topoisomerase inhibitor groups were shown to reduce ATP concentrations and hold promise for further in vivo investigation. The cytotoxicity assay provides a rapid assessment of response, does not rely on replicating organisms, and should be useful for assessment of structure-function relationships.
The human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein zinc ejection activity of disulfide benzamides and benzisothiazolones: correlation with anti-HIV and virucidal activities
Authors: Tummino P J , Harvey P J , McQuade T , Domagala J , Gogliotti R , Sanchez J , Song Y , Hupe D
Published: October 2018

It has been shown previously by our group and others that a series of four disulfide benzamides with cellular anti-human immunodeficiency virus (HIV) activity can eject zinc from HIV type 1 nucleocapsid protein (NCp7) in vitro while analogs without antiviral activity do not. We also found that the zinc ejection activity correlates with the loss of the ability of NCp7 to bind to HIV psi RNA in vitro. These observations indicate that the antiviral disulfide benzamides may act at a novel retroviral target of action, i.e., the nucleocapsid protein. The present studies examine the relationship among disulfide benzamide structure, in vitro NCp7 zinc ejection activity, and antiviral activity for a larger series of compounds. All of the antiviral disulfide benzamides were found to eject NCp7 zinc, while some disulfide benzamides with zinc ejection activity are not antiviral. Utilizing the thiol reagent 5,5'-dithiobis(2-nitrobenzoic acid), it was determined that the o-amido-phenyl disulfides being studied cyclize in aqueous solution to form benzisothiazolones. A series of benzisothiazolones, which are stable in solution in the absence of dithiothreitol, were found to eject NCp7 zinc at a rate similar to that of their disulfide benzamide analogs and to possess similar antiviral activity. It was also found that the relative rates of HIV inactivation by various disulfide benzamides and benzisothiazolones correlate with their relative kinetic rates of NCp7 zinc ejection, which is consistent with the nucleocapsid protein being the target of action of these compounds.
Induction of ermSV by 16-membered-ring macrolide antibiotics
Authors: Kamimiya S , Weisblum B
Published: October 2018

The erm family of 23S rRNA adenine-N6-methyltransferases confers resistance to all macrolide-lincosamide-streptograminB (MLS) antibiotics, but not all MLS antibiotics induce synthesis of Erm methyltransferase with equal efficiency in a given organism. The induction efficiency of a test panel of MLS antibiotics was studied by using two translational attenuator-lac reporter gene fusion constructs, one based on ermSV from Streptomyces viridochromogenes NRRL 2860 and the other based on ermC from Staphylococcus aureus RN2442. Four types of responses which were correlated with the macrolide ring size were seen, as follows: group 1, both ermSV and ermC were induced by the 14-membered-ring macrolides erythromycin, lankamycin, and matromycin, as well as by the lincosamide celesticetin; group 2, neither ermSV nor ermC was induced by the 12-membered-ring macrolide methymycin or by the lincosamide lincomycin or the streptogramin type B antibiotic ostreogrycin B; group 3, ermSV was selectively induced over ermC by the 16-membered-ring macrolides carbomycin, chalcomycin, cirramycin, kitasamycin, maridomycin, and tylosin; and group 4, ermC was selectively induced over ermSV by the 14-membered-ring macrolide megalomicin. These data suggest that the leader peptide determines the specificity of induction by different classes of MLS antibiotics and that for a given attenuator, a major factor which determines whether a given macrolide induces resistance is its size.
Bactericidal activity of low-dose clindamycin administered at 8- and 12-hour intervals against Staphylococcus aureus, Streptococcus pneumoniae, and Bacteroides fragilis
Authors: Klepser M E , Nicolau D P , Quintiliani R , Nightingale C H
Published: October 2018

Twelve volunteers received 300 mg of clindamycin intravenously (i.v.) or orally (p.o.) administered every 8 h (q8h) or q12h by random assignment over four study periods. Serum bactericidal titers were determined for each regimen against two isolates each of Staphylococcus aureus, Streptococcus pneumoniae (one penicillin-sensitive isolate and one penicillin-resistant isolate), and Bacteroides fragilis. The duration of measurable bactericidal activity over the dosing interval (expressed as a percentage of the dosing interval) was determined for each isolate. No significant differences in the duration of activity were observed between i.v. and p.o. regimens dosed according to the same interval (P > 0.05). All regimens provided bactericidal activity against S. pneumoniae for 100% of their respective dosing intervals. Against B. fragilis, bactericidal activity was observed for greater than 80% of the dosing interval for each of the regimens. Although a statistically significant difference favoring the q8h i.v. regimen (P < 0.05) was detected, this difference is not believed to be clinically significant. The q8h and q12h regimens provided measurable bactericidal activity against S. aureus for greater than 85 and 50% of the dosing intervals, respectively (P < 0.001). Clindamycin dosed at 300 mg i.v. or p.o., q8h or q12h, provides adequate coverage against S. aureus, S. pneumoniae, and B. fragilis.