bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping the regions carrying the three contiguous antibiotic resistance genes aadE, sat4, and aphA-3 in the genomes of staphylococci
Authors: Derbise A , Aubert S , El Solh N
Published: October 2018

Tn5405 (12 kb) is a staphylococcal composite transposon delimited by two inverted copies of IS1182, one of which contains IS1181. The internal part of this transposon carries three antibiotic resistance genes, aphA-3, aadE, and sat4, and three open reading frames (ORFs), orfx, orfy, and orfz, of unknown function. The dispersion of Tn5405 and the genes and ORFs included in this transposon were investigated in 50 epidemiologically unrelated staphylococci carrying aphA-3. Twenty-three maps, distinguishable by the presence or absence of the investigated genes or ORFs and/or by the sizes of the restriction fragments carrying them, were identified. Four isolates carried Tn5405, and 15 other isolates contained a Tn5405-related element. IS1182 was not detected in the aphA-3 regions mapped in 31 isolates which carried the following combinations: orfx, orfy, aadE, sat4, and aphA-3 +/- orfz; orfy, aadE, sat4, and aphA-3 +/- orfz; and aadE, sat4, aphA-3, and orfz. In all isolates, the genes and ORFs investigated were in relative positions similar to those in Tn5405. Thus, the internal part of Tn5405 appeared to be partially conserved with the maintenance, in all of the isolates, of at least the three antibiotic resistance genes.
Antianaerobic activity of the ketolide RU 64004 compared to activities of four macrolides, five beta-lactams, clindamycin, and metronidazole
Authors: Ednie L M , Spangler S K , Jacobs M R , Appelbaum P C
Published: October 2018

Agar dilution methodology (with added Oxyrase in the case of the macrolide group to allow incubation without added CO2) was used to compare the activity of RU 64004, a new ketolide, with the activities of erythromycin, azithromycin, clarithromycin, roxithromycin, clindamycin, amoxicillin with and without clavulanate, piperacillin with and without tazobactam, metronidazole, and imipenem against 379 anaerobes. Overall, RU 64004 yielded an MIC at which 50% of the isolates are inhibited (MIC50) of 1.0 microg/ml and an MIC90 of 16.0 microg/ml. In comparison, MIC50s and MIC90s of erythromycin, azithromycin, clarithromycin, and roxithromycin were 2.0 to 8.0 and >64.0 microg/ml, respectively. MICs of macrolides, including RU 64004, were higher for Bacteroides ovatus, Fusobacterium varium, Fusobacterium mortiferum, and Clostridium difficile than for the other species. RU 64004 was more active against gram-positive rods and cocci, Prevotella and Porphyromonas spp., and fusobacteria other than F. mortiferum and F. varium than against the Bacteroides fragilis group. Overall MIC50s and MIC90s (in micrograms per milliliter), respectively, of other compounds were as follows: clindamycin, 1.0 and 16.0; amoxicillin, 4.0 and 64.0; amoxicillin-clavulanate, 0.5 and 4.0; piperacillin, 8.0 and >64.0; piperacillin-tazobactam, 1.0 and 16.0; metronidazole, 1.0 and 4.0; and imipenem, 0.25 and 1.0.
Unique intracellular activation of the potent anti-human immunodeficiency virus agent 1592U89
Authors: Faletto M B , Miller W H , Garvey E P , St Clair M H , Daluge S M , Good S S
Published: October 2018

The anabolism of 1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, a selective inhibitor of human immunodeficiency virus (HIV), was characterized in human T-lymphoblastoid CD4+ CEM cells. 1592U89 was ultimately anabolized to the triphosphate (TP) of the guanine analog (-)-carbovir (CBV), a potent inhibitor of HIV reverse transcriptase. However, less than 2% of intracellular 1592U89 was converted to CBV, an amount insufficient to account for the CBV-TP levels observed. 1592U89 was anabolized to its 5'-monophosphate (MP) by the recently characterized enzyme adenosine phosphotransferase, but neither its diphosphate (DP) nor its TP was detected. The MP, DP, and TP of CBV were found in cells incubated with either 1592U89 or CBV, with CBV-TP being the major phosphorylated species. We confirmed that CBV is phosphorylated by 5'-nucleotidase and that mycophenolic acid increased the formation of CBV-TP from CBV 75-fold. However, mycophenolic acid did not stimulate 1592U89 anabolism to CBV-TP. The adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) did not inhibit CBV-TP formation from CBV or 1592U89, whereas the adenylate deaminase inhibitor 2'-deoxycoformycin selectively inhibited 1592U89 anabolism to CBV-TP and reversed the antiviral activity of 1592U89. 1592U89-MP was not a substrate for adenylate deaminase but was a substrate for a distinct cytosolic deaminase that was inhibited by 2'-deoxycoformycin-5'-MP. Thus, 1592U89 is phosphorylated by adenosine phosphotransferase to 1592U89-MP, which is converted by a novel cytosolic enzyme to CBV-MP. CBV-MP is then further phosphorylated to CBV-TP by cellular kinases. This unique activation pathway enables 1592U89 to overcome the pharmacokinetic and toxicological deficiencies of CBV while maintaining potent and selective anti-HIV activity.
Teicoplanin in cardiac surgery: intraoperative pharmacokinetics and concentrations in cardiac and mediastinal tissues
Authors: Martin C , Bourget P , Alaya M , Sertin A , Atlani C , Ennabli K , Said R
Published: October 2018

The concentrations of teicoplanin in the sera and mediastinal and heart tissues of 23 patients undergoing cardiac surgery were measured after two regimens of teicoplanin administration. Intraoperative pharmacokinetic parameters were also obtained. Patients were randomized into two groups. Those in group 1 were given teicoplanin at 6 mg x kg(-1) intravenously at the time of induction of anesthesia. Patients in group 2 were given teicoplanin at 12 mg x kg(-1) during the same period. The maximum concentration in serum (71 +/- 20 and 131 +/- 44 mg x l(-1)), the minimum concentration in serum (3.6 +/- 1.3 and 6.8 +/- 2.1 mg x l(-1)), the area under the concentration-time curve (AUC) from 0 to 12 h (108 +/- 20 and 217 +/- 38 microg x h x ml(-1)), and the AUC from 0 h to infinity (154 +/- 36 and 292 +/- 77 microg x h x ml(-1)) were twice as high after 12-mg x kg(-1) injections as after 6-mg x kg(-1) injections. No differences in mean residence time (9.7 +/- 4.9 and 8.4 +/- 2.7 h) or terminal half-life (8.5 +/- 3.8 and 7.5 +/- 2.3 h) were observed. Teicoplanin penetrated mediastinal and heart tissues but not sternal bone, where the antibiotic was detectable in only 1 of 13 patients in group 1 and 2 of 10 patients in group 2. In group 1, 7 of 13 patients had teicoplanin concentrations in tissue that were lower than the MIC for 90% of the strains of potential pathogens tested (MIC90) that cause infection after cardiac surgery. All of the patients in group 2 but one had teicoplanin concentrations in tissue (other than in sternal bone) far in excess of the MIC90 for the potential pathogens. In conclusion, the 12-mg x kg(-1) regimen of teicoplanin is followed by a significant increase in teicoplanin concentrations in heart and mediastinal tissues and should be preferred to the 6-mg x kg(-1) regimen if teicoplanin is selected for antimicrobial prophylaxis in open heart surgery.
In vitro activity of RU 64004, a new ketolide antibiotic, against gram-positive bacteria
Authors: Schülin T , Wennersten C B , Moellering R C , Eliopoulos G M
Published: October 2018

The comparative in vitro activity of RU 64004 (also known as HMR 3004), a new ketolide antibiotic, was tested by agar dilution against approximately 500 gram-positive organisms, including multiply resistant enterococci, streptococci, and staphylococci. All streptococci were inhibited by < or = 1 microg of RU 64004 per ml. The ketolide was more potent than other macrolides against erythromycin A-susceptible staphylococci and was generally more potent than clindamycin against erythromycin A-resistant strains susceptible to this agent. Clindamycin-resistant staphylococci (MIC, > 128 microg/ml) proved resistant to the ketolide, but some erythromycin A- and clindamycin-resistant enterococci remained susceptible to RU 64004.
Essential role of endogenously synthesized tylosin for induction of ermSF in Streptomyces fradiae
Authors: Memili E , Weisblum B
Published: October 2018

We compared ermSF induction in wild-type Streptomyces fradiae NRRL B-2702 and that in GS-14, a tylA mutant which cannot synthesize tylosin. Our findings suggest that (i) endogenously synthesized tylosin plays an obligatory role in ermSF induction and (ii) tylosin, or a biosynthetic intermediate beyond tylactone, has an "autocrine" function that induces ErmSF synthesis, thereby enabling S. fradiae to resist higher levels of tylosin.
Comparative in vitro antimicrobial susceptibilities of nosocomial isolates of Acinetobacter baumannii and synergistic activities of nine antimicrobial combinations
Authors: Marques M B , Brookings E S , Moser S A , Sonke P B , Waites K B
Published: October 2018

The in vitro susceptibilities of 69 nosocomial Acinetobacter isolates were determined by the broth microdilution method. Fourteen (20%) isolates were resistant to at least two aminoglycosides and two extended-spectrum penicillins. Nine antimicrobial combinations were then tested for synergy against these 14 isolates by checkerboard titration: imipenem with ciprofloxacin, amikacin, and tobramycin and ampicillin-sulbactam, piperacillin-tazobactam, and ticarcillin-clavulanate with amikacin and tobramycin. Synergy was detected with one or more antimicrobial combinations against 9 of 14 (64%) isolates, partial synergy was detected with one or more combinations against all 14 isolates, and an additive effect alone was observed with two different combinations against two isolates. No antagonism was detected with any combination. Imipenem plus either amikacin or tobramycin resulted in a synergistic or partial synergistic response against all 14 isolates. Specific combinations showing synergy against A. baumannii isolates were imipenem with tobramycin (four isolates), imipenem with amikacin (three isolates), ampicillin-sulbactam with tobramycin (six isolates), ampicillin-sulbactam with amikacin (three isolates), and ticarcillin-clavulanate with tobramycin (one isolate). Genotyping by randomly amplified polymorphic DNA analysis showed that 9 of the 14 isolates were of one strain, 4 isolates were of a second strain, and the remaining isolate was of a different strain. Eight of 14 (57%) patients infected with resistant A. baumannii isolates died. Only 3 of 14 patients had received a therapeutic regimen which was tested for synergy. Clinical studies are needed to determine the significance of these findings.
Activity of trovafloxacin in combination with other drugs for treatment of acute murine toxoplasmosis
Authors: Khan A A , Slifer T , Araujo F G , Polzer R J , Remington J S
Published: October 2018

Current therapy for toxoplasmosis with a synergistic combination of pyrimethamine plus sulfadiazine or pyrimethamine plus clindamycin is not always efficacious and is frequently discontinued due to intolerable toxic effects in immunocompromised individuals, particularly those with AIDS. Trovafloxacin, a new fluoroquinolone with potent activity against Toxoplasma gondii, was examined for potential synergistic activity when combined with other drugs used for treatment of human toxoplasmosis. Combinations of trovafloxacin with clarithromycin, pyrimethamine, or sulfadiazine demonstrated significantly enhanced activities compared to those observed with each drug alone. Our results suggest that combinations of trovafloxacin and other anti-toxoplasma drugs should be further explored for treatment of toxoplasmosis in humans.
Pharmacokinetics of oral fluconazole when used for prophylaxis in bone marrow transplant recipients
Authors: El-Yazigi A , Ellis M , Ernst P , Spence D , Hussain R , Baillie F J
Published: October 2018

The pharmacokinetics of fluconazole was investigated in 20 bone marrow transplant patients following oral administration of 200 mg of this drug. Blood samples were collected from each patient at different time intervals within 48 h after the first dose, and fluconazole was measured in plasma by high-performance liquid chromatography with UV detection. Urine was collected from 14 of these patients and analyzed similarly. The plasma concentration-time data exhibited the characteristics of the one-compartment model with first-order absorption quite well. The means +/- standard deviations of half-lives for absorption and elimination, peak concentration, time to peak, mean residence time, apparent volumes of distribution, area under the curve, and apparent oral clearance observed in these patients were 2.84 +/- 1.34 h, 19.94 +/- 18.7 h, 4.45 +/- 1.86 microg/ml, 8.34 +/- 5.97 h, 39.57 +/- 20.5 h, 0.874 +/- 0.48 liter/kg, 156.0 +/- 60.6 microg x h/ml, and 0.0256 +/- 0.0138 liter/h x kg, respectively. The amount of fluconazole excreted in urine in 24 h was 67.1 +/- 83 mg, which represents 33.55% +/- 41.6% of the dose administered. Patients who developed hemorrhagic cystitis excreted significantly (P < or = 0.0094) more fluconazole in 24 h than did those who did not.
Pharmacokinetics of intramuscularly administered aminosidine in healthy subjects
Authors: Kanyok T P , Killian A D , Rodvold K A , Danziger L H
Published: October 2018

Aminosidine is an older, broad-spectrum aminoglycoside antibiotic that has been shown to be effective in in vitro and animal models against multiple-drug-resistant tuberculosis and the Mycobacterium avium complex. The objective of this randomized, parallel trial was to characterize the single-dose pharmacokinetics of aminosidine sulfate in healthy subjects (eight males, eight females). Sixteen adults (mean [+/- standard deviation] age, 27.6 +/- 5.6 years) were randomly allocated to receive a single, intramuscular aminosidine sulfate injection at a dose of 12 or 15 mg/kg of body weight. Serial plasma and urine samples were collected over a 24-h period and used to determine aminosidine concentrations by high-performance liquid chromatographic assay. A one-compartment model with first-order input, first-order output, and a lag time (Tlag) and with a weighting factor of 1/y2 best described the data. Compartmental and noncompartmental pharmacokinetic parameters were estimated with the microcomputer program WinNonlin. One subject was not included (15-mg/kg group) because of the lack of sampling time data. On average, subjects attained peak concentrations of 22.4 +/- 3.2 microg/ml at 1.34 +/- 0.45 h. All subjects had plasma aminosidine concentrations below 2 microg/ml at 12 h, and all but two subjects (one in each dosing group) had undetectable plasma aminosidine concentrations at 24 h. The dose-adjusted area under the concentration-time curve from 0 h to infinity of aminosidine was identical for the 12- and 15-mg/kg groups (9.29 +/- 1.5 versus 9.29 +/- 2.2 microg x h/ml per mg/kg; P = 0.998). Similarly, no significant differences (P > 0.05) were observed between dosing groups for peak aminosidine concentration in plasma, time to peak aminosidine concentration in plasma, Tlag, apparent clearance, renal clearance, elimination rate constant, and elimination half-life. A significant difference was observed for the volume of distribution (0.35 versus 0.41 liters/kg; P = 0.037) between the 12 and 15 mg/kg dosing groups. Now that comparable pharmacokinetic profiles between dosing groups have been demonstrated, therapeutic equivalency testing via in vitro pharmacokinetic and pharmacodynamic modelling and randomized clinical trials in humans should be conducted.
SCH 48973: a potent, broad-spectrum, antienterovirus compound
Authors: Buontempo P J , Cox S , Wright-Minogue J , DeMartino J L , Skelton A M , Ferrari E , Albin R , Rozhon E J , Girijavallabhan V , Modlin J F , O'Connell J F
Published: October 2018

SCH 48973 is a novel molecule with potent, selective, antienterovirus activity. In assays of the cytopathic effect against five picornaviruses, SCH 48973 had antiviral activity (50% inhibitory concentrations [IC50s]) of 0.02 to 0.11 microg/ml, with no detectable cytotoxicity at 50 microg/ml. SCH 48973 inhibited 80% of 154 recent human enterovirus isolates at an IC50 of 0.9 microg/ml. The antiviral activity of SCH 48973 is derived from its specific interaction with viral capsid, as confirmed by competition binding studies. The affinity constant (Ki) for SCH 48973 binding to poliovirus was 8.85 x 10(-8) M. In kinetic studies, a maximum of approximately 44 molecules of SCH 48973 were bound to poliovirus capsid. SCH 48973 demonstrated efficacy in a murine poliovirus model of enterovirus disease. SCH 48973 increased the survival of infected mice when it was administered orally at dosages of 3 to 20 mg/kg of body weight/day. Oral administration of SCH 48973 also reduced viral titers in the brains of infected mice. On the basis of its in vitro and in vivo profiles, SCH 48973 represents a potential candidate for therapeutic intervention against enterovirus infections.
Potent and selective inhibition of human immunodeficiency virus type 1 transcription by piperazinyloxoquinoline derivatives
Authors: Baba M , Okamoto M , Makino M , Kimura Y , Ikeuchi T , Sakaguchi T , Okamoto T
Published: October 2018

We have found novel piperazinyloxoquinoline derivatives to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in both acutely and chronically infected cells. 8-Difluoromethoxy-1-ethyl-6-fluoro-1,4-didehydro-7-[4-(2-met hoxyphenyl)-1-piperazinyl]-4-oxoquinoline-3-carboxylic acid (K-12), the most potent congener of the series, completely inhibited HIV-1 replication in acutely infected MOLT-4 cells at a concentration of 0.16 to 0.8 microM without showing any cytotoxicity. The compound completely suppressed tumor necrosis factor alpha (TNF-alpha)-induced HIV-1 expression in latently infected cells (OM-10.1) and constitutive viral production in chronically infected cells (MOLT-4/III(B)) at a concentration of 0.8 microM. K-12 could also inhibit HIV-1 antigen expression in OM-10.1 and MOLT-4/III(B) cells at this concentration. Northern blot analysis revealed that K-12 selectively prevented the accumulation of HIV-1 mRNA in MOLT-4/III(B) and TNF-alpha-treated OM-10.1 cells in a dose-dependent fashion. It was not inhibitory to HIV-1 Tat or the cellular transcription factors NF-kappaB and Sp1, suggesting that the piperazinyloxoquinoline derivatives are a group of HIV-1 transcription inhibitors with a unique mechanism of action.
Penetration of trovafloxacin into cerebrospinal fluid in humans following intravenous infusion of alatrofloxacin
Authors: Cutler N R , Vincent J , Jhee S S , Teng R , Wardle T , Lucas G , Dogolo L C , Sramek J J
Published: October 2018

A single-dose study was conducted to determine concentrations of trovafloxacin (CP-99,219) achieved in the cerebrospinal fluid (CSF) relative to those in the serum of healthy subjects after intravenous infusion of alatrofloxacin (CP-116,517), the alanyl-alanyl prodrug of trovafloxacin. Twelve healthy subjects were administered single doses of alatrofloxacin at a trovafloxacin equivalent of 300 mg as an intravenous infusion over 1.0 h. CSF samples were taken by lumbar puncture at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 24 h after the start of the infusion; each subject was sampled at only one time point. Serum samples were taken from each subject at the time of CSF collection. A mean concentration of 5.8 microg of trovafloxacin per ml was present in serum 1.0 h after the start of the infusion. CSF/serum ratios ranged from 0.14 to 0.33 in the postdistribution phase (5 to 24 h postinfusion), with a mean ratio of 0.25. The most common adverse events were dizziness, nausea, and rash and were mild or moderate in intensity. The potency of trovafloxacin against susceptible organisms, coupled with its rapid penetration of CSF following the intravenous administration of alatrofloxacin, suggests that it may be useful in the treatment of bacterial meningitis in humans.
Pseudomonas aeruginosa isolates from patients with cystic fibrosis have different beta-lactamase expression phenotypes but are homogeneous in the ampC-ampR genetic region
Authors: Campbell J I , Ciofu O , Høiby N
Published: October 2018

Pseudomonas aeruginosa isolates from 1 of 17 cystic fibrosis patients produced secondary beta-lactamase in addition to the ampC beta-lactamase. Isolates were grouped into three beta-lactamase expression phenotypes: (i) beta-lactam sensitive, low basal levels and inducible beta-lactamase production; (ii) beta-lactam resistant, moderate basal levels and hyperinducible beta-lactamase production; (iii) beta-lactam resistant, high basal levels and constitutive beta-lactamase production. Apart from a base substitution in the ampR-ampC intergenic region of an isolate with moderate-basal-level and hyperinducible beta-lactamase production, sensitive and resistant strains were identical in their ampC-ampR genetic regions. Thus, enhanced beta-lactamase expression is due to mutations in regulatory proteins other than AmpR.
Intrapulmonary steady-state concentrations of clarithromycin and azithromycin in healthy adult volunteers
Authors: Rodvold K A , Gotfried M H , Danziger L H , Servi R J
Published: October 2018

The steady-state concentrations of clarithromycin and azithromycin in plasma were compared with concomitant concentrations in epithelial lining fluid (ELF) and alveolar macrophages (AM) obtained in intrapulmonary samples during bronchoscopy and bronchoalveolar lavage from 40 healthy, nonsmoking adult volunteers. Mean plasma clarithromycin, 14-(R)-hydroxyclarithromycin, and azithromycin concentrations were similar to those previously reported. Clarithromycin was extensively concentrated in ELF (range of mean +/- standard deviation concentrations, 34.4 +/- 29.3 microg/ml at 4 h to 4.6 +/- 3.7 microg/ml at 24 h) and AM (480 +/- 533 microg/ml at 4 h to 99 +/- 50 microg/ml at 24 h). The concentrations of azithromycin in ELF were 1.01 +/- 0.45 microg/ml at 4 h to 1.22 +/- 0.59 microg/ml at 24 h, and those in AM were 42.7 +/- 28.7 microg/ml at 4 h to 41.7 +/- 12.1 microg/ml at 24 h. The concentrations of 14-(R)-hydroxyclarithromycin in the AM ranged from 89.3 +/- 52.8 microg/ml at 4 h to 31.3 +/- 17.7 microg/ml at 24 h. During the period of 24 h after drug administration, azithromycin and clarithromycin achieved mean concentrations in ELF and AM higher than the concomitant concentrations in plasma.
Identification of BMS-200475 as a potent and selective inhibitor of hepatitis B virus
Authors: Innaimo S F , Seifer M , Bisacchi G S , Standring D N , Zahler R , Colonno R J
Published: October 2018

BMS-200475 is a novel carbocyclic 2'-deoxyguanosine analog found to possess potent and selective anti-hepatitis B virus (anti-HBV) activity. BMS-200475 is distinguished from guanosine by replacement of the natural furanose oxygen on the sugar moiety with an exo carbon-carbon double bond. In the HepG2 stably transfected cell line 2.2.15, BMS-200475 had a 50% effective concentration (EC50) of 3.75 nM against HBV, as determined by analysis of secreted HBV DNA. Structurally related compounds with adenine, iodouracil, or thymine base substitutions were significantly less potent or were inactive. Direct comparison of the antiviral activities of BMS-200475 with those of a variety of other nucleoside analogs, including lamivudine (EC50 = 116.26 nM), demonstrated the clearly superior in vitro potency of BMS-200475 in 2.2.15 cells. Intracellular HBV replicative intermediates were uniformly reduced when cells were treated with BMS-200475, but rebounded after treatment was terminated. The concentration of BMS-200475 causing 50% cytotoxicity in 2.2.15 cell cultures was 30 microM, approximately 8,000-fold greater than the concentration required to inhibit HBV replication in the same cell line. Treatment with BMS-200475 resulted in no apparent inhibitory effects on mitochondrial DNA content.
The presence of an R467K amino acid substitution and loss of allelic variation correlate with an azole-resistant lanosterol 14alpha demethylase in Candida albicans
Authors: White T C
Published: October 2018

Azole resistance in the pathogenic yeast Candida albicans is an emerging problem in the human immunodeficiency virus (HIV)-infected population. The target enzyme of the azole drugs is lanosterol 14alpha demethylase (Erg16p), a cytochrome P-450 enzyme in the biosynthetic pathway of ergosterol. Biochemical analysis demonstrates that Erg16p became less susceptible to fluconazole in isolate 13 in a series of isolates from an HIV-infected patient. PCR-single-strand conformation polymorphism (PCR-SSCP) analysis was used to scan for genomic alterations of ERG16 in the isolates that would cause this change in the enzyme in isolate 13. Alterations near the 3' end of the gene that were identified by PCR-SSCP were confirmed by DNA sequencing. A single amino acid substitution (R467K) that occurred in isolate 13 was identified in both alleles of ERG16. Allelic differences within the ERG16 gene, in the ERG16 promoter, and in the downstream THR1 gene were eliminated in isolate 13. The loss of allelic variation in this region of the genome is most likely the result of mitotic recombination or gene conversion. The R467K mutation and loss of allelic variation that occur in isolate 13 are likely responsible for the azole-resistant enzyme activity seen in this and subsequent isolates. The description of R467K represents the first point mutation to be identified within ERG16 of a clinical isolate of C. albicans that alters the fluconazole sensitivity of the enzyme.
Comparative effectiveness and safety of cefdinir and amoxicillin-clavulanate in treatment of acute community-acquired bacterial sinusitis. Cefdinir Sinusitis Study Group
Authors: Gwaltney J M , Savolainen S , Rivas P , Schenk P , Scheld W M , Sydnor A , Keyserling C , Leigh A , Tack K J
Published: October 2018

Cefdinir is an extended-spectrum oral cephalosporin that is active against pathogens commonly seen in acute community-acquired bacterial sinusitis (ACABS), including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Two randomized, investigator-blind, multicenter trials (one in the United States and one in Europe) compared two dosage regimens of cefdinir (600 mg once a day for 10 days and 300 mg twice a day for 10 days) to amoxicillin-clavulanate (A-C) (500 mg three times a day for 10 days) for adult and adolescent patients with ACABS. Twelve hundred twenty-nine patients entered the U.S. study, 698 with antral puncture; 569 patients entered the European study, all with antral puncture. Clinical response (cure or improvement) was determined 7 to 14 days and 3 to 5 weeks posttherapy. Microbiologic eradication rates were determined 10 to 30 days posttherapy in a subset of patients who underwent pre- and posttherapy sinus aspirate culture. Rates of adverse events and treatment discontinuations due to adverse events were examined. Cefdinir, given once or twice daily, was as effective clinically (approximately 90% cure rate) as amoxicillin-clavulanate given three times daily in the treatment of ACABS. Microbiologic eradication rates were also similar in the three groups. The major side effect was mild diarrhea, occurring in approximately 20% of each group. Cefdinir caused fewer adverse events requiring treatment discontinuation.
Pharmacokinetics of hyperimmune anti-human immunodeficiency virus immunoglobulin in persons with AIDS
Authors: Fletcher C V , Goodroad B K , Cummins L M , Henry K , Balfour H H , Rhame F S
Published: October 2018

Hyperimmune anti-human immunodeficiency virus immunoglobulin (HIVIG) is an intravenous immunoglobulin prepared from HIV-infected asymptomatic donors with a CD4 cell count greater than 400 cells/microl and a high titer of antibody to HIV-1 p24 protein. Twelve persons with AIDS received four doses of HMG (two at 50 mg/kg of body weight and then two at 200 mg/kg) every 28 days. Pharmacokinetics were evaluated by measurement of anti-p24 antibody. HIVIG was well tolerated, and all participants completed the study. Three subjects who were not receiving Pneumocystis carinii pneumonia (PCP) prophylaxis developed PCP. The mean value for HIVIG clearance was 3.02 ml/kg/day at 50 mg/kg and 3.65 ml/kg/day at 200 mg/kg (P = 0.027); the mean trough antibody titers (reciprocal units) were 1,442 and 4,428, respectively. This study indicates that high titers of anti-p24 antibody can be maintained with a monthly administration schedule of HIVIG and that short-term safety is acceptable. Comparisons to evaluate the therapeutic potential of HIVIG are justified.
Effect of severity of meningitis on fungicidal activity of flucytosine combined with fluconazole in a murine model of cryptococcal meningitis
Authors: Ding J C , Bauer M , Diamond D M , Leal M A , Johnson D , Williams B K , Thomas A M , Najvar L , Graybill J R , Larsen R A
Published: October 2018

We studied the effect of the severity of meningitis on the response to therapy with fluconazole and flucytosine in a murine model of cryptococcal meningitis. Meningitis was established by intracerebral injection of Cryptococcus neoformans. The severity of meningitis was varied by delaying the onset of treatment from 3 to 7 days. Animals were sacrificed after 14 days of treatment, and the numbers of C. neoformans per gram of brain tissue were quantified. The range of effective dose combinations of fluconazole and flucytosine became progressively reduced as the severity of meningitis increased. The magnitude of treatment effect, as measured by the numbers of CFU/gram of brain tissue, was also reduced with increasing severity of meningitis. In this model, as the severity of meningitis increases, higher doses of fluconazole are required to achieve equivalent levels of activity. The combination of fluconazole and flucytosine appears to have the most-potent antifungal effects. This is most readily observed in animals with more-severe meningitis.
In vitro activity of BAY 12-8039, a novel 8-methoxyquinolone, compared to activities of six fluoroquinolones against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis
Authors: Brueggemann A B , Kugler K C , Doern G V
Published: October 2018

The in vitro activity of a novel 8-methoxyquinolone, BAY 12-8039, against recent clinical isolates of Streptococcus pneumoniae (n = 404), Haemophilus influenzae (n = 330), and Moraxella catarrhalis (n = 250) was evaluated. Activity was compared to those of six other fluoroquinolones: ciprofloxacin, clinafloxacin, levofloxacin, ofloxacin, sparfloxacin and trovafloxacin. BAY 12-8039 and clinafloxacin had the highest levels of activity against S. pneumoniae, both with a MIC at which 90% of the isolates were inhibited (MIC90) of 0.06 microg/ml. Trovafloxacin and sparfloxacin were the next most active agents versus S. pneumoniae (MIC90s = 0.12 microg/ml). No differences in activity against penicillin-susceptible, -intermediate, or -resistant strains of S. pneumoniae were noted for any of the fluoroquinolones tested. MIC90s for the seven fluoroquinolones ranged from 0.008 to 0.06 microg/ml versus H. influenzae and from 0.008 to 0.12 microg/ml for M. catarrhalis. The MICs for two strains of S. pneumoniae and one strain of H. influenzae were noted to be higher than those for the general population of organisms for all of the fluoroquinolones tested. Finally, the activity of BAY 12-8039 versus S. pneumoniae was found to be diminished when MIC determinations were performed with incubation of agar dilution plates or broth microdilution trays in 5 to 7% CO2 versus ambient air.
In vitro activity of a new pneumocandin antifungal, L-743,872, against azole-susceptible and -resistant Candida species
Authors: Vazquez J A , Lynch M , Boikov D , Sobel J D
Published: October 2018

The in vitro activity of a new pneumocandin, L-743,872, was evaluated with 108 strains of Candida and compared with the activities of various antifungals. L-743,872 demonstrated the best activity against azole-susceptible and -resistant strains of C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, and C. kefyr and less activity against C. krusei, C. lusitaniae, and C. guilliermondii.
Ethambutol resistance in Mycobacterium tuberculosis: critical role of embB mutations
Authors: Sreevatsan S , Stockbauer K E , Pan X , Kreiswirth B N , Moghazeh S L , Jacobs W R , Telenti A , Musser J M
Published: October 2018

Ethambutol [(S,S')-2,2'-(ethylenediimino)di-1-butanol; EMB], is a first-line drug used to treat tuberculosis. To gain insight into the molecular basis of EMB resistance, we characterized the 10-kb embCAB locus in 16 EMB-resistant and 3 EMB-susceptible genetically distinct Mycobacterium tuberculosis strains from diverse localities by automated DNA sequencing and single-stranded conformation polymorphism analysis. All 19 organisms had virtually identical sequences for the entire 10-kb region. Eight EMB-resistant organisms had mutations located in codon 306 of embB that resulted in the replacement of the wild-type Met residue with Ile or Val. Automated sequence analysis of the 5' region (1,892 bp) of embB in an additional 69 EMB-resistant and 30 EMB-susceptible M. tuberculosis isolates from diverse geographic localities and representing 70 distinct IS6110 fingerprints confirmed the unique association of substitutions in amino acid residue 306 of EmbB with EMB resistance. Six other embB nucleotide substitutions resulting in four amino acid replacements were uniquely found in resistant strains. Sixty-nine percent of epidemiologically unassociated EMB-resistant organisms had an amino acid substitution not found in susceptible strains, and most (89%) replacements occurred at amino acid residue 306 of EmbB. For strains with the Met306Leu or Met306Val replacements EMB MICs were generally higher (40 microg/ml) than those for organisms with Met306Ile substitutions (20 microg/ml). The data are consistent with the idea that amino acid substitutions in EmbB alter the drug-protein interaction and thereby cause EMB resistance.
An extracellular factor regulating expression of the chromosomal aminoglycoside 2'-N-acetyltransferase of Providencia stuartii
Authors: Rather P N , Parojcic M M , Paradise M R
Published: October 2018

The chromosomal aac(2')-Ia gene in Providencia stuartii encodes a housekeeping 2'-N-acetyltransferase [AAC(2')-Ia] involved in the acetylation of peptidoglycan. In addition, the AAC(2')-Ia enzyme also acetylates and confers resistance to the clinically important aminoglycoside antibiotics gentamicin, tobramycin, and netilmicin. Expression of the aac(2')-Ia gene was found to be strongly influenced by cell density, with a sharp decrease in aac(2')-Ia mRNA accumulation as cells approached stationary phase. This decrease was mediated by the accumulation of an extracellular factor, designated AR (for acetyltransferase repressing)-factor. AR-factor was produced in both minimal and rich media and acted in a manner that was strongly dose dependent. The activity of AR-factor was also pH dependent, with optimal activity at pH 8.0 and above. Biochemical characterization of conditioned media from P. stuartii has shown that AR-factor is between 500 and 1,000 Da in molecular size and is heat stable. In addition, AR-factor was inactivated by a variety of proteases, suggesting that it may be a small peptide.
Cloning and sequencing of a novel gene (recG) that affects the quinolone susceptibility of Staphylococcus aureus
Authors: Niga T , Yoshida H , Hattori H , Nakamura S , Ito H
Published: October 2018

In a study of the quinolone resistance genes in Staphylococcus aureus, a recG homolog was cloned as a gene affecting quinolone susceptibility. Sequencing analysis revealed that the gene consists of 2,061 nucleotides and encodes a 686-amino-acid polypeptide, which shows 38, 39, and 50% amino acid identity with the RecGs of Escherichia coli, Haemophilus influenzae, and Streptococcus pneumoniae, respectively. Seven helicase motifs are well conserved in the gene product. A plasmid carrying the gene complemented a recG-deficient mutant of E. coli with respect to mitomycin hypersusceptibility, demonstrating that the gene product is functionally equivalent to E. coli RecG. These results indicate that the gene is the recG gene of S. aureus. S. aureus RCM101 (recG::Tn551), designated S. aureus 3f33, is four to eight times more susceptible to quinolones than the parent strain, RCM101. The transformation of strain 3f33 with a plasmid carrying the S. aureus recG gene made it as quinolone resistant as strain RCM101. These results suggest that the recG gene is involved in the repair of DNA damage resulting from quinolone treatment in S. aureus.
Treatment of murine disseminated candidiasis with L-743,872
Authors: Graybill J R , Najvar L K , Luther M F , Fothergill A W
Published: October 2018

L-743,872 (M991), which is a pneumocandin derivative, was evaluated in a mouse model of disseminated candidiasis caused by a fluconazole-resistant isolate of Candida albicans. In immunocompetent mice M991 prolonged survival at doses as low as 0.0125 mg/kg of body weight per day. In neutropenic mice 0.05 mg/kg was the lowest effective dose. M991 is a very potent drug for treatment of disseminated candidiasis.
Increased production of penicillin-binding protein 2, increased detection of other penicillin-binding proteins, and decreased coagulase activity associated with glycopeptide resistance in Staphylococcus aureus
Authors: Moreira B , Boyle-Vavra S , deJonge B L , Daum R S
Published: October 2018

The mechanism of glycopeptide resistance in the genus Staphylococcus is unknown. Since these antimicrobial compounds act by binding the peptidoglycan precursor terminus, the target of transglycosylase and transpeptidase enzymes, it was hypothesized that resistance might be mediated in Staphylococcus aureus by increased production or activity of these enzymes, commonly called penicillin-binding proteins (PBPs). To evaluate this possibility, glycopeptide-resistant mutants were prepared by passage of several clinical isolates of this species in nutrient broth containing successively increasing concentrations of the glycopeptide vancomycin or teicoplanin. Decreased coagulase activity and increased resistance to lysostaphin were uniformly present in the vancomycin-resistant mutants. Peptidoglycan cross-linking increased in one resistant isolate and decreased in two resistant isolates. The amounts of radioactive penicillin that bound to each PBP in susceptible and resistant strains were compared; PBP2 production was also evaluated by Western blotting. Increased penicillin labeling and production of PBP2 were found in all resistant derivatives selected by either vancomycin or teicoplanin. Moreover, the increase in PBP2 penicillin labeling occurred early in a series of vancomycin-selected derivatives and was strongly correlated (r > 0.9) with the increase in vancomycin and teicoplanin MIC. An increase in penicillin labeling also occurred, variably, in PBP1, PBP3, and/or PBP4. These data demonstrate a strong correlation between resistance to glycopeptides and increased PBP activity and/or production in S. aureus. Such an increase could allow PBPs to better compete with glycopeptides for the peptidoglycan precursor.
In vitro activities of terbinafine in combination with fluconazole and itraconazole against isolates of Candida albicans with reduced susceptibility to azoles
Authors: Barchiesi F , Falconi Di Francesco L , Scalise G
Published: October 2018

A checkerboard microdilution method was applied to study the in vitro interaction of terbinafine with either fluconazole and itraconazole against 30 strains of Candida albicans. Synergy was observed in 40% of the terbinafine-fluconazole interactions and in 43% of the terbinafine-itraconazole interactions, while antagonism was not observed. Even when only additivity was achieved, the combinations still showed beneficial effects since at least twofold reductions in the MICs of both drugs were found in 100% of the terbinafine-fluconazole interactions and in 76% of the terbinafine-itraconazole interactions.
Voriconazole (UK-109,496) inhibits the growth and alters the morphology of fluconazole-susceptible and -resistant Candida species
Authors: Belanger P , Nast C C , Fratti R , Sanati H , Ghannoum M
Published: October 2018

The effects of voriconazole on the growth, ultrastructure, and leakage of cytoplasmic materials of Candida species were investigated. MIC data showed that voriconazole was more active than fluconazole. Exposure of yeast to voriconazole caused growth inhibition, cell wall thinning, and cell membrane degradation. Neither cell collapse nor release of cytoplasmic materials was observed in the treated cells.
Comparison of single-dose oral grepafloxacin with cefixime for treatment of uncomplicated gonorrhea in men. The STD Study Group
Authors: Hook E W , McCormack W M , Martin D , Jones R B , Bean K , Maroli A N
Published: October 2018

In a randomized open study, 351 male patients with uncomplicated gonorrhea were given single oral doses of grepafloxacin (400 mg) or cefixime (400 mg). In the 299 microbiologically evaluable patients, urethral infections were cured in 99% (147 of 149) of those receiving grepafloxacin and 97% (145 of 150) of those given cefixime. Eradication rates for both regimens were 100% in the 16% (47 of 299) of participants who were infected with penicillin-resistant Neisseria gonorrhoeae and 97% in the 21% (62 of 299) of participants infected with tetracycline-resistant strains. Grepafloxacin is a well-tolerated alternative to cefixime for treatment of uncomplicated gonorrhea in males.
Saquinavir-mediated inhibition of human immunodeficiency virus (HIV) infection in SCID mice implanted with human fetal thymus and liver tissue: an in vivo model for evaluating the effect of drug therapy on HIV infection in lymphoid tissues
Authors: Pettoello-Mantovani M , Kollmann T R , Raker C , Kim A , Yurasov S , Tudor R , Wiltshire H , Goldstein H
Published: October 2018

Treatment with protease inhibitors alone or in combination with inhibitors of reverse transcriptase potently suppresses levels of human immunodeficiency virus (HIV) RNA in plasma and thereby may significantly delay the progression of HIV-mediated disease. To investigate the effect of treatment with the protease inhibitor saquinavir on HIV replication in the lymphoid tissues, we used a SCID-hu mouse model that we developed, in which human thymic and liver tissues (hu-thy/liv) were implanted under both kidney capsules in SCID mice (thy/liv-SCID-hu mice). These mice are populated in the periphery with large numbers of human T cells and develop disseminated HIV infection after intraimplant injection. thy/liv-SCID-hu mice with established HIV infection that were treated for 1 month with saquinavir had a significantly lower viral load present in the implanted hu-thy/liv and mouse spleen than did the untreated HIV-infected thy/liv-SCID-hu mice. To examine the capacity of acute treatment with saquinavir to prevent HIV infection, some thy/liv-SCID-hu mice were inoculated with HIV and then immediately started on saquinavir. Although treated mice had markedly lower viral loads in the thy/liv implants and spleens, HIV infection was not completely prevented. Thus, the effect of antiviral therapy on HIV infection in the major site of HIV replication, the lymphoid tissues, can be readily evaluated in our thy/liv-SCID-hu mice. These mice should prove to be a useful model for determining the in vivo effectiveness of different therapeutic interventions on acute and chronic HIV infection.
Effect of fluconazole on the steady-state pharmacokinetics of delavirdine in human immunodeficiency virus-positive patients
Authors: Borin M T , Cox S R , Herman B D , Carel B J , Anderson R D , Freimuth W W
Published: October 2018

Fluconazole, an inhibitor of certain human cytochrome P-450 isozymes, is used for the prevention and treatment of a broad range of fungal infections that predominantly affect immunocompromised individuals. This study evaluated the influence of fluconazole on the steady-state pharmacokinetics of delavirdine, a nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase, in 13 HIV-1-infected patients with CD4 counts ranging from 186 to 480/mm3. Both the control group (n = 5) and the fluconazole group (n = 8) received 300 mg of delavirdine mesylate every 8 h for 30 days; subjects in the fluconazole group took a 400-mg, once-daily dose of fluconazole on study days 16 to 30. Harvested plasma from serial blood samples collected on days 15, 16, and 30 were assayed for concentrations of delavirdine and its N-desalkyl metabolite by a reversed-phase high-pressure liquid chromatography (HPLC) method. Blood samples obtained on days 16 and 30 were also assayed for fluconazole by HPLC. Delavirdine mesylate alone and in combination with fluconazole was well tolerated. There were no significant differences (P > 0.16) in delavirdine pharmacokinetic parameters between treatment groups on day 15 or day 30. After coadministration of fluconazole and delavirdine mesylate for 2 weeks (day 30), no significant differences (P > 0.058) were observed in any delavirdine pharmacokinetic parameters relative to those after receiving delavirdine mesylate alone (day 15) after in the fluconazole group. Fluconazole pharmacokinetic parameters were similar to those previously reported for healthy volunteers and HIV-positive patients. On the basis of these findings, fluconazole and delavirdine mesylate may be taken concurrently without adjustment of the dose of either drug.
Safety, tolerance, and pharmacokinetics of amphotericin B lipid complex in children with hepatosplenic candidiasis
Authors: Walsh T J , Whitcomb P , Piscitelli S , Figg W D , Hill S , Chanock S J , Jarosinski P , Gupta R , Pizzo P A
Published: October 2018

The safety, tolerance, and pharmacokinetics of amphotericin B lipid complex (ABLC) were studied in a cohort of pediatric cancer patients. Six children with hepatosplenic candidiasis (HSC) received 2.5 mg of ABLC/kg of body weight/day for 6 weeks for a total dosage of 105 mg/kg. Mean serum creatinine (0.85 +/- 0.12 mg/dl at baseline) was stable at the end of therapy at 0.85 +/- 0.18 mg/dl and at 1-month follow-up at 0.72 +/- 0.12 mg/dl. There was no increase in hepatic transaminases. Mean plasma concentrations over the dosing interval (C(ave)) and area under the curve from 0 to 24 h (AUC(0-24h)) increased between the first and seventh doses but were similar between doses 7 and 42, suggesting that steady state was achieved by day 7 of therapy. Following the final (42nd) dose of ABLC, mean AUC(0-24h) was 11.9 +/- 2.6 microg h/ml, C(ave) was 0.50 +/- 0.11 microg/ml, maximum concentration of the drug in whole blood was 1.69 +/- 0.75 microg/ml, and clearance was 3.64 +/- 0.78 ml/min/kg. Response of hepatic and splenic lesions was monitored by serial computerized tomographic and magnetic resonance imaging scans. The five evaluable patients responded to ABLC with complete or partial resolution of physical findings and of lesions of HSC. During the course of ABLC infusions and follow-up, there was no progression of HSC, breakthrough fungemia, or posttherapy recurrence. Hepatic lesions continued to resolve after the completion of administration of ABLC. Thus, ABLC administered in multiple doses to children was safe, was characterized by a steady state attainable within 1 week of therapy, and was effective in treatment of HSC.