bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro and in vivo antibacterial activities of GV129606, a new broad-spectrum trinem
Authors: Di Modugno E , Broggio R , Erbetti I , Lowther J
Published: October 2018

GV129606 is a new parenteral trinem antibiotic belonging to the beta-lactam class. It combines broad-spectrum activity (against gram-negative and -positive bacteria, aerobes and anaerobes), with high potency and resistance to beta-lactamases. Comparative in vitro and in vivo antibacterial activities were determined for GV129606 against more than 400 recent clinical isolates (aerobes, including beta-lactamase producers, and anaerobes), using representative antibacterial agents (meropenem, piperacillin, ceftazidime, cefpirome, ciprofloxacin, and gentamicin for aerobes and metronidazole, cefoxitin, piperacillin, and clindamycin for anaerobes). Against methicillin-susceptible staphylococci and streptococci, GV129606 and meropenem were the most active of the drugs tested. GV129606 showed an MIC for 90% of strains tested (MIC90) ranging from < or =0.015 to 0.06 microg/ml against methicillin-susceptible staphylococci and Streptococcus sanguis, Streptococcus pyogenes, and Streptococcus agalactiae. Against penicillin-susceptible and -resistant Streptococcus pneumoniae isolates, GV129606, meropenem, and cefpirome showed MIC90s of < or =0.015 and 1 microg/ml, respectively. Meropenem was the most active compound against members of the family Enterobacteriaceae with MIC90s of < or =0.5 microg/ml. Against these species, GV129606 possessed activity superior to those of piperacillin, ceftazidime, cefpirome, and gentamicin, with MIC90s of < or =8 microg/ml, but its activity was two- to sixfold less than that of ciprofloxacin (with the exception of Proteus rettgeri and Providencia stuartii). Haemophilus spp., Moraxella catarrhalis, Neisseria gonorrhoeae, and Pseudomonas aeruginosa were also included in the spectrum of GV129606. GV129606 showed good antianaerobe activity, similar to metronidazole. It was stable against all clinically relevant beta-lactamases (similar to meropenem). The in vitro activity was confirmed in vivo against septicemia infections induced in mice by selected gram-positive and -negative bacteria with 50% effective doses (ED50s) of < or =0.05 and < or =0.5 mg/kg of body weight/dose, respectively. GV129606 was as effective as meropenem against septicemia in mice caused by ceftazidime-resistant Pseudomonas aeruginosa, exhibiting an ED50 of 0.33 mg/kg/dose.
Influence of erythromycin resistance, inoculum growth phase, and incubation time on assessment of the bactericidal activity of RP 59500 (quinupristin-dalfopristin) against vancomycin-resistant Enterococcus faecium
Authors: Caron F , Gold H S , Wennersten C B , Farris M G , Moellering R C , Eliopoulos G M
Published: October 2018

RP 59500, a mixture of two semisynthetic streptogramin antibiotics (quinupristin and dalfopristin), is one of a few investigational agents currently in clinical trials with inhibitory activity against multiple-drug-resistant strains of Enterococcus faecium. We evaluated the bactericidal activity of this antimicrobial against 30 recent clinical isolates of vancomycin-resistant E. faecium, including 23 erythromycin-resistant (MIC, >256 microg/ml) and 7 erythromycin-intermediate (MIC, 2 to 4 microg/ml) strains. All isolates were inhibited by RP 59500 at 0.25 to 1.0 microg/ml. The bactericidal activity of RP 59500 was markedly influenced by the erythromycin susceptibility of the strains and by several technical factors, such as inoculum growth phase and time of incubation of counting plates. As determined by time-kill methods, RP 59500 at a concentration of 2 or 8 microg/ml failed to kill erythromycin-resistant organisms under any conditions. Bactericidal activity was observed against all seven erythromycin-intermediate isolates when log-phase inocula were used and the cells were counted after 48 h of incubation (mean reductions in viable bacteria for RP 59500 at concentrations of 2 and 8 microg/ml, 3.45 and 3.50 log10 CFU/ml, respectively), but killing was diminished when the plates were examined at 72 h (mean killing, 3.06 and 2.95 log10, CFU/ml, respectively). No bactericidal activity was observed when stationary-phase cultures were used. On the basis of these data, we expect that bactericidal activity of RP 59500 against the multiple-drug-resistant E. faecium strains currently encountered would be distinctly uncommon.
Canadian Multicenter Susceptibility Study, with a focus on cephalosporins, from 15 Canadian medical centers. The Canadian Multicenter Study Group
Authors: Blondeau J M , Yaschuk Y
Published: October 2018

We have previously reported on the in vitro susceptibilities of 4,482 microorganisms to 10 antimicrobial agents tested as part of a Canadian multicenter study. We now report on the remaining 10 agents tested in that study. Of the cephalosporins reported here, ceftriaxone had the greatest activity (82 to 100% susceptible isolates) against Enterobacteriaceae, compared to ceftizoxime (78 to 100%) and cefoperazone (78 to 100%). Cefoperazone activity against Pseudomonas aeruginosa was 87%, compared to 92% for ticarcillin-clavulanate. All agents had 97% or greater activity against Staphylococcus aureus.
Single-dose pharmacokinetics of thalidomide in human immunodeficiency virus-infected patients
Authors: Piscitelli S C , Figg W D , Hahn B , Kelly G , Thomas S , Walker R E
Published: October 2018

The pharmacokinetics of thalidomide in nine human immunodeficiency virus-infected patients were studied. Single doses of thalidomide were well absorbed, with mean peak concentrations (+/- standard deviations) of 1.17 +/- 0.21 and 3.47 +/- 1.14 microg/ml in the 100- and 300-mg dosing groups, respectively, and the mean elimination half-life was approximately 6 h. Adverse effects were mild, with drowsiness being reported for seven of nine patients.
Activity of a new triazole, Sch 56592, compared with those of four other antifungal agents tested against clinical isolates of Candida spp. and Saccharomyces cerevisiae
Authors: Pfaller M A , Messer S , Jones R N
Published: October 2018

Sch 56592 is a new triazole agent with potent, broad-spectrum antifungal activity. The in vitro activities of Sch 56592, itraconazole, fluconazole, amphotericin B, and flucytosine (5-FC) against 404 clinical isolates of Candida spp. (382 isolates) and Saccharomyces cerevisiae (22 isolates) were investigated. In vitro susceptibility testing was performed by a broth microdilution method performed according to National Committee for Clinical Laboratory Standards guidelines. Overall, Sch 56592 was very active (MIC at which 90% of isolates are inhibited [MIC90], 0.5 microgram/ml) against these yeast isolates. Sch 56592 was most active against Candida tropicalis, Candida parapsilosis, candida lusitaniae, and Candida stellatoidea (MIC90, < or = 0.12 microgram/ml) and was least active against Candida glabrata (MIC90, 2.0 micrograms/ml). Sch 56592 was 2- to 32-fold more active than amphotericin B and 5-FC against all species except C. glabrata. By comparison with the other triazoles, Sch 56592 was equivalent to itraconazole and greater than or equal to eightfold more active than fluconazole. On the basis of these results, Sch 56592 has promising antifungal activity, and further in vitro and in vivo investigations are warranted.
Modeling of the change in CD4 lymphocyte counts in patients before and after administration of the human immunodeficiency virus protease inhibitor indinavir
Authors: Stein D S , Drusano G L
Published: October 2018

We investigated the relationships between changes in CD4 lymphocytes counts over 24 weeks after the initiation of therapy with indinavir at dosages of > or = 2.4 g/day (n = 15) in human immunodeficiency virus-positive patients and compared them to the baseline values. Starting CD4 count were linked to the time-weighted average CD4 cell count (return) through a nonlinear effect model. The diminution of destruction of CD4 cells after the initiation of indinavir therapy was estimated by fitting simultaneous differential equations to the data by using a linked lymph node (LN)-blood (BL) (two-compartment) system in which there is a constant rate of generation (R), first-order transfer rate constants (KLN-BL and KBL-LN) of compartment exchange, and first-order rate constants of CD4 destruction in the absence and presence of indinavir (KLN-OUT1 and KLN-OUT2). The half-life of CD4 lymphocytes was calculated from the rate constants by standard two-compartment methods. The CD4 lymphocyte counts at the start and return were linked in a sigmoid-Emax model were the maximal effect (Emax) was at 574.6 cells/microliters and 50% of the effect occurred at 157.1 cells/microliters (r2 = 0.94; P < 0.001). The mean +/- standard deviation (median) KLN-OUT2 was 0.574 +/- 0.202 (0.589), indicating that indinavir decrease the destruction of CD4 cells by circa 41 to 42%. The mean (median) CD4 half-life was 11.5 +/- 5.72 day (10.3 days). In multivariate analysis, KLN-OUT2 was significantly correlated with starting the CD4 cells count and the change in the CD4 cell count on therapy. The relationship between CD4 lymphocyte half-life and the starting CD4 lymphocyte count was hyperbolic, with a rapid increase in half-life as the CD4 count decreased. On the basis of the calculated half-life, the average production (destruction) of CD4 lymphocytes was approximately 3 x 10(9) cells/day, with an individual variation of 44-fold. These findings suggest that (i) the CD4 lymphocyte cell count at the start is significantly correlated to both the decrease in the destruction rate of CD4 cells and the degree of change in the CD4 lymphocytes on therapy, (ii) the lower the initial CD4 lymphocyte count, the higher the amount of CD4 lymphocyte turnover and the lower the ability of the immune system to increase absolute CD4 lymphocyte levels after viral suppression, consistent with a decreased regenerative capacity with progression of disease; and (iii) the increase in CD4 lymphocytes is likely secondary to the expansion of proliferating pool of cells since our determinations are based on 24 weeks of effect.
Transferable hyperproduction of TEM-1 beta-lactamase in Shigella flexneri due to a point mutation in the pribnow box
Authors: Siu L K , Ho P L , Yuen K Y , Wong S S , Chau P Y
Published: October 2018

TEM-1 hyperproduction in two ampicillin-sulbactam-resistant Shigella flexneri strains was studied. In both strains the blaTEM gene was encoded as a single copy on a large conjugatively transferable plasmid. A single G-->T transversion at position 1 of the -10 consensus sequence was identified to be the mechanism of TEM-1 hyperproduction.
Targeting of DNA gyrase in Streptococcus pneumoniae by sparfloxacin: selective targeting of gyrase or topoisomerase IV by quinolones
Authors: Pan X S , Fisher L M
Published: October 2018

gyrA and parC mutations have been identified inn Streptococcus pneumoniae mutants stepwise selected for resistance to sparfloxacin, an antipneumococcal fluoroquinolone. GyrA mutations (at the position equivalent to resistance hot spot Ser-83 in Escherichia coli GyrA) were found in all 17 first-step mutants examined and preceded DNA topoisomerase IV parC mutations (at Ser-79 or Glu-83), which appeared only in second-step mutants. The targeting of gyrase by sparfloxacin in S. pneumoniae but of topoisomerase IV by ciprofloxacin indicates that target preference can be altered by changes in quinolone structure.
Trovafloxacin, a new fluoroquinolone with potent activity against Streptococcus pneumoniae
Authors: Thomson K S , Chartrand S A , Sanders C C , Block S L
Published: October 2018

An in vitro study of the activity of 15 antibacterial agents against 202 recent pediatric isolates of Streptococcus pneumoniae from urban and rural Nebraska and rural Kentucky identified trovafloxacin, ofloxacin, clindamycin, and vancomycin as the most active agents and equally active against both penicillin-susceptible and--resistant strains. In contrast, six beta-lactams, three macrolides, and trimethoprim-sulfamethoxazole were less active overall, especially against penicillin-intermediate and--resistant strains. Trovafloxacin inhibited all strains at a concentration of < or = 0.25 micrograms/ml and was 8- to 16-fold more potent than ofloxacin or ciprofloxacin.
Characterization of the potent in vitro and in vivo antimalarial activities of ionophore compounds
Authors: Gumila C , Ancelin M L , Delort A M , Jeminet G , Vial H J
Published: October 2018

Large-scale in vitro screening of different types of ionophores previously pinpointed nine compounds that were very active and selective in vitro against Plasmodium falciparum; their in vitro and in vivo antimalarial effects were further studied. Addition of the ionophores to synchronized P. falciparum suspensions revealed that all P. falciparum stages were sensitive to the drugs. However, the schizont stages were three- to ninefold more sensitive, and 12 h was required for complete parasite clearance. Pretreatment of healthy erythrocytes with toxic doses of ionophores for 24 to 48 h showed that the activity was not due to an irreversible effect on the host erythrocyte. No preferential ionophore adsorption in infected or uninfected erythrocytes occurred. On the other hand, ionophore molecules strongly bound to serum proteins since increasing the serum concentration from 2 to 50% led to almost a 25-fold parallel increase in the ionophore 50% inhibitory concentration. Mice infected with the malaria parasites Plasmodium vinckei petteri or Plasmodium chabaudi were successfully treated with eight ionophores in a 4-day suppressive test. The 50% effective dose after intraperitoneal administration ranged from 0.4 to 4.1 mg/kg of body weight, and the therapeutic indices were about 5 for all ionophores except monensin A methyl ether, 5-bromo lasalocid A, and gramicidin D, whose therapeutic indices were 12, 18, and 344, respectively. These three compounds were found to be curative, with no recrudescence. Gramicidin D, which presented impressive antimalarial activity, requires parenteral administration, while 5-bromo lasalocid A has the major advantage of being active after oral administration. Overall, the acceptable levels of toxicity and the good in vivo therapeutic indices in the rodent model highlight the interesting potential of these ionophores for the treatment of malaria in higher animals.
Submicellar complexes may initiate the fungicidal effects of cationic amphiphilic compounds on Candida albicans
Authors: Ahlström B , Chelminska-Bertilsson M , Thompson R A , Edebo L
Published: October 2018

The killing of Candida albicans by a series of amphiphilic quaternary ammonium compounds (QACs) with different hydrocarbon chain lengths was closely related to the binding of the compounds to the cells and damage of the cell membranes. The membrane damage was measured as the level of release of the UV-absorbing material into the medium in which the cells were suspended and as the level of uptake of propidium iodide in individual cells by flow cytometry. It was shown that of the compounds tested, hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide [CTAB]) bound most efficiently. Tetradecyl betainate chloride (B14), tetradecanoylcholine bromide (C14), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB) followed and had declining degrees of binding efficiency. The proportion of CTAB bound was almost total at concentrations up to the critical micelle concentration (CMC) of the compound, whereas that of B14 was somewhat smaller. For the two remaining tetradecyl compounds (C14 and TTAB), still smaller proportions were bound at low concentrations, but the proportions rose disproportionally at increasing concentrations to a distinct maximum at concentrations of 0.2 to 0.5 times the CMC. We propose that interfacial micelle-like aggregates are formed at the cell surface as a step in the binding process. An analogous, but less conspicuous, maximum was seen for DTAB. Thus, great differences in the binding affinity of QACs with different hydrocarbon chains at different concentrations to C. albicans were observed. These differences were related to the CMC of the compound. In contrast, the binding of TTAB to Salmonella typhimurium 395 MS was almost total at low as well as high concentrations until saturation was attained, indicating fundamental differences between binding to the yeast and binding to gram-negative bacteria. The importance of lipid-type complexes or aggregates to the antifungal effect of membrane-active substances are discussed.
In vitro activities of voriconazole (UK-109,496) against fluconazole-susceptible and -resistant Candida albicans isolates from oral cavities of patients with human immunodeficiency virus infection
Authors: Ruhnke M , Schmidt-Westhausen A , Trautmann M
Published: October 2018

The susceptibility of Candida albicans to a new antifungal triazole, voriconazole (UK-109,496), was investigated in 105 isolates obtained from the oral cavities of patients with human immunodeficiency virus (HIV) infection to study this drug's activity against fluconazole-susceptible and -resistant isolates. MICs were determined by a broth microdilution technique according to document M27-T from the National Committee for Clinical Laboratory Standards and by using a broth microdilution technique and a synthetic high-resolution medium. These antifungal susceptibility testing methods showed high levels of agreement (93% for fluconazole and 86% for voriconazole). Data from in vitro studies showed that voriconazole has good activity against fluconazole-susceptible and -resistant C. albicans isolates; the MICs at which 90% of all isolates were inhibited were 0.19 to 0.39 microgram/ml. We found that for isolates for which fluconazole MICs were high, voriconazole MICs were proportionally higher than those for fluconazole-susceptible C.albicans (P < 0.001). Pretreatment isolates from six patients with fluconazole-refractory esophageal candidiasis were included in the study. For these isolates the MICs were < or = 0.39 microgram/ml, and all patients responded to voriconazole. These results suggest that voriconazole is effective even in the treatment of fluconazole-refractory esophageal candidiasis and should be studied further to determine its clinical relevance in patients with HIV infection.
In vitro susceptibilities of Bartonella henselae, B. quintana, B. elizabethae, Rickettsia rickettsii, R. conorii, R. akari, and R. prowazekii to macrolide antibiotics as determined by immunofluorescent-antibody analysis of infected Vero cell monolayers
Authors: Ives T J , Manzewitsch P , Regnery R L , Butts J D , Kebede M
Published: October 2018

The in vitro susceptibilities of Bartonella (Rochalimaea) henselae, B. quintana, B. elizabethae, Rickettsia akari, R. conorii, R. prowazekii, and R. rickettsii to different concentrations of azithromycin, clarithromycin, dirithromycin, erythromycin, and roxithromycin in Vero cell cultures were evaluated. Bartonella and Rickettsia spp. were allowed to initiate infection of the antibiotic-free Vero cell monolayers, which were maintained in 16-chamber microscope slides in the absence of antibiotics at 32 degrees C in a CO2-enriched atmosphere. The monolayers were then incubated for 3 h to allow for initial host cell intracellular penetration by infecting species. After inoculation, inocula were replaced and tested with media containing 12 different concentrations of each antibiotic in replicate (10 wells of each antibiotic dilution) for each species, and the monolayers were reincubated. Tetracycline served as the control. Growth status of Bartonella spp. and Rickettsia spp. was determined by evaluation of immunofluorescent staining bacilli. Five days later, when antibiotic-free, control-infected cell monolayers demonstrated significant fluorescence, media were removed for all cell monolayers, the monolayers were fixed, and all specimens were stained with standard indirect immunofluorescent antibody reagents. Fluorescent foci were enumerated by counting such foci on random fields visualized with an epifluorescence microscope. The extent of antibiotic-induced focus inhibition was recorded for each dilution of antibiotic and compared with that of an antibiotic-negative control. Effective antibiotic dilution endpoints for inhibition of Bartonella and Rickettsia proliferation, as judged by absence of increase of significant fluorescence (as compared with no-growth controls), were enumerated by determining the number of cell culture chambers at various antibiotic dilutions that were negative or positive for significant Bartonella- or Rickettsia-specific fluorescence. All of the macrolide agents tested were readily active against all three Bartonella organisms, and azithromycin, clarithromycin, and roxithromycin may have potential in the treatment of Rickettsia infections. Animal model-based clinical trials are warranted to define the specific treatment role of the newer macrolide antibiotics.
In vivo efficacy of trovafloxacin (CP-99,217), a new quinolone, in experimental intra-abdominal abscesses caused by Bacteroides fragilis and Escherichia coli
Authors: Thadepalli H , Reddy U , Chuah S K , Thadepalli F , Malilay C , Polzer R J , Hanna N , Esfandiari A , Brown P , Gollapudi S
Published: October 2018

The efficacy of trovafloxacin in treating Bacteroides fragilis and Escherichia coli infections was investigated and compared to the efficacy of combined clindamycin and gentamicin therapy in an experimental model of intra-abdominal abscesses in rats. Rats were treated with different doses of CP-116,517-27, a parenteral prodrug of trovafloxacin. Response to treatment was evaluated by mortality rate and elimination of infection (cure rate). Mortality in the control group was 85.4%, whereas in rats treated with trovafloxacin, it was close to 0%. The highest cure rate (89.3%) resulted from the administration of 40 mg of CP-116,517-27 per kg of body weight three times a day (TID) for 10 days (equivalent to 18.15 mg of active drug trovafloxacin per rat per day). The therapeutic response with trovafloxacin was comparable to that of a combination therapy of clindamycin (75 mg/kg) plus gentamicin (20 mg/kg) TID (cure rate, 74%; mortality rate, 5%). The measured peak levels of trovafloxacin in serum and abscess pus were 2.6 +/- 0.3 and 5.2 micrograms/ml, respectively. The tumor necrosis factor alpha levels in the untreated animals were high compared to those for rats treated with trovafloxacin or clindamycin plus gentamicin. These results demonstrate that trovafloxacin as a single agent appears to be as successful as clindamycin plus gentamicin in the treatment of experimental intra-abdominal abscesses in rats.
Effect of incorporation of cidofovir into DNA by human cytomegalovirus DNA polymerase on DNA elongation
Authors: Xiong X , Smith J L , Chen M S
Published: October 2018

Cidofovir (CDV) (HPMPC) has potent in vitro and in vivo activity against human cytomegalovirus (HCMV), CDV diphosphate (CDVpp), the putative antiviral metabolite of CDV, is an inhibitor and an alternate substrate of HCMV DNA polymerase. CDV is incorporated with the correct complementation to dGMP in the template, and the incorporated CDV at the primer end is not excised by the 3'-to-5' exonuclease activity of HCMV DNA polymerase. The incorporation of a CDV molecule causes a decrease in the rate of DNA elongation for the addition of the second natural nucleotide from the singly incorporated CDV molecule. The reduction in the rate of DNA (36-mer) synthesis from an 18-mer by one incorporated CDV is 31% that of the control. However, the fidelity of HCMV DNA polymerase is maintained for the addition of the nucleotides following a single incorporated CDV molecule. The rate of DNA synthesis by HCMV DNA polymerase is drastically decreased after the incorporation of two consecutive CDV molecules; the incorporation of a third consecutive CDV molecule is not detectable. Incorporation of two CDV molecules separated by either one or two deoxynucleoside monophosphates (dAMP, dGMP, or dTMP) also drastically decreases the rate of DNA chain elongation by HCMV DNA polymerase. The rate of DNA synthesis decreases by 90% when a template which contains one internally incorporated CDV molecule is used. The inhibition by CDVpp of DNA synthesis by HCMV DNA polymerase and the inability of HCMV DNA polymerase to excise incorporated CDV from DNA may account for the potent and long-lasting anti-CMV activity of CDV.
Analysis of the oxyR-ahpC region in isoniazid-resistant and -susceptible Mycobacterium tuberculosis complex organisms recovered from diseased humans and animals in diverse localities
Authors: Sreevatsan S , Pan X , Zhang Y , Deretic V , Musser J M
Published: October 2018

Automated DNA sequencing was used to analyze the oxyR-ahpC region in 229 Mycobacterium tuberculosis complex isolates recently recovered from diseased humans and animals. The entire 1,221-bp region was studied in 118 isolates, and 111 other isolates were sequenced for oxyR, ahpC, or the 105-bp oxyR-ahpC intergenic region. The sample included isoniazid (INH)-susceptible and -resistant organisms in which the katG gene and inhA locus had previously been sequenced in their entirety to identify polymorphisms. A total of 16 polymorphic sites was identified, including 5 located in oxyR, 2 in ahpC, and 9 in the 105-bp intergenic region. All polymorphic sites located in the intergenic region, and the two missense substitutions identified in ahpC, occurred in INH-resistant organisms. In contrast, there was no preferential association of polymorphisms in oxyR, a pseudogene, with INH-resistant organisms. Surprisingly, most INH-resistant strains with KatG codon 315 substitutions that substantially reduce catalase-peroxidase activity and confer high MICs of INH lacked alterations in the ahpC gene or oxyR-ahpC intervening region. Taken together, the data are consistent with the hypothesis that some polymorphisms located in the ahpC-oxyR intergenic region are selected for after reduction in catalase or peroxidase activity attributable to katG alterations arising with INH therapy. These mutations are uncommon in recently recovered clinically significant organisms, and hence, there is no strict association with INH-resistant patient isolates. The ahpC compensatory mutations are apparently uncommon because strains with a KatG null phenotype are relatively rare among epidemiologically independent INH-resistant organisms.
Which aminoglycoside or fluoroquinolone is more active against Mycobacterium tuberculosis in mice?
Authors: Lounis N , Ji B , Truffot-Pernot C , Grosset J
Published: October 2018

To identify the most active aminoglycoside or fluoroquinolone for the treatment of tuberculosis, the in vivo activities of four different aminoglycosides and three different fluoroquinolones were compared with that of isoniazid (INH) in a murine tuberculosis model. Mice were each inoculated intravenously with 2.3 x 10(7) CFU of Mycobacterium tuberculosis H37Rv. Treatment began the next day (D1) after inoculation and continued for 4 weeks, at the frequency of six times weekly with one of the following regimens: INH, 25 mg/kg; ofloxacin, 200 mg/kg; levofloxacin, 100 or 200 mg/kg; sparfloxacin (SPFX), 50 mg/kg; and streptomycin, kanamycin, amikacin (AMIKA), and isepamicin, all at 200 mg/kg. The dosages of the treatments were presumably equivalent to their clinically tolerated dosages. The severity of infection and effectiveness of the treatment were assessed by the survival rate, spleen weights, gross lung lesions, and the numbers of CFU in the spleens. The results indicate that INH is more bactericidal than any of the aminoglycosides or fluoroquinolones tested, that AMIKA is the most active aminoglycoside, and that SPFX at 50 mg/kg is far more bactericidal than the treatment with other fluoroquinolones.
Conversion of 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosine to cidofovir by an intracellular cyclic CMP phosphodiesterase
Authors: Mendel D B , Cihlar T , Moon K , Chen M S
Published: October 2018

Cidofovir (HPMPC) [1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]-cytosine] is an acyclic nucleotide analog with potent and selective activity against herpesviruses. The prodrug, cyclic HPMPC (cHPMPC) [1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl) methyl]cytosine], has antiviral activity similar to that of the parent compound but exhibits reduced toxicity in animal models. cHPMPC is converted to cidofovir by a cellular cyclic CMP phosphodiesterase (EC 3.1.4.37) which hydrolyzes a variety of substrates, including adenosine 3',5'-cyclic monophosphate (cAMP) and cytidine 3',5'-cyclic monophosphate (cCMP). The K(m) and Vmax values for hydrolysis of cHPMPC by cCMP phosphodiesterase purified from human liver are 250 microM and 0.66 nmol.min-1.unit-1, respectively. These values are similar to the K(m) and Vmax values for cAMP (23 microM and 1.16 nmol.min-1.unit-1, respectively) and cCMP (75 microM and 2.32 nmol.min-1.unit of enzyme-1, respectively). The catalytic efficiency (Vmax/K(m) ratio) of this enzyme for the cHPMPC substrate is only 10- to 20-fold lower than those for the natural cyclic nucleotides, indicating that cHPMPC is a viable intracellular substrate for the human enzyme. Kinetic analysis indicates that cHPMPC, cAMP, and cCMP are competitive with respect to each other and that they are hydrolyzed by the same enzyme. cHPMPC is hydrolyzed to cidofovir in all primary human cell systems tested, including those derived from target organs that might be infected in patients with human cytomegalovirus (HCMV) disease. Importantly, hydrolysis of cHPMPC is not diminished in cells infected with HCMV.
In vivo anti-influenza virus activity of a zinc finger peptide
Authors: Judd A K , Sanchez A , Bucher D J , Huffman J H , Bailey K , Sidwell R W
Published: October 2018

Matrix protein (M1) is a major structural protein of influenza virus, and it inhibits its own polymerase. A 19-amino-acid peptide, corresponding to a zinc finger region of the M1 sequence of influenza virus strain A/PR/8/34 (H1N1), centered around amino acids 148 to 166, was synthesized. This peptide, designated peptide 6, represents a zinc finger which includes a 7-amino-acid loop or finger and a 4-amino-acid tail at the carboxyl terminus, in addition to the 8 amino acids involved in the coordination of Zn. Three experiments were run to evaluate the activity of peptide 6 on infections induced in mice by influenza A/PR/8/34 and A/Victoria/3/75 (H3N2) viruses. Intranasal (i.n.) treatment of the H1N1 virus infection with 30 or 60 mg/kg of body weight/day, three times daily for 5 days, beginning 4 h pre-or 8 h post-virus exposure, was effective in preventing death, reducing the arterial oxygen decline, and inhibiting lung consolidation. Virus titers in the lungs determined on day 5 were reduced by up to 1.5 log10 in treated groups, but considerable variation in the titers of the recovered virus was seen. The H3N2 virus infection was treated i.n. with 30, 60, or 120 mg of peptide 6/kg/day by using the above-mentioned delayed initiation treatment schedule, and similar protection was seen, although lung virus titers were not reduced in the day-5 assay. Peptide 6 was well tolerated at doses up to 60 mg/kg/day. This zinc finger peptide may provide a new class of antivirals effective against influenza virus.
Serum pharmacology of amphotericin B applied in lipid emulsions
Authors: Heinemann V , Kähny B , Jehn U , Mühlbayer D , Debus A , Wachholz K , Bosse D , Kolb H J , Wilmanns W
Published: October 2018

Application of amphotericin B in lipid emulsions (AmB/L) reduced membrane toxicity in vitro and decreased amphotericin B-associated toxic side effects in vivo when compared to that of amphotericin B applied in 5% glucose (AmB/G). Therefore, a comparative analysis of the pharmacological parameters of AmB/L and AmB/G was performed. Thirteen patients were analyzed, and nine of these patients received a subsequent treatment with AmB/G and AmB/L. In patients in both treatment groups amphotericin B showed a biphasic elimination from serum, with a prolonged terminal half-life of approximately 27 h. Patients treated with AmB/L showed significantly lower peak concentrations (44.2%; P = 0.008) and correspondingly lower area under the drug concentration-time curve (AUC) values (64.3%; P = 0.015) compared to the values for the same patients treated with AmB/G at a dose range of 0.6 to 1.5 mg/kg of body weight. The enhanced clearance of AmB/L may be due to a faster initial elimination of amphotericin B-lipid aggregates by the reticuloendothelial system. Lower peak concentrations and AUC values in serum and a correspondingly faster deposition of AmB/L in tissues may at least partly explain the lower toxicity of AmB/L. A comparative pharmacokinetic analysis with data for a single patient treated with AmB/L demonstrated that hemodialysis did not significantly affect the disposition of amphotericin B.
Study of use of cefdinir versus cephalexin for treatment of skin infections in pediatric patients. The Cefdinir Pediatric Skin Infection Study Group
Authors: Tack K J , Keyserling C H , McCarty J , Hedrick J A
Published: October 2018

Three hundred ninety-four patients, aged 6 months to 12 years, entered a multicenter, randomized, controlled, investigator-blind study comparing cefdinir, 7 mg/kg of body weight twice a day, with cephalexin, 10 mg/kg four times a day, each given for 10 days. The most common infections treated were impetigo and secondary infection of preexisting dermatitis. The most common pathogens isolated were Staphylococcus aureus and Streptococcus pyogenes. Two hundred thirty-one patients were microbiologically evaluable. Microbiologic eradication rates were 164 of 165 pathogens (99.4%) in the cefdinir group and 152 of 156 pathogens (97.4%) in the cephalexin group (P = 0.14). Clinical cure rates were 116 of 118 patients (98.3%) in the cefdinir group and 106 of 113 patients (93.8%) in the cephalexin group (P = 0.056). Sixteen percent of cefdinir patients and 11% of cephalexin patients experienced adverse events (P = 0.11), the most common being diarrhea, which affected 8% of the cefdinir group and 4% of the cephalexin group. Cefdinir appears to be an effective and well-tolerated agent for the treatment of uncomplicated skin and skin structure infections in pediatric patients.
Human immunodeficiency virus type 1 reverse transcriptase genotype and drug susceptibility changes in infected individuals receiving dideoxyinosine monotherapy for 1 to 2 years
Authors: Winters M A , Shafer R W , Jellinger R A , Mamtora G , Gingeras T , Merigan T C
Published: October 2018

The genetic mechanisms of human immunodeficiency virus type 1 (HIV-1) resistance to dideoxyinosine (ddI) in vivo have been described based on data from primary HIV-1 isolates. To better define the spectrum of HIV-1 reverse transcriptase (RT) changes occurring during ddI therapy, we determined the genotype and ddI susceptibility of the RT gene of HIV RNA isolated from the plasma of 23 patients who had received 1 to 2 years (mean, 87 +/- 16 weeks) of ddI monotherapy. Population-based sequencing of plasma virus showed that 12 of 23 (52%) patients developed known ddI resistance mutations: L74V (7 patients), K65R (2 patients), L74V with M184V (3 patients), and L74V with K65R (1 patient). Five patients developed one or more known zidovudine resistance mutations (at codons 41, 67, 70, 215, and/or 219) during the study. Other amino acid substitutions were found, but only S68G and L210W occurred in more than one patient. Studies of sensitivity to ddI were performed on population-based recombinant-virus stocks generated by homologous recombination between a plasmid containing an HXB2 clone with the RT gene deleted and RT-PCR products of the RT genes from patients' plasma RNA. The sequences of the virus stocks produced by this procedure were typically identical to the sequence of the input PCR product from plasma RNA. Both an MT-2 cell-based culture assay and a cell-free virion-associated RT inhibition assay showed that viruses possessing an L74V and/or M184V mutation or a K65R mutation had reduced sensitivity to ddI. Viruses without these specific mutations had no change in sensitivity to ddI. The results presented here show that the spectrum of RT mutations in a population of patients on ddI monotherapy is more complex than previously described. The development of multiple mutational patterns, including those that confer resistance to other nucleoside analogs, highlights the complexity of using the currently available nucleoside analogs for antiretroviral therapy.
Characterization of Saccharomyces cerevisiae CYP51 and a CYP51 fusion protein with NADPH cytochrome P-450 oxidoreductase expressed in Escherichia coli
Authors: Venkateswarlu K , Kelly D E , Kelly S L
Published: October 2018

Saccharomyces cerevisiae CYP51, target of azole antifungal agents, and CYP51 fused with S. cerevisiae cytochrome P-450 oxidoreductase (FUS protein) were expressed in active forms in Escherichia coli by cloning into pET15b. The expression was monitored immunologically, catalytically, and by using reduced carbon monoxide difference and type II binding spectra. CYP51 and FUS enzymes were located in membranes and produced a Soret peak at 448 nm in the reduced CO difference spectrum. The cytochrome P-450 contents in the membrane fractions containing CYP51 and FUS proteins were 12.8 +/- 2.6 and 17.4 +/- 3.7 pmol/mg of protein, respectively. The NADPH cytochrome P-450 oxidoreductase (CPR) content was estimated to be 15.7 +/- 1.1 pmol/mg of protein in FUS membrane fractions. FUS protein catalyzed the demethylation of substrate at the 14alpha position, with a turnover number of 1.96 +/- 0.37 min(-1) in the presence of NADPH. No reductase activity was observed in membrane fractions containing CYP51, and therefore, CYP51 did not function catalytically in the presence of NADPH, but in the presence of an artificial electron donor, cumene hydroperoxide, activity was comparable to that of the FUS enzyme. Further support for a normal structure for the hemoproteins was obtained from type II binding spectra, in which the spectral response was saturated with an equimolar concentration of ketoconazole.
OXA-15, an extended-spectrum variant of OXA-2 beta-lactamase, isolated from a Pseudomonas aeruginosa strain
Authors: Danel F , Hall L M , Gur D , Livermore D M
Published: October 2018

Pseudomonas aeruginosa AH, isolated in Ankara, Turkey, was highly resistant to ceftazidime (MIC, 128 microg/ml) and produced a beta-lactamase that gave a doublet of bands at pIs 8.7 and 8.9. beta-Lactamase production was transferable to P. aeruginosa PU21 by conjugation and was determined by a ca. 450-kb plasmid, pMLH54. The transconjugant and Escherichia coli transformed with the cloned gene showed increased resistance to ceftazidime (especially) and to cefpirome, ceftazidime, ceftriaxone, moxalactam, and aztreonam, but not to carbapenems. Resistance was not reversed by clavulanic acid or tazobactam. Sequencing revealed that the beta-lactamase responsible for this resistance was identical to OXA-2 except that glycine replaced aspartate at position 150. Compared to OXA-2, the new enzyme, named OXA-15, had greater cephalosporinase activity, with increased relative hydrolysis rates for cephaloridine and cephalothin and, most dramatically, for ceftazidime. Cefotaxime and carbapenems remained stable to hydrolysis. Thus, as in the TEM, SHV, and OXA-10 (PSE-2) beta-lactamase families, a minor sequence change in OXA-2 gave a major extension of cephalosporinase activity and contingent resistance. The gene encoding the new beta-lactamase, bla(OXA-15), lay close to the highly conserved 3' end of an integron and had flanking sequences typical of an integron-associated gene cassette. Restriction mapping and partial sequence data indicated that pMLH54 carries an integron with three putative gene cassettes: bla(OXA-15) itself, aadB [coding aminoglycoside nucleotidyltransferase (2")-1a], and an uncharacterized cassette.
Enhanced resistance to Cryptococcus neoformans infection induced by chloroquine in a murine model of meningoencephalitis
Authors: Mazzolla R , Barluzzi R , Brozzetti A , Boelaert J R , Luna T , Saleppico S , Bistoni F , Blasi E
Published: October 2018

Although the pathogenesis of cerebral cryptococcosis is poorly understood, local immune cells, such as microglia and astrocytes, likely play a critical role in containing infection. Chloroquine (CQ) is a weak base that accumulates within acidic vacuoles and increases their pH. Consequently, proteolytic activity of lysosomal enzymes and intracellular iron release/availability are impaired, resulting in decreased availability of nutrients crucial to microorganism survival and growth in the host. We found that CQ enhances BV2 microglial-cell-mediated anticryptococcal activity in vitro. The phenomenon is (i) evident when both unopsonized and opsonized microorganisms are used and (ii) mimicked by NH4Cl, another weak base, and by bafilomycin A1, an inhibitor of vacuolar-type H+-ATPases. In vivo, intracerebral administration of CQ before lethal local challenge with Cryptococcus neoformans results in a significant augmentation of median survival time and a marked reduction of yeast growth in the brain and is associated with the enhancement of local interleukin 1beta (IL-1beta) and IL-6 mRNA transcripts. Overall, these results provide the first evidence that CQ enhances anticryptococcal host defenses.
Mechanism of copper-mediated inactivation of herpes simplex virus
Authors: Sagripanti J L , Routson L B , Bonifacino A C , Lytle C D
Published: October 2018

The inactivation of herpes simplex virus (HSV) by copper was enhanced by the following reducing agents at the indicated relative level: ascorbic acid > hydrogen peroxide > cysteine. Treatment of HSV-infected cells with combinations of Cu(II) and ascorbate completely inhibited virus plaque formation to below 0.006% of the infectious virus input, while it maintained 30% viability for the host mammalian cells. The logarithm of the surviving fraction of HSV mediated by 1 mg of Cu(II) per liter and 100 mg of reducing agent per liter followed a linear relationship with the reaction time, in which the kinetic rate constant for each reducing agent was -0.87 min(-1) (r = 0.93) for ascorbate, -0.10 min(-1) (r = 0.97) for hydrogen peroxide, and -0.04 min(-1) (r = 0.97) for cysteine. The protective effects of metal chelators and catalase, the lack of effect of superoxide dismutase, and the partial protection conferred by free-radical scavengers suggest that the mechanism of copper-mediated HSV inactivation is similar to that previously reported for copper-mediated DNA damage. The sensitivity exhibited by HSV to Cu(II) and reducing agents, particularly ascorbate, might be useful in the development of therapeutic antiviral agents.
Emergence of an inhibitor-resistant beta-lactamase (SHV-10) derived from an SHV-5 variant
Authors: Prinarakis E E , Miriagou V , Tzelepi E , Gazouli M , Tzouvelekis L S
Published: October 2018

An inhibitor-resistant beta-lactamase (SHV-10), derived from an SHV-5 variant (SHV-9), was found in an Escherichia coli clinical isolate. In SHV-10, Ser-130 was replaced by Gly. The enzyme partially retained its ability to hydrolyze penicillins, but its activity against cephalosporins was drastically reduced. A Ser-130-->Gly mutant of the prototype SHV-5, obtained by site-directed mutagenesis, had properties similar to those of SHV-10.
In vitro activity of a new semisynthetic echinocandin, LY-303366, against systemic isolates of Candida species, Cryptococcus neoformans, Blastomyces dermatitidis, and Aspergillus species
Authors: Zhanel G G , Karlowsky J A , Harding G A , Balko T V , Zelenitsky S A , Friesen M , Kabani A , Turik M , Hoban D J
Published: October 2018

The in vitro activities of LY-303366, a new semisynthetic echinocandin, and comparators amphotericin B, 5-fluorocytosine, fluconazole, and ketoconazole against 205 systemic isolates of Candida species, Cryptococcus neoformans, Blastomyces dermatitidis, and Aspergillus species were determined. LY-303366 had MICs of < or = 0.32 microg/ml for all Candida albicans (n = 99), Candida glabrata (n = 18), and Candida tropicalis (n = 10) isolates tested. LY-303366 was also active against Aspergillus species (minimum effective concentration at which 90% of the isolates are inhibited, 0.02 microg/ml) (n = 20), was less active against Candida parapsilosis (MIC at which 90% of the isolates are inhibited [MIC90], 5.12 microg/ml) (n = 10), and was inactive against C. neoformans (MIC90, >10.24 microg/ml) (n = 15) and B. dermatitidis (MIC90, 16 microg/ml) (n = 29).
Heterogeneous expression of glycopeptide resistance in enterococci associated with transfer of vanB
Authors: Hayden M K , Picken R N , Sahm D F
Published: October 2018

In mating experiments using a clinical strain that constitutively expresses vanB-encoded glycopeptide resistance, resistance transfer was detectable at a frequency of <10(-7) transconjugants/donor. Vancomycin MICs for transconjugants were 2- to 10-fold lower than those for the donor; both inducibly and constitutively resistant transconjugants were obtained. These findings demonstrate that the transfer of vanB among enterococci can be associated with substantial alterations in the level and control of glycopeptide resistance expression.
Antibacterial activity of BMS-180680, a new catechol-containing monobactam
Authors: Fung-Tomc J , Bush K , Minassian B , Kolek B , Flamm R , Gradelski E , Bonner D
Published: October 2018

The in vitro activities of a new catechol-containing monobactam, BMS-180680 (SQ 84,100), were compared to those of aztreonam, ceftazidime, imipenem, piperacillin-tazobactam, ciprofloxacin, amikacin, and trimethoprim-sulfamethoxazole. BMS-180680 was often the most active compound against many species of the family Enterobacteriaceae, with MICs at which 90% of the isolates were inhibited (MIC90s) of < or = 0.5 microg/ml for Escherichia coli, Klebsiella spp., Citrobacter diversus, Enterobacter aerogenes, Serratia marcescens, Proteus spp., and Providencia spp. BMS-180680 had moderate activities (MIC90s of 2 to 8 microg/ml) against Citrobacter freundii, Morganella morganii, Shigella spp., and non-E. aerogenes Enterobacter spp. BMS-180680 was the only antibiotic evaluated that was active against >90% of the Pseudomonas aeruginosa (MIC90, 0.25 microg/ml), Burkholderia cepacia, and Stenotrophomonas maltophilia (MIC90s, 1 microg/ml) strains tested. BMS-180680 was inactive against most strains of Pseudomonas fluorescens, Pseudomonas stutzeri, Pseudomonas diminuta, and Burkholderia pickettii. BMS-180680 was moderately active (MIC90s of 4 to 8 microg/ml) against Alcaligenes spp. and Acinetobacter lwoffii and less active (MIC90, 16 microg/ml) against Acinetobacter calcoaceticus-Acinetobacter baumanii complex. BMS-180680 lacked activity against gram-positive bacteria and anaerobic bacteria. Both tonB and cir fiu double mutants of E. coli had greatly decreased susceptibility to BMS-180680. Of the TEM, PSE, and chromosomal-encoded beta-lactamases tested, only the K1 enzyme hydrolyzed BMS-180680 to any measurable extent. Like aztreonam, BMS-180680 bound preferentially to penicillin-binding protein 3. The MICs of BMS-180680 were not influenced by the presence of hematin or 5% sheep blood in the test medium or with incubation in an atmosphere containing 5% CO2. BMS-180680 MICs obtained under strict anaerobic conditions were significantly higher than those obtained in ambient air.