Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 79
Filter
1.
Clin Microbiol Infect ; 11(3): 243-4, 2005 Mar.
Article in English | MEDLINE | ID: mdl-15715726

ABSTRACT

Increased use of colistin therapy for infections caused by Pseudomonas aeruginosa has indicated a need for a more robust microbiological assay technique. This report describes a quick and simple microbiological assay for quantifying levels of colistin sulphomethate in serum and urine samples from cystic fibrosis patients. The technique uses no specialised or costly equipment and is suitable for use in all routine diagnostic microbiology laboratories.


Subject(s)
Biological Assay/methods , Colistin/blood , Colistin/urine , Culture Media , Cystic Fibrosis , Drug Stability , Escherichia coli/drug effects , Humans , Sensitivity and Specificity , Temperature
2.
J Antimicrob Chemother ; 49(3): 535-9, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11864955

ABSTRACT

The in vitro potency of BAL 9141, a new pyrrolidinone cephalosporin, was tested against non-duplicate strains of anaerobic bacteria. The MIC(50) was 1 mg/L against Actinomyces species, Clostridium species, Gram-positive anaerobic cocci, Porphyromonas species, Fusobacterium species, Lactobacillus species, Prevotella species and Veillonella species. The MIC(50) was 16 mg/L for Bacteroides fragilis and other Bacteroides species. BAL 9141 was not active against cefoxitin-resistant Bacteroides fragilis.


Subject(s)
Bacteria, Anaerobic/drug effects , Cephalosporins/pharmacology , Lactams/pharmacology , Penicillins/pharmacology , Thienamycins/pharmacology , Bacteria, Anaerobic/isolation & purification , Drug Resistance, Bacterial
4.
J Antimicrob Chemother ; 48(5): 727-30, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11679564

ABSTRACT

Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) may account for treatment failure with vancomycin and act as a precursor of vancomycin-intermediate or -resistant S. aureus. The activity of vancomycin was assessed against vancomycinsusceptible, hVISA and VISA strains in a dilutional pharmacokinetic model. Over a 48 h period, total bacteria and cells with a vancomycin-intermediate phenotype were quantified. Total counts of hVISA were reduced by vancomycin in a similar way to a vancomycin-susceptible control. The vancomycin-intermediate sub-population was eradicated from the model within one dose interval. Exposure to low vancomycin concentrations did not result in an increase in the proportion of cells which were vancomycin intermediate. Short-term exposure of hVISA to vancomycin at gradient concentrations did not increase the proportion of cells with vancomycin-intermediate phenotype.


Subject(s)
Anti-Bacterial Agents/pharmacokinetics , Methicillin Resistance , Staphylococcus aureus/drug effects , Vancomycin/pharmacokinetics , Anti-Bacterial Agents/pharmacology , Colony Count, Microbial/methods , Humans , Methicillin Resistance/genetics , Microbial Sensitivity Tests , Vancomycin/pharmacology
5.
Antimicrob Agents Chemother ; 45(10): 2916-21, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11557490

ABSTRACT

The pharmacodynamics of gemifloxacin against Streptococcus pneumoniae were investigated in a dilutional pharmacodynamic model of infection. Dose fractionation was used to simulate concentrations of gemifloxacin in human serum associated with 640 mg every 48 h (one dose), 320 mg every 24 h (two doses), and 160 mg every 12 h (four doses). Five strains of S. pneumoniae for which MICs were 0.016, 0.06, 0.1, 0.16, and 0.24 mg/liter were used to assess the antibacterial effect of gemifloxacin. An inoculum of 10(7) to 10(8) CFU/ml was used, and each experiment was performed at least in triplicate. The pharmacodynamic parameters (area under the concentration-time curve [AUC]/MIC, maximum concentration of drug in serum [C(max)]/MIC, and the time that the serum drug concentration remains higher than the MIC [T > MIC]) were related to antibacterial effect as measured by the area under the bacterial-kill curve from 0 to 48 h (AUBKC(48)) using an inhibitory sigmoid E(max) model. Weighted least-squares regression was used to predict the effect of the pharmacodynamic parameters on AUBKC(48), and Cox proportional-hazards regression was used to predict the effect of the three pharmacodynamic parameters on the time needed to kill 99.9% of the starting inoculum (T99.9). There was a clear relationship between strain susceptibility and clearance from the model. The simulations (160 mg every 12 h) were associated with slower initial clearance than were the other simulations; in contrast, bacterial regrowth occurred with the 640-mg simulation when MICs were > or =0.1 mg/liter. The percentage coefficient of variance was 19% for AUBKC(48), and the inhibitory sigmoid E(max) model best fit the relationship between AUBKC(48) and AUC/MIC. C(max)/MIC and T > MIC fit less well. The maximum response occurred at an AUC/MIC of >300 to 400. In weighted least-squares regression analysis, there was no evidence that C(max)/MIC was predictive of AUBKC(48), but both AUC/MIC and T > MIC were. A repeat analysis using only data for which the T > MIC was >75% and for which hence regrowth was minimized indicated that AUC/MIC alone was predictive of AUBKC(48). Initial univariate analysis indicated that all three pharmacodynamic parameters were predictive of T99.9, but in the multivariate model only C(max)/MIC reached significance. These data indicate that gemifloxacin is an effective antipneumococcal agent and that AUC/MIC is the best predictor of antibacterial effect as measured by AUBKC(48). However, C(max)/MIC is the best predictor of speed of kill, as measured by T99.9. T > MIC also has a role in determining AUBKC(48), especially when the dose spacing is considerable. Once-daily dosing seems most suitable for gemifloxacin.


Subject(s)
Anti-Infective Agents/pharmacology , Fluoroquinolones , Naphthyridines/pharmacology , Streptococcus pneumoniae/drug effects , Colony Count, Microbial , Gemifloxacin , Humans , Microbial Sensitivity Tests
6.
J Antimicrob Chemother ; 46(1): 73-8, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10882692

ABSTRACT

A dilutional culture in vitro pharmacodynamic model of infection was used to assess the best measure of antibacterial effect for moxifloxacin at simulated human doses of 400 mg 24 hourly for 48 h. This was then related to two pharmacodynamic parameters, the drug area under curve: MIC ratio (AUC/MIC) and the length of time that the drug concentration remained above the MIC of the bacterium (T > MIC). Twenty-one bacterial strains (Streptococcus pneumoniae n = 6; Haemophilus influenzae n = 6; Moraxella catarrhalis n = 3; beta-haemolytic streptococci n = 3; Staphylococcus aureus n = 3; MIC range 0.06-3.6 mg/L) were tested in 69 individual simulations. The measures or parameters of antibacterial effect considered were log change in viable count in the initial inoculum at 12 h (triangle up12), 24 h (triangle up24), 36 h (triangle up36), 48 h (triangle up48), maximum reduction in count (triangle up(max)); time for bacterial counts to reduce by 100-fold from the initial density (T99) or 1,000-fold (T99.9); and area under the bacterial kill curve from 0 to 24 h (AUBKC(24)) or from 0 to 48 h (AUBKC(48)). triangle up12, triangle up24, triangle up36, triangle up48, triangle up(max), T99, T99.9 did not vary over the complete range of MICs; at high MICs, especially with Gram-positive bacteria the T99 and T99.9 values were >48 h while at low MICs, especially with Gram-negative bacteria, bacterial counts were reduced below the limit of detection with triangle up12, triangle up24, triangle up36, triangle up48 and triangle up(max) exceeding >6.5 log reduction. AUBKC(24) and AUBKC(48) varied more completely over the range of MICs and more importantly had the best within-strain reproducibility (median percentage coefficient of variation <15%). The relationship between the transformed AUBKC(24) and AUC/MIC could be described by a sigmoid Emax model but the relationship with T > MIC could not. Use of weighted least squares regression to examine the combined effect of AUC/MIC and T > MIC on AUBKC(24) indicated that AUC/MIC provided a good fit to the data (r(2) = 0.94) and adding T > MIC did not improve the model fit. Cox proportional hazards regression indicated that AUC/MIC was predictive of T99 and in a multivariate model although AUC/MIC predicted outcome after fitting AUC/MIC, T > MIC was not significant. AUBKC was thus shown to be the optimum measure of antibacterial effect to use in pharmacodynamic studies of moxifloxacin and AUC/MIC the best predictor of antibacterial effect as measured by AUBKC(24) or T99. These results are in good agreement with animal data on moxifloxacin pharmacodynamics and human data for some other fluoroquinolones.


Subject(s)
Anti-Infective Agents/pharmacology , Aza Compounds , Bacteria/drug effects , Fluoroquinolones , Quinolines , Animals , Area Under Curve , Microbial Sensitivity Tests , Moxifloxacin
7.
J Antimicrob Chemother ; 44(6): 761-6, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10590276

ABSTRACT

The serum concentrations associated with the oral administration of 400 mg moxifloxacin every 24 h over 48 h in man were simulated in an in-vitro dilutional, continuous bacterial culture model of infection. The initial inoculum was 5 x 10(7)-5 x 10(8) cfu/mL and all strains were tested on at least three occasions. Two strains of Staphylococcus aureus (one methicillin susceptible, the other resistant) with moxifloxacin MICs 0.14 mg/L and 0.06 mg/L and two strains of beta-haemolytic streptococci, Lancefield Group A, MIC 0. 16 mg/L and Group G, MIC 0.4 mg/L were used. In addition, two laboratory-generated mutants with raised moxifloxacin MICs were also employed: methicillin-sensitive S. aureus (MSSA) MIC 1.0 mg/L and Group A streptococcus MIC 1.8 mg/L. The antibacterial effect of moxifloxacin was judged by changes in viable count over time, and the area under the bacterial-kill curve (AUBKC) after 24 and 48 h. For S. aureus MIC 0.14 mg/L the AUBKC(24) (log cfu/mL.h) was 77.8 +/- 4.6 and AUBKC(48) 92.0 +/- 6.9. For its mutant, moxifloxacin MIC 1.0 mg/L, the AUBKC(24) was 116.1 +/- 15.6 and AUBKC(48) 211.9 +/- 23.1, indicating decreased killing. AUBKC(24) and AUBKC(48) values of 110.7 +/- 10.3 and 130.9 +/- 21.3, respectively, were noted for the MRSA strain. The Group A streptococcus, MIC 0.16 mg/L, had an AUBKC(24) of 91.4 +/- 19.4 and AUBKC(48) of 157.0 +/- 70.9. The mutant, MIC 1.8 mg/L, had an AUBKC(24) of 127.0 +/- 1.9 and AUBKC(48) of 205.1 +/- 6.4. Despite a lower MIC (0.4 mg/L) the single strain of Group G streptococcus tested was killed poorly, AUBKC(24) 139.9 +/- 3.6 and AUBKC(48) 252.3 +/- 18.6. The pharmacodynamic parameters AUC/MIC, T > MIC, (AUC > MIC)/MIC (AUC = area under the curve, T = time) and WAUC ((AUC/MIC) (T > MIC/100)) (WAUC = weighted area under the curve) were related to AUBKC(24) and AUBKC(48) using an inhibitory sigmoid E(max) model. T > MIC was poorly related to AUBKC (r = 0.36) while AUC/MIC, (AUC > MIC)/MIC and WAUC were strongly related to AUBKC(24) (r = 0.75-0.79) and AUBKC(48) (r = 0.78-0.84). The maximum antibacterial effect was achieved with an AUC/MIC ratio of 150-200. AUC-related pharmacodynamic parameters predicted antibacterial effect better than T > MIC.


Subject(s)
Anti-Infective Agents/pharmacology , Aza Compounds , Fluoroquinolones , Quinolines , Staphylococcus aureus/drug effects , Streptococcus pyogenes/drug effects , Streptococcus/drug effects , Anti-Infective Agents/administration & dosage , Anti-Infective Agents/pharmacokinetics , Colony Count, Microbial , Culture Media , Humans , Microbial Sensitivity Tests , Moxifloxacin , Staphylococcus aureus/growth & development , Streptococcus/growth & development , Streptococcus pyogenes/growth & development
8.
J Antimicrob Chemother ; 44(4): 445-53, 1999 Oct.
Article in English | MEDLINE | ID: mdl-10588304

ABSTRACT

The in-vitro activity of HMR 3647 and seven comparators (azithromycin, clarithromycin, erythromycin A, roxithromycin, penicillin G, ciprofloxacin and levofloxacin) were tested against 207 Streptococcus pneumoniae and 200 beta-haemolytic streptococci. Ten comparators (azithromycin, clarithromycin, erythromycin A, roxithromycin, ampicillin, co-amoxiclav, cefuroxime, cefotaxime, ciprofloxacin and levofloxacin) were tested against 143 Haemophilus influenzae and 58 Moraxella catarrhalis. The MIC50 of HMR 3647 for S. pneumoniae was < or =0.008 mg/L, less than that for the macrolides or quinolones tested. Pneumococci with an erythromycin A MIC of 0.06 mg/L (n = 23) had an MIC50 of HMR 3647 < or =0.008 mg/L, whereas isolates with an erythromycin A MIC > or =1 mg/L (n = 34) had an MIC50 of HMR 3647 of 0.03 mg/L, a four-fold increase. In contrast, the difference in macrolide MIC50s for the two groups was > or =64-fold. The MIC50s foro beta-haemolytic streptococci, classified by Lancefield group, were in the range 0.015 to 0.06 mg/L for HMR 3647. H. influenzae were categorized into three groups according to cefuroxime MIC: <1 mg/L (n = 72); 2-4 mg/L (n = 29); and >4 mg/L (n = 42). The MIC50 of HMR 3647 increased two-fold with increasing cefuroxime MICs; beta-lactam MICs increased much more markedly. The MIC50 of HMR 3647 for M. catarrhalis was 0.03 mg/L. HMR 3647 has good activity against respiratory tract pathogens but in-vitro susceptibility is affected by erythromycin A susceptibility in S. pneumoniae and beta-haemolytic streptococci.


Subject(s)
Anti-Bacterial Agents/pharmacology , Haemophilus influenzae/drug effects , Ketolides , Macrolides , Moraxella catarrhalis/drug effects , Streptococcus pneumoniae/drug effects , Streptococcus/drug effects , Drug Resistance, Microbial , Humans , Microbial Sensitivity Tests
9.
J Antimicrob Chemother ; 44(5): 661-7, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10552983

ABSTRACT

The pharmacodynamics of ciprofloxacin were explored in an in-vitro continuous bacterial culture model of infection, by simulating two oral dosing regimens; 0.5 g 12-hourly (bd) and 1 g 24-hourly (od). Three strains of Escherichia coli (ciprofloxacin MICs 0.03, 0.5 and 2 mg/L); two strains of Pseudomonas aeruginosa (MICs 0.09 and 1.5 mg/L), two strains of Staphylococcus aureus (MICs 0.12 and 1 mg/L) and two strains of Streptococcus pneumoniae (MICs 0.5 and 2 mg/L) were used. Three pharmacodynamic parameters, T > MIC, C(max)/MIC and AUC/MIC (T = time, C(max) = peak serum concentration, AUC = area under the curve), were compared with area under the bacterial-kill curve (AUBKC) (after transformation of the AUBKC) using a simple E(max) or sigmoidal E(max) model. AUBKC was taken to be the main antibacterial effect measure. The models were compared by inspection of residuals and Akaike information criterion. E(max) models adequately described the relationship between AUC/MIC and AUBKC and between C(max)/MIC and AUBKC, but not between T> MIC and AUBKC. All three pharmacodynamic parameters are related to each other but multiple regression analysis indicated that AUC/MIC was the best individual predictor of AUBKC. Despite this, comparison of od and bd regimens indicates some advantage to od in terms of early antibacterial effect. Serum concentration-time curve shape has some importance in determining antibacterial effect. These data indicate that for ciprofloxacin AUC/MIC ratio is not the sole determinant of antibacterial effect.


Subject(s)
Anti-Infective Agents/administration & dosage , Anti-Infective Agents/pharmacology , Bacteria/drug effects , Ciprofloxacin/administration & dosage , Ciprofloxacin/pharmacology , Area Under Curve , Bacterial Infections/microbiology , Escherichia coli/drug effects , Escherichia coli/growth & development , Humans , Microbial Sensitivity Tests , Models, Biological , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development , Streptococcus pneumoniae/drug effects , Streptococcus pneumoniae/growth & development
10.
Antimicrob Agents Chemother ; 43(7): 1560-4, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10390203

ABSTRACT

The antibacterial effect of moxifloxacin was studied by using an in vitro pharmacodynamic model of infection with dosing simulations of 400 mg every 24 h for 48 h. Streptococcus pneumoniae was tested by using four wild-type strains for which the moxifloxacin MICs were 0. 008, 0.12, 0.14, and 3.6 mg/liter. In addition, two isogenic mutants, generated from the strains for which the moxifloxacin MICs were /=1.0 mg/liter, little killing occurred over 48 h. A sigmoid dose-response model indicated that the area under the curve/MIC ratio was strongly related to the log change in viable count at 24 and 48 h and to the AUBKC. These data indicate that moxifloxacin may have a role in management of S. pneumoniae infection.


Subject(s)
Anti-Infective Agents/pharmacology , Aza Compounds , Fluoroquinolones , Quinolines , Streptococcus pneumoniae/drug effects , Anti-Infective Agents/pharmacokinetics , Dose-Response Relationship, Drug , Drug Administration Schedule , Microbial Sensitivity Tests , Moxifloxacin
11.
J Antimicrob Chemother ; 43(3): 345-9, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10223589

ABSTRACT

Ciprofloxacin has a four-fold greater in-vitro activity than levofloxacin against Pseudomonas aeruginosa, but levofloxacin has a four-fold higher area under the serum concentration-time curve (AUC) for an equivalent dose. It has been proposed that the AUC/MIC ratio is a general predictor of antibacterial efficacy for quinolones. Using an in-vitro kill curve technique, performed in quadruplicate, with nine antibiotic concentrations and three strains of P. aeruginosa with varying quinolone susceptibility, we constructed sigmoidal dose-response curves for AUC(0-6.5)/MIC and area under the bacterial kill curve (AUBKC) or AUC(0-24)/MIC and log change in viable count at 24 h (delta24). For levofloxacin the log AUC(0-6.5)/MIC ratio to produce 50% of the maximal effect was 0.74 +/- 0.13 (r2 = 0.9435) for levofloxacin and 0.82 +/- 0.06 (r2 = 0.7935) for ciprofloxacin. The log AUC(0-24)/MIC ratio to produce 50% maximal effect was 1.58 +/- 0.13 (r2 = 0.7788) for levofloxacin and 1.37 +/- 0.12 (r2 = 0.7207) for ciprofloxacin. An AUC(0-24)/MIC ratio of 125 produced 85.4% of the maximal response with levofloxacin and 81.5% with ciprofloxacin. These data suggest that levofloxacin and ciprofloxacin have equivalent activity against P. aeruginosa at equivalent AUC/MIC ratios.


Subject(s)
Anti-Infective Agents/pharmacology , Ciprofloxacin/pharmacology , Levofloxacin , Ofloxacin/pharmacology , Pseudomonas aeruginosa/drug effects , Dose-Response Relationship, Drug , Microbial Sensitivity Tests
12.
J Antimicrob Chemother ; 42(4): 461-7, 1998 Oct.
Article in English | MEDLINE | ID: mdl-9818744

ABSTRACT

An in-vitro pharmacokinetic model was used to study the antibacterial activity of meropenem. Strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to meropenem concentrations likely to be produced in an adult by rapid iv infusion of 3 g once a day (q24h regimen), 1.5 g twice a day (ql2h regimen) or 1 g three times a day (q8h regimen). Each of these three dosing regimens produced a rapid reduction in viable bacterial count over the first 16 h after dosing. There were no differences in the pattern of reduction in viable count with the q24h, q12h or q8h regimens with any of the three bacterial strains tested over the first 16 h. However, reduction in viable counts was poorer at 24 h with the q24h than q12h or q8h regimens. A simulation lasting 48 h of the q24h dosing regimen indicated a reduction in bacterial count below the limit of detection from the model with E. coli but not with P. aeruginosa or S. aureus. The time for which the meropenem concentration was higher than the MIC for the bacteria correlated best with the reduction in viable bacterial count at 24 h. The AUC for the bacterial time-kill curve, which may be a better measure of antibacterial efficacy, was not related to the length of time for which the concentration was above the MIC or the peak concentration/MIC ratio. The antibacterial effect of the conventional q8h dosing simulation was indistinguishable from that given by the q12h simulation, and both the q8h and q12h regimens offered minor advantages over a q24h regimen. Dosing of meropenem 12 hourly or 24 hourly in humans should be investigated.


Subject(s)
Thienamycins/pharmacology , Adult , Area Under Curve , Colony Count, Microbial , Computer Simulation , Drug Administration Schedule , Escherichia coli/drug effects , Escherichia coli/isolation & purification , Humans , Meropenem , Microbial Sensitivity Tests , Models, Biological , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/isolation & purification , Staphylococcus aureus/drug effects , Staphylococcus aureus/isolation & purification , Thienamycins/administration & dosage , Thienamycins/pharmacokinetics , Time Factors
13.
J Antimicrob Chemother ; 42(2): 161-9, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9738833

ABSTRACT

The majority of clinical microbiology laboratories in the UK use comparative disc diffusion methods based on the Stokes' method to determine antibiotic susceptibility. The technical validity of the results obtained from the modified Stokes' method of disc testing and how they relate to MIC data are not known. We studied susceptibility testing using a modified Stokes' disc diffusion method for a wide range of clinical isolates against which MICs had been determined by collaborators not involved with the disc testing evaluation. Results indicated that for 1301 organism-antibiotic combinations the number of major errors (where resistant strains were reported as sensitive) was 21/468 (4.4%) and the number of minor errors (where sensitive strains were reported as resistant) was 14/713 (1.9%) using ciprofloxacin breakpoints of 0.5 and 2 mg/L. There was good correlation between the disc susceptibility test and the MIC for 119 isolates of Enterobacteriaceae tested with the exception of Serratia spp. Excluding Serratia spp. the number of major errors for Enterobacteriaceae was 1/200 (0.5%). Data revealed 2/25 (8%) major errors for Pseudomonas aeruginosa and 1/45 (2.2%) for Acinetobacter spp. Haemophilus influenzae showed a number of unexpected categorization errors. The modified Stokes' method performed accurately for Staphylococcus aureus and coagulase-negative staphylococci when tested for susceptibility to gentamicin, erythromycin, teicoplanin and vancomycin. No major errors were reported for Streptococcus pneumoniae and beta-haemolytic streptococci. Problems occurred with the detection of antibiotic resistance in Enterococcus spp. Major errors were seen for ampicillin (2/12 strains), teicoplanin (5/6 strains) and vancomycin (5/13 strains) using a 30 microg disc but only 1/13 strains using a 5 microg disc. Overall, from our data, the modified Stokes' disc diffusion antibiotic susceptibility test showed an unacceptable number of major errors but an acceptable number of minor errors.


Subject(s)
Microbial Sensitivity Tests/methods , Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Evaluation Studies as Topic
15.
Antimicrob Agents Chemother ; 42(2): 419-24, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9527797

ABSTRACT

The in vitro activities of Y-688, a new 7-substituted fluoroquinolone derivative, against 317 nonduplicate anaerobic isolates were determined. Eighty-five percent of the Bacteroides fragilis group (n = 89) were inhibited by < or = 2 mg of Y-688 per liter, while 78, 100, 89, and 98% of gram-negative bacilli (n = 135), gram-positive cocci (n = 59), and non-spore-forming (n = 58) and spore-forming (n = 51) gram-positive bacilli, respectively, were inhibited by < or = 1 mg of Y-688 per liter.


Subject(s)
Anti-Infective Agents/pharmacology , Bacteria, Anaerobic/drug effects , Fluoroquinolones , Anti-Infective Agents/chemistry , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests
16.
J Antimicrob Chemother ; 40(4): 503-9, 1997 Oct.
Article in English | MEDLINE | ID: mdl-9372419

ABSTRACT

The in-vitro activity of a new 8-methoxy-quinolone, Bay 12-8039, was assessed against 218 anaerobic bacteria. Ninety-eight per cent of strains belonging to the Bacteroides fragilis group (n = 65) were inhibited by < or = 2 mg/L of Bay 12-8039 whereas 97%, 94%, 94% and 100%, respectively, of Gram-negative bacilli (n = 93), non-sporing Gram-positive bacilli (n = 36), endospore-forming Gram-positive bacilli (n = 34) and Gram-positive cocci (n = 45) were also inhibited by < or = 2 mg/L. Eighty-three per cent of all anaerobes tested were inhibited by < or = 1 mg/L Bay 12-8039 and 99.5% by < or = 4 mg/L. When compared with ciprofloxacin, clinafloxacin, ofloxacin and trovafloxacin, Bay 12-8039 was more active than ciprofloxacin and ofloxacin, equipotent to trovafloxacin but not as active as clinafloxacin.


Subject(s)
Anti-Infective Agents/pharmacology , Aza Compounds , Bacteria, Anaerobic/drug effects , Fluoroquinolones , Quinolines , Quinolones/pharmacology , Microbial Sensitivity Tests , Moxifloxacin
18.
J Antimicrob Chemother ; 39(3): 355-61, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9096185

ABSTRACT

The Innofluor fluorescence polarization immunoassay (FPIA) kits for gentamicin, tobramycin, amikacin and vancomycin were evaluated on an Abbott TDX analyser. Intra-assay reproducibility was excellent with a coefficient of variation of <3% for all analytes. The coefficient of variation for inter-assay reproducibility was usually <5%. Assay linearity was good and standard curve stability was seen with kits of the same batch for at least 32 days. Using clinical samples, the results obtained with the Innofluor FPIA reagents correlated well with those obtained using Abbott FPIA reagents, but Innofluor gentamicin and amikacin results were slightly higher than Abbott results (P < 0.001). Results of UK NEQAS returns showed acceptable accuracy for the Innofluor kits, but mean Innofluor gentamicin returns were 4% higher (P = 0.001) and mean vancomycin returns were 5% lower (P = 0.001) than overall mean returns. Innofluor and Abbott vancomycin assay reagents showed similar cross-reactivity to degraded vancomycin.


Subject(s)
Amikacin/blood , Anti-Bacterial Agents/blood , Fluorescence Polarization Immunoassay/methods , Gentamicins/blood , Tobramycin/blood , Vancomycin/blood , Cross Reactions , Humans , Reproducibility of Results
19.
Tree Physiol ; 17(2): 97-103, 1997 Feb.
Article in English | MEDLINE | ID: mdl-14759879

ABSTRACT

Effects of flurprimidol on plant water relations and leaf gas exchange were investigated in one-year-old white ash (Fraxinus americana L.) seedlings subjected to soil water deficits. Flurprimidol (20 mg kg(-1) of soil equivalent) was applied to the soil surface of pot-grown seedlings after shoot growth was completed. Two months after flurprimidol application, water was withheld from one-half of the seedlings. Leaf water relations and gas exchange parameters were measured 5, 7, 10, 14, 18 and 22 days after withholding water. Under both irrigated and nonirrigated conditions, flurprimidol treatment resulted in reduced net CO(2) assimilation rate and transpirational water loss of seedlings as a result of decreased stomatal conductance. Consequently, flurprimidol-treated seedlings had higher leaf water potential and relative water content than untreated seedlings. Nonirrigated flurprimidol-treated seedlings also had greater turgor and sap osmolality and lower osmotic potential at full turgor than seedlings in the other treatments, indicating that flurprimidol increased osmotic adjustment. Under water-stress conditions, water use efficiency was lower and gas exchange efficiency was higher in flurprimidol-treated seedlings than in untreated seedlings, suggesting that flurprimidol treatment enhances survival of plants subjected to soil water deficits.

20.
J Antimicrob Chemother ; 38(6): 1055-60, 1996 Dec.
Article in English | MEDLINE | ID: mdl-9023653

ABSTRACT

The effect of increasing meropenem concentrations up to 250 mg/L, as might occur if 3 g was given as a single daily intravenous dose, was investigated in terms of bactericidal activity, post antibiotic effect (PAE) and modified controlled effective regrowth time (mCERT). Increasing the meropenem concentration above 50 mg/L did not result in increased bacterial killing, while concentrations over 75 mg/L did not result in longer PAE or mCERT.


Subject(s)
Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/growth & development , Gram-Positive Bacteria/drug effects , Gram-Positive Bacteria/growth & development , Thienamycins/pharmacology , Enterobacter/drug effects , Enterobacter/growth & development , Escherichia coli/drug effects , Escherichia coli/growth & development , Kinetics , Klebsiella/drug effects , Klebsiella/growth & development , Meropenem , Microbial Sensitivity Tests , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development
SELECTION OF CITATIONS
SEARCH DETAIL
...