Concentrations in plasma, epithelial lining fluid, alveolar macrophages and bronchial mucosa after a single intravenous dose of 1.6 mg/kg of iclaprim (AR-100) in healthy men.

OBJECTIVES: A validated microbiological assay was used to measure concentrations of iclaprim (AR-100) in plasma, bronchial mucosa (BM), alveolar macrophages (AM) and epithelial lining fluid (ELF) after a single 1.6 mg/kg intravenous 60 min iv infusion of iclaprim. METHODS: Male volunteers were randomly allocated to three nominal sampling time intervals 1-2 h (Group A), 3-4 h (Group B) and 5.5-7.0 h (Group C) after the start of the drug infusion. RESULTS: Mean iclaprim concentrations in plasma, BM, AM and ELF, respectively, were for Group A 0.59 mg/L (SD 0.18), 0.51 mg/kg (SD 0.17), 24.51 mg/L (SD 21.22) and 12.61 mg/L (SD 7.33); Group B 0.24 mg/L (SD 0.05), 0.35 mg/kg (SD 0.17), 7.16 mg/L (SD 1.91) and 6.38 mg/L (SD 5.17); and Group C 0.14 mg/L (SD 0.05), no detectable level in BM, 5.28 mg/L (SD 2.30) and 2.66 mg/L (SD 2.08). CONCLUSIONS: Iclaprim concentrations in ELF and AM exceeded the MIC(90) for penicillin-susceptible Streptococcus pneumoniae (MIC90 0.06 mg/L), penicillin-intermediate S. pneumoniae (MIC90 2 mg/L), penicillin-resistant S. pneumoniae (MIC90 4 mg/L) for 7, 7 and 4 h, respectively, and Chlamydia pneumoniae (MIC90 0.5 mg/L) for 7 h. Mean iclaprim concentrations in ELF exceeded the MIC90 for Haemophilus influenzae (MIC90 4 mg/L) and Moraxella catarrhalis (MIC90 8 mg/L) for up to 4 and 2 h, respectively; in AM the MIC90 was exceeded for up to 7 h. Furthermore, the MIC90 for methicillin-resistant Staphylococcus aureus of 0.12 mg/L was exceeded at all sites for up to 7 h. These data suggest that iclaprim reaches lung concentrations that should be effective in the treatment of community-acquired pneumonia.

Comparative study of the in vitro activity of a new fluoroquinolone, ABT-492.

OBJECTIVES: The in vitro activity of a new fluoroquinolone, ABT-492, was determined. METHODS: MICs were compared with those of two beta-lactams, telithromycin, ciprofloxacin and four later generation fluoroquinolones. The effects of human serum and of inoculum concentration were also investigated. RESULTS: MIC data indicate that ABT-492 has potent activity against Gram-positive organisms with enhanced anti-staphylococcal activity compared with earlier fluoroquinolones, in addition to activity against beta-haemolytic streptococci, pneumococci including penicillin- and fluoroquinolone-resistant strains and vancomycin-susceptible and -resistant Enterococcus faecalis but not Enterococcus faecium. ABT-492 was the most active agent tested against Haemophilus influenzae, Moraxella catarrhalis, Neisseria meningitidis, fluoroquinolone-susceptible Neisseria gonorrhoeae and anaerobes. Good activity was observed for ABT-492 amongst the Enterobacteriaceae and anaerobes tested, but ciprofloxacin showed superior activity for species of Proteus, Morganella and Providencia, as well as for Pseudomonas spp. In common with the other fluoroquinolones tested, organisms with reduced susceptibility to ciprofloxacin had raised MIC(90)s to ABT-492. The one isolate of H. influenzae tested with reduced fluoroquinolone susceptibility had an ABT-492 MIC close to that of the population lacking a mechanism of quinolone resistance. ABT-492 was more active than ciprofloxacin against Chlamydia spp. An inoculum effect was observed with a number of isolates of Staphylococcus aureus, Streptococcus pneumoniae, E. faecium, Klebsiella spp. and Escherichia coli, in addition to moderately raised MICs in the presence of 70% serum protein. The clinical significance of these findings is yet to be determined. CONCLUSIONS: ABT-492 is a new fluoroquinolone with excellent activity against both Gram-positive and Gram-negative organisms, with many potential clinical uses.

Concentrations of garenoxacin in plasma, bronchial mucosa, alveolar macrophages and epithelial lining fluid following a single oral 600 mg dose in healthy adult subjects.

A microbiological assay was used to measure concentrations of garenoxacin (BMS-284756) in plasma, bronchial mucosa (BM), alveolar macrophages (AM) and epithelial lining fluid (ELF), following a single 600 mg oral dose. Twenty-four healthy subjects were allocated into four nominal time intervals after the dose, 2.5-3.5, 4.5-5.5, 10.5-11.5 and 23.5-24.5 h. Mean concentrations in plasma, BM, AM and ELF, respectively, for the four nominal time windows were for 2.5-3.5 h 10.0 mg/L (S.D. 2.8), 7.0 mg/kg (S.D. 1.3), 106.1 mg/L (S.D. 60.3) and 9.2 mg/L (S.D. 3.6); 4.5-5.5 h 8.7 mg/L (S.D. 2.2), 6.0 mg/kg (S.D. 1.9), 158.6 mg/L (S.D. 137.4) and 14.3 mg/L (S.D. 8.2); 10.5-11.5 h 6.1 mg/L (S.D. 1.9), 4.0 mg/kg (S.D. 1.4), 76.0 mg/L (S.D. 47.7) and 7.9 mg/L (S.D. 4.6); and 23.5-24.5 h 2.1 mg/L (S.D. 0.5), 1.7 mg/kg (S.D. 0.7), 30.7 mg/L (S.D. 12.9) and 3.3 mg/L (S.D. 2.3). Concentrations at all sites exceeded MIC(90)s for the common respiratory pathogens Haemophilus influenzae (0.03 mg/L), Moraxella catarrhalis (0.015 mg/L) and Streptococcus pneumoniae (0.06 mg/L). These data suggest that garenoxacin should be effective in the treatment of community-acquired pneumonia and chronic obstructive pulmonary disease.

Comparison of the in vitro activities of several new fluoroquinolones against respiratory pathogens and their abilities to select fluoroquinolone resistance.

In this study the in vitro activities and pharmacodynamic properties of moxifloxacin, levofloxacin, gatifloxacin and gemifloxacin were compared on recently isolated respiratory pathogens and strains of Streptococcus pneumoniae with known mechanisms of fluoroquinolone resistance. In addition, the resistance selection frequencies of moxifloxacin and levofloxacin on three recently isolated respiratory pathogens and four strains of S. pneumoniae with known mechanisms of fluoroquinolone resistance were investigated. The four fluoroquinolones had similar activities against both Moraxella catarrhalis (MIC(90)s 0.015-0.06 mg/L) and Haemophilus influenzae (MIC(90)s 0.008-0.03 mg/L). More marked differences in activity were noted with S. pneumoniae, with MIC(90)s of 0.25, 1, 0.5 and 0.03 mg/L for moxifloxacin, levofloxacin, gatifloxacin and gemifloxacin, respectively. With the S. pneumoniae strains, the four fluoroquinolones exhibited similar concentration-dependent time-kill kinetics. The resistance selection frequencies of levofloxacin were higher than those of moxifloxacin at concentrations equivalent to those at the end of the dosing interval. Therefore moxifloxacin may have less of an impact on the development of resistance than levofloxacin.

The in vitro activity of BMS-284756, a new des-fluorinated quinolone.

The in vitro activity of BMS-284756 (previously T-3811ME), a des-fluoro(6) quinolone, was investigated and compared with those of six other antimicrobial agents. Susceptibility tests were performed on 919 Gram-positive, Gram-negative (including nine quinolone-resistant Escherichia coli) and anaerobic bacteria, three Chlamydia isolates and four Mycobacteria spp. BMS-284756 was marginally less active against the Enterobacteriaceae, but was the most active quinolone against staphylococci, enterococci and peptostreptococci. Against Streptococcus pneumoniae, BMS-284756 and gemifloxacin were more active than other quinolones. The MIC(90) of BMS-284756 was > or = 2 mg/L for the following bacteria: E. coli (MIC(90) 16 mg/L), Acinetobacter spp. (8 mg/L), Pseudomonas aeruginosa (64 mg/L) and Enterococcus faecium (4 mg/L). The MIC of BMS-284756 for Mycobacterium spp. was within one dilution of the MIC of ciprofloxacin. BMS-284756 was markedly more active than ciprofloxacin against the Chlamydia isolates tested.

Lung concentrations of telithromycin after oral dosing.

Concentrations of telithromycin were measured in plasma, bronchial mucosa (BM), epithelial lining fluid (ELF) and alveolar macrophages (AM) following multiple oral doses. Concentrations were determined using a microbiological assay. There were 20 subjects in the study, allocated to three nominal time periods: 2, 12 and 24 h. Mean concentrations in plasma, BM, ELF and AM for 2, 12 and 24 h were as follows: 2 h, 1.86 mg/L, 3.88 mg/kg, 14.89 mg/L and 69.32 mg/L; 12 h, 0.23 mg/L, 1.41 mg/kg, 3.27 mg/L and 318.1 mg/L; and 24 h, 0.08 mg/L, 0.78 mg/kg, 0.97 mg/L and 161.57 mg/L. These concentrations of telithromycin in BM and ELF exceeded for 24 h the mean MIC90s of the common respiratory pathogens Streptococcus pneumoniae (0.12 mg/L) and Moraxella catarrhalis (0.03 mg/L), as well as the atypical microorganism Mycoplasma pneumoniae (0.001 mg/L), and suggest that telithromycin may be effective for the treatment of community-acquired pneumonia and chronic obstructive pulmonary disease.

A comparison of antimicrobial resistance rates in Gram-positive pathogens isolated in the UK from October 1996 to January 1997 and October 1997 to January 1998.

Rates of resistance for two consecutive years for 28 centres (10 Teaching, nine Associate Teaching and nine District General hospitals) in the UK were compared. Combined rates of resistance for each of the hospital types of Staphylococcus aureus to methicillin revealed an increase in the rate of resistance in Teaching hospitals (12.5% year 1, 23.5% year 2), but, for Associate Teaching and District General hospitals rates fell (Associate Teaching 19.1% year 1, 11.9% year 2; District General 16.5% year 1 and 11.3% year 2). Using conventional methodology to determine MICs, no strain was considered to have reduced susceptibility to vancomycin. Among coagulase-negative staphylococci, increased resistance was observed for Staphylococcus epidermidis to rifampicin, for Staphylococcus haemolyticus to clindamycin, for Staphylococcus saprophyticus to penicillin and for Staphylococcus spp. to clindamycin, methicillin and rifampicin. For Streptococcus pneumoniae an upward trend in low-level resistance to penicillin was observed (18 of the 28 centres), however, for high-level resistance the trend was in the opposite direction (only four centres showed an increase). For Enterococcus faecalis there was a trend to a fall in levels of resistance, the only exception being an increase in high-level gentamicin resistance (10.5% year 1, 15.1% year 2, P = 0.0388). For Enterococcus faecium rates of resistance were not significantly different except for increases in resistance to nitrofurantoin and rifampicin.

Tentative minimum inhibitory concentration and zone diameter breakpoints for moxifloxacin using BSAC criteria.

Tentative MIC and zone diameter breakpoints were determined for moxifloxacin using BSAC criteria. An MIC breakpoint of < or =1 mg/L, denoting sensitivity, is suggested for Enterobacteriaceae, staphylococci, haemophili, moraxellae, pneumococci and enterococci. For pseudomonads high and low breakpoints of 4 mg/L and 1 mg/L are suggested to allow for an intermediate category of sensitivity. A 1 microg moxifloxacin disc content is suggested for testing all of the organisms previously mentioned, except pseudomonads, for which a 5 microg disc is needed to discriminate between the intermediate and sensitive populations. Corresponding zone diameter breakpoints for a 1 microg disc are > or = 20 mm for Enterobacteriaceae and staphylococci, 18 mm for the respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) and 15 mm for enterococci. For Pseudomonas aeruginosa with a 5 microg disc, three bands are suggested for interpretation, that of > or = 25 mm (sensitive), 18-24 mm (intermediate) and < or = 17 mm (resistant).

Concentrations of moxifloxacin in serum and pulmonary compartments following a single 400 mg oral dose in patients undergoing fibre-optic bronchoscopy.

The concentrations of moxifloxacin achieved after a single 400 mg dose were measured in serum, epithelial lining fluid (ELF), alveolar macrophages (AM) and bronchial mucosa (BM). Concentrations were determined using a microbiological assay. Nineteen patients undergoing fibre-optic bronchoscopy were studied. Mean serum, ELF, AM and BM concentrations at 2.2, 12 and 24 h were as follows: 2.2 h: 3.2 mg/L, 20.7 mg/L, 56.7 mg/L, 5.4 mg/kg; 12 h: 1.1 mg/L, 5.9 mg/L, 54.1 mg/L, 2.0 mg/kg; 24 h: 0.5 mg/L, 3.6 mg/L, 35.9 mg/L, 1.1 mg/kg, respectively. These concentrations exceed the MIC(90)s for common respiratory pathogens such as Streptococcus pneumoniae (0.25 mg/L), Haemophilus influenzae (0.03 mg/L), Moraxella catarrhalis (0.12 mg/L), Chlamydia pneumoniae (0.12 mg/L) and Mycoplasma pneumoniae (0. 12 mg/L) and indicate that moxifloxacin should be effective in the treatment of community-acquired, lower respiratory tract infections.

Antimicrobial resistance in gram-positive pathogens isolated in the UK between October 1996 and January 1997.

Antimicrobial resistance in gram-positive pathogens from 30 centres in the UK (ten Teaching, ten Associate Teaching and ten District General Hospitals) was studied over a 4 month period between October 1996 and January 1997. High-level resistance (HLR) and low-level resistance (LLR) to penicillin amongst pneumococci was 3.3% and 3.4%, respectively. However, considerable variation in resistance rates was observed depending on geographical location (LLR range 0-15.4% and HLR range 0-30.8%). Considerable variation in resistance rates was also observed for Staphylococcus aureus to methicillin, with rates ranging from 0% to 56.7% depending on locality. Using conventional MIC methodology, none of the isolates of S. aureus was considered as having reduced sensitivity to vancomycin. However, eight isolates grew on Brain Heart Infusion Agar containing vancomycin (4 mg/L) after prolonged incubation and are therefore worthy of further investigation by electron microscopy. With Enterococcus faecalis, resistance rates were similar between the three types of hospital and only four isolates were considered resistant to glycopeptide antibiotics (one vanA and three vanB phenotype).

The concentrations of clinafloxacin in alveolar macrophages, epithelial lining fluid, bronchial mucosa and serum after administration of single 200 mg oral doses to patients undergoing fibre-optic bronchoscopy.

The concentrations of clinafloxacin were measured in serum, bronchial mucosa, alveolar macrophages and epithelial lining fluid after single 200 mg oral doses of clinafloxacin had been administered to 15 subjects who were undergoing bronchoscopy. Concentrations were measured using a microbiological assay method. Mean concentrations in serum, bronchial mucosa, alveolar macrophages and epithelial lining fluid at a mean of 1.27 h post-dose were 1.54, 2.65, 15.60 and 2.71 mg/L respectively. These site concentrations exceeded the MIC90 for common respiratory pathogens and indicate that clinafloxacin is likely to be effective in the treatment of a wide range of respiratory tract infections.

Concentrations of levofloxacin (HR 355) in the respiratory tract following a single oral dose in patients undergoing fibre-optic bronchoscopy.

Concentrations of levofloxacin were measured in bronchial biopsies, alveolar macrophages (AM), epithelial lining fluid (ELF) and serum following a single oral dose. Concentrations were measured by a microbiological assay method. A total of 35 patients undergoing fibre-optic bronchoscopy were studied. Mean serum, AM, ELF and biopsy concentrations were as follows. 0.5 h: 4.73 mg/L, 19.1 mg/L, 4.74 mg/L and 4.3 mg/kg; 1 h: 6.6 mg/L, 32.5 mg/L, 10.8 mg/L and 8.3 mg/kg; 2 h: 4.9 mg/L, 41.9 mg/L, 9.0 mg/L and 6.5 mg/kg; 4 h: 4.1 mg/L, 27.7 mg/L, 10.9 mg/L and 6.0 mg/kg; and 6-8 h: 4.0 mg/L, 38.4 mg/L, 9.6 mg/L and 4.0 mg/kg respectively. Mean serum and AM concentrations at 12-24 h were 1.2 and 13.9 mg/L respectively (concentrations in biopsy and ELF were only measurable in three of the six patients). These concentrations exceed the MIC90s of the common respiratory pathogens, Haemophilus influenzae (0.015 mg/L), Moraxella catarrhalis (0.06 mg/L) and Streptococcus pneumoniae (1 mg/L) and suggest that levofloxacin should be efficacious in the treatment of community- and hospital-acquired respiratory infection.