Susceptibility surveillance of U.S. respiratory pathogen isolates to newer macrolide and azalide antibiotics

Azithromycin and clarithromycin are both highly active in vitro against Gram-positive respiratory pathogens, but azithromycin is substantially more potent against Haemophilus influenzae. We investigated the susceptibility of H. influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and S. pyogenes to azithromycin and clarithromycin, and determined the prevalence of beta-lactamase production in H. influenzae and M. catarrhalis. Results from three geographic regions of the USA were compared. A significantly greater proportion of H. influenzae isolates were susceptible to azithromycin than to clarithromycin (95.7% vs 63.1%, P < 0.001). M. catarrhalis, S. pneumoniae and S. pyogenes were highly susceptible to both antibiotics with no significant differences in susceptibility. beta-Lactamase was produced by 94.8% of M. catarrhalis isolates and 35.6% of H. influenzae.     

Antimicrobial activities of macrolides against recent clinical isolates,and analysis of resistant mechanisms

We examined antibacterial activities of 4 kinds of macrolides, erythromycin (EM), clarithromycin (CAM), azithromycin (AZM) and rokitamycin (RKM), against 6 bacterial species of clinical strains isoleted in 2002. Bacterial isolates used were each 50 strains of methicillin-susceptible Staphylococcus aureus (MSSA), Streptococcus pyogenes, Streptococcus agalactiae, Moraxella (Branhamella) catarrhalis, Haemophilus influenzae and 43 strains of Streptococcus pneumoniae. S. agalactiae were derived from gynecological samples, and other species were isolated from respiratory specimens. Antimicrobial activities against S. aureus, S. pyogenes, S. agalactiae, M. catarrhalis and H. influenzae of 14-membered macrolides, such as EM and CAM, were higher than those of 16-membered macrolide, RKM. By contrast, against S. pneumoniae, RKM was more effective than 14-membered macrolides. Six, three and four strains of S. aureus, S. pyogenes and S. agalactiae, respectively, were resistant to macrolides. Thirty-five among 43 pneumococcal isolates were resistant, and 15 of the 35 were highly-resistant, MIC of > 128 micrograms/ml, to any one of EM, CAM or AZM. Isolation frequency of resistant strains to RKM was lower than those to 14- and 15-membered macrolides: only one strain was highly-resistant and 12 were intermediately-resistant. No resistant strain was recognized in M. catarrhalis and H. influenzae. Further, we analyzed the resistant mechanisms, methylation or efflux, of macrolide resistant strains by the double-disk method. Methylation was major mechanism in S. aureus, and in S. pyogenes, all of the resistance was caused by methylation. In S. agalactiae and S. pneumoniae, methylation and efflux shared about half and half.     

Pharmacological and pharmacokinetic properties of azithromycin (Zithromac), a novel 15-membered ring macrolide antibacterial agent]

Azithromycin (Zithromac), a 15-membered ring macrolide antibacterial agent, was approved to be manufactured in Japan in March 2000. It showed good in vitro and/or in vivo antibacterial activities against Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Peptostreptococcus micros, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae and Chlamydia pneumoniae. Its activity against H. influenzae was particularly more potent than that of currently used macrolide antibacterial agents. After oral administration to patients, azithromycin was readily absorbed and became widely distributed throughout the body, achieving higher concentrations in tissues and phagocytic cells than in serum or plasma. Its distribution into phagocytes was as high as more than 10 times that of erythromycin, and azithromycin was readily released from phagocytes in the presence of S. aureus. In experimentally infected mice, the concentration of azithromycin was higher in infected tissues than in uninfected tissues, which indicated that azithromycin was selectively delivered to infected tissues by migrating phagocytes. These pharmacological and pharmacokinetic properties were reflected in good clinical results for the treatment of respiratory infections and other infections with once daily dosing for 3 days.     

In vitro activity of telithromycin compared with macrolides and fluoroquinolones against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis

The in vitro activity of telithromycin was compared with erythromycin A, azithromycin, clarithromycin, moxifloxacin, gemifloxacin, levofloxacin, ciprofloxacin, penicillin G, ampicillin, cefuroxime and ceftriaxone against 336 consecutive strains (83 Streptococcus pneumoniae, 168 Haemophilus influenzae and 85 Moraxella catarrhalis) isolated from patients with community-acquired respiratory tract infections. Telithromycin (MIC(90), 0.008 mg/l) was the most active drug against S. pneumoniae. Telithromycin was also highly active against M. catarrhalis (MIC(90), 0.06 mg/l), but less active against H. influenzae (MIC(90), 4 mg/l).     

Comparative in vitro activity of thiamphenicol-glycinate and thiamphenicol-glycinate-acetylcysteinate and other antimicrobials against respiratory pathogens

Thiamphenicol-glycinate-acetylcysteinate (TGA; CAS 20192-91-0) is widely used for the treatment of infections of varied aetiology. The aim of this study was to compare the antibacterial activity of thiamphenicol-glycinate (TG; CAS 15318-45-3), TGA, amoxicillin (CAS 61336-70-7) plus clavulanic acid (CAS 58001-44-8), azithromycin (CAS 83905-01-5) and ceftriaxone (CAS 104376-79-6). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined against Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae according to the National Committee for Clinical Laboratory Standards (NCCLS) methods. The effects of changes in assay conditions were also examined. The activity of TG and TGA was similar to that of amoxicillin plus clavulanic acid, with the exception of methicillin resistant S. aureus. Azithromycin and ceftriaxone were characterised by a limited activity against gram-positive cocci and methicillin resistant and cefinase-positive S. aureus, respectively. TG and TGA are characterized by a wide spectrum of activity, comparable to that of recent commercialized antibiotics for treatment of respiratory tract infections.     

Plasma bactericidal activity of a new C-5 methyl fluoroquinolone after oral doses of 400 and 800 mg.

The plasma bactericidal activity of a new C-5 methyl fluoroquinolone, OPC-17116, was determined after once-daily oral ingestion of 400 mg and 800 mg in normal, healthy volunteers. OPC-17116 at a 400-mg dose produced plasma bactericidal titers greater than or equal to 1:16 at 12 hours against Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Haemophilus influenzae, and Moraxella catarrhalis. OPC-17116 bactericidal titers against Pseudomonas aeruginosa were 1:2 or 1:4 at 6 and 12 hours. The plasma bactericidal titers against Streptococcus pyogenes and Streptococcus pneumoniae were 1:4 or greater, but bactericidal titers against Staphylococcus aureus were 1:2 at 12 hours and less than 1:2 at 24 hours. The 800-mg dose of OPC-17116 produced bactericidal titers of at least 1:32 at 12 hours for the Enterobacteriaceae, Haemophilus, and Moraxella, and 1:4 for S. pyogenes and S. pneumoniae, but bactericidal titers against S. aureus were 1:2. These data would suggest that an 800-mg dose of OPC-17116 taken orally once daily would provide adequate concentrations to treat infections due to the pathogens examined in this study.     

Bactericidal activity and postantibiotic effect of cefdinir (Cl 983, FK 482) against selected pathogens.

The bactericidal activity and the postantibiotic effect (PAE) of cefdinir (Cl 983, FK 482) (CDR), were determined against Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis and Escherichia coli (5 strains each) in comparison to erythromycin (E), cotrimoxazole (SXT) and amoxicillin-clavulanic acid (AMC). Kinetic studies of kill showed that CDR was rapidly bactericidal at concentrations 2 and 4 times the minimum inhibitory concentration (MIC): a reduction of 99.9% in CFU values was observed after 6-8 h for many of the isolates tested. As expected, a PAE was observed when S. aureus was treated with CDR at MIC (range of individual values for 5 strains 0.8-1.5 h) and 4 x MIC (range 1.1-1.4 h). Moreover, CDR showed a significant PAE at both its MIC and 4 x MIC against S. pneumoniae (range 0.5-1.0 h and 0.9-1.1 h), H. influenzae (range 0.4-0.7 h and 0.4-0.8 h), B. catarrhalis (range 0.5-0.7 h and 0.65-0.95 h) and E. coli (range 0.5-0.6 h and 0.5-0.7 h). The good bactericidal activity and the significant PAE of CDR against Gram-positive and Gram-negative bacteria (including respiratory pathogens) are a promising indication for the clinical efficacy of this cephalosporin in several bacterial infections.     

Multicentre study of the in vitro evaluation of moxifloxacin and other quinolones against community acquired respiratory pathogens.

The in vitro activity of moxifloxacin was compared with that of ciprofloxacin, levofloxacin, ofloxacin and trovafloxacin against 710 strains (180 Streptococcus pneumoniae, 180 Haemophilus influenzae, 160 Moraxella catarrhalis and 190 Streptococcus pyogenes) isolated from patients with community-acquired respiratory tract infections. MIC values for moxifloxacin, trovafloxacin were 0.25/0.25, 0.03/0.03, 0.06/0.03 and 0.125/0.0125 mg/l for S. pneumoniae, H. influenzae, M. catharralis and S. pyogenes. Based upon the MIC(90) values and the MIC distributions, moxifloxacin and trovafloxacin were the most active of the quinolones tested. They showed enhanced activity against Gram-positive organisms including penicillin non susceptible S. pneumoniae strains. Moxifloxacin was also highly active against ciprofloxacin-resistant S. pneumoniae strains.     

Comparative in vitro potency of amoxycillin-clavulanic acid and four oral agents against recent North American clinical isolates from a global surveillance study

The in vitro activity of amoxycillin-clavulanic acid was compared with four comparator oral antimicrobial agents; ampicillin, azithromycin, cefuroxime and trimethoprim-sulphamethoxazole against 4536 recent clinical isolates covering 29 species isolated in the US and Canada between 1997 and 1999. Based upon Minimum inhibitory concentrations (MICs), amoxycillin-clavulanic acid was the most active agent against many Gram-positive species and phenotypes including methicillin susceptible Staphylococcus aureus (MSSA) Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes, Streptococcus pneumoniae including penicillin intermediate and macrolide resistant strains and was as active as ampicillin against Streptococcus agalactiae, penicillin resistant S. pneumoniae and viridans streptococci. Against Enterobacteriaceae amoxycillin-clavulanic acid in general, displayed weak activity with only Proteus mirabilis and Proteus vulgaris displaying levels of susceptibility above the 90th percentile. Amoxycillin-clavulanic acid had significant activity against many species of Gram-negative non-Enterobacteriaceae including Haemophilus influenzae, Haemophilus parainfluenzae and Moraxella catarrhalis but negligible activity against Burkholderia cepacia, Pseudomonas aeruginosa and Stenotrophomonas maltophilia. Amoxycillin-clavulanic acid continues to retain excellent activity against the majority of targeted pathogens despite 20 years of clinical use.     

Antibacterial activity of gatifloxacin against various fresh clinical isolates in 2002

Antibacterial activities of gatifloxacin (GFLX) and other antibacterial drugs against various fresh clinical strains (800 isolates) isolated from specimens of patients in 2002 were compared. GFLX was more active than levofloxacin and ciprofloxacin against Gram-positive bacteria such as methicillin susceptible Staphylococcus aureus and Streptococcus pneumoniae. For these isolates, clarithromycin and azithromycin were less active (MIC90; > 16- > 64 micrograms/mL), GFLX was more active than cefdinir. For Escherichia coli, Klebsiella pneumoniae, Acinetobacter species, Haemophilus influenzae and Moraxella (Branhamella) catarrhalis, three quinolones including GFLX were potently active (MIC90; < or = 0.06-0.5 microgram/mL). Pseudomonas aeruginosa isolated from urinary tract infections were resistant to three quinolones including GFLX (MIC90; 32-64 micrograms/mL), however P. aeruginosa isolated from respiratory and otolaryngological infections were more susceptible (MIC90; 0.5-2 micrograms/mL). Quinolones were less active against Neisseria gonorrhoeae as compared with the cephem antibiotics tested, but GFLX was the most active against N. gonorrhoeae among the quinolones tested. In this study, we investigated activity of GFLX against fresh clinical strains isolated early in 2002, GFLX is widely and potently active against S. aureus, S. pneumoniae and various Gram-negative bacteria.     

Moxifloxacin activity against clinical isolates compared with the activity of ciprofloxacin

The activity of moxifloxacin, a new 8-methoxyquinolone, was compared in vitro with the activity of ciprofloxacin against clinical strains isolated from various sites of infection. The mode MIC values of moxifloxacin were superior to those of ciprofloxacin against Streptococcus pneumoniae, methicillin-susceptible and -resistant Staphylococcus aureus, Enterococcus spp., Escherichia coli and Acinetobacter spp., while ciprofloxacin was more active against Klebsiella pneumoniae and Pseudomonas spp. Both antibiotics had similar activity against Haemophilus influenzae, Moraxella catarrhalis and Enterobacter spp.     

Antibacterial activity of tosufloxacin against major organisms detected from patients with respiratory infections

We determined the susceptibility of bacteria which were isolated from the patients with respiratory infections between January and October 2005, to tosufloxacin and other fluoroquinolones. A total of 900 isolate including 300 Streptococcus pneumoniae, 100 Streptococcus pyogenes, 100 Moraxella catarrhalis, 200 Haemophilus influenzae, 100 Klebsiella pneumoniae and 100 Pseudomonas aeruginosa were tested. Tosufloxacin, gatifloxacin, levofloxacin, moxifloxacin, ciprofloxacin and prulifloxacin were used as the test antimicrobials. Tosufloxacin, gatifloxacin and moxifloxacin were potent antibiotics tested for the antibacterial activity against Streptococcus including penicillin-resistant S. pneumoniae; the MIC90 were 0.12-0.5/ micromL. Fluoroquinolones exerted the potent antibacterial activity against M. catarrhalis and H. influenzae; the MIC90 of fluoroquinolones tested were < or =0.06 microg/mL. Tosufloxacin, ciprofloxacin and prulifloxacin showed to be more active against K. pneumoniae and P. aeruginosa, but parts of some strains were resistant. These results indicate that tosufloxacin has the potent antibacterial activity against major organisms detected from patients with respiratory infections. Since it was approved in 1990, tosufloxacin was considered to be useful as a therapeutic antimicrobial for the treatment of respiratory infections.     

Telithromycin: a new ketolide antimicrobial for treatment of respiratory tract infections

Telithromycin is a new ketolide antimicrobial, specifically developed for the treatment of community-acquired respiratory tract infections. It has a wide spectrum of antibacterial activity against common respiratory pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. It also has activity against atypical pathogens, such as Chlamydia pneumoniae, Legionella pneumophila and Mycoplasma pneumoniae. Telithromycin maintains activity against beta-lactam and macrolide-resistant respiratory tract pathogens and does not appear to induce cross-resistance to other members of the macrolide-lincosamide-streptogramin (MLS) group of antimicrobials. It demonstrates bactericidal activity against S. pneumoniae and H. influenzae and has a prolonged concentration-dependent post-antibiotic effect (PAE) in vitro. The drug has favourable pharmacokinetics following oral administration. It is well absorbed, achieves good plasma levels and is highly concentrated in pulmonary tissues and white blood cells. In clinical trials, telithromycin given orally at a dose of 800 mg once daily for 5 - 10 days was as effective as comparator antimicrobials for the treatment of adults with community-acquired pneumonia, acute exacerbations of chronic bronchitis, acute maxillary sinusitis and group A-beta-haemolytic streptococcal pharyngitis or tonsillitis. The adverse events and safety profile were similar to comparator antimicrobials. The most common adverse events were diarrhoea, nausea, headache and dizziness. Telithromycin should provide an effective, convenient and well-tolerated once-daily oral therapy for treatment of respiratory infections.     

In vitro antibacterial activity of FK041, a new orally active cephalosporin.

The in vitro activity of FK041, a new orally active cephem antibiotic, against a wide variety of clinical isolates of bacteria was investigated and compared with those of cefdinir (CFDN) and cefditoren (CDTR). FK041 exhibited broad spectrum activity against reference strains of Gram-positive and Gram-negative aerobes and anaerobes. FK041 was active against clinical isolates of Gram-positive organisms except Enterococcus faecalis with MIC90s less than 1.56 microg/ml. FK041 was more active than CFDN and CDTR against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae and was comparable to CFDN and CDTR against Streptococcus pyogenes and Streptococcus pneumoniae. FK041 had no activity against methicillin-resistant staphylococci, like CFDN and CDTR. FK041 showed moderate activity against penicillin-resistant S. pneumoniae with an MIC range of 0.05 approximately 3.13 microg/ml, and was superior to CFDN but inferior to CDTR. Against clinical isolates of many Gram-negative organisms such as Neisseria gonorrhoeae, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, FK041 had good activity comparable or superior to those of CFDN and CDTR. However, it was inferior to CDTR in activity against Moraxella catarrhalis, Haemophilus influenzae, Morganella morganii, and Serratia marcescens, and was inactive against Pseudomonas aeruginosa. With FK041 a small difference between MIC and MBC against S. aureus, E. coli, K. pneumoniae, and H. influenzae was found, indicating that its action is bactericidal against these species. FK041 was stable to group 2beta-lactamase hydrolysis but was unstable to group 1beta-lactamase hydrolysis. The stability of FK041 to these enzymes was similar to those of CFDN and CDTR. FK041 showed high affinity for the main penicillin-binding proteins (PBPs) of S. aureus (PBP 3, 2, and 1) and E. coli (PBP 3, 4, lbs, 2, and 1a).     

Post-antibiotic effect of azithromycin on respiratory tract pathogens

Azithromycin is a new azalide antibiotic with structural modifications that confer to the molecule acid stability, extension of antibacterial spectrum that includes important Gram-negative pathogens, long elimination half-life, and tendency to concentrate into various tissues where it persists for extended periods of time. The existence and length of a post-antibiotic effect (PAE), an important parameter for the characterization of new antibiotic molecules, has not yet been evaluated for this agent. In this study the PAE of azithromycin was assessed against representative respiratory pathogens included in the in vitro antimicrobial activity of the drug. The results obtained indicate that azithromycin produce a significant PAE on all Gram-positive and Gram-negative bacteria tested, resulting in an average value of 3.5 h for both S. pyogenes and S. pneumoniae, 3 h for B. catarrhalis and H. influenzae, and 2 h for Klebsiella spp. These findings support previous reports underlining the remarkable in vitro activity of azithromycin against H. influenzae, a pathogen poorly susceptible to the classical macrolides. Furthermore, the present demonstration of the existence of a long PAE of azithromycin against other Gram-positive and Gram-negative bacteria extends the pharmacokinetic advantages of the drug and strongly supports the application of this azalide in the therapy of respiratory infections.     

局部外用药Retapamulin的药理与临床研究进展

Retapamulin(SB-275833)是截短侧耳素类化合物的半合成衍生物,为一种选择性细菌蛋白质合成抑制剂,在体外对G 菌包括金葡球菌、化脓链球菌和一些G-菌(如流感嗜血杆菌、卡他莫拉菌)均有极好的抗菌活性。2007年4月通过美国FDA审批,目前该产品尚未在中国上市,文中对其作用机制、抗菌活性、药动学、临床研究及不良反应等做一综述。     

Activities of antimicrobial agents against 8,474 clinical isolates obtained from 37 medical institutions during 2000 in Japan

A survey was conducted to determine the antimicrobial activity of fluoroquinolones and other antimicrobial agents against 8,474 clinical isolates obtained from 37 Japanese medical institutions in 2000. A total of 25 antimicrobial agents were used, comprising 4 fluoroquinolones, 13 beta-lactams, minocycline, chloramphenicol, clarithromycin, azithromycin, gentamicin, amikacin, sulfamethoxazole-trimethoprim, and vancomycin. A high resistance rate of over 85% against fluoroquinolones was exhibited by methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium. Isolates showing resistance to fluoroquinolones among methicillin-resistant coagulase-negative Staphylococci, Enterococcus faecalis, and Pseudomonas aeruginosa from UTI accounted for 30-60%. However, many of the common pathogens were still susceptible to fluoroquinolones, such as Streptococcus pneumoniae (including penicillin-resistant isolates), Streptococcus pyogenes, methicillin-susceptible S. aureus (MSSA), methicillin-susceptible coagulase-negative Staphylococci, Moraxella catarrhalis, the Enterobacteriaceae family, and Haemophilus influenzae (including ampicillin-resistant isolates). About 85% of P. aeruginosa isolated from RTI were susceptible to fluoroquinolones. In conclusion, this survey of sensitivity to antimicrobial agents clearly indicated trend for increasing resistance to fluoroquinolones among MRSA, Enterococci, and P. aeruginosa isolated from UTI, although fluoroquinolones are still effective against other organisms and P. aeruginosa from RTI as has been demonstrated in previous studies.     

头孢唑兰对临床分离菌株体外抗菌作用评价

目的：评价头孢唑兰对临床分离菌株的体外抗菌作用,为头孢唑兰的临床使用提供参考依据。方法：用浊度法测定头孢唑兰对临床分离的无乳链球菌、甲氧西林敏感的金黄色葡萄球菌（MSSA）、甲氧西林敏感表皮葡萄球菌（MSSE）、肺炎链球菌、粪肠球菌、化脓性链球菌、大肠埃希菌、肺炎克雷伯菌、流感嗜血杆菌、阴沟肠杆菌、奇异变形杆菌、铜绿假单胞菌、产气肠杆菌等的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）,平行试验3次,观察头孢唑兰培养液的的浊度。结果：头孢唑兰对化脓性链球菌、肺炎链球菌、无乳链球菌、MSSE、MSSA、粪肠球菌6种临床分离G~＋菌株的MIC分别为0.064,0.125,0.125,0.5,2,8μg·ml~（-1）,MBC分别为0.125,0.25,0.25,1,4,16μg·ml~（-1）;对肺炎克雷伯菌、大肠埃希菌、奇异变形杆菌、流感嗜血杆菌、产气肠杆菌、铜绿假单胞菌、阴沟肠杆菌7种临床分离G~-菌株的MIC分别为0.125,0.125,0.25,1,1,8,32μg·ml~（-1）,MBC分别为0.25,0.25,0.5,2,2,16,64μg·ml~（-1）。结论：头孢唑兰具有较强的抑菌及杀菌作用。     

Telithromycin: a new ketolide antimicrobial for treatment of respiratory tract infections

Telithromycin is a new ketolide antimicrobial, specifically developed for the treatment of community-acquired respiratory tract infections. It has a wide spectrum of antibacterial activity against common respiratory pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. It also has activity against atypical pathogens, such as Chlamydia pneumoniae, Legionella pneumophila and Mycoplasma pneumoniae. Telithromycin maintains activity against β-lactam and macrolide-resistant respiratory tract pathogens and does not appear to induce cross-resistance to other members of the macrolide-lincosamide-streptogramin (MLS) group of antimicrobials. It demonstrates bactericidal activity against S. pneumoniae and H. influenzae and has a prolonged concentration-dependent post-antibiotic effect (PAE) in vitro. The drug has favourable pharmacokinetics following oral administration. It is well absorbed, achieves good plasma levels and is highly concentrated in pulmonary tissues and white blood cells. In clinical trials, telithromycin given orally at a dose of 800 mg once daily for 5 - 10 days was as effective as comparator antimicrobials for the treatment of adults with community-acquired pneumonia, acute exacerbations of chronic bronchitis, acute maxillary sinusitis and group A-β-haemolytic streptococcal pharyngitis or tonsillitis. The adverse events and safety profile were similar to comparator antimicrobials. The most common adverse events were diarrhoea, nausea, headache and dizziness. Telithromycin should provide an effective, convenient and well-tolerated once-daily oral therapy for treatment of respiratory infections.     

In vitro susceptibility of 4903 bacterial isolates to gemifloxacin--an advanced fluoroquinolone

The in vitro activity of gemifloxacin against over 4900 bacterial isolates was determined by microbroth dilution with interpretation in accordance with NCCLS guidelines. Susceptibility results were compared with those for ciprofloxacin, gatifloxacin, levofloxacin and moxifloxacin. Gemifloxacin and the other fluoroquinolones were not affected by either beta-lactamase production or penicillin-resistance in Streptococcus pneumoniae. The MIC90 values for gemifloxacin were: S. pneumoniae 0.063 mg/l; Haemophilus influenzae 0.016 mg/l; Moraxella catarrhalis 0.008 mg/l, methicillin-susceptible Staphylococcus aureus 0.063 mg/l; methicillin-susceptible Streptococcus pyogenes 0.031 mg/l; Enterobacteriaceae 0.031-0.16 mg/l; Pseudomonas aeruginosa 4 mg/l; Neisseria meningitidis 0.008 mg/l. The MIC90 for gemifloxacin was lower than those for the other quinolones tested against S. pneumoniae (ciprofloxacin 2-4 mg/l, gatifloxacin 0.5 mg/l, levofloxacin 1-2 mg/l, moxifloxacin 0.25 mg/l). This study confirms the enhanced potent activity of gemifloxacin against Gram-positive pathogens, its broad-spectrum, Gram-negative activity and indicates that gemifloxacin is likely to have an important role in treating patients with Gram-positive and/or Gram-negative infections.