In vitro activity of garenoxacin against recent clinical isolates of Chlamydia pneumoniae

Potency and spectrum of garenoxacin tested against an international collection of skin and soft tissue infection pathogens: report from the SENTRY antimicrobial surveillance program (1999-2004)

The spectrum and potency of garenoxacin, a novel des-F(6)-quinolone, against a large international collection (11723 strains) of Gram-positive and Gram-negative bacterial pathogens that cause skin and soft tissue infections (SSTIs) were evaluated for the years 1999 to 2004. Consecutive nonduplicate bacterial isolates were collected from patients with documented community-acquired or nosocomial SSTI in >70 medical centers participating in the SENTRY Antimicrobial Surveillance Program in North America (37.4%), Europe (26.7%), Latin America (16.7%), and the Asia-Pacific region (19.2%). All isolates were tested using the reference broth microdilution methods against garenoxacin, ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, and representative comparator agents used for the empiric or directed therapy for SSTI. Ranking pathogens producing SSTI during these years included Staphylococcus aureus (42.8%), Pseudomonas aeruginosa (11.1%), Escherichia coli (9.0%), Enterococcus spp. (7.3%), Klebsiella spp. (4.8%), Enterobacter spp. (4.7%), beta-hemolytic streptococci (4.3%), coagulase-negative staphylococci (4.0%), Proteus mirabilis (2.5%), and Acinetobacter spp. (2.1%). Garenoxacin was the most potent agent tested against S. aureus and was at least 2-fold more active than gatifloxacin (MIC(50), 0.06 mg/L) and 8-fold more active than levofloxacin (MIC(50), 0.25 mg/L). Furthermore, garenoxacin was 2- to 8-fold more potent than the fluoroquinolones against beta-hemolytic and viridans group streptococci, as well as up to 4-fold more active against enterococci. Garenoxacin was largely comparable with the comparator fluoroquinolones against E. coli, Klebsiella spp., and Acinetobacter spp., but it is less active than these agents against P. aeruginosa. In summary, garenoxacin was documented to be the most potent quinolone when tested against key Gram-positive pathogens (S. aureus, beta-hemolytic streptococci, viridans group streptococci, and enterococci) and was similar in activity to these agents against other species (Enterobacteriaceae and Acinetobacter spp.). These in vitro data suggest that garenoxacin warrants further clinical studies in SSTI, especially against staphylococci and streptococcal pathogens.

[Antibiotherapy in children with atypical bacterial infections]

Atypical bacteria responsible for infections in children are mainly Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila. Atypical pneumonia is a frequent disease in children. Until recently, the outcome was thought to be rather benign and antibiotherapy to have only a minor impact on the prognosis. Recent studies have demonstrated that M. pneumoniae and C. pneumoniae were involved in a variety of infections, including acute upper airway disease, otitis and pharyngitis under five. Antibiotherapy was proven able to decrease the rate of complications and recurrence, notably episodes of wheezing and exacerbations of asthma. Atypical bacteria infections may be severe in immunocompromised children and children with underlying disease such as sickle cell anaemia. Whenever bacteriological documentation is lacking, one of the critical issues in choosing an antibiotic is to consider its activity against Streptococcus pneumoniae, especially in lower respiratory tract infections. The main available molecules are reviewed and discussed, with a special emphasis on ketolides, a newer family of molecules active on both atypical bacteria and S. pneumoniae.

Gatifloxacin in community-acquired respiratory tract infection

Gatifloxacin (Tequin, Kyorin Pharmaceutical Co. Ltd) is a new fluoroquinolone with a broad spectrum of activity for pathogens implicated in community-acquired respiratory tract infections, including Gram-positive, -negative and atypical bacteria. Excellent oral bioavailability, a half-life allowing once-daily administration and excellent penetration into respiratory tissues are desirable pharmacokinetic characteristics of gatifloxacin. Monte Carlo simulation of gatifloxacin in Streptococcus pneumoniae infection demonstrates that adequate levels of pharmacokinetic/pharmacodynamic parameters are obtained with gatifloxacin in almost all instances. In randomised, controlled trials and a large open-label, community-based study, gatifloxacin has shown excellent clinical and bacteriological efficacy in acute bacterial sinusitis, acute exacerbations of chronic bronchitis and community-acquired pneumonia. Current guidelines recommend the initial empiric use of gatifloxacin (along with the other new fluoroquinolones) for community-acquired respiratory tract infection in patients who have increased likelihood of infection with resistant pathogens. Another group of patients where this agent is recommended for initial antimicrobial therapy are those who, because of underlying disease and/or comorbid conditions, need an antibiotic with high antimicrobial efficacy to achieve optimal outcomes.

In vitro activity of a novel diaminopyrimidine compound, iclaprim, against Chlamydia trachomatis and C. pneumoniae

The in vitro activities of iclaprim, a novel dihydrofolate reductase inhibitor, azithromycin, and levofloxacin were tested against 10 strains of Chlamydia trachomatis and 10 isolates of Chlamydia pneumoniae. For C. trachomatis and C. pneumoniae, the iclaprim MIC and minimal bactericidal concentration at which 90% of isolates were inhibited (MIC(90) and MBC(90)) were 0.5 micro g/ml, compared to an azithromycin MIC(90) and MBC(90) of 0.125 micro g/ml and levofloxacin MIC(90)s and MBC(90)s of 1 micro g/ml for C. trachomatis and 0.5 micro g/ml for C. pneumoniae.