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

Intrapulmonary Pharmacokinetics of Lascufloxacin in Healthy Adult Volunteers

This study was performed to investigate the intrapulmonary penetration of lascufloxacin in humans. Thirty healthy adult male Japanese subjects, allocated into five groups, received lascufloxacin in a single oral dose of 75 mg. Bronchoalveolar lavage and blood sampling were performed simultaneously in each subject at 1, 2, 4, 6, or 24 h after administration, and lascufloxacin concentrations in plasma, epithelial lining fluid, and alveolar macrophages were determined. Lascufloxacin was rapidly distributed to the epithelial lining fluid with a time to maximum drug concentration (T_max) of 1 h, which was identical to that in plasma. The maximum concentration of drug (C_max) values in plasma, epithelial lining fluid, and alveolar macrophages were 0.576, 12.3, and 21.8 μg/ml, respectively. The corresponding area under the concentration-time curve from 0 to 24 h (AUC_0-24) values were 7.67, 123, and 325 μg · h/ml. The mean drug concentrations in the epithelial lining fluid and alveolar macrophages were much higher than those in plasma at all time points examined, and the average site-to-free plasma concentration ratios fell within the ranges of 57.5 to 86.4 and 71.0 to 217, respectively. Drug levels in epithelial lining fluid and alveolar macrophages exceeded the MIC₉₀ values for common respiratory pathogens. (This study was registered at JAPIC under registration number JapicCTI-142547.).

A Review of New Fluoroquinolones : Focus on their Use in Respiratory Tract Infections

The new respiratory fluoroquinolones (gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, and on the horizon, garenoxacin) offer many improved qualities over older agents such as ciprofloxacin. These include retaining excellent activity against Gram-negative bacilli, with improved Gram-positive activity (including Streptococcus pneumoniae and Staphylococcus aureus). In addition, gatifloxacin, moxifloxacin and garenoxacin all demonstrate increased anaerobic activity (including activity against Bacteroides fragilis). The new fluoroquinolones possess greater bioavailability and longer serum half-lives compared with ciprofloxacin. The new fluoroquinolones allow for once-daily administration, which may improve patient adherence. The high bioavailability allows for rapid step down from intravenous administration to oral therapy, minimizing unnecessary hospitalization, which may decrease costs and improve quality of life of patients. Clinical trials involving the treatment of community-acquired respiratory infections (acute exacerbations of chronic bronchitis, acute sinusitis, and community-acquired pneumonia) demonstrate high bacterial eradication rates and clinical cure rates. In the treatment of community-acquired respiratory tract infections, the various new fluoroquinolones appear to be comparable to each other, but may be more effective than macrolide or cephalosporin-based regimens. However, additional data are required before it can be emphatically stated that the new fluoroquinolones as a class are responsible for better outcomes than comparators in community-acquired respiratory infections. Gemifloxacin (except for higher rates of hypersensitivity), levofloxacin, and moxifloxacin have relatively mild adverse effects that are more or less comparable to ciprofloxacin. In our opinion, gatifloxacin should not be used, due to glucose alterations which may be serious. Although all new fluoroquinolones react with metal ion-containing drugs (antacids), other drug interactions are relatively mild compared with ciprofloxacin. The new fluoroquinolones gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin have much to offer in terms of bacterial eradication, including activity against resistant respiratory pathogens such as penicillin-resistant, macrolide-resistant, and multidrug-resistant S. pneumoniae. However, ciprofloxacin-resistant organisms, including ciprofloxacin-resistant S. pneumoniae, are becoming more prevalent, thus prudent use must be exercised when prescribing these valuable agents.

Penetration of anti-infective agents into pulmonary epithelial lining fluid: focus on antibacterial agents

The exposure-response relationship of anti-infective agents at the site of infection is currently being re-examined. Epithelial lining fluid (ELF) has been suggested as the site (compartment) of antimicrobial activity against lung infections caused by extracellular pathogens. There have been an extensive number of studies conducted during the past 20 years to determine drug penetration into ELF and to compare plasma and ELF concentrations of anti-infective agents. The majority of these studies estimated ELF drug concentrations by the method of urea dilution and involved either healthy adult subjects or patients undergoing diagnostic bronchoscopy. Antibacterial agents such as macrolides, ketolides, newer fluoroquinolones and oxazolidinones have ELF to plasma concentration ratios of >1. In comparison, β-lactams, aminoglycosides and glycopeptides have ELF to plasma concentration ratios of ≤1. Potential explanations (e.g. drug transporters, overestimation of the ELF volume, lysis of cells) for why these differences in ELF penetration occur among antibacterial classes need further investigation. The relationship between ELF concentrations and clinical outcomes has been under-studied. In vitro pharmacodynamic models, using simulated ELF and plasma concentrations, have been used to examine the eradication rates of resistant and susceptible pathogens and to explain why selected anti-infective agents (e.g. those with ELF to plasma concentration ratios of >1) are less likely to be associated with clinical treatment failures. Population pharmacokinetic modelling and Monte Carlo simulations have recently been used and permit ELF and plasma concentrations to be evaluated with regard to achievement of target attainment rates. These mathematical modelling techniques have also allowed further examination of drug doses and differences in the time courses of ELF and plasma concentrations as potential explanations for clinical and microbiological effects seen in clinical trials. Further studies are warranted in patients with lower respiratory tract infections to confirm and explore the relationships between ELF concentrations, clinical and microbiological outcomes, and pharmacodynamic parameters.

In vitro and in vivo antibacterial activities of garenoxacin against group G Streptococcus dysgalactiae subsp. equisimilis

In this study, garenoxacin showed potent in vitro activity against clinical isolates of group G Streptococcus dysgalactiae subsp. equisimilis [minimum inhibitory concentration for 90% of the organisms (MIC(90)) = 0.125 μg/mL] and was superior to levofloxacin (MIC(90) = 1 μg/mL) and moxifloxacin (MIC(90)=0.25 μg/mL). In experimental pneumonia caused by group G S. dysgalactiae subsp. equisimilis in mice, the effective dose for 50% survival (ED(50)) of garenoxacin following single oral administration was 1.87 mg/kg, >10.7-fold and 4.6-fold less than the ED(50) values of levofloxacin (>20 mg/kg) and moxifloxacin (8.54 mg/kg), respectively. The area under the free serum concentration-time curve from 0-24 h (fAUC(0-24))/MIC ratio of garenoxacin in serum following oral administration of 20 mg/kg was 73.2, which was 8.7-11.4-fold and 1.4-fold greater than that of levofloxacin (6.44-8.46) and moxifloxacin (51.4), respectively. These results suggest that garenoxacin has potential for the treatment of infectious diseases caused by S. dysgalactiae subsp. equisimilis.

Treatment of acute bacterial exacerbations of chronic bronchitis

BACKGROUND

Controversies persist regarding the optimal management of patients with acute exacerbations of chronic bronchitis (AECB).

OBJECTIVE

To evaluate the available evidence on relevant issues, namely the need for administering antimicrobials in patients with AECB, the identification of the subgroup of patients with AECB needing antibiotics, the antimicrobial regimen of choice and its optimal duration, the existence of new agents, and the value of non-antimicrobial regimens for AECB.

METHODS

Data from various sources of evidence, including recent relevant meta-analyses, were appraised.

CONCLUSION

Administration of antimicrobial agents, combined with bronchodilators and systemic corticosteroids, is warranted in approximately half of AECBs (i.e., in bacterial exacerbations) to achieve a survival benefit. Simple clinical parameters, mainly sputum purulence, and biomarkers, such as procalcitonin, are useful in identifying patients requiring antibiotics. Advanced antibiotics (quinolones, macrolides, or amoxicillin/clavulanic acid) are more effective than 'old' antibiotics in AECB; regimens of short duration (for 5 days) are preferred. There is no difference between several classes of advanced antibiotics regarding their short-term effectiveness; however, quinolones are associated with better long-term outcomes than macrolides. Newer quinolones and new formulations of macrolides enrich clinicians' armamentarium against AECB.

Oral garenoxacin in the treatment of acute bacterial maxillary sinusitis: a Phase II, multicenter, noncomparative, open-label study in adult patients undergoing sinus aspiration

BACKGROUND

Garenoxacin is a des-F(6)-quinolone with in vitro activity against key respiratory pathogens, including Streptococcus pneumoniae, Hemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis. Limited data are available regarding the effect of garenoxacin in the treatment of acute bacterial sinusitis.

OBJECTIVE

The aim of this study was to assess the efficacy and tolerability of garenoxacin in adults with acute bacterial maxillary sinusitis undergoing a pre-treatment diagnostic sinus aspirate.

METHODS

This Phase II, multicenter, noncomparative, open-label study was conducted at 30 centers in the United States, Mexico, Argentina, and Europe. Male and female patients aged 18 to 80 years with clinical signs and symptoms lasting >or=5 but <or=28 days and radiologic signs (air-fluid level, opacification, mucosal thickening) of acute maxillary sinusitis were eligible. The entry criteria for the 5-day treatment regimen did not include mucosal thickening of >or=5 mm because it was believed that improvement in mucosal thickening might not be reliably measurable at the 5-day time point. All patients received garenoxacin 400 mg QD for 5 or 10 days. Maxillary sinus needle aspiration for Gram stain, routine culture, and susceptibility testing were performed before treatment, and, if clinically indicated, during and after treatment. Bacteriologic eradication (negative culture on repeat sinus aspiration) and cure rates (complete resolution of all signs and symptoms) were assessed at a test-of-cure visit 5 to 18 days after the end of treatment. The occurrence of adverse events was recorded by the investigators up to 30 days after the last administration of garenoxacin by questioning patients.

RESULTS

A total of 546 patients were enrolled and 543 were randomized (5-day cohort: mean age, 40 years; mean weight, 76 kg; 56% women; 10-day cohort: mean age, 41 years; mean weight, 77 kg; 58% women). Clinically evaluable patients included 253 in the 5-day cohort and 266 in the 10-day cohort. Cure rates were 93% (236/253; 95% CI, 89%-96%) and 91% (243/266; 95% CI, 87%-94%) for evaluable patients in the 5- and 10-day cohorts, respectively. Bacteriologic eradication rates in microbiologically evaluable patients were 94% in both cohorts (5 days, 204/217; 10 days, 182/193). Eradication rates in the 5- and 10-day cohorts were as follows: S pneumoniae, 94% (62/66) and 93% (39/42); H influenzae, 100% (30/30) and 93% (26/28); S aureus, 96% (23/24) and 91% (31/34); and M catarrhalis, 89% (8/9) and 86% (12/14). Of the 9 patients with acute bacterial sinusitis due to multidrug-resistant S pneumoniae, 8 achieved clinical cure with garenoxacin treatment. Adverse events (AEs) most frequently reported were diarrhea (<or=2%), nausea (2%-6%), headache (2%-6%), and dizziness (<or=2%). Two percent of patients withdrew because of an AE (allergic reaction, adverse gastrointestinal effects, dyspnea, dizziness, headache, or elevation in liver enzymes).

CONCLUSION

In this population of patients with signs and symptoms of acute maxillary sinusitis, oral garenoxacin 400 mg QD for 5 or 10 days eradicated 94% of bacterial pathogens associated with acute bacterial sinusitis in this population and appeared to be well tolerated in adults.

Penetration of garenoxacin into lung tissues and bone in subjects undergoing lung biopsy or resection

OBJECTIVE

Concentrations of garenoxacin in plasma and samples of lung parenchyma, bronchial mucosa, and bone were determined following single-dose administration.

RESEARCH DESIGN AND METHODS

Open-label, non-randomized study in which subjects undergoing invasive lung biopsy or resection were given a single 600-mg oral dose of garenoxacin. Lung parenchyma, and, if possible, bronchial mucosa and bone (i.e., flat bone with sinus mucosa or long bone from the lower legs) samples and corresponding plasma samples were obtained 2-4, 4-6, 10-12, or 20-24 h post-dose. Garenoxacin concentrations were measured using validated liquid chromatography with dual mass spectrometry. Safety was also assessed.

RESULTS

Twenty-seven subjects enrolled and completed the study. Garenoxacin plasma concentrations (mean +/- standard deviation) during the 24-h period ranged from 1.9 +/- 1 to 7.4 +/- 3 mug/mL. Garenoxacin concentrations in lung tissue (15.2 +/- 9 mug/g) peaked at 4-6 h and decreased to 3.7 +/- 3 mug/g at 20-24 h. Mean ratios between bronchial mucosa and plasma ranged from 0.82 to 0.99 over a 24-h period. At 12 h, the mean ratio between bone and plasma was 0.56. Garenoxacin concentrations in lung tissue exceeded the MIC(90) for common respiratory pathogens by at least 61-fold. Garenoxacin was safe and well tolerated. Forty-five adverse events were reported by 26 subjects; none were determined to be attributable to garenoxacin by the investigators. Most of the adverse events were mild to moderate in severity.

CONCLUSIONS

Garenoxacin achieved 24-h concentrations in pulmonary tissues that exceeded the MIC(90) for common respiratory pathogens. A controlled study involving a larger number of lung and bone tissue samples is needed to further confirm these findings.

Effect of an Aluminum- and Magnesium-Containing Antacid on the Bioavailability of Garenoxacin in Healthy Volunteers

STUDY OBJECTIVE

To evaluate the effect of an aluminum- and magnesium-containing antacid (Al-Mg antacid), which contains a high concentration of cations, on the pharmacokinetics of garenoxacin.

DESIGN

Prospective, randomized, open-label, control-balanced, residual-effects-design study.

SETTING

Pharmaceutical company-affiliated study clinic.

SUBJECTS

Twenty healthy volunteers who were garenoxacin naïve.

INTERVENTION

Subjects were randomly assigned to receive three of six oral treatments, each separated by a 7-day washout period: garenoxacin 600 mg administered alone, with concomitant Al-Mg antacid, 2 or 4 hours before Al-Mg antacid, or 2 or 4 hours after Al-Mg antacid. The Al-Mg antacid dose was 20 ml, which contained aluminum hydroxide 900 mg and magnesium hydroxide 800 mg.

MEASUREMENTS AND MAIN RESULTS

The pharmacokinetics and safety of garenoxacin were assessed. For each treatment, serial blood samples for pharmacokinetic analysis of garenoxacin were collected before and up to 72 hours after garenoxacin dosing. Absence of effect of Al-Mg antacid on garenoxacin area under the concentration-time curve from time zero extrapolated to infinity (AUC(0-infinity)) and maximum observed plasma concentration (C(max)) were concluded if the 90% confidence interval of the adjusted geometric mean ratios with and without the antacid were contained within 0.80-1.25 and 0.70-1.43, respectively. Exposure to garenoxacin measured by AUC(0-infinity), a parameter well correlated with efficacy, was reduced by 58% when coadministered with Al-Mg antacid and reduced by 22% and 16% when administered 2 and 4 hours after the antacid, respectively. Administration of garenoxacin 4 hours before Al-Mg antacid had no effect on AUC(0-infinity) or C(max) of garenoxacin, whereas administration 2 hours before the antacid resulted in a nonclinically relevant (12%) reduction in AUC(0-infinity) of garenoxacin.

CONCLUSION

Exposure to garenoxacin was significantly decreased when garenoxacin was coadministered with Al-Mg antacid or within 2 hours after the antacid. The magnitude of the changes in garenoxacin exposure suggests that garenoxacin should be administered at least 2 hours before or 4 hours after administration of Al-Mg antacid or other cation-containing products.

Activity of garenoxacin, an investigational des-F(6)-quinolone, tested against pathogens from community-acquired respiratory tract infections, including those with elevated or resistant-level fluoroquinolone MIC values

Garenoxacin, a novel des-F(6)-quinolone, was tested against 40423 pathogenic isolates associated with community-acquired respiratory tract infections (CA-RTIs). The strains included Streptococcus pneumoniae (18887), Haemophilus influenzae (15555), and Moraxella catarrhalis (5981), each isolated from a significant infection monitored by the SENTRY Antimicrobial Surveillance Program (1999-2005; North America, Latin America, and Europe). All tests were performed by reference broth microdilution methods for garenoxacin and 19 comparison agents. The garenoxacin MIC(90) and percentage (%) of strains inhibited at < or =1 microg/mL (proposed susceptible breakpoint) were S. pneumoniae (0.06 microg/mL, >99.9% susceptible), H. influenzae (< or =0.03 microg/mL, >99.9%), and M. catarrhalis (< or =0.03 microg/mL, 100.0%). The garenoxacin potency versus the pneumococci was 16- to 32-fold greater than levofloxacin or ciprofloxacin and 2-fold superior to moxifloxacin (MIC(90), 0.12 microg/mL). Resistances to other classes of antimicrobials did not adversely influence garenoxacin MIC results. Ciprofloxacin- or levofloxacin-resistant (MIC, > or =4 microg/mL) S. pneumoniae had higher garenoxacin MIC(90) values (1 microg/mL), but 90.6% to 97.5% of strains remained susceptible. Strains of all 3 monitored pathogens with mutations in the quinolone resistance determining region (QRDR) had higher garenoxacin MIC results, with > or =3 to 4 QRDR mutations required to elevate garenoxacin MIC values to > or =2 microg/mL. In conclusion, garenoxacin possesses a potent activity against pneumococci, H. influenzae, and M. catarrhalis strains worldwide, at a level significantly greater than the available tested agents in the fluoroquinolone class (ciprofloxacin, levofloxacin, and moxifloxacin). Only 13 and 4 isolates (0.07% and 0.03%) of S. pneumoniae and H. influenzae, respectively, had a garenoxacin MIC at > or =2 microg/mL, thus, making this new "respiratory antipneumococcal" quinolone an attractive candidate for the therapy of contemporary CA-RTI (bronchitis, pneumonia, and sinusitis).

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.

Garenoxacin pharmacokinetics in subjects with renal impairment

OBJECTIVE

This open-label, parallel-group study determined the pharmacokinetics of garenoxacin in subjects with severe renal impairment, including subjects maintained on dialysis.

RESEARCH DESIGN AND METHODS

Subjects were assigned to one of four groups according to their underlying renal function: creatinine clearance (CL(cr)) > 80 mL/min, CL(cr) < 30 mL/min, hemodialysis (HD), and continuous ambulatory peritoneal dialysis (CAPD). Subjects received a single oral 600-mg dose of garenoxacin. Administration of garenoxacin to subjects receiving hemodialysis was completed in two phases separated by 14 days: 3 h before HD (phase 1) and immediately after HD (phase 2).

MAIN OUTCOME MEASURES

Plasma and urine or dialysate samples were analyzed for garenoxacin, and single-dose pharmacokinetic parameters were estimated. Safety was assessed.

RESULTS

Twenty-five subjects received garenoxacin. Compared with healthy controls, garenoxacin area under the concentration-time curve (AUC) and maximum plasma concentration were increased by 51% and lowered by 20%, respectively, in subjects with severe renal impairment. The terminal half-life was prolonged in subjects with severe renal impairment compared with healthy controls (26.5 +/- 7 h vs 14.4 +/- 3 h, respectively). In subjects receiving HD or CAPD, removal of garenoxacin from systemic circulation was relatively inefficient (HD, 1.5-11.5%; CAPD, 3%), suggesting no need for a supplemental dose of garenoxacin after dialysis. Garenoxacin was well tolerated.

CONCLUSIONS

Based on the broad therapeutic index of garenoxacin, the effects of renal impairment on garenoxacin exposure are not considered clinically significant. There was a modest increase in AUC in subjects with severe renal impairment and the magnitude of the changes was not considered clinically relevant.

The antimicrobial armamentarium: evaluating current and future treatment options

The development and introduction of new antibiotics has, unfortunately, not kept pace with the development of bacterial resistance, and the need for new agents is becoming acute. Although some currently marketed agents remain valuable tools in the treatment of infectious diseases, few new drugs have reached the market in the last decade. In recent years, antibiotics with activity against certain problematic resistant bacteria such as methicillin-resistant Staphylococcus aureus, including linezolid and daptomycin, have been approved for clinical practice. Recently, tigecycline, a minocycline derivative, received approval by the United States Food and Drug Administration for treatment of complicated skin and skin structure and intraabdominal infections; the agent is also active against a variety of multidrug-resistant bacteria. Of the other agents in phase III development, ceftobiprole--a cephalosporin, and faropenem and doripenem--both carbapenems, have wide antibacterial spectra. Antimicrobial agents in the pipeline with marked gram-positive activity include dalbavancin, telavancin, and oritavancin.

Bactericidal activity of garenoxacin tested by kill-curve methodology against wild type and QRDR mutant strains of Streptococcus pneumoniae

Kill-curve bactericidal assays over 24 hours were determined for garenoxacin, a novel des-F(6) quinolone, and levofloxacin at achievable serum drug concentrations ranging from 2 to 8 microg/mL. Tested strains included 4 wild type and 2 target quinolone resistance-determining region (QRDR) mutant Streptococcus pneumoniae. Garenoxacin was 16-fold to 32-fold more active than levofloxacin, and mutant strains (3 QRDR sites) had garenoxacin minimum inhibitory concentration (MIC) values at 1 microg/mL (levofloxacin MIC >32 microg/mL, resistant), but equal to the levofloxacin potency against wild type strains. Garenoxacin killed mutant pneumococci with comparable rapidity, as did levofloxacin versus strains without target alterations. Garenoxacin appears to be a widely usable and highly active agent against S. pneumoniae resistant to other quinolones such as levofloxacin.

In vitro activities of garenoxacin and levofloxacin against Chlamydia pneumoniae are not affected by presence of Mycoplasma DNA

We studied 20 Chlamydia pneumoniae isolates obtained from respiratory sites and atheroma tissue of patients from various geographic areas to determine the susceptibilities of these isolates to a new des-fluoroquinolone, garenoxacin, and to levofloxacin. In addition, we assessed the cultures with these isolates by PCR for the presence or absence of Mycoplasma sp. DNA. Both the MIC at which 90% of isolates are inhibited (MIC(90)) and the minimal bactericidal concentration at which 90% of isolates are killed (MBC(90)) for garenoxacin were 0.06 microg/ml, and both the MIC(90) and the MBC(90) for levofloxacin were 2.0 microg/ml. The activity of garenoxacin against C. pneumoniae was 32-fold greater than that of levofloxacin. Mycoplasma sp. DNA was detected by PCR in 17 of 20 cultures. Mycoplasma amplicons from five Mycoplasma DNA-positive C. pneumoniae cultures were sequenced and found to represent four Mycoplasma species. Our data demonstrate that C. pneumoniae cultures frequently contain Mycoplasma DNA and that its presence in C. pneumoniae cultures does not appear to affect the susceptibility results for the two fluoroquinolones that we tested.

Comparison of Streptococcus pneumoniae and Haemophilus influenzae susceptibilities from community-acquired respiratory tract infections and hospitalized patients with pneumonia: five-year results for the SENTRY Antimicrobial Surveillance Program

The SENTRY Antimicrobial Surveillance Program has been monitoring the activity of commonly prescribed and novel antimicrobial agents on a global scale from 1997 to the present. Specific objectives have documented the key resistance rates among pathogens from both patients hospitalized with pneumonia and those diagnosed with community-acquired pneumonia. Hemophilus influenzae and Streptococcus pneumoniae are common pathogens in both of these patient populations and the susceptibility profiles for these two species were compared to distinguish potential differences that may be evident in North American surveillance (1997-2001). A total of 6,515 isolates of S. pneumoniae and 6,726 H. influenzae strains were tested using reference broth microdilution methods at a monitoring center. Ampicillin resistance was approximately 25% among H. influenzae isolates and did not significantly differ between strains from community-acquired infections or hospitalized patients. beta-lactamase-negative ampicillin resistant strains and fluoroquinolone refractory strains were rare (0.3 and </= 0.2%, respectively) and the former only detected among hospitalized patients. Macrolide-resistant H. influenzae was most prevalent in hospitalized patients with pneumonia (24.4% for clarithromycin). In contrast, H. influenzae isolates from community-acquired infections were less susceptible (78.6-81.7%) to trimethoprim/sulfamethoxazole, but very susceptible to fluoroquinolones (99.9-100.0%). The community-acquired S. pneumoniae isolates were generally more resistant to penicillin (16.7%) and other beta-lactams compared to those from hospitalized patients (12.1%), and were also much more resistant to trimethoprim/sulfamethoxazole (25.0%) compared to inpatient isolates (6.7%). In contrast, isolates with reduced fluoroquinolone susceptibility or resistance were more common among hospitalized patients (ciprofloxacin resistance at 4.0%) and increased over the five monitored years. It is evident from this longitudinal study that some antimicrobial agents are becoming less efficacious against common respiratory tract pathogens depending on the clinical setting and surveillance of resistance appears to be a prudent practice.