A comparative In vitro surveillance study of gemifloxacin activities against 2,632 recent Streptococcus pneumoniae isolates from across Europe, North America, and South America. The Gemifloxacin Surveillance Study Research Group

Female Asthmatic Patients Have Higher Risk to Develop Gemifloxacin-Associated Skin Rash, Highlighting Unique Delayed Onset Characteristics

Gemifloxacin is a common oral antibiotic for lower respiratory tract infection worldwide. We noticed an uncommon delayed onset skin rash in patients who received Gemifloxacin. Therefore, we retrospectively reviewed all patients who received Gemifloxacin from 1 January 2011 to 31 May 2016 in a university-affiliated hospital in Taiwan. A total of 1358 patients were enrolled, of whom 36 (2.65%) had skin eruptions. The female patients had a significantly higher odds ratio (OR) 2.24 (95% confidence interval (CI) 1.11–4.53, p = 0.021) of having skin eruptions. A history of asthma was also a significant risk factor (OR 2.04, 95% CI = 1.01–4.14, p = 0.043). Female asthmatic patients had the highest risk of skin eruptions (10/129, 7.2%) with an adjusted OR up to 4.45 (95% CI = 1.81–10.93, p < 0.001) compared to male and non-asthmatic patients. Of note, up to 58.3% (21/36) of the patients experienced a skin rash after they had completed and stopped Gemifloxacin. The median onset time was on the second day (ranging one to five days) after completing treatment. We reported that female asthmatic patients have the highest risk of Gemifloxacin-associated skin eruptions in Asia and that they highlighted a unique delayed onset skin rash.

Clarithromycin Extended-Release Tablet

Clarithromycin is an orally active, advanced-generation macrolide that has been reformulated as an extended-release tablet (Biaxin) XL Filmtab allowing convenient once-daily administration. The reformulation is intended to improve patient compliance and the tolerability of the drug. Although maximum plasma clarithromycin concentrations are lower and reached later with the extended-release tablets than with the immediate-release tablets, the two formulations are bioequivalent with respect to the area under the plasma concentration-time curve. Bioequivalence is also achieved between the formulations for the microbiologically active metabolite, 14-hydroxy-clarithromycin. Two randomized trials in patients with acute exacerbations of chronic bronchitis (AECB) showed that a 7-day course of clarithromycin extended-release 1000 mg once daily produced clinical cure rates of 83% and 85% and bacteriologic cure rates of 86% and 92% at the test-of-cure study visit. Similar rates of cure were achieved with a 7-day course of twice-daily clarithromycin immediate-release and with a 10-day course of twice-daily amoxicillin/clavulanic acid.A 7-day course of clarithromycin extended-release 1000 mg once daily produced clinical and bacteriologic cure rates of 88% and 86%, respectively, in patients with community-acquired pneumonia (CAP). Similar cure rates were achieved in recipients of once-daily levofloxacin in the same trial. In patients with acute maxillary sinusitis, a 14-day course of either once-daily clarithromycin extended-release or twice-daily clarithromycin immediate-release produced statistically equivalent clinical cure rates of 85% and 79%, respectively. Both treatment groups achieved similar rates of radiographic success and resolution of sinusitis. Recent results indicate that clarithromycin extended-release 500 mg once daily for 5 days is also effective in the treatment of patients with streptococcal pharyngitis/tonsillitis and in the treatment of AECB. The most frequently reported drug-related events with clarithromycin extended-release were abnormal taste (7% incidence), diarrhea (6%) and nausea (3%). Most adverse drug reactions were of a mild and transient nature. In comparative clinical trials, clarithromycin extended-release had an improved gastrointestinal tolerability profile compared with the immediate-release formulation. In addition, clarithromycin extended-release was better tolerated than amoxicillin/clavulanic acid and as well tolerated as levofloxacin. Further studies are required to assess the cost-effectiveness ratio of clarithromycin relative to comparator antibacterial agents.

CONCLUSION

Clarithromycin extended-release is an effective treatment for AECB, CAP, acute maxillary sinusitis, and pharyngitis (although not approved for the latter in the US), and is administered in a convenient dosage regimen that has the potential to encourage good compliance. The reformulation modulates clarithromycin absorption kinetics thereby improving tolerability. Therefore, clarithromycin extended-release provides a useful option for the treatment of specific respiratory tract infections.

Comparative in vitro and bactericidal activities of telithromycin against penicillin-nonsusceptible, levofloxacin-resistant, and macrolide-resistant Streptococcus pneumoniae by time-kill methodology

Broth microdilution MICs were determined for 14 antimicrobial agents against 296 clinical, non-duplicate isolates of Streptococcus pneumoniae collected at Methodist Hospital (Indianapolis, Indiana, USA) from January 2001 to December 2003. Isolates were categorized as susceptible, intermediate, or resistant using Clinical and Laboratory Standards Institute breakpoints. Time-kill studies were performed to evaluate the bactericidal activity of telithromycin at 1, 2, 4, and 8x MIC against 10 penicillin-nonsusceptible, levofloxacin-resistant, and macrolide-resistant (7 M-phenotype, 3 MLS(B)-phenotype) strains. Bactericidal activity was defined as a >/=3-log(10) reduction in CFU/mL. The prevalence of resistance was highest for the macrolides (32%), followed by penicillin (16.2%), clindamycin (10.8%), amoxicillin+/-clavulanate (4.4%), levofloxacin (3.0%), gatifloxacin and moxifloxacin (2.4%), ceftriaxone and cefotaxime (2.0%), and gemifloxacin (1.4%). None of the isolates tested were resistant to telithromycin. At 24h, telithromycin was bactericidal for 0/10, 2/10, 7/10, and 7/10 isolates at 1x MIC, 2x MIC, 4x MIC, and 8x MIC, respectively. At 4-8x MIC, telithromycin was bactericidal for 7/7 M-phenotype isolates and 0/3 MLS(B)-phenotype isolates. For the MLS(B)-phenotype isolates, colony counts were decreased by 1.3-2.1log(10) colony-forming units/mL after 24h at 8x MIC. Overall, telithromycin was highly active against 296 isolates of S. pneumoniae from our institution and demonstrated bactericidal activity at clinically achievable concentrations for 7 of 10 penicillin-nonsusceptible, levofloxacin-resistant, and macrolide-resistant S. pneumoniae. However, telithromycin was bacteriostatic for the MLS(B)-phenotype isolates.

Surveillance of antibiotic resistance in non invasive clinical isolates of Streptococcus pneumoniae collected in Belgium during winters 2003 and 2004

A total of 391 and 424 non-invasive isolates of Streptococcus pneumoniae collected by 15 laboratories during the 2003 and 2004 survey were tested for their susceptibility by a microdilution technique following NCCLS recommendations. Insusceptibility rates (IR) in the two surveys (2003/2004) were as follows: penicillin 15.0/14.7% [8.4/6.4% Resistance (R)], ampicillin 17.4/14.6% (R 9.0/7.1%), amoxicillin +/- clavulanic acid 2.6/1.2 % (R 0/0%), cefaclor 14.3/14.1% (R 11.5/13.4%), cefuroxime 13.6/12.7% (R 10.5/11.8%), cefuroxime-axetil 10.5/11.8% (R 10.0/9.2%) (breakpoints based on 250 mg), cefotaxime 4.9/6.2% (R 1.3/2.4%), ceftazidime NotTested (NT)/6.4 (R NT/2.6%), cefepime NT/6.4 (R NT/2.6%), imipenem 7.7/8.9 % (R 1.8/1.4%), ertapenem 0.8/NT% (R O/NT%), ciprofloxacin 13.8/9.0% (R 4.3/2.4%), levofloxacin 3.3/2.8% (R 1.5/0.2%), moxifloxacin 0.6/0.2% (R 0.3/0%), ofloxacin 13.5/9.0% (R 4.3/2.4%), erythromycin 26.1/24.7% (R 25.3/24.5%), azithromycin 25.4/24.7% (R 24.6/24.5%), telithromycin 0.8/0.2% (R 0.5/0%), clindamycin 21.2/18.4% (R 19.2/17.7%) and tetracycline 32.3/22.1% (R 29.2/19.3%). There were only minor differences in resistance rates according to age, sample site, admission type (i.e. ambulatory, hospitalized or long-term care facility patients), gender and geographic origin. Overall, telithromycin (MIC50, MIC90 in 2003/2004: 0.015 microg/ml, 0.12 microg/ml/ 0.008,0.06 respectively), ertapenem (0.03; 0.25/NT), moxifloxacin (0.06; 0.25/0.06, 0.12), and amoxicillin +/- clavulanic acid (0.03; 0.25/0.015, 0.5) were the most active compounds in both surveys. In 2003, the most common resistance phenotype was isolated insusceptibility to tetracycline (10.5%) followed by combined insusceptibility to erythromycin and tetracycline (9.3%). Erythromycin-tetracycline resistance (10.4%) was the most common in 2004. Isolates showing resistance to an antibiotic were significantly more present in 2003 than in 2004 (50.4% versus 40.8%). In penicillin-insusceptible isolates, MICs of all beta-lactams were increased but cross-resistance between penicillin and other beta-lactams in the penicillin-insusceptible isolates was not complete. In the 2003 survey, most of these isolates remained fully susceptible to ertapenem (94.9%) and amoxicillin +/- clavulanic acid (83.1%). In the 2004 survey, 91.9% of the penicillin insusceptible isolates remained susceptible to amoxicillin +/- clavulanic acid. In both surveys, the most common serotypes in penicillin insusceptible isolates were 14, 23,19 and 9 (20.0%, 20.0%, 16.4% and 10.9% respectively in 2003; 41.6%, 11.7%, 15.0% and 18.3% respectively in 2004).

Gemifloxacin for the treatment of respiratory tract infections: in vitro susceptibility, pharmacokinetics and pharmacodynamics, clinical efficacy, and safety

Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent exhibiting potent activity against most gram-negative and gram-positive organisms, such as the important community-acquired respiratory pathogens Streptococcus pneumoniae (including multidrug-resistant S. pneumoniae), Haemophilus influenzae , and Moraxella catarrhalis . The agent's mechanism of action involves dual targeting of two essential bacterial enzymes: DNA gyrase and topoisomerase IV. Gemifloxacin was approved by the Food and Drug Administration in April 2003 for treatment of community-acquired pneumonia and acute bacterial exacerbation of chronic bronchitis. The drug has an oral bioavailability of approximately 71%. Approximately 20-35% of gemifloxacin is excreted unchanged in the urine after 24 hours. The elimination half-life of gemifloxacin is 6-8 hours in patients with normal renal function, supporting once-daily dosing. The 24-hour free-drug area under the plasma concentration-time curve:minimum inhibitory concentration ratio (fAUC(0-24):MIC) associated with efficacy, based on results from in vitro and animal models of infection, is approximately 30. With a mean fAUC(0-24) of approximately 3 microg*hour/ml (35% of total AUC(0-24) of 8.4) and a median S. pneumoniae MIC for 90% of tested strains of 0.03, a fAUC(0-24):MIC ratio of 100 would be expected after standard dosing (320 mg once/day). In clinical studies involving both hospitalized and outpatient populations, gemifloxacin has been highly effective in the treatment of community-acquired pneumonia and acute exacerbation of chronic bronchitis. Clinical success rates ranged from 93.9-95.9% in patients with community-acquired pneumonia and 96.1-97.5% in those with acute exacerbation of chronic bronchitis. Gemifloxacin is well tolerated; the frequency of adverse events with this agent is low. Most adverse events are mild-to-moderate in severity, with diarrhea (< 4%), nausea and rash (< 3%), and headache (< 2%) most commonly reported. Drug interactions with gemifloxacin are not common, although absorption is greatly reduced when given with divalent and trivalent cation-containing compounds, such as antacids. Due to its potent activity against many common gram-positive and gram-negative respiratory pathogens, its proven clinical efficacy, and its favorable safety profile, gemifloxacin is a highly effective empiric treatment for community-acquired lower respiratory tract infections.

Assessment of pharmacokinetic-pharmacodynamic target attainment of gemifloxacin against Streptococcus pneumoniae

The treatment of community-acquired respiratory tract infections has been complicated by the emergence of multidrug-resistant Streptococcus pneumoniae. Although traditionally rare, a growing concern for fluoroquinolone-resistant pneumococci has surfaced. More pharmacodynamically potent antimicrobial agents are clearly needed, as the use of such agents may further optimize clinical and microbiological outcomes for patients and slow the emergence of fluoroquinolone resistance. For fluoroquinolones, the ratio of the 24-h area under the concentration-time curve of the agent to the minimum inhibitory concentration of the agent against the pathogen for the fraction of unbound drug is the major pharmacokinetic-pharmacodynamic (PK-PD) measure correlating with efficacy in nonclinical models and infected patients. A 2500-patient Monte Carlo simulation, utilizing a patient-population pharmacokinetic model derived from phase 3 registration trials and the minimum inhibitory concentration distribution for gemifloxacin against 3117 clinical strains of S. pneumoniae, was carried out to estimate the probability of gemifloxacin attaining exposures associated with efficacy. The overall probability PK-PD target attainment for gemifloxacin was greater than 0.99. Gemifloxacin is among the most pharmacodynamically potent fluoroquinolones and is more potent than ciprofloxacin, ofloxacin, and levofloxacin. Preferential use of pharmacodynamically potent agents over other alternatives may lead to improved clinical outcomes and decreased selection of fluoroquinolone-resistant pneumococci.

Gemifloxacin: a new fluoroquinolone

Gemifloxacin is a dual targeted fluoroquinolone with potent in vitro activity against Gram-positive, -negative and atypical human pathogens--pathogens considered to be important causes of community-acquired respiratory tract infections. Gemifloxacin demonstrates impressive minimal inhibitory concentrations (MIC 90 ) values against clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Chlamydia pneumoniae and Legionella spp., with MIC 90 values reported to be 0.016-0.06, < 0.0008-0.06, 0.008-0.3, 0.25, 0.125 and 0.016-0.07 microg/ml, respectively. Gemifloxacin is also active in vitro against a broad range of Gram-negative bacilli with MIC 90 values against the Enterobacteriaceae in the range of 0.016 to > 16 microg/ml ( Escherichia coli and Providencia stuartii, respectively), with the majority of the genus having MIC 90 drug concentrations < 0.5 microg/ml. The in vitro activity of gemifloxacin against anaerobic organisms is variable. The MIC values for gemifloxacin are not affected by beta-lactamase production nor by penicillin or macrolide resistance in S. pneumoniae. Gemifloxacin is approved by the FDA to be clinically efficacious against multi-drug resistant S. pneumoniae. The pharmacokinetics of gemifloxacin are such that the drug can be administered orally once-daily to yield or achieve sustainable drug concentrations exceeding the MIC values of clinically important organisms. Gemifloxacin has been shown to target both DNA gyrase (preferred target) and topoisomerase IV (secondary target) - enzymes critical for DNA replication and organism survival - against clinical isolates of S. pneumoniae. This dual targeting activity is thought to be important for reducing the likelihood for selecting for quinolone resistance. Gemifloxacin has been investigated and approved for therapy in patients with community-acquired pneumonia (CAP) and acute exacerbations of chronic bronchitis. In one study, more patients receiving gemifloxacin compared to clarithromycin remained free of exacerbations for longer periods of time (p < 0.016) and gemifloxacin had a shorter time to eradication of H. influenzae than did clarithromycin (p < 0.02). From efficacy studies, gemifloxacin was found to have an adverse profile that was comparable with other compounds. The most frequent side effects were diarrhoea, abdominal pain and headache. Gemifloxacin is a welcomed addition to currently available agents for the treatment of community-acquired lower respiratory tract infections. Other potential indications appear to be within the spectrum of this compound.

Antimicrobial susceptibility of community-acquired respiratory tract pathogens in the UK during 2002/3 determined locally and centrally by BSAC methods

OBJECTIVES

To determine the antimicrobial susceptibility of Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae causing community-acquired lower respiratory tract infection in the UK during 2002/2003 and to compare susceptibilities determined locally by disc diffusion with agar dilution MICs determined at a central laboratory.

METHODS

H. influenzae, M. catarrhalis and S. pneumoniae were isolated in 30 laboratories and susceptibility determined locally by the BSAC standardized disc diffusion method. At a central laboratory, isolates were re-identified, tested for beta-lactamase production (H. influenzae and M. catarrhalis only) and MICs determined using the BSAC agar dilution method.

RESULTS

Five hundred and eighty-one H. influenzae, 269 M. catarrhalis and 519 S. pneumoniae were collected. Over 93% of M. catarrhalis and nearly 15% of H. influenzae were beta-lactamase positive rendering these sub-populations resistant to aminopenicillins. Overall, the antibacterial susceptibility rates for the isolates were high. However, macrolides showed poor activity against H. influenzae (0.86-1.38% susceptible by disc or MIC methods) and, compared with other antimicrobials, against S. pneumoniae (approximately 88% susceptible). Between 84% and 95% of H. influenzae, M. catarrhalis and S. pneumoniae were susceptible to cefuroxime but all isolates were susceptible to cefotaxime. Eighty-five percent of H. influenzae were susceptible to trimethoprim. The fluoroquinolones were very active against the isolates, with moxifloxacin showing lower MICs than levofloxacin against S. pneumoniae. Susceptibility determined locally by disc diffusion was in general agreement with that determined centrally by agar dilution MIC testing. However, there was one inconsistency with H. influenzae where disc diffusion indicated 22.9% and 46.8% resistance to clarithromycin and erythromycin, respectively but by MIC, only 0.9% and 6.9% were resistant, respectively.

CONCLUSIONS

Rates of resistance within community-acquired respiratory tract isolates were relatively low in the UK, in agreement with other studies. Moxifloxacin was the only antibacterial with over 99% isolates susceptible for each of the three pathogens investigated where breakpoints are available. The comparison between disc susceptibility testing and MIC determination using BSAC methods indicated generally good correlation but has highlighted a methodological problem with macrolides against H. influenzae in particular.

Antimicrobial selection for community-acquired lower respiratory tract infections in the 21st century: a review of gemifloxacin

Community-acquired lower respiratory tract infections (LRTIs) are more prevalent in the elderly than in children and younger adults and form a significant proportion of all consultations and hospital admissions in this older age group. Furthermore, in a world of increasing life expectancy the trend seems unlikely to be reversed. Antimicrobial treatment of community-acquired pneumonia (CAP) must cover Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, and in many circumstances should also cover the intracellular (atypical) pathogens. In contrast, acute exacerbations of chronic bronchitis (AECB) are mainly associated with H. influenzae and S. pneumoniae and not with atypical bacteria: in severe cases, other Gram-negative bacteria may be involved. Frequently in LRTIs, the aetiology of the infection cannot be identified from the laboratory specimens and treatment has to be empirical. In such situations it is important to not only to use an antibiotic that covers all likely organisms, but also one that has good activity against these organisms given the local resistance patterns. Gemifloxacin is a new quinolone antibiotic that targets pneumococcal DNA gyrase and topoisomerase IV and is highly active against S. pneumoniae including penicillin-, macrolide- and many ciprofloxacin-resistant strains, as well as H. influenzae and the atypical pathogens. In clinical trials in CAP and AECB, gemifloxacin has been shown to be as effective a range of comparators and demonstrated an adverse event profile that was in line with the comparator agents. In one long-term study in AECB significantly more patients receiving gemifloxacin than clarithromycin remained free of recurrence after 26 weeks. The improved potency, broad spectrum of activity and proven clinical and bacteriological efficacy and safety profile should make it a useful agent in the 21st century battle against community-acquired LRTIs.

Gemifloxacin: a new fluoroquinolone approved for treatment of respiratory infections

OBJECTIVE

To evaluate the microbiology, pharmacokinetic parameters, drug interactions, and results of the available clinical trials of gemifloxacin for the treatment of community-acquired pneumonia (CAP) and acute exacerbation of chronic bronchitis (AECB).

DATA SOURCES

MEDLINE (1966-September 2003) was searched for primary and review articles. Data from the manufacturer were also included. Key words included adverse effects, clinical trials, drug interactions, gemifloxacin, and pharmacokinetic parameters.

STUDY SELECTION AND DATA EXTRACTION

All articles and product labeling concerning gemifloxacin, a fluoroquinolone antibiotic recently approved by the Food and Drug Administration for treatment of CAP and AECB, were included for review.

DATA SYNTHESIS

Compared with currently available fluoroquinolones, gemifloxacin demonstrated improved in vitro activity against Streptococcus pneumoniae (minimum inhibitory concentration for 90% eradication 0.03 microg/mL) and similar activity against gram-negative respiratory pathogens (Haemophilus influenzae, Moraxella catarrhalis) and atypical pathogens such as Chlamydia pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae. Gemifloxacin, consistent with other available fluoroquinolones, has insufficient activity against methicillin-resistant Staphylococcus aureus to allow clinical use for such infections. Gemifloxacin has adequate bioavailability and a favorable drug interaction profile. Gemifloxacin was comparable to commonly employed nonfluoroquinolone regimens for treatment of CAP and AECB, although the studies were designed to demonstrate equivalence. Gemifloxacin once daily for 5-7 days was well tolerated in controlled and uncontrolled clinical studies. Available clinical data, however, are insufficient to draw clinical or toxicologic distinctions between gemifloxacin and other fluoroquinolones.

CONCLUSIONS

Gemifloxacin may be a suitable choice for empiric treatment of CAP or AECB. However, due to the significant history of fluoroquinolone-induced hepatic failure and dermatologic complications, the use of this drug should be closely monitored.

In vitro pharmacodynamic activity of gatifloxacin, gemifloxacin, moxifloxacin and levofloxacin against Streptococcus pneumoniae containing specific mutations in DNA gyrase and topoisomerase IV

An in vitro pharmacodynatnic modeling apparatus (PDMA) generated specific bacterial kill profiles for single-dose regimens of gatifloxacin (GT), gemifloxacin (GM), moxifloxacin (MX) and levofloxacin (LV) against isolates of Streptococcus pneumoniae with specific QRDR profiles: SP-WT (no modifications); SP-C (changes in parC); and SP-AC (changes in both parC and gyrA). No differences in 3-log reduction time or total log reduction were observed among the four agents for SP-WT; however, LV failed to achieve a 3-log reduction in SP-C and SP-AC, and total log reduction after 12 hrs was minimal compared to the other agents. GM and MX required less time for 3-log reduction of SP-AC compared to GT, but total log reductions in SP-AC were similar among the three newer quinolone agents (GM > MX > GT). The study isolates with QRDR modifications greatly reduced LV activity. GM and MX maintained the greatest degree of activity against all study isolates and their activity was not adversely influenced by the genetic modifications in SP-C and SP-AC. The dual targeting characteristic of GM was also assessed, but did not offer significant advantages relative to MX and GT.

Gemifloxacin Mesylate

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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.

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.

Oral gemifloxacin once daily for 5 days compared with sequential therapy with i.v. ceftriaxone/oral cefuroxime (maximum of 10 days) in the treatment of hospitalized patients with acute exacerbations of chronic bronchitis

In a randomized, open-label, controlled, multicentre study, the clinical and bacteriological efficacy, safety and tolerability of oral gemifloxacin (320 mg once daily, 5 days) was compared with sequential intravenous (i.v.) ceftriaxone (1 g once daily, maximum 3 days) followed by oral cefuroxime axetil (500 mg twice daily, maximum 7 days) in adult hospitalized patients with acute exacerbations of chronic bronchitis (AECB) (n = 274). The clinical success rates at follow-up (21-28 days post-therapy) in the clinical per-protocol population (the primary endpoint) were 86.8% (105/121) for gemifloxacin vs. 81.3% (91/112) for ceftriaxone/cefuroxime (treatment difference = 5.5,95% CI -3.9,14.9). The corresponding clinical results in the clinical intention-to-treat (ITT) population were 82.6% (114/138) vs. 72.1% (98/136), respectively (treatment difference = 10.5,95% CI 0.7, 20.4).Thus, gemifloxacin had significantly higher clinical success rates than ceftriaxone/cefuroxime. The median time to discharge was 9 days in the gemifloxacin group vs. 11 days in the ceftriaxone/cefuroxime group (P = 0.04, Wilcoxon test). At follow-up, 120/138 (87.0%) gemifloxacin-treated patients had been discharged from hospital, compared with 111/136 (81.6%) ceftriaxone/cefuroxime-treated patients in the clinical ITT population. Both treatments were generally well tolerated and there was no significant difference between the treatment groups in the incidence or type of adverse events reported. A 5-day course of oral gemifloxacin was shown by this study to be at least equivalent to sequential i.v. ceftriaxone/cefuroxime axetil (for up to 10 days) in patients with AECB who require hospital treatment.

Microbiology of newer fluoroquinolones: focus on respiratory pathogens

Community-acquired pneumonia, acute exacerbations of chronic bronchitis, and acute sinusitis are among the most common bacterial infections encountered in clinical practice. Pathogens frequently associated with these infections include Streptococcus pneumoniae, Hemophilus influenzae, Moraxella catarrhalis, Chlamydia pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae. Unfortunately, resistance to antimicrobials commonly used for the treatment of these infections is increasing, limiting the clinical efficacy of these agents. Fluoroquinolones offer several advantages over other classes of antimicrobials used for the treatment of community-acquired respiratory tract infections. In general, fluoroquinolones have excellent in vitro activity against common respiratory pathogens, including some drug-resistant strains of S. pneumoniae. Microbial resistance to the newer fluoroquinolones is relatively uncommon, currently occurring in approximately 1% of clinical isolates in North America. Fluoroquinolones currently in clinical development may offer additional benefits over the marketed agents because they maintain good potency against isolates of S. pneumoniae displaying resistance to older quinolones (i.e., ofloxacin or ciprofloxacin) and may have a lower potential to engender resistance. This article reviews the in vitro activity of several newer fluoroquinolones, including agents currently in clinical development, against common respiratory pathogens, including antimicrobial-resistant strains. The mechanisms and prevalence of resistance of beta-lactam antimicrobials, macrolides, and fluoroquinolones also are reviewed.

Oral gemifloxacin versus sequential therapy with intravenous ceftriaxone/oral cefuroxime with or without a macrolide in the treatment of patients hospitalized with community-acquired pneumonia: a randomized, open-label, multicenter study of clinical efficacy and tolerability

OBJECTIVE

This study aimed to compare the efficacy and safety of oral gemifloxacin, an enhanced-affinity quinolone, with sequential therapy with IV ceftriaxone followed by oral cefuroxime (with or without a macrolide) in patients hospitalized for community-acquired pneumonia (CAP).

METHODS

A randomized, open-label, multicenter study comprised adults hospitalized with a clinical and radiologic diagnosis of CAP. Patients were randomized 1:1 to receive either (1) oral gemifloxacin 320 mg once daily (7-14 days); or (2) IV ceftriaxone 2 g once daily (1-7 days) followed by oral cefuroxime 500 mg twice daily (1-13 days) for a total of < or = 14 days. Patients receiving ceftriaxone/cefuroxime were allowed concomitant macrolide treatment.

RESULTS

A total of 345 patients were randomized, of whom 341 received at least 1 dose of study medication (gemifloxacin, 169/172; ceftriaxone/cefuroxime, 172/173). Clinical success rates in the clinically evaluable (CE) population at follow-up (day 21-28 post-therapy), the primary end point, were 92.2% (107/116) for gemifloxacin and 93.4% (113/121) for ceftriaxone/cefuroxime (treatment difference, -1.15; 95% CI, -7.73 to 5.43). In patients in Fine risk classes IV and V, the clinical success rate was 87.0% (20/23) for gemifloxacin versus 83.3% (20/24) for ceftriaxone/cefuroxime. No difference in clinical response at follow-up was noted based on macrolide use. Bacteriologic success rates at follow-up in the bacteriologically evaluable (BE) population were 90.6% (58/64) for gemifloxacin and 87.3% (55/63) for ceftriaxone/cefuroxime (treatment difference 3.32; 95% CI, -7.57 to 14.21). The clinical success rate in bacteremic patients at follow-up (BE population) was 100.0%. Both treatments were generally well tolerated. The frequency and types of adverse events were similar between the 2 groups. The most common treatment-related adverse events with gemifloxacin were diarrhea, liver-function adverse events, and rash; with ceftriaxone/cefuroxime, they were diarrhea, elevated hepatic-enzyme activity, and moniliasis.

CONCLUSION

The clinical efficacy and tolerability of oral gemifloxacin 320 mg once daily were similar to those of IV ceftriaxone followed by oral cefuroxime (with or without a macrolide) in the treatment of adult patients hospitalized with moderate to severe CAP. Both treatments were effective in bacteremic patients and those at increased risk of mortality.

Penetration of topically administered ofloxacin and trimethoprim into aqueous humor

Ocular penetration of two topical antibiotics used to treat bacterial conjunctivitis was assessed in adult volunteers scheduled for cataract surgery. In this randomized, parallel-group study, patients instilled trimethoprim sulfate 0.1%/polymyxin B (n = 23) or ofloxacin 0.3% (n = 25) QID for 3 days, plus 4 instillations in the hour before surgery. Analysis of aqueous humor samples obtained during surgery showed a 2.4-fold greater concentration of ofloxacin over trimethoprim (1.135 micro g/ml vs 0.470 micro g/ml; P <.0001). The greater concentration of ofloxacin in ocular tissue coupled with its superior antibacterial activity profile supports its use as an alternative to trimethoprim/polymyxin B for treatment of bacterial conjunctivitis.

A comparison of gemifloxacin and clarithromycin in acute exacerbations of chronic bronchitis and long-term clinical outcomes

BACKGROUND

Gemifloxacin is an enhanced-affinity quinolone with potent activity against lower respiratory tract pathogens.

OBJECTIVE

The efficacy and safety of a 5-day course of gemifloxacin were compared with those of a standard 7-day regimen of clarithromycin in patients with an acute exacerbation of chronic bronchitis (AECB). The impact of treatment on the long-term (26 weeks) clinical outcome was also assessed.

METHODS

The acute phase of this randomized, double-blind study was performed in 93 centers in 7 countries. Adult patients (age >40 years) with a history of chronic bronchitis and an Anthonisen type 1 acute exacerbation (increased dyspnea, cough, and sputum purulence) were eligible. Patients receiving systemic steroids at a dose of >10 mg prednisone or the equivalent were excluded. Patients were randomized to receive gemifloxacin 320 mg once daily for 5 days or clarithromycin 500 mg twice daily for 7 days. Clinical and bacteriologic response rates were assessed at the end-of-therapy visit (days 8-12), the week 2-3 follow-up visit (days 13-24), and the week 4-5 follow-up visit (days 25-38). The long-term phase (26 weeks), which included US and Canadian participants only, evaluated the proportion of patients who remained free of a recurrence of AECB requiring additional antimicrobial therapy after resolution of the initial episode.

RESULTS

Seven hundred twelve patients were randomized to treatment, 351 to gemifloxacin and 361 to clarithromycin. The long-term study included 438 patients, 214 receiving gemifloxacin and 224 receiving clarithromycin. Clinical success rates at the 2-3 week follow-up visit were 85.4% for gemifloxacin and 84.6% for clarithromycin. Bacteriologic success rates were 86.7% for gemifloxacin and 73.1% for clarithromycin. Significantly more patients receiving gemifloxacin than clarithromycin remained free of AECB recurrences (71.0% vs 58.5%, respectively; P = 0.016). Both treatments were well tolerated.

CONCLUSIONS

In the acute treatment of Anthonisen type 1 AECB, a 5-day course of gemifloxacin was at least as effective as a 7-day regimen of clarithromycin. In this population, significantly more patients receiving gemifloxacin remained free of AECB recurrence after 26 weeks compared with those receiving clarithromycin.

Comparative in vitro activities of five quinolone antibiotics, including gemifloxacin, against clinical isolates

The in vitro activities of ciprofloxacin, ofloxacin, norfloxacin, levofloxacin and gemifloxacin against 343 clinical isolates were compared. Gemifloxacin showed the greatest activity, with MIC90 values as low as 0.03-0.25 mg/L against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, methicillin-susceptible Staphylococcus aureus and Klebsiella pneumoniae, while methicillin-resistant Staphylococcus aureus, Enterococcus spp., Pseudomonas spp., Acinetobacter spp., Escherichia coli and Enterobacter spp. strains exhibited low rates of susceptibility to all five fluoroquinolones.

Comparative in vitro activity of gemifloxacin against gram-positive and gram-negative clinical isolates in Argentina

The in vitro activity of gemifloxacin against 1,000 clinical isolates of 147 Streptococcus pneumoniae (115, penicilin susceptible; 26, intermediate penicillin-resistant and 6, penicillin-resistant), 127 Hemophilus influenzae (109, beta lactamasa non-producer; 18, beta lactamase producers), 95 Streptococcus pyogenes (6, azytromycin-resistant), 84 Moraxella catarrhalis (79, beta lactamase producers), 110 Staphilococcus aureus (89, methicillin-susceptible; 21, methicilin-resistant), 98 Eenterococcus faecalis and 339 Enterobacteriacea, (recovered from patients with respiratory tract infection; skin and soft tissue infection and urinary tract infection), was compared with the activities of four fluorquinolones and five other antimicrobial agents. Of the quinolones tested, gemifloxacin was the most potent against Streptococcus pneumoniae, including penicillin intermediate and resistant strains. Mic(90) values obtained for gemifloxacin, ciprofloxacin, ofloxacin, levofloxacin and trvafloxacin were 0.03, 2, 2, 1 and 0.25 mg/L respectively. Gemifloxacin was 16 fold more potent than ciprofloxacin against methicillin-susceptible Staphylococcus aureus and 32 fold more potent than ciprofloxacin against Streptococcus pyogenes. When tested against Hemophilus influenzae, Moraxella catarrhalis and Enterobacteriaceae, all the quinolones showed similar activity. Our results demonstrate that gemifloxacin has similar activity than the other quinolones tested against Gram-negative organisms and is considerably more potent against Gram-positive organisms.

Comparative in vitro activity of gemifloxacin, ciprofloxacin, levofloxacin and ofloxacin in a North American surveillance study

The in vitro activity of gemifloxacin, a new fluoroquinolone, was compared to three marketed fluoroquinolones; ciprofloxacin, levofloxacin and ofloxacin against over 4,000 recent clinical isolates covering 29 species isolated in the United States and Canada between 1997-1999. Based on MIC(90)s, gemifloxacin was the most potent fluoroquinolone tested against a majority of Gram-positive isolates: Streptococcus pneumoniae, penicillin resistant S. pneumoniae, macrolide resistant S. pneumoniae, ciprofloxacin non-susceptible (MIC > or = 4 microg/mL) S. pneumoniae, S. pyogenes, S. agalactiae, viridans streptococci, Enterococcus faecalis, methicillin susceptible Staphylococcus aureus, methicillin resistant S. aureus, S. epidermidis, S. hemolyticus, and S. saprophyticus. Against Enterobacteriaceae and aerobic non-Enterobacteriaceae Gram-negatives, gemifloxacin was usually comparable to ciprofloxacin and levofloxacin and more potent than ofloxacin for the following species: Citrobacter freundii, Enterobacter aerogenes, E. cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, P. vulgaris, Providencia stuartii, Serratia marcescens, Acinetobacter lwoffii, A. baumannii, Burkholderia cepacia, Haemophilus influenzae, H. parainfluenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. Gemifloxacin was generally 16-64 fold more potent than the other fluoroquinolones tested against Gram-positive organisms and retains excellent activity comparable with ciprofloxacin and levofloxacin against a majority of Gram-negative pathogens.