In vitro activity of CP-99,219, a new fluoroquinolone, against clinical isolates of gram-positive bacteria

Lipopolysaccharide and trovafloxacin coexposure in mice causes idiosyncrasy-like liver injury dependent on tumor necrosis factor-alpha

Idiosyncratic adverse drug reactions (IADRs) occur in a small subset of patients, are unrelated to the pharmacological action of the drug, and occur without an obvious relationship to dose or duration of drug exposure. The liver is often the target of these reactions. Why they occur is unknown. One possibility is that episodic inflammatory stress interacts with the drug to precipitate a toxic response. We set out to determine if lipopolysaccharide (LPS) renders mice sensitive to trovafloxacin (TVX), a fluoroquinolone antibiotic linked to idiosyncratic hepatotoxicity in humans and if the cytokine tumor necrosis factor-alpha (TNFalpha) is involved in the development of liver injury. Male mice were treated with a nontoxic dose of TVX followed 3 h later by a nonhepatotoxic dose of LPS. Coexposure to TVX and LPS led to a significant increase in liver injury as determined by plasma alanine aminotransferase activity and histopathological examination. In contrast, coexposure of mice to LPS and levofloxacin (LVX), a fluoroquinolone without liability for causing IADRs in humans, was not hepatotoxic. Measurements of TNFalpha concentration in the plasma revealed a significant, selective increase in TVX/LPS-treated mice at times prior to and at the onset of liver injury. Treatment with either pentoxifylline to inhibit TNFalpha transcription or etanercept to inhibit TNFalpha activity significantly reduced TVX/LPS-induced liver injury. The results suggest that the model in mice is able to distinguish between drugs with and without the propensity to cause idiosyncratic liver injury and that the hepatotoxicity is dependent on TNFalpha.

Effect of ethanol on fluoroquinolone efficacy in a rat model of pneumococcal pneumonia

This investigation compared the effect of ethanol on fluoroquinolone antibiotic efficacy and pharmacodynamics in an ethanol-fed rat model of pneumococcal pneumonia. Male Sprague-Dawley rats received a liquid diet containing 36% of total calories as ethanol. Paired controls (pair-fed controls) were fed a liquid diet without ethanol or received rat chow. Diets began 7 days before and continued for 10 days after transtracheal infections with 10 times the 50% lethal dose of type 3 Streptococcus pneumoniae. Beginning 18 h after infection, the rats received once daily subcutaneous phosphate-buffered saline, levofloxacin, moxifloxacin, or trovafloxacin at 50 or 100 mg/kg of body weight. White blood cell counts were determined, blood samples were collected for culture, and mortality was recorded. Additional rats were killed on day 5 for pharmacodynamic studies and quantitative cultures of bronchoalveolar lavage fluid. Bacteremia occurred by day 3 in 20 of 22 untreated rats. All 22 untreated rats died by day 9. Moxifloxacin treatment was effective in all diet groups at both the 50- and 100-mg/kg doses. In contrast, 50-mg/kg doses of levofloxacin and trovafloxacin improved survival in ethanol-fed rats but were ineffective in chow-fed rats. High-dose trovafloxacin at 100 mg/kg was associated with increased mortality in pair-fed rats. The free-fraction area under the concentration-time curve/MIC ratio exceeded 50 with all antibiotics in the ethanol group but dropped below 30 with levofloxacin and trovafloxacin in the pair- and chow-fed rats, with higher mortality. Achievement of adequate antibiotic-free fraction area under the concentration-time curve/MIC ratios helps overcome ethanol-induced immune defects induced in experimental pneumococcal pneumonia.

Effect of cirrhosis on antibiotic efficacy in a rat model of pneumococcal pneumonia

A rat model was used to study the effects of cirrhosis on antibiotic therapy of pneumococcal pneumonia. Cirrhotic and control male Sprague-Dawley rats were infected transtracheally with type 3 Streptococcus pneumoniae. Treatment began 18 h later with phosphate-buffered saline (PBS), azithromycin (50 mg/kg), trovafloxacin (50 mg/kg), or ceftriaxone (100 mg/kg) injected subcutaneously twice daily for 5 days. Antibiotic concentrations were measured by high-performance liquid chromatography. Azithromycin, trovafloxacin, and ceftriaxone were all equally effective at preventing mortality in both cirrhotic and normal rats. Free fraction area under the curve to minimum inhibitory concentration ratio (AUC/MIC) and maximum calculated serum concentration to MIC ratio (C(max)/MIC) and percent time that the serum concentration exceeded the MIC (%T > MIC) were greater for ceftriaxone compared with azithromycin or trovafloxacin. Azithromycin achieved higher concentrations in bronchoalveolar lavage fluid (BALF), epithelial lining fluid (ELF), and BAL white blood cells than ceftriaxone or trovafloxacin in cirrhotic rats. Macrolide, beta-lactam, or fluoroquinolone antibiotic efficacy in a pneumococcal pneumonia model does not appear to be affected by hepatic cirrhosis.

Minimal inhibitory concentrations and time-kill determination of moxifloxacin against aerobic and anaerobic isolates

Moxifloxacin is a new oral 8-methoxy-quinolone with a wide spectrum of activity against Gram-negative and anaerobic bacteria, atypical micro-organisms and multi-resistant Gram-positive bacteria. This study was designed to assess the in vitro activity of moxifloxacin against Gram-positive bacteria with different resistance patterns, anaerobes and atypical micro-organisms such as Chlamydia and Mycoplasma. Moxifloxacin had good activity against Streptococcus pneumoniae with all strains inhibited by < or =0.12 mg/l. The minimal inhibitory concentrations (MICs) of moxifloxacin for Streptococcus pyogenes and Streptococcus agalactiae ranged from 0.03 to 0.5 mg/l while those of ciprofloxacin were about two- to four-fold higher (MICs=0.12-1 mg/l). Moxifloxacin was poorly active against enterococci but its activity against Clostridium and Bacteroides spp. was in the same range as that of metronidazole and superior to that of clindamycin. Moxifloxacin was substantially more active than both ciprofloxacin and sparfloxacin against Chlamydia.

Community-acquired lower respiratory tract infections: etiology and treatment

The current therapy for community-acquired lower respiratory tract infections is often empiric, usually involving administration of a beta-lactam or macrolide. However, the increasing prevalence of antibiotic resistance in frequently isolated respiratory tract pathogens has complicated the antimicrobial selection process. This review will discuss the incidence of various respiratory pathogens, as well as update the clinician on the various antimicrobial alternatives available, with particular emphasis on the role of the newer fluoroquinolones in the treatment of acute exacerbations of chronic bronchitis and community-acquired pneumonia.

Successful trovafloxacin prophylaxis against experimental streptococcal aortic valve endocarditis

Single-dose trovafloxacin (15 mg/kg given intravenously [i.v.]) and ampicillin (40 mg/kg given i.v.) protected 38 and 33% of animals challenged with an ampicillin-tolerant strain of Streptococcus oralis, respectively. As a double-dose regimen, trovafloxacin afforded total protection (100%; P < 0.001 versus controls). Trovafloxacin is the first fluoroquinolone effective in preventing experimental streptococcal endocarditis.

Calibration of the disk diffusion test for trovafloxacin susceptibility testing of four anaerobic species

OBJECTIVES

To study trovafloxacin susceptibility among clinical isolates of four anaerobic bacterial species using minimum inhibitory concentrations (MIC) determinations, E test assays and disk diffusion test results and to calibrate the disk diffusion method for these species using single strain regression analysis (SRA).

METHODS

One-hundred and eighty-seven clinical isolates of four anaerobic bacterial species were included. Trovafloxacin MIC determinations were performed using the agar dilution technique and MIC estimations using the E test. The disk diffusion test was performed according to Swedish Reference Group for Antibiotics standardization. NCCLS limits for susceptibility categories were applied. SRA was performed using 1, 3, 10, 30, and 100 microg trovafloxacin disk contents and ATCC control strains. The regression lines obtained permitted the calculation of zone equivalents to MIC limits as well as an evaluation of various disk potencies.

RESULTS

Trovafloxacin susceptibility (S + I) was noted in 98.9, 100, 100, and 97% of Bacteroides fragilis, Bacteroides thetaiotaomicron, Clostridium perfringens, and Peptostreptococcus magnus strains, respectively, as judged by MIC determinations. Agar dilution and E test estimations gave the same results, but E test values were consistently lower than MIC values by the reference method. Regression lines calculated for the four species using SRA showed different equation constants indicating species-related differences. Interpretive zone diameter breakpoints were calculated for the four species and used for the interpretation of susceptibility.

CONCLUSIONS

The disk diffusion test was successfully calibrated for trovafloxacin susceptibility testing of four anaerobic species using single strain regression analysis, SRA. There was a good agreement between the results of MIC-tests and disk testing. Interpretive errors of type I are prone to occur among Bacteroides isolates and might require species-related MIC limits. SRA calculations permitted the testing of the effect of different disk potencies on inhibition zones produced at the interpretive MIC limits. Criteria for the selection of a minimal disk content showed that 5 microg trovafloxacin is sufficient, but a 10 microg disk will safeguard against residual laboratory variation without producing too large inhibition zones for very susceptible strains.

Plasmid curing effect of trovafloxacin

The effect of sub-inhibitory concentrations of trovafloxacin, a recently developed fluoroquinolone molecule, on the capability of Escherichia coli cells to maintain three different types of plasmids has been investigated by a number of approaches, including the quantification of the loss of plasmid-borne functions and of plasmid DNA by quantitative PCR. The results obtained demonstrate that at concentrations ranging from the MIC to 1/8 of the MIC, trovafloxacin induces a clear, albeit incomplete, 'episome-curing' effect which was observed with plasmids differing in copy number, size and nature of the replication origin of the episome. This effect was most likely not due to an alteration of DNA supercoiling.

Trovafloxacin concentrations in airway fluids of patients with severe community-acquired pneumonia

The penetration of trovafloxacin (TVA), 200 mg once daily, into the airways of 17 patients with severe pneumonia was studied. The mean (standard deviations are given in parentheses) steady-state TVA concentrations, 2 h after the last intake, were 3.1 (0.3) mg/liter in induced sputum (n = 8), 3.2 (1.1) mg/liter in bronchial secretions (n = 9), 3.2 (0.9) mg/liter in bronchoalveolar lavage fluid (n = 10), and 4.9 (1.4) mg/liter in epithelial lining fluid (n = 11).

Activity of newer fluoroquinolones in vitro against gram-positive bacteria

Several newer fluoroquinolones, which have been recently introduced or are under investigation, display substantially greater potency against gram-positive organisms than the older generation agents of this class. Nevertheless, for problem organisms including methicillin-resistant strains of Staphylococcus aureus and many Enterococcus faecium, concentrations of newer antimicrobials required to inhibit 90% of organisms in the collections studied remain above those that are projected to be achievable with clinical use. Nevertheless, enhanced potency of several newer quinolones may result in a favourable pharmacodynamic profile leading to improved outcomes against gram-positive infections and possibly to the delayed or diminished emergence of resistance to these agents.

Comparison of five beta-lactam antibiotics against common nosocomial pathogens using the time above MIC at different creatinine clearances

STUDY OBJECTIVE

To compare the time above the minimum inhibitory concentration (T>MIC) for five parenteral beta-lactam antibiotics against common nosocomial bacterial pathogens at different creatinine clearances (Clcr).

INTERVENTIONS

Serum concentration-time profiles were simulated for cefepime, ceftazidime, piperacillin, piperacillin-tazobactam, and imipenem at Clcr ranging from 120-30 ml/minute. The MIC data for 90% of organisms (MIC90) were collected for Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, Pseudomonas aeruginosa, and oxacillin-susceptible Staphylococcus aureus, and a weighted geometric mean MIC90 was calculated. The T>MIC was calculated as percentage of the dosing interval in which free concentrations exceeded the weighted geometric mean MIC90. A T>MIC of 70% or greater was considered desirable for all organisms except S. aureus (> or = 50%).

MEASUREMENTS AND MAIN RESULTS

Cefepime 2 g every 12 hours (Clcr > or = 70 ml/min) and every 24 hours (Clcr < or = 60 ml/min) achieved desirable T>MIC for all Enterobacteriaceae and S. aureus at every Clcr. Imipenem 0.5 g achieved desirable T>MIC for E. coli, K. pneumoniae, C. freundii, and S. aureus at every Clcr. However, imipenem T>MIC was less than 70% for the following regimens and organisms: S. marcescens 0.5 g every 6 hours (Clcr > or = 90 ml/min), E. aerogenes 0.5 g every 6 hours (Clcr > or = 80 ml/min), E. cloacae 0.5 g every 6 hours (Clcr > or = 100 ml/min), S. marcescens 0.5 g every 8 hours (Clcr 60-70 ml/min), E. cloacae 0.5 g every 8 hours (Clcr 60-70 ml/min), and E. aerogenes 0.5 g every 8 hours (Clcr 50-70 ml/min). Ceftazidime 2 g every 8 hours (Clcr 60-100 ml/min) and every 12 hours (Clcr 40-50 ml/min) achieved desirable T>MIC for E. coli, K. pneumoniae, S. marcescens, and S. aureus only. At every dose and Clcr, piperacillintazobactam achieved desirable T>MIC for S. aureus but not for any Enterobacteriaceae at Clcr > 50 ml/minute. Piperacillin did not achieve desirable T>MIC for any organism, and none of the beta-lactams attained a T>MIC of 70% or above for P. aeruginosa at any Clcr.

CONCLUSION

At every Clcr, cefepime achieved a desirable T>MIC for more nosocomial pathogens than any other beta-lactam evaluated. Based on pharmacodynamic data, cefepime is an appropriate empiric choice for treatment of nosocomial infections. However, when P. aeruginosa is a potential pathogen, empiric combination therapy should be considered.

Recent progress in novel macrolides, quinolones, and 2-pyridones to overcome bacterial resistance

Macrolides, such as clarithromycin and azithromycin, having good activity against pathogens such as Legionella, Chlamydia, Campylobacter spp, Branhamella spp, Pasteurella multocida and streptococci, have gained wide acceptance for the treatment of both upper and lower respiratory tracts, as well as cutaneous infections. Emergence of bacterial resistance, particularly in gram-positive bacteria, has been observed. Macrolide-resistant Streptococcus pneumoniae and S. pyogenes are found in France and many other countries, resulting in failure of therapy for pneumonia, pharyngitis, and skin infection. RU 004, HMR 3647, and TE 802 were reported to be active against these resistant strains. Research at Abbott produced several macrolide derivatives in the anhydrolide, tricyclic and tetracyclic ketolides as well as 6-O-alkyl ketolides series having potent activity against macrolide resistant S. pyogenes and S. pneumoniae. Research on streptogramins to overcome bacterial resistance in gram-positive bacteria has produced interesting compounds. Another class of antibacterial agent called quinolones is useful for the treatment of bacterial infections of respiratory tract, urinary tract, skin and soft tissues, as well as sexually transmitted diseases. Ciprofloxacin, the market leader, however, has low potency against anaerobes. Bacterial resistance ( such as Pseudomonas aeruginosa and methicillin- resistant Staphylococcus aureus ) to ciprofloxacin is increasing rapidly. Many quinolone compounds are being synthesized to address these drawbacks. The new quinolones currently under development are characterized by enhanced activities against streptococci, staphylococci, enterococci, and anaerobes. This presentation reviews the current research in the identification of agents to overcome the macrolide and quinolone resistance.

Double-blind comparison of trovafloxacin and doxycycline in the treatment of uncomplicated Chlamydial urethritis and cervicitis. Trovafloxacin Chlamydial Urethritis/Cervicitis Study Group

BACKGROUND

Chlamydia trachomatis is among the most common sexually transmitted bacteria worldwide. With excellent activity against C. trachomatis and Neisseria gonorrhoeae and prolonged elimination half-life allowing once-daily dosage, the fluoroquinolone trovafloxacin has potential advantages in the treatment of uncomplicated chlamydial infection.

GOAL OF THIS STUDY

This study compared the efficacy of trovafloxacin with that of doxycycline for the treatment of uncomplicated chlamydial infection.

STUDY DESIGN

In a double-blind, multicenter trial, trovafloxacin 200 mg was administered once daily for 5 days and doxycycline 100 mg was administered twice daily for 7 days to patients with uncomplicated chlamydial urethritis or cervicitis. Follow-up visits were conducted 10, 21, and 35 days after enrollment.

RESULTS

Of the 970 patients (403 men, 567 women) observed, 511 were microbiologically evaluable and 360 were clinically evaluable. C. trachomatis eradication rates in the trovafloxacin and doxycycline groups were equivalent in women (95% and 97%, respectively), but not in men (89% and 99%). Similarly, rates of clinical success (cure plus improvement) demonstrated equivalence of trovafloxacin and doxycycline in women (96% and 94%), but not in men (94% and 100%). The most frequent treatment-related adverse events were dizziness, nausea, and headache in patients given trovafloxacin, and nausea, vomiting, and headache in patients given doxycycline. Treatment-related discontinuations were comparable between the drug groups.

CONCLUSION

Trovafloxacin given once daily for 5 days was clinically and bacteriologically equivalent to doxycycline given twice daily for 7 days in women with uncomplicated chlamydial cervicitis. This equivalence was not demonstrated in men with uncomplicated chlamydial urethritis.

Activities of trovafloxacin compared with those of other fluoroquinolones against purified topoisomerases and gyrA and grlA mutants of Staphylococcus aureus

Frequencies of mutation to resistance with trovafloxacin and four other quinolones were determined with quinolone-susceptible Staphylococcus aureus RN4220 by a direct plating method. First-step mutants were selected less frequently with trovafloxacin (1.1 x 10(-10) at 2 to 4x the MIC) than with levofloxacin or ciprofloxacin (3.0 x 10(-7) to 3.0 x 10(-8) at 2 to 4x the MIC). Mutants with a change in GrlA (Ser80-->Phe or Tyr) were most commonly selected with trovafloxacin, ciprofloxacin, levofloxacin, or pefloxacin. First-step mutants were difficult to select with sparfloxacin; however, second-step mutants with mutations in gyrA were easily selected when a preexisting mutation in grlA was present. Against 29 S. aureus clinical isolates with known mutations in gyrA and/or grlA, trovafloxacin was the most active quinolone tested (MIC at which 50% of isolates are inhibited [MIC(50)] and MIC(90), 1 and 4 microg/ml, respectively); in comparison, MIC(50)s and MIC(90)s were 32 and 128, 16 and 32, 8 and 32, and 128 and 256 microg/ml for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin, respectively. Strains with a mutation in grlA only were generally susceptible to all of the quinolones tested. For mutants with changes in both grlA and gyrA MICs were higher and were generally above the susceptibility breakpoint for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin. Addition of reserpine (20 microg/ml) lowered the MICs only of ciprofloxacin fourfold or more for 18 of 29 clinical strains. Topoisomerase IV and DNA gyrase genes were cloned from S. aureus RN4220 and from two mutants with changes in GrlA (Ser80-->Phe and Glu84-->Lys). The enzymes were overexpressed in Escherichia coli GI724, purified, and used in DNA catalytic and cleavage assays that measured the relative potency of each quinolone. Trovafloxacin was at least five times more potent than ciprofloxacin, sparfloxacin, levofloxacin, or pefloxacin in stimulating topoisomerase IV-mediated DNA cleavage. While all of the quinolones were less potent in cleavage assays with the altered topoisomerase IV, trovafloxacin retained its greater potency relative to those of the other quinolones tested. The greater intrinsic potency of trovafloxacin against the lethal topoisomerase IV target in S. aureus contributes to its improved potency against clinical strains of S. aureus that are resistant to other quinolones.

Susceptibility of penicillin-resistant and penicillin-susceptible Streptococcus pneumoniae to newer antimicrobial agents

Agar dilution minimum inhibitory concentration (MIC) methodology, according to NCCLS guidelines, was used to test the activity of three glycopeptides (LY 333328 [LY], vancomycin [VAN], and teicoplanin [TEI]), four fluoroquinolones (trovafloxacin [TRO], BAY 12-8039 [BAY], ciprofloxacin [CIP], and ofloxacin [OFL]), five macrolide-lincosamide-streptogramin antibiotics (erythromycin [ERY], azithromycin [AZI], miocamycin [MOM], clindamycin CLN], and quinupristin-dalfopristin [SYN] against 126 Streptococcus pneumoniae strains, isolated in Lozano Blesa Hospital of Zaragoza (Spain). MIC50/MIC90 (microg/ml) values for penicillin-susceptible (PS), penicillin-intermediate (PI) and penicillin-resistant (PR) strains show an excellent antipneumococcal activity of LY 333326--a new glycopeptide, for the fluoroquinolones trovafloxacin and moxifloxacin [BAY 12-8039], and for quinupristin/dalfopristin, regardless of the resistance phenotype of the strains.

In vitro and in vivo antimicrobial activities of T-3811ME, a novel des-F(6)-quinolone

The in vitro and in vivo activities of T-3811ME, a novel des-F(6)-quinolone, were evaluated in comparison with those of some fluoroquinolones, including a newly developed one, trovafloxacin. T-3811, a free base of T-3811ME, showed a wide range of antimicrobial spectra, including activities against Chlamydia trachomatis, Mycoplasma pneumoniae, and Mycobacterium tuberculosis. In particular, T-3811 exhibited potent activity against various gram-positive cocci, with MICs at which 90% of the isolates are inhibited (MIC90s) of 0.025 to 6.25 microgram/ml. T-3811 was the most active agent against methicillin-resistant Staphylococcus aureus and streptococci, including penicillin-resistant Streptococcus pneumoniae (PRSP). T-3811 also showed potent activity against quinolone-resistant gram-positive cocci with GyrA and ParC (GrlA) mutations. The activity of T-3811 against members of the family Enterobacteriaceae and nonfermentative gram-negative rods was comparable to that of trovafloxacin. In common with other fluoroquinolones, T-3811 was highly active against Haemophilus influenzae, Moraxella catarrhalis, and Legionella sp., with MIC90s of 0.0125 to 0.1 microgram/ml. T-3811 showed a potent activity against anaerobic bacteria, such as Bacteroides fragilis and Clostridium difficile. T-3811 was the most active agent against C. trachomatis (MIC, 0.008 microgram/ml) and M. pneumoniae (MIC90, 0.0313 microgram/ml). The activity of T-3811 against M. tuberculosis (MIC90, 0.0625 microgram/ml) was potent and superior to that of trovafloxacin. In experimental systemic infection with a GrlA mutant of S. aureus and experimental pneumonia with PRSP in mice, T-3811ME showed excellent therapeutic efficacy in oral and subcutaneous administrations.

Trovafloxacin in combination with vancomycin against penicillin-resistant pneumococci in the rabbit meningitis model

Trovafloxacin, a new fluoroquinolone, produced bactericidal activity (-0.33 +/- 0.13 delta log10 CFU/ml.h; intravenously [i.v.] administered dose, 15 mg/kg) comparable to that of vancomycin (-0.39 +/- 0.18 delta log10 CFU/ml.h; i.v. admininistered dose, 20 mg/kg) in the treatment of experimental meningitis in rabbits due to a pneumococcal strain highly resistant to penicillin (MIC of penicillin G, 4 micrograms/ml). The combination of both drugs significantly increased (P < 0.05) the killing rate (-0.60 +/- 0.23 delta log10 CFU/ml.h) compared to that produced by either monotherapy. These results were also confirmed in vitro.

Trovafloxacin: a new fluoroquinolone

OBJECTIVE

To review the pharmacology, antimicrobial activity, pharmacokinetics, clinical efficacy, and safety of trovafloxacin.

DATA SOURCES

A MEDLINE search (January 1966-April 1998) was conducted for relevant literature using the terms CP-99,219, CP-116,519, trovafloxacin, and alatrofloxacin. Abstracts published by the American Society of Microbiology during 1995-1997 meetings were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All in vitro, animal, and human studies were reviewed for the antimicrobial activity, pharmacokinetics, efficacy, and safety of trovafloxacin.

DATA SYNTHESIS

Trovafloxacin is a new fluoroquinolone with enhanced activity against gram-positive and anaerobic microorganisms. The oral bioavailability under fasting conditions is approximately 88%. The elimination half-life of trovafloxacin is approximately 10 hours. Less than 10% of trovafloxacin is eliminated unchanged in the urine. Trovafloxacin is effective in the treatment of community-acquired pneumonia and nosocomial pneumonia with cure rates of > 90% and 77%, respectively. Trovafloxacin is comparable with ceftriaxone in the treatment of meningococcal meningitis in children; each produces a cure rate of approximately 90%. In treatment of uncomplicated urinary tract infection, both ciprofloxacin and trovafloxacin achieve an eradication rate of > or = 93%. Trovafloxacin is similar to ofloxacin in the treatment of urogenital Chlamydia trachomatis and acute exacerbations of chronic bronchitis, with clinical success in 97% of patients with each drug. The common adverse effects of trovafloxacin include dizziness, headache, and gastrointestinal intolerance.

CONCLUSIONS

The advantages of once-daily dosing and enhanced activity of trovafloxacin against gram-positive and anaerobic organisms may expand its use over available fluoroquinolones. Further studies are needed to define its role in the treatment of various infectious diseases.

Safety and tolerability of intravenous-to-oral treatment and single-dose intravenous or oral prophylaxis with trovafloxacin

BACKGROUND

The new fourth-generation fluoroquinolone, trovafloxacin, is active in vitro against gram-positive and gram-negative organisms, atypical pathogens, and anaerobes, and has pharmacokinetics permitting once-daily intravenous or oral dosing. Safety/tolerability data from phase II/III clinical trials of sequential intravenous alatrofloxacin to oral trovafloxacin and single-dose intravenous or oral prophylaxis are summarized.

METHODS

All trials were double-blind, randomized, and multicenter. In multidose trials with alatrofloxacin, 1,257 patients requiring initial intravenous therapy received once-daily alatrofloxacin (trovafloxacin prodrug, 200 or 300 mg/day) followed by oral 200 mg/day trovafloxacin. An additional 444 patients received a single alatrofloxacin or trovafloxacin dose prophylactically for surgical procedures.

RESULTS

Therapy with alatrofloxacin was well tolerated. The most common treatment-related adverse events in studies of intravenous alatrofloxacin followed by oral trovafloxacin were nausea, headache, insertion site reaction, and dizziness. In single-dose intravenous or oral prophylaxis studies, insertion-site reaction, pruritus, and insertion-site pain were the most common treatment-related adverse events. No serious quinolone toxicity or drug interactions were reported. The incidence of serious treatment-related adverse events was < 1% in both the alatrofloxacin and comparator groups. In comparative trials, mortality due to all causes after trovafloxacin was similar to that after comparative agents; there was no mortality related to trovafloxacin administration.

CONCLUSION

In this large patient sample, intravenous alatrofloxacin followed by oral trovafloxacin was safe and well tolerated. Serious adverse events, such as phototoxicity, cardiovascular toxicity, and hemolytic anemia associated with older fluoroquinolones, were not noted with trovafloxacin. No interactions of trovafloxacin with other drugs were reported. The safety and tolerability of trovafloxacin, along with in vitro activity against key pathogens and pharmacokinetics permitting once-daily administration, support its oral and intravenous use in patients with obstetric, gynecologic, and intra-abdominal infections as well as for prophylaxis of surgical infection.

Pharmacodynamics and microbiology of trovafloxacin in animal models of surgical infection

Trovafloxacin provides broad in vitro and in vivo coverage of the aerobic and anaerobic pathogens found frequently in surgical infections. In vitro susceptibility testing indicated that trovafloxacin inhibited gram-positive staphylococci and enterococci, numerous gram-negative organisms, including Escherichia coli, and anaerobic pathogens, such as Bacteroides fragilis. Trovafloxacin protected mice from lethal infections induced by gram-negative or gram-positive organisms, even when these organisms were inoculated in combination with B. fragilis. Trovafloxacin protected rats in models of intra-abdominal sepsis induced by inoculation with E. coli and B. fragilis or with multiple aerobic and anaerobic pathogens. In these experimental models, trovafloxacin protected rats from lethal infection, reduced intra-abdominal abscess formation, and inhibited bacterial growth. Drug concentrations were greater in intra-abdominal abscesses than in serum, reflecting the good tissue penetration of trovafloxacin. These results indicate that trovafloxacin may be effective in prophylaxis and treatment of mixed infections in surgical patients.

Overview of quinolones in the treatment and prevention of surgical infection

Postoperative infection remains a complication of surgical procedures, resulting in increased morbidity, mortality, and cost. The frequent polymicrobial etiology and emerging patterns of resistance continue to compromise cure rates. Although quinolones have many attractive properties for the surgical setting, combination therapy is routinely indicated for appropriate coverage. Advanced-generation quinolones, such as trovafloxacin, offer an increased antimicrobial spectrum, including activity against important surgical pathogens, and longer elimination half-lives. These newer agents may be used intravenously or orally as once-daily single-agent therapy for surgical prophylaxis, and in place of combination therapy for complex intra-abdominal and pelvic infections.

The bioavailability of nasogastric versus tablet-form oral trovafloxacin in healthy subjects

BACKGROUND

Patients in the hospital, as well as those in home care settings, often require nutritional supplementation with enteral feeding solutions. In addition, patients with serious infections who are clinically unstable often cannot maintain adequate intake by mouth and may require an alternative to oral antibiotic administration. However, delivery of crushed oral formulations of drugs via nasogastric tubes is often carried out without adequate bioavailability data, and this method of administration may not always be equivalent to oral drug delivery.

METHODS

In an open-label, randomized, four-period, four-treatment, cross-over study, 24 healthy volunteers were given one dose of each of the following treatments, with a 7-day wash-out between dosing periods: Treatment A: two 100-mg trovafloxacin tablets given orally with 240 mL water; Treatment B: two crushed 100-mg trovafloxacin tablets suspended in water and administered through a nasogastric tube into the stomach; Treatment C: two crushed 100-mg trovafloxacin tablets suspended in water and administered through a nasogastric tube into the duodenum; or Treatment D: two crushed 100-mg trovafloxacin tablets suspended in water and given through a nasogastric tube into the stomach concomitantly with an enteral feeding solution (240 mL full-strength Osmolite).

RESULTS

Pharmacokinetic analyses showed that the bioavailability of trovafloxacin after administration of crushed tablets into the stomach with or without concomitant enteral feeding was not significantly different from that of the orally administered whole tablets: the 90% confidence limits of the area under the concentration-time curve (AUC(0-infinity)) for Treatment B versus Treatment A (91.3%, 109.5%) and Treatment D versus Treatment A (91.6%, 109.9%) were well within the bioequivalence criteria of 80% to 125%. Results of analysis of variance (ANOVA) indicated no significant sequence, period, or treatment-by-period interaction effects. Administration of trovafloxacin into the duodenum (Treatment C) resulted in reduced systemic exposure to trovafloxacin, with a 31% decrease in AUC(0-infinity) and a 30% decrease in peak serum concentration (Cmax) compared to oral administration. Time to peak serum concentration (Tmax) was 1.7 hours after oral administration of trovafloxacin and 1.1 hours after administration directly into the stomach or duodenum through a nasogastric tube in the absence of concomitant enteral feeding. All four treatments were well tolerated; no participant discontinued the study due to adverse events and no serious adverse events were reported.

CONCLUSIONS

These results showed that administration of crushed trovafloxacin tablets through a nasogastric tube into the stomach, with or without concomitant enteral feeding, achieves absorption and tolerability comparable to those of orally administered trovafloxacin tablets.

Treatment of acute gynecologic infections with trovafloxacin. Trovafloxacin Surgical Group

BACKGROUND

Trovafloxacin, a broad-spectrum fourth-generation quinolone with gram-positive and gram-negative aerobic and anaerobic bacterial activity, is available in oral and intravenous formulations. The objective of this prospective, multicenter, double-blind, randomized study was to compare the efficacy of trovafloxacin with that of cefoxitin, an approved drug for treatment of acute gynecologic infections, together with amoxicillin/clavulanic acid as oral follow-on treatment.

METHODS

Patients with a clinical diagnosis of acute pelvic infection received either intravenous alatrofloxacin with oral trovafloxacin follow-on (trovafloxacin) or a combined regimen of cefoxitin followed by amoxicillin/clavulanic acid for a maximum of 14 days. The primary endpoint was clinical response to therapy on follow-up at day 30.

RESULTS

Clinical success rates were comparable between the trovafloxacin (n = 107) and comparative (n = 119) groups at study end (90% vs. 86%, respectively; 95% confidence interval, -4.5, 12.5). Among clinically evaluable patients, clinical success rates for infections involving Enterococcus species were higher with trovafloxacin than with the comparative regimen at the end of treatment (96% and 85%) and at study end (96% and 86%).

CONCLUSION

Intravenous alatrofloxacin followed by oral trovafloxacin for a maximum of 14 days of total therapy was efficacious in the treatment of acute pelvic infections.

Trovafloxacin in the treatment of intra-abdominal infections: results of a double-blind, multicenter comparison with imipenem/cilastatin. Trovafloxacin Surgical Group

BACKGROUND

Trovafloxacin, a new broad-spectrum fourth-generation quinolone, has in vitro activity against most gram-negative and gram-positive anaerobes and aerobes. Trovafloxacin is available as both an intravenous formulation, alatrofloxacin, and a single daily oral tablet. Excellent tissue pharmacokinetics and oral bioavailability suggest usefulness in the treatment of complicated intra-abdominal infections. Thus, the efficacy of alatrofloxacin followed by oral trovafloxacin was compared with the standard regimen of intravenous imipenem/cilastatin followed by oral amoxicillin/clavulanic acid in this prospective, multicenter, double-blind trial.

METHODS

Patients were randomized to receive either 300 mg alatrofloxacin daily followed by 200 mg oral trovafloxacin daily or 1 g imipenem/cilastatin intravenously thrice daily followed by 500 mg oral amoxicillin/clavulanic acid thrice daily for up to 14 days following surgical intervention of a documented intra-abdominal infection. Efficacy was assessed at the end of therapy and at follow-up (day 30).

RESULTS

At the end of the study, cure or improvement occurred in 83% (129/156) and 84% (127/152) of clinically evaluable patients in the trovafloxacin and comparative groups, respectively. Pathogen eradication rates, adverse-event profiles, and significant laboratory abnormalities were comparable between groups.

CONCLUSION

Intravenous alatrofloxacin with or without oral trovafloxacin was as effective as intravenous imipenem/cilastatin followed by oral amoxicillin/clavulanic acid in complicated intra-abdominal infections.

Comparative in-vitro activities of trovafloxacin, ciproflaxacin, ofloxacin, and broad-spectrum beta-lactams against aerobe blood culture isolates

The in vitro activity of trovafloxacin, a new fluoroquinolone, was compared with that of ciprofloxacin, ofloxacin, fleroxacin, ceftazidime, piperacillin/tazobactam, and meropenem against 613 consecutively recovered blood isolates from recently hospitalized patients. Susceptibility testing was performed by agar dilution according to NCCLS guidelines. Test strains included Acinetobacter species (n = 26), Escherichia coli (n = 137), Enterobacter species (n = 27), Klebsiella species (n = 42), Proteus species (n = 16), Pseudomonas aeruginosa (n = 28), Serratia marcescens (n = 13), Stenotrophomonas maltophilia (n = 7), enterococci (n = 54), coagulase-negative staphylococci (n = 38), Staphylococcus aureus (n = 137), Streptococcus pneumoniae (n = 27), beta-haemolytic streptococci (n = 13), and viridans group streptococci (n = 48). The overall respective MICs at which 50% and 90% of isolates were inhibited (MIC50s and MIC90s) were as follows: trovafloxacin, 0.06 and 1 mg/l; ciprofloxacin, 0.25 and 4 mg/l; ofloxacin, 0.5 and 4 mg/l; fleroxacin, 0.5 and 16 mg/l; ceftazidime, 2 and 128 mg/l; piperacillin/tazobactam, 2 and 8 mg/l; meropenem, 0.06 and 4 mg/l. For the quinolones, the rank order of activity against gram-negative microorganisms was ciprofloxacin > trovafloxacin > ofloxacin = fleroxacin, against gram-positive organisms, trovafloxacin > ciprofloxacin = ofloxacin > fleroxacin. Data obtained showed the similar activity of trovafloxacin and ciprofloxacin against gram-negative pathogens and the superior activity of trovafloxacin against gram-positive bacteria thus making it a potential candidate for the empiric treatment of patients with suspected bacteremia and sepsis.

The prevalence of fluoroquinolone resistance among clinically significant respiratory tract isolates of Streptococcus pneumoniae in the United States and Canada--1997 results from the SENTRY Antimicrobial Surveillance Program

As part of the SENTRY antimicrobial resistance surveillance program, a total of 1100 clinically significant respiratory tract isolates of Streptococcus pneumoniae were tested for susceptibility to six fluoroquinolone antimicrobial agents: ciprofloxacin, levofloxacin, gatifloxacin, grepafloxacin, sparfloxacin, and trovafloxacin. Isolates were obtained during the 5-month period, February to June, 1997 from 27 United States medical center laboratories and seven laboratories in Canadian health care institutions. All testing was performed in a single center. Of 1100 test strains, 3 (0.3%), all from different U.S. centers, were fluoroquinolone resistant. Among the remaining 1097 fluoroquinolone-susceptible isolates, the rank order of activity among the six agents tested in this study was grepafloxacin (modal MIC = 0.25 microgram/mL) = trovafloxacin (modal MIC = 0.25 microgram/mL) = sparfloxacin (0.25 microgram/mL) > gatifloxacin (0.5 microgram/mL) > levofloxacin (1 microgram/mL) = ciprofloxacin (1 microgram/mL). Fluoroquinolone resistance is currently uncommon among respiratory tract isolates of S. pneumoniae in North America, but there exist clear differences between the in vitro activities of different fluoroquinolones for this organism.

Concentrations of trovafloxacin in colonic tissue and peritoneal fluid after intravenous infusion of the prodrug alatrofloxacin in patients undergoing colorectal surgery

BACKGROUND

Trovafloxacin is a new fourth-generation fluoroquinolone whose pharmacokinetics and in vitro activity suggest that it is well suited for antibiotic prophylaxis in elective colorectal surgery. Alatrofloxacin is a prodrug that is rapidly hydrolyzed to trovafloxacin in the body.

METHODS

Twelve patients received a single dose of alatrofloxacin equivalent to 200 mg trovafloxacin by intravenous infusion over 1 hour. Surgery was started at various time points relative to infusion time to allow determination of trovafloxacin concentrations in serum, colonic tissue, and peritoneal fluid as a function of time.

RESULTS

The concentration in the earliest colonic tissue sample (1.4 hours after dosing) was 1.4 microg/g. The maximum colonic tissue concentration was 2.8 microg/g in a sample taken 2 hours after dosing. Colonic tissue/serum concentration ratios in samples taken 2-10 hours after the end of infusion ranged from 0.8 to 1.47. Concentrations of trovafloxacin in peritoneal fluid ranged from below the level of quantitation to 2.1 microg/mL at the time of colonic tissue sampling and from below the level of quantitation to 2.5 microg/mL at the time of wound closure. Alatrofloxacin was well tolerated.

CONCLUSIONS

After a single intravenous dose of alatrofloxacin equivalent to 200 mg trovafloxacin, trovafloxacin is distributed rapidly into colonic tissue and peritoneal fluids. Tissue concentrations approximate serum concentrations and decline in parallel for up to 10 hours after dosing.

Oral trovafloxacin compared with intravenous cefoxitin in the prevention of bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease. Trovafloxacin Surgical Group

BACKGROUND

Trovafloxacin is a new fourth-generation fluoroquinolone whose pharmacokinetics and in vitro activity suggest that it is well suited for antibiotic prophylaxis in elective hysterectomy.

METHODS

In a randomized, double-blind, multicenter study, parallel groups of women 18 years of age or older received either 200 mg trovafloxacin by mouth and intravenous (i.v.) placebo or 2 g cefoxitin by i.v. infusion and placebo by mouth before elective vaginal or abdominal hysterectomy for nonmalignant disease.

RESULTS

In the 103 and 97 patients in the trovafloxacin and cefoxitin groups, respectively, who were evaluable for efficacy, the prophylactic success rates at hospital discharge (96% in both groups) and 30 +/- 6 days after hysterectomy (88% and 91% in the trovafloxacin and cefoxitin groups, respectively) were statistically equivalent. Both antibiotics were well tolerated.

CONCLUSION

A single oral 200 mg dose of trovafloxacin is as effective and safe as a standard cefoxitin parenteral regimen in the prevention of primary bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease.

In vitro activity of quinupristin/dalfopristin and newer quinolones combined with gentamicin against resistant isolates of Enterococcus faecalis and Enterococcus faecium

In a study designed to obtain data on compounds active against enterococci, the minimum inhibitory concentrations (MICs) of quinupristin/dalfopristin (RP 59500) and the novel quinolones DU-6859a, trovafloxacin, levofloxacin, and sparfloxacin were determined for 122 Enterococcus faecalis and seven Enterococcus faecium isolates. In addition, 15 Enterococcus faecalis isolates resistant to gentamicin, DU-6859a, and trovafloxacin were exposed over time to combinations of DU-6859a plus gentamicin and trovafloxacin plus gentamicin. DU-6859a and trovafloxacin were found to be the most active compounds against Enterococcus faecalis and DU-6859a and RP 59500 against Enterococcus faecium. Synergy between either DU-6859a or trovafloxacin and gentamicin was observed with 27 to 35% of the isolates. It is concluded that DU-6859a and trovafloxacin are very potent against enterococci, especially when combined with gentamicin.

Pharmacokinetics of [18F]trovafloxacin in healthy human subjects studied with positron emission tomography

Tissue pharmacokinetics of trovafloxacin, a new broad-spectrum fluoroquinolone antimicrobial agent, were measured by positron emission tomography (PET) with [18F]trovafloxacin in 16 healthy volunteers (12 men and 4 women). Each subject received a single oral dose of trovafloxacin (200 mg) daily beginning 5 to 8 days before the PET measurements. Approximately 2 h after the final oral dose, the subject was positioned in the gantry of the PET camera, and 1 h later 10 to 20 mCi of [18F]trovafloxacin was infused intravenously over 1 to 2 min. Serial PET images and blood samples were collected for 6 to 8 h, starting at the initiation of the infusion. Drug concentrations were expressed as the percentage of injected dose per gram, and absolute concentrations were estimated by assuming complete absorption of the final oral dose. In most tissues, there was rapid accumulation of the radiolabeled drug, with high levels achieved within 10 min after tracer infusion. Peak concentrations of more than five times the MIC at which 90% of the isolates are inhibited (MIC90) for most members of Enterobacteriaceae and anaerobes (>10-fold for most organisms) were achieved in virtually all tissues, and the concentrations remained above this level for more than 6 to 8 h. Particularly high peak concentrations (micrograms per gram; mean +/- standard error of the mean [SEM]) were achieved in the liver (35.06 +/- 5.89), pancreas (32.36 +/- 20. 18), kidney (27.20 +/- 10.68), lung (22.51 +/- 7.11), and spleen (21. 77 +/- 11.33). Plateau concentrations (measured at 2 to 8 h; micrograms per gram; mean +/- SEM) were 3.25 +/- 0.43 in the myocardium, 7.23 +/- 0.95 in the lung, 11.29 +/- 0.75 in the liver, 9.50 +/- 2.72 in the pancreas, 4.74 +/- 0.54 in the spleen, 1.32 +/- 0.09 in the bowel, 4.42 +/- 0.32 in the kidney, 1.51 +/- 0.15 in the bone, 2.46 +/- 0.17 in the muscle, 4.94 +/- 1.17 in the prostate, and 3.27 +/- 0.49 in the uterus. In the brain, the concentrations (peak, approximately 2.63 +/- 1.49 microg/g; plateau, approximately 0.91 +/- 0.15 microg/g) exceeded the MIC90s for such common causes of central nervous system infections as Streptococcus pneumoniae (MIC90, <0.2 microg/ml), Neisseria meningitidis (MIC90, <0.008 microg/ml), and Haemophilus influenzae (MIC90, <0.03 microg/ml). These PET results suggest that trovafloxacin will be useful in the treatment of a broad range of infections at diverse anatomic sites.

Efficacy of trovafloxacin, a new quinolone antibiotic, in experimental staphylococcal endocarditis due to oxacillin-resistant strains

Therapeutic options for severe infections caused by strains of oxacillin-resistant Staphylococcus aureus (ORSA) and coagulase-negative staphylococci (ORSE) are very limited. With the increasing resistance of such strains to aminoglycosides, rifampin, and currently available quinolone agents, as well as the recent documentation of increasing resistance of ORSA to vancomycin (VANCO), new treatment alternatives are imperative. The in vivo efficacy of trovafloxacin (TROVA), a new quinolone agent with excellent antistaphylococcal activity in vitro, against experimental endocarditis (IE) due to beta-lactamase-producing ORSA and ORSE strains (ORSA and ORSE IE) was evaluated. TROVA (25 mg/kg of body weight intravenously [i.v.] twice daily [b.i.d]) was compared to VANCO (20 mg/kg i.v. b.i.d.) and two regimens of ampicillin-sulbactam (AMP-SUL; 200 mg/kg intramuscularly [i.m.] three times a day [t.i.d.] and 20 mg/kg i.m. b.i.d.), with all agents given for 3 or 6 days. AMP-SUL was included as a comparative treatment regimen because of its proven efficacy against experimental ORSA and ORSE IE. For both ORSA and ORSE IE, TROVA, AMP-SUL, and VANCO each reduced staphylococcal densities in vegetations compared to untreated controls (P < 0.01). For ORSA IE, TROVA was the most rapidly bactericidal agent--although not to a statistically significant degree--correlating with its superior bactericidal effect in vitro compared to those of VANCO and AMP-SUL.

A comparative study on the efficacy of the new quinolone alatrofloxacin in the treatment of experimental legionellosis in guinea pigs

The in vivo efficacy of trovafloxacin, intraperitoneally administered as alatrofloxacin (CP-116,517), was assessed and compared with that of erythromycin, alone or in combination with rifampicin, in a model of Legionella pneumophila pneumonia in guinea pigs. Trovafloxacin (5 mg/kg administered as alatrofloxacin once daily for 7 days) gave a survival rate of 100% in infected animals. Clearance of bacteria and of bacteria-induced lesions from lungs was achieved by day 6 post-inoculation. The lungs of trovafloxacin-treated animals remained free of bacteria at day 28 post-challenge. Trovafloxacin proved as effective as erythromycin administered intraperitoneally, but was superior to erythromycin alone. or in combination with rifampicin, when given orally.

Trovafloxacin versus high-dose amoxicillin (1 g three times daily) in the treatment of community-acquired bacterial pneumonia

Once-daily trovafloxacin 200 mg was compared with high-dose amoxicillin, 1 g three times daily, given for 7 to 10 days. At end of treatment (day 10), the response was clinically successful (cure + improvement) in 93% of 152 clinically evaluable trovafloxacin patients and in 89% of 160 amoxicillin patients. At study end (day 35), respective rates were 91% and 81% (95% confidence interval: 1.6, 17.6; P=0.01). In evaluable patients with positive baseline radiographs, 93% of trovafloxacin and 88% of amoxicillin patients demonstrated radiological resolution at end of treatment. Streptococcus pneumoniae and Haemophilus influenzae eradication rates were comparable at end of treatment in both treatment groups, but at study end Streptococcus pneumoniae eradication rates were higher in trovafloxacin patients (100% vs 81%). At study end, all four trovafloxacin patients with baseline penicillin-resistant Streptococcus pneumoniae were clinically cured with pathogen eradication, whereas two of five amoxicillin patients with baseline penicillin-resistant Streptococcus pneumoniae were clinical failures with pathogen persistence. For patients in whom no pathogen was identified, trovafloxacin was significantly more effective at end of treatment (P=0.096) and study end (P=0.013). Treatment-related adverse events were comparable; the most common were headache, vomiting and dizziness in trovafloxacin patients, and diarrhoea. headache and abdominal pain in amoxicillin patients.

Bacteriological activity of trovafloxacin, a new quinolone, against respiratory tract pathogens

The use of established fluoroquinolones, such as ciprofloxacin and ofloxacin, as empirical therapy for the treatment of moderate-to-severe respiratory tract infections is limited by their poor activity against gram-positive and atypical pathogens. Data from in vitro susceptibility studies and in vivo animal protection models suggest that the new fluoroquinolone, trovafloxacin, compared with ciprofloxacin and ofloxacin offers equivalent activity against gram-negative pathogens and improved activity against gram-positive pathogens. In particular, susceptibility data indicate that trovafloxacin is at least 16-fold more potent than either ciprofloxacin or ofloxacin against penicillin-susceptible and penicillin-resistant strains of Streptococcus pneumoniae. Other susceptible pathogens include Streptococcus pyogenes, vancomycin-susceptible Enterococcus faecalis and the atypical respiratory pathogens Legionella pneumophila, Mycoplasma pneumoniae and Chlamydia pneumoniae. In vivo studies involving models of protection against acute systemic infection and pneumococcal pneumonia in mice, and Legionnaires' disease in guinea pigs, indicate that the antibacterial spectrum observed for trovafloxacin in vitro extends to the in vivo setting. Together, these findings suggest that trovafloxacin may offer clinical efficacy against respiratory pathogens superior to that of ciprofloxacin and of ofloxacin, and may find a useful role as empiric therapy in both the community and hospital setting.

Postantibiotic effect of trovafloxacin against gram-positive and -negative organisms

Trovafloxacin pneumococcal and staphylococcal postantibiotic effects (PAEs) were 0.7 to 1.8 and 0.7 to 2.4 h, respectively. For Escherichia coli and Pseudomonas aeruginosa, PAEs were 2.4 to 4.4 h. Pneumococcal and staphylococcal postantibiotic sub-MIC effects (PA-SMEs) (0.4 times the MIC) were 2.3 to 3.7 and 2.4 to > 9.2 h, respectively, and E. coli PA-SMEs (0.3 times the MIC) were 6.8 to > 12.0 h. For one P. aeruginosa strain, the PA-SME (0.4 times the MIC) was > 10 h; in the other, rapid bactericidal activity precluded measurement.

Comparison of in vitro activity of trovafloxacin against gram-positive and gram-negative organisms with quinolones and beta-lactam antimicrobial agents

The in vitro activity of trovafloxacin against 721 Gram-negative and 498 Gram-positive organisms was determined by the standard microdilution broth method using commercially prepared frozen microtiter plates. The activity of trovafloxacin was compared to ofloxacin, ciprofloxacin, amoxicillin/clavulanate, ampicillin/sulbactam (1:1), piperacillin/tazobactam, ceftriaxone, and imipenem. Trovafloxacin had equal or greater activity compared with the other agents tested against Citrobacter diversus, Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Stenotrophomonas maltophilia, Serratia marcescens, staphylococci, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus viridans, group G streptococci, Enterococcus faecalis, and E. faecium. The reliability of the commercially prepared plates for testing the in vitro activity of the quinolones was evaluated by comparing identical isolates also tested by broth microdilution using laboratory prepared plates. The commercially prepared plates generally correlated, within one- to twofold dilutions, with the laboratory prepared plates. There was, however, a large discrepancy obtained when testing Enterobacter agglomerans and E. cloacae, where the commercially prepared plates yielded a significantly higher MIC90 value.

Efficacy of trovafloxacin against penicillin-susceptible and multiresistant strains of Streptococcus pneumoniae in a mouse pneumonia model

The increasing emergence of penicillin-resistant and multidrug-resistant strains of Streptococcus pneumoniae will create a serious therapeutic problem in coming years. Trovafloxacin is a novel naphthyridone quinolone with promising activity against S. pneumoniae, including penicillin-resistant strains (MIC for 90% of the isolates tested, 0.25 microg/ml). We compared its in vivo efficacy with that of other fluoroquinolones (ciprofloxacin, temafloxacin, and sparfloxacin) and a reference beta-lactam (amoxicillin) in a model of acute experimental pneumonia. Immunocompetent Swiss mice were infected by peroral tracheal delivery of a virulent, penicillin-susceptible strain (MIC, 0.03 microg/ml); leukopenic Swiss mice were infected with three poorly virulent, penicillin-resistant strains (MICs, 4 to 8 microg/ml) and a ciprofloxacin-resistant strain (MIC, 32 microg/ml). Treatments were started 6 h (immunocompetent mice) or 3 h (leukopenic mice) after infection. Doses ranging from 12.5 to 300 mg/kg were given at 12- or 8-h intervals for 3 days. Trovafloxacin (25 mg/kg) was the most effective agent in vivo against penicillin-susceptible and -resistant strains. Corresponding survival rates were 2- to 4-fold higher than with 50-mg/kg sparfloxacin or temafloxacin and 8- to 16-fold higher than with 100-mg/kg ciprofloxacin. The ratios of the area under the concentration-time curve to the MIC in serum and lung tissue were more favorable with trovafloxacin than with the other quinolones. Efficacy in vivo correlated with pharmacokinetic parameters. Trovafloxacin shows potential for the treatment of infections due to penicillin-susceptible and -resistant S. pneumoniae but appears to be ineffective against a ciprofloxacin-resistant strain.

Efficacy of trovafloxacin against experimental Staphylococcus aureus endocarditis

Trovafloxacin is a new fluoronaphthyridone chemically and functionally related to members of the fluoroquinolone class of antimicrobial agents. The in vivo efficacy of the drug was compared with that of vancomycin by using the rabbit model of left-sided endocarditis. Rabbits infected with either a nafcillin-susceptible or -resistant test strain were treated with trovafloxacin (13.3 mg/kg of body weight every 12 h) or vancomycin (25 mg/kg of body weight every 8 h) for 4 days. In comparison with untreated controls, both antimicrobial agents effectively cleared bacteremia and significantly reduced bacterial counts in vegetations and tissues of animals infected with either test strain. No resistance to trovafloxacin emerged in test strains during therapy. We conclude that in this model trovafloxacin is as efficacious as vancomycin is and may serve as a viable alternative to vancomycin for use in humans with similar infections.

Quality control limits for dilution and disk diffusion susceptibility tests of trovafloxacin against eight quality control strains

A 10-laboratory collaborative effort was designed to generate data to propose quality control limits for susceptibility tests of trovafloxacin. Broth microdilution, agar dilution, and disk diffusion tests were evaluated with eight different control strains. All tests were reproducible, and control limits are proposed.

Synergistic activity of trovafloxacin with other agents against gram-positive and -negative organisms

The synergistic activity of trovafloxacin with other agents against 55 Gram-positive and -negative bacteria was determined by checkerboard titration. Synergistic fractional inhibitory concentration (FIC) indices (< or = 0.5) were seen in two methicillin-susceptible and one methicillin-resistant Staphyloccocus aureus with teicoplanin, one of each of the latter two with vancomycin; one methicillin-resistant coagulase-negative Staphylococcus with rifampin and one with fusidic acid; five Stenotrophomonas maltophilia with cefoperazone; three Pseudomonas aeruginosa with ticarcillin/clavulanate, four with aztreonam, two with ceftazidime, one with tobramycin, one with cefoperazone, and one with ceftriaxone; one pneumococcus with ceftriaxone; one Enterococcus faecalis with ceftriaxone, and one with vancomycin; two Bacteroides fragilis with metronidazole, two with clindamycin, and one with cefoxitin; and one Clostridium perfringens with metronidazole and one with clindamycin. All other FIC indices were additive/indifferent (0.51-2.0), and no antagonistic FIC indices (> 4.0) were observed.

Randomized trial of trovafloxacin and ofloxacin for single-dose therapy of gonorrhea. Trovafloxacin Gonorrhea Study Group

PURPOSE

To compare trovafloxacin, a new quinolone antibiotic with enhanced activity against Neisseria gonorrhoeae, with ofloxacin as single-dose oral therapy for uncomplicated gonococcal urethritis or cervicitis.

PATIENTS AND METHODS

In this multicenter, double-blind trial, 625 patients (270 men, 355 women) with uncomplicated gonococcal urethritis or cervicitis received one 100-mg tablet of trovafloxacin or two 200-mg capsules of ofloxacin as a single dose under direct supervision.

RESULTS

Single-dose oral therapy with trovafloxacin was equivalent both bacteriologically and clinically to ofloxacin. Among evaluable patients, N gonorrhoeae was eradicated in 99% of trovafloxacin recipients and in 98% of ofloxacin recipients. Each treatment was well tolerated; vaginitis was the most frequently observed side effect (4% trovafloxacin, 7% ofloxacin).

CONCLUSION

Based on the results presented here, trovafloxacin is a promising agent for single-dose therapy of uncomplicated gonorrhea.

Treatment of enterococcal pyelonephritis with trovafloxacin and rifampin: in vitro-in vivo contrast

The in vitro bactericidal interaction of trovafloxacin and rifampin against Enterococcus spp. has indicated that antagonism occurs between these two antimicrobial agents. This drug combination was examined in vivo in rats with experimental pyelonephritis. The rats received trovafloxacin, rifampin, or both drugs. On the basis of the mean log10 CFU of Enterococcus faecalis from the kidneys, there was no evidence that trovafloxacin and rifampin were antagonistic in vivo.

Mechanisms of fluoroquinolone resistance in genetically related strains of Staphylococcus aureus

Fluoroquinolone resistance in Staphylococcus aureus results from amino acid substitutions at particular locations in the DNA gyrase A and B subunits as well as in the topoisomerase IV A subunit and from NorA-mediated efflux. More than one resistance mechanism may be present in a single strain. Fluoroquinolone-resistant derivatives of SA-1199, a methicillin-susceptible S. aureus strain, were selected in vivo or in vitro, and their mechanisms of fluoroquinolone resistance were identified. We found that many of the resistance mechanisms described above can develop in derivatives of a single parent strain, either singly or in combination, and can arise in a single step. Variances in MICs for strains with the same apparent resistance mechanisms likely are due to the presence of new or undetected but established means of fluoroquinolone resistance. NorA-mediated resistance can occur in the apparent absence of topoisomerase mutations and in some strains may be the result of a promoter region mutation causing increased expression of norA. However, increased expression of norA can occur independently of this mutation, suggesting that a regulatory locus for this gene exists elsewhere on the chromosome.

In vitro activity of the combination of trovafloxacin and other antibiotics against enterococci

The activities of trovafloxacin and ciprofloxacin against 38 strains of non-beta-lactamase-producing enterococci, resistant to ampicillin, 34 strains susceptible to ampicillin, and 3 vancomycin-resistant enterococci were studied. Trovafloxacin was more active than ciprofloxacin against all the enterococci studied. The ampicillin-resistant strains were more susceptible than the ampicillin-susceptible strains to both agents. The effect of combining trovafloxacin with gentamicin, ampicillin-sulbactam, novobiocin, rifampin, teicoplanin, and vancomycin was determined for 17 strains by the checkerboard method. An additive effect by inhibition was seen with all antibiotics studied. The results by killing varied with the different agents studied. Gentamicin, ampicillin-sulbactam, and novobiocin produced an additive killing effect with trovafloxacin. Reduced killing was seen when rifampin, vancomycin, or teicoplanin were added to trovafloxacin.

In vitro extracellular and intracellular activity of two newer and two earlier fluoroquinolones against Listeria monocytogenes

Two new fluoroquinolones (trovafloxacin and sparfloxacin) with enhanced activity against gram-positive pathogens and two earlier compounds (ciprofloxacin and ofloxacin) were tested for their in vitro inhibitory and bactericidal activity against 80 strains of Listeria monocytogenes. All strains were uniformly highly susceptible to trovafloxacin, the MIC90 being 0.25 mg/l. Resistance to sparfloxacin was not detected, however the MIC90 of sparfloxacin was eight times that of trovafloxacin. A few strains were resistant to ciprofloxacin and ofloxacin (MIC90 4 mg/l for both drugs). MBCs usually exceeded MICs by 2 to 4 times. The MBC90 of trovafloxacin (1 mg/l) was lower than that of the other three drugs (8 mg/l). After checking their ability to enter and grow within human enterocyte-like Caco-2 cells, four strains were used to study the intracellular activity and eradicating power of the four quinolones. Trovafloxacin was more active than sparfloxacin and the earlier fluoroquinolones in terms of both intracellular killing and inhibition of a cytopathogenic effect. The uniform high-level activity of trovafloxacin against Listeria monocytogenes isolates in conventional in vitro assays and its extracellular and intracellular killing of invasive strains suggest that this and maybe other new fluoroquinolones should be further investigated as possible anti-listerial agents.

Comparative in vitro activities of trovafloxacin (CP-99,219) against 221 aerobic and 217 anaerobic bacteria isolated from patients with intra-abdominal infections

Four hundred thirty-eight bacteria cultured from specimens of patients with serious intra-abdominal infections were tested by agar dilution against trovafloxacin and other quinolones and antimicrobial agents. Trovafloxacin inhibited 435 strains (99.3%) at < or =2 microg/ml. All the quinolones had similar activities against Enterobacteriaceae and Pseudomonas sp., but trovafloxacin showed superior activities against streptococci, enterococci, and anaerobic organisms. Because of its excellent in vitro activities against diverse bacteria, trovafloxacin has potential use as a single agent for polymicrobial infections.

Trovafloxacin

Trovafloxacin is a fluoroquinolone antibacterial agent with a broad spectrum of activity. Trovafloxacin has similar or 2-fold lower activity than ciprofloxacin against Enterobacteriaceae and Pseudomonas aeruginosa. Against Haemophilus influenzae and Moraxella catarrhalis, trovafloxacin has similar activity to ciprofloxacin. Other susceptible Gram-negative pathogens include Neisseria gonorrhoeae, Chlamydia trachomatis and mycoplasmas. The drug is active against Gram-positive bacteria and consistently displayed greater activity (2- to 8-fold) than ciprofloxacin against all staphylococci and streptococci tested; activity included methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae. Trovafloxacin has some activity against vancomycin-resistant enterococci. Anaerobes such as Bacteroides and Clostridium spp. are also susceptible to trovafloxacin. Preliminary clinical data suggest that trovafloxacin is effective in the treatment of patients with upper and lower respiratory tract and uncomplicated urinary tract infections and infections caused by C. trachomatis or N. gonorrhoeae. The most frequently noted adverse event with trovafloxacin is dizziness which is reported in 11% of patients versus 3% of those receiving comparator agents. Other commonly reported events (> 1% of patients) are nausea, headache, vomiting, vaginitis and diarrhoea.