Synthesis of Mn-ofloxacin complex, experimental and in silico DNA binding evaluation, biological activity assessment.

Metal-fluoroquinolones have more antibacterial and cytotoxic effects compared to free fluoroquinolones. In this work, a bidentated Mn (II) complex with ofloxacin (MOC) was synthesized and its cytotoxicity activity, oxidative stress and DNA binding were studied. Anti- proliferative and cytotoxic tests revealed that MOC exhibits better anti proliferative and cytotoxic activities compared to OFL which was attributed to the more interaction of MOC with DNA. Therefore, the interaction of MOC with DNA was investigated by using voltammetry, UV-Vis, fluorescence, and in silico methods. The results revealed that MOC interacts with DNA via electrostatic and outside hydrogen binding via minor groove. The proposed DNA binding modes may support the greater in-vitro cytotoxicity of MOC compared to OFL alone.

Antituberculosis, antioxidant and cytotoxicity profiles of quercetin: a systematic and cost-effective in silico and in vitro approach.

The ineffectiveness and the slowdown of newer anti-TB drug approval rates directly indicate searching for potential alternative agents. However, validation of isolated phytochemicals through hit-and-trial experiments is more expensive and time-consuming. Simultaneously, cost-effective computational tools can recognize most potential candidates at an initial stage. The present study selected seven plant-derived polyphenols, then verified anti-TB and drug-ability profiles using advanced computational tools before the experimental study. Among all, the quercetin showed a potential docking-score within -8 to -11 kcal/mol than the standard isoniazid and ofloxacin, -5 to -10 kcal/mol. Additionally, quercetin exhibited a higher drug-ability score of 0.53 than isoniazid 0.19. Further, quercetin exhibited the minimum inhibitory concentration at 6 and 8 µg/mL, while ofloxacin showed at 2 µg/mL against InhA, and katG mutated Mtb-strains, respectively. Parallelly, quercetin showed promising free-radical-scavenging activity from nitric-oxide assay at IC50 = 14.92 µg/mL, and lesser-cytotoxicity from cultured HepG2 cell lines at IC50 = 159 µg/mL, respectively.

In Vivo Bioluminescent Monitoring of Therapeutic Efficacy and Pharmacodynamic Target Assessment of Antofloxacin against Escherichia coli in a Neutropenic Murine Thigh Infection Model.

Antimicrobial resistance among uropathogens has increased the rates of infection-related morbidity and mortality. Antofloxacin is a novel fluoroquinolone with broad-spectrum antibacterial activity against urinary Gram-negative bacilli, such as Escherichia coli This study monitored the in vivo efficacy of antofloxacin using bioluminescent imaging and determined pharmacokinetic (PK)/pharmacodynamic (PD) targets against E. coli isolates in a neutropenic murine thigh infection model. The PK properties were determined after subcutaneous administration of antofloxacin at 2.5, 10, 40, and 160 mg/kg of body weight. Following thigh infection, the mice were treated with 2-fold-increasing doses of antofloxacin from 2.5 to 80 mg/kg administered every 12 h. Efficacy was assessed by quantitative determination of the bacterial burdens in thigh homogenates and was compared with the bioluminescent density. Antofloxacin demonstrated both static and killing endpoints in relation to the initial burden against all study strains. The PK/PD index area under the concentration-time curve (AUC)/MIC correlated well with efficacy (R2 = 0.92), and the dose-response relationship was relatively steep, as observed with escalating doses of antofloxacin. The mean free drug AUC/MIC targets necessary to produce net bacterial stasis and 1-log10 and 2-log10 kill for each isolate were 38.7, 66.1, and 147.0 h, respectively. In vivo bioluminescent imaging showed a rapid decrease in the bioluminescent density at free drug AUC/MIC exposures that exceeded the stasis targets. The integration of these PD targets combined with the results of PK studies with humans will be useful in setting optimal dosing regimens for the treatment of urinary tract infections due to E. coli.

Detection of ofloxacin resistance by nitrate reductase assay in Mycobacterium tuberculosis isolates from extrapulmonary tuberculosis.

CONTEXT: Increased use of fluoroquinolones to treat community-acquired infections has led to the decreased susceptibility to Mycobacterium tuberculosis. There is a paucity of data on ofloxacin (OFX) resistance detection by nitrate reductase assay (NRA). Hence, the present study was carried out to find the efficacy of NRA for detection of OFX resistance in M. tuberculosis isolated from extrapulmonary tuberculosis (EPTB) cases. AIMS: (1) To compare sensitivity, specificity and median time required to obtain results by NRA with economic variant proportion method (PM) for detection of OFX resistance.(2) To determine the extent of OFX resistance in clinical isolates of M. tuberculosis. SETTINGS AND DESIGN: Seventy-three M. tuberculosis isolates from cases of EPTB were subjected to economic variant of PM for isoniazid, rifampicin and OFX. NRA was done for detection of OFX resistance. SUBJECTS AND METHODS: Seventy-three isolates from clinical samples of suspected EPTB received in the Department of Microbiology were included in the study. Drug susceptibility test was performed on Lowenstein-Jensen medium with and without drugs. STATISTICAL ANALYSIS USED: Of turnaround time was done by Mann-Whitney test on SPSS (version 19, released in 2010, IBM Corp, Armonk NY),P < 0.05. RESULTS: OFX resistance was seen in nine isolates. The sensitivity and specificity of OFX resistance by NRA was 100% and 96.87%, respectively. Median time required to obtain results by NRA was 10 days as compared to 28 days by PM. CONCLUSIONS: NRA is a specific and sensitive method for detection of OFX resistance in resource-restricted settings.

Use of Optical Imaging Technology in the Validation of a New, Rapid, Cost-Effective Drug Screen as Part of a Tiered In Vivo Screening Paradigm for Development of Drugs To Treat Cutaneous Leishmaniasis.

In any drug discovery and development effort, a reduction in the time of the lead optimization cycle is critical to decrease the time to license and reduce costs. In addition, ethical guidelines call for the more ethical use of animals to minimize the number of animals used and decrease their suffering. Therefore, any effort to develop drugs to treat cutaneous leishmaniasis requires multiple tiers of in vivo testing that start with higher-throughput efficacy assessments and progress to lower-throughput models with the most clinical relevance. Here, we describe the validation of a high-throughput, first-tier, noninvasive model of lesion suppression that uses an in vivo optical imaging technology for the initial screening of compounds. A strong correlation between luciferase activity and the parasite load at up to 18 days postinfection was found. This correlation allows the direct assessment of the effects of drug treatment on parasite burden. We demonstrate that there is a strong correlation between drug efficacy measured on day 18 postinfection and the suppression of lesion size by day 60 postinfection, which allows us to reach an accurate conclusion on drug efficacy in only 18 days. Compounds demonstrating a significant reduction in the bioluminescence signal compared to that in control animals can be tested in lower-throughput, more definitive tests of lesion cure in BALB/c mice and Golden Syrian hamsters (GSH) using Old World and New World parasites.

[Infectious exacerbation of chronic obstructive pulmonary disease: prospects for high-dose levofloxacin therapy].

This open comparative randomized study of efficacy, safety, and pharmacoeconomic characteristics of hilifox-750 (750 mg daily for 5 days) and amoxiclav 2X (875/125 mg twice daily for 10 days) included 60 patients with chronic obstructive pulmonary disease (COPD). Duration of the study was 6 months. Medians of age and smoking index in the group treated with hilifox-750 were 63.5 yr (59, 67) and 30 packs/yr (15, 60) respectively. The treatment reduced cough, apnea, sputum volume and pyoptysis with comparative rates of normalization of body temperature and peripheral leukocyte counts in both groups. Helifox-750 promoted decrease in coughing and apnea within the first three days of therapy. 28 (93%) and 26 (87%) patients recovered by day 4 of helifox and amoxiclav therapy (F-test p = 0.67). Both drugs showed comparable bacteriological efficacy. They were not different in terms of side effect frequency that were mild, resolved spontaneously and did not require withdrawal of therapy. Helifox had advantages over amoxiclav in that it reduced duration of antibacterial therapy to 5 days and of temporary incapacity to 12 days (vs 14); moreover, it needs to be taken only once daily.

Assessment of the combination of doripenem plus a fluoroquinolone against non-susceptible Acinetobacter baumannii isolates from nosocomial pneumonia patients.

Carbapenem- and fluoroquinolone-non-susceptible Acinetobacter baumannii were obtained from four nosocomial pneumonia patients who were clinically cured following combination therapy with doripenem/levofloxacin or ciprofloxacin. In vitro synergy of doripenem/levofloxacin or ciprofloxacin was evaluated using time-kill analysis. In vivo synergy was tested using a mouse lethal infection model. In time-kill studies, doripenem and levofloxacin were both bactericidal when tested at Cmax; at ½Cmax, the combination showed synergy up to 8 hours. Ciprofloxacin, alone or combined with doripenem, was not bactericidal. For mouse septicemia, doripenem (100 mg/kg) was ≥90% effective in preventing death in all four isolates. Levofloxacin (200 mg/kg) was 73% effective, and ciprofloxacin (35 mg/kg) was ineffective in preventing death. At lower drug concentrations, increased efficacy was observed for doripenem/levofloxacin, but not for doripenem/ciprofloxacin. Overall, the results suggest that a doripenem/levofloxacin combination may have clinical utility in treating some non-susceptible A. baumannii infections.

Optimizing biliary stent patency by coating with hydrophobin alone or hydrophobin and antibiotics or heparin: an in vitro proof of principle study.

PURPOSE: Although a wide range of biliary plastic and metal stents is on offer nowadays, the ideal cost-effective stent that functions permanently and that is easy to handle regarding its exchange is still not available. Therefore we tested in an in vitro model if the coating of plastic stents with hydrophobin alone or with hydrophobin and antibiotics or heparin in combination leads to an inhibition of the clogging process. METHODS: We coated commercially available biliary plastic stents with hydrophobin alone, as well as with hydrophobin and antibiotics or heparin in combination. After an incubation period of 28 days in human bile, we examined the stents by scanning electron microscopy to see whether the clogging material on its surface was reduced. RESULTS: Coating of plastic stents with hydrophobin led to a reduction in the amount of adherent material on the surface of the stents. Coupling of ampicillin/sulbactam or levofloxacin did not lead to a further reduction of the clogging material, whereas coupling with highly concentrated heparin did reduce the adherent material. CONCLUSIONS: The coating of biliary plastic stents with hydrophobin or with hydrophobin and heparin in combination seems to be a promising option to delay the clogging process.

Assessment of trends of ofloxacin resistance in Mycobacterium tuberculosis.

PURPOSE: Ofloxacin (OFX) is one of the potent fluoroquinolone (FQ) recommended to treat MDR-TB. Over a decade, the preexposure of this drug for the treatment of other bacterial infections has resulted in acquisition of FQ resistance among Mycobacterium tuberculosis strains. Considering this possibility, a study was undertaken in a tertiary care center in the capital city (India) to assess the drug resistance trends of OFX among susceptible and multidrug resistant (MDR) strains of M. tuberculosis. MATERIALS AND METHODS: A total of 102 M. tuberculosis isolates (47 susceptible to first-line drugs and 55 MDR isolates) were screened for susceptibility testing of OFX with a critical concentration of 2 µg/ml by Lowenstein Jensen (LJ) proportion method. RESULTS: The results showed 40 (85.1%) isolates among 47 susceptible isolates and 34 (61.8%) isolates among 55 MDR isolates, were found to be susceptible to OFX. Fisher's exact test showed significant P-value (0.0136) demonstrating 1.377 fold (95% confidence interval) increased risk to become resistant to OFX than susceptible isolates. These finding shows decreased OFX susceptibility is not only limited to MDR isolates but also increasingly seen in susceptible strains as a result of drug abuse. CONCLUSIONS: Our finding were not alarming, but highlights the general risk of acquiring resistance to OFX, jeopardizing the potential for these drugs to be used as second-line anti-TB agents in the management of drug-resistant TB and creating incurable TB strains .

Fluoroquinolones in the management of community-acquired pneumonia in primary care.

A literature search was conducted to evaluate the pharmacokinetic and pharmacodynamic profile of the respiratory fluoroquinolones (gemifloxacin, levofloxacin and moxifloxacin) and their efficacy and safety in the management of community-acquired pneumonia (CAP). Data show that CAP is a common presentation in primary care practice, and is associated with high rates of morbidity and mortality, particularly in the elderly. Although the causative pathogens differ depending on treatment setting and patient factors, Streptococcus pneumoniae is the primary pathogen in all treatment settings. As a class, the respiratory fluoroquinolones have a very favorable pharmacokinetic and pharmacodynamic profile. Pharmacodynamic criteria suggest that moxifloxacin and gemifloxacin are more potent against S. pneumoniae, which may have the added benefit of reducing resistance selection and enhancing bacterial eradication. The respiratory fluoroquinolones are also generally well tolerated, and are first-line options for outpatient treatment of CAP in patients with comorbidities or previous antibiotic use.

Sensitivity and proportionality assessment of metabolites from microdose to high dose in rats using LC-MS/MS.

BACKGROUND: The objective of this study was to evaluate the sensitivity requirement for LC-MS/MS as an analytical tool to characterize metabolites in plasma and urine at microdoses in rats and to investigate proportionality of metabolite exposure from a microdose of 1.67 µg/kg to a high dose of 5000 µg/kg for atorvastatin, ofloxacin, omeprazole and tamoxifen. RESULTS: Only the glucuronide metabolite of ofloxacin, the hydroxylation metabolite of omeprazole and the hydration metabolite of tamoxifen were characterized in rat plasma at microdose by LC-MS/MS. The exposure of detected metabolites of omeprazole and tamoxifen appeared to increase in a nonproportional manner with increasing doses. Exposure of ortho- and para-hydroxyatorvastatin, but not atorvastatin and lactone, increased proportionally with increasing doses. CONCLUSION: LC-MS/MS has demonstrated its usefulness for detecting and characterizing the major metabolites in plasma and urine at microdosing levels in rats. The exposure of metabolites at microdose could not simply be used to predict their exposure at higher doses.

Quantitative assessment of combination antimicrobial therapy against multidrug-resistant bacteria in a murine pneumonia model.

BACKGROUND: Combination antimicrobial therapy is clinically used as a last-resort strategy to control multidrug-resistant bacterial infections. However, selection of antibiotics is often empirical, and conventional assessment of combined drug effect has not been correlated to clinical outcomes. Here, we report a quantitative method to assess combined killing of antimicrobial agents against 2 multidrug-resistant bacteria. METHODS: Combined time-kill studies were performed using clinically achievable concentrations for each 2-agent combination against clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa. Bacterial burden observed at 24 h was mathematically modeled using a 3-dimensional response surface. Subsequently, a neutropenic murine pneumonia model with simulated clinical dosing exposures was used to validate our quantitative assessment of combined killing. RESULTS: Different antimicrobial combinations were found to have varying efficacy against the multidrug-resistant bacteria. As predicted by our quantitative method, cefepime plus amikacin was found to be the most superior combination, which was evidenced by a reduction in tissue bacterial burden and prolonged survival of infected animals. CONCLUSIONS: The consistency between the predictions of the mathematical model and in vivo observations substantiated the robustness of our quantitative method. These data highlighted a novel and promising method to guide rational selection of antimicrobial combination in the clinical setting.

Thin-layer agar for detection of resistance to rifampicin, ofloxacin and kanamycin in Mycobacterium tuberculosis isolates.

BACKGROUND: In low-income countries there is a great need for economical methods for testing the susceptibility of Mycobacterium tuberculosis to antibiotics. OBJECTIVE: To evaluate the thin-layer agar (TLA) for rapid detection of resistance to rifampicin (RMP), ofloxacin (OFX) and kanamycin (KM) in M. tuberculosis clinical isolates and to determine the sensitivity, specificity and time to positivity compared to the gold standard method. METHODS: One hundred and forty-seven clinical isolates of M. tuberculosis were studied. For the TLA method, a quadrant Petri plate containing 7H11 agar with RMP, OFX and KM was used. Results were compared to the Bactec MGIT960 for RMP and the proportion method for OFX and KM. RESULTS: The sensitivity and specificity for RMP and OFX were 100% and for KM they were 100% and 98.7%, respectively. The use of a TLA quadrant plate enables the rapid detection of resistance to the three anti-tuberculosis drugs RMP, OFX and KM in a median of 10 days. CONCLUSION: TLA was an accurate method for the detection of resistance in the three drugs studied. This faster method is simple to perform, providing an alternative method when more sophisticated techniques are not available in low-resource settings.

[Biological cost of rifampicin resistance in Helicobacter pylori].

The frequence of mutations in the rifampicin resistant (RIF(r)) clones of microorganisms after adaption to ofloxacin and metronidazole was investigated to estimate the biological cost of H. pylori rifampicin (RIF) resistance. Mutations in rpoB gene responsible for RIF resistance of H. pylori were shown to have biological cost and be compensated by additional mutations in the microorganism genome. Comparison of the mutation frequency in the presence of metroniazole demonstrated that the acquired resistance to RIF resulted in changing of the adaptative capacity of the RIF(r) clones of H. pylori to metronidazole. Thus, a significant increase of the mutation frequency (> 700 times) in one of the RIF(r) clones and a broad spectrum of the mutations responsible for resistance to metronidazole vs. the H. pylori initial strain 26695 were observed. The findings could be evident of the fact that the adaptation to RIF changed the properties of the cell on one hand in such a way that its mutation capacity increased and that the target selection on the other hand revealed hypermutable cells, likely usual for the bacterial population.

Quantitative assessment of combination antimicrobial therapy against multidrug-resistant Acinetobacter baumannii.

Treatment of multidrug-resistant bacterial infections poses a therapeutic challenge to clinicians; combination therapy is often the only viable option for multidrug-resistant infections. A quantitative method was developed to assess the combined killing abilities of antimicrobial agents. Time-kill studies (TKS) were performed using a multidrug-resistant clinical isolate of Acinetobacter baumannii with escalating concentrations of cefepime (0 to 512 mg/liter), amikacin (0 to 256 mg/liter), and levofloxacin (0 to 64 mg/liter). The bacterial burden data in single and combined (two of the three agents with clinically achievable concentrations in serum) TKS at 24 h were mathematically modeled to provide an objective basis for comparing various antimicrobial agent combinations. Synergy and antagonism were defined as interaction indices of <1 and >1, respectively. A hollow-fiber infection model (HFIM) simulating various clinical (fluctuating concentrations over time) dosing exposures was used to selectively validate our quantitative assessment of the combined killing effect. Model fits in all single-agent TKS were satisfactory (r(2) > 0.97). An enhanced combined overall killing effect was seen in the cefepime-amikacin combination (interactive index, 0.698; 95% confidence interval [CI], 0.675 to 0.722) and the cefepime-levofloxacin combination (interactive index, 0.929; 95% CI, 0.903 to 0.956), but no significant difference in the combined overall killing effect for the levofloxacin-amikacin combination was observed (interactive index, 0.994; 95% CI, 0.982 to 1.005). These assessments were consistent with observations in HFIM validation studies. Our method could be used to objectively rank the combined killing activities of two antimicrobial agents when used together against a multidrug-resistant A. baumannii isolate. It may offer better insights into the effectiveness of various antimicrobial combinations and warrants further investigations.

Simulated comparison of the pharmacodynamics of ciprofloxacin and levofloxacin against Pseudomonas aeruginosa using pharmacokinetic data from healthy volunteers and 2002 minimum inhibitory concentration data.

BACKGROUND: Until the 2002 approval of levofloxacin 750 mg QD, ciprofloxacin was the fluoroquinolone of choice against Pseudomonas aeruginosa infections. OBJECTIVE: This study evaluated the AUC:MIC ratios for ciprofloxacin 400 mg BID and TID and levofloxacin 750 mg QD, all administered intravenously, against P. aeruginosa using a Monte Carlo simulation. METHODS: Pharmacokinetic data for ciprofloxacin and levofloxacin and 2002 MIC distributions against P. aeruginosa were obtained from studies in healthy volunteers published in the peer-reviewed literature. Pharmacokinetic studies of each agent were identified by separate MEDLINE searches combining the MeSH heading pharmacokinetics with the generic name of the antimicrobial. Only human studies published in English between 1990 and 2001 were included. Included studies also had to meet 3 minimum criteria: evaluation of clinically relevant dosing regimens, use of rigorous study methods, and provision of mean (SD) values for the pharmacokinetic parameters of interest. When multiple studies met these criteria, a single study was selected for each antimicrobial regimen. Pharmacodynamic analysis was performed using a Monte Carlo simulation of 10,000 patients by integrating the pharmacokinetic parameters, their variability, and 2002 MIC distributions for each antimicrobial regimen. The probability of target attainment was determined for each regimen for an AUC:MIC ratio from 0 to 300. A > or =90% probability of target attainment was considered satisfactory. RESULTS: For ciprofloxacin 400 mg TID and levofloxacin 750 mg QD, the AUC:MIC ratio at the corresponding 2002 Clinical Laboratory Standards Institute break points of 1 and 2 microg/mL were 33 and 34, respectively. The probabilities of target attainment for a free AUC:MIC ratio >90 (equivalent to a total AUC:MIC ratio > or =125) were 47% for ciprofloxacin 400 mg BID, 54% for ciprofloxacin 400 mg TID, and 48% for levofloxacin 750 mg QD. CONCLUSION: When pharmacokinetic data from healthy volunteers and 2002 MIC data were used, none of the simulated fluoroquinolone regimens achieved a high likelihood of target attainment against P. aeruginosa.

Pharmacodynamic assessment based on mutant prevention concentrations of fluoroquinolones to prevent the emergence of resistant mutants of Streptococcus pneumoniae.

The objective of this study was to investigate the relationship between pharmacokinetic and pharmacodynamic parameters, on the basis of the mutant prevention concentration (MPC) concept, and the emergence of resistant mutants of Streptococcus pneumoniae to fluoroquinolone antibacterials. Some clinical isolates with various MIC and MPC values of moxifloxacin and levofloxacin were exposed under conditions simulating the time-concentration curves observed when moxifloxacin (400 or 80 mg, once a day) or levofloxacin (200 mg, twice a day) was orally administered by using an in vitro pharmacodynamic model. The decrease in susceptibility was evaluated by altering the population analysis profiles after moxifloxacin or levofloxacin treatment for 72 h. When the area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MPC and peak concentration (C(max))/MPC were above 13.41 and 1.20, respectively, complete eradication occurred and no decrease in susceptibility was observed. On the other hand, when AUC(0-24)/MPC and C(max)/MPC were below 0.84 and 0.08, respectively, the susceptibility decreased. However, the time inside the mutant selective window and the time above the MPC did not show any correlation with the decrease in susceptibility. These results suggest that AUC(0-24)/MPC and C(max)/MPC are important parameters for predicting the emergence of resistant mutants and that higher values indicate greater effectiveness.

Cross-over assessment of serum bactericidal activity of moxifloxacin and levofloxacin versus penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae in healthy volunteers.

We compared the serum bactericidal activity (SBA) of moxifloxacin and levofloxacin against penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae in 12 healthy volunteers. Each subject received 3 days of oral moxifloxacin 400 mg daily and levofloxacin 750 mg daily, respectively, with a 2- to 4-week washout period between regimens. Blood was drawn at 6 time points after the third dose of each antibiotic. Mean serum bactericidal titers (MSBTRs) for moxifloxacin were 4-fold higher than the mean titers for levofloxacin at each time point. For each drug, MSBTRs at each time point were the same or within one 2-fold dilution when analyzed according to the penicillin susceptibility of the strains or the sex of the subjects. The difference in SBA of the 2 drugs may have implications for the emergence of resistance and clinical outcome.

In vitro activity of prulifloxacin against Escherichia coli isolated from urinary tract infections and the biological cost of prulifloxacin resistance.

Minimum inhibitory concentrations (MICs) and mutant prevention concentrations (MPCs) of prulifloxacin against 30 strains of Escherichia coli isolated from urinary tract infections as well as the 'biological cost' related to acquisition of resistance to the same drug in 10 uropathogenic E. coli were assessed. In terms of MIC(90), prulifloxacin was more potent than ciprofloxacin and levofloxacin. Prulifloxacin produced lower or equal MPC values than the other two fluoroquinolones (93.3% and 73.3% compared with levofloxacin and ciprofloxacin, respectively). Compared with susceptible strains, prulifloxacin-resistant mutants showed a reduced rate of growth (ranging from 20.0% to 98.0% in different culture media and incubation conditions) and a decreased fitness index (ranging from 0.959 to 0.999). They were also impaired in their ability to adhere to uroepithelial cells and urinary catheters (11.7-66.4% and 16.3-78.3% reduction, respectively) and showed a lower surface hydrophobicity (51.2-76.0%). They were more susceptible to ultraviolet irradiation (30.6-93.8% excess mortality), showed increased resistance to colicins and diminished transfer of plasmids (<1-8.5x10(-8) vs. 3.3x10(-7)-2.4x10(-4)). Synthesis of haemolysin and type I fimbriae and production of flagella were also adversely affected. This study demonstrates a strict relationship between acquisition of prulifloxacin resistance and loss of important virulence traits. In this transition, E. coli pays a severe biological cost that entails a general reduction of fitness, thus compromising competition with susceptible wild-type strains in the absence of the drug.

A community-based study of Helicobacter pylori therapy using the strategy of test, treat, retest, and re-treat initial treatment failures.

BACKGROUND: Although eradication of Helicobacter pylori infection can decrease the risk of gastric cancer, the optimal regimen for treating the general population remains unclear. We report the eradication rate (intention-to-treat and per protocol) of a community-based H. pylori therapy using the strategy of test, treat, retest, and re-treat initial treatment failures. MATERIALS AND METHODS: In 2004, a total of 2658 residents were recruited for 13C-urea breath testing. Participants with positive results for infection received a standard 7-day triple therapy (esomeprazole 40 mg once daily, amoxicillin 1 g twice daily, and clarithromycin 500 mg twice daily), and a 10-day re-treatment (esomeprazole 40 mg once daily, amoxicillin 1 g twice daily, and levofloxacin 500 mg once daily) if the follow-up tests remained positive. Both H. pylori status and side-effects were assessed 6 weeks after treatment. RESULTS: Among 886 valid reporters, eradication rates with initial therapy were 86.9% (95% confidence interval [CI]: 84.7-89.1%) and 88.7% (95%CI: 86.5-90.9%) by intention-to-treat and per protocol analysis, respectively. Re-treatment eradicated infection in 91.4% (95%CI: 86-96.8%) of 105 nonresponders. Adequate compliance was achieved in 798 (90.1%) of 886 subjects receiving the initial treatment and in all 105 re-treated subjects. Mild side-effects occurred in 24% of subjects. Overall intention-to-treat and per protocol eradication rates were 97.7% (95%CI: 96.7-98.7%) and 98.8% (95%CI: 98.5-99.3%), respectively, which were only affected by poor compliance (odds ratio, 3.3; 95%CI, 1.99-5.48; p < .0001). CONCLUSIONS: A comprehensive plan using drugs in which the resistance rate is low in a population combined with the strategy of test, treat, retest, and re-treat of needed can result in virtual eradication of H. pylori from a population. This provides a model for planning country- or region-wide eradication programs.