Urinary bactericidal activity of Doripenem versus that of levofloxacin in patients with complicated urinary tract infections or pyelonephritis

Evaluation of Efficacy of Fosfomycin for the Treatment of Patients with Lower Urinary Tract Infections (UTIs)

Introduction: Until now, there have been few investigations on the efficacy of fosfomycin in the treatment of patients with uncomplicated urinary tract infections (UTIs). The present study is aimed to examine how fosfomycin affects females with lower UTIs. Methods:A total of 200 female patients who visited the women's clinic at Amir-Al-Momenin Hospital between 2020 and 2021 were examined in the present study. Patients were randomly divided into two groups of 100 people each, with one group receiving fosfomycin (a single 3 g dose) and the other one receiving cephalexin (a five-day regimen at 0.5 g four times daily). Then, one week and one month after treatment, the patients underwent a urine culture test. The data were collected and further analyzed in SPSS statistics software version 26. Results:According to the study findings, the mean age of females suffering from lower UTI was 25.45 ± 5.85 years. Besides, the collected data revealed that 85.5% of females diagnosed with lower UTI had E. coli. In addition, the frequency of females with Staphylococcus saprophyticus, Proteus spp and Klebsiella were 9%, 3% and 2.5%, respectively. Also, the frequency of women with UTI for E. coli, Staphylococcus saprophyticus, Proteus spp and Klebsiella were 85.5%, 9%, 3.2% and 2.5%, respectively. One month after treatment, urine culture showed positive results in 98% of patients who were treated with fosfomycin and 95% of those who received cephalexin. Conclusion:Fosfomycin can be administrated to treat uncomplicated UTIs in women with a high level of confidence, as an alternative to cephalexin.

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

A Meta-Analysis on Clinical Outcomes of Ceftolozane versus Piperacillin in Combination with Tazobactam in Patients with Complicated Urinary Tract Infections

Objective

To evaluate efficacy and adverse events of ceftolozane/tazobactam in complicated UTI including acute pyelonephritis.

Method

Databases that include PubMed, Embase, Scopus, and TRIP were searched. All randomized controlled trials and cohort studies were considered for the study. Statistical analysis was done using a fixed effects model, and results were expressed in proportion for dichotomous data and risk ratio for continuous data with 95% confidence intervals (CI).

Results

A clinical cure of ceftolozane/tazobactam was found to be 92% with 95% CI of 90-94 while that of piperacillin/tazobactam was only 78% (95% CI, 74-82) in patients with complicated UTI. Microbiological eradication was still higher in the ceftolozane/tazobactam group (83%, 95% CI 81-88) when compared with piperacillin/tazobactam (63% 95% CI, 58.77-65.2). Ceftolozane/tazobactam was more effective in the treatment of complicated urinary tract infections other than acute pyelonephritis as compared to piperacillin/tazobactam (RR = 1.21, 95% CI, 1.07-1.23). Serious adverse events were found comparable in both groups (RR = 1.15, 95% CI, 0.64-2.09).

Conclusion

The analysis showed that ceftolozane/tazobactam has better clinical outcomes including cure rates and low resistance for the treatment of complicated urinary tract infection.

Pharmacokinetics and Safety of Doripenem in Healthy Chinese Subjects and Monte Carlo Dosing Simulations

The aim of this study was to investigate the pharmacokinetics (PK) of doripenem in healthy Chinese subjects and evaluate the optimal dosage regimens of doripenem. A randomized, single-dose, three-period, self-crossover controlled extended-infusion clinical trial was conducted with 12 healthy Chinese subjects. Plasma and urine samples were collected to determine doripenem concentrations. Non-compartmental and population PK analysis were performed to characterize the PK of doripenem. The Monte Carlo simulation was employed to optimize dosing regimens based on the probability of target attainment of doripenem against pathogens with different minimum inhibitory concentrations (MIC). All 12 healthy Chinese subjects completed the study, and the doripenem was well tolerated. The study showed linearity relationships in the peak plasma concentration and the area under the concentration-time curve after intravenous infusion of doripenem from 0.25 g to 1.0 g. The cumulative urinary recovery rate of doripenem was 68.1–72.0% within 24 h. PPK modeling showed a two-compartmental model, with first-order elimination presenting the best fit for doripenem PK. Monte Carlo simulation results showed that 1.0 g q12h or 0.5 g q8h was an optimal regimen for pathogens susceptible to doripenem (MIC ≤ 1 mg/L); while high dose and extended infusion (1 g, q8h, 4 h infusion) was proposed for unsusceptible pathogens (2 ≤ MIC ≤ 8 mg/L). In the dose range of 0.25 to 1.0 g, doripenem showed linear pharmacokinetics. Doripenem at 1.0 g with a prolonged infusion time of 4 h was predicted to be effective against pathogens with MICs as high as 8 mg/L.

Fluoroquinolone Can Be an Effective Treatment Option for Acute Pyelonephritis When the Minimum Inhibitory Concentration of Levofloxacin for the Causative Escherichia coli Is ≤16 mg/L

The purpose of this study was to determine whether the fluoroquinolone (FQ) minimum inhibitory concentration (MIC) for the causative agent Escherichia coli influences the clinical response of FQ treatment at 72 h in patients with community-acquired acute pyelonephritis (CA-APN). We prospectively collected the clinical data of women with CA-APN from 11 university hospitals from March 2010 to February 2012 as well as E. coli isolates from the urine or blood. In total, 78 patients included in this study received FQ during the initial 72 h, and the causative E. coli was detected. The clinical response at 72 h was significantly higher in patients with a levofloxacin MIC ≤ 16 mg/L than in those with an MIC > 16 mg/L (70.4% vs. 28.6%, p = 0.038). No difference was observed in clinical response at 72 h based on ciprofloxacin MIC. To summarize, FQ can be an effective treatment option for CA-APN when levofloxacin MIC against E. coli is ≤16 mg/L.

A Critical Review of Cephalexin and Cefadroxil for the Treatment of Acute Uncomplicated Lower Urinary Tract Infection in the Era of "Bad Bugs, Few Drugs"

First-generation oral cephalosporins (cephalexin and cefadroxil) have traditionally been considered second-line treatment options for uncomplicated lower urinary tract infections (uLUTIs).  However, in the current age of "bad bugs, few drugs", where there are increasingly limited oral options against resistant Enterobacteriaceae, there is an urgent need to rethink how best to utilize the available antibiotic armamentarium.  This review examines the historical clinical trials and experimental studies of cephalexin and cefadroxil, particularly through the modern lens of pharmacokinetics/pharmacodynamics (PK/PD), to better appreciate the efficacy of these drugs in uLUTIs.  Furthermore, newer cefazolin-cephalexin surrogate testing, as recommended by the Clinical and Laboratory Standards Institute (CLSI) and the United States Committee on Antimicrobial Susceptibility Testing (USCAST), has recategorized cephalexin in many instances from resistant to susceptible.  We conclude that cephalexin and cefadroxil have very good early bacteriological and clinical cures in uLUTIs due to non-extended-spectrum beta-lactamase-producing (ESBL) Enterobacteriaceae comparable to many traditionally first-line agents.  Cephalexin can be conveniently administered as 500 mg twice or thrice daily, similar to cefadroxil (500 mg twice daily); therefore, either agent may be used as a fluoroquinolone-sparing alternative. Cephalexin may be the more practical choice for many clinicians because reliable antimicrobial susceptibility test interpretative criteria (STIC) are provided by CLSI, USCAST, and the European Committee on Antimicrobial Susceptibility Testing (EUCAST), whereas direct cefadroxil STIC is offered only by EUCAST.

Urinary Pharmacokinetic and Pharmacodynamic Profiles of Fosfomycin against Extended-Spectrum β-Lactamase-Producing Escherichia coli with Canine Ex Vivo Modeling: A Pilot Study

Fosfomycin is a candidate drug for extended-spectrum β-lactamase (ESBL)-producing bacteria, but its efficacy is yet to be investigated in dogs. This study investigated the urinary pharmacokinetic/pharmacodynamic (PK/PD) profile of fosfomycin orally administered at 80 mg/kg to six healthy dogs to assess its efficacy for canine urinary tract infections (UTIs) caused by ESBL-producing bacteria. Four strains of ESBL-producing Escherichia coli (ESBL-EC) characterized by fosfomycin minimum inhibitory concentrations (MICs) of 0.5, 1, 2, and 32 µg/mL were used. Urine samples for the measurement of urinary drug concentrations and urinary bactericidal titers (UBTs) were obtained after drug administration. The urinary concentrations (µg/mL, mean ± SE) were 1348.2 ± 163.5, 1191.6 ± 260.2, and 661.1 ± 190.4 at 0-4, 4-8, and 8-12 h, respectively, after drug administration. The mean urinary area under the curve during the test period (AUC0-12) of fosfomycin was estimated to be 12,803.8 µg·h/mL. The UBTs for all tested strains fluctuated closely with urine concentration during the test period (r = 0.944-1.000), and the area under the UBT-versus-time curve correlated with the urinary AUC/MIC of each strain (r = 0.991). According to the optimal urinary PK/PD target value, fosfomycin at 80 mg/kg twice daily may be suitable for the treatment of canine UTIs caused by ESBL-EC presenting MIC ≤ 128 µg/mL.

Calculated parenteral initial treatment of bacterial infections: Infections of the kidneys and the genito-urinary tract

This is the eighth chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. The chapter deals with the treatment of more severe infections of the kidney and the urogenital tract, including urosepsis. Recommendations for empiric and targeted antibacterial treatment are given.

Ex Vivo Urinary Bactericidal Activity and Urinary Pharmacodynamics of Fosfomycin after Two Repeated Dosing Regimens of Oral Fosfomycin Tromethamine in Healthy Adult Subjects

The ex vivo bactericidal activity and pharmacodynamics of fosfomycin in urine were evaluated in 18 healthy subjects. Subjects received 3 g every other day (QOD) for 3 doses and then every day (QD) for 7 doses or vice versa. Serial urine samples were collected before and up to 24 h after dosing on days 1 and 5. Eight bacterial strains with various genotypic and phenotypic susceptibilities to fosfomycin were used for all experiments (5 Escherichia coli, 2 Klebsiella pneumoniae, and 1 Proteus mirabilis). MICs were performed via agar dilution. Urinary bactericidal titers (UBTs) were performed via modified Schlichter test using participant's drug-free urine as the diluent. Urinary time-kill analyses were performed on pooled 24-h urine aliquots from days 1 and 5. All experiments were performed in triplicate with and without the addition of 25 mg/liter of glucose-6-phosphate (G6P). Mean 24-h urine concentrations of fosfomycin ranged from 324.7 to 434.6 mg/liter regardless of study day or dosing regimen. The urinary antibacterial activity of fosfomycin was also similar across study days and dosing regimens. UBT values did not correlate with MICs determined in the presence of G6P. Fosfomycin was reliably bactericidal in urine only against the 5 E. coli strains, regardless of genotype or MIC value. Together, these data do not support the use of oral fosfomycin tromethamine for pathogens other than E. coli or at a dosing frequency higher than QOD. Fosfomycin MICs determined in the presence of G6P may not accurately reflect the in vivo activity given the lack of G6P in human urine. (This study has been registered at ClinicalTrials.gov under identifier NCT02570074.).

Assessment of urinary pharmacokinetic and pharmacodynamic profiles of faropenem against extended-spectrum β-lactamase-producing Escherichia coli with canine ex vivo modelling: a pilot study

This study was carried out to investigate the urinary pharmacokinetics and pharmacodynamics of faropenem administered orally at 5 mg kg^-1 in six healthy dogs to assess the efficacy of the drug for canine urinary tract infections (UTIs) with extended-spectrum β-lactamase (ESBL)-producing bacteria. Six strains of ESBL-producing Escherichia coli (ESBL-EC) with the following faropenem minimum inhibitory concentrations (MICs) were used: 1 µg ml^-1 (n=2), 2 µg ml^-1 (n=2), 4 µg ml^-1 (n=1) and 16 µg ml^-1 (n=1). Urine samples were obtained every 4 h for the first 12 h after administration to measure urinary drug concentration and urinary bactericidal titres (UBTs). Both the urine concentration of faropenem and the UBTs for all tested strains peaked at 0-4 h after administration, and decreased markedly at 8-12 h. The mean urinary concentration of faropenem at 8-12 h (23±5.2 µg ml^-1) exceeded the MIC of 1 µg ml^-1 by fourfold, which is required to inhibit the growth of 90  % of ESBL-EC. These findings indicate that faropenem administered twice daily at a dose of 5 mg kg^-1 is acceptable for the treatment of most dogs with ESBL-EC-related UTIs.

Assessment of urinary pharmacokinetics and pharmacodynamics of orbifloxacin in healthy dogs with ex vivo modelling

PURPOSE

The aim of this study was to investigate the urinary pharmacokinetics (PK) of orbifloxacin (OBFX) administered at 5 mg kg-1 in six healthy dogs. A further aim was to use an ex vivo model to evaluate the urinary PK and pharmacodynamics (PD) of OBFX to determine its urinary bactericidal titre (UBT), which represents the maximal dilution of urine allowing bactericidal activity.

METHODOLOGY

Fourteen urinary tract infection (UTI) pathogenic strains of five bacterial species (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis and Staphylococcuspseudintermedius) were used. Urine samples were obtained every 4 h for the first 24 h after OBFX administration, for measurement of urine drug concentration and UBT.Results/Key findings. The urine OBFX concentration peaked at 0-4, 4-8 or 4-8 h after administration, with a maximum concentration of 383±171 µg ml-1. Overall, the fluctuation in median UBT closely correlated with that of the mean urine OBFX concentration. In addition, the median areas under the UBT-time curves (AUBTs) were significantly inversely correlated with the MICs for OBFX in the tested strains (P<0.01). Notably, median UBTs and AUBTs were extremely low (0-0.5 and 2-5, respectively) in OBFX-resistant E. coli strains with MIC ≥8 µg ml-1.

CONCLUSION

The fluctuation of UBTs closely correlated with that of urine concentration, and UBT values depended on the susceptibility of the bacterial strains to OBFX. We believe that ex vivo modelling to determine UBTs is useful to evaluate the urinary PK/PD of antimicrobials indicated for UTIs in dogs.

Urosepsis: Overview of the Diagnostic and Treatment Challenges

Urosepsis is defined as sepsis caused by an infection in the urogenital tract. In approximately 30% of all septic patients the infectious focus is localized in the urogenital tract, mainly due to obstructions at various levels, such as ureteral stones. Urosepsis may also occur after operations in the urogenital tract. In urosepsis, complete bacteria and components of the bacterial cell wall from the urogenital tract trigger the host inflammatory event and act as exogenous pyrogens on eukaryotic target cells of patients. A burst of second messenger molecules leads to several different stages of the septic process, from hyperactivity to immunosuppression. As pyelonephritis is the most frequent cause for urosepsis, the kidney function is therefore most important in terms of cause and as a target organ for dysfunction in the course of the sepsis.Since effective antimicrobial therapy must be initiated early during sepsis, the empiric intravenous therapy should be initiated immediately after microbiological sampling. For the selection of appropriate antimicrobials, it is important to know risk factors for resistant organisms and whether the sepsis is primary or secondary and community or nosocomially acquired. In addition, the preceding antimicrobial therapies should be recorded as precisely as possible. Resistance surveillance should, in any case, be performed locally to adjust for the best suitable empiric treatment. Treatment challenges arise from the rapid increase of antibiotic resistance in Gram-negative bacteria, especially extended-spectrum β-lactamase (ESBL)-producing bacteria. Treatment of urosepsis comprises four basic strategies I) supportive therapy (stabilizing and maintaining blood pressure), II) antimicrobial therapy, III) control or elimination of the complicating factor, and IV) specific sepsis therapy.

Ceftazidime-avibactam Versus Doripenem for the Treatment of Complicated Urinary Tract Infections, Including Acute Pyelonephritis: RECAPTURE, a Phase 3 Randomized Trial Program

BACKGROUND

The global emergence of carbapenem-resistant Enterobacteriaceae highlights the urgent need to reduce carbapenem dependence. The phase 3 RECAPTURE program compared the efficacy and safety of ceftazidime-avibactam and doripenem in patients with complicated urinary tract infection (cUTI), including acute pyelonephritis.

METHODS

Hospitalized adults with suspected or microbiologically confirmed cUTI/acute pyelonephritis were randomized 1:1 to ceftazidime-avibactam 2000 mg/500 mg every 8 hours or doripenem 500 mg every 8 hours (doses adjusted for renal function), with possible oral antibiotic switch after ≥5 days (total treatment duration up to 10 days or 14 days for patients with bacteremia).

RESULTS

Of 1033 randomized patients, 393 and 417 treated with ceftazidime-avibactam and doripenem, respectively, were eligible for the primary efficacy analyses; 19.6% had ceftazidime-nonsusceptible baseline pathogens. Noninferiority of ceftazidime-avibactam vs doripenem was demonstrated for the US Food and Drug Administration co-primary endpoints of (1) patient-reported symptomatic resolution at day 5: 276 of 393 (70.2%) vs 276 of 417 (66.2%) patients (difference, 4.0% [95% confidence interval {CI}, -2.39% to 10.42%]); and (2) combined symptomatic resolution/microbiological eradication at test of cure (TOC): 280 of 393 (71.2%) vs 269 of 417 (64.5%) patients (difference, 6.7% [95% CI, .30% to 13.12%]). Microbiological eradication at TOC (European Medicines Agency primary endpoint) occurred in 304 of 393 (77.4%) ceftazidime-avibactam vs 296 of 417 (71.0%) doripenem patients (difference, 6.4% [95% CI, .33% to 12.36%]), demonstrating superiority at the 5% significance level. Both treatments showed similar efficacy against ceftazidime-nonsusceptible pathogens. Ceftazidime-avibactam had a safety profile consistent with that of ceftazidime alone.

CONCLUSIONS

Ceftazidime-avibactam was highly effective for the empiric treatment of cUTI (including acute pyelonephritis), and may offer an alternative to carbapenems in this setting.

CLINICAL TRIALS REGISTRATION

NCT01595438; NCT01599806.

Urinary Concentrations and Antibacterial Activity of BAL30072, a Novel Siderophore Monosulfactam, against Uropathogens after Intravenous Administration in Healthy Subjects

This annex study to a phase 1 study aimed to correlate urinary concentrations and bactericidal titers (UBTs) of BAL30072, a novel siderophore monosulfactam, in healthy subjects in order to evaluate which dosage of BAL30072 should be investigated in a clinical study on complicated urinary tract infection (UTI). Three cohorts of a total of 19 healthy male subjects were included in the add-on study and received the following BAL30072 dosages. The 1st cohort received 1 g once a day (q.d.) intravenously (i.v.) (1 h) on day 1 and 1 g thrice daily (t.i.d.) on day 2, the 2nd cohort received 2 g q.d. i.v. (1 h) on day 1 and 2 g t.i.d. on day 2, and the 3rd cohort received 1 g q.d. i.v. (4-h infusion) on day 8. Urine was collected up to 24 h after drug administration. UBTs were determined for seven Escherichia coli isolates (three wild type [WT], CTX-M-15, TEM-3, TEM-5, NDM-1), two Klebsiella pneumoniae isolates (WT, KPC), one Proteus mirabilis isolate (WT), and two Pseudomonas aeruginosa isolates (WT, VIM-1 plus AmpC). Urine drug concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The median urinary excretions of BAL30072 ranged between 38% and 46% (3 cohorts). The median UBTs after i.v. administration of 1 or 2 g q.d. and after 1 or 2 g t.i.d. showed positive UBTs for 24 h after the lowest dosage (1 g q.d.) for 5 of 7 of the Enterobacteriaceae strains and after the higher dosage of 2 g administered i.v. t.i.d. for all strains tested. After i.v. infusion of 1 g over 4 h, positive UBTs were demonstrated for three E. coli strains for up to 12 h, for the K. pneumoniae (KPC) strain for up to 8 h, and for the P. aeruginosa (VIM-1 plus AmpC) strain for up to only 4 h. The minimal bactericidal concentrations (MBCs) of the E. coli (NDM-1) strain and the K. pneumoniae (WT) strain correlated well between broth and urine but did not correlate well for the two P. aeruginosa strains. BAL30072 exhibits positive UBTs for 24 h even after a dosage of 1 g administered i.v. q.d. for 5 of 7 Enterobacteriaceae strains and after 2 g administered i.v. t.i.d. for all strains except one P. aeruginosa strain (50% of the time). In general, the UBTs correlated well with the MICs of the Enterobacteriaceae but were lower for P. aeruginosa The clinical efficacy with a dosage regimen of BAL30072 of 2 g administered i.v. t.i.d. should be evaluated in the treatment of complicated UTI.

Urinary concentrations and antibacterial activities of nitroxoline at 250 milligrams versus trimethoprim at 200 milligrams against uropathogens in healthy volunteers

Because of the increasing bacterial resistance of uropathogens against standard antibiotics, such as trimethoprim (TMP), older antimicrobial drugs, such as nitroxoline (NTX), should be reevaluated. This randomized crossover study investigated the urinary concentrations of parent drugs and their metabolites and their antibacterial activities (urinary inhibitory titers [UITs] and urinary bactericidal titers [UBTs]) against uropathogens at three different urinary pH values within 24 h in six healthy volunteers after a single oral dose of NTX at 250 mg versus TMP at 200 mg. In three additional volunteers, urinary bactericidal kinetics (UBK) were studied after oral administration of NTX at 250 mg three times a day. The mean urinary concentrations of NTX and NTX sulfate in 24 h were 0.012 to 0.507 mg/liter and 0.28 to 27.83 mg/liter, respectively. The mean urinary concentrations of TMP were 18.79 to 41.59 mg/liter. The antibacterial activity of NTX was higher in acidic urine than in alkaline urine, and that of TMP was higher in alkaline urine than in acidic urine. The UITs and UBTs of NTX were generally lower than those of TMP except for a TMP-resistant Escherichia coli strain, for which NTX showed higher UITs/UBTs than did TMP. UBK showed mainly bacteriostatic activity of NTX in urine. NTX exhibits mainly bacteriostatic activity and TMP also shows bactericidal activity in urine against susceptible strains. NTX is a more active antibacterial in acidic urine, and TMP is more active in alkaline urine. The cumulative effects of multiple doses or inhibition of bacterial adherence could not be evaluated. (This study has been registered at EudraCT under registration no. 2009-015631-32.).

Emerging resistance problems and future perspectives in pharmacotherapy for complicated urinary tract infections

INTRODUCTION

Urinary tract infections (UTIs) are among the most common infectious diseases and contribute to high financial burden worldwide. Administration of appropriate antibiotic therapy is the key to achieving good therapeutic outcomes. The authors review the current status of global or regional epidemiology, especially on the antimicrobial resistance and several potential agents against complicated UTIs by multidrug-resistant (MDR) pathogens.

AREAS COVERED

The authors summarized the susceptibility status on several major surveillance programs on uropathogens, focusing on Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci. Besides, the current perspectives of several potential antimicrobials against MDR uropathogens available for UTIs were also reviewed.

EXPERT OPINION

High resistance to broad-spectrum antibiotics, especially to extended-spectrum β-lactams, carbapenems, and fluoroquinolones among uropathogens emerges as a critical problem in many countries. Appropriate antimicrobial stewardship and continuous surveillance are necessary to monitor the trends of susceptibility for main pathogens. For these MDR uropathogens, polymyxin, fosfomycin, tigecycline, nitrofurantoin, linezolid, and daptomycin might be potential treatments for patients with uncomplicated and complicated UTIs in some countries, although they might not be approved by their regulation. However, more clinical evidence and more extensive meta-analyses are needed to evaluate and confirm the effectiveness of their usage in countries with a high prevalence of multidrug resistance.

The role of fluoroquinolones in the management of urinary tract infections in areas with high rates of fluoroquinolone-resistant uropathogens

Fluoroquinolones have been recommended as the drugs of choice for the empirical treatment of uncomplicated and complicated urinary tract infections (UTIs) caused by trimethoprim-sulfamethoxazole-resistant uropathogens. However, because of the increased use of both oral and parenteral fluoroquinolones for other kinds of infections, increasing rates of resistance to fluoroquinolones among the most common uropathogens have challenged this recommendation, particularly in the Asia-Pacific region. The current interpretative criteria for the in vitro susceptibility of uropathogens to some fluoroquinolones, such as levofloxacin and ciprofloxacin, are set according to their therapeutic efficacy for bloodstream infections, and are not specific to UTIs. Fluoroquinolones exhibit concentration-dependent antibacterial activity, high renal excretion, and relatively early and prolonged urinary bactericidal titers. Whether or not current interpretative criteria for the in vitro susceptibility of uropathogens to fluoroquinolones predict clinical failure in treating UTIs is still controversial. The Clinical and Laboratory Standards Institute (CLSI) has established UTI-specific breakpoints for resistance to a few fluoroquinolones. However, the application of high-dose fluoroquinolone therapy for the treatment of mild to moderate UTIs caused by isolates with higher minimum inhibitory concentrations (MICs) of several fluoroquinolones needs to be re-validated based on more relevant clinical studies, prudent pharmacokinetic/pharmacodynamic (PK/PD) considerations, and thorough study of the mutant prevention concentration of fluoroquinolones in the treatment of UTI.

Doripenem: a new carbapenem antibiotic

PURPOSE

The chemistry, pharmacology, antimicrobial activity, pharmacokinetics, pharmacodynamics, efficacy and safety in humans, and formulary considerations of doripenem are reviewed.

SUMMARY

Doripenem, a member of the β-lactam class of antibiotics, is the newest addition to the carbapenems. It exhibits concentration-independent bactericidal activity against gram-positive bacteria; enteric and nonenteric gram-negative bacteria, including extended-spectrum β-lactamase-producing strains; and anaerobic pathogens. Doripenem was found to be noninferior to meropenem in the treatment of complicated intraabdominal infections and noninferior to levofloxacin in the treatment of complicated urinary tract infections including pyelonephritis and was granted marketing approval by the Food and Drug Administration for these two indications. Doripenem was also found to be noninferior to imipenem in the treatment of ventilator-associated pneumonia and noninferior to piperacillin-tazobactam in the treatment of hospital-acquired pneumonia. It has a favorable safety profile, with gastrointestinal complaints and headache being the most common adverse effects and allergic reactions the most serious adverse effects. Doripenem has a relatively low potential to induce seizures. The only known clinically relevant drug interaction is that coadministration with valproic acid may result in reductions of valproic acid serum concentrations. As with most renally eliminated antibiotics, the dose of doripenem should be adjusted according to kidney function.

CONCLUSION

Doripenem is an injectable carbapenem antibiotic with a spectrum of activity comparable to that of imipenem and meropenem. Its safety is similar to that of other carbapenems.

Doripenem versus bacteria: an emerging battleground

Doripenem is a new 1-beta-methyl carbapenem with broad-spectrum activity against clinically important pathogens. Its activity matches imipenem or ertapenem against Gram-positive bacteria and meropenem against Gram-negative bacteria. It may offer slightly more activity than meropenem against selected pathogens. It does not require the addition of cilastatin. Doripenem is stable to hydrolysis by most of the beta-lactamases, excluding carbapenem-hydrolyzing beta-lactamases. We performed dockings of imipenem, meropenem, ertapenem and doripenem with imipenem-hydrolyzing beta-lactamase, Sme1, separately. Energy calculations revealed that the complex involving doripenem was much less stable. Hence doripenem resists attack by carbapenem-hydrolyzing beta-lactamases at least to some extent. Empiric therapy with doripenem may be useful in hospital settings where multidrug resistance has emerged. However, the proper place for this drug in current antibiotic prescribing practices needs to be determined.

Characteristics of doripenem: a new broad-spectrum antibiotic

Doripenem (S-4661) is a new parenteral antibiotic from the carbapenem class; similarly to imipenem and meropenem, it has a broad-spectrum activity against Gram-positive, Gram-negative, and anaerobic bacteria. It is active against multiresistant Gram-negative bacilli such as extended-spectrum beta-lactamase-producing (ESBL) Gram-negative Enterobacteriaceae and nonfermentative Gram-negative bacilli including some strains of Pseudomonas aeruginosa that are resistant to other carbapenems. Doripenem’s chemical structure is similar to that of meropenem (substitution of one sulfamoxil-aminomethyl chain for the dimethyl-carboxyl chain), and has one 1-beta-methyl chain which provides resistance to dehydropeptidase-I enzyme. The clinical trials conducted so far have focused on the treatment of severe infections such as complicated intra-abdominal infections, complicated urinary tract infections and pyelonephritis, nosocomial pneumonia, and ventilator-associated pneumonia. Given its activity profile and the results from the clinical trials, this antibiotic may be used for empirical treatment of multibacterial infections produced by potentially multiresistant Gram-negative bacilli. In 2007, the US Food and Drug Administration approved the use of doripenem for the treatment of complicated intra-abdominal infections and complicated urinary tract infections. The European Medicines Agency has approved the use of doripenem for the same indications in addition to nosocomial pneumonia regardless of whether it is ventilator-associated or not.

An update on uncomplicated urinary tract infections in women

PURPOSE OF REVIEW

Urinary tract infections (UTIs) in women comprise uncomplicated and complicated UTIs. Uncomplicated UTIs, such as acute uncomplicated cystitis and pyelonephritis, are very common infections in otherwise healthy women, with a high tendency to recur. Although severe complications are rare, their high prevalence causes remarkable costs in the healthcare systems.

RECENT FINDINGS

As most scientific evidence has been gathered in uncomplicated UTI, this study focuses on recent developments in epidemiology, pathogenesis, cause, diagnosis, treatment and prevention of uncomplicated UTI and recurrent UTI in women.

SUMMARY

A remarkable increase of antibiotic resistance is also noted in uncomplicated UTI. Therefore, prudent use of antibiotic substances in uncomplicated UTI is increasingly important.