The expanding role of fluoroquinolones

Ceragenin CSA-13 displays high antibacterial efficiency in a mouse model of urinary tract infection

Ceragenins (CSAs) are synthetic, lipid-based molecules that display activities of natural antimicrobial peptides. Previous studies demonstrated their high in vitro activity against pathogens causing urinary tract infections (UTIs), but their efficiency in vivo was not explored to date. In this study, we aimed to investigate the bactericidal efficiency of ceragenins against E. coli (Xen14 and clinical UPEC strains) isolates both in vitro and in vivo, as well to explore CSA-13 biodistribution and ability to modulate nanomechanical alterations of infected tissues using animal model of UTI. CSA-44, CSA-131 and particularly CSA-13 displayed potent bactericidal effect against tested E. coli strains, and this effect was mediated by induction of oxidative stress. Biodistribution studies indicated that CSA-13 accumulates in kidneys and liver and is eliminated with urine and bile acid. We also observed that ceragenin CSA-13 reverses infection-induced alterations in mechanical properties of mouse bladders tissue, which confirms the preventive role of CSA-13 against bacteria-induced tissue damage and potentially promote the restoration of microenvironment with biophysical features unfavorable for bacterial growth and spreading. These data justify the further work on employment of CSA-13 in the treatment of urinary tract infections.

Repeated exposure of nosocomial pathogens to silver does not select for silver resistance but does impact ciprofloxacin susceptibility

The rise of antimicrobial resistant bacteria coupled with a void in antibiotic development marks Antimicrobial Resistance as one of the biggest current threats to modern medicine. Antimicrobial metals are being developed and used as alternative anti-infectives, however, the existence of known resistance mechanisms and limited data regarding bacterial responses to long-term metal exposure are barriers to widespread implementation. In this study, a panel of reference and clinical strains of major nosocomial pathogens were subjected to serial dosage cycles of silver and ciprofloxacin. Populations exposed to silver initially showed no change in sensitivity, however, increasingly susceptibility was observed after the 25th cycle. A control experiment with ciprofloxacin revealed a selection for resistance over time, with silver treated bacteria showing faster adaptation. Morphological analysis revealed filamentation in Gram negative species suggesting membrane perturbation, while sequencing of isolated strains identified mutations in numerous genes. These included those encoding for efflux systems, chemosensory systems, stress responses, biofilm formation and respiratory chain processes, although no consistent locus was identified that correlated with silver sensitivity. These results suggest that de novo silver resistance is hard to select in a range of nosocomial pathogens, although silver exposure may detrimentally impact sensitivity to antibiotics in the long term. STATEMENT OF SIGNIFICANCE: The adaptability of microbial life continuously calls for the development of novel antibiotic molecules, however, the cost and risk associated with their discovery have led to a drying up in the pipeline, causing antimicrobial resistance (AMR) to be a major threat to healthcare. From all available strategies, antimicrobial metals and, more specifically, silver showcase large bactericidal spectrum and limited toxic effect which coupled with a large range of processes available for their delivery made these materials as a clear candidate to tackle AMR. Previous reports have shown the ability of this metal to enact a synergistic effect with other antimicrobial therapies, nevertheless, the discovery of Ag resistance mechanisms since the early 70s and limited knowledge on the long term influence of silver on AMR poses a threat to their applicability. The present study provides quantitative data on the influence of silver based therapies on AMR development for a panel of reference and clinical strains of major nosocomial pathogens, revealing that prolonged silver exposure may detrimentally impact sensitivity to antibiotics.

Marine Bacterial Esterases: Emerging Biocatalysts for Industrial Applications

The marine ecosystem has been known to be a significant source of novel enzymes. Esterase enzymes (EC 3.1.1.1) represent a diverse group of hydrolases that catalyze the cleavage and formation of ester bonds. Although esterases are widely distributed among marine organisms, only microbial esterases are of paramount industrial importance. This article discusses the importance of marine microbial esterases, their biochemical and kinetic properties, and their stability under extreme conditions. Since culture-dependent techniques provide limited insights into microbial diversity of the marine ecosystem, therefore, genomics and metagenomics approaches have widely been adopted in search of novel esterases. Additionally, the article also explains industrial applications of marine bacterial esterases particularly for the synthesis of optically pure substances, the preparation of enantiomerically pure drugs, the degradation of human-made plastics and organophosphorus compounds, degradation of the lipophilic components of the ink, and production of short-chain flavor esters.

Water pollution and observation of acquired antibiotic resistance in Bayou Lafourche, a major drinking water source in Southeast Louisiana, USA

Antibiotics are known to enter the environment, not only by human excretion but also through livestock/aquaculture, healthcare facilities, and pharmaceutical industry waste. Once in the environment, antibiotics have the ability to provide a selective pressure in microbial communities thus selecting for resistance. Bayou Lafourche of Southeastern Louisiana serves as the raw source of drinking water for 300,000 people in the region and has previously been shown to receive high amounts of fecal contamination. Four sites along the bayou and one site from its input source on the Mississippi River were monitored for water chemistry, total and fecal coliform estimates, and presence of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARG) for a period of 1 year. Four waste-associated bacterial isolates were tested for resistance to antibiotics (tetracycline, sulfamethoxazole/trimethoprim, cefoxitin, meropenem, imipenem, erythromycin, and vancomycin). Resistant bacteria were further examined with PCR/electrophoresis to confirm the presence of antibiotic resistance genes (Sul1, tet(A), tet(W), tet(X), IMP, KPC, and OXA-48). The bayou appears to meet the Louisiana Department of Environmental Quality (LDEQ) criteria for water chemistry, yet fecal coliforms were consistently higher than LDEQ thresholds, thus indicating fecal contamination. Enterobacteriaceae isolates showed 13.6%, 10.9%, and 19.8% resistant to tetracycline, sulfamethoxazole/trimethoprim, and cefoxitin, respectively, and 11 isolates were confirmed for presence of either tet(A) or Sul1 resistance genes. High fecal coliforms and presence of ARB/ARG may both indicate a presence of anthropogenic or agricultural source of fecal contamination.

Incidence, Risk Factors, and Impact of Clostridium difficile Colitis Following Primary Total Hip and Knee Arthroplasty

BACKGROUND

An improved understanding of Clostridium difficile is important as it is used as a measure of hospital quality and is associated with substantial morbidity. This study utilizes the National Surgical Quality Improvement Program to determine the incidence, timing, risk factors, and clinical implications of C difficile colitis in patients undergoing primary total hip or knee arthroplasty (THA or TKA).

METHODS

Patients who underwent primary THA or TKA as part of the 2015 National Surgical Quality Improvement Program were identified. The primary outcome was a diagnosis of C difficile colitis within the 30-day postoperative period. Risk factors for the development of C difficile colitis were identified using Poisson multivariate regression.

RESULTS

A total of 39,172 patients who underwent primary THA or TKA were identified. The incidence of C difficile colitis was 0.10% (95% confidence interval [CI] 0.07-0.13). Of the cases that developed C difficile colitis, 79% were diagnosed after discharge and 84% had not had a preceding infection diagnosed. Independent preoperative and procedural risk factors for the development of C difficile colitis were greater age (most notably ≥80 years old, relative risk [RR] 5.28, 95% CI 1.65-16.92, P = .008), dependent functional status (RR 4.05, 95% CI 1.44-11.36, P = .008), preoperative anemia (RR 2.52, 95% CI 1.28-4.97, P = .007), hypertension (RR 2.51, 95% CI 1.06-5.98, P = .037), and THA (vs TKA; RR 2.25, 95% CI 1.16-4.36, P = .017). Postoperative infectious risk factors were urinary tract infection (RR 10.66, 95% CI 3.77-30.12, P < .001), sepsis (RR 17.80, 95% CI 3.77-84.00, P < .001), and "any infection" (RR 6.60, 95% CI 2.66-16.34, P < .001).

CONCLUSION

High-risk patients identified in this study should be targeted with preventative interventions and have perioperative antibiotics judiciously managed.

Rational design strategies for FimH antagonists: new drugs on the horizon for urinary tract infection and Crohn's disease

INTRODUCTION

The bacterial adhesin FimH is a virulence factor and an attractive therapeutic target for urinary tract infection (UTI) and Crohn's Disease (CD). Located on type 1 pili of uropathogenic E. coli (UPEC), the FimH adhesin plays an integral role in the pathogenesis of UPEC. Recent efforts have culminated in the development of small-molecule mannoside FimH antagonists that target the mannose-binding lectin domain of FimH, inhibiting its function and preventing UPEC from binding mannosylated host cells in the bladder, thereby circumventing infection. Areas covered: The authors describe the structure-guided design of mannoside ligands, and review the structural biology of the FimH lectin domain. Additionally, they discuss the lead optimization of mannosides for therapeutic application in UTI and CD, and describe various assays used to measure mannoside potency in vitro and mouse models used to determine efficacy in vivo. Expert opinion: To date, mannoside optimization has led to a diverse set of small-molecule FimH antagonists with oral bioavailability. With clinical trials already initiated in CD and on the horizon for UTI, it is the authors, opinion that mannosides will be a 'first-in-class' treatment strategy for UTI and CD, and will pave the way for treatment of other Gram-negative bacterial infections.

Quality of life and changes in symptom relief in patients with acute uncomplicated cystitis treated with antibiotics: a prospective, open-label, multicenter, observational study

The purpose of this study was to investigate the effect of ciprofloxacin treatment on quality of life and symptom improvement in patients with simple cystitis. Between January 2010 and December 2010, ciprofloxacin was administered twice daily for 5 days, and changes in the patients' symptoms, the therapeutic effects, and changes in the Korean version of the Urinary Tract Infection Symptoms Assessment (UTISA) score were evaluated. Patients were classified into two groups according to the self-reported degree of symptom improvement. Significant improvement was noted in symptoms such as frequency, urgency, dysuria, tenesmus, lower abdominal discomfort, back pain, and gross hematuria. The treatment success group comprised 249 patients and the treatment failure group comprised 45 patients. Baseline frequency and urgency, tenesmus, and lower abdominal discomfort were worse in the treatment failure group, although the difference was significant only for frequency (p = 0.029) and urgency (p = 0.028). All UTISA subcategory scores showed improvement in the treatment success group, and the median time to symptom improvement was 2.40 days. In the treatment failure group, some UTISA subcategory scores showed significant improvement, including those for dysuria (1.67 to 0.89), tenesmus (1.76 to 1.08), and gross hematuria (0.80 to 0.21), although significant improvement in frequency, urgency, lower abdominal discomfort, and back pain was not observed. The UTISA questionnaire was useful in reflecting the severity of simple cystitis symptoms. Frequency, urgency, lower abdominal discomfort, and back pain were not adequately improved in the treatment failure group, with frequency and urgency being predisposing factors for treatment failure.

Antimicrobial Susceptibility Patterns of Contemporary Pathogens from Uncomplicated Urinary Tract Infections Isolated in a Multicenter Italian Survey: Possible Impact on Guidelines

During 2004 four Italian Laboratories assessed the prevalence of antimicrobial resistance among uropathogens causing acute uncomplicated cystitis in female out-patients. A total of 600 urine samples from individuals aged 18-65 were studied. The overall prevalence of Escherichia coli was 85.3%. Klebsiella pneumoniae, Staphylococcus saprophyticus, Proteus mirabilis, Enterococcus faecalis and other rarer species were far less represented. Determination of the antibiotic susceptibility pattern of the entire collection of E. coli (512 organisms) revealed that among the drugs analyzed ampicillin was the least active molecule with only 62.5% of the strains being inhibited. Amoxicillin-clavulanate and cefuroxime displayed a higher potency (87.7% and 89.2% respectively). Cotrimoxazole inhibited only 70.1% of the uropathogens. The three fluoquinolones tested had comparable activity ranging from 83.0% for ciprofloxacin, to 83.6% for levofloxacin and 84.9% for prulifloxacin, indicating an identical spectrum of cross resistance. Nitrofurantoin (96.7%) and fosfomycin (98.6%) were the most potent drugs. Against the whole collection of uropathogens, only cefuroxime, nitrofurantoin and fosfomycin overcame the threshold of 90% activity, with the fluoroquinolones and amoxicillin-clavulanate suffering from about 15% resistance. The results of this survey strongly support the conclusions of recent Italian guidelines concerning the best empiric treatment of UTI in this country today.

Treatment and prevention of urinary tract infection with orally active FimH inhibitors

Chronic and recurrent urinary tract infections pose a serious medical problem because there are few effective treatment options. Patients with chronic urinary tract infections are commonly treated with long-term prophylactic antibiotics that promote the development of antibiotic-resistant forms of uropathogenic Escherichia coli (UPEC), further complicating treatment. We developed small-molecular weight compounds termed mannosides that specifically inhibit the FimH type 1 pilus lectin of UPEC, which mediates bacterial colonization, invasion, and formation of recalcitrant intracellular bacterial communities in the bladder epithelium. Here, we optimized these compounds for oral bioavailability and demonstrated their fast-acting efficacy in treating chronic urinary tract infections in a preclinical murine model. These compounds also prevented infection in vivo when given prophylactically and strongly potentiated the activity of the current standard of care therapy, trimethoprim-sulfamethoxazole, against clinically resistant PBC-1 UPEC bacteria. These compounds have therapeutic efficacy after oral administration for the treatment of established urinary tract infections in vivo. Their unique mechanism of action-targeting the pilus tip adhesin FimH-circumvents the conventional requirement for drug penetration of the outer membrane, minimizing the potential for the development of resistance. The small-molecular weight compounds described herein promise to provide substantial benefit to women suffering from chronic and recurrent urinary tract infections.

14-day prulifloxacin treatment of acute uncomplicated cystitis in women with recurrent urinary tract infections: a prospective, open-label, pilot trial with 6-month follow-up

Recurrent urinary tract infections (UTI) are very common in otherwise healthy young women, and can have a very negative social and economic impact. In order to evaluate the tolerability and efficacy of a 14-day course of prulifloxacin orally administered once daily, 51 young female patients, attending the same STD center between may and June 2007 for symptoms of cystitis, with a history of recurrent UTI and urine culture positive for uropathogens, were enrolled in this prospective study. Microbiological and clinical efficacy was tested over three follow-up visits at 1, 3 and 6 months. Quality of life (QoL) was measured and the impact of prulifloxacin in modifying the Lactobacillus vaginal flora was also evaluated. At baseline, the pathogens most commonly isolated were Enterococcus faecalis (43.2%) and Escherichia coli (27.5%). 41 of the 51 women, (80.3%) had Lactobacillus spp. in vaginal samples at baseline. microbiological results at follow-up examinations were as follows: after 1 month, 47 patients were recurrence-free and 4 had recurrence; after 3 months, 41 were recurrence-free, while 6 reported recurrence; finally, after 6 months, 36 were recurrence-free and 5 had recurrence. A statistically significant difference was reported between the QoL questionnaire mean scores at baseline (0.63), 1 (0.77), 3 (0.77) and 6 months (0.78) after treatment (all p<0.001). the vaginal swab cultures demonstrated that Lactobacillus spp. flora was maintained in 38 out of the 41 (92.6%) patients who had positive vaginal swab sample at baseline. in conclusion, a 14-day administration of prulifloxacin 600 mg is a safe, well tolerated and effective treatment for the management of UTI in young women.

Early switch to oral versus intravenous antimicrobial treatment for hospitalized patients with acute pyelonephritis: a systematic review of randomized controlled trials

BACKGROUND

Acute pyelonephritis is a common infection with significant morbidity and mortality, particularly in pediatric populations. Early-switch strategies (from intravenous to oral treatment) may be an acceptable or even preferred option in the treatment of patients with acute pyelonephritis in terms of effectiveness and safety and can also reduce the economical burden associated with pyelonephritis.

OBJECTIVE

We sought to evaluate the effectiveness and safety of early-switch strategies in hospitalized patients with acute uncomplicated pyelonephritis.

METHODS

We searched in PubMed, Cochrane Central Register of Controlled Trials, and Scopus to identify randomized controlled trials (RCTs) that compared intravenous antibiotic regimens to regimens including an early switch to oral (after initial intravenous) treatment.

RESULTS

Eight RCTs (6 in children) were eligible for inclusion. In 5 RCTs the intravenous antibiotic treatment arms were not switched to oral treatment until the end of the study while in the remaining 3 RCTs the intravenous arms were switched late to oral treatment (after 5-10 days). Data regarding the incidence of renal scars, microbiological eradication, clinical cure, reinfection, persistence of acute pyelonephritis, and adverse events were provided in 4 (all pediatric trials), 6 (4 pediatric), 4 (2 pediatric), 5 (3 pediatric), 3 (1 pediatric), and 5 RCTs (3 pediatric), respectively. There were no differences regarding the above outcomes between the two compared treatment regimens in either pediatric or adult populations.

CONCLUSION

Early switch to oral antibiotic strategies seem to be as effective and safe as intravenous regimens for the treatment of hospitalized patients with acute pyelonephritis. These findings suggest that there is probably a potential to decrease the duration of intravenous treatment by 4-11 days in hospitalized patients with acute pyelonephritis without compromising their outcomes.

Emerging drugs for bacterial urinary tract infections

Bacterial urinary tract infections (UTIs) are frequent infections in the outpatient as well as in the nosocomial setting. The stratification into uncomplicated and complicated UTIs has proven to be clinically useful. Bacterial virulence factors on the one side and the integrity of the host defence mechanisms on the other side determine the course of the infection. In uncomplicated UTIs, Escherichia coli is the leading organism, whereas in complicated UTIs, the bacterial spectrum is much broader, including Gram-negative, Gram-positive and often multiresistant organisms. The therapy of uncomplicated UTIs is almost exclusively antibacterial, whereas in complicated UTIs the complicating factors also have to be treated. There are two predominant aims in the antimicrobial treatment of both uncomplicated and complicated UTIs: i) rapid and effective response to therapy and prevention of recurrence of the individual patient treated; and ii) prevention of emergence of resistance to chemotherapy in the microbial environment. The aim of this review is to highlight the existing, and to describe emerging, treatment options for UTIs.