In vitro activity of linezolid against Gram-positive uropathogens of hospitalized patients with complicated urinary tract infections

Differences in Virulence Factors and Antimicrobial Susceptibility of Uropathogenic Enterococcus spp. Strains in a Rural Area of Uganda and a Spanish Secondary Hospital

Enterococcus faecalis and Enterococcus faecium have become two of the most important agents of nosocomial diseases due to their constantly growing resistance. Enterococcal infections are associated with biofilms, which are intrinsically sensitive to antimicrobials. The main goal of this study was to compare and relate their capacity to form biofilm and their antimicrobial sensitivity, as well as their virulence factors and their implicated genes, of strains isolated from patients with urinary tract infection (UTI) in a rural hospital in Uganda and a secondary hospital in Spain. A prospective study was conducted with 104 strains of E. faecalis and E. faecium isolated from patients with suspected UTI and who presented leukocyturia at the Saint Joseph Kitgum hospital (Uganda) and at the Hospital Universitario Principe de Asturias (Spain). All microorganisms were identified in Spain by MALDI-TOF mass spectrometry. Antimicrobial susceptibility studies were carried out using the Vitek^® 2 system (Biomériux, France). The biofilm formation capacity was studied by photospectrometry. Phenotypic and genotypic virulence factors were studied in all cases by PCR or expression techniques. In Uganda, we found a higher incidence of E. faecium (65.3%, n = 32), contrary to the situation found in Spain where most of the bacteria found belonged to E. faecalis (92.7%, n = 51). All E. faecalis strains were found to have very low levels of resistance to ampicillin, imipenem, and nitrofurantoin. However, E. faecium exhibited more than 25% resistance to these antibiotics. Although the esp gene has been shown in the results obtained to be an important initial agent in biofilm formation, we have also demonstrated in this study the intervention of other genes when esp is not present, such as the ace1 gene. No statistically significant relationships were found between the presence of agg and gelE genes and increased biofilm formation. The significant difference between the incidence of E. faecalis and E. faecium and biofilm formation, between samples from Spain and Uganda, shows us very different profiles between countries.

Safety considerations with new antibacterial approaches for chronic bacterial prostatitis

Introduction: Chronic bacterial prostatitis (CBP) is a difficult-to-eradicate infection. Antibacterial therapy with currently licensed agents is hindered due to the increasing emergence of pathogen resistance worldwide and to frequent infection relapse. With limited treatment options, physicians are investigating new agents, which, however, may raise safety concerns.Areas covered: Antibacterial agents currently licensed for CBP were not considered. Available reports about the safety and efficacy of antibacterial agents that have been clinically tested or tentatively used to treat CBP in single cases were evaluated. This review also focused on agents targeting Gram-positive pathogens, whose prevalence as causative agents of CBP is increasing.Expert opinion: (i) Most antibacterial agents considered in this review have been administered off-label in the interest of patients, and their use requires particular caution. (ii) Reports describing the usage of many of the drugs reviewed here are still scant, and readers should be warned of the limited published evidence supporting therapy for CBP with these agents. (iii) As treatment must extend over several weeks, medium-term adverse events may occur and therapy should be individualized, taking into account the dosage and the potential toxicity of each specific antibiotic. Regarding dangerous drug-drug interactions, particular attention should be paid to the risk of ECG-QT-interval elongation.

Therapeutic Dose Monitoring for Linezolid in a Patient with MRSA Pneumonia with Bacteremia in Diabetes Insipidus

INTRODUCTION

Few studies have investigated the effect of increased creatinine clearance (CrCl) on linezolid (LZD) concentration. Herein, we report the pharmacokinetic/pharmacodynamic (PK/PD) profile of LZD used in the management of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia with concomitant bacteremia in a patient with high CrCl caused by diabetes insipidus (DI).

CASE REPORT

A 19-year-old man was admitted to the intensive care unit following a traumatic brain injury. After admission, he underwent a craniotomy for the severe brain injury. However, he developed DI after the operation. Despite treatment with vasopressin, his urine output reached 5-6 L/day as a result of the DI, and his CrCl increased to 180-278 mL/min. We were required to administer 6-7 L of fluid a day to compensate for the high urinary fluid output. On day 55, MRSA pneumonia with sepsis was suspected and, consequently, LZD was administrated intravenously (600 mg every 12 h). He was treated with LZD for 14 days. The patient has since successfully recovered from MRSA pneumonia with concomitant bacteremia, and was transferred to the general ward on day 82. Blood LZD levels from days 60-68, which were measured after the patient's transfer to the general ward, showed that the trough levels were lower than the threshold level of detection. The blood 24-h area under the plasma LZD concentration-time curve (AUC)24/minimum inhibitory concentration (MIC) was 69.3.

CONCLUSION

In spite of the low level of LZD AUC24/MIC caused by the high CrCl with DI, MRSA pneumonia with concomitant bacteremia was successfully treated with LZD.

Current updates on oxazolidinone and its significance

Oxazolidinone is a five-member heterocyclic ring exhibiting potential medicinal properties with preferential antibacterial activity. Scientists reported various synthetic procedures for this heterocyclic structure. Current review articles tried to cover each and every potential aspect of oxazolidinone like synthetic routes, pharmacological mechanism of action, medicinal properties, and current research activities.

Hollow porous implants filled with mesoporous silica particles as a two-stage antibiotic-eluting device

A new type of implantable drug eluting device is presented, consisting of a bed of mesoporous microparticles packed inside a reservoir with a porous wall. This provides two sets of variables for drug release control that can be tailored independently. The first is related to the microparticles (packing density, size and pore structure) and the second to the reservoir (pore diameter and thickness of the wall, permeation area). In this work the concept is developed into a working model, used to fight bacterial (Staphylococcus aureus) growth by releasing linezolid that had previously been adsorbed on silica microparticles. These particles were placed inside the hollow interior of a porous medical grade stainless steel pin mimicking those used in traumatology and in orthopedic surgery. The mechanical behavior of the porous drug-eluting pin was tested and found satisfactory.

Discovery of a potent phenolic N1-benzylidene–pyridinecarboxamidrazone selective against Gram-positive bacteria

As part of a study into antimycobacterial compounds a set of phenolic N1-benzylidene-pyridinecarboxamidrazones was prepared and evaluated. This report describes the unexpected discovery of a potent compound with a pronounced selectivity for Gram-positive bacteria over Gram-negative micro-organisms. In addition, this compound is active against various drug-resistant Gram-positive bacteria.

New drugs for Gram-positive uropathogens

Complicated urinary tract infections (UTIs) are frequent nosocomial infections. The bacterial spectrum encompasses Gram-negative but also Gram-positive pathogens in up to 30-40%. The existing treatment for Gram-positive pathogens is not always optimal. Antimicrobials for the treatment of Gram-positive uropathogens comprise older agents, such as aminopenicillins with or without beta-lactamase inhibitors and vancomycin, as well as newer fluoroquinolones, such as levofloxacin or gatifloxacin. However, resistant bacteria such as vancomycin-resistant enterococci (VRE) or methicillin-resistant Staphylococcus aureus (MRSA) (except vancomycin-resistant) are generally also not susceptible to the fluoroquinolones. Therefore new agents need to be assessed in the treatment of UTI. Daptomycin and linezolid are new antimicrobial agents with good efficacy against Gram-positive uropathogens as shown by their minimal inhibitory concentrations. In a phase II study the urinary bactericidal activity of linezolid versus ciprofloxacin in volunteers showed comparable activity of both drugs against fluoroquinolone susceptible Gram-positive uropathogens, whereas linezolid was also as active against fluoroquinolone resistant ones. The pharmacokinetics and the mode of action of these two antibiotics are discussed together with some clinical data in the context of therapeutic use in patients with complicated UTIs.