Pharmacokinetic considerations regarding tigecycline for multidrug-resistant (MDR) Klebsiella pneumoniae or MDR Acinetobacter baumannii urosepsis

Current and Emerging Treatment Options for Multidrug Resistant Escherichia coli Urosepsis: A Review

Escherichia coli is a versatile commensal and pathogenic member of the human microflora. As the primary causative pathogen in urosepsis, E. coli places an immense burden on healthcare systems worldwide. To further exacerbate the issue, multi drug resistance (MDR) has spread rapidly through E. coli populations, making infections more troublesome and costlier to treat. This paper aimed to review the literature concerning the development of MDR in uropathogenic E. coli (UPEC) and explore the existing evidence of current and emerging treatment strategies. While some MDR strains maybe treated with β-lactam-β-lactamase inhibitor combinations as well as cephalosporins, cephamycin, temocillin and fosfomycin, current treatment strategies for many MDR UPEC strains are reliant on carbapenems. Carbapenem overreliance may contribute to the alarming dissemination of carbapenem-resistance amongst some UPEC communities, which has ushered in a new age of difficult to treat infections. Alternative treatment options for carbapenem resistant UPEC may include novel β-lactam-β-lactamase or carbapenemase inhibitor combinations, cefiderocol, polymyxins, tigecycline, aminoglycosides or fosfomycin. For metallo-β-lactamase producing strains (e.g., NDM, IMP-4), combinations of cefazidime-avibacam with aztreonam have been used. Additionally, the emergence of new antimicrobials brings new hope to the treatment of such infections. However, continued research is required to successfully bring these into the clinic for the treatment of MDR E. coli urosepsis.

Clinical study on the safety and efficacy of high-dose tigecycline in the elderly patients with multidrug-resistant bacterial infections: A retrospective analysis

Multidrug-resistant bacterial (MDRB) infections have been difficult to treat clinically. Tigecycline (TIG) has several advantages, especially in the treatment of severe infections. Many clinicians have considered increasing the TIG dose to improve the efficacy of this molecule. The safety and efficacy of high-dose TIG in elderly patients with MDRB infections were investigated in this study.We conducted a retrospective analysis of the elderly patients with MDRB infections who were treated at the First Affiliated Hospital. A total of 106 patients received a conventional dose (CD-TIG group: 50 mg every 12 hours) of TIG and 51 received a high dose (HD-TIG group: 100 mg every 12 hours). The data from all patients were collected for examining the clinical features and performing the microbiological analysis. The safety profile and efficacy of the HD regimen were investigated.The clinical efficacy and microbiological eradication in the patients with MDRB infection were higher in the HD-TIG group than the CD-TIG group. The independent predictors of clinical cure were the use of TIG at HD (odd ratio [OR], 5.129; 95% confidence interval [CI] [1.890, 13.921]; P = .001) and microbiological eradication (OR, 3.049; 95% CI, [1.251, 7.430]; P = .014). In the ventilator-associated pneumonia (VAP) and bloodstream infection (BSI) subgroups, the sole independent predictor of clinical cure was the HD of TIG, and no significant adverse events were observed. The occurrence of multidrug-resistant Acinetobacter baumannii infection and an MIC value of 1 to 2 g/mL for TIG were independently associated with clinical failure in the VAP subgroup.HDs of TIG was found to associate with better clinical efficacy and microbiological eradication than its CDs in the elderly patients with MDRB infections. In the VAP and BSIs subgroups, administration of HDs of TIG was associated with better outcomes.

Adverse events of high-dose tigecycline in the treatment of ventilator-associated pneumonia due to multidrug-resistant pathogens

The off-label uses of tigecycline (TGC) to treat ventilator-associated pneumonia (VAP) have aroused worldwide concerns. The efficacy about TGC has been recently reported. However, the adverse events (AEs) remain controversial. Our study aims to analyze the safety of the high-dose (HD) regimens in the treatment of VAP due to multidrug-resistant (MDR) pathogens.The clinical data of 134 patients who were diagnosed with VAP from January 2013 to December 2015 in the NeuroScience Care Unit (NCU) were analyzed retrospectively. The incidence and the occurrence time of AEs, 28-day mortality, and the factors of clinical effectiveness were explored.A total of 54 patients received the standard dose group (SD), 69 in the HD, and 11 in the nonstandard HD group (NHD). Acinetobacter baumannii were the main pathogenic bacteria. There was no statistic difference in the incidence of AEs and the 28-day mortality among the 3 groups (P > .05). Total bilirubin (TBIL) increased significantly after SD of TGC treatment (P = .004). Liver dysfunction occurred the latest (10.83 ± 7.08), not in the duration of HD group (9.63 ± 3.92), whereas in the SD group (13.00 ± 7.57) and NHD group (12.64 ± 3.70). Patients with septic shock, MODS, and higher APACHE II score were of high risk in mortality. The HD group was associated with higher clinical effective rate and bacteria clearance rate.HD TGC was relatively safe and tolerable in ICU patients. The risk of side effects was related to the TGC duration, although not increased as the dosage rose. Full course of the HD regimen was associated with better outcomes for the treatment of VAP patients, especially for the MDR gram-negative bacilli infection. Inappropriate antimicrobial treatment might lead to clinical treatment failure.

Antibiotic Stewardship: Strategies to Minimize Antibiotic Resistance While Maximizing Antibiotic Effectiveness

Empiric therapy of the septic patient in the hospital is challenging. Antibiotic stewardship is concerned with optimizing antibiotic use and minimizing resistance. Clinicians should avoid overcovering and overtreating colonizing organisms in respiratory secretions and urinary catheters. Empiric therapy should take into account the prevalence of multidrug-resistant organisms in the hospital setting. The most effective resistance prevention strategies is to preferentially select a low resistance potential antibiotic, which should be administered in the highest possible dose without toxicity for the shortest duration to eliminate the infection.

Pharmacokinetic/pharmacodynamic parameters for treatment optimization of infection due to antibiotic resistant bacteria: a summary for practical purposes in children and adults

In the last years, there has been a tremendous increase in the incidence of bacterial infections due to resistant strains, especially multi-drug resistant Gram-negative bacilli. In Europe, a north to south and a west to east gradient was noticed, with more than one third of the K. pneumonia isolates being resistant to carbapenems in few countries. New antibiotics are lacking and, as a consequence, pharmacokinetic/pharmacodynamic parameters, normalized to pathogen minimal inhibitory concentration, are used with increased frequency to treat infections due to difficult-to-treat pathogens. These parameters are available at least for the adult population, but sparse in many different publications. This review wants to provide a comprehensive and 'easy to read' text for everyday practice, briefly summarizing the presently available knowledge on pharmacokinetic/pharmacodynamic parameters (normalized for minimal inhibitory concentration values) of different class drugs, that can be applied for an effective antibacterial treatment infections due to antibiotic-resistant pathogens.

Acinetobacter Prosthetic Joint Infection Treated with Debridement and High-Dose Tigecycline

Prosthesis retention is not recommended for multidrug-resistant Acinetobacter prosthetic joint infection due to its high failure rate. Nevertheless, replacing the prosthesis implies high morbidity and prolonged hospitalization. Although tigecycline is not approved for the treatment of prosthetic joint infection due to multidrug resistant Acinetobacter baumannii, its appropriate use may preclude prosthesis exchange. Since the area under the curve divided by the minimum inhibitory concentration is the best pharmacodynamic predictor of its efficacy, we used tigecycline at high dose, in order to optimize its efficacy and achieve implant retention in 3 patients who refused prosthesis exchange. All patients with prosthetic joint infections treated at our Institution are prospectively registered in a database. Three patients with early prosthetic joint infection of total hip arthroplasty due to multidrug resistant A. baumannii were treated with debridement, antibiotics and implant retention, using a high maintenance dose of tigecycline (100 mg every 12 hours). The cases were retrospectively reviewed. All patients signed informed consent for receiving off-label use of tigecycline.

Tigecycline was well tolerated, allowing its administration at high maintenance dose for a median of 40 days (range 30–60). Two patients were then switched to minocycline at standard doses for a median of 3.3 months in order to complete treatment. Currently, none of the patients showed relapse. Increasing the dose of tigecycline could be considered as a means to better attain pharmacodynamic targets in patients with severe or difficult-to-treat infections. Tigecycline at high maintenance dose might be useful when retention of the implant is attempted for treatment for prosthetic joint infections due to multidrug resistant Acinetobacter. Although this approach might be promising, off-label use of tigecycline should be interpreted cautiously until prospective data are available. Tigecycline is probably under-dosed for the treatment of implant and biofilm associated infections.

Minocycline and Tigecycline: What Is Their Role in the Treatment of Carbapenem-Resistant Gram-Negative Organisms?

Carbapenem-resistant organisms are increasingly common worldwide, particularly in India and are associated with high mortality rates especially in patients with severe infection such as bacteremia. Existing drugs such as carbapenems and polymyxins have a number of disadvantages, but remain the mainstay of treatment. The tetracycline class of antibiotics was first produced in the 1940s. Minocycline, tetracycline derivative, although licensed for treatment of wide range of infections, has not been considered for treatment of multidrug-resistant organisms until recently and needs further in vivo studies. Tigecycline, a derivative of minocycline, although with certain disadvantages, has been frequently used in the treatment of carbapenem-resistant organisms. In this article, we review the properties of minocycline and tigecycline, the common mechanisms of resistance, and assess their role in the management of carbapenem-resistant organisms.

Management of Infections with Drug-Resistant Organisms in Critical Care: An Ongoing Battle

Infections with multidrug-resistant organisms (MDROs) are common in critically ill patients and are challenging to manage appropriately. Strategies that can be used in the treatment of MDRO infections in the intensive care unit (ICU) include combination therapy, adjunctive aerosolized therapy, and optimization of pharmacokinetics with higher doses or extended-infusion therapy as appropriate. Rapid diagnostic tests could assist in improving timely appropriate antimicrobial therapy for MDRO infections in the ICU.

Treatment Options for Carbapenem-Resistant Enterobacteriaceae Infections

This article provides a comprehensive review of currently available treatment options for infections due to carbapenem-resistant Enterobacteriaceae (CRE). Antimicrobial resistance in Gram-negative bacteria is an emerging and serious global public health threat. Carbapenems have been used as the "last-line" treatment for infections caused by resistant Enterobacteriaceae, including those producing extended spectrum ß-lactamases. However, Enterobacteriaceae that produce carbapenemases, which are enzymes that deactivate carbapenems and most other ß-lactam antibiotics, have emerged and are increasingly being reported worldwide. Despite this increasing burden, the most optimal treatment for CRE infections is largely unknown. For the few remaining available treatment options, there are limited efficacy data to support their role in therapy. Nevertheless, current treatment options include the use of older agents, such as polymyxins, fosfomycin, and aminoglycosides, which have been rarely used due to efficacy and/or toxicity concerns. Optimization of dosing regimens and combination therapy are additional treatment strategies being explored. Carbapenem-resistant Enterobacteriaceae infections are associated with poor outcomes and high mortality. Continued research is critically needed to determine the most appropriate treatment.

Piscidin is highly active against carbapenem-resistant Acinetobacter baumannii and NDM-1-producing Klebsiella pneumonia in a systemic Septicaemia infection mouse model

This study was designed to investigate the antimicrobial activity of two synthetic antimicrobial peptides from an aquatic organism, tilapia piscidin 3 (TP3) and tilapia piscidin 4 (TP4), in vitro and in a murine sepsis model, as compared with ampicillin, tigecycline, and imipenem. Mice were infected with (NDM-1)-producing K. pneumonia and multi-drug resistant Acinetobacter baumannii, and subsequently treated with TP3, TP4, or antibiotics for different periods of time (up to 168 h). Mouse survival and bacterial colony forming units (CFU) in various organs were measured after each treatment. Toxicity was determined based on observation of behavior and measurement of biochemical parameters. TP3 and TP4 exhibited strong activity against K. pneumonia and A. baumannii in vitro. Administration of TP3 (150 μg/mouse) or TP4 (50 μg/mouse) 30 min after infection with K. pneumonia or A. baumannii significantly increased survival in mice. TP4 was more effective than tigecycline at reducing CFU counts in several organs. TP3 and TP4 were shown to be non-toxic, and did not affect mouse behavior. TP3 and TP4 are able at potentiate anti-Acinetobacter baumannii or anti-Klebsiella pneumonia drug activity, reduce bacterial load, and prevent drug resistance, indicating their potential for use in combating multidrug-resistant bacteria.

Global assessment of antimicrobial susceptibility among Gram-negative organisms collected from pediatric patients between 2004 and 2012: results from the Tigecycline Evaluation and Surveillance Trial

The Tigecycline Evaluation and Surveillance Trial (TEST) was designed to monitor susceptibility to commonly used antimicrobial agents among important pathogens. We report here on susceptibility among Gram-negative pathogens collected globally from pediatric patients between 2004 and 2012. Antimicrobial susceptibility was determined using guidelines published by the Clinical and Laboratory Standards Institute (CLSI). Most Enterobacteriaceae showed high rates of susceptibility (>95%) to amikacin, tigecycline, and the carbapenems (imipenem and meropenem); 90.8% of Acinetobacter baumannii isolates were susceptible to minocycline, and susceptibility rates were highest in North America, Europe, and Asia/Pacific Rim. Amikacin was the most active agent against Pseudomonas aeruginosa (90.4% susceptibility), with susceptibility rates being highest in North America. Extended-spectrum β-lactamases (ESBLs) were reported for 11.0% of Escherichia coli isolates and 24.2% of Klebsiella pneumoniae isolates globally, with rates reaching as high as 25.7% in the Middle East and >43% in Africa and Latin America, respectively. Statistically significant (P<0.01) differences in susceptibility rates were noted between pediatric age groups (1 to 5 years, 6 to 12 years, or 13 to 17 years of age), globally and in some regions, for all pathogens except Haemophilus influenzae. Significant (P<0.01) differences were reported for all pathogens globally and in most regions, considerably more frequently, when pediatric and adult susceptibility results were compared. Amikacin, tigecycline, and the carbapenems were active in vitro against most Gram-negative pathogens collected from pediatric patients; A. baumannii and P. aeruginosa were susceptible to fewer antimicrobial agents. Susceptibility rates among isolates from pediatric patients were frequently different from those among isolates collected from adults.

Treating infections caused by carbapenemase-producing Enterobacteriaceae

Carbapenemase-producing Enterobacteriaceae (CPE) have spread worldwide, causing serious infections with increasing frequency. CPE are resistant to almost all available antibiotics, complicating therapy and limiting treatment options. Mortality rates associated with CPE infections are unacceptably high, indicating that the current therapeutic approaches are inadequate and must be revised. Here, we review 20 clinical studies (including those describing the largest cohorts of CPE-infected patients) that provided the necessary information regarding isolate and patient characteristics and treatment schemes, as well as a clear assessment of outcome. The data summarized here indicate that treatment with a single in vitro active agent resulted in mortality rates not significantly different from that observed in patients treated with no active therapy, whereas combination therapy with two or more in vitro active agents was superior to monotherapy, providing a clear survival benefit (mortality rate, 27.4% vs. 38.7%; p <0.001). The lowest mortality rate (18.8%) was observed in patients treated with carbapenem-containing combinations.

Treatment for infections with carbapenem-resistant Enterobacteriaceae: what options do we still have?

The global spread of carbapenem-resistant Enterobacteriaceae (CRE) is increasingly becoming a major challenge in clinical and public health settings. To date, the treatment for serious CRE infections remains difficult. The intelligent use of antimicrobials and effective infection control strategies is crucial to prevent further CRE spread. Early consultation with experts in the treatment of infections with multidrug-resistant organisms is valuable in patient management. This brief review will focus on the current, yet limited, treatment options for CRE infections.

Tigecycline in treatment of multidrug-resistant Gram-negative bacillus urinary tract infections: a systematic review

OBJECTIVES

To review cases of multidrug-resistant (MDR) Gram-negative bacillus urinary tract infections (UTIs) treated with tigecycline and the literature related to this subject.

METHODS

We performed a systematic review of the literature identifying patients with MDR Gram-negative bacillus UTIs treated with tigecycline.

RESULTS

Fourteen cases describing treatment of UTIs caused by MDR Gram-negative bacilli with tigecycline are reviewed. Favourable clinical outcomes were noted in 11 of 14 cases. An initial favourable microbiological outcome was noted in 12 cases. Post-treatment cultures in two cases were positive for tigecycline-resistant organisms.

CONCLUSIONS

The clinical efficacy of tigecycline for treatment of UTIs has not been extensively evaluated. Based on the available literature, tigecycline appears to have efficacy in some patients with MDR Gram-negative bacillus UTIs. Further research in this area is needed to fully elucidate the role of tigecycline in treating such patients.

High dose tigecycline in critically ill patients with severe infections due to multidrug-resistant bacteria

INTRODUCTION

The high incidence of multidrug-resistant (MDR) bacteria among patients admitted to ICUs has determined an increase of tigecycline (TGC) use for the treatment of severe infections. Many concerns have been raised about the efficacy of this molecule and increased dosages have been proposed. Our purpose is to investigate TGC safety and efficacy at higher than standard doses.

METHODS

We conducted a retrospective study of prospectively collected data in the ICU of a teaching hospital in Rome. Data from all patients treated with TGC for a microbiologically confirmed infection were analyzed. The safety profile and efficacy of high dosing regimen use were investigated.

RESULTS

Over the study period, 54 patients (pts) received TGC at a standard dose (SD group: 50 mg every 12 hours) and 46 at a high dose (HD group: 100 mg every 12 hours). Carbapenem-resistant Acinetobacter.baumannii (blaOXA-58 and blaOXA-23 genes) and Klebsiella pneumoniae (blaKPC-3 gene) were the main isolated pathogens (n = 79). There were no patients requiring TGC discontinuation or dose reduction because of adverse events. In the ventilation-associated pneumonia population (VAP) subgroup (63 patients: 30 received SD and 33 HD), the only independent predictor of clinical cure was the use of high tigecycline dose (odds ratio (OR) 6.25; 95% confidence interval (CI) 1.59 to 24.57; P = 0.009) whilst initial inadequate antimicrobial treatment (IIAT) (OR 0.18; 95% CI 0.05 to 0.68; P = 0.01) and higher Sequential Organ Failure Assessment (SOFA) score (OR 0.66; 95% CI 0.51 to 0.87; P = 0.003) were independently associated with clinical failure.

CONCLUSIONS

TGC was well tolerated at a higher than standard dose in a cohort of critically ill patients with severe infections. In the VAP subgroup the high-dose regimen was associated with better outcomes than conventional administration due to Gram-negative MDR bacteria.

Colistin resistance in Klebsiella pneumoniae

Increasing use of colistin for multidrug-resistant Gram-negative bacterial infections has led to the emergence of colistin resistance in Klebsiella pneumoniae in several countries worldwide, including Europe (especially Greece), and colistin resistance rates are continually increasing. Heteroresistance rates, which were significantly higher than resistance rates, were found to be important. Although the mechanism underlying resistance is unclear, it has been suggested that it is related to lipopolysaccharide modification via diverse routes. Several factors have been reported as being associated with colistin resistance, with improper use and patient-to-patient transmission being most often cited. Total infections and infection-related mortality from colistin-resistant K. pneumoniae are high, but currently there are no established treatment regimens. However, several combination regimens that are mainly colistin-based have been found to be successful for treating such infections.

β-Lactamase production in key gram-negative pathogen isolates from the Arabian Peninsula

SUMMARY Infections due to Gram-negative bacilli (GNB) are a leading cause of morbidity and mortality worldwide. The extent of antibiotic resistance in GNB in countries of the Gulf Cooperation Council (GCC), namely, Saudi Arabia, United Arab Emirates, Kuwait, Qatar, Oman, and Bahrain, has not been previously reviewed. These countries share a high prevalence of extended-spectrum-β-lactamase (ESBL)- and carbapenemase-producing GNB, most of which are associated with nosocomial infections. Well-known and widespread β-lactamases genes (such as those for CTX-M-15, OXA-48, and NDM-1) have found their way into isolates from the GCC states. However, less common and unique enzymes have also been identified. These include PER-7, GES-11, and PME-1. Several potential risk factors unique to the GCC states may have contributed to the emergence and spread of β-lactamases, including the unnecessary use of antibiotics and the large population of migrant workers, particularly from the Indian subcontinent. It is clear that active surveillance of antimicrobial resistance in the GCC states is urgently needed to address regional interventions that can contain the antimicrobial resistance issue.

Tigecycline therapy for infections due to carbapenemase-producing Klebsiella pneumoniae in critically ill patients

BACKGROUND

The aim of this study was to assess the efficacy of tigecycline in the treatment of infections due to carbapenemase-producing Klebsiella pneumoniae (CPKP) in critically ill patients.

METHODS

A retrospective observational study was conducted in critically ill patients receiving different tigecycline doses for severe CPKP infections. We evaluated demographic data, localization and severity of infection, response to therapy, and mortality.

RESULTS

Fifteen patients received tigecycline for 16 episodes of CPKP infection. The main infections were pneumonia (31%), urinary tract infection (31%), peritonitis (20%), catheter-related bacteraemia (12%), and meningitis (6%). Most infections were complicated with severe sepsis (44%), septic shock (12%), and/or bacteraemia (19%). The daily maintenance dose of tigecycline was 200 mg in 10 episodes and 100 mg in 6 episodes. The overall 30-day mortality rate was 25%. Univariate analysis showed that mortality was significantly associated (p < 0.01) with mean APACHE II and SOFA scores and the presence of immunosuppression, but not with the tigecycline dose.

CONCLUSIONS

Tigecycline appears to be an effective therapy for severe infections due to CPKP in critically ill patients. Mortality is related to the severity of the underlying disease. We observed no benefit from a higher maintenance dose of tigecycline, although the number of patients included in the study was too small to draw any general conclusions in this regard.

Combination therapy for carbapenem-resistant Gram-negative bacteria

The emergence of resistant to carbapenems Gram-negative bacteria (CR GNB) has severely challenged antimicrobial therapy. Many CR GNB isolates are only susceptible to polymyxins; however, therapy with polymyxins and other potentially active antibiotics presents some drawbacks, which have discouraged their use in monotherapy. In this context, along with strong pre-clinical evidence of benefit in combining antimicrobials against CR GNB, the clinical use of combination therapy has been raised as an interesting strategy to overcome these potential limitations of a single agent. Polymyxins, tigecycline and even carbapenems are usually the cornerstone agents in combination schemes. Optimization of the probability to attain the pharmacokinetic/pharmacodynamic targets by both cornerstone drug and adjuvant drug is of paramount importance to achieve better clinical and microbiological outcomes. Clinical evidence of the major drugs utilized in combination schemes and how they should be prescribed considering pharmacokinetic/pharmacodynamic characteristics against CR GNB will be reviewed in this article.

Antibacterial activity of eravacycline (TP-434), a novel fluorocycline, against hospital and community pathogens

Eravacycline (TP-434 or 7-fluoro-9-pyrrolidinoacetamido-6-demethyl-6-deoxytetracycline) is a novel fluorocycline that was evaluated for antimicrobial activity against panels of recently isolated aerobic and anaerobic Gram-negative and Gram-positive bacteria. Eravacycline showed potent broad-spectrum activity against 90% of the isolates (MIC90) in each panel at concentrations ranging from ≤0.008 to 2 μg/ml for all species panels except those of Pseudomonas aeruginosa and Burkholderia cenocepacia (MIC90 values of 32 μg/ml for both organisms). The antibacterial activity of eravacycline was minimally affected by expression of tetracycline-specific efflux and ribosomal protection mechanisms in clinical isolates. Furthermore, eravacycline was active against multidrug-resistant bacteria, including those expressing extended-spectrum β-lactamases and mechanisms conferring resistance to other classes of antibiotics, including carbapenem resistance. Eravacycline has the potential to be a promising new intravenous (i.v.)/oral antibiotic for the empirical treatment of complicated hospital/health care infections and moderate-to-severe community-acquired infections.

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.

Treatment of carbapenem-resistant Klebsiella pneumoniae: the state of the art

The increasing incidence of carbapenem-resistant Klebsiella pneumoniae (CR-KP) fundamentally alters the management of patients at risk to be colonized or infected by such microorganisms. Owing to the limitation in efficacy and potential for toxicity of the alternative agents, many experts recommend using combination therapy instead of monotherapy in CR-KP-infected patients. However, in the absence of well-designed comparative studies, the best combination for each infection type, the continued role for carbapenems in combination therapy and when combination therapy should be started remain open questions. Herein, the authors revise current microbiological and clinical evidences supporting combination therapy for CR-KP infections to address some of these issues.

KPC - 3 Klebsiella pneumoniae ST258 clone infection in postoperative abdominal surgery patients in an intensive care setting: analysis of a case series of 30 patients

BACKGROUND

Abdominal surgery carries significant morbidity and mortality, which is in turn associated with an enormous use of healthcare resources. We describe the clinical course of 30 Intensive Care Unit (ICU) patients who underwent abdominal surgery and showed severe infections caused by Klebsiella pneumoniae sequence type (ST) 258 producing K. pneumoniae carbapenemase (KPC-Kp). The aim was to evaluate risk factors for mortality and the impact of a combination therapy of colistin plus recommended regimen or higher dosage of tigecycline.

METHODS

A prospective assessment of severe monomicrobial KPC-Kp infections occurring after open abdominal surgery carried out from August 2011 to August 2012 in the same hospital by different surgical teams is presented. Clinical and surgical characteristics, microbiological and surveillance data, factors associated with mortality and treatment regimens were analyzed. A combination regimen of colistin with tigecycline was used. A high dose of tigecycline was administered according to intra-abdominal abscess severity and MICs for tigecycline.

RESULTS

The mean age of the patients was 56.6 ± 15 and their APACHE score on admission averaged 22.72. Twenty out of 30 patients came from the surgical emergency unit. Fifteen patients showed intra-abdominal abscess, eight anastomotic leakage, four surgical site infection (SSI) and three peritonitis. The overall crude ICU mortality rate was 40% (12 out of 30 patients). Twelve of the 30 patients were started on a combination treatment of high-dose tigecycline and intravenous colistin. A significantly lower mortality rate was observed among those patients compared to patients treated with approved dose of tigecycline plus colistin. No adverse events were reported with high doses of tigecycline.

CONCLUSIONS

Critically-ill surgical patients are prone to severe post-surgical infectious complications caused by KPC-Kp. Timely microbiological diagnosis and optimizing antibiotic dosing regimens are essential to prevent worse outcomes. Further studies and well-controlled clinical trials are needed to define the optimal treatment of infections by KPC-Kp and, more generally, carbapenem-resistant bacteria.

Surveillance and management of multidrug-resistant microorganisms

Multidrug-resistant organisms are an established and growing worldwide public health problem and few therapeutic options remain available. The traditional antimicrobials (glycopeptides) for multidrug-resistant Gram-positive infections are declining in efficacy. New drugs that are presently available are linezolid, daptomicin and tigecycline, which have well-defined indications for severe infections, and talavancin, which is under Phase III trial for hospital-acquired pneumonia. Unfortunately the therapies available for multidrug-resistant Gram-negatives, including carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae, are limited to only colistin and tigecycline. Both of these drugs are still not registered for severe infections, such as hospital acquired pneumonia. Consequently, as confirmed by scientific evidence, a multidisciplinary approach is needed. Surveillance, infection control procedures, isolation and antimicrobial stewardship should be implemented to reduce multidrug-resistant organism diffusion.

Tigecycline does not prolong corrected QT intervals in healthy subjects

We evaluated the effect of tigecycline (50-mg and 200-mg doses) on corrected QT (QTc) intervals and assessed safety and tolerability in a randomized, placebo-controlled, four-period crossover study of 48 (44 male) healthy volunteers aged 22 to 53 years. Fed subjects received tigecycline (50 mg or 200 mg) or placebo in a blinded fashion or an open-label oral dose of moxifloxacin (400 mg) after 1 liter of intravenous fluid. Serial electrocardiograms were recorded before, and for 96 h after, dosing. Blood samples for tigecycline pharmacokinetics were collected after each recording. QTc intervals were corrected using Fridericia's correction (QTcF). Pharmacokinetic parameters were calculated using noncompartmental methods with potential relationships examined using linear mixed-effects modeling. Adverse events were recorded. The upper limits of the 90% confidence interval for the mean difference between both tigecycline doses and placebo for all time-matched QTcF interval changes from baseline were <5 ms. The tigecycline concentrations initially declined rapidly and then more slowly. In the group given 50 mg of tigecycline, the pharmacokinetic parameters and means were as follows: maximum concentration of drug in serum (C(max)), 432 ng/ml; area under the concentration-time curve from time zero extrapolated to infinity (AUC0-∞), 2,366 ng · h/ml; clearance (CL), 21.1 liters/h; volume of distribution at steady state (V(ss)), 610 liters; and terminal half-life (t(1/2)), 22.1 h. Proportional or similar values were found for the group given 200 mg of tigecycline. Linear mixed-effects modeling failed to show an effect on QTcF values by tigecycline concentrations (P = 0.755). Tigecycline does not prolong the QTc interval in healthy subjects. This study has been registered at ClinicalTrials.gov under registration no. NCT01287793.

Antimicrobial resistance in internal medicine wards

Antimicrobial resistance is a global medical problem, affecting most bacterial pathogens. The major challenges are currently posed by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), Enterobacteriaceae producing extended-spectrum-beta-lactamases (ESBL) and carbapenemases, and multi-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii. Therapeutic options are very limited and, in some cases, virtually unavailable. This article provides an overview of the recent epidemiological trends exhibited by the most important multi-resistant pathogens, and of the treatment options that are currently available for these infections.

Potential role of tigecycline in the treatment of community-acquired bacterial pneumonia

Tigecycline is a member of the glycylcycline class of antimicrobials, which is structurally similar to the tetracycline class. It demonstrates potent in vitro activity against causative pathogens that are most frequently isolated in patients with community-acquired bacterial pneumonia (CABP), including (but not limited to) Streptococcus pneumoniae (both penicillin-sensitive and -resistant strains), Haemophilus influenzae and Moraxella catarrhalis (including β-lactamase-producing strains), Klebsiella pneumoniae, and ‘atypical organisms’ (namely Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila). Comparative randomized clinical trials to date performed in hospitalized patients receiving tigecycline 100 mg intravenous (IV) × 1 and then 50 mg IV twice daily thereafter have demonstrated efficacy and safety comparable to the comparator agent. Major adverse effects were primarily gastrointestinal in nature. Tigecycline represents a parenteral monotherapy option in hospitalized patients with CABP (especially in patients unable to receive respiratory fluoroquinolones). However, alternate and/or additional therapies should be considered in patients with more severe forms of CABP in light of recent data of increased mortality in patients receiving tigecycline for other types of severe infection.

In vitro activity of tigecycline and comparators on Acinetobacter spp. isolates collected from patients with bacteremia and MIC change during the Tigecycline Evaluation and Surveillance Trial, 2004 to 2008

The Tigecycline Evaluation and Surveillance Trial is a global surveillance study established in 2004 to monitor the activity of tigecycline, a new glycylcycline, and several comparators against an array of important Gram-positive and Gram-negative pathogens. In this study, we examined 1591 isolates of Acinetobacter from blood samples collected from 352 centers globally between 2004 and 2008. Tigecycline showed an MIC(90) (1 microg/mL) globally, with a maximum regional value of 4 microg/mL (Middle East) reported. Antimicrobial susceptibility was notably higher among nonintensive care unit (non-ICU) isolates than isolates collected from ICUs. Carbapenem-resistant Acinetobacter were more prevalent in the Middle East, Latin America, and Asia/Pacific rim than in Europe or North America. Tigecycline creep was noted between 2004 and 2007, corresponding closely to changes in MIC(90).

Factors associated with adherence to guidelines for the use of tigecycline in a tertiary care hospital

We assessed the adherence to the prescribing hospital protocol for tigecycline and factors associated with noncompliance. A total of 103 patients were included in the study. In 23 (22.3%) patients, tigecycline was not administered according to the protocol, mostly because of the availability of other therapeutic alternatives and prescription for indications that were not included in the guidelines. factors independently associated with nonadherence to the protocol were community-acquired infection (OR, 14.01; 95% CI, 1.54-127.12; P=0.019), and empirical tigecycline treatment (OR, 6.97; 95% CI, 0.88-55.40; P=0.066). penicillin allergy (OR, 0.004; 95% CI, 0.000-0.071; P=0.001) and previous antibiotic treatment (OR, 0.025; 95% CI, 0.003-0.233; P=0.001) were factors associated with adherence to the hospital protocol. A positive time trend between total number of prescriptions and non-compliant prescriptions with the protocol was observed (Spearman's rho coefficient 0.971; P=0.001). Adherence to tigecycline protocol could be improved by focusing on protocols for community-acquired infections, mainly skin and soft tissue infections.

Successful treatment of pan-resistant Klebsiella pneumoniae pneumonia and bacteraemia with a combination of high-dose tigecycline and colistin

The spread of antimicrobial resistance among members of the Enterobacteriaceae is a significant clinical threat. We report the treatment of pan-resistant Klebsiella pneumoniae bacteraemia with combination tigecycline and colistin in a 49-year-old male and review available therapeutic options. Despite a poor prognosis, the patient recovered, but remains colonized with the pan-resistant isolate.

Detection and treatment options for Klebsiella pneumoniae carbapenemases (KPCs): an emerging cause of multidrug-resistant infection

Bacteria producing Klebsiella pneumoniae carbapenemases (KPCs) are rapidly emerging as a cause of multidrug-resistant infections worldwide. Bacterial isolates harbouring these enzymes are capable of hydrolysing a broad spectrum of beta-lactams including the penicillins, cephalosporins, carbapenems and monobactam. Detection of isolates harbouring carbapenemases can be inconsistent using automated systems, often requiring subsequent confirmatory tests. Phenotypic methods utilizing boronic acid disc tests have demonstrated promising results and appear practical for use in clinical microbiology laboratories. Treatment of infection caused by KPC bacteria is particularly worrisome as the carbapenems are often agents of the last resort for resistant Gram-negative infections. The optimal treatment of infections caused by KPC bacteria is not well established and clinical outcome data remain sparse. We reviewed the current literature regarding clinical outcomes following KPC infections, with a specific effort to summarize the clinical data available for specific antimicrobial agents. A total of 15 papers involving 55 unique patient cases were reviewed. While the total number of patients is relatively small, some useful insights could still be gathered to guide clinicians in the management of KPC infections. Tigecycline and the aminoglycosides were associated with positive outcomes in the majority of cases. Clinical success rates were low when the polymyxins were used as monotherapy, but were much higher when they were used in combination. Studies examining combination therapy and well-controlled clinical trials are needed to ascertain the optimal treatment of infections caused by KPC bacteria.