Efficacy and safety of tigecycline: a systematic review and meta-analysis

Cefepime combined with amoxicillin/clavulanic acid: a new choice for the KPC-producing K. pneumoniae infection

OBJECTIVE

Clinical treatment for blaKPC-positive Klebsiella pneumoniae isolates is challenging because the recommended antibiotic options are limited and are extraordinarily expensive. This study aimed to explore a new therapy for infection caused by KPC-producing K. pneumoniae.

METHODS

Patients with blaKPC-positive K. pneumoniae infection, were prospectively screened and were categorised into two groups: patients in the study group received a combination-based therapy of cefepime and amoxicillin/clavulanic acid and the control group received tigecycline-based therapy. The pathogen clearance rate, 28-day mortality and cost of the antibiotic treatment were compared between the two groups. Moreover, the checkerboard microdilution method was performed to determine the synergy between cefepime and amoxicillin/clavulanic acid in vitro.

RESULTS

Twenty-six and 25 cases were enrolled in the study and control groups. The mortality and the overall pathogen clearance rate showed no significant differences (P=0.311 and P=0.447). Both the total cost and the portion of the cost not covered by insurance were higher for the control group compared to the study group (both P<0.001). Consistently, synergy (65.4%) and partial synergy (26.9%) were the main effects.

CONCLUSIONS

In contrast to the currently recommended tigecycline-based therapy, cefepime and amoxicillin/clavulanic acid combination was an effective and economical option to KPC-KP infection in China.

Mortality burden related to infection with carbapenem-resistant Gram-negative bacteria among haematological cancer patients: a retrospective cohort study

OBJECTIVES

Carbapenem-resistant Gram-negative bacteria (CRGNB) pose a clinical challenge. We attempted to estimate the mortality burden of CRGNB among haematological cancer patients.

METHODS

This was a retrospective cohort study. We included adult patients hospitalized in the haemato-oncological/bone marrow transplantation departments for chemotherapy, between 2008 and 2014, with Gram-negative aerobic bacteraemia. We compared patients with CRGNB and carbapenem-susceptible Gram-negative bacteraemia (CSGNB). The primary outcome was 14 day all-cause mortality. In addition, we assessed 1 year survival. Multivariable logistics regression analysis and adjusted Cox regression analysis were conducted. Analyses were adjusted to the propensity for CRGNB bacteraemia.

RESULTS

The cohort included mostly young patients (mean age 50.1 years) with acute leukaemia (264/423, 62.4%) and the median absolute neutrophil count at bacteraemia onset was 0 × 10(9)/L. The unadjusted 14 day mortality rate was higher for patients with CRGNB compared with CSGNB [45.6% (47/103) versus 15% (48/320), respectively (P < 0.001)]. Adjusting to baseline prognostic factors, infection characteristics and the propensity score retained a significant association between CRGNB and 14 day mortality (OR 5.14, 95% CI 2.32-11.38). Including only the first bacteraemic episode per patient, 1 year mortality was 74.7% (68/91) for patients with CRGNB versus 49.8% (119/239) for patients with CSGNB (P < 0.001). Adjusting for risk factors associated with 1 year mortality, the HR for mortality with CRGNB was 1.48 (95% CI 1-2.2). CRGNB bacteraemia was associated with several risk factors for mortality, including inappropriate empirical antibiotic treatment and less effective definitive antibiotics.

CONCLUSIONS

This study demonstrated a significant adjusted association between CRGNB and mortality up to 1 year among haemato-oncological patients receiving chemotherapy.

Clinical response and mortality in tigecycline complicated intra-abdominal infection and complicated skin and soft-tissue infection trials

An imbalance in all-cause mortality was noted in tigecycline phase 3 and 4 comparative clinical trials across all studied indications. We investigated clinical failure and mortality in phase 3 and 4 complicated skin and soft-tissue infection (cSSTI) and complicated intra-abdominal infection (cIAI) tigecycline trials using descriptive analyses of a blinded adjudication of mortality and multivariate regression analyses. Attributable mortality analyses of cSSTI revealed death due to infection in 0.1% of each treatment group (P=1.000). In cIAI, there were no significant differences between tigecycline (1.2%) and comparator (0.7%) subjects who died due to infection (P=0.243). For cIAI clinical failure, treatment interaction with organ dysfunction was observed with no difference observed between clinical cure for tigecycline (85.4%) and comparator (76.7%) treatment groups (odds ratio=0.58, 95% confidence interval 0.28-1.19). Tigecycline-treated subjects had more adverse events of secondary pneumonias (2.1% vs. 1.2%) and more adverse events of secondary pneumonias with an outcome of death (0.5% vs. 0.1%). These analyses do not suggest that tigecycline is a factor either for failure (cSSTI and cIAI studies) or for death (cIAI studies).

Treatment of community-acquired pneumonia

Community-acquired pneumonia is the sixth leading cause of death in the USA. Adherence to the 2007 Infectious Diseases Society of America/American Thoracic Society community-acquired pneumonia guidelines has been associated with improved clinical outcomes. However, choice between guideline-recommended treatments is at the discretion of the prescribing clinician. This review is intended to discuss the characteristics of these treatment options including dosing frequency, dose adjustment for renal/hepatic dysfunction, serious/common adverse events, drug interactions, lung penetration, pharmacokinetic-pharmacodynamic target and effect of obesity to help guide antimicrobial selection. An increasing portion of patients are receiving expanded empiric coverage for methicillin-resistant Staphylococcus aureus as recommended by the American Thoracic Society and Infectious Diseases Society of America for healthcare-associated pneumonia. However, this expanded coverage may not be achieving the desired improvements in clinical outcomes. We expect this increasingly diverse spectrum of patients with pneumonia to eventually result in the merger of these two guidelines to include all patients with pneumonia.

Global dissemination of extensively drug-resistant carbapenemase-producing Enterobacteriaceae: clinical perspectives on detection, treatment and infection control

The prevalence of carbapenem-resistant Gram-negative bacilli is on the rise worldwide, posing a major public health threat. Previously, this was mostly a problem in Pseudomonas and Acinetobacter, but during the last decade, carbapenem resistance has escalated in medically important species such as Klebsiella pneumoniae and Escherichia coli. In particular, the rising trend in E. coli is of concern, as this may lead to almost untreatable community-acquired infections. Resistance is conferred by carbapenemases, which are beta-lactamases that can breakdown essentially all beta-lactams. Moreover, bacteria carrying these resistance determinants are often resistant to other treatment options, due to the frequent co-acquisition of non-beta-lactam resistance genes located on the same mobile genetic elements. The detection of carbapenemase-producing Enterobacteriaceae (CPE) is a challenge, because some carbapenemases produce relatively discrete levels of carbapenem resistance. Current clinical evidence for treatment guidance is limited and based on retrospective observational studies and case reports. Existing data support the use of combination therapy for treatment of severe infections caused by CPE. Combination regimens including colistin, carbapenems, tigecycline, aminoglycosides and fosfomycin have been used. Randomized controlled studies of combination regimens are ongoing and may help to determine the optimal therapy. Novel beta-lactamase inhibitors may also have a role in future treatment of these infections. Strict infection control measures including isolation or cohort care of affected patients as well as contact tracing and active screening are needed to curb the spread of CPE. In this review, we provide a clinical perspective on the management of patients infected or colonized with CPE.

Activity of antimicrobial combinations against KPC-2-producing Klebsiella pneumoniae in a rat model and time-kill assay

This study evaluated the efficacy of tigecycline (TIG), polymyxin B (PMB), and meropenem (MER) in 80 rats challenged with Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae infection. A time-kill assay was performed with the same strain. Triple therapy and PMB+TIG were synergistic, promoted 100% survival, and produced negative peritoneal cultures, while MER+TIG showed lower survival and higher culture positivity than other regimens (P = 0.018) and was antagonistic. In vivo and in vitro studies showed that combined regimens, except MER+TIG, were more effective than monotherapies for this KPC-producing strain.

Carbapenemase-producing Gram-negative bacteria: current epidemics, antimicrobial susceptibility and treatment options

ABSTRACT 

Carbapenemases, with versatile hydrolytic capacity against β-lactams, are now an important cause of resistance of Gram-negative bacteria. The genes encoding for the acquired carbapenemases are associated with a high potential for dissemination. In addition, infections due to Gram-negative bacteria with acquired carbapenemase production would lead to high clinical mortality rates. Of the acquired carbapenemases, Klebsiella pneumoniae carbapenemase (Ambler class A), Verona integron-encoded metallo-β-lactamase (Ambler class B), New Delhi metallo-β-lactamase (Ambler class B) and many OXA enzymes (OXA-23-like, OXA-24-like, OXA-48-like, OXA-58-like, class D) are considered to be responsible for the worldwide resistance epidemics. As compared with monotherapy with colistin or tigecycline, combination therapy has been shown to effectively lower case-fatality rates. However, development of new antibiotics is crucial in the present pandrug-resistant era.

Antibiotic Management of Methicillin-Resistant Staphylococcus aureus–Associated Acute Pulmonary Exacerbations in Cystic Fibrosis

Objective: To review the treatment of methicillin-resistant Staphylococcus aureus (MRSA)–associated acute pulmonary exacerbations (APEs) in cystic fibrosis (CF). Data Sources: A search of PubMed, MEDLINE, Cochrane Library and Clinicaltrials.gov databases through November 2014 was conducted using the search terms Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, pulmonary exacerbations, and cystic fibrosis. Study Selection and Data Extraction: All English-language research articles, case reports, and case series were evaluated. A total of 185 articles were identified related to MRSA and CF; 30 articles that studied treatments of MRSA APE in CF were included. Data Synthesis: The persistent presence of MRSA in the respiratory tract of patients with CF has been associated with higher morbidity and an increased risk of death. Limited clinical data exist supporting the efficacy of any specific antimicrobial currently available for the treatment of APE secondary to MRSA. Conclusions: Data extrapolated from other populations suggest that vancomycin and linezolid are appropriate first-line treatment options for the treatment of APE secondary to MRSA. Second-line options include doxycycline or minocycline and trimethoprim/sulfamethoxazole, each of which may be useful in patients coinfected with other respiratory pathogens, for which they may provide overlapping coverage. Ceftaroline and ceftobiprole are newer antibiotics that appear to have a potential role in the treatment of APE in CF, but the latter is not currently available to the US market. Although potentially useful, clindamycin is limited by high rates of resistance, telavancin is limited by its toxicity profile, and tigecycline is limited by a lack of demonstrated efficacy for infections that are similar to that seen in the CF population. Studies investigating the clinical utility of the above-cited antibiotics for APE in CF secondary to MRSA are desperately needed to broaden the treatment armamentarium for this medical condition.

Tigecycline : a critical safety review

INTRODUCTION

The emergence of multidrug-resistant (MDR) infections has been extensively observed worldwide and has become a priority issue over past decade. Tigecycline , a broad spectrum antibiotic covering against many MDR organisms, has been widely used. However, recent meta-analysis studies have raised a concern for its efficacy and safety. Reviewing tigecycline safety data would enhance the appropriate use of this medication.

AREAS COVERED

This article reviews the safety profile of tigecycline, including its side effects and drug interactions.

EXPERT OPINION

The increased mortality associated with tigecycline is not yet well understood. Based on current evidence, alternative options must be prioritized over tigecycline if available. When tigecycline use is warranted, vigilant observation to identify any breakthrough infections and careful monitoring of progression of the original infection are highly recommended. Considering a second agent (either for synergism or enhancing coverage) may be required.

Antimicrobial resistance in Acinetobacter baumannii: From bench to bedside

Acinetobacter baumannii (A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrug-resistant A. baumannii (MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections.

An updated approach to healthcare-associated meningitis

Among hospital-associated infections, healthcare-associated central nervous system infections are quite important because of high morbidity and mortality rates. The causative agents of healthcare-associated meningitis differ according to the status of immune systems and underlying diseases. The most frequent agents are Gram-negative bacilli (Pseudomonas spp., Acinetobacter spp., Escherichia coli and Klebsiella pneumoniae) and Gram-positive cocci (Staphylococcus aureus and coagulase-negative staphylococci). There are currently several problems in the treatment strategies of healthcare-associated meningitis due to a globally increasing resistance problem. Strategies targeting multidrug-resistant pathogens are especially limited. This review focuses on healthcare-associated meningitis and the current treatment strategies with a particular focus on methicillin-resistant Staphylococcus aureus (MRSA) meningitis.

High-dose tigecycline and colistin for successful treatment of disseminated carbapenem-resistant Klebsiella pneumoniae infection in a liver transplant recipient

Solid organ transplantation (SOT) is a risk factor for the acquisition of carbapenem-resistant Klebsiella pneumoniae. This infection is associated with a high mortality rate given the limited armamentarium of antibiotics for multidrug-resistant organisms along with continued immunosuppression to prevent graft rejection. We report a case of carbapenem-resistant K. pneumoniae pneumonia, bacteraemia and intra-abdominal infection in a newly transplanted liver recipient. The patient was successfully treated with a long course of high-dose tigecycline and colistin, along with surgical drainage. We discuss SOT-relevant epidemiology, therapeutic options and the rationale for our treatment choice.

Treatment of KPC-producing Enterobacteriaceae: suboptimal efficacy of polymyxins

Treatment of Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae infections (KPC-EI) remains a challenge. Combined therapy has been proposed as the best choice, but there are no clear data showing which combination therapy is superior. Our aim was to evaluate the effectiveness of antimicrobial regimens for treating KPC-EI. This was a retrospective cohort study of KPC-EI nosocomial infections (based on CDC criteria) between October 2009 and June 2013 at three tertiary Brazilian hospitals. The primary outcomes were the 30-day mortality for all infections and the 30-day mortality for patients with bacteraemia. Risk factors for mortality were evaluated by comparing clinical variables of survivors and nonsurvivors. In this study, 118 patients were included, of whom 78 had bacteraemia. Catheter-related bloodstream infections were the most frequent (43%), followed by urinary tract infections (n = 27, 23%). Monotherapy was used in 57 patients and combined treatment in 61 patients. The most common therapeutic combination was polymyxin plus carbapenem 20 (33%). Multivariate analysis for all infections (n = 118) and for bacteremic infections (n = 78) revealed that renal failure at the end of treatment, use of polymyxin and older age were prognostic factors for mortality. In conclusion, polymyxins showed suboptimal efficacy and combination therapy was not superior to monotherapy.

Clinical management of infections caused by multidrug-resistant Enterobacteriaceae

Enterobacteriaceae showing resistance to cephalosporins due to extended-spectrum β-lactamases (ESBLs) or plasmid-mediated AmpC enzymes, and those producing carbapenemases have spread worldwide during the last decades. Many of these isolates are also resistant to other first-line agents such as fluoroquinolones or aminoglycosides, leaving few available options for therapy. Thus, older drugs such as colistin and fosfomycin are being increasingly used. Infections caused by these bacteria are associated with increased morbidity and mortality compared with those caused by their susceptible counterparts. Most of the evidence supporting the present recommendations is from in vitro data, animal studies, and observational studies. While carbapenems are considered the drugs of choice for ESBL and AmpC producers, recent data suggest that certain alternatives may be suitable for some types of infections. Combined therapy seems superior to monotherapy in the treatment of invasive infections caused by carbapenemase-producing Enterobacteriaceae. Optimization of dosage according to pharmacokinetics/pharmacodynamics data is important for the treatment of infections caused by isolates with borderline minimum inhibitory concentration due to low-level resistance mechanisms. The increasing frequency and the rapid spread of multidrug resistance among the Enterobacteriaceae is a true and complex public health problem.

Infections Caused by Acinetobacter baumannii in Recipients of Hematopoietic Stem Cell Transplantation

Acinetobacter baumannii (A. baumannii) is a Gram-negative, strictly aerobic, non-fermentative coccobacillus, which is widely distributed in nature. Recently, it has emerged as a major cause of health care-associated infections (HCAIs) in addition to its capacity to cause community-acquired infections. Risk factors for A. baumannii infections and bacteremia in recipients of hematopoietic stem cell transplantation include: severe underlying illness such as hematological malignancy, prolonged use of broad-spectrum antibiotics, invasive instrumentation such as central venous catheters or endotracheal intubation, colonization of respiratory, gastrointestinal, or urinary tracts in addition to severe immunosuppression caused by using corticosteroids for treating graft versus host disease. The organism causes a wide spectrum of clinical manifestations, but serious complications such as bacteremia, septic shock, ventilator-associated pneumonia, extensive soft tissue necrosis, and rapidly progressive systemic infections that ultimately lead to multi-organ failure and death are prone to occur in severely immunocompromised hosts. The organism is usually resistant to many antimicrobials including penicillins, cephalosporins, trimethoprim-sulfamethoxazole, almost all fluoroquinolones, and most of the aminoglycosides. The recently increasing resistance to carbapenems, colistin, and polymyxins is alarming. Additionally, there are geographic variations in the resistance patterns and several globally and regionally resistant strains have already been described. Successful management of A. baumannii infections depends upon appropriate utilization of antibiotics and strict application of preventive and infection control measures. In uncomplicated infections, the use of a single active beta-lactam may be justified, while definitive treatment of complicated infections in critically ill individuals may require drug combinations such as colistin and rifampicin or colistin and carbapenem. Mortality rates in patients having bacteremia or septic shock may reach 70%. Good prognosis is associated with presence of local infection, absence of multidrug resistant strain, and presence of uncomplicated infection while poor outcome is associated with severe underlying medical illness, bacteremia, septic shock, multi-organ failure, HCAIs, admission to intensive care facilities for higher levels of care, and culture of certain aggressive genotypes of A. baumannii.

Monotherapy versus combination therapy for sepsis due to multidrug-resistant Acinetobacter baumannii: analysis of a multicentre prospective cohort

BACKGROUND

Treatment of multidrug-resistant Acinetobacter baumannii (MDRAB) infection presents a challenge because of the scarcity of available options. Even though combination therapy (CT) is frequently used in clinical practice, data are needed to support its use instead of monotherapy (MT).

METHODS

A prospective observational study was conducted in 28 Spanish hospitals. Patients with sepsis caused by MDRAB, defined according to strict criteria, and who received active antibiotic treatment (according to in vitro susceptibility testing) for at least 48 h, were included. The main outcome variable was all-cause 30 day mortality after initiation of targeted therapy. Multivariate analysis, including a propensity score (for receiving CT), was performed by Cox regression.

RESULTS

One hundred and one patients were included in the analysis; 68 (67.3%) received MT and 33 (32.7%) received CT. Pneumonia was the most common infection (50.5%), 68.6% of cases being associated with mechanical ventilation. Colistin (67.6%) and carbapenems (14.7%) were the most common drugs used in MT; colistin plus tigecycline (27.3%) and carbapenem plus tigecycline (12.1%) were the most frequent combinations. Crude 30 day mortality was 23.5% and 24.2% for the MT and CT groups, respectively (RR = 1.03; 95% CI 0.49-2.16; P = 0.94). Multivariate analysis of 30 day survival showed no trend towards reduced 30 day mortality with CT (HR = 1.35; 95% CI 0.53-3.44; P = 0.53). Subgroup analysis showed similar results.

CONCLUSIONS

Our data do not support an association of CT with reduced mortality in MDRAB infections. More data for specific types of infection and combinations are needed.

Tigecycline use in critically ill patients: a multicentre prospective observational study in the intensive care setting

PURPOSE

This prospective observational study aimed at describing prescription patterns of tigecycline and patient outcomes in 26 French intensive care units (ICU).

METHODS

Data of consecutive cases of adult patients treated with tigecycline were collected from the initiation until 7 days after the end of treatment. Response to treatment was classified as success, failure or undetermined and analyses were presented according to severity (SOFA score <7 or ≥7). Survival was recorded at 28 days.

RESULTS

A total of 156 patients were included (64% male, age 60 ± 15 years). At inclusion, 53% had a SOFA score ≥7; 93% had received prior anti-infective agents. Tigecycline was given as first-line treatment in 47% of patients, mostly in combination (67%), for intra-abdominal (IAI 56%), skin and soft tissue (SSTI 19%) or other infections. A total of 76% of the treated infections were hospital-acquired. Bacteraemia was reported in 12% of patients. Median treatment duration was 9 days. Tigecycline was prematurely stopped in 42% patients. The global success rate was 60% at the end of treatment, and significantly higher with treatment duration more than 9 days (76 vs. 47%, P < 0.001). Success rate was 65% for patients alive at the end of treatment. Success rates tended to decrease with illness severity, immunosuppression, bacteraemia and obesity. Survival rate at day 28 was 85% in the whole cohort and significantly higher in the less severely ill patients (P < 0.001).

CONCLUSIONS

Tigecycline success rates appear comparable to those reported in clinical studies in ICU with severe infections. Tigecycline could be an alternative in ICU patients.

Results of a Multicenter, Controlled, Randomized Clinical Trial Evaluating the Combination of Piperacillin/Tazobactam and Tigecycline in High-Risk Hematologic Patients With Cancer With Febrile Neutropenia

Purpose

Empiric antibiotic monotherapy is considered the standard of treatment for febrile neutropenic patients with cancer, but this approach may be inadequate because of the increasing prevalence of infections caused by multidrug resistant (MDR) bacteria.

Patients and Methods

In this multicenter, open-label, randomized, superiority trial, adult, febrile, high-risk neutropenic patients (FhrNPs) with hematologic malignancies were randomly assigned to receive piperacillin/tazobactam (4.5 g intravenously every 8 hours) with or without tigecycline (50 mg intravenously every 12 hours; loading dose 100 mg). The primary end point was resolution of febrile episode without modifications of the initial allocated treatment.

Results

Three hundred ninety FhrNPs were enrolled (combination/monotherapy, 187/203) and were included in the intention-to-treat analysis (ITTA). The ITTA revealed a successful outcome in 67.9% v 44.3% of patients who had received combination therapy and monotherapy, respectively (127/187 v 90/203; absolute difference in risk (adr), 23.6%; 95% CI, 14% to 33%; P < .001). The combination regimen proved better than monotherapy in bacteremias (adr, 32.8%; 95% CI, 19% to 46%; P < .001) and in clinically documented infections (adr, 36%; 95% CI, 9% to 64%; P < .01). Mortality and number of adverse effects were limited and similar in the two groups.

Conclusion

The combination of piperacillin/tazobactam and tigecycline is safe, well tolerated, and more effective than piperacillin/tazobactam alone in febrile, high-risk, neutropenic hematologic patients with cancer. In epidemiologic settings characterized by a high prevalence of infections because of MDR microorganisms, this combination could be considered as one of the first-line empiric antibiotic therapies.

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.

In vitro and in vivo activities of tigecycline-colistin combination therapies against carbapenem-resistant Enterobacteriaceae

We assessed the activity of tigecycline (TGC) combined with colistin (COL) against carbapenem-resistant enterobacteria. Synergy occurred in vitro against the majority of isolates, with the exception of Serratia marcescens. In a simple animal model (Galleria mellonella), TGC-COL was superior (P < 0.01) in treating Escherichia coli, Klebsiella pneumoniae, and Enterobacter infections, including those with TGC-COL resistance. Clinical studies are needed to determine whether TGC-COL regimens may be a viable option.

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

OBJECTIVES

An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli.

METHODS

E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation.

RESULTS

The anthracycline Antibiotic 301A(1) was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure-activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A(1) abolishes activity.

CONCLUSIONS

Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives.

Major variation in MICs of tigecycline in Gram-negative bacilli as a function of testing method

Tigecycline is one of the few remaining therapeutic options for extensively drug-resistant (XDR) Gram-negative bacilli (GNB). MICs of tigecycline to Acinetobacter baumannii have been reported to be elevated when determined by the Etest compared to determinations by the broth microdilution (BMD) method. The study aim was to compare the susceptibility of GNB to tigecycline by four different testing methods. GNB were collected from six health care systems (25 hospitals) in southeast Michigan from January 2010 to September 2011. Tigecycline MICs among A. baumannii, carbapenem-resistant Enterobacteriaceae (CRE), extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, and susceptible Enterobacteriaceae isolates were determined by Etest, BMD, Vitek-2, and MicroScan. Nonsusceptibility was categorized as a tigecycline MIC of ≥4 μg/ml for both A. baumannii and Enterobacteriaceae. The study included 4,427 isolates: 2,065 ESBL-producing Enterobacteriaceae, 1,105 A. baumannii, 888 susceptible Enterobacteriaceae, and 369 CRE isolates. Tigecycline nonsusceptibility among A. baumannii isolates was significantly more common as determined by Etest compared to that determined by BMD (odds ratio [OR], 10.3; P<0.001), MicroScan (OR, 12.4; P<0.001), or Vitek-2 (OR, 9.4; P<0.001). These differences were not evident with the other pathogens. Tigecycline MICs varied greatly according to the in vitro testing methods among A. baumannii isolates. Etest should probably not be used by laboratories for tigecycline MIC testing of A. baumannii isolates, since MICs are significantly elevated with Etest compared to those determined by the three other methods.

Effectiveness of tigecycline-based versus colistin- based therapy for treatment of pneumonia caused by multidrug-resistant Acinetobacter baumannii in a critical setting: a matched cohort analysis

Background

Colistin and tigecycline have both been shown good in vitro activity among multi-drug resistant Acinetobacter baumannii (MDRAB). A comparative study of colistin versus tigecycline for MDRAB pneumonia is lacking.

Methods

The study enrolled adults with MDRAB pneumonia admitted to intensive care units at a referral medical center during 2009–2010. Since there were no standardized minimum inhibitory concentration (MIC) interpretation criteria of tigecycline against A. baumannii, MIC of tigecycline was not routinely tested at our hospital. During the study periods, MIC of colistin was not routinely tested also. We consider both colistin and tigecycline as definite treatments of MDRAB pneumonia. Patients who received tigecycline were selected as potential controls for those who had received colistin. We performed a propensity score analysis, by considering the criteria of age, gender, underlying diseases, and disease severity, in order to match and equalize potential prognostic factors and severity in the two groups.

Results

A total of 294 adults with MDRAB pneumonia were enrolled, including 119 who received colistin and 175 who received tigecycline. We matched 84 adults who received colistin with an equal number of controls who received tigecycline. The two well matched cohorts share similar characteristics: the propensity scores are colistin: 0.37 vs. tigecycline: 0.37, (P = .97); baseline creatinine (1.70 vs. 1.81, P = .50), and the APACHE II score (21.6 vs. 22.0, P = .99). The tigecycline group has an excess mortality of 16.7% (60.7% vs. 44%, 95% confidence interval 0.9% – 32.4%, P = .04). The excess mortality of tigecycline is significant only among those with MIC >2 μg/mL (10/12 vs. 37/84, P = .01), but not for those with MIC ≦ 2 μg/mL (4/10 vs. 37/84, P = .81).

Conclusions

Our data disfavors the use of tigecycline-based treatment in treating MDRAB pneumonia when tigecycline and colistin susceptibilities are unknown, since choosing tigecycline-based treatment might result in higher mortality. The excess mortality of tigecycline-based group may be related to higher MIC of tigecycline (> 2 μg/mL). Choosing tigecycline empirically for treating MDRAB pneumonia in the critical setting should be cautious.

Treatment of multidrug-resistant Gram-negative infections in children

Antibiotic resistance in conjunction with the erosion of the drug development pipeline may lead us into a bleak future, a "post-antibiotic era." Because of a shortage of studies addressing treatment options for multidrug-resistant Gram-negative (MDRGN) infections in children, data must be extrapolated from the adult literature. However, even adult studies are limited by significant methodological flaws. We are in urgent need of pediatric specific pharmacokinetic/pharmacodynamic data for agents with activity against MDRGN infections as well as improved clinical outcomes studies. For the time being, we must rely on in vitro studies, observational data, and clinical experience to guide our therapeutic decisions. In this review, we discuss treatment considerations for infections caused by extended-spectrum β-lactamase-producing organisms, AmpC β-lactamase-producing organisms, carbapenem-resistant Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii in the pediatric population.

Efficacy of tigecycline for the treatment of complicated intra-abdominal infections in real-life clinical practice from five European observational studies

OBJECTIVES

Tigecycline is a broad-spectrum antibiotic approved for the treatment of complicated intra-abdominal infections (cIAIs). The efficacy of tigecycline when administered as monotherapy or in combination with other antibacterials in the treatment of cIAIs in routine clinical practice is described.

PATIENTS AND METHODS

Individual patient-level data were pooled from five European observational studies (July 2006 to October 2011).

RESULTS

A total of 785 cIAI patients who received tigecycline were included (mean age 63.1 ± 14.0 years). Of these, 56.6% were in intensive care units, 65.6% acquired their infection in hospital, 88.1% had at least one comorbidity and 65.7% had secondary peritonitis. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores at the beginning of treatment were 16.9 ± 7.6 (n = 614) and 7.0 ± 4.2 (n = 108), respectively, indicating high disease severity. Escherichia coli (41.8%), Enterococcus faecium (40.1%) and Enterococcus faecalis (21.1%) were the most frequently isolated pathogens; 49.1% of infections were polymicrobial and 17.5% were due to resistant pathogens. Overall, 54.8% (n = 430) received tigecycline as monotherapy and 45.2% (n = 355) as combination therapy for a mean duration of 10.6 days. Clinical response rates at the end of treatment were 77.4% for all patients (567/733), 80.6% for patients who received tigecycline as monotherapy (329/408), 75.2% for patients with a nosocomial infection (354/471), 75.8% for patients with an APACHE II score >15 (250/330) and 54.2% (32/59) for patients with a SOFA score ≥ 7.

CONCLUSIONS

In these real-life studies, tigecycline, alone and in combination, achieved favourable clinical response rates in patients with cIAI with a high severity of illness.

Safety and tolerability of tigecycline for the treatment of complicated skin and soft-tissue and intra-abdominal infections: an analysis based on five European observational studies

OBJECTIVES

Tigecycline is approved for the treatment of complicated skin and soft-tissue infections (cSSTIs) and complicated intra-abdominal infections (cIAIs) in adults. In this analysis the safety and tolerability profile of tigecycline (used alone or in combination) for the treatment of patients with approved indications of cSSTI and cIAI were examined under real-life clinical conditions.

PATIENTS AND METHODS

Individual patient-level data were pooled from five European observational studies (July 2006 to October 2011). A total of 254 cSSTI and 785 cIAI patients were included. The mean age was 63 years; 34.4% and 56.6% were in intensive care units, 90.9% and 88.1% had at least one comorbidity and mean Acute Physiology and Chronic Health Evaluation (APACHE) II scores at the beginning of treatment were 15.0 ± 7.9 and 16.9 ± 7.6, respectively.

RESULTS

Data on adverse events (AEs) were available for 198 cSSTI and 590 cIAI patients in three studies. Nausea and vomiting were reported in ≤ 2% of patients. The most common serious AEs were multi-organ failure (4.0% and 10.0% in cSSTI and cIAI patients, respectively) and sepsis (4.0% and 6.1%, respectively). Death was recorded for 24/254 (9.4%) cSSTI and 147/785 (18.7%) cIAI patients. Mortality rates were higher in the group with a baseline APACHE II score of >15 compared with those with a score of ≤ 15 (18.7% versus 3.5% for cSSTI patients and 23.8% versus 16.0% for cIAI patients). A similar trend was seen when cIAI patients were stratified by Sequential Organ Failure Assessment (SOFA) score.

CONCLUSIONS

The safety and tolerability of tigecycline, alone and in combination, are consistent with the level of critical illness among patients in these real-life studies.

Efficacy of tigecycline for the treatment of complicated skin and soft-tissue infections in real-life clinical practice from five European observational studies

OBJECTIVES

Tigecycline is an approved treatment for complicated skin and soft-tissue infections (cSSTIs). The efficacy of tigecycline as monotherapy or in combination with other antibacterials in the treatment of cSSTI in routine practice is described.

PATIENTS AND METHODS

Individual patient-level data were pooled from five European observational studies (July 2006 to October 2011).

RESULTS

A total of 254 cSSTI patients who received tigecycline were included (mean age 63.2 ± 14.9 years). Of these, 34.4% were in intensive care units, 54.5% acquired their infection in hospital and 90.9% had at least one comorbidity. Infection most commonly affected the limbs (62.4%) and 43.8% of infections were classified as necrotizing. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores at the beginning of treatment were 15.0 ± 7.9 (n = 205) and 5.8 ± 3.9 (n = 32), respectively, indicating high disease severity. Staphylococcus aureus (52.7%), Escherichia coli (18.0%) and Enterococcus faecium (12.0%) were the most frequently isolated pathogens; 32.9% of infections were polymicrobial and 30.5% were due to resistant pathogens. Overall, 71.8% received tigecycline as monotherapy and 28.2% as combination therapy for a mean duration of 12 days. Clinical response rates at the end of treatment were 79.6% for all patients who received the standard dosage (183/230), 86.7% for patients who received tigecycline as monotherapy (143/165), 75.0% for patients with a nosocomial infection (96/128), 75.3% for patients with an APACHE II score >15 (61/81) and 58.3% for patients with a SOFA score ≥ 7 (7/12).

CONCLUSIONS

In these real-life studies, tigecycline, alone and in combination, achieved favourable clinical response rates in patients with cSSTI with a high severity of illness.

Prescription behaviours for tigecycline in real-life clinical practice from five European observational studies

OBJECTIVES

There is limited information on the use of tigecycline in real-life clinical practice. This analysis aims to identify and understand tigecycline prescribing patterns and associated patient outcomes for approved indications.

PATIENTS AND METHODS

A pooled analysis of patient-level data collected on the prescription of tigecycline in five European observational studies (July 2006 to October 2011) was conducted.

RESULTS

A total of 1782 patients who received tigecycline were included in the analysis. Of these patients, 61.6% were male, the mean age was 63.4 ± 14.7 years, 56.4% were in intensive care units, 80.2% received previous antibiotic treatment and 91% had one or more comorbid conditions. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores at the beginning of treatment were 17.7 ± 7.9 and 7.0 ± 4.0, respectively. The majority of patients (58.3%) received tigecycline for treatment of complicated skin and soft-tissue infections (cSSTIs; n = 254) or complicated intra-abdominal infections (cIAIs; n = 785). Tigecycline was given at the standard dose (100 mg plus 50 mg twice daily) to 89.3% of patients for a mean duration of 11.1 ± 6.4 days. The main reasons for prescribing tigecycline were failure of previous therapy (46.1%), broad-spectrum antibiotic coverage (41.4%) and suspicion of a resistant pathogen (39.3%). Tigecycline was prescribed first-line in 36.3% of patients and as monotherapy in 50.4%. Clinical response rates to treatment with tigecycline alone or in combination were 79.6% (183/230; cSSTIs) and 77.4% (567/733; cIAIs).

CONCLUSIONS

Although tigecycline prescription behaviour showed some heterogeneity across the study sites, these results confirm a role for tigecycline in real-life clinical practice for the treatment of complicated infections, including those in critically ill patients, across Europe.

Resistance mechanisms and epidemiology of multiresistant pathogens in Europe and efficacy of tigecycline in observational studies

OBJECTIVES

Antimicrobial drug resistance is a growing problem in Europe and, even with differences in epidemiology, it is of great concern. The treatment of complicated skin and soft-tissue infections (cSSTIs) and complicated intra-abdominal infections (cIAIs) is hindered further by pathogens that are resistant to methicillin, carbapenems, third-generation cephalosporins and glycopeptides.

PATIENTS AND METHODS

An analysis of the microbiological results from five European observational studies (July 2006 to October 2011) evaluating the efficacy of tigecycline (prescribed as monotherapy or in combination with other antibacterials) for the treatment of cSSTI and cIAI is presented.

RESULTS

In total, 213 cSSTI and 623 cIAI patients were included; 34.4% and 56.6%, respectively, were critically ill in intensive care units. At baseline, at least one pathogen was isolated in 167 (78.4%) cSSTI and 464 (74.5%) cIAI patients, and 32.9% and 49.1% of infections were polymicrobial. In cSSTI, Staphylococcus aureus and Escherichia coli (52.7% and 18.0%, respectively) were the most frequently isolated pathogens, whereas in cIAI most infections were due to E. coli (41.8%), Enterococcus faecium (40.1%) and Enterococcus faecalis (21.1%). Clinical response was observed in >80% of patients with E. coli in both cIAI and cSSTI. In cSSTI patients, the clinical response rate to S. aureus was 80.8%. For cIAI, 77.4% of E. faecium and 79.5% of E. faecalis patients responded to treatment.

CONCLUSIONS

Tigecycline when given alone or in combination with other antibacterials appeared to be efficacious against multiple pathogens, affirming its role in real-life clinical practice as a broad-spectrum antibacterial for the treatment of patients with cSSTI and cIAI, including the critically ill, across Europe.

Carbapenem-resistant Enterobacteriaceae: a menace to our most vulnerable patients

The emergence of carbapenem-resistant Enterobacteriaceae (CRE) highlights the importance of effective antibiotics to maintain the safety of our health care system. Clinicians will encounter CRE as a cause of difficult-to-treat and often fatal infections in hospitalized patients. We review the mechanisms of carbapenem resistance, the dissemination and clinical impact of these resistant organisms, and challenges to their detection, treatment, and control.

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.

Antibiotic treatment of infections due to carbapenem-resistant Enterobacteriaceae: systematic evaluation of the available evidence

We sought to evaluate the effectiveness of the antibiotic treatment administered for infections caused by carbapenemase-producing Enterobacteriaceae. The PubMed and Scopus databases were systematically searched. Articles reporting the clinical outcomes of patients infected with carbapenemase-producing Enterobacteriaceae according to the antibiotic treatment administered were eligible. Twenty nonrandomized studies comprising 692 patients who received definitive treatment were included. Almost all studies reported on Klebsiella spp. In 8 studies, the majority of infections were bacteremia, while pneumonia and urinary tract infections were the most common infections in 12 studies. In 10 studies, the majority of patients were critically ill. There are methodological issues, including clinical heterogeneity, that preclude the synthesis of the available evidence using statistical analyses, including meta-analysis. From the descriptive point of view, among patients who received combination treatment, mortality was up to 50% for the tigecycline-gentamicin combination, up to 64% for tigecycline-colistin, and up to 67% for carbapenem-colistin. Among the monotherapy-treated patients, mortality was up to 57% for colistin and up to 80% for tigecycline. Certain regimens were administered to a small number of patients in certain studies. Three studies reporting on 194 critically ill patients with bacteremia showed individually significantly lower mortality in the combination arm than in the monotherapy arm. In the other studies, no significant difference in mortality was recorded between the compared groups. Combination antibiotic treatment may be considered the optimal option for severely ill patients with severe infections. However, well-designed randomized studies of specific patient populations are needed to further clarify this issue.

Adjuvant immunotherapies as a novel approach to bacterial infections

The rapid emergence of multidrug-resistant pathogens, especially Gram-negative bacteria and mycobacteria, represents one of the major medical challenges of the 21st century. The gradual loss of effective classical antibiotics for many bacterial pathogens, combined with an increasing population density and mobility, urgently calls for the development of novel treatments. Here, we discuss the potential of adjuvant immunotherapies to selectively stimulate protective immune responses as a treatment option for bacterial infections. In order to elicit appropriate immune responses and to avoid unwanted inflammatory tissue damage, it is essential to identify ligands and receptor pathways that specifically control protective responses at the site of infection. We summarize existing data and discuss suitable candidate targets for future immunotherapies of infectious diseases.

Patients enrolled in randomised clinical trials are not representative of critically ill patients in clinical practice: observational study focus on tigecycline

It is being increasingly recognised by clinicians and scientists that participants in randomised clinical trials (RCTs) of antibiotics of last resort do not represent the patients who will later be treated with these drugs. Data on this subject are limited and have not been investigated systematically. This observational study aimed to examine this hypothesis quantitatively, using the example of tigecycline. To evaluate the influence of recruitment, patients eligible for clinical trials were retrospectively compared with ineligible patients regarding baseline and clinical characteristics as well as outcome parameters, e.g. length of hospital stay, intensive care unit (ICU) stay, ventilation and mortality. The clinical characteristics of 187 patients illustrated differences in the nature and severity of disease, co-morbidities and outcome. Eligible and ineligible patients differed in a number of parameters, e.g. median APACHE II score (15.5 vs. 28.0), number of liver transplantations (5% vs. 18%; P=0.048), septic shock (21% vs. 49%; P=0.001), need for mechanical ventilation (30% vs. 79%; P<0.001), mean length of ICU stay (19.3 days vs. 40.7 days) and death (19% vs. 46%; P=0.001). Critically ill patients were under-represented in clinical trials. Moreover, only a minority of patients in clinical practice (13%) were potentially eligible for a pivotal RCT. The disparities likely result from strict exclusion criteria in RCTs and recruitment bias. These data emphasise the importance of including critically ill patients in RCTs of antibiotics against multiresistant bacteria in order to account for those who will later be treated.