Efficacy and safety of tigecycline for the treatment of severe infectious diseases: an updated meta-analysis of RCTs

Systematic analysis of the adverse effects of commonly used clinical tetracycline drugs based on the FAERS database

BACKGROUND

Tetracyclines are a class of antibacterial drugs commonly used in clinical practice, but there is no systematic analysis of the adverse effects (AEs) of these drugs. We performed such pharmacovigilance analyses using the US Food and Drug Administration Adverse Event Reporting System (FAERS) database to explore tetracycline-related AEs.

RESEARCH DESIGN AND METHODS

We used the pharmacovigilance analysis tool Open Vigil 2.1 to access FAERS data and obtained AE reports from January 2004 to June 2023, including doxycycline, minocycline, tigecycline, omadacycline, sarecycline, and eravacycline as the top suspect drugs. The signal value of the AE of the analyzed drug was calculated by the reporting odds ratio (ROR).

RESULTS

A total of 15,020 cases were identified by analyzing drugs. In terms of adverse signals, doxycycline caused gastrointestinal mucosal necrosis (ROR = 1699.652); minocycline was reported to cause bone hyperpigmentation (ROR = 30976.223); tigecycline is responsible for blood fibrinogen decreased (ROR = 1714.078).

CONCLUSIONS

AE reports of tetracycline drugs varied significantly. We found some AEs not mentioned in the instruction, such as the ototoxicity of tetracyclines. Doxycycline was associated with psychiatric side effects; minocycline presented in thyroid and skin tissue-associated tumors; abnormal signals were detected with eravacycline in the blood system.

Safety profiles of doxycycline, minocycline, and tigecycline in pediatric patients: a real-world pharmacovigilance analysis based on the FAERS database

Introduction

Recently, the rise of antibiotic resistance has prompted a reconsideration of tetracyclines. However, existing studies are inadequate in assessing the pediatric safety of this class of antibiotics. To address the gap, our study aims to comprehensively assess the safety of tetracyclines in children.

Methods

Adverse event (AE) reports from January 2005 to September 2023 were obtained from the U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database, and reporting odds ratio (ROR) was performed to identify potential risk signals in children under 18 years old who were administered any of the three tetracyclines: doxycycline, minocycline, and tigecycline.

Results

A total of 1903 AE cases were included in our study: 782 for doxycycline, 981 for minocycline, and 140 for tigecycline. Doxycycline and tigecycline were predominantly associated with "general disorders and administration site conditions" and "gastrointestinal disorders," while minocycline was more frequently linked to "skin and subcutaneous tissue disorders" and "gastrointestinal disorders." Psychiatric risks predominantly included depression, suicidal ideation, and suicide attempt. In the category of skin and subcutaneous tissues, 30.88% of the minocycline-induced drug reaction with eosinophilia and systemic symptoms (DRESS) cases resulted in death, alongside a high occurrence of co-occurring AEs such as multiple organ dysfunction syndrome, Type 1 Diabetes Mellitus (T1DM), and autoimmune thyroiditis. As for the endocrine system, both doxycycline and minocycline were found to potentially increase the risk of thyroid dysfunction. For children under the age of 8, doxycycline was associated with tooth discoloration (N = 7, ROR = 20.11%, 95% CI: 9.48-42.67), although it remained unclear whether the discoloration was permanent.

Conclusion

Our findings indicated that for pediatric patients, the majority of results were in line with the prescribing information and previous studies, and minocycline tended to cause more frequent and severe AEs than doxycycline. However, it is noteworthy that exceptions were found for psychiatric disorders and thyroid dysfunction associated with doxycycline, which are not mentioned in its FDA prescribing information. Additionally, further safety studies on tigecycline are still needed for children. When prescribing tetracyclines to pediatric patients, a careful risk-benefit assessment is crucial.

Monotherapy vs combination therapy in patients with Klebsiella pneumoniae bloodstream infection: A systematic review and meta-analysis

OBJECTIVE

To determine whether mortality is lower in patients with Klebsiella pneumoniae bloodstream infection (BSI) who receive combination antimicrobial therapy than in those who receive monotherapy.

METHODS

Two authors independently searched for relevant articles in the PubMed, Embase, Web of Science, and Cochrane Library databases through to August 10, 2023. Risk of bias was evaluated using the ROBINS-I tool. Possible sources of heterogeneity were evaluated by meta-regression using a mixed-effects model.

RESULTS

Among 8044 articles screened, there were 23 studies (3443 patients) that were eligible for meta-analysis. Meta-regression analysis identified the proportion of patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) BSI to be a potential source of heterogeneity. Subgroup analysis showed that mortality on monotherapy was significantly higher when the proportion of patients with CRKP BSI was ≥50% (OR 1.75, 95% CI 1.33-2.30) and significantly lower when this proportion was <50% (OR 0.55, 95% CI 0.24-1.24). Overall mortality was significantly higher on tigecycline monotherapy (OR 2.86, 95% CI 1.46-5.59) than on combination therapy containing both these agents. There was a trend in favor of colistin/polymyxin B-containing combination therapy (OR 1.37, 95% CI 0.83-2.28).

CONCLUSIONS

Combination antimicrobial therapy can lower mortality in patients with CRKP but may not show a survival advantage over monotherapy when the proportion of patients with CRKP BSI is <50%. High-quality prospective observational studies are needed because of the high risk of bias and limited data in the studies performed to date.

WHO's essential medicines and AWaRe: recommendations on first- and second-choice antibiotics for empiric treatment of clinical infections

The WHO Model List of Essential Medicines (EML) prioritizes medicines that have significant global public health value. The EML can also deliver important messages on appropriate medicine use. Since 2017, in response to the growing challenge of antimicrobial resistance, antibiotics on the EML have been reviewed and categorized into three groups: Access, Watch, and Reserve, leading to a new categorization called AWaRe. These categories were developed taking into account the impact of different antibiotics and classes on antimicrobial resistance and the implications for their appropriate use. The 2023 AWaRe classification provides empirical guidance on 41 essential antibiotics for over 30 clinical infections targeting both the primary health care and hospital facility setting. A further 257 antibiotics not included on the EML have been allocated an AWaRe group for stewardship and monitoring purposes. This article describes the development of AWaRe, focussing on the clinical evidence base that guided the selection of Access, Watch, or Reserve antibiotics as first and second choices for each infection. The overarching objective was to offer a tool for optimizing the quality of global antibiotic prescribing and reduce inappropriate use by encouraging the use of Access antibiotics (or no antibiotics) where appropriate. This clinical evidence evaluation and subsequent EML recommendations are the basis for the AWaRe antibiotic book and related smartphone applications. By providing guidance on antibiotic prioritization, AWaRe aims to facilitate the revision of national lists of essential medicines, update national prescribing guidelines, and supervise antibiotic use. Adherence to AWaRe would extend the effectiveness of current antibiotics while helping countries expand access to these life-saving medicines for the benefit of current and future patients, health professionals, and the environment.

Co-Occurrence of tet(X4) and blaNDM-5 in Escherichia coli Isolates of Inpatient Origin in Guangzhou, China

Tigecycline, one of the last-resort therapeutic options for complicated infections caused by multidrug-resistant pathogens, especially carbapenem-resistant Enterobacterales and Acinetobacter in recent years. The emergence of antibiotic-resistant bacteria and antibiotic-resistant genes has threatened the effectiveness of antibiotics and public health with the excessive use of antibiotics in clinics. However, the emergence and dissemination of high-level mobile tigecycline-resistance gene tet(X) is challenging for clinical effectiveness of antimicrobial agent. This study aimed to characterize an E. coli strain T43, isolated from an inpatient in a teaching hospital in China. The E. coli T43 was resistant to almost all antimicrobials except colistin and consisted of a 4,774,080 bp chromosome and three plasmids. Plasmids pT43-1 and pT43-2 contained tigecycline-resistance gene tet(X4). Plasmid pT43-1 had a size of 152,423 bp with 51.05% GC content and harbored 151 putative open reading frames. pT43-1 was the largest plasmid in strain T43 and carried numerous resistance genes, especially tigecycline resistance gene tet(X4) and carbapenemase resistance gene blaNDM-5. The tet(X) gene was associated with IS26. Co-occurrence of numerous resistance genes in a single plasmid possibly contributed to the dissemination of these genes under antibiotics stress. It might explain the presence of clinically crucial resistance genes tet(X) and blaNDM-5 in clinics. This study suggested the applicable use of antibiotics and continued surveillance of tet(X) and blaNDM-5 in clinics are imperative.

Tigecycline as salvage treatment of febrile neutropenia in patients with haematological malignancies-a retrospective single-centre analysis of 200 cases

Tigecycline has been used to treat patients with febrile neutropenia (FN). This study aims to analyse the effectiveness of tigecycline as salvage treatment of FN. Patients records from 09/2004 to 04/2019 were reviewed. Cases were eligible if fever persisted/recurred (p/r-FN) after 3 days of second-line treatment with a carbapenem, and were divided into three groups: switch to tigecycline (TGC group), switch to other antibiotics (OAB group), and no switch (W&W group). The primary endpoint was response rate (defervescence for ≥ 7 days or at least until discharge); the key secondary endpoint was 30-day mortality rate. Two hundred cases from 176 patients (median 59 years; 53.5% men) treated were included, mostly acute myeloid leukaemias (61.0%). 45.5% of cases were in the TGC group (in combination with an anti-pseudomonal antibiotic, mostly ceftazidime [95.6%]); 35.5% were in the OAB and 19.0% in the W&W group. There was no significant difference in response rates (TGC, 73.6%; OAB, 62.0%; W&W, 78.9%; p = 0.12) or 30-day mortality rates (TGC, 7.7%; OAB, 7.0%; W&W, 5.3%; p = 0.94). Tigecycline plus an anti-pseudomonal antibiotic does not improve response or 30-day mortality rate compared to other antibiotics in patients with p/r-FN. Also, in some cases, no switch in antibiotics may be necessary at all.

Efficacy and safety of ceftazidime-avibactam versus polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infection: a systematic review and meta-analysis

OBJECTIVES

Carbapenem-resistant Enterobacteriaceae is increasingly recognised as a significant public health concern. Ceftazidime-avibactam (CAZ-AVI) and polymyxins are considered as the last therapeutic options worldwide. This is the first meta-analysis of recently published data to compare the clinical efficacy and safety of CAZ-AVI with polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infections.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase and the Cochrane Library were systematically searched, for publications in any language, from database inception to February 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies comparing the clinical efficacy and safety of CAZ-AVI with polymyxins were included. Mortality, clinical success, microbiological eradication and nephrotoxicity were assessed as the main outcomes.

DATA EXTRACTION AND SYNTHESIS

Literature screening, data extraction and the quality evaluation of studies were conducted by two researchers independently, with disagreements resolved by another researcher. The Newcastle-Ottawa Scale was used to assess the bias risk for the included studies. Review Manager V.5.3 was employed for the meta-analysis.

RESULTS

The meta-analysis included seven retrospective and four prospective cohort studies with 1111 patients enrolled. The CAZ-AVI groups demonstrated a lower 30-day mortality (risk ratio (RR)=0.48, 95% CI of 0.37 to 0.63, I²=10%, p<0.0001) in nine studies with 766 patients; higher clinical success (RR=1.71, 95% CI 1.33 to 2.20, I²=35%, p<0.0001) in four studies with 463 patients; and lower nephrotoxicity in seven studies with 696 patients (RR=0.42, 95% CI 0.23 to 0.77, I²=35%, p<0.05). However, no significant difference in microbiological eradication rates was observed in 249 patients from two studies (RR=1.16, 95% CI 0.97 to 1.39, I²=0, p>0.05).

CONCLUSION

Available evidence suggested that CAZ-AVI treatment held a dominant position with respect to efficacy and safety compared with polymyxins in carbapenem-resistant Enterobacteriaceae infections. However, the analysis included only observational studies, and high-quality, large-scale, multicentre, double-blind randomised controlled trials are needed to confirm the advantage of CAZ-AVI.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Polymyxin B/Tigecycline Combination vs. Polymyxin B or Tigecycline Alone for the Treatment of Hospital-Acquired Pneumonia Caused by Carbapenem-Resistant Enterobacteriaceae or Carbapenem-Resistant Acinetobacter baumannii

Introduction

It is not clear whether polymyxin B/tigecycline (PMB/TGC) combination is better than PMB or TGC alone in the treatment of hospital-acquired pneumonia (HAP) caused by carbapenem-resistant organisms (CROs).

Methods

We conducted a multicenter, retrospective cohort study in patients with HAP caused by CROs. The primary outcome was 28-day mortality, and the secondary outcomes included clinical success and the incidence of acute kidney injury (AKI). Multivariate Cox regression analysis was performed to examine the relationship between antimicrobial treatments and 28-day mortality by adjusting other potential confounding factors.

Results

A total of 364 eligible patients were included in the final analysis, i.e., 99 in the PMB group, 173 in the TGC group, and 92 in the PMB/TGC combination group. The 28-day mortality rate was 28.3% (28/99) in the PMB group, 39.3% (68/173) in the TGC group, and 48.9% (45/92) in the PMB/TGC combination group (p = 0.014). The multivariate Cox regression model showed that there was a statistically significant lower risk of 28-day mortality among participants in the PMB group when compared with the PMB/TGC combination group [hazard ratio (HR) 0.50, 95% confidence interval (CI) 0.31–0.81, p = 0.004] and that participants in the TGC group had a lower risk of 28-day mortality than in the PMB/TGC combination group but without statistical significance. The incidence of AKI in the PMB group (52.5%) and the PMB/TGC combination group (53.3%) was significantly higher than that in the TGC group (33.5%, p = 0.001).

Conclusion

The appropriate PMB/TGC combination was not superior to appropriate PMB therapy in the treatment of HAP caused by carbapenem-resistant Enterobacteriaceae/carbapenem-resistant Acinetobacter baumannii (CRE/CRAB) in terms of 28-day mortality.

Treatment of Hospital-Acquired Infections in Patients with Cirrhosis - New Challenges

Background

Hospital acquired infections (HAI) in the cirrhotic patients contribute to hepatic decompensation. With emergence of bacterial drug resistance, designing the treatment protocol of HA infection has become the foremost challenge.

Purpose

To analyze the resistance pattern of organisms isolated from hospital-acquired (HA) infections and determine appropriate antibiotics treatment protocols for these infections.

Study Design

A prospective hospital based observational study was undertaken.

Patients and Methods

The present study was conducted over 18 months at Kasturba Medical College, Mangalore, Karnataka, India. Patients with suspected HA infections were subjected to clinical, hematological and microbiological evaluation. Antibiotic sensitivity evaluation was undertaken for the bacteria isolated from these patients.

Results

During the study period, 398 patients with cirrhosis were 472 times admitted to the hospital for treatment. Out of these patients, 40 patients were diagnosed with 50 HA infections. Fifty five different organisms were isolated from these infections. It was found that these 55 bacteria isolates comprised 30 (54.54%) gram-negative (GN) and 25 (45.45%) gram-positive (GP) bacteria. Quite seriously, extended-spectrum beta-lactamase (ESBL) producers and methicillin-resistant Staphylococcus aureus (MRSA) were detected in 40% and 58% of GN and GP infections respectively. A total of 36 (65.4%) and (14.5%) 8 out of 55 isolated organisms exhibited multi–drug resistance (MDR) and extensive drug resistance (XDR) behavior, respectively.

Conclusion

Cirrhosis patients with HA infection possess higher prevalence of MDR and XDR infections. In such sick patients, cephalosporin and quinolones are not the appropriate empirical antibiotics. Herein, we propose a tigecycline with carbapenem like meropenem and vancomycin based empirical antibiotics protocol to be prescribed for such patients. De-escalation is advised after the culture sensitivity report is obtained.

In vitro and in vivo Activity of Combinations of Polymyxin B with Other Antimicrobials Against Carbapenem-Resistant Acinetobacter baumannii

Purpose

To study the in vitro and in vivo antibacterial activities of polymyxin B (PB) and other five antimicrobial agents, including imipenem (IMP), meropenem (MEM), tigecycline (TGC), sulbactam (SUL), and rifampicin (RIF), alone or in combination against carbapenem-resistant Acinetobacter baumannii (CRAB).

Methods

Microbroth dilution method was used to determine the minimum inhibitory concentration (MIC) of ten strains of CRAB against six antibacterial drugs, and the checkerboard method was used to determine the fractional inhibitory concentration index (FICI). A mouse pneumonia model was established by intranasal instillation of Ab5075 to evaluate the antibacterial activity in vivo.

Results

The resistance rate of ten CRAB strains to IMP, MEM, and SUL was 100%, that to PB and TGC was 0%, and that to RIF was 20%. When PB was used in combination with the other five antibiotics in vitro, it mainly showed synergistic and additive effects on CRAB. The synergistic effect of PB and RIF was maximal, followed by MEM and IMP but was weak with SUL and TGC. In vivo, compared to the model group (untreated with antibiotics), treatment group (six antibiotics alone and PB combined with the other five antibiotics) reduced the bacterial load in the lung tissue and the serum inflammatory factors (IL-1β, IL-6, and TNF-α). The bacterial load and the inflammatory factors of the combined group decreased significantly than that of the single group (P<0.05). The IL-6 and TNF-α values of the PB combined with the RIF group were significantly lower than the two drugs used individually.

Conclusion

The combination of PB and IMP, MEM, and RIF exerted robust in vitro synergistic effects on CRAB isolates. The combination of PB and the other five antimicrobial agents had a better effect in the mouse pneumonia model than single agent, while the combination of PB and RIF had the best effect.

Antibiotic Treatment of Pulmonary Infections: An Umbrella Review and Evidence Map

Background: Considering the global burden of pulmonary infections, there is an urgent need for optimal empirical antimicrobial therapy strategies for pulmonary infections, which should rely on reliable evidence. Therefore, we aim to investigate the optimal treatment options for pulmonary infections in adults and assess the strength of that evidence. Methods: We searched PubMed, Embase, the Cochrane Library, and China Biology Medicine disc to identify systematic reviews and meta-analyses of randomized controlled trials (RCTs) focusing on antimicrobial treatments for pulmonary infections. The outcomes of the included meta-analyses should include all-cause mortality or clinical treatment success. For each meta-analysis, we estimated relative risk (RR) with 95% CI. We also created an evidence map to show the efficacy of each antimicrobial treatment strategy and the certainty of the evidence. Results: Twenty-six meta-analyses and two new RCTs were included that contained 31 types of antimicrobial therapy strategies. We found that carbapenems were related to lower mortality than other β-lactams or fluoroquinolones alone or in combination with aminoglycosides for HAP patients (RR 0.76, 95% CI: 0.58-0.99). There was no statistical difference in all-cause mortality between the other antimicrobial therapy strategies. As for clinical cure, treatment with fluoroquinolones was associated with better success versus macrolides or β-lactams alone for CAP patients in both the intention-to-treat (ITT) population (RR 1.22, 95% CI: 1.02-1.47) and clinically evaluable (CE) population (RR 1.37, 95% CI: 1.11-1.68). Treatment with carbapenems showed a better clinical cure over non-carbapenems for VAP patients (RR 1.21, 95% CI: 1.05-1.4). Adjunctive inhaled antibiotics compared with intravenous antibiotics alone showed a benefit for VAP (RR 1.2, 95% CI: 1.05-1.35). In addition, adjunctive nebulized aminoglycoside for nosocomial pneumonia was associated with a higher cure rate versus intravenous antibiotics alone in the ITT population (RR 1.28, 95% CI: 1.04-1.57), while no statistical difference in clinical cure was observed between other intervention groups. Conclusions: We cannot evaluate which antibiotic is the best choice for the treatment of pulmonary infection. Carbapenems or adjunctive inhaled antibiotics showed a reasonable choice for HAP or VAP. However, we do not find a statistical difference between most antimicrobial therapy strategies for CAP patients.

Tigecycline in the Treatment of Ventilator-Associated Pneumonia Due to Stenotrophomonas maltophilia: A Multicenter Retrospective Cohort Study

Introduction

Tigecycline is a potential alternative to trimethoprim–sulfamethoxazole in treating Stenotrophomonas maltophilia infections due to its potent in vitro antimicrobial activity. Clinical evidence regarding the use of tigecycline in the treatment of S. maltophilia infections is scarce. In this study, we assessed the efficacy of tigecycline treating ventilator-associated pneumonia (VAP) due to S. maltophilia in comparison with fluoroquinolones.

Methods

This is a multicenter retrospective cohort study of patients admitted between January 2017 and December 2020 with the diagnosis of VAP caused by S. maltophilia receiving either tigecycline or fluoroquinolones as the definitive therapy ≥ 48 h. Clinical outcomes including 28-day mortality, clinical cure and microbiological cure were analyzed.

Results

Of 82 patients with S. maltophilia VAP included, 46 received tigecycline, and 36 received fluoroquinolones; 70.7% of patients had polymicrobial pneumonia, and the appropriate empiric therapy was applied to only 14.6% of patients. The overall 28-day mortality was 39%. Compared with patients receiving fluoroquinolones, tigecycline therapy resulted in worse clinical cure (32.6% vs. 63.9%, p = 0.009) and microbiological cure (28.6% vs. 59.1%, p = 0.045), while there was no statistical difference between 28-day mortality (47.8% vs. 27.8%, p = 0.105) in the two groups. Similar results were also shown in the inverse probability of treatment weighted univariable regression model and multivariable regression model.

Conclusions

The standard dose of tigecycline therapy was associated with a lower clinical and microbiological cure rate but not associated with an increased 28-day mortality in patients with S. maltophilia VAP compared with fluoroquinolones. Considering the unfavorable clinical outcomes, we therefore recommend against using the standard dose of tigecycline in treating S. maltophilia VAP unless new clinical evidence emerges.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00516-5.

Population pharmacokinetics and exposure-response analysis of tigecycline in patients with hospital-acquired pneumonia

BACKGROUND

Tigecycline has been widely used to treat hospital-acquired pneumonia (HAP) off-label since it is effective against a wide range of multidrug-resistant bacteria. However, no recommended dosage for this indication has been evaluated, resulting in possible inadequate treatment.

AIMS

The aims of this study are to establish the population pharmacokinetic (PPK) model of tigecycline in Chinese patients with HAP, as well as to evaluate the exposure-response relationship for the treatment of HAP with multidrug-resistant gram-negative bacteria.

METHODS

A PPK analysis of tigecycline was conducted on pooled data from 328 blood samples obtained from 89 patients with HAP. Tigecycline plasma concentrations were measured by a two-dimensional liquid chromatographic system and the data were analysed using Phoenix NLMETM software. Exposure-response analyses for efficacy were performed based on the data from 79 HAP patients with multidrug-resistant gram-negative infections. Classification and regression tree and logistic regression analyses were employed to identify which pharmacokinetic-pharmacodynamic (PK-PD) indices and magnitudes were the significant predictors of tigecycline efficacy.

RESULTS

A two-compartment model with zero-order absorption and first-order elimination adequately described the data. A larger body weight was associated with increased central volume of distribution and clearance (P < .005), and increased age, baseline creatinine concentration and aspertate aminotransferase were associated with decreased clearance (P < .005). The AUC_0-12h  × V/MIC ratio, APACHEII score and combined Pseudomonas aeruginosa infection are the strong predictors for tigecycline clinical response. Classification and regression tree analyses indicated that the combination of APACHEII score < 24 and AUC_0-12h  × V/MIC ratio ≥ 100 was associated with clinical success.

CONCLUSIONS

The proposed PPK model may serve as the basis for estimating tigecycline exposure for PK-PD analyses, and the PK-PD index and magnitude found in this study could be used for designing proper dosage regimens of tigecycline.

Synergistic Antibacterial Effect of Casein-AgNPs Combined with Tigecycline against Acinetobacter baumannii

Acinetobacter baumannii (A. baumannii) is a common and challenging pathogen of nosocomial infections, due to its ability to survive on inanimate objects, desiccation tolerance, and resistance to disinfectants. In this study, we investigated an antibacterial strategy to combat A. baumannii via the combination of antibiotics and silver protein. This strategy used a functional platform consisting of silver nanoparticles (AgNPs) resurrected from silver-based calcium thiophosphate (SSCP) through casein and arginine. Then, the silver protein was combined with tigecycline, the first drug in glycylcycline antibiotic, to synergistically inhibit the viability of A. baumannii. The synergistic antibacterial activity was confirmed by the 96-well checkerboard method to determine their minimum inhibitory concentrations (MIC) and calculated for the combination index (CI). The MIC of the combination of silver protein and tigecycline (0.31 mg/mL, 0.16 µg/mL) was significantly lower than that of the individual MIC, and the CI was 0.59, which indicates a synergistic effect. Consequently, we integrated the detailed synergistic antibacterial properties when silver protein was combined with tigecycline. The result could make for a promising approach for the treatment of A. baumannii.

Tigecycline antibacterial activity, clinical effectiveness, and mechanisms and epidemiology of resistance: narrative review

Tigecycline is unique glycylcycline class of semisynthetic antimicrobial agents developed for the treatment of polymicrobial infections caused by multidrug-resistant Gram-positive and Gram-negative pathogens. Tigecycline evades the main tetracycline resistance genetic mechanisms, such as tetracycline-specific efflux pump acquisition and ribosomal protection, via the addition of a glycyclamide moiety to the 9-position of minocycline. The use of the parenteral form of tigecycline is approved for complicated skin and skin structure infections (excluding diabetes foot infection), complicated intra-abdominal infections, and community-acquired bacterial pneumonia in adults. New evidence also suggests the effectiveness of tigecycline for the treatment of severe Clostridioides difficile infections. Tigecycline showed in vitro susceptibility to Coxiella spp., Rickettsia spp., and multidrug-resistant Neisseria gonnorrhoeae strains which indicate the possible use of tigecycline in the treatment of infections caused by these pathogens. Except for intrinsic, or often reported resistance in some Gram-negatives, tigecycline is effective against a wide range of multidrug-resistant nosocomial pathogens. Herein, we summarize the currently available data on tigecycline pharmacokinetics and pharmacodynamics, its mechanism of action, the epidemiology of tigecycline resistance, and its clinical effectiveness.

Effect of pharmacokinetic/pharmacodynamic ratio on tigecycline clinical response and toxicity in critically ill patients with multidrug-resistant Gram-negative infections

Introduction:

The information about the pharmacokinetics and optimal dose of tigecycline in critically ill patients with severe underlying diseases is limited and controversial. In this study, we evaluate the pharmacokinetic parameters of tigecycline in critically ill patients with multidrug-resistant Gram-negative infection and explore the association between the pharmacokinetic/pharmacodynamic ratio and treatment response.

Methods:

A prospective study was designed including critically ill patients treated with tigecycline for multidrug-resistant Gram-negative infections. Blood samples were collected at day 3–5 of treatment, and pharmacokinetics parameters were evaluated using NONMEM^® software. Relationship between area under the free concentration–time curve and minimum inhibitory concentration ratio (fAUC/MIC) and treatment failure was evaluated. Association between tigecycline fAUC and hepatobiliary toxicity was also investigated.

Results:

Twenty-five critically ill patients were included in the study. In the pharmacokinetic model, weight and total bilirubin level were found to be significant predictors of tigecycline clearance. Fifteen (60.0%) patients achieved an fAUC/MIC ratio >4.5, seven (28.0%) an fAUC/MIC > 6.96 and only three (12.0%) an fAUC/MIC > 17.9. No differences in fAUC/MIC ratio were obtained between those patients with and without clinical failure (5.28 (IC95%: 2.57–7.94) vs 8.71 (3.57–13.84)). fAUC values were higher in those patients who suffered hepatobiliary disorders (7.63 (3.93–11.34) vs 17.63 (7.85–26.28) mg/L/h).

Conclusion:

An important percentage of critically ill patients with multidrug-resistant Gram-negative infection treated with tigecycline do not achieve an appropriate pharmacokinetic/pharmacodynamic value. Tigecycline fAUC seems to be associated with hepatobiliary disorders in this study population. The effect of fAUC/MIC ratio on clinical response remains unclear.

Effectiveness and Safety of High Dose Tigecycline for the Treatment of Severe Infections: A Systematic Review and Meta-Analysis

BACKGROUND

Studies assessing the effect of high dose tigecycline on severe infections are limited and remain controversial.

OBJECTIVES

To assess systematically the effectiveness and safety of high dose tigecycline in the treatment of severe infections.

METHODS

Pubmed, Web of Science, Embase, MEDLINE, Cochrane Library and ClinicalTrials were searched up to February 20, 2019 for studies that compared the effectiveness and safety of high dose tigecycline with standard dose tigecycline or other non-tigecycline-containing regimens in the treatment of severe infections. Rates for all-cause mortality, clinical cure, microbiological eradication and adverse events were analysed.

RESULTS

Ten studies with 593 patients were included. The results indicated that using high dose tigecycline resulted in better outcomes compared with controls with lower all-cause mortality (OR 0.44, 95% CI 0.30-0.66, p < 0.0001), higher clinical cure (OR 3.43, 95% CI 2.09-5.63, p < 0.00001), higher microbiological eradication (OR 2.25, 95% CI 1.44-3.50, p = 0.0003), and without increasing adverse events rates. Subgroup analysis showed that high dose tigecycline reduced all-cause mortality in nosocomial acquired pneumonia (OR 0.39, 95% CI 0.22-0.70, p = 0.002), bloodstream infections (OR 0.19, 95% CI 0.06-0.58, p = 0.004) and mixed infections (OR 0.20, 95% CI 0.07-0.59, p = 0.003), with no statistical differences in complicated intra-abdominal infections (OR 2.04, 95% CI 0.80-5.23, p = 0.14). In carbapenem-resistant pathogens, the microbiological eradication rate in those given high dose tigecycline did not differ from controls (OR 1.07, 95% CI 0.44-2.60, p = 0.87), although mortality was reduced (OR 0.20, 95% CI 0.09-0.45, p = 0.0001). The main limitation of the review is that most of the included studies are observational studies with small sample sizes and high risks of bias.

CONCLUSIONS

High dose tigecycline treatment is effective and safe for severe infections owing to its lower all-cause mortality, higher clinical cure, microbiological eradication and comparable adverse events. However, as a result of the high risks of bias of the included studies, well-designed randomised clinical trials are warranted to establish the effectiveness and safety of high dose tigecycline compared with standard dose tigecycline and other commonly used antibiotics.

Tigecycline versus INR increase; more than expected?

Objectives: The aim of the study was to investigate the frequency of tigecycline-associated INR abnormality.Methods: Patients who were hospitalized between June and September 2016 and treated with tigecycline including therapy were extracted from hospital database and retrospectively reviewed. INR values at the beginning and end of treatment were compared.Results: A total of 79 patients who received tigecycline were identified by analyzing the hospital database. Nineteen patients were excluded from the study since INR was not measured at the beginning and/or end of treatment. In 55 of the 60 patients, INR levels were within normal limits (0.9-1.2) at the beginning of treatment while 19 of these 55 (34,5%) had prolonged INR after treatment. Prolongation was found to be mild (1.01-1.25 x ULN-upper limit of normal) in 12 of 19 patients, moderate (1.26-1.5 x ULN) in six and severe (1.51-3.0 x ULN) in one. In 10 of 19 patients, tigecycline was stopped, and the INR values normalized. There was no difference in INR abnormality rate between tigecycline monotherapy versus combination therapy receiving cases (19/27-33% vs. 10/33-30% p:1).Conclusion: These data show that INR prolongation may develop as common as 34.6% during tigecycline therapy. Regular INR follow-up may be beneficial in cases receiving tigecycline.

Carbapenem-Sparing Strategies for ESBL Producers: When and How

Extended spectrum β-lactamase (ESBL)-producing bacteria are prevalent worldwide and correlated with hospital infections, but they have been evolving as an increasing cause of community acquired infections. The spread of ESBL constitutes a major threat for public health, and infections with ESBL-producing organisms have been associated with poor outcomes. Established therapeutic options for severe infections caused by ESBL-producing organisms are considered the carbapenems. However, under the pressure of carbapenem overuse and the emergence of resistance, carbapenem-sparing strategies have been implemented. The administration of carbapenem-sparing antibiotics for the treatment of ESBL infections has yielded conflicting results. Herein, the current available knowledge regarding carbapenem-sparing strategies for ESBL producers is reviewed, and the optimal conditions for the "when and how" of carbapenem-sparing agents is discussed. An important point of the review focuses on piperacillin-tazobactam as the agent arousing the most debate. The most available data regarding non-carbapenem β-lactams (i.e., ceftolozane-tazobactam, ceftazidime-avibactam, temocillin, cephamycins and cefepime) are also thoroughly presented as well as non β-lactams (i.e., aminoglycosides, quinolones, tigecycline, eravacycline and fosfomycin).

Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most successful modern pathogens. The same organism that lives as a commensal and is transmitted in both health-care and community settings is also a leading cause of bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and hospital-acquired infections. Genetically diverse, the epidemiology of MRSA is primarily characterized by the serial emergence of epidemic strains. Although its incidence has recently declined in some regions, MRSA still poses a formidable clinical threat, with persistently high morbidity and mortality. Successful treatment remains challenging and requires the evaluation of both novel antimicrobials and adjunctive aspects of care, such as infectious disease consultation, echocardiography and source control. In this Review, we provide an overview of basic and clinical MRSA research and summarize the expansive body of literature on the epidemiology, transmission, genetic diversity, evolution, surveillance and treatment of MRSA.

Colistin-sparing approaches with newer antimicrobials to treat carbapenem-resistant organisms: Current evidence and future prospects

Antimicrobial resistance is on the rise across the globe. Increasing incidence of infections due to carbapenem resistance organisms is becoming difficult to treat, due to the limited availability of therapeutic agents. Very few agents such as colistin, fosfomycin, tigecycline and minocycline are widely used, despite its toxicity. However, with the availability of novel antimicrobials, beta-lactam/beta-lactamase inhibitor-based and non-beta-lactam-based agents could be of great relief. This review covers three important aspects which include (i) current management of carbapenem-resistant infections, (ii) determination of specific types of carbapenemases produced by multidrug-resistant and extensively drug-resistant Gram-negative pathogens and (iii) the currently available novel beta-lactam/beta-lactamase inhibitors and non-beta-lactam-based agents' laboratory findings, clinical outcome and implications.

Acinetobacter Pneumonia: Improving Outcomes With Early Identification and Appropriate Therapy

In an era of increasing antimicrobial resistance, Acinetobacter distinguishes itself as one of the most resistant Gram-negative bacteria responsible for significant morbidity and mortality. New solutions are needed to combat the detrimental effects of increasing rates of antimicrobial resistance. Using empiric broad-spectrum antibiotics in patients deemed at risk for infections caused by multidrug-resistant pathogens may protect against attributable mortality, but this temporary solution furthers the risk of antimicrobial resistance. In this article we will review relevant strategies to aid with early identification and appropriate treatment of Acinetobacter pneumonia while preserving antibiotic susceptibility.

Carbapenemases in Enterobacteriaceae: Detection and Antimicrobial Therapy

Carbapenem-resistant Enterobacteriaceae (CRE) have spread rapidly around the world in the past few years, posing great challenges to human health. The plasmid-mediated horizontal transmission of carbapenem-resistance genes is the main cause of the surge in the prevalence of CRE. Therefore, the timely and accurate detection of CRE, especially carbapenemase-producing Enterobacteriaceae, is very important for the clinical prevention and treatment of these infections. A variety of methods for the rapid detection of CRE phenotypes and genotypes have been developed for use in clinical microbiology laboratories. To overcome the lack of efficient antibiotics, CRE infections are often treated with combination therapies. Moreover, novel drugs and emerging strategies appeared successively and in various stages of development. In this article, we summarized the global distribution of various carbapenemases. And we focused on summarizing and comparing the advantages and limitations of the detection methods and the therapeutic strategies of CRE primarily.

Management of ventilator-associated pneumonia (VAP) caused by resistant gram-negative bacteria: which is the best strategy to treat?

Introduction: Treatment of ventilator-associated pneumonia (VAP) is a major challenge. The increase in multi-drug resistant bacteria has not been accompanied by the validation of new drugs, or by any new antimicrobial strategies to exploit the available agents. VAP due to Gram-negative bacteria has increased mortality, both due to the resistant pathogens themselves and due to inappropriate treatment. Local epidemiology, patients' characteristics and clinical responses provide the most important information for therapeutic decision-making. Moreover, data on VAP therapy due to resistant bacteria are lacking, and the choice of treatment is often based on clinical practice and individual experience. Areas covered: This review summarizes the strategies available for treating the three most prevalent resistant Gram-negative organisms causing VAP: Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae. The review covers the results of a Pubmed search, clinical practice guidelines and reviews, and the authors' experience. Expert opinion: The existing evidence focuses on bloodstream infections or other sites rather than pneumonia and there are no recommendations for the treatment of VAP by multi-drug resistant Gram-negative bacteria, especially for combination regimens. The approval of new drugs is needed to provide effective and safe alternatives for treating carbapenemase-producing strains. Precision medicine and personalized approach are also fundamental in future research.

The Role of Minocycline in the Treatment of Nosocomial Infections Caused by Multidrug, Extensively Drug and Pandrug Resistant Acinetobacter baumannii: A Systematic Review of Clinical Evidence

Treatment options for multidrug resistant Acinetobacter baumannii strains (MDR-AB) are limited. Minocycline has been used alone or in combination in the treatment of infections associated with AB. A systematic review of the clinical use of minocycline in nosocomial infections associated with MDR-AB was performed according to the PRISMA-P guidelines. PubMed-Medline, Scopus and Web of Science ^TM databases were searched from their inception until March 2019. Additional Google Scholar free searches were performed. Out of 2990 articles, 10 clinical studies (9 retrospective case series and 1 prospective single center trial) met the eligibility criteria. In total, 223 out of 268 (83.2%) evaluated patients received a minocycline-based regimen; and 200 out of 218 (91.7%) patients with available data received minocycline as part of a combination antimicrobial regimen (most frequently colistin or carbapenems). Pneumonia was the most common infection type in the 268 cases (80.6% with 50.4% ventilator-associated pneumonia). The clinical and microbiological success rates following minocycline treatment were 72.6% and 60.2%, respectively. Mortality was 20.9% among 167 patients with relevant data. In this systematic review, minocycline demonstrated promising activity against MDR-AB isolates. This review sets the ground for further studies exploring the role of minocycline in the treatment of MDR-AB associated infections.

Current options for the treatment of infections due to extended-spectrum beta-lactamase-producing Enterobacteriaceae in different groups of patients

BACKGROUND

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are a frequent cause of invasive infections worldwide. Carbapenems are nowadays the most used drugs to treat these infections. However, due to the increasing rates of resistance to these antimicrobials, carbapenem-sparing alternatives are being investigated.

OBJECTIVES AND SOURCES

The aim of this narrative literature review is to summarize the published information on the currently available antibiotics for the treatment of ESBL-E infections, providing specific information on three subgroups of patients: Group 1, patients with severe infections or infections from high-risk sources or in severely immunocompromised patients; Group 2, patients with non-severe infections from intermediate-risk source; and Group 3, patients with non-severe urinary tract infection.

CONTENT AND IMPLICATIONS

For patients in Group 1, the current data would support the use of carbapenems. For milder infections, however, particularly urinary tract infections, other non-carbapenem antibiotics can be considered in selected cases, including beta-lactam/beta-lactam inhibitor combinations, cephamycins, temocillin and aminoglycosides. While specific studies should be performed in these situations, individualized decisions may be taken in order to avoid overuse of carbapenems.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Pharmacokinetic/Pharmacodynamic Evaluation of a Novel Aminomethylcycline Antibiotic, KBP-7072, in the Neutropenic Murine Pneumonia Model against Staphylococcus aureus and Streptococcus pneumoniae

KBP-7072 is a novel aminomethylcycline antibiotic in clinical development for community-acquired pneumonia. The goal of present studies was to determine which pharmacokinetic/pharmacodynamic (PK/PD) parameter magnitude correlated with efficacy in the murine pneumonia infection model against Staphylococcus aureus and Streptococcus pneumoniae KBP-7072 pharmacokinetic measurements were performed in plasma and epithelial lining fluid (ELF) at 4-fold-increasing doses from 1 to 256 mg/kg of body weight subcutaneously. Pharmacokinetic parameters were calculated using a noncompartmental model and were linear over the dose range. Penetration into ELF ranged from 82% to 238% comparing ELF drug concentrations to plasma free drug concentrations. Twenty-four-hour dose-ranging efficacy studies were then performed in the neutropenic murine pneumonia model against 5 S. aureus (3 methicillin-resistant and 2 methicillin-susceptible) and 6 S. pneumoniae (2 Tet^r and 2 Pen^r) strains. KBP-7072 demonstrated potent in vivo activity resulting in a 3- to 5-log₁₀ kill in CFU burden compared to the start of therapy for all strains. The PK/PD index area under the concentration-time curve (AUC)/MIC corelated well with efficacy (R ², 0.80 to 0.89). Net stasis was achieved at plasma 24-h free drug AUC/MIC values of 1.13 and 1.41 (24-h ELF AUC/MIC values of 2.01 and 2.50) for S. aureus and S. pneumoniae, respectively. A 1-log₁₀ kill was achieved at 24-h plasma AUC/MIC values of 2.59 and 5.67 (24-h ELF AUC/MIC values of 4.22 and 10.08) for S. aureus and S. pneumoniae, respectively. A 2-log₁₀ kill was achieved at 24-h plasma AUC/MIC values of 7.16 and 31.14 (24-h ELF AUC/MIC values of 8.37 and 42.92) for S. aureus and S. pneumoniae, respectively. The results of these experiments will aid in the rational design of dose-finding studies for KBP-7072 in patients with community-acquired bacterial pneumonia (CAP).

Current trends in the treatment of pneumonia due to multidrug-resistant Gram-negative bacteria

Pneumonia is one of the most common infections worldwide. Morbidity, mortality, and healthcare costs increase substantially when pneumonia is caused by multidrug-resistant Gram-negative bacteria (MDR-GNB). The ongoing spread of antimicrobial resistance has made treating MDR-GNB pneumonia increasingly difficult. Fortunately, there have been some recent additions to our antibiotic armamentarium in the US and Europe for MDR-GNB, along with several agents that are in advanced stages of development. In this article, we review the risk factors for and current management of MDR-GNB pneumonia as well as novel agents with activity against these important and challenging pathogens.

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.

Tigecycline salvage therapy for critically ill children with multidrug-resistant/extensively drug-resistant infections after surgery

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of salvage therapy of tigecycline in critically ill children with infections caused by multidrug-resistant (MDR)/extensively drug-resistant (XDR) bacteria after surgery.

METHODS

A retrospective chart review was performed of critically ill children after surgery who had received tigecycline for ≥3days between June 2012 and May 2016 in the surgical intensive care unit of a tertiary level children's hospital.

RESULTS

Of 6442 consecutive children admitted after surgery, a total of 22 were enrolled. They had a median age of 7.5 months (interquartile range (IQR), 6 months to 4 years) and a median weight of 7.3kg (IQR, 5.1-12.5kg). Patients received tigecycline for a median 17days (IQR, 12-20 days). The median intensive care unit stay was 56days (IQR, 38-61 days) and median hospital stay was 78days (IQR, 61-94 days). Tigecycline was prescribed as culture-directed therapy in 91% of patients and as empirical therapy in 9%. Clinical success was reported in 86% of the patients. The all-cause mortality in this cohort was 18%. No serious adverse effects of tigecycline were detected in these patients.

CONCLUSIONS

Tigecycline salvage therapy was successful in 86% of critically ill pediatric patients with MDR/XDR infections after surgery, with no severe adverse effects.

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

High-dose tigecycline for the treatment of nosocomial carbapenem-resistant Klebsiella pneumoniae bloodstream infections: A retrospective cohort study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infection (BSI) has become increasingly frequent threat recently, especially in the intensive care unit (ICU). High-dose tigecycline (TGC) regimen is proposed due to the limitation of treatment options. We investigated the efficacy and safety of high-dose TGC combination regimens for treating CRKP BSI. Furthermore, the risk factors for mortality were also determined.This was a single center retrospective cohort study conducted from 2014 to 2016. A total of 40 patients with nosocomial CRKP BSI admitted to the ICU were included; they were classified into two groups according to the treatment regimens with high-dose TGC (HD group) or not (non-HD group). In-hospital mortality rates and microbiologic responses from both groups were reviewed and compared. Besides, the survival and non-survival groups were compared to identify the risk factors of mortality.Twenty-three patients constituted the HD group (high-dosage TGC regimen was administered as 200 mg loading dose followed by 100 mg every 12 h) and 17 patients constituted the non-HD group (standard dose TGC therapy as 100 mg loading dose followed by 50 mg every 12 h and other antibiotics). The in-hospital mortality was 52.2% in the HD group and 76.5% in the non-HD group (P = .117). The Kaplan-Meier test showed significantly longer survival times in the HD group (mean: 83 days vs 28 days; P = .027). Microbiological eradication was observed in 13 patients (56.5%) in the HD group and 6 patients (36.3%) in the non-HD group (P = .184). A smaller fraction of patients in the HD group were subjected to vasoactive therapy (52.2% vs 88.2%; P = .016) compared to the non-HD group. There was no significant difference in the manifestation of adverse effects between the two groups. In the multivariate analysis, multiple organ dysfunction syndrome (MODS), vasoactive therapy, and exposure to carbapenems were regarded as the independent predictors of mortality.A therapeutic regimen consisting of a high dose of TGC was associated with significantly longer survival time and numerically lower mortality in CRKP BSI. Adverse events were not increased with the double dose therapy.

Antimicrobials for the treatment of drug-resistant Acinetobacter baumannii pneumonia in critically ill patients: a systemic review and Bayesian network meta-analysis

BACKGROUND

An optimal therapy for the treatment of pneumonia caused by drug-resistant Acinetobacter baumannii remains unclear. This study aims to compare various antimicrobial strategies and to determine the most effective therapy for pneumonia using a network meta-analysis.

METHODS

Systematic search and quality assessment were performed to select eligible studies reporting one of the following outcomes: all-cause mortality, clinical cure, and microbiological eradication. The primary outcome was all-cause mortality. A network meta-analysis was conducted with a Bayesian approach. Antimicrobial treatments were ranked based on surface under the cumulative ranking curve (SUCRA) value along with estimated median outcome rate and corresponding 95% credible intervals (CrIs). Two treatments were considered significantly different if a posterior probability of superiority (P) was greater than 97.5%.

RESULTS

Twenty-three studies evaluating 15 antimicrobial treatments were included. Intravenous colistin monotherapy (IV COL) was selected as a common comparator, serving as a bridge for developing the network. Five treatments ranked higher than IV COL (SUCRA, 57.1%; median all-cause mortality 0.45, 95% CrI 0.41-0.48) for reducing all-cause mortality: sulbactam monotherapy (SUL, 100.0%; 0.18, 0.04-0.42), high-dose SUL (HD SUL, 85.7%; 0.31, 0.07-0.71), fosfomycin plus IV COL (FOS + IV COL, 78.6%; 0.34, 0.19-0.54), inhaled COL plus IV COL (IH COL + IV COL, 71.4%; 0.39, 0.32-0.46), and high-dose tigecycline (HD TIG, 71.4%; 0.39, 0.16-0.67). Those five treatments also ranked higher than IV COL (SUCRA, 45.5%) for improving clinical cure (72.7%, 72.7%, 63.6%, 81.8%, and 90.9%, respectively). Among the five treatments, SUL (P = 98.1%) and IH COL + IV COL (P = 99.9%) were significantly superior to IV COL for patient survival and clinical cure, respectively. In terms of microbiological eradication, FOS + IV COL (P = 99.8%) and SUL (P = 98.9%) were significantly superior to IV COL.

CONCLUSIONS

This Bayesian network meta-analysis demonstrated the comparative effectiveness of fifteen antimicrobial treatments for drug-resistant A. baumannii pneumonia in critically ill patients. For survival benefit, SUL appears to be the best treatment followed by HD SUL, FOS + IV COL, IH COL + IV COL, HD TIG, and IV COL therapy, in numerical order.

Managing the oncologic patient with suspected pneumonia in the intensive care unit

INTRODUCTION

Solid cancer patients are frequently admitted in intensive care units for critical events. Improving survival rates in this setting is considered an achievable goal today. Respiratory failure is the main reason for admission, representing a primary target for research.

AREAS COVERED

This review presents a diagnostic and therapeutic algorithm for pneumonia and other severe respiratory events in the solid cancer population. It aims to increase awareness of the risk factors and the different etiologies in this changing scenario in which neutropenia no longer seems to be a decisive factor in poor outcome. Bacterial pneumonia is the leading cause, but opportunistic diseases and non-infectious etiologies, especially unexpected adverse effects of radiation, biological drugs and monoclonal antibodies, are becoming increasingly frequent. Options for respiratory support and diagnostics are discussed and indications for antibiotics in the management of pneumonia are detailed. Expert commentary: Prompt initiation of critical care to facilitate optimal decision-making in the management of respiratory failure, early etiological assessment and appropriate antibiotic therapy are cornerstones in management of severe pneumonia in oncologic patients.

Resistance in In Vitro Selected Tigecycline-Resistant Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Is Driven by Mutations in mepR and mepA Genes

A tigecycline-susceptible (TGC-S) Sequence Type (ST) 5 clinical methicillin-resistant Staphylococcus aureus (MRSA) strain was cultured in escalating levels of tigecycline, yielding mutants eightfold more resistant. Their genomes were sequenced to identify genetic alterations, resulting in resistance. Alterations in rpsJ, commonly related to tigecycline resistance, were also investigated. Tigecycline resistance was mediated by loss-of-function mutations in the transcriptional repressor mepR, resulting in derepression of the efflux pump mepA. Increased levels of resistance were obtained by successive mutations in mepA itself. No alterations in RpsJ were observed in selected strains, but we observed a K57M substitution, previously correlated with resistance, among TGC-S clinical strains. Thus, the pathway to tigecycline resistance in CC5 MRSA in vitro appears to be derepression of mep operon as the result of mepR loss-of-function mutation, followed by alterations in MepA efflux pump. This shows that other evolutionary pathways, besides mutation of rpsJ, are available for evolving tigecycline resistance in CC5 MRSA.

New agents for the treatment of infections with Gram-negative bacteria: restoring the miracle or false dawn?

BACKGROUND

Antibiotic resistance in Gram-negative resistance has developed without a commensurate response in the successful development of antibiotic agents, though recent progress has been made.

AIMS

This review aims to provide a summary of the existing evidence on efficacy, spectrum of activity and the development of resistance of new agents that have been licensed or have completed advanced clinical trials and that possess activity against resistant Gram-negative organisms.

SOURCES

A review of the published literature via MEDLINE database was performed. Relevant clinical trials were identified with the aid of the clinicaltrials.gov registry. Further data were ascertained from review of abstracts from recent international meetings and pharmaceutical companies.

CONTENT

Data on the mechanism of action, microbiological spectrum, clinical efficacy and development of resistance are reported for new agents that have activity against Gram-negative organisms. This includes the β-lactam/β-lactamase inhibitor combinations ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam, meropenem/vaborbactam and aztreonam/avibactam; cefiderocol, a siderophore cephalosporin; plazomicin and eravacycline.

IMPLICATIONS

The development of new agents with activity against multidrug-resistant Gram-negative pathogens has provided important therapeutic options for clinicians. Polymyxins appear to have been supplanted by new agents as first-line therapy for Klebsiella pneumoniae carbapenemase producers. Cefiderocol and ceftazidime/avibactam/aztreonam are promising options for metallo-β-lactamase producers, and cefiderocol and ceftolozane/tazobactam for multiply resistant Pseudomonas aeruginosa, but definitive data showing clinical efficacy is as yet lacking. Reports of the development of resistance early after the release and use of new agents is of concern. Orally administered options and agents active effective against Acinetobacter baumannii are under-represented in clinical development.

Multicenter Clinical and Molecular Epidemiological Analysis of Bacteremia Due to Carbapenem-Resistant Enterobacteriaceae (CRE) in the CRE Epicenter of the United States

Although the New York/New Jersey (NY/NJ) area is an epicenter for carbapenem-resistant Enterobacteriaceae (CRE), there are few multicenter studies of CRE from this region. We characterized patients with CRE bacteremia in 2013 at eight NY/NJ medical centers and determined the prevalence of carbapenem resistance among Enterobacteriaceae bloodstream isolates and CRE resistance mechanisms, genetic backgrounds, capsular types (cps), and antimicrobial susceptibilities. Of 121 patients with CRE bacteremia, 50% had cancer or had undergone transplantation. The prevalences of carbapenem resistance among Klebsiella pneumoniae, Enterobacter spp., and Escherichia coli bacteremias were 9.7%, 2.2%, and 0.1%, respectively. Ninety percent of CRE were K. pneumoniae and 92% produced K. pneumoniae carbapenemase (KPC-3, 48%; KPC-2, 44%). Two CRE produced NDM-1 and OXA-48 carbapenemases. Sequence type 258 (ST258) predominated among KPC-producing K. pneumoniae (KPC-Kp). The wzi154 allele, corresponding to cps-2, was present in 93% of KPC-3-Kp, whereas KPC-2-Kp had greater cps diversity. Ninety-nine percent of CRE were ceftazidime-avibactam (CAZ-AVI)-susceptible, although 42% of KPC-3-Kp had an CAZ-AVI MIC of ≥4/4 μg/ml. There was a median of 47 h from bacteremia onset until active antimicrobial therapy, 38% of patients had septic shock, and 49% died within 30 days. KPC-3-Kp bacteremia (adjusted odds ratio [aOR], 2.58; P = 0.045), cancer (aOR, 3.61, P = 0.01), and bacteremia onset in the intensive care unit (aOR, 3.79; P = 0.03) were independently associated with mortality. Active empirical therapy and combination therapy were not associated with survival. Despite a decade of experience with CRE, patients with CRE bacteremia have protracted delays in appropriate therapies and high mortality rates, highlighting the need for rapid diagnostics and evaluation of new therapeutics.

Efflux in the Oral Metagenome: The Discovery of a Novel Tetracycline and Tigecycline ABC Transporter

Antibiotic resistance in human bacterial pathogens and commensals is threatening our ability to treat infections and conduct common medical procedures. As novel antibiotics are discovered and marketed it is important that we understand how resistance to them may arise and know what environments may act as reservoirs for such resistance genes. In this study a tetracycline and tigecycline resistant clone was identified by screening a human saliva metagenomic library in Escherichia coli EPI300 on agar containing 5 μg/ml tetracycline. Sequencing of the DNA insert present within the tetracycline resistant clone revealed it to contain a 7,765 bp fragment harboring novel ABC half transporter genes, tetAB(60). Mutagenesis studies performed on these genes confirmed that they were responsible for the tetracycline and tigecycline resistance phenotypes. Growth studies performed using E. coli EPI300 clones that harbored either the wild type, the mutated, or none of these genes indicated that there was a fitness cost associated with presence of these genes, with the isolate harboring both genes exhibiting a significantly slower growth than control strains. Given the emergence of E. coli strains that are sensitive only to tigecycline and doxycycline it is concerning that such a resistance mechanism has been identified in the human oral cavity.

New antibiotic strategies in patients with cirrhosis and bacterial infection

Early diagnosis and adequate empirical antibiotic treatment of bacterial infections in advanced cirrhosis is essential to improve outcomes given the high risk of developing severe sepsis, multiple organ failure and death. β-lactams and quinolones are nowadays frequently ineffective in nosocomial and healthcare associated infections, due to the increasing prevalence of multidrug resistant (MDR) bacteria reported across different geographical areas. Recent antibiotic exposure also increases the risk of developing MDR bacterial infections. Initial antibiotic strategies should therefore be tailored according to the presence or absence of risk factors of MDR bacteria and to the severity of infection and should consider the local epidemiology. Empirical treatment in the population at high risk of MDR bacterial infections requires the use of broad-spectrum antibiotics (carbapenems or tigecycline) and of drugs active against specific resistant bacteria (glycopeptides, linezolid, daptomycin, amikacin, colistin). Early de-escalation policies are recommended to prevent the spread of MDR bacteria in cirrhosis.

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.

In Vitro Activity of Eravacycline against Carbapenem-Resistant Enterobacteriaceae and Acinetobacter baumannii

Eravacycline and comparators were tested against carbapenem- and tigecycline-resistant Enterobacteriaceae and Acinetobacter isolates received at the United Kingdom's national reference laboratory. Eravacycline MICs correlated closely with those of tigecycline but mostly were around 2-fold lower; both molecules retained full activity against isolates with high-level tetracycline and minocycline resistance. MIC90s of eravacycline and tigecycline were raised ca. 2-fold for carbapenem-resistant Enterobacteriaceae compared with carbapenem-susceptible controls, probably reflecting subsets of isolates with increased efflux.

Tigecycline Treatment for Carbapenem-Resistant Enterobacteriaceae Infections: A Systematic Review and Meta-Analysis

Carbapenem-resistant Enterobacteriaceae (CRE) infections are prevalent worldwide; they have few effective treatments and this jeopardizes public health. Clinicians often use tigecycline to combat CRE, but its clinical efficacy remains controversial. Therefore, to compare the efficacy and safety of tigecycline in treating CRE infections compared with that of other antimicrobial agents, and to evaluate whether combination therapy and high-dose regimens are beneficial, we performed a systematic review and meta-analysis. PubMed and Embase were searched for controlled trials or cohort studies reporting the efficacy and/or safety of tigecycline-based regimens to treat CRE infections. Statistical analyses were performed using the Comprehensive Meta-Analysis V2.2. All meta-analyses were performed based on fixed- or random-effects model, and the I method was used to assess heterogeneity. Twenty-one controlled studies and 5 single-arm studies were included in this systematic review. With regard to the controlled studies, the tigecycline groups did not differ significantly from the control groups in terms of overall mortality (Odds ratio (OR) = 0.96 [95% confidence interval (CI) = 0.75-1.22; P = 0.73]), clinical response rate (OR = 0.58 [95% CI = 0.31-1.09; P = 0.09]), or microbiological response rate (OR = 0.46 [95% CI = 0.15-1.44; P = 0.18]). Subgroup analyses showed that 30-day mortality was significantly lower in patients who received tigecycline combination therapy than in those who received monotherapy (OR = 1.83 [95% CI = 1.07-3.12; P = 0.03]) and other antibiotic regimens (OR = 0.59 [95% CI = 0.39-0.88; P = 0.01]), respectively. In addition, high-dose tigecycline regimens differed significantly from standard dose schedules in terms of ICU mortality (OR = 12.48 [95% CI = 2.06-75.43; P = 0.006]). The results of the 5 single-arm studies corroborated the findings of the controlled studies. Our results indicated that the efficacy of tigecycline in treating CRE infections is similar to that of other antibiotics. Tigecycline combination therapy and high-dose regimens may be more effective than monotherapy and standard-dose regimens, respectively. Nonetheless, considering that the current available evidence is limited, well-designed randomized controlled trials are urgently needed to clarify the comparative efficacy of tigecycline in treating CRE infections.