Once Daily High Dose Tigecycline Is Optimal: Tigecycline PK/PD Parameters Predict Clinical Effectiveness

Low levels of tetracyclines select for a mutation that prevents the evolution of high-level resistance to tigecycline

In a collection of Escherichia coli isolates, we discovered a new mechanism leading to frequent and high-level tigecycline resistance involving tandem gene amplifications of an efflux pump encoded by the tet(A) determinant. Some isolates, despite carrying a functional tet(A), could not evolve high-level tigecycline resistance by amplification due to the presence of a deletion in the TetR(A) repressor. This mutation impaired induction of tetA(A) (encoding the TetA(A) efflux pump) in presence of tetracyclines, with the strongest effect observed for tigecycline, subsequently preventing the development of tet(A) amplification-dependent high-level tigecycline resistance. We found that this mutated tet(A) determinant was common among tet(A)-carrying E. coli isolates and analysed possible explanations for this high frequency. First, while the mutated tet(A) was found in several ST-groups, we found evidence of clonal spread among ST131 isolates, which increases its frequency within E. coli databases. Second, evolution and competition experiments revealed that the mutation in tetR(A) could be positively selected over the wild-type allele at sub-inhibitory concentrations of tetracyclines. Our work demonstrates how low concentrations of tetracyclines, such as those found in contaminated environments, can enrich and select for a mutation that generates an evolutionary dead-end that precludes the evolution towards high-level, clinically relevant tigecycline resistance.

A study on evolution of antimicrobial resistance reveals how sub-inhibitory concentrations of antibiotics enrich and select for a mutated allele that prevents evolution towards clinically significant levels of antibiotic resistance.

Tigecycline-Associated Coagulopathy: A Single-Center Retrospective Analysis

INTRODUCTION

The purpose of this study was to assess clinical characteristics and risk factors for tigecycline-associated prothrombin time (PT) and activated partial thromboplastin time (aPTT) prolongation.

METHODS

We performed a retrospective analysis on coagulation parameters before and during tigecycline treatment in 55 patients in our hospital with severe infections, mainly pneumonia caused by Acinetobacter baumannii. Patients were divided into different groups according to prolongation of PT and aPTT, and clinical features involved were explored. Univariate and multivariable binary logistic regression analyses were used to identify risk factors for tigecycline-associated PT and aPTT increase.

RESULTS

We found that PT values increased from 12.73 ± 1.87 to 13.86 ± 2.06 during the treatment compared with premedication (p < 0.001), and the aPTT level prolonged significantly from 33.63 ± 11.24 to 38.15 ± 11.81 (p < 0.001). The multivariate analyses identified 2 variables that were associated with tigecycline-induced PT prolongation: albumin level (p = 0.018) and weight-adjusted tigecycline dosage (p = 0.005). In addition, treatment duration was the only risk factor for tigecycline-induced aPTT prolongation (p = 0.043).

CONCLUSION

Albumin level, weight-adjusted tigecycline dosage, treatment duration may serve as risk indicators for tigecycline-associated coagulation dysfunction. Physicians should be careful with coagulation disorder when prescribing tigecycline in clinical practice, especially in patients with risk factors.

Machine perfusion combined with antibiotics prevents donor-derived infections caused by multidrug-resistant bacteria

Donor infection affects organ utilization, especially the infections by multidrug-resistant bacteria, which may have disastrous outcomes. We established a rat model, inoculated with Escherichia coli or carbapenem-resistant Klebsiella pneumoniae (CRKP), to investigate whether hypothermic machine perfusion (HMP), normothermic machine perfusion (NMP), or static cold storage (SCS) combined with antibiotic (AB) could eliminate the bacteria. E. coli or CRKP-infected kidneys were treated with cefoperazone-sulbactam and tigecycline, respectively. The HMP+AB and NMP+AB treatments had significant therapeutic effects on E. coli or CRKP infection compared with the SCS+AB treatment. The bacterial load of CRKP-infected kidneys in the HMP+AB (22 050 ± 2884 CFU/g vs. 1900 ± 400 CFU/g, p = .007) and NMP+AB groups (25 433 ± 2059 CFU/g vs. 500 ± 458 CFU/g, p = .002) were significantly reduced, with no statistically significant difference between both groups. Subsequently, the CRKP-infected kidneys of the HMP+AB and SCS+AB groups were transplanted. The rats in the SCS+AB group were severe infected and euthanized on day 4 post-transplant. By contrast, the rats in the HMP+AB group were in good condition. In conclusion, HMP and NMP combined with AB seems to be efficient approaches to decrease bacterial load of infected kidneys. This might lead to higher utilization rates of donors with active infection.

Progression of Fibrinogen Decrease during High Dose Tigecycline Therapy in Critically Ill Patients: A Retrospective Analysis

Tigecycline is a novel glycylcycline broad-spectrum antibiotic offering good coverage for critically ill patients experiencing complicated infections. A known side effect is a coagulation disorder with distinct hypofibrinogenemia. To date, the information on possible risk factors and outcomes is sparse. Therefore, the aim of this study is to examine the time course of fibrinogen level changes during tigecycline therapy in critically ill patients. Moreover, we sought to identify risk factors for coagulopathy and to report on clinically important outcomes. We retrospectively reviewed all intensive care patients admitted to our General and Surgical Intensive Care Unit receiving tigecycline between 2010 and 2018. A total of 130 patients were stratified into two groups based on the extent of fibrinogen decrease. Patients with a greater fibrinogen decrease received a higher dose, a longer treatment and more dose changes of tigecycline, respectively. In regard to the underlying pathology, these patients showed higher inflammation markers as well as a slightly reduced liver synthesis capacity. We, therefore, conclude that such a fibrinogen decrease may be based upon further impairment of liver synthesis during severe inflammatory states. To decrease the risk of bleeding, cautious monitoring of coagulation in critically ill patients treated with high-dose tigecycline is warranted.

High-Dose versus Standard-Dose Tigecycline Treatment of Secondary Bloodstream Infections Caused by Extensively Drug-Resistant Acinetobacter baumannii: An Observational Cohort Study

Background

Extensively drug-resistant Acinetobacter baumannii (XDR-AB) infections have become difficult to treat and are associated with a high mortality rate. Tigecycline is one of the most effective agents used to treat XDR-AB infections, but data from treating bloodstream infection (BSI) in standard dose do not look promising, because of its low plasma concentration. Secondary BSI with primary infection source may indicate tigecycline treatment with a higher dose. Currently, little is known about the application of high-dose tigecycline among patients with secondary BSI caused by XDR-AB. We aimed to investigate the outcomes for high-dose (HD) tigecycline treatment versus standard-dose (SD) treatment of these patients.

Methods

An observational cohort study was conducted at four university affiliated hospitals in mainland China. Adult inpatients who were confirmed as having secondary BSI caused by XDR-AB and received definitive tigecycline treatment were consecutively included. Patients who were treated with 50 mg every 12 h were defined as the SD group, and a twice dose was defined as the HD group.

Results

Of the enrolled patients, 63 received SD and 88 received HD tigecycline treatment. Patients in the two groups had similar with regard to baseline clinical conditions. The 30-day survival was affected by the source of the primary infection. Survival was significantly better in patients with non-pulmonary-infection-related BSI than in patients with pulmonary-infection-related BSI. Multivariate Cox regression confirmed that HD had a protective effect only observed in patients with non-pneumonia-related BSI.

Conclusion

A tigecycline dose that is twice its standard dose is better for the treatment of XDR-AB infection only in BSI associated with non-pulmonary infection.

Treatment of Donor-derived Carbapenem-resistant Klebsiella pneumoniae Infection after Renal Transplantation with Tigecycline and Extended-infusion Meropenem

OBJECTIVE

Donor-derived carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has recently emerged as a critical early complication after renal transplantation. Although CRKP is usually sensitive to tigecycline, monotherapy with this drug is often less than effective. We investigated the efficacy of a combined regimen of tigecycline with high-dose, extended-infusion meropenem in the treatment of donor-derived CRKP infection after kidney transplantation.

METHODS

From Jan. 2016 to Dec. 2017, a total of 12 CRKP isolates were detected from cultures of the organ preservation solution used for soaking the donor kidneys at our institute. Probable or possible donor-derived infection (DDI) was identified in 8 transplant recipients. Clinical data were retrospectively analyzed.

RESULTS

Klebsiella pneumoniae carbapenemase-2 (KPC-2)-producing CRKP was reported to be positive in organ preservation solution cultures at 3.5±0.9 days after transplantation, leading to surgical site (n=3), urinary tract (n=4), and/or bloodstream (n=2) infections in 8 recipients. The drug susceptibility tests showed that CRKP was sensitive to tigecycline, but resistant to meropenem. In 7 patients who received tigecycline combined with high-dose extended-infusion meropenem, DDIs were successfully cured. The length of hospital stay was 31 (18-129) days, and the serum creatinine at discharge was 105.8±16.7 µmol/L. The one remaining patient who received tigecycline combined with intravenous-drip meropenem died of septic shock. A median follow-up of 43 months (33-55) showed no recurrence of new CRKP infection in the 7 surviving recipients.

CONCLUSION

It was suggested that a prompt and appropriate combination therapy using tigecycline with high-dose extended-infusion meropenem is effective in treating donor-derived KPC-2-producing CRKP infection after renal transplantation.

Is it time to move away from polymyxins?: evidence and alternatives

Increasing burden of carbapenem resistance and resultant difficult-to-treat infections are of particular concern due to the lack of effective and safe treatment options. More recently, several new agents with activity against certain multidrug-resistant (MDR) and extensive drug-resistant (XDR) Gram-negative pathogens have been approved for clinical use. These include ceftazidime-avibactam, meropenem-vaborbactam, imipenem-cilastatin-relebactam, plazomicin, and cefiderocol. For the management of MBL infections, clinically used triple combination comprising ceftazidime-avibactam and aztreonam is hindered due to non-availability of antimicrobial susceptibility testing methods and lack of information on potential drug-drug interaction leading to PK changes impacting its safety and efficacy. Moreover, in several countries including Indian subcontinent and developing countries, these new agents are yet to be made available. Under these circumstances, polymyxins are the only last resort for the treatment of carbapenem-resistant infections. With the recent evidence of suboptimal PK/PD particularly in lung environment, limited efficacy and increased nephrotoxicity associated with polymyxin use, the Clinical and Laboratory Standards Institute (CLSI) has revised both colistin and polymyxin B breakpoints. Thus, polymyxins 'intermediate' breakpoint for Enterobacterales, P. aeruginosa, and Acinetobacter spp. are now set at ≤ 2 mg/L, implying limited clinical efficacy even for isolates with the MIC value 2 mg/L. This change has questioned the dependency on polymyxins in treating XDR infections. In this context, recently approved cefiderocol and phase 3 stage combination drug cefepime-zidebactam assume greater significance due to their potential to act as polymyxin-supplanting therapies.

Pharmacokinetics of tigecycline in critically ill patients with liver failure defined by maximal liver function capacity test (LiMAx)

BACKGROUND

In critically ill patients, tigecycline (TGC) remains an important therapeutic option due to its efficacy against multiresistant Gram-positive and Gram-negative bacteria. TGC is metabolized and eliminated predominantly by the liver. Critical illness-induced liver failure may have a profound impact on the pharmacokinetic of TGC. In the present study, we aimed to establish a link between the degree of liver dysfunction and TGC plasma concentration using the novel maximum liver function capacity (LiMAx) test, as a dynamic liver function test.

MATERIALS/METHODS

The prospective study included 33 patients from a surgical ICU with the clinical indication for antibiotic therapy with TGC. The patients received 100 mg loading dose of TGC followed by intermittent standard doses of 50 mg q12. Blood samples for TGC plasma concentration were collected at 0.3, 2, 5, 8 and 11.5 h in a steady-state condition after at least 36 h post-standard dosage. The results were analyzed by means of a high-performance liquid chromatography (HPLC) method. Within the same day, the LiMAx test was carried out and routine blood parameters were measured.

RESULTS

Peak plasma concentrations of TGC were significantly higher in patients with severe liver failure (LiMAx < 100 µg/kg/h) when compared to patients with normal liver function (LiMAx > 300 µg/kg/h). The pharmacokinetic curves revealed higher values in severe liver failure at any measured point. Moreover, LiMAx and total bilirubin were the only liver-related parameters that correlated with TGC C_max.

CONCLUSIONS

The present study demonstrates a high variability of TGC plasma concentrations in critically ill patients. The results show a significant correlation between the degree of liver dysfunction, measured by the LiMAx test, and TGC C_max. LiMAx test may be a helpful tool beyond others for adjusting the required dosage of hepatic metabolized antibiotics in critically ill patients. Trial registry DRKS-German clinical trials register; Trial registration number: DRKS00008888; Date of registration: 07-17-2015; Date of enrolment of the first participant to the trial: 12-10-2015.

Clinical characteristics and risk factors of tigecycline-associated hypofibrinogenaemia in critically ill patients

Purpose

To analyze the clinical features and risk factors of tigecycline-associated hypofibrinogenaemia and study whether cefoperazone/sulbactam combined with tigecycline aggravates coagulopathy or hypofibrinogenaemia.

Methods

A retrospective case–control study of patients with severe infection who were treated with tigecycline was conducted. Patients were assigned to the hypofibrinogenaemia group (< 2.0 g/L) and normal fibrinogen (normal) group (≥ 2.0 g/L) to assess the clinical features of patients with tigecycline-associated hypofibrinogenaemia. The traits of patients treated with cefoperazone/sulbactam in the hypofibrinogenaemia group were also analyzed.

Results

In total, 127 patients were enrolled in the study, including 71 patients with hypofibrinogenaemia and 56 patients with normal fibrinogen levels. Hypofibrinogenaemia developed at a median of 6 (4–8) days after tigecycline treatment, and the fibrinogen level returned to normal at a median of 3 (3–5) days after tigecycline discontinuation. In the multivariate analysis, intra-abdominal infection (p = 0.005), fibrinogen level at tigecycline initiation (p < 0.001), maintenance dose (p = 0.039), and treatment duration (p = 0.002) were found to be related to hypofibrinogenaemia. Treatment with cefoperazone/sulbactam was not associated with hypofibrinogenaemia (p = 0.681), but patients treated with cefoperazone/sulbactam had a higher incidence of coagulopathy (p = 0.009) and needed more blood products (p = 0.003) than those treated without cefoperazone/sulbactam.

Conclusion

Tigecycline-associated hypofibrinogenaemia often developed on the 6th (4th–8th) day of tigecycline use and was associated with intra-abdominal infection, fibrinogen level at tigecycline initiation, maintenance dose, and treatment duration of tigecycline but not cefoperazone/sulbactam.

Clostridioides difficile-Associated Antibiotics Alter Human Mucosal Barrier Functions by Microbiome-Independent Mechanisms

A clinically relevant risk factor for Clostridioides difficile-associated disease (CDAD) is recent antibiotic treatment. Although broad-spectrum antibiotics have been shown to disrupt the structure of the gut microbiota, some antibiotics appear to increase CDAD risk without being highly active against intestinal anaerobes, suggesting direct nonantimicrobial effects. We examined cell biological effects of antibiotic exposure that may be involved in bacterial pathogenesis using an in vitro germfree human colon epithelial culture model. We found a marked loss of mucosal barrier and immune function with exposure to the CDAD-associated antibiotics clindamycin and ciprofloxacin, distinct from the results of pretreatment with an antibiotic unassociated with CDAD, tigecycline, which did not reduce innate immune or mucosal barrier functions. Importantly, pretreatment with CDAD-associated antibiotics sensitized mucosal barriers to C. difficile toxin activity in primary cell-derived enteroid monolayers. These data implicate commensal-independent gut mucosal barrier changes in the increased risk of CDAD with specific antibiotics and warrant further studies in in vivo systems. We anticipate this work to suggest potential avenues of research for host-directed treatment and preventive therapies for CDAD.

Successful High-Dosage Monotherapy of Tigecycline in a Multidrug-Resistant Klebsiella pneumoniae Pneumonia-Septicemia Model in Rats

Background: Recent scientific reports on the use of high dose tigecycline monotherapy as a “drug of last resort” warrant further research into the use of this regimen for the treatment of severe multidrug-resistant, Gram-negative bacterial infections. In the current study, the therapeutic efficacy of tigecycline monotherapy was investigated and compared to meropenem monotherapy in a newly developed rat model of fatal lobar pneumonia–septicemia. Methods: A Klebsiella pneumoniae producing extended-spectrum β-lactamase (ESBL) and an isogenic variant producing K. pneumoniae carbapenemase (KPC) were used in the study. Both strains were tested for their in vitro antibiotic susceptibility and used to induce pneumonia–septicemia in rats, which was characterized using disease progression parameters. Therapy with tigecycline or meropenem was initiated at the moment that rats suffered from progressive infection and was administered 12-hourly over 10 days. The pharmacokinetics of meropenem were determined in infected rats. Results: In rats with ESBL pneumonia–septicemia, the minimum dosage of meropenem achieving survival of all rats was 25 mg/kg/day. However, in rats with KPC pneumonia–septicemia, this meropenem dosage was unsuccessful. In contrast, all rats with KPC pneumonia–septicemia were successfully cured by administration of high-dose tigecycline monotherapy of 25 mg/kg/day (i.e., the minimum tigecycline dosage achieving 100% survival of rats with ESBL pneumonia–septicemia in a previous study). Conclusions: The current study supports recent literature recommending high-dose tigecycline as a last resort regimen for the treatment of severe multidrug-resistant bacterial infections. The use of ESBL- and KPC-producing K. pneumoniae strains in the current rat model of pneumonia–septicemia enables further investigation, helping provide supporting data for follow-up clinical trials in patients suffering from severe multidrug-resistant bacterial respiratory infections.

Once-daily tigecycline for outpatient parenteral antibiotic therapy: a single-centre observational study

Background

Tigecycline has potential utility in the treatment of complex polymicrobial infections or those caused by MDR organisms in the ambulatory care setting owing to its breadth of antimicrobial coverage. Whilst licensed for twice-daily IV administration, its long half-life permits once-daily administration, which may facilitate successful outpatient parenteral antibiotic therapy (OPAT).

Methods

A retrospective case series of patients receiving once-daily tigecycline under OPAT was analysed at a single-centre NHS acute hospital (January 2016-June 2018). Patient demographics, including comorbidities, antimicrobial indication, concurrent antimicrobial therapies, treatment duration and adverse events related to treatment were recorded using medical records. Treatment outcomes were defined using the BSAC National Outcomes Registry System (NORS).

Results

A total of 25 treatment episodes (24 individual patients) were analysed. The most common indications were bone and joint infections (n = 8) and intra-abdominal infections (n = 7). MDR organisms were common, including ESBL-producing Enterobacterales (n = 13) and glycopeptide-resistant enterococci (n = 4). Median treatment duration was 18 days. Nineteen of 25 (76%) cases had complete cure of treatment, 3 patients experienced treatment-related adverse reactions necessitating cessation of therapy and 3 experienced failure due to disease progression. Eight patients experienced non-limiting adverse effects, such as nausea, vomiting and rash, and one patient had a transient rise in amylase 3 times the upper normal limit (with no evidence of pancreatitis).

Conclusions

Once-daily tigecycline can be successfully used for management of complex infections in the OPAT setting, with predominantly mild adverse effects, which can be managed with antiemetics or slow administration.

Efficacy and safety of high-dose tigecycline for the treatment of infectious diseases: A meta-analysis

BACKGROUND

High-dose (HD) tigecycline regimen is increasingly used in infectious diseases, however its efficacy and safety versus low-dose (LD) is still unclear.

METHODS

A systematic review and meta-analysis was performed; PubMed, Embase, Cochrane Library, ScienceDirect, Web of Science, clinicalTrials.gov, Wanfang, VIP, and China National Knowledge Infrastructure (CNKI), were searched using terms "tigecycline" AND "dose" up to October 31, 2018. Eligible studies were randomized trials or cohort studies comparing mortality, clinical response, microbiological eradication and safety of different tigecycline dose regimens for any bacterial infection. The primary outcome was mortality, and the secondary outcomes were clinical response rate, microbiological eradiation rate and adverse events (AEs). Meta-analysis was done with random-effects model, with risk ratios (RR) and 95% confidence intervals (CI) calculated for all outcomes.

RESULTS

Of 951 publications retrieved, 17 studies (n = 1041) were pooled in our meta-analysis. The primary outcome was available in 11 studies, and the RR for mortality was 0.67 (95% CI 0.53-0.84, P < .001). Clinical response (RR 1.46, 95% CI 1.30-1.65, P < .001) and microbiological eradication rate (RR 1.61, 95% CI 1.35-1.93, P < .001) were both higher in HD than in LD tigecycline regimen. However, non-Chinese study subgroup presented no statistical significance between HD and LD regimen, RR for mortality, clinical response and microbiological eradication were 0.79 (95% CI 0.56-1.14, P = .21), 1.35 (95% CI 0.96-1.92, P = .26), 1.00 (95% CI 0.22-4.43, P = 1.00), respectively. AEs did not differ between HD and LD tigecycline (RR 1.00, 95% CI 0.80-1.26, P = .97).

CONCLUSION

HD tigecycline regimen reduced mortality meanwhile improved clinical efficacy and should be considered in serious infections caused by multidrug-resistant and extensively drug-resistant (MDR/XDR) bacteria.