Multistate Outbreak of Listeriosis Linked to Turkey Deli Meat and Subsequent Changes in US Regulatory Policy

Exploring the impact of baseline platelet count on linezolid-induced thrombocytopenia: a retrospective single-center observation study

BACKGROUND

Patients treated with linezolid (LZD) frequently develop thrombocytopenia, and previous studies have identified the risk factors for this condition. However, the relationship between the development of LZD-induced thrombocytopenia and baseline platelet count has varied according to different reports.

AIM

To explore the relationship between platelet count and the development of LZD-induced thrombocytopenia.

METHOD

Patients who underwent LZD at Hokkaido University Hospital in Japan from September 2008 to March 2023 were included. We collected data on patient characteristics and platelet counts at baseline and during LZD therapy from the electronic medical records. Thrombocytopenia was defined as a decrease in platelet count by 30% or more from baseline, or a platelet level < 100,000/µL.

RESULTS

Two hundred and ninety-five patients who received LZD were included in this study, of whom 34.9% developed thrombocytopenia. In the early days of LZD treatment, the thrombocytopenia group showed a nearly 5% decrease in platelet count, while the non-thrombocytopenia group exhibited an increase of over 5%. Additionally, focusing on early onset thrombocytopenia (within 5 days), a baseline platelet count of < 150,000/µL was identified as a risk factor for early thrombocytopenia. Conversely, it was also observed that 24.7% of patients with a baseline platelet count ≥ 150,000/µL still developed early thrombocytopenia.

CONCLUSION

Our findings suggest that while a baseline platelet count of < 150,000/µL is a risk factor for the early onset of thrombocytopenia, vigilant monitoring of platelet counts by clinical pharmacists in the early stages of LZD treatment is essential, regardless of baseline platelet levels.

Development and validation of a risk prediction model for linezolid-induced anemia in elderly patients: a retrospective cohort study

Background

Linezolid-induced anemia (LI-AN) is a severe adverse reaction, but risk factors of the LI-AN for elderly patients have not been established.

Objectives

The objective of this study was to develop a nomogram capable of predicting LI-AN in elderly patients.

Design

This is a retrospective study to develop and validate a nomogram for anemia prediction in elderly patients treated with linezolid.

Methods

We retrospectively screened elderly patients treated with linezolid at Inner Mongolia People's Hospital from January 2020 to December 2023 and validated our findings using the MIMIC-IV 2.2 database. Anemia was defined as hemoglobin reduction to 75% of baseline value. Univariate and multivariable logistic regression models were used to identify predictors and construct the nomogram, which was evaluated using receiver operating characteristic (ROC) curve analysis, calibration plot, and decision curve analysis.

Results

A total of 231 patients were enrolled in this study. The training set comprised 151 individuals, and anemia occurred in 28 cases (18.54%). In the external validation set of 80 individuals, 26 (32.5%) were diagnosed with anemia. The predictors included duration of linezolid therapy, patient estimated glomerular filtration rate value, and sequential organ failure assessment score ⩾2. The ROC curve for the training set was 0.830 (95% CI: 0.750-0.910), while a similar ROC curve of 0.743 (95% CI: 0.621-0.865) was obtained for the validation set. The calibration curve demonstrated good correlation between predicted and observed results, indicating that this study effectively predicts risk factors associated with LI-AN in elderly patients.

Conclusion

The developed prediction model can provide valuable guidance for clinicians to prevent anemia and facilitate rational linezolid use in elderly patients.

Comparison of incidence of hyponatremia between linezolid and vancomycin in neonates and infants

A previous study reported that the incidence of hyponatremia after linezolid (LZD) use was higher than that with vancomycin (VCM) use in adults. However, hyponatremia due to LZD in neonates and infants was not investigated. This study aimed to compare the incidence of hyponatremia between LZD and VCM use in neonates and infants. The retrospective study was conducted at the Aichi Medical University Hospital. All patients who were cared for in NICU or GCU and received ≥3 days of LZD or VCM were included in this study. Hyponatremia was defined as serum sodium level ≤134 mEq/L and ≥5 % decrease from baseline after administration of LZD or VCM. A total of 76 patients (LZD, N = 36; VCM, N = 37) were included. There was no significant difference in the incidence of hyponatremia between the two groups (19.4 % vs 16.2 %, p = 0.72). The proportion of patients with a minimum value of serum sodium ≤134 mEq/L during treatment was 47.3 % in the LZD group and 35.1 % in the VCM group (p = 0.29), and the decrease in serum sodium level from baseline to the minimum value was 80.5 % and 78.4 %, respectively (p = 0.85). In conclusion, there was no significant difference in the incidence of hyponatremia between the LZD and VCM groups. Therefore, it is not necessary to avoid LZD use in neonates and infants because of the risk of hyponatremia.

Contribution of human organic anion transporter 3-mediated transport of a major linezolid metabolite, PNU-142586, in linezolid-induced thrombocytopenia

Thrombocytopenia, a common adverse effect of linezolid, often occurs in patients lacking typical risk factors. In this study, we investigated the key risk factors for linezolid-induced thrombocytopenia using two real-world clinical databases and explored its underlying mechanism through in vitro and in vivo experiments. In a retrospective analysis of 150 linezolid-treated patients, multivariate analysis identified coadministration of lansoprazole, a proton pump inhibitor, as a significant independent risk factor for thrombocytopenia (odds ratio: 2.33, p = 0.034). Additionally, analysis of the Food and Drug Administration Adverse Event Reporting System database revealed a reporting odds ratio of thrombocytopenia for lansoprazole of 1.64 (95% CI: 1.25-2.16). In vitro studies showed that the uptake of PNU-142586, a major linezolid metabolite, was significantly higher in human organic anion transporter 3-expressing HEK293 (HEK-hOAT3) cells compared to HEK-pBK cells. The apparent IC50 value of lansoprazole against hOAT3-mediated transport of PNU-142586 was 0.59 ± 0.38 µM. In a pharmacokinetic study using rats, coadministration of linezolid with lansoprazole intravenously resulted in approximately a 1.7-fold increase in the area under the plasma concentration-time curve of PNU-142586, but not linezolid and PNU-142300. Moreover, PNU-142586, but not linezolid, exhibited concentration-dependent cytotoxicity in a human megakaryocytic cell line. These findings suggest that linezolid-induced thrombocytopenia should be due to delayed elimination of PNU-142586. Furthermore, delayed elimination of PNU-142586 due to renal failure and hOAT3-mediated transport inhibition by lansoprazole should exacerbate linezolid-induced thrombocytopenia.

Preclinical toxicity evaluation of novel antibacterial contezolid acefosamil in rats and dogs

Contezolid acefosamil (CZA) is an intravenous prodrug of oxazolidinone antibiotic contezolid (CZD). It is being developed to treat infections due to Gram-positive bacteria including multidrug-resistant pathogens, while addressing myelosuppression and neurotoxicity limitations associated with long-term use of this class of antibiotics. In vivo, CZA is rapidly deacylated into its first metabolite MRX-1352, which is then dephosphorylated to release active drug CZD. Four-week repeat-dose toxicity studies of intravenous CZA were conducted in Sprague-Dawley rats (40, 80, and 160/120 mg/kg/dose twice a day [BID]) and beagle dogs (25, 50, and 100/75 mg/kg/dose BID). The high doses administered to both rats and dogs were adjusted due to adverse effects including decreased body weight and food consumption. Additionally, a dose-dependent transient reduction in erythrocyte levels was recorded at the end of dosing phase. Importantly, no myelosuppressive reduction in platelet counts was observed, in contrast to the myelosuppression documented for standard-of-care oxazolidinone linezolid. The no-observed-adverse-effect level (NOAEL) of CZA was 80 and 25 mg/kg/dose BID in rats and dogs, respectively. Separately, 3-month neuropathological evaluation in Long-Evans rats (25, 37.5, and 50 mg/kg/dose, oral CZA, BID) demonstrated no neurotoxicity in the central, peripheral, and optical neurological systems. Toxicokinetic data from these studies revealed that CZD exposures at NOAELs were higher than or comparable with that for the intended clinical dose. These results confirm the favorable safety profile for CZA and support its clinical evaluation for long-term therapy of persistent Gram-positive infections, beyond the application for earlier oxazolidinones.

Linezolid-Induced Thrombocytopenia in Patients with Renal Impairment: A Case Series, Review and Dose Advice

BACKGROUND AND OBJECTIVE

Oral linezolid is often used as alternative therapy for intravenous vancomycin. According to the current guidelines, no dose adjustment has to be made in case of renal impairment. Nevertheless, in our hospital we have seen several patients with renal impairment who developed linezolid-induced thrombocytopenia when linezolid was taken in the standard dose. In this case series and review we want to emphasize the necessity of reviewing the Dutch and international guidelines.

METHODS

We describe five cases with renal impairment that developed linezolid-induced thrombocytopenia in our hospital. A PubMed literature review was conducted to identify other cases and find the optimal dosing regimen for these patients.

RESULTS

Our cases join a long list of cases and available literature about linezolid-induced thrombocytopenia in patients with renal impairment. Less linezolid-induced thrombocytopenia was found, both in our cases and in the literature, after dose reduction of 50%. High linezolid trough concentrations were associated with a higher risk of linezolid-induced thrombocytopenia. Besides renal impairment, other risk factors for developing linezolid-induced thrombocytopenia were also identified, such as low body weight, high daily dose/kg, higher age, longer duration of therapy, low baseline count, malignity, low-dose aspirin and interacting co-medication.

CONCLUSION

Re-evaluation of the current dose advice is necessary. We advocate for a standard dose reduction to 50% after 2 days of standard dosing for all patients with an estimated glomerular filtration of <60 mL/min/1.73 m2. Besides this, therapeutic drug monitoring and thrombocytes monitoring may be executed weekly when patients have renal impairment or other risk factors for developing linezolid-induced thrombocytopenia.

Linezolid-induced lactic acidosis

Linezolid is a commonly prescribed antibiotic in clinical practice. Although thrombocytopenia and peripheral neuropathy are frequently encountered following prolonged administration of linezolid, lactic acidosis is a rare adverse drug reaction. We present the case of a patient on linezolid for disseminated multidrug-resistant tuberculosis who presented with vomiting, dyspnoea, hypotension and high anion gap metabolic acidosis. The initial presentation mimicked sepsis syndrome. Ketoacidosis and renal dysfunction were ruled out. There was no history of ingestion of toxins/toxic alcohols. Sepsis was unlikely because extensive radiological and microbiological testing could not identify an infection. Given the possibility of linezolid-induced lactic acidosis (LILA), linezolid was discontinued on admission. The patient's lactic acidosis resolved, and his overall condition improved. A retrospective diagnosis of LILA was thus established. LILA should be considered when patients on linezolid present with lactic acidosis and other causes for the lactic acidosis have been ruled out.

Risk factors for post-polypectomy bleeding in patients with end-stage renal disease undergoing colonoscopic polypectomy

BACKGROUND AND AIMS

Little is known about the risk factors of bleeding after colonoscopic polypectomy in patients with end-stage renal disease (ESRD). This study investigated the incidence and risk factors of post-polypectomy bleeding (PPB), including immediate and delayed bleeding, in patients with ESRD.

METHODS

Ninety-two patients with ESRD who underwent colonoscopic polypectomy between September 2005 and June 2020 at a single tertiary referral center were included. The patients' medical records were retrospectively reviewed. Patient- and polyp-related factors associated with immediate PPB (IPPB) were analyzed using logistic regression analysis. Additionally, the optimal cutoff polyp size related to a significant increase in the risk of IPPB was determined by performing receiver operating characteristic (ROC) analysis and calculating the area under the ROC curve (AUC).

RESULTS

In total, 286 polyps were removed. IPPB occurred in 24 (26.1%) patients and 46 (16.1%) polyps and delayed PPB occurred in 2 (2.2%) patients. According to multivariate analysis, the polyp size (> 7 mm), old age (> 70), and endoscopic mucosal resection (EMR) as the polypectomy method (EMR versus non-EMR) were found to be independent risk factors for IPPB. According to the Youden index method, the optimal cutoff polyp size to identify high-risk polyps for IPPB was 7 mm (AUC = 0.755; sensitivity, 76.1%; specificity, 69.6%).

CONCLUSIONS

Colonoscopic polypectomy should be performed with caution in patients with ESRD, especially in those with the following risk factors: advanced age (> 70 years), polyp size > 7 mm, and EMR as the polypectomy method.

Disseminated nocardiosis with persistent neurological disease

A man in his 80s with a history of sarcoidosis on chronic prednisone presented to the emergency department with several days of dyspnoea. A chest X-ray showed signs of pneumonia, and the patient was admitted. Blood and pleural fluid cultures grew Nocardia farcinica; therefore, the patient was started on treatment with trimethoprim-sulbactam and imipenem. Brain imaging showed evidence of dissemination of the infection to the central nervous system (CNS). The patient's admission was complicated by pleural effusions, acute kidney injury and pancytopenia, and therefore, his antibiotic regimen was ultimately transitioned from trimethoprim-sulfamethoxazole (TMP-SMX), meropenem and linezolid to imipenem and tedizolid. The patient received imipenem and tedizolid for the remainder of the admission. A repeat MRI of the brain was performed after 6 weeks of this dual antibiotic therapy, which unfortunately revealed persistent CNS disease. His regimen was then broadened to TMP-SMX, linezolid and imipenem. Despite these measures, however, the patient ultimately passed away from the infection.

Risk factors for thrombocytopenia in patients receiving linezolid therapy: a systematic review and meta-analysis

PURPOSE

The incidence of linezolid-induced thrombocytopenia (LIT) has been reported to vary widely across studies. We performed a meta-analysis to identify the risk factors for thrombocytopenia among patients who received linezolid treatment.

METHODS

The PubMed, Embase and Cochrane Library databases were searched from inception to November 2022 to identify eligible studies. Data on the potential predictors of incidence in LIT were pooled using a random effects model. Sensitivity analyses were performed to determine the robustness of the results when significant heterogeneity was observed.

RESULTS

Forty observational studies involving 6454 patients treated with linezolid were included in the analysis. LIT was estimated to occur in 37% of patients. The following important factors were associated with the incidence of LIT: advanced age, body mass index, concurrent renal impairment or liver disease, abnormal laboratory parameters (including white blood cell count, serum creatinine, baseline platelet count, albumin, creatinine clearance rate, and estimated glomerular filtration rate), treatment duration and renal replacement therapy.

CONCLUSIONS

A variety of risk factors related to the occurrence of LIT were revealed in our analysis. Early identification of these factors could help patients improve clinical outcomes.

Effect of Platelet Parameters on Linezolid-Related Thrombocytopenia in Hospitalized Patients

Background

Linezolid-induced thrombocytopenia incidence varies considerably. Linezolid-related thrombocytopenia in patients has received few studies which have investigated risk factors including platelet parameters except for platelet counts. The study aims to analyze the effect of platelet parameters, including mean platelet volume and platelet large cell ratio, on linezolid-related thrombocytopenia in patients.

Methods

The effect of platelet parameters on linezolid-related thrombocytopenia was identified by univariate and multivariate logistic regressions. A Kaplan-Meier survival analysis was carried out to compare the survival of patients who developed linezolid-related thrombocytopenia with patients who did not.

Results

Thrombocytopenia occurred at a rate of 41.5% (66/159) after linezolid therapy in hospitalized patients. Platelet parameters, including the difference in mean platelet volume (MPV/fL=0.08 (-1.2-0.9)vs-0.5 (-1.5-0.3), (OR, 0.459; P = 0.001), the difference in platelet large cell ratio (PLCR/fL=0.9 (-5.1-6.2)vs-3.8 (-8.6-2.4), (OR, 1.156; P = 0.001), baseline platelet counts (OR, 0.995; P = 0.006) and duration of linezolid therapy≥10d (OR, 1.346; P = 0.007), were significantly associated with linezolid-related thrombocytopenia in hospitalized patients. In addition, other risk factors which also are associated with linezolid-related thrombocytopenia include baseline red blood cells, co-medication with parecoxib and co-medication with caspofungin. Accumulated in-hospital mortality of patients with thrombocytopenia was significantly higher than that of patients without thrombocytopenia during linezolid treatment (19.7% vs 8.6%, P = 0.003).

Conclusion

The difference in mean platelet volume, the difference in large platelet ratio, baseline platelet counts and duration of linezolid therapy≥10d significantly affected the development of linezolid-related thrombocytopenia in hospitalized patients.

Influence of augmented renal clearance on the lower incidence of linezolid-related hematological toxicity

OBJECTIVES

Linezolid is an oxazolidin commonly related to the development of hematological toxicity, being renal clearance the major factor involved in the drug clearance. The aim of this study is to evaluate the influence of increased filtration rates in the incidence of linezolid-induced hematological toxicity by comparing augmented renal clearance (ARC) patients versus normal renal function patients.

MATERIAL AND METHODS

A retrospective, observational study was conducted on hospitalized patients treated with linezolid for 5 days or more during 2014-2019 period. Patients with a filtration rate of ≥130 mL/min versus reference patients (60-90 mL/min) were compared. Hematological toxicity was defined as a decrease of 25% in platelets, of 25% in hemoglobin and/or 50% in neutrophils from baseline. Toxicity relevance was classified according to Common Terminology Criteria for Adverse Events v5. Incidence of hematological toxicity between groups was studied by chi-square and Fisher test. Furthermore, percentaje disminution of all three parameters was calculated and compared by Mann-Whitney test and treatment interruption and tranfusion requirements were registered.

RESULTS

30 ARC patients and 38 reference patients were included. Hematological toxicity was observed in 16.66% of ARC patients vs 44.74% of reference patients (p = 0.014); thrombocytopenia in 13.33% vs 36.84% (p = 0.051), anemia in 3.3% vs 10.52% (p = 0.374) and neutropenia in 10% vs 23.68% (p = 0.204). Median percentaje of platelets decrease in ARC patients was -10.36 (-193.33-62.03) vs 2.68 (-163.16-82.71) in reference patients (p = 0.333), while hemoglobin decrease was 2.50 (-12.12-25.93) vs 9.09 (-17.72-30.63) (p = 0.047) and neutrophils decrease was 9.14 (-73.91-76.47) vs 27.33 (-86.66-90.90) (p = 0.093). 10.5% of normal renal function patients reported at least one adverse event grade 3 or superior while 2.6% of them interrupted treatment and 5.2% had tranfusion requirements. No major events or interruptions were reported in ARC patients.

CONCLUSION

Our findings suggest a lower incidence and clinical relevance of hematological toxicity in augmented renal clearance patients. Thrombocytopenia was the major event in both populations. This might be related to a lower exposure to the drug due to the higher clearance and likely lower therapeutic efficiency. These results suggest a potential benefit of therapeutic drug monitoring on high risk patients.

[Translated article] Influence of augmented renal clearance in the lower incidence of linezolid-related haematological toxicity

OBJECTIVES

Linezolid is an oxazolidin commonly related to the development of haematological toxicity, being renal clearance the major factor involved in the drug clearance. The aim of this study is to evaluate the influence of increased filtration rates in the incidence of linezolid-induced haematological toxicity by comparing augmented renal clearance (ARC) patients versus normal renal function patients.

MATERIAL AND METHODS

A retrospective, observational study was conducted on hospitalized patients treated with linezolid for 5 days or more during 2014-2019 period. Patients with a filtration rate of ≥130 mL/min versus reference patients (60-90 mL/min) were compared. Haematological toxicity was defined as a decrease of 25% in platelets, of 25% in haemoglobin, and/or 50% in neutrophils from baseline. Toxicity relevance was classified according to Common Terminology Criteria for Adverse Events v5. Incidence of haematological toxicity between groups was studied by chi-square and Fisher test. Furthermore, percentage diminution of all 3 parameters was calculated and compared by Mann-Whitney test and treatment interruption and transfusion requirements were registered.

RESULTS

30 ARC patients and 38 reference patients were included. Haematological toxicity was observed in 16.66% of ARC patients vs 44.74% of reference patients (P=.014); thrombocytopenia in 13.33% vs 36.84% (P=.051), anaemia in 3.3% vs 10.52% (P=.374) and neutropenia in 10% vs 23.68% (P=.204). Median percentage of platelets decrease in ARC patients was -10.36 (-193.33-62.03) vs 2.68 (-163.16-82.71) in reference patients (P=.333), while haemoglobin decrease was 2.50 (-12.12-25.93) vs 9.09 (-17.72-30.63) (P=.047) and neutrophils decrease was 9.14 (-73.91-76.47) vs 27.33 (-86.66-90.90) (P=.093). 10.5% of normal renal function patients reported at least 1 adverse event grade 3 or superior while 2.6% of them interrupted treatment and 5.2% had transfusion requirements. No major events or interruptions were reported in ARC patients.

CONCLUSION

Our findings suggest a lower incidence and clinical relevance of haematological toxicity in augmented renal clearance patients. Thrombocytopenia was the major event in both populations. This might be related to a lower exposure to the drug due to the higher clearance and likely lower therapeutic efficiency. These results suggest a potential benefit of therapeutic drug monitoring on high risk patients.

Use of Japanese big data from electronic medical records to investigate risk factors and identify their high-risk combinations for linezolid-induced thrombocytopenia

PURPOSE

Thrombocytopenia is a major event associated with linezolid (LZD) therapy. Factors affecting LZD-induced thrombocytopenia (LIT) have been reported in previous studies. However, several issues pertaining to LIT have not yet been clarified. In the present study, we used Japanese big data to investigate associated factors and their high-risk combinations that influence LIT.

METHODS

Patients administered LZD between May 2006 and October 2020 were included in this study. LIT was defined as either a 30% or more reduction from the baseline platelets or platelet values of < 100,000/µL. We evaluated factors affecting LIT and combinations of factors that alter LIT risk according to a decision tree (DT) analysis, a typical machine learning method.

RESULTS

We successfully enrolled 1399 patients and LIT occurred in 44.7% of the patients (n = 626). We classified the laboratory data on renal function, LZD duration, age, and body weight (BW) into smaller categories. The results of multivariate analysis showed that prolonged LZD therapy, BW < 45 kg, estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m², and dialysis were risk factors for LIT. The DT analysis revealed that the highest risk was a combination of LZD duration ≥ 14 days and eGFR < 30 mL/min/1.73 m².

CONCLUSIONS

The present study extracted four risk factors and identified high-risk combinations for LIT. Patients with these risk factors should be closely monitored.

Linezolid-Induced Pancytopenia in Patients Using Dapagliflozin: A Case Series

Background

Linezolid is classed as oxazolidinone antibiotics which can be used to treat severe infections caused by vancomycin-resistant Enterococcus faecium, hospital-acquired pneumonia caused by Staphylococcus aureus, complicated skin, and uncomplicated skin structure infections (SSSIs) caused by methicillin-susceptible S. aureus or Streptococcus pyogenes, and community-acquired pneumonia caused by Streptococcus pneumoniae. However, many studies have suggested it can also cause thrombocytopenia and pancytopenia.

Patients and Methods

We report on three patients with linezolid-pancytopenia. Patients in cases 1 and 2 were diagnosed with heart failure with preserved ejection fraction (HFpEF) and were both administered with dapagliflozin, one of the sodium-dependent glucose transporters 2 inhibitors (SHLT-2i).

Results

Two patients were diagnosed with type 2 diabetes, pneumonia, and hyponatremia. Severe myelosuppression occurred in both patients, with a severe decrease in leukocytes and platelets and a moderate decrease in hemoglobin, who eventually passed away despite the discontinuation of linezolid and adopting appropriate treatment measures. The patient in case 3 was diagnosed with pneumonia, type 2 diabetes, and sequelae of cerebral thrombosis. After twelve days of treatment, the patient developed moderate thrombocytopenia and anemia. She recovered without any additional treatment after the discontinuation of linezolid.

Conclusion

In this case series, two patients with irreversible myelosuppression were treated with both linezolid and SGLT-2i, and one diabetic patient with single linezolid use presented with reversible pancytopenia, suggesting that SGLT-2i may exacerbate myelosuppression of linezolid. Linezolid should be used with caution in infectious patients with a history of SGLT-2i. We will conduct relevant animal experiments to clarify the interaction between the two drugs.

Linezolid-Induced Pure Red Cell Aplasia: A Case Report

Linezolid (LZD) has been widely used for treating the infections of multidrug-resistant gram-positive organisms. As we know, anemias induced by Linezolid (LZD) are common. However, LZD-induced pure red cell aplasia (PRCA) is very rare. In this paper, we report on a 68-year-old woman with intravascular stent infection who developed PRCA after treatment with LZD. The patient presented to our hospital with a 6-month history of fever after stent implantation for aneurysms in both lower limbs. Bone culture grew methicillin-resistant Staphylococcus hemolyticus (MRSH). She received LZD after developing adverse reactions to initial antibiotics. Although her infective symptoms were improved by LZD, progressive thrombocytopenia was observed 23 days after LZD therapy. Her platelets declined to 66*10⁹/L and hemoglobin level was 10.1 g/dL. Thrombocytopenia recovered 12 days after cessation of LZD. LZD was administered again due to recovered fever. 57 days after LZD administration, her hemoglobin level was 4.1 g/dL and reticulocytes were 0.2%. Bone marrow smear revealed active granulocyte proliferation and markedly decreased erythropoiesis with vacuolar degeneration. 12 days after cessation of LZD, her hemoglobin and reticulocyte levels rose to 9.6 g/dL and 5.1%, respectively. LZD was used for the third time as fever and inflammatory markers progressively increased, but Hb was reduced to 6.7g/dL 15 days after LZD therapy. 12 days after cessation of LZD, the hemoglobin level rose to 11.9 g/dL. In summary, we suggest complete blood count and reticulocyte count should be monitored to detect bone marrow suppression during long-term LZD therapy, especially in patients aged over 58 and/or with pre-existing anemia, chronic infections, and renal insufficiency.

A Review of Population Pharmacokinetic Analyses of Linezolid

In recent years, many studies on population pharmacokinetics of linezolid have been conducted. This comprehensive review aimed to summarize population pharmacokinetic models of linezolid, by focusing on dosage optimization to maximize the probability of attaining a certain pharmacokinetic-pharmacodynamic parameter in special populations. We searched the PubMed and EMBASE databases for population pharmacokinetic analyses of linezolid using a parametric non-linear mixed-effect approach, including both observational and prospective trials. Of the 32 studies, 26 were performed in adults, four in children, and one in both adults and children. High between-subject variability was determined in the majority of the models, which was in line with the variability of linezolid concentrations previously detected in observational studies. Some studies found that patients with renal impairment, hepatic failure, advanced age, or low body weight had higher exposure and adverse reactions rates. In contrast, lower concentrations and therapeutic failure were associated with obese patients, young patients, and patients who had undergone renal replacement techniques. In critically ill patients, the inter-individual and intra-individual variability was even greater, suggesting that this population is at an even higher risk of underexposure and overexposure. Therapeutic drug monitoring may be warranted in a large proportion of patients given that the Monte Carlo simulations demonstrated that the one-size-fits-all labeled dosing of 600 mg every 12 h could lead to toxicity or therapeutic failure for high values of the minimum inhibitory concentration of the target pathogen. Further research on covariates, including renal function, hepatic function, and drug–drug interactions related to P-glycoprotein could help to explain variability and improve linezolid dosing regimens.

Dosage Strategy of Linezolid According to the Trough Concentration Target and Renal Function in Chinese Critically Ill Patients

Background: Linezolid is associated with myelosuppression, which may cause failure in optimally treating bacterial infections. The study aimed to define the pharmacokinetic/toxicodynamic (PK/TD) threshold for critically ill patients and to identify a dosing strategy for critically ill patients with renal insufficiency.

Methods: The population pharmacokinetic (PK) model was developed using the NONMEM program. Logistic regression modeling was conducted to determine the toxicodynamic (TD) threshold of linezolid-induced myelosuppression. The dosing regimen was optimized based on the Monte Carlo simulation of the final model.

Results: PK analysis included 127 linezolid concentrations from 83 critically ill patients at a range of 0.25–21.61 mg/L. Creatinine clearance (CrCL) was identified as the only covariate of linezolid clearance that significantly explained interindividual variability. Thirty-four (40.97%) of the 83 patients developed linezolid-associated myelosuppression. Logistic regression analysis showed that the trough concentration (Cmin) was a significant predictor of myelosuppression in critically patients, and the threshold for Cmin in predicting myelosuppression with 50% probability was 7.8 mg/L. The Kaplan–Meier plot revealed that the overall median time from the initiation of therapy to the development of myelosuppression was 12 days. Monte Carlo simulation indicated an empirical dose reduction to 600 mg every 24 h was optimal to balance the safety and efficacy in critically ill patients with CrCL of 30–60 ml/min, 450 mg every 24 h was the alternative for patients with CrCL &lt;30 ml/min, and 600 mg every 12 h was recommended for patients with CrCL ≥60 ml/min.

Conclusion: Renal function plays a significant role in linezolid PKs for critically ill patients. A dose of 600 mg every 24 h was recommended for patients with CrCL &lt;60 ml/min to minimize linezolid-induced myelosuppression.

Current pharmacotherapy for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia

INTRODUCTION

Currently, several antibiotics are active against methicillin-resistant Staphylococcus aureus (MRSA) and can be used for the treatment of pneumonia. They show great variability in terms of antibiotic class, indication, pharmacodynamic/pharmacokinetic properties, type of available formulations, spectrum of activity against bacteria other than MRSA, and toxicity profile.

AREAS COVERED

In this narrative review, the authors discuss the characteristics of currently available agents for the treatment of MRSA pneumonia.

EXPERT OPINION

The availability of different agents with anti-MRSA activity, and approved for the treatment of pneumonia can allow a personalized approach for any given patient based on the severity of the disease, the setting of occurrence, the patient's baseline risk of toxicity and drug interactions, and the possibility of oral therapy whenever early discharge or outpatient treatment are possible. Although some gray areas still remain, like the lack of high certainty evidence on the efficacy of some old agents and on the precise role of companion agents with toxin inhibitory activity in the case of necrotizing pneumonia, the frequent availability of different treatment choices, each with peculiar characteristics, is already allowing an important step toward a precision medicine approach for the treatment of MRSA pneumonia.

Model Based Identification of Linezolid Exposure-toxicity Thresholds in Hospitalized Patients

Evidence supports linezolid therapeutic drug monitoring as the exposure-response relationship has been identified for toxicity among patients receiving linezolid, but the data to establish the upper limit are limited and the published toxicity thresholds range widely. The purpose of this study was to determine the linezolid exposure-toxicity thresholds to improve the safety of linezolid. This is a multicenter retrospective study of adult patients treated with linezolid from 2018 to 2019. The population pharmacokinetic model of linezolid was established based on 270 plasma concentrations in 152 patients, which showed creatinine clearance and white cell count are covariates affecting the clearance of linezolid, and serum albumin is the covariate affecting the volume of distribution. Classification and regression tree analysis was used to determine the linezolid exposure thresholds associated with an increased probability of toxicity. Among 141 patients included for toxicity analysis, the rate of occurring toxicity was significantly higher among patients with an AUC_{0-24, d1} ≥163 mg h/L, AUC_{0-24, d2} ≥207 mg h/L, AUC_{0-24, ss} ≥210 mg h/L, and C_min,d2 ≥6.9 mg/L, C_min,ss ≥6.9 mg/L, while no threshold was discovered for C_{min, d1}. Those exposure thresholds and duration of linezolid treatment were independently associated with linezolid-related toxicity in the logistic regression analyses. In addition, the predictive performance of the AUC_0-24 and C_min thresholds at day 2 and steady state were close. Considering that the AUC estimation is cumbersome, C_min threshold at 48 h and steady state with a value of ≥6.9 mg/L is recommended to improve safety, especially for patients with renal insufficiency and patients with low serum albumin.

Presence of Listeria monocytogenes in Ready-to-Eat Meat Products Sold at Retail Stores in Costa Rica and Analysis of Contributing Factors

ABSTRACT

Listeria monocytogenes is a pathogenic bacterium associated with ready-to-eat (RTE) meat products sold at the retail level. The objective of this research was to determine the prevalence of L. monocytogenes in RTE meat products sold at retail in Costa Rica and to study the factors associated with the levels of contamination; analyzed factors include hygienic practices within stores (cutting techniques and microbial contamination of products) and the behavior of the isolates (persistence against antimicrobials and transfer potential). A total of 190 samples of RTE meat products were collected and analyzed for the presence of coliforms and Listeria spp. Isolates of L. monocytogenes were then evaluated in terms of resistance to disinfectants (quaternary ammonium compound [QAC] and chlorine) and their transfer potential from food contact surfaces (knife and cutting boards). Overall Listeria spp. prevalence was 37.4% (71 of 190); Listeria innocua was present in 32.1% (61 of 190) of the products, and L. monocytogenes was found in just 2.6% (5 of 190) of the samples. Most contaminated samples were cut with a knife at the moment of purchase (44.2%). When analyzing practices within the stores, it was observed that L. monocytogenes transfer from inoculated knife to salchichón was higher for samples cut at the beginning of the experiment. In addition, L. monocytogenes transfer from inoculated cutting boards was independent of the number of slices but contamination from plastic was higher than wood. Regarding L. monocytogenes resistance to disinfectants, average reductions of 2.6 ± 1.1 log CFU/mL were detected after 6 min of exposure to 200 ppm of chlorine; however, chlorine resistance varied among the strains. Prevalence of L. monocytogenes in RTE meat products sold at retail could be associated with handling practices within the stores; further studies are necessary to estimate the impact of these practices on the overall risk for consumers.

HIGHLIGHTS

A risk factor-based predictive model for linezolid-induced anaemia: A 7-year retrospective study

WHAT IS KNOWN AND OBJECTIVE

The primary adverse reaction of linezolid is haematological toxicity, leading to thrombocytopenia and anaemia. This study aimed to investigate the risk factors of linezolid-induced anaemia (LI-AN) and establish a predictive model by multivariate logistic regression model analysis to predict LI-AN risks in Chinese adult patients.

METHODS

Demographic and clinical data of patients who underwent linezolid therapy for more than three days between January 2014 and December 2020 in Zhongshan Hospital, Fudan University, were retrieved from the hospital's electronic medical record for analysis. Multivariate logistic regression analysis was employed to establish a predictive model, whose predictability was further evaluated by the area under the receiver operating characteristic (ROC) curve.

RESULTS AND DISCUSSION

The study comprised 298 patients among the 2322 patients who underwent linezolid treatment between 2014 and 2020. Among the 298 patients, 32 (10.7%) developed anaemia with an average of 11.4 (SD 6.2) days after the initiation of linezolid therapy. Multivariate logistic analysis revealed that age ≥60 years (odds ratio [OR] 2.815, 95% confidence interval [CI] 1.242-6.379), higher total bilirubin (TBi) (OR 1.031, 95% CI 1.011-1.051), eGFR < 60 ml/(min·1.73 m² ) (OR 2.537, 95% CI 1.054-6.106), duration of linezolid therapy (DLT) (OR 1.091, 95% CI 1.023-1.163) and intensive care unit (ICU) admittance (OR 2.664, 95% CI 1.150-6.174) were the independent risk factors for anaemia occurrence among patients receiving linezolid therapy. A logistic regression equation based on the five risk factors was subsequently established and transformed to obtain the calculation formula of the combined predictor: Y_{(Combined predictor)}  = X_TBi  + 34.5 × X_Age≥60  + 31.1 × X_eGFR<60  + 32.7 × X_ICU  + 2.9 × X_DLT , (where Age ≥60 years, yes = 1, no = 0; eGFR < 60 ml/(min·1.73 m² ), yes = 1, no = 0; ICU admittance, yes = 1, no = 0). The area under the ROC curve of the combined predictors equation was 0.773 with an optimal cut-off point value of 92.4, corresponding to a 75.0% sensitivity and 76.7% specificity.

WHAT IS NEW AND CONCLUSION

LI-AN is associated with age (≥60 years), higher TBi, eGFR < 60 ml/(min·1.73 m² ), DLT and ICU admittance. Physicians should thus calculate the combined predictor value at the beginning of linezolid treatment to predict and evaluate the risk of LI-AN. An optimal cut-off value larger than 92.4 indicates that the patient has a higher LI-AN risk. As such, Hb levels should be monitored regularly, and dosage regimens adjusted accordingly to prevent anaemia occurrence. This study provides an evidence-based logistic model that reduces LI-AN incidences and promotes the safe clinical use of linezolid.

Effect of renal function on the risk of thrombocytopenia in patients receiving linezolid therapy: a systematic review and meta-analysis

Aims

The association of renal function and linezolid‐induced thrombocytopaenia (LIT) remains controversial. We performed a meta‐analysis to determine whether impaired renal function is associated with an increased LIT risk.

Methods

We conducted a systematic search of PubMed, EMBASE and the Cochrane Library from inception to February 2021 for eligible studies evaluating the relationship between renal function and LIT. Indicators of renal function included renal impairment (RI), severe RI, haemodialysis status, creatinine clearance rate (Ccr) and estimated glomerular filtration rate (eGFR). Unadjusted and adjusted estimates and 95% confidence intervals (CIs) were calculated separately using a random‐effect model.

Results

A total of 24 studies with 3580 patients were included in the meta‐analysis. RI patients had an increased LIT risk compared to non‐RI patients in both the unadjusted (OR 3.54; 95% CI 2.27, 5.54; I² = 77.7%) and adjusted analyses (OR 2.51; 95% CI 1.82, 3.45; I² = 17.9%). This association persisted in the subset of studies involving only patients receiving a fixed conventional dose (600 mg every 12 h) and other subgroup analyses by ethnicity, sample size and study quality. Moreover, the LIT risk was significantly higher in patients with severe RI and haemodialysis than in patients without severe RI and haemodialysis. The eGFR and Ccr were significantly lower in LIT patients than in non‐LIT patients.

Conclusions

Impaired renal function is associated with an increased risk of LIT. A reduced linezolid dose may be considered in RI patients at a low risk of treatment failure, ideally guided by therapeutic drug monitoring.

Initially Reduced Linezolid Dosing Regimen to Prevent Thrombocytopenia in Hemodialysis Patients

This retrospective cohort study investigated the effects of an initially reduced linezolid dosing regimen in hemodialysis patients through therapeutic drug monitoring (TDM). Patients were divided into two groups depending on their initial dose of linezolid (standard dose of 600 mg every 12 h or initially reduced dose of 300 mg every 12 h/600 mg every 24 h). The cumulative incidence rates of thrombocytopenia and severe thrombocytopenia were compared between both groups using the Kaplan-Meier method and log-rank test. Eleven episodes of 8 chronic hemodialysis patients were included; 5 were in the initially reduced-dose group. Thrombocytopenia developed in 81.8% of patients. The cumulative incidence rates of thrombocytopenia and severe thrombocytopenia in the initially reduced-dose group were significantly lower than in the standard-dose group (p < 0.05). At the standard dose, the median linezolid trough concentration (C_min) just before hemodialysis was 49.5 mg/L, and C_min at the reduced doses of 300 mg every 12 h and 600 mg every 24 h were 20.6 mg/L and 6.0 mg/L, respectively. All five episodes underwent TDM in the standard-dose group required dose reduction to 600 mg per day. Our findings indicate that initial dose reduction should be implemented to reduce the risk of linezolid-induced thrombocytopenia among hemodialysis patients.

External Evaluation of Population Pharmacokinetics and Pharmacodynamics in Linezolid-Induced Thrombocytopenia: The Transferability of Published Models to Different Hospitalized Patients

BACKGROUND

The objective of this study was to perform an external evaluation of published linezolid population pharmacokinetic and pharmacodynamic models, to evaluate the predictive performance using an independent data set. Another aim was to offer an elegant environment for display and simulation of both the concentration and platelet count after linezolid administration.

METHODS

We performed a systematic literature search in PubMed for all studies evaluating the population pharmacokinetic and pharmacodynamic parameters of linezolid in patients and selected the models to be used for the external validation. The bias of predictions was visually evaluated by plotting prediction errors (PEs) and relative PEs. The precision of prediction was evaluated by calculating the mean absolute error (MAE), root mean squared error (RMSE), and mean relative error (MRE).

RESULTS

Three articles (models A, B, and C) provided linezolid-induced platelet dynamic models using population pharmacokinetic and pharmacodynamic modeling approaches. The PE and relative PE of both linezolid concentrations and platelet counts for models A and C showed similar predictive distributions. With respect to the prediction accuracy of total linezolid concentration, the MAE, RMSE, and MRE of population prediction values for model C was the smallest. The comparison of the MAE, RMSE, and MRE of patient-individual prediction values for the 3 pharmacodynamic models revealed no large differences.

CONCLUSIONS

We confirmed the transferability of published population pharmacokinetic and pharmacodynamic models and showed that they were suitable for extrapolation to other hospitals and/or patients. This study also introduced application software based on model C for the therapeutic drug monitoring of linezolid.

A systematic review and meta-analysis of myelosuppression in pediatric patients treated with linezolid for Gram-positive bacterial infections

BACKGROUND

The incidence of linezolid-induced myelosuppression in pediatric patients was reported at large difference among prospective studies, with a range of 0-24%. Additionally, there is little study which evaluated the impact of linezolid administration period on myelosuppression in pediatric patients, while it is one of the most frequent reason that linezolid therapy has to be discontinued in adult patients. Here, we performed a systematic review and meta-analysis to reveal the incidence of linezolid-induced thrombocytopenia and anemia, and impact of the administration period of linezolid on myelosuppression based on individual data analysis of pediatric patients.

METHODS

We systematically searched the Scopus, EMBASE, Cochrane Central Register of Controlled Trials, PubMed, and CINAHL until April 2020. We investigated the incidence of linezolid-induced thrombocytopenia and anemia using pooled analysis, and evaluated the impact of linezolid administration period on myelosuppression using meta-analysis.

RESULTS

Thirteen studies with 969 pediatric patients were identified. The pooled incidences of thrombocytopenia and anemia were 9% (95% confidence interval (CI), 3-18%) and 4% (95% CI, 0-12%), respectively. Our meta-analysis showed the extension of linezolid administration period (more than 14 days) resulted in higher incidence of thrombocytopenia (OR 4.86, 95% CI 1.10-21.55) and anemia (OR 4.57, 95% CI 0.13-160.49).

CONCLUSIONS

The incidence of linezolid-induced myelosuppression in pediatric patients was less than 10%. However, our meta-analysis revealed linezolid administration period for more than 14 days was one of risk factors associated with linezolid-induced myelosuppression. Therefore, especially for pediatric patients treated with linezolid for more than 14 days, careful monitoring of myelosuppression is required.

Proposal of initial and maintenance dosing regimens with linezolid for renal impairment patients

Background

Linezolid is administered as a fixed dose to all patients despite evidence of overexposure and thrombocytopenia in renal impairment. The aims of this study were to evaluate the risk of thrombocytopenia and the utility of therapeutic drug monitoring (TDM), and to propose alternate dosing regimens in patients with renal impairment.

Methods

We retrospectively reviewed patients ≥13 years old for whom serum linezolid trough concentration (C_min) was measured during linezolid treatment. Patients with episodes of infection were divided into groups by presence of renal impairment (RI group) or absence of renal impairment (non-RI group), and by use of C_min-based TDM (TDM group) or not (non-TDM group) during linezolid treatment.

Results

In the 108 patients examined by multivariable analyses, renal impairment was independently associated with increased risk of thrombocytopenia (OR 3.17, 95%CI 1.10–9.12) and higher C_min. Analysis of the utility of TDM in the RI group showed that clinical failure rate was significantly lower in the TDM subgroup than in the non-TDM subgroup. Furthermore, in the RI group, dosage adjustments were needed in 90.5% of the TDM subgroup. All episodes administered a reduced dose of 300 mg every 12 h in the RI group showed C_min ≥ 2.0 mg/L. Additional analysis of 53 episodes in which C_min was measured within 48 h after starting administration showed that the initial standard dose for 2 days was sufficient to rapidly reach an effective therapeutic concentration in the RI group.

Conclusions

Empirical dose reduction to 300 mg every 12 h after administration of the initial fixed dose for 2 days and C_min-based TDM may improve safety outcomes while maintaining appropriate efficacy among patients with renal impairment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00479-w.

Classification Tree Analysis Based On Machine Learning for Predicting Linezolid-Induced Thrombocytopenia

Linezolid-induced thrombocytopenia is related to linezolid exposure, baseline platelet count and patient background. Although the relationship usually reflects the time of onset of thrombocytopenia, if the platelet maturation process is taken into account, the platelet decrease can be considered to have started at the beginning of treatment. To predict linezolid-induced thrombocytopenia, classification and regression tree (CART) analysis based on machine learning has been applied to identify predictive factors and cutoff values. We examined 74 patient data with or without linezolid-induced thrombocytopenia. Linezolid concentration and platelet count change, baseline platelet count, age, body weight and creatinine clearance estimate were evaluated as predictive factors for linezolid-induced thrombocytopenia. CART analysis selected the final tree containing two cutoff values: a platelet count reduction to less than 2.3% from baseline at 96 h after the initial dose and a linezolid concentration greater than or equal to 13.5 mg/L at 96 h after the initial dose. The targets for therapeutic intervention were concluded to be the linezolid concentration and the platelet change from baseline at 96 h after the initial dose. These cutoff values occur prior to the onset of thrombocytopenia and should be monitored to avoid linezolid-induced thrombocytopenia.

Analysis of the risk factors of linezolid-related haematological toxicity in Chinese patients

WHAT IS KNOWN AND OBJECTIVES

Haematological toxicity including thrombocytopenia, anaemia and leucopenia is the main adverse events of linezolid (LZD) therapy. This study aimed to investigate the risk factors for LZD-induced haematological toxicity and define the threshold of plasma trough concentration to minimize the haematological toxicity.

METHODS

145 patients who received LZD for more than 10 days were retrospectively reviewed to determine the incidence of LZD-induced haematological toxicity. Meanwhile, the risk factors of haematological toxicity were confirmed by univariate and multivariate logistic regression analysis.

RESULTS AND DISCUSSION

9 (6.2%) patients developed leucopenia, while 52 (35.9%) and 26 (17.9%) patients developed thrombocytopenia and anaemia, respectively. The estimated glomerular filtration rate (eGFR) <90 ml/min/1.73 m² (OR, 2.744; 95% CI, 1.117-6.734; p = 0.028) and baseline platelet count <200 × 10⁹ /L (OR, 6.817; 95% CI, 2.870-16.193; p < 0.0001) were found to be significant risk factors for LZD-related thrombocytopenia. Aspartate aminotransferase (AST) >80 U/L (OR, 4.844; 95% CI, 1.207-19.451; p = 0.026) and eGFR <90 ml/min/1.73 m² (OR, 7.132; 95% CI, 2.088-24.357; p = 0.002) were the risk factors for LZD-related anaemia. However, no significant risk factors were identified for LZD-related leucopenia. Moreover, LZD plasma trough concentration >8 mg/L [OR, 3.047; 95% CI, 1.233-7.539; p = 0.016] could be a predictor for the development of thrombocytopenia and anaemia.

WHAT IS NEW AND CONCLUSION

Hepatic and/or renal dysfunction are the risk factors for LZD-related haematological toxicity, while the target plasma trough concentration within 8 mg/L via dose reduction could minimize the haematological toxicity induced by LZD.

A retrospective test for a possible relationship between linezolid-induced thrombocytopenia and hyponatraemia

WHAT IS KNOWN AND OBJECTIVE

Thrombocytopenia is one of the typical adverse events caused by linezolid (LZD). Recently, some cases of severe hyponatraemia occurring while receiving LZD have been reported. This study investigated a possible relationship between LZD-induced hyponatraemia and thrombocytopenia and identified the risk factors for hyponatraemia and/or thrombocytopenia.

METHODS

In this retrospective, single-centre, observational cohort study, 63 hospitalized patients aged over 18 years who received intravenous injection of LZD for more than seven consecutive days in Oita University Hospital between April 2015 and March 2018 were analysed.

RESULTS

Thrombocytopenia occurred in 25 (39.7%) patients and hyponatraemia in 11 (17.5%) patients. Seven of 11 patients with hyponatraemia had concurrent thrombocytopenia. Although both serum sodium level and platelet count declined in most patients who developed hyponatraemia, no significant association between thrombocytopenia and hyponatraemia was found. Creatinine clearance level (Ccr) was significantly lower not only in the thrombocytopenia (vs no-thrombocytopenia) but also in the hyponatraemia group (vs no-hyponatraemia group). Univariate and multivariate logistic regression analyses identified different risk factors for thrombocytopenia and/or hyponatraemia (thrombocytopenia: Ccr and administration period; hyponatraemia: serum albumin; thrombocytopenia and hyponatraemia: administration period and serum albumin).

WHAT IS NEW AND CONCLUSION

In conclusion, this study found no significant relationship between LZD-induced thrombocytopenia and hyponatraemia and identified some possible risk factors associated with onset of the two adverse events. These require further validation.

Treatment of Necrotizing Soft Tissue Infections: Antibiotics

Necrotizing soft tissue infections (NSTIs) are severe, life-threatening infections, and early therapeutic intervention is essential. Prompt administration of potent antimicrobial agents is pivotal, but inadequate empirical therapy is unfortunately common. Optimization of the antibiotic treatment strategy in NSTIs requires consideration of local epidemiology of causative pathogens and antimicrobial resistance patterns, knowledge on common pathogenetic mechanisms in NSTIs, and adaptations to pharmacokinetic and pharmacodynamic physiological changes in critically ill patients. In the present article we address all these issues, as well as review and compare contemporary guidelines for antimicrobial treatment of NSTIs from around the world.

Risk factor analysis for linezolid-associated thrombocytopenia in critically ill patients

Linezolid is an antibiotic used against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. Its primary adverse effect is haematotoxicity. The objective of this study was to analyse the risk factors for onset of thrombocytopenia in critically ill patients treated with linezolid. This was a retrospective, single-centre study of 72 patients. Platelets were measured from D0 to D20 after the start of treatment. The risk factors for thrombocytopenia were identified using a multivariate logistic regression analysis following a Monte Carlo simulation. Following ROC curve analysis, a baseline platelet count lower than 108 × 10⁹/L and a C_min higher than 4 mg/L, with respective odds ratios of 117 (95% CI [97-206]) and 3 (95% CI [1.5-6.2]) in the simulated population, were identified as risk factors. Among the source population patients combining these 2 factors, a significantly higher number developed thrombocytopenia (66.7% vs. 33.3%, p = 0.0042). A baseline platelet count lower than 108 × 10⁹/L and a C_min higher than 4 mg/L are risk factors for the onset of thrombocytopenia in critically ill patients treated with linezolid.

Reappraisal of Linezolid Dosing in Renal Impairment To Improve Safety

Linezolid is administered as a fixed dose to all patients despite evidence of increased exposure and myelosuppression in renal impairment. The objectives of these studies were to assess the risk of thrombocytopenia with standard-dose linezolid in renal impairment and to identify an alternate dosing strategy. In study 1, data from adult patients receiving linezolid for ≥10 days were retrospectively reviewed to determine the frequency of thrombocytopenia in patients with and without renal impairment. Time-to-event analyses were performed using Cox proportional-hazards models. In study 2, population pharmacokinetic modeling was employed to build covariate-structured models using an independent data set of linezolid concentrations obtained during routine therapeutic drug monitoring (TDM). Monte Carlo simulations were performed to identify linezolid dosing regimens that maximized attainment of therapeutic trough concentrations (2 to 8 mg/liter) across various renal-function groups. Toxicity analysis (study 1) included 341 patients, 133 (39.0%) with renal impairment. Thrombocytopenia occurred more frequently among patients with renal impairment (42.9% versus 16.8%; P < 0.001), and renal impairment was independently associated with this toxicity in multivariable analysis (adjusted hazard ratio [aHR], 2.37; 95% confidence interval [CI], 1.52 to 3.68). Pharmacokinetic analyses (study 2) included 1,309 linezolid concentrations from 603 adult patients. Age, body surface area, and estimated glomerular filtration rate (eGFR) were identified as covariates of linezolid clearance. Linezolid dose reductions improved the probability of achieving optimal exposures in simulated patients with eGFR values of <60 ml/min. Thrombocytopenia occurs more frequently in patients with renal impairment receiving standard linezolid doses. Linezolid dose reduction and trough-based TDM are predicted to mitigate this treatment-limiting toxicity.

The safety of treatment options for acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin-structure infections (ABSSSI) may develop in both in-patients and out-patients, possibly with a severe clinical presentation. Since most phase 3 randomized clinical trials have shown non-inferiority in efficacy across different agents, considerations regarding their different safety profiles inevitably play a crucial role in the everyday choice about which of them should be employed for the treatment of ABSSSI.

AREAS COVERED

In this review, the authors discuss the safety profile of different treatment options for ABSSSI.

EXPERT OPINION

The spread of methicillin-resistant Staphylococcus aureus (MRSA) in the last decades has inevitably influenced the therapeutic approach to ABSSSI. Adequate knowledge of the peculiar toxicity profile of each drug active against MRSA is essential for guiding, monitoring and managing adverse events, in turn reducing any unfavorable impact of toxicity on patients' outcomes. In the next five years, potential toxicity will play a critical role in establishing the best available therapy for each specific patient, together with consideration regarding the possibility of avoiding hospitalization or allowing a switch from intravenous to oral therapy and early discharge.

Real-Life Frequency of New-Onset Thrombocytopenia during Linezolid Treatment

BACKGROUND

Thrombocytopenia is a well-recognized adverse effect of linezolid; however, the frequency of this adverse effect during therapy has been variable across previous studies, and the associated risk factors are unclear.

OBJECTIVES

To identify the real-life frequency of new-onset thrombocytopenia due to linezolid and to determine the associated risk factors.

METHODS

A retrospective observational cohort study was conducted among consecutive inpatients at a tertiary care hospital who received linezolid for a minimum of 5 days between January 2013 and August 2017. Data were extracted from electronic medical records obtained from a hospital database. Thrombocytopenia was defined as platelet count less than 100 × 10⁹/L or a 50% reduction from baseline (i.e., before linezolid initiation). Risk factors were identified by comparing the characteristics of patients who experienced the adverse effect during linezolid therapy with those of patients who did not experience the adverse effect. Continuous data were analyzed with the t test and categorical data with the χ² test.

RESULTS

A total of 102 patients were included (38 women, 64 men; overall mean age 50 years, standard deviation [SD] 21). The mean duration of linezolid therapy was 14 (SD 10) days. Thrombocytopenia occurred in 18 patients (17.6%). Risk factors for the development of thrombocytopenia included mean duration of therapy (22 [SD 18] days versus 12 [SD 7] days; p = 0.023), renal replacement therapy (17% versus 4%; p = 0.032), renal impairment (61% versus 32%; p = 0.021), and concomitant administration of unfractionated heparin (50% versus 21%; p = 0.013).

CONCLUSIONS

The real-life frequency of new-onset of thrombocytopenia in patients receiving linezolid for a minimum of 5 days was 17.6%. Risk factors for linezolid-induced thrombocytopenia included prolonged duration of therapy, renal impairment, and concomitant unfractionated heparin.

Linezolid-induced pure red cell aplasia: a case report and literature review

Linezolid (LZD) is the first oxazolidinone with excellent safety and efficacy profiles against refractory infections caused by gram-positive organisms. Hematological toxicities such as thrombocytopenia, anemia, and leukocytopenia are common in LZD therapy; however, LZD-induced pure red cell aplasia (PRCA) is rare. An 83-year-old man diagnosed with pleural empyema caused by Staphylococcus aureus received LZD after developing resistance to multiple antibiotics. Although his infection-related symptoms were improved by LZD, progressive anemia was noticed after LZD therapy was initiated. Eight weeks after LZD administration began, his hemoglobin level was 5.7 g/dL and reticulocyte proportion was 0.36%, while his white blood cell and platelet counts remained unchanged since admission. Bone marrow examination revealed markedly decreased erythropoiesis with cytoplasmic vacuolation of erythroblasts. Anemia resolved by 14 days after cessation of LZD. It is important to increase the awareness among clinicians about the potential for the hematological effects associated with LZD, particularly for older patients with pre-existing anemia and treatment courses longer than 14 days. To detect bone marrow suppression, including PRCA, we suggest monitoring the complete blood count and reticulocyte count periodically in patients receiving long-term LZD therapy.

Linezolid-induced thrombocytopenia increases mortality risk in intensive care unit patients, a 10 year retrospective study

WHAT IS KNOWN AND OBJECTIVE

Linezolid-induced thrombocytopenia is one of the many confounding conditions in critically ill patients. It is rare but prognostic importance of linezolid-induced thrombocytopenia in ICU population has not been well investigated. The study is to assess the incidence and risk factors of linezolid-induced thrombocytopenia in ICU patients.

METHODS

We conducted a retrospective study with ICU patients treated with linezolid between January 2005 and December 2015 at the adult medical, surgical, emergency, and neurological ICUs at 1500-bed tertiary university medical center.

RESULTS AND DISCUSSION

There were 60 patients (mean age: 69.8 ± 11.9), 29 (48.3%) who developed linezolid-induced thrombocytopenia determined by the Naranjo algorithm on a case-by-case basis during the study period. The patients with linezolid-induced thrombocytopenia had a higher rate of any malignancy (41.4% vs 9.7%, P = 0.007), elevated baseline creatinine levels (median [interquartile range; IQR]: 1.7 mg/dL [0.9-2.5] vs 0.9 mg/dL [0.6-1.3]; P = 0.042), and lower baseline platelet counts (median [IQR] 160 × 10⁹ /L [128-230] vs 194 × 10⁹ /L [118-285]; P = 0.296) than patients without linezolid-induced thrombocytopenia. The patients who developed thrombocytopenia received more platelet transfusions (34.5% vs 6.5%, P = 0.009) and had higher ICU mortality rates (62.1% vs 32.3%, P = 0.037). Logistic regression analysis revealed the following significant risk factors for linezolid-induced thrombocytopenia: presence of any malignancy (odds ratio; OR [95% confidence interval; CI]: 8.667 [1.986-37.831]) and an elevated baseline serum creatinine level (OR: 1.673, CI: 1.046-2.675]).

WHAT IS NEW AND CONCLUSION

Critically ill patients with any malignancy or an elevated baseline creatinine level who were treated with linezolid in the ICU were more likely to develop thrombocytopenia. More importantly, mortality increased with patients who developed linezolid-induced thrombocytopenia compared to those did not.

Evaluation of reporting quality for observational studies using routinely collected health data in pharmacovigilance

OBJECTIVES

To appraise the reporting quality of studies which concerned linezolid-related thrombocytopenia referring to REporting of studies Conducted using Observational Routinely collected health Data (RECORD) statement.

METHODS

Medline, Embase, Cochrane library and clinicaltrial.gov were searched for observational studies concerning linezolid-related thrombocytopenia using routinely collected health data from 2000 to 2017. Two reviewers screened potential eligible articles and extracted data independently. Finally, reporting quality assessment was performed by two senior researchers using RECORD statement.

RESULTS

Of 25 included studies, 11 (44.0%) mentioned the type of data in the title and/or abstract. In 38 items derived from RECORD statement, the median number of items reported in the included studies was 22 (inter-quartile range 18-27). Inadequate reporting issues were discovered in the following aspects: validation studies of the codes or algorithms, study size estimation, quantitative variables, subgroup statistical methods, missing data, follow-up/matching or sampling strategy, sensitivity analysis and cleaning methods, funding and role of funders and accessibility of protocol, raw data.

CONCLUSION

This study provides the evidence that the reporting quality of post-marketing safety evaluation studies conducted using routinely collected health data was often insufficient. Future stakeholders are encouraged to endorse the RECORD guidelines in pharmacovigilance.

Peritoneal dialysis-related peritonitis: challenges and solutions

Peritoneal dialysis is an effective treatment modality for patients with end-stage renal disease. The relative use of peritoneal dialysis versus hemodialysis varies widely by country. Data from a 2004 survey reports the percentage of patients with end-stage renal disease treated with peritoneal dialysis to be 5%-10% in economically developed regions like the US and Western Europe to as much as 75% in Mexico. This disparity is probably related to the availability and access to hemodialysis, or in some cases patient preference for peritoneal over hemodialysis. Peritoneal dialysis-related peritonitis remains the major complication and primary challenge to the long-term success of peritoneal dialysis. Fifty years ago, with the advent of the Tenckhoff catheter, patients averaged six episodes of peritonitis per year on peritoneal dialysis. In 2016, the International Society for Peritoneal Dialysis proposed a benchmark of 0.5 episodes of peritonitis per year or one episode every 2 years. Despite the marked reduction in peritonitis over time, peritonitis for the individual patient is problematic. The mortality for an episode of peritonitis is 5% and is a cofactor for mortality in another 16% of affected patients. Prevention of peritonitis and prompt and appropriate management of peritonitis is essential for the long-term success of peritoneal dialysis in all patients. In this review, challenges and solutions are addressed regarding the pathogenesis, clinical features, diagnosis, treatment, and prevention of peritoneal dialysis-related peritonitis from the viewpoint of an infectious disease physician.

Comparison of Empiric Antibiotics for Acute Osteomyelitis in Children

OBJECTIVES

Broad-spectrum antibiotics are commonly used for the empiric treatment of acute hematogenous osteomyelitis and often target methicillin-resistant Staphylococcus aureus (MRSA) with medication-associated risk and unknown treatment benefit. We aimed to compare clinical outcomes among patients with osteomyelitis who did and did not receive initial antibiotics used to target MRSA.

METHODS

A retrospective cohort study of 974 hospitalized children 2 to 18 years old using the Pediatric Health Information System database, augmented with clinical data. Rates of hospital readmission, repeat MRI and 72-hour improvement in inflammatory markers were compared between treatment groups.

RESULTS

Repeat MRI within 7 and 180 days was more frequent among patients who received initial MRSA coverage versus methicillin-sensitive S aureus (MSSA)-only coverage (8.6% vs 4.1% within 7 days [P = .02] and 12% vs 5.8% within 180 days [P < .01], respectively). Ninety- and 180-day hospital readmission rates were similar between coverage groups (9.0% vs 8.7% [P = .87] and 10.9% vs 11.2% [P = .92], respectively). Patients with MRSA- and MSSA-only coverage had similar rates of 72-hour improvement in C-reactive protein values, but patients with MRSA coverage had a lower rate of 72-hour white blood cell count normalization compared with patients with MSSA-only coverage (4.2% vs 16.4%; P = .02).

CONCLUSIONS

In this study of children hospitalized with acute hematogenous osteomyelitis, early antibiotic treatment used to target MRSA was associated with a higher rate of repeat MRI compared with early antibiotic treatment used to target MSSA but not MRSA. Hospital readmission rates were similar for both treatment groups.

Surveillance of listeriosis in the Tel Aviv District, Israel, 2010-2015

This study analyses the epidemiologic, clinical and molecular findings of all culture-confirmed cases of listeriosis notified from 2010 to 2015 in the Tel Aviv District, which is known to have high rates of listeriosis. All clinical isolates of Listeria monocytogenes were subtyped using two-enzyme pulsed-field gel electrophoresis. During the studied period, 102 cases of listeriosis were notified, including 23 pregnancy-associated cases (23%). Among 79 non-pregnancy-associated cases, 18 had neuro-invasive disease (21%). There were 26 deaths associated with the disease. Using molecular identification, we found a number of clusters of identical bacterial clones, which pointed to possible sources of infection. The high rates of morbidity and mortality resulting from listeriosis, as well as the diverse ways of infection demonstrated in this study, accentuate the need to boost public health actions, in order to raise awareness and better control high-risk contamination routes.

Perioperative body weight change is associated with in-hospital mortality in cardiac surgical patients with postoperative acute kidney injury

Background

Postoperative acute kidney injury (AKI) is common following cardiac surgery (CS). Body weight (BW) may be an amenable variable by representing the summation of the nutritional and the fluid status. However, the predictive role of perioperative BW changes in CS patients with severe postoperative AKI is never explored. This study aimed to evaluate this association.

Methods

This study was conducted using a prospectively collected multicenter cohort, NSARF (National Taiwan University Hospital Study Group on Acute Renal Failure) database. The adult CS patients with postoperative AKI requiring renal replacement therapy (RRT), who had clear initial consciousness, received CS within 14 days of hospitalization, and underwent RRT within seven days after CS in intensive care units from January 2001 to January 2014 were enrolled. With the endpoint of 30-day postoperative mortality, we evaluated the association between the clinical factors denoting fluid status and patients outcomes.

Results

A total of 188 patients (70 female, mean age 63.7 ± 15.2 years) were enrolled. Comparing with the survivors (n = 124), the non-survivors (n = 64) had a significantly higher perioperative BW change [3.6 ± 6.1% versus 0.1 ± 8.3%, p = 0.003] but not the postoperative and pre-RRT BW changes. By using multivariate Cox proportional hazards model, the independent indicators of 30-day postoperative mortality included perioperative BW change (p = 0.026) and packed red blood cells transfusion (p = 0.007), postoperative intra-aortic balloon pump (p = 0.001) and central venous pressure level (p = 0.005), as well as heart rate (p = 0.022), sequential organ failure assessment score (p < 0.001), logistic organ dysfunction score (p = 0.001), and blood total bilirubin level (p = 0.044) at RRT initiation. The generalized additive models further demonstrated, in a multivariate manner, that the mortality risk rose significantly during a perioperative BW change of 2% to 15%.

Conclusions

Perioperative BW change was independently associated with an increased risk for 30-day postoperative mortality in CS patients with RRT-requiring AKI.

Population pharmacokinetics and pharmacodynamics of linezolid-induced thrombocytopenia in hospitalized patients

AIMS

Thrombocytopenia is among the most important adverse effects of linezolid treatment. Linezolid-induced thrombocytopenia incidence varies considerably but has been associated with impaired renal function. We investigated the pharmacodynamic mechanism (myelosuppression or enhanced platelet destruction) and the role of impaired renal function (RF) in the development of thrombocytopenia.

METHODS

The pharmacokinetics of linezolid were described with a two-compartment distribution model with first-order absorption and elimination. RF was calculated using the expected creatinine clearance. The decrease platelets by linezolid exposure was assumed to occur by one of two mechanisms: inhibition of the formation of platelets (PDI) or stimulation of the elimination (PDS) of platelets.

RESULTS

About 50% of elimination was found to be explained by renal clearance (normal RF). The population mean estimated plasma protein binding of linezolid was 18% [95% confidence interval (CI) 16%, 20%] and was independent of the observed concentrations. The estimated mixture model fraction of patients with a platelet count decreased due to PDI was 0.97 (95% CI 0.87, 1.00), so the fraction due to PDS was 0.03. RF had no influence on linezolid pharmacodynamics.

CONCLUSION

We have described the influence of weight, renal function, age and plasma protein binding on the pharmacokinetics of linezolid. This combined pharmacokinetic, pharmacodynamic and turnover model identified that the most common mechanism of thrombocytopenia associated with linezolid is PDI. Impaired RF increases thrombocytopenia by a pharmacokinetic mechanism. The linezolid dose should be reduced in RF.

Nationwide epidemiology and prognosis of dialysis-requiring acute kidney injury (NEP-AKI-D) study: Design and methods

AIM

Acute kidney injury (AKI) carries an increasing incidence rate worldwide and increases the risk of developing end-stage renal disease (ESRD) as well as the medical expenses during the post-AKI course. The Taiwan Consortium for Acute Kidney Injury and Renal Diseases (CAKs) has thus launched a nationwide epidemiology and prognosis of dialysis-requiring acute kidney injury (NEP-AKI-D) study, which prospectively enrols critically ill patients with AKI. Through thoroughly evaluating the risk and prognostic factors of AKI, we hope to lower the incidence of AKI and ESRD from the perspective of AKI-ESRD interaction.

METHODS

The CAKs includes 30 hospitals which distribute widely through the four geographical regions (north, middle, south, and east) of Taiwan, and have a 1:1 ratio of medical centres to regional hospitals in each region. The NEP-AKI-D study enrols intensive care unit-based AKI patients who receive dialysis in the four seasonal sampled months (October 2014, along with January, April, and July 2015) in the included hospitals. The collected data include demographic information, pertaining laboratory results, dialysis settings and patient outcomes. The data are uploaded in a centre website and will be audited by on-site principal investigators, computer logic gates, and the CAKs staffs. The outcomes of interest are in-hospital mortality, dialysis-dependency and readmission rate within 90 days after discharge.

CONCLUSION

The NEP-AKI-D study enrols a large number of representative AKI patients throughout Taiwan. The results of the current study are expected to provide more insight into the risk and prognostic factors of AKI and further attenuated further chronic kidney disease transition.