Severe thrombocytopenia caused by linezolid poisoning in an underweight critically ill patient with renal impairment treated with the recommended doses

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.

Novel Population Pharmacokinetic Model for Linezolid in Critically Ill Patients and Evaluation of the Adequacy of the Current Dosing Recommendation

Antimicrobial treatment in critically ill patients remains challenging. The aim of this study was to develop a population pharmacokinetic model for linezolid in critically ill patients and to evaluate the adequacy of current dosing recommendation (600 mg/12 h). Forty inpatients were included, 23 of whom were subjected to continuous renal replacement therapies (CRRT). Blood and effluent samples were drawn after linezolid administration at defined time points, and linezolid levels were measured. A population pharmacokinetic model was developed, using NONMEM 7.3. The percentage of patients that achieved the pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated (AUC₂₄/MIC > 80 and 100% T_>MIC). A two-compartment model best described the pharmacokinetics of linezolid. Elimination was conditioned by the creatinine clearance and by the extra-corporeal clearance if the patient was subjected to CRRT. For most patients, the standard dose of linezolid did not cover infections caused by pathogens with MIC ≥ 2 mg/L. Continuous infusion may be an alternative, especially when renal function is preserved.

A Case of Linezolid Toxicity Presenting as a Sepsis Mimic

Linezolid is an efficacious and well tolerated antimicrobial but can have serious adverse effects including myelo-suppression, serotonin syndrome, neuropathy, hypoglycemia, liver dysfunction, and lactic acidosis. The side effects are generally duration dependent; linezolid use is not recommended for more than 28 days. Case. A 59-year-old female presented with malaise, loss of appetite, and altered mentation. She had multiple medical comorbidities and required long-term anticoagulation with warfarin for venous thromboembolism. She had multiple medication allergies. Prior to admission, she was on linezolid for cellulitis of foot due to Methicillin-resistant Staphylococcus aureus (MRSA). On physical exam, she was drowsy and required endotracheal intubation for airway protection. Initial laboratory parameters showed lactic acidosis, thrombocytopenia, supra-therapeutic coagulation profile, low blood glucose, and transaminitis. Her altered mentation was due to hypoglycemia. The interaction with warfarin led to altered coagulation profile. She developed shock and vasopressors were initiated. Given her presentation, she was managed as severe sepsis. There were no active infectious foci attributing to decline of her clinical status. Linezolid was discontinued and she was managed with intravenous polymyxin B, aztreonam, and vancomycin. Her hemodynamic status improved within one day. She was extubated on Day 5 of her presentation. Her laboratory parameters showed gradual improvement over 12 days after discontinuation of linezolid. Retrospective evaluation revealed linezolid toxicity as possible cause of presentation. Linezolid toxicity can present as sepsis mimic and should be considered as a differential diagnosis while managing sepsis with other antimicrobial agents.

Analysis of the prevalence and associated factors of overactive bladder in adult Korean men

Overactive bladder (OAB) is a prevalent condition characterized by lower urinary tract symptoms (LUTS). Age, education, income, marital status, sleep, and emotional problems have been associated with OAB; however, conflicting results exist. The present study was conducted to estimate the prevalence of OAB and comprehensively analyze its associated factors in a large cross-sectional, population-based study. The data of 94,554 participants aged 19-107 were analyzed from the Korean Community Health Survey (KCHS) of 2012. Data on marital status, physical activity, education level, occupation, body mass index (BMI), income level, sleep time, and stress level were retrieved for all enrolled participants. The overactive bladder symptom score (OABSS) was used to evaluate the presence and degree of OAB. Simple and multiple logistic regression analyses with complex sampling were used for the associations between various factors and the presence of OAB. Overall, OAB was present in approximately 2.9% of the participants. The prevalence of OAB increased with age and steeply increased after 60 years of age (adjusted odds ratio [AOR] for each 10 years = 1.70, 95% confidence interval [CI] = 1.61-1.80, P<0.001). The prevalence of OAB was lower in married than unmarried subjects (AOR = 0.59, 95% CI = 0.48-0.72, P<0.001). The prevalence of OAB was significantly different according to occupation Compared to manager, expert, specialist, clerk group, the prevalence of OAB was highest in unemployed group (AOR = 1.90, 95% CI = 1.55-2.32, P < 0.001). Being underweight was correlated with OAB (AOR = 1.29, 95% CI = 1.08-1.55, P = 0.018). Inadequate sleep showed a significant association with OAB (AOR = 1.13, 95% CI = 1.02-1.25 for ≤6 hours of sleep time and AOR = 1.53, 95% CI = 1.27-1.86 for ≥9 hours of sleep, P<0.001). Stress level showed a dose-dependent positive association with OAB [AOR (95% CI) = 3.91 (3.13-4.89) > 2.16 (1.88-2.48) > 1.39 (1.23-1.57) for severe stress > moderate stress > some stress, respectively, P<0.001]. A medical history of diabetes mellitus, hyperlipidemia, and/or cerebral stroke was significantly related to OAB. Approximately 2.9% of adult Korean men experienced OAB based on the OABSS. Unmarried status; occupation; being underweight; inadequate sleep; stress; and medical history of diabetes mellitus, hyperlipidemia, or cerebral stroke were significantly correlated with OAB.