"Unmasking a Looming Crisis: Escalating MIC of Last Resort Drugs against MRSA Isolates from a Tertiary Hospital in Central India."

PURPOSE: The Centers for Disease Control and Prevention has classified methicillin-resistant S aureus (MRSA) as a serious public health threat. The escalating minimum inhibitory concentration (MIC) of standard anti-methicillin-resistant S aureus (MRSA) drugs within the susceptible range, known as "MIC creep," jeopardizes their effectiveness against MRSA infections, posing additional challenges in managing MRSA infections. This cross-sectional study was conducted in a tertiary care hospital in Central India to assess the susceptibility trends of clinical MRSA isolates against commonly used anti-MRSA drugs and to observe MIC creep, if any, over three years (2020-2022). METHODS: The study included 158 non-repetitive clinical MRSA isolates. The MICs of vancomycin, teicoplanin, and linezolid were determined in MRSA strains using agar dilution, while the MIC of daptomycin was performed by broth microdilution. MIC creep was assessed by calculating MIC50, MIC90, Modal MIC, G-mean MIC, and susceptible and resistant percentages for the fiscal years 2020, 2021, and 2022. RESULTS: Of the 158 MRSA isolates, none were resistant to vancomycin, teicoplanin, and daptomycin, but two showed resistance to linezolid (LRSA). However, fifteen isolates showed intermediate resistance to vancomycin (VISA), and five showed intermediate resistance to teicoplanin (TISA). MIC of these anti-MRSA drugs increased in 2021 and 2022 compared to 2020. G-mean MIC for vancomycin, teicoplanin, and linezolid in MRSA strains increased significantly over the study period, while daptomycin MIC remained relatively stable, with a slight increase in 2021 and 2022. There was a high resistance rate for clindamycin, doxycycline, and chloramphenicol among VISA, TISA, and LRSA isolates compared to MRSA. CONCLUSIONS: During the three years of the study, "MIC creep" was observed in vancomycin, teicoplanin, and linezolid and, to some extent, for daptomycin in MRSA strains. The recovery of VISA, TISA, and linezolid-resistant MRSAs is worrisome, suggesting possible MRSA treatment failure and being a forerunner of resistant strains.

Increased risk of adverse drug reactions by higher linezolid dose per weight in multidrug-resistant tuberculosis.

Linezolid treatment has a high risk of toxicity and adverse drug reactions (ADR) are frequent. Few studies have investigated risk factors of major ADRs separately, therefore, we aimed to evaluate major ADRs including peripheral neuropathy in relation to risk factors and drug concentration levels of linezolid in a high-resource setting for multidrug-resistant tuberculosis (MDR-TB). We conducted a retrospective cohort study including participants treated with a linezolid-containing MDR-TB regimen in Sweden 1992-2018. Data was collected from medical records. ADRs were classified according to Common Terminology Criteria for Adverse Events (version 5.0). Of all participants (n=132), 43.2% were female and the median age 28 years. The median linezolid treatment was 6.5 months (IQR 3.0-12.7) with a median daily dose of 9.6 mg/kg/day. Any ADR was seen in 58.3% (n=77) of participants, with 35.6% having peripheral neuropathy (n=47), 27.3% anaemia (n=36), 22.0% leukopenia (n=36) while 6.1% (n=8) had optic neuritis. The median time for peripheral neuropathy was 3.6 months (IQR 2.1-5.9) and 8.3 months (6.2-10.7) for optic neuritis. A >2.0 mg/L trough concentration (n=40) was associated with anaemia (p=0.0038) and thrombocytopenia (p=0.009) but not with peripheral neuropathy. In multivariable analysis, a dose ≥12 mg/kg/day was associated with time to peripheral neuropathy (HR 2.89, 95%CI 1.08-7.74, p=0.035), anaemia (HR 6.62, 95%CI 2.22-19.8, p=0.001) and leukopenia (HR 5.23, 95% CI 1.48-18.5, p=0.010). Linezolid ADRs were frequent in a high-resource setting. Structured, regular follow-up for ADRs and adjusting dosing according to body weight followed-up by monitoring of drug concentrations early may reduce toxicity.

Contezolid for the Treatment of Drug-Resistant Tuberculosis in China: A Clinical Case Series.

Background: Linezolid (LZD) is a cornerstone medication in the treatment of drug-resistant tuberculosis (DR-TB). However, it frequently triggers adverse effects such as bone marrow suppression, optic neuropathy, and peripheral neuropathy, all of which can impact treatment outcomes and prognosis. Contezolid (CZD), a novel oxazolidinone antibiotic, exhibits comparable antimicrobial efficacy against Mycobacterium tuberculosis as LZD, but with potentially enhanced safety profiles. Case Presentation: This report presents five cases (Cases 1-5) of LZD intolerance, wherein CZD served as an effective alternative treatment. In Cases 1-3, LZD administration resulted in bone marrow suppression, primarily manifested as anemia. Transitioning to CZD therapy led to a rise and stabilization of hemoglobin (HGB) levels in Cases 1-2, and a return to baseline values in Case 3. In Case 4, CZD treatment alleviated symptoms of LZD-induced peripheral neuritis, although complete resolution was not achieved, hinting at potential irreversibility of this type of peripheral neuropathy. In Case 5, direct CZD anti-TB therapy was initiated for recurrent leukopenia and neutropenia, resulting in no further severe myelosuppression and successful recovery. Conclusion: These case studies suggest that CZD could represent an effective and safe option for anti-TB therapy, especially for patients intolerant to LZD.

Successful treatment of Enterococcus gallinarum infection in a neonate with vancomycin: a case report.

BACKGROUND: Enterococcus gallinarum (EG) is typically found in the gastrointestinal tracts of birds and mammals. Although its strains are rarely isolated from clinical specimens, EG can lead to septicemia in immunocompromised individuals. EG infections are uncommon in household settings, but their incidence has been rising due to increased antibiotic usage and invasive treatments, particularly in Neonatal Intensive Care Units (NICUs). EG inherently exhibits resistance to vancomycin but is highly sensitive to linezolid. Despite showing in vitro resistance, vancomycin has shown clinical efficacy in treating EG meningitis. CASE PRESENTATION: A neonate born at 30 + 2 weeks gestation was admitted to the Neonatal Intensive Care Unit (NICU) after EG was detected in blood and cerebrospinal fluid cultures. Susceptibility testing indicated that the bacterial strain was resistant to vancomycin and sensitive to linezolid. Initially, vancomycin was selected for treatment. However, due to persistent EG cultures in the blood and cerebrospinal fluid, the treatment was adjusted to linezolid. This led to a rapid decrease in platelet (PLT) count, suspected to be an adverse reaction. Concurrently, the patient experienced recurrent fever and elevated inflammatory marker levels, prompting the discontinuation of linezolid and a return to vancomycin. Subsequent administration of vancomycin stabilized the patient's condition, as evidenced by improved C-reactive protein (CRP), procalcitonin (PCT), and cerebrospinal fluid parameters, ultimately leading to discharge after an eight-week treatment period. CONCLUSION: This retrospective analysis highlights the efficacy of vancomycin in treating EG infections, suggesting that specific genetic phenotypes may influence treatment sensitivity. Monitoring vancomycin blood levels is crucial for determining treatment effectiveness.

Pharmacokinetics and Safety of Linezolid Tablets of 2 Different Manufacturers in Healthy Chinese Subjects in Fasting and Fed States.

This study aimed to evaluate the pharmacokinetics (PKs) and safety of a generic drug, linezolid, compared to those of a reference drug in healthy Chinese subjects under both fasting and fed conditions. This was a randomized, open-label, 2-period, 2-sequence crossover study. The subjects received a single dose of the test or reference drug, linezolid (600 mg), in each period. The PK parameters were calculated using a non-compartmental method and compared between the 2 drugs. Bioequivalence was analyzed using geometric mean ratios (GMRs) of the 2 formulations and their corresponding 90% confidence intervals (CIs). The safety of the 2 formulations was assessed under both fasting and fed conditions. Forty-eight subjects completed the study, 24 each in the fasting and feeding groups. The average plasma concentration-time patterns of linezolid were similar for both medications under both conditions. The GMR and 90% CIs of the maximum plasma concentration and the area under the plasma concentration-time curve of linezolid were ranged from 0.80 to 1.25. Both drugs were well tolerated with a similar incidence of adverse drug reactions. In conclusion, the PK and safety profiles of the 2 formulations were comparable. Food intake did not influence the PK profiles of linezolid. These results suggest that the test drug can be used as an alternative to reference drugs.

Facile fabrication of linezolid/strontium coated hydroxyapatite/graphene oxide nanocomposite for osteoporotic bone defect.

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ's physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

Acupuncture as adjunctive treatment for linezolid-induced peripheral neuropathy: a case series report.

Background: The treatment of multidrug-resistant tuberculosis (MDR-TB) and pre-extensively drug-resistant tuberculosis (pre-XDR-TB) remains challenging due to the limited availability of effective drugs. Linezolid has emerged as a promising therapeutic option for these cases. However, its long-term use can lead to complications such as peripheral and optic neuropathies. Acupuncture, a cornerstone of traditional Chinese medicine, has been shown to be effective in the treatment of peripheral neuropathy (PN). This study examines the potential benefits of acupuncture in the treatment of linezolid-induced peripheral neuropathy (LIPN). Methods: Four patients, aged 27 to 60 years, diagnosed with LIPN, underwent daily acupuncture treatments. The main endpoint was to assess the efficacy of acupuncture in reducing neuropathic pain associated with LIPN in patients. This was primarily measured using changes in the Short Form McGill Pain Questionnaire (SF-MPQ) scores before and after acupuncture treatment. Results: Three of the patients experienced significant symptom remission, while one experienced marginal improvement. Treatments ranged from 7 to 18 sessions. Specifically, the first patient reported substantial relief with a score reduction from 33 to 13; the second patient observed minimal change; the third patient's score decreased dramatically from 10 to 2 after eight sessions; the last patient had a score reduction from 21 to 12 after five sessions, but did not continue treatment for a second assessment. Conclusion: Acupuncture is a promising therapeutic approach for LIPN. However, larger and more thorough studies are needed to determine its full potential.

Analysis of molecular epidemiological characteristics and antimicrobial susceptibility of vancomycin-resistant and linezolid-resistant Enterococcus in China.

BACKGROUND: This study investigates the distribution and characteristics of linezolid and vancomycin susceptibilities among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and explores the underlying resistance mechanisms. METHODS: A total of 2842 Enterococcus clinical isolates from patients were retrospectively collected, and their clinical data were further analyzed. The minimum inhibitory concentrations (MICs) of vancomycin and linezolid were validated by broth dilution method. The resistance genes optrA, cfr, vanA, vanB and vanM were investigated using polymerase chain reaction (PCR). Housekeeping genes and resistance genes were obtianed through whole-genome sequencing (WGS). RESULTS: Of the 2842 Enterococcus isolates, 88.5% (2516) originated from urine, with E. faecium accounted for 60.1% of these. The vanA gene was identified in 27/28 vancomycin resistant Enterococcus (VRE) isolates, 4 of which carried both vanA and vanM genes. The remaining strain was vanM positive. The optrA gene was identified in all E. faecalis isolates among linezolid resistant Enterococcus (LRE). E. faecium showed a higher multiple antibiotic resistance index (MAR index) compared to E. faecalis. The multi-locus sequence typing (MLST) showed the sequence type of E. faecium mainly belongs to clonal complex (CC) 17, nearly E. faecalis isolates analyzed were differentiated into 7 characteristics of sequence types (STs), among which ST16 of CC16 were the major lineage. CONCLUSION: Urine was the primary source of VRE and LRE isolates in this study. E. faecium showed higher levels of resistance compared to E. faecalis. OptrA gene was detected in 91.6% of LRE, which could explain linezolid resistance, and van genes were detected in all vancomycin resistant Enterococcus strains, while vanA was a key resistance mechanism in VRE identified in this study.

Development of an HPLC method using relative molar sensitivity for the measurement of blood concentrations of nine pharmaceutical compounds.

We developed a reliable high-performance liquid chromatographic analysis method using a relative molar sensitivity (RMS) technique that does not require an authentic, identical reference analyte material to quantify blood serum carbamazepine, phenytoin, voriconazole, lamotrigine, meropenem, mycophenolic acid, linezolid, vancomycin, and caffeine levels for routine blood concentration measurements. Carbamazepine and caffeine were also used as non-analyte reference materials to calculate the RMS of each analyte. The RMS was calculated from the ratio of the slope of the calibration equation (analyte/non-analyte reference material), then used to quantify analytes in control serum samples spiked with carbamazepine, phenytoin, voriconazole, meropenem, mycophenolic acid, linezolid or vancomycin. In addition, the concentrations of these six drugs in control serum samples determined by the proposed RMS method agreed well with that obtained using a conventional method. The proposed RMS method is a promising tool for the clinical determination of nine drugs, given the accuracy, precision, and efficiency of quantifying these analytes.

Cost and cost-effectiveness of BPaL regimen used in drug-resistant TB treatment in the Philippines.

BACKGROUND: In 2022, the WHO announced that the 6-month BPaL/M regimen should be used for drug-resistant TB (DR-TB). We estimate the patient and provider costs of BPaL compared to current standard-of-care treatment in the Philippines. METHODS: Patients on BPaL under operational research, or 9-11-month standard short oral regimen (SSOR) and 18-21-month standard long oral regimen (SLOR) under programmatic conditions were interviewed using the WHO cross-sectional TB patient cost tool. Provider costs were assessed through a bottom-up and top-down costing analysis. RESULTS: Total patient costs per treatment episode were lowest with BPaL (USD518.0) and increased with use of SSOR (USD825.8) and SLOR (USD1,023.0). Total provider costs per successful treatment were lowest with BPaL (USD1,994.5) and increased with SSOR (USD3,121.5) and SLOR (USD10,032.4). Compared to SSOR, BPaL treatment was cost-effective at even the lowest willingness to pay threshold. As expected, SLOR was the costliest and least effective regimen. CONCLUSIONS: Costs incurred by patients on BPaL were 37% (95% CI 22-56) less than SSOR and 50% (95% CI 32-68) less than SLOR, while providers could save 36% (95% CI 21-56) to 80% (95% CI 64-93) per successful treatment, respectively. The study shows that treatment of DR-TB with BPaL was cost-saving for patients and cost-effective for the health system.

CONTEXTE: En 2022, l'OMS a annoncé que le traitement BPaL/M de 6 mois devrait être utilisé pour la TB pharmacorésistante (DR-TB). Nous estimons les coûts du BPaL pour les patients et les prestataires par rapport au traitement standard actuel aux Philippines. MÉTHODES: Des patients sous BPaL dans le cadre d'une recherche opérationnelle, ou un régime oral court standard de 9 à 11 mois (SSOR, pour l'anglais « standard short oral regimen ¼) et un régime oral long standard de 18 à 21 mois (SLOR, pour l'anglais « standard long oral regimen ¼) dans des conditions programmatiques ont été interrogés à l'aide de l'outil transversal de l'OMS sur le coût pour les patients atteints de TB. Les coûts des fournisseurs ont été évalués par une analyse ascendante et descendante des coûts. RÉSULTATS: Les coûts totaux pour les patients par épisode de traitement étaient les plus bas avec BPaL (518,0 USD) et augmentaient avec l'utilisation de SSOR (825,8 USD) et SLOR (1 023,0 USD). Les coûts totaux des prestataires par traitement réussi étaient les plus bas avec BPaL (1 994,5 USD) et ont augmenté avec SSOR (3 121,5 USD) et SLOR (10 032,4 USD). Comparé à SSOR, le traitement BPaL était rentable même au seuil de volonté de payer le plus bas. Comme prévu, le SLOR était le régime le plus coûteux et le moins efficace. CONCLUSIONS: Les coûts encourus par les patients sous BPaL étaient inférieurs de 37% (IC à 95% 22­56) à ceux du SSOR et de 50% (IC à 95% 32­68) à ceux du SLOR, tandis que les prestataires pouvaient économiser respectivement 36 % (IC à 95% 21­56) à 80% (IC à 95% 64­93) par traitement réussi. L'étude montre que le traitement de la DR-TB par BPaL a permis de réaliser des économies pour les patients et pour le système de santé.

Adverse drug reactions due to linezolid in the programmatic management of drug-resistant tuberculosis in India: A retrospective multicenter study.

BACKGROUND: Monitoring and managing adverse drug reactions (ADR) are critical for treating drug-resistant tuberculosis (TB). OBJECTIVE: To study symptomatic, linezolid-attributable ADRs in TB patients initiated on all oral longer bedaquiline-based treatment regime for multidrug-resistant/rifampicin-resistant (MDR/RR)-TB under programmatic conditions. METHODS: It was a multicenter, retrospective study of people with MDR/RR-TB in nine TB units in Nagpur, India, from March 2020 to April 2022. RESULTS: The study consisted of a sample size of 106 individuals with multidrug-resistant and rifampicin-resistant tuberculosis out of a total of 110 individuals with the disease. Of these, 45 (42.45%) experienced linezolid ADRs, with an incidence of 11.37 cases per 1000 person-weeks. These patients were significantly younger (31.24 ± 11.13 years) and more likely to be female (27, 50%) than those without ADRs. ADR severity was mild in 20 (44.45%), moderate in 15 (33.33%), and severe in 10 (22.22%) patients. The most common ADR was peripheral neuropathy (42, 93.33%), followed by lactic acidosis (3, 6.67%), anemia (2, 4.44%), and optic neuritis (2, 4.44%). Dosing was reduced in 17 (37.78%) patients, and linezolid was withdrawn entirely in 19 (42.22%) patients. Only 9 (20%) patients continued linezolid unmodified. For mild to moderate linezolid-associated symptomatic peripheral neuropathy, symptom management with or without dose reduction is an effective strategy; however, immediate linezolid withdrawal is necessary in severe or life-threatening peripheral neuropathy cases. After a mean follow-up of 41 ± 21.33 weeks, ADR symptoms resolved completely in 4 (6.67%) patients and decreased in 42 (93.33%) patients. CONCLUSION: Linezolid ADRs, often neuropathy, frequently occur in patients on an all-oral bedaquiline-based treatment regime for MDR/RR-TB. Women and younger patients are more likely to experience these ADRs, usually mild to moderate in severity. Management of symptomatic linezolid-associated peripheral neuropathy should be based on ADR severity. These ADRs often affect linezolid dosing, so it is important to identify and manage them early.

Linezolid induced toxic optic neuropathy in drug resistant tuberculosis-A case series.

In developing countries like India, Linezolid is widely used for the treatment of Multi drug resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB). Long-term administration of Linezolid is reported to cause toxic optic neuropathy causing bilateral, progressive visual loss in patients. We report case details of three patients on anti-tubercular therapy presented to us with sudden, progressive, painless blurring of vision of both eyes the cause of which was confirmed to be toxic optic neuropathy due to linezolid. Subsequently, cessation of the drug resulted in complete visual recovery in two patients whereas one patient had minimal visual improvement due to secondary optic atrophy. Clinicians and health care workers need to be aware of sight threatening complications of Linezolid.

The burden of antibiotic resistance of the main microorganisms causing infections in humans - review of the literature.

One of the biggest threats to human well-being and public health is antibiotic resistance. If allowed to spread unchecked, it might become a major health risk and trigger another pandemic. This proves the need to develop antibiotic resistance-related global health solutions that take into consideration microdata from various global locations. Establishing positive social norms, guiding individual and group behavioral habits that support global human health, and ultimately raising public awareness of the need for such action could all have a positive impact. Antibiotic resistance is not just a growing clinical concern but also complicates therapy, making adherence to current guidelines for managing antibiotic resistance extremely difficult. Numerous genetic components have been connected to the development of resistance; some of these components have intricate paths of transfer between microorganisms. Beyond this, the subject of antibiotic resistance is becoming increasingly significant in medical microbiology as new mechanisms underpinning its development are identified. In addition to genetic factors, behaviors such as misdiagnosis, exposure to broad-spectrum antibiotics, and delayed diagnosis contribute to the development of resistance. However, advancements in bioinformatics and DNA sequencing technology have completely transformed the diagnostic sector, enabling real-time identification of the components and causes of antibiotic resistance. This information is crucial for developing effective control and prevention strategies to counter the threat.

Genomic analysis of enterococci carrying optrA, poxtA, and vanA resistance genes from wild boars, Italy.

AIMS: To investigate enterococci carrying linezolid and vancomycin resistance genes from fecal samples recovered from wild boars. METHODS AND RESULTS: Florfenicol- and vancomycin-resistant enterococci, isolated on selective agar plates, were screened by PCR for the presence of linezolid and vancomycin resistance genes. Five isolates carried optrA or poxtA linezolid resistance genes; one strain was resistant to vancomycin for the presence of vanA gene. All isolates were tested for their antibiotic susceptibility and subjected to Whole Genome Sequencing (WGS) analysis. In Enterococcus faecalis (E. faecalis) V1344 and V1676, the optrA was located on the new pV1344-optrA and pV1676-optrA plasmids, respectively, whereas in Enterococcus faecium (E. faecium) V1339 this gene was on a 22 354-bp chromosomal genetic context identical to the one detected in a human E. faecium isolate. In both E. faecium V1682 and E. durans V1343, poxtA was on the p1818-c plasmid previously found in a human E. faecium isolate. In E. faecium V1328, the vanA gene was on the Tn1546 transposon in turn located on a new pV1328-vanA plasmid. Only E. faecium V1682 successfully transferred the poxtA gene to an enterococcal recipient in filter mating assays. CONCLUSIONS: The occurrence of genetic elements carrying linezolid and vancomycin resistance genes in enterococci from wild boars is a matter of concern, moreover, the sharing of plasmids and transposons between isolates from wild animals, human, and environment indicates an exchange of genetic material between these settings.

Efficacy of linezolid in the treatment of tuberculous meningitis: a meta-analysis.

Introduction: Tuberculous meningitis (TBM) is a severe extra-pulmonary tuberculosis with high fatality. This meta-analysis aimed to assess the impact of linezolid on TBM treatment outcomes. Methods: We searched multiple databases for studies published up to May 18, 2024 comparing the effects of linezolid on TBM. Meta-analysis was conducted using Review Manager 5.4. Results: Our findings indicated that linezolid may reduce treatment failure risk (RR = 0.42 (0.20, 0.89), p = 0.02) and improve temperature recovery (RR = 1.56 (1.21, 2.02), p < 0.001) in TBM patients. Conclusions: The analysis suggests a positive association between linezolid treatment and therapeutic improvements, with no significant adverse reactions reported.

Clinical drug interactions between linezolid and other antibiotics: For adverse drug event monitoring.

Detailed data on safety associated with drug-drug interactions (DDIs) between Linezolid (LZD) and other antibiotics are limited. The aim of this study was to investigate the safety signals related to these DDIs and to provide a reference for clinically related adverse drug event monitoring. Adverse event (AE) information from 1 January 2004 to 16 June 2022 of the target antibiotics including LZD using alone or in combination with LZD was extracted from the OpenVigil FDA data platform for safety signal analysis. The combined risk ratio model, reporting ratio method, Ω shrinkage measure model, and chi-square statistics model were used to analyze the safety signals related to DDIs. Meanwhile, we evaluated the correlation and the influence of sex and age between the drug(s) and the target AE detected. There were 18991 AEs related to LZD. There were 2293, 1726, 4449, 821, 2431, 1053, and 463 AE reports when LZD was combined with amikacin, voriconazole, meropenem, clarithromycin, levofloxacin, piperacillin-tazobactam, and azithromycin, respectively. Except for azithromycin, there were positive safety signals related to DDIs between LZD and these antibiotics. These DDIs might influence the incidence of 13, 16, 7, 7, 6, and 15 types of AEs, respectively, and is associated with higher reporting rates of AEs compared with use alone. Moreover, sex and age might influence the occurrence of AEs. We found that the combinations of LZD and other antibiotics are related to multiple AEs, such as hepatotoxicity, drug resistance and electrocardiogram QT prolonged, but further research is still required to investigate their underlying mechanisms. This study can provide a new reference for the safety monitoring of LZD combined with other antibiotics in clinical practice.

Efficacies of omadacycline + amikacin + imipenem and an all-oral regimen omadacycline + clofazimine + linezolid in a mouse model of M. abscessus lung disease.

Treatment outcomes for Mycobacteroides abscessus (Mab, also known as Mycobacterium abscessus) disease are still unsatisfactory, mainly due to issues with drug toxicity, tolerability, and efficacy. Treating Mab disease is challenging due to its high baseline antibiotic resistance, initial requirement for intravenous therapy, and poor medication tolerance. Omadacycline, a new tetracycline, is active against Mab. Since any new antibiotic effective against Mab is expected to be used in combination with other antibiotics, we evaluated the efficacy of two triple-drug combinations comprising omadacycline, omadacycline + amikacin + imipenem, and omadacycline + clofazimine + linezolid against two contemporary Mab clinical isolates in a mouse model of Mab lung disease. Antibiotic administration was initiated 1-week post-infection and was given daily, with Mab burden in the lungs at treatment completion serving as the endpoint. Omadacycline alone moderately reduced Mab levels and maintained better health in mice compared to untreated ones, which typically suffered from the infection. The omadacycline + clofazimine + linezolid combination showed immediate bactericidal activity and enhanced efficacy over 6 weeks, particularly against the more resistant strain (M9507). However, the clofazimine + linezolid combination lacked early bactericidal activity. When combined with amikacin and imipenem, omadacycline did not improve the regimen's effectiveness over 4 weeks of treatment. Our study showed that omadacycline + clofazimine + linezolid exhibited significant bactericidal activity over an extended treatment duration. However, adding omadacycline to amikacin and imipenem did not improve regimen effectiveness against the evaluated clinical isolates within 4 weeks. Further research in Mab disease patients is needed to determine the most effective omadacycline-containing regimen.IMPORTANCEMycobacteroides abscessus is a common environmental bacterium that causes infections in people with compromised lung function, including those with bronchiectasis, cystic fibrosis, chronic obstructive pulmonary disease, and weakened immune systems, especially among older individuals. Treating M. abscessus disease is challenging due to the limited effectiveness and toxicity of current antibiotics, which often require prolonged use. Omadacycline, a new antibiotic, shows promise against M. abscessus. Using a mouse model that mimics M. abscessus disease in humans, we studied the effectiveness of including omadacycline with recommended antibiotics. Adding omadacycline to clofazimine and linezolid significantly improved treatment outcomes, rapidly clearing the bacteria from the lungs and maintaining effectiveness throughout. This oral combination is convenient for patients. However, adding omadacycline to amikacin and imipenem did not improve treatment effectiveness within 4 weeks. Further study with M. abscessus patients is necessary to optimize omadacycline-based treatment strategies for this disease.

Therapeutic Drug Monitoring of Linezolid in Drug-Resistant Tuberculosis Patients: Clinical Factors and Hematological Toxicities.

Purpose: Previous studies have indicated that the development of severe adverse events is associated with linezolid peak concentration (Cmax), but the factors affecting linezolid Cmax and evidences on therapeutic drug monitoring to anticipate toxicity in drug-resistant tuberculosis (DR-TB) patients have not been clarified clearly. This study aimed to explore the factors influencing linezolid Cmax and investigate the association between linezolid concentration and hematological toxicity. Patients and Methods: This study included patients with drug-resistant tuberculosis treated with linezolid from January 2022 to September 2023. We analyzed the factors affecting linezolid Cmax using chi-squared and binary logistic regression. The diagnostic utility of linezolid Cmax in predicting hematological toxicity was evaluated using receiver operating characteristic (ROC) analysis. Results: A total of 76 patients were enrolled in the study. 63.20% met the standard rates for linezolid Cmax. Age (P=0.036), weight (P=0.0016), and creatinine clearance (P=0.0223) significantly correlated with the Cmax. Hematological toxicity was observed in 46.05% (35/76) of patients, characterized by thrombocytopenia (31.58%, 24/76), anemia (6.58%, 5/76), and leukopenia (21.05%, 16/76). ROC curve analysis confirmed the predictive value of linezolid Cmax for thrombocytopenia with an area under curve of 0.728. Conclusion: Suboptimal linezolid Cmax was prevalent among patients with DR-TB, with age, weight, and renal function emerging as influential factors. Elevated linezolid Cmax increases the risk of thrombocytopenia. Meticulous monitoring of linezolid Cmax is imperative during anti-DR-TB therapy to tailor treatment and mitigate hematological toxicity.

New Oxazolidinones for Tuberculosis: Are Novel Treatments on the Horizon?

Multidrug-resistant tuberculosis (MDR-TB) is a global health concern. Standard treatment involves the use of linezolid, a repurposed oxazolidinone. It is associated with severe adverse effects, including myelosuppression and mitochondrial toxicity. As such, it is imperative to identify novel alternatives that are better tolerated but equally or more effective. Therefore, this review aims to identify and explore the novel alternative oxazolidinones to potentially replace linezolid in the management of TB. The keywords tuberculosis and oxazolidinones were searched in PubMed to identify eligible compounds. The individual drug compounds were then searched with the term tuberculosis to identify the relevant in vitro, in vivo and clinical studies. The search identified sutezolid, tedizolid, delpazolid, eperezolid, radezolid, contezolid, posizolid and TBI-223, in addition to linezolid. An additional search resulted in 32 preclinical and 21 clinical studies. All novel oxazolidinones except posizolid and eperezolid resulted in positive preclinical outcomes. Sutezolid and delpazolid completed early phase 2 clinical studies with better safety and equal or superior efficacy. Linezolid is expected to continue as the mainstay therapy, with renewed interest in drug monitoring. Sutezolid, tedizolid, delpazolid and TBI-223 displayed promising preliminary results. Further clinical studies would be required to assess the safety profiles and optimize the dosing regimens.