ABSTRACT
The treatment of drug-resistant Mycobacterium tuberculosis relies on complex antibiotic therapy. Inadequate antibiotic exposure can lead to treatment failure, acquired drug resistance, and an increased risk of adverse events. Therapeutic drug monitoring (TDM) can be used to optimize the antibiotic exposure. Therefore, we aimed to develop a single-run multiplex assay using high-performance liquid chromatography-mass spectrometry (HPLC-MS) for TDM of patients with multidrug-resistant, pre-extensively drug-resistant and extensively drug-resistant tuberculosis. A target profile for sufficient performance, based on the intended clinical application, was established and the assay was developed accordingly. Antibiotics were analyzed on a zwitterionic hydrophilic interaction liquid chromatography column and a triple quadrupole mass spectrometer using stable isotope-labeled internal standards. The assay was sufficiently sensitive to monitor drug concentrations over five half-lives for rifampicin, rifabutin, levofloxacin, moxifloxacin, bedaquiline, linezolid, clofazimine, terizidone/cycloserine, ethambutol, delamanid, pyrazinamide, meropenem, prothionamide, and para-amino salicylic acid (PAS). Accuracy and precision were sufficient to support clinical decision making (≤±15% in clinical samples and ±20-25% in spiked samples, with 80% of future measured concentrations predicted to fall within ±40% of nominal concentrations). The method was applied in the TDM of two patients with complex drug-resistant tuberculosis. All relevant antibiotics from their regimens could be quantified and high-dose therapy was initiated, followed by microbiological conversion. In conclusion, we developed a multiplex assay that enables TDM of the relevant first- and second-line anti-tuberculosis medicines in a single run and was able to show its applicability in TDM of two drug-resistant tuberculosis patients.
ABSTRACT
BACKGROUND: The incidence, geographical distribution and clinical relevance of different nontuberculous mycobacteria (NTM) in Croatia are well described. There are few data on the risk factors for developing NTM pulmonary disease (NTM-PD) in this setting. METHODS: We conducted a retrospective cohort study on all Croatian residents with NTM isolated from respiratory samples in the period from 2006 to 2015 with follow-up to 2018. The American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines were used to establish NTM-PD diagnosis. Clinical, radiological and treatment data were collected from hospital records. RESULTS: Risk analysis calculations were made on the 439 isolation episodes that were classified as definitive NTM-PD (nâ¯= 137) or no disease (nâ¯= 302). Female gender, presence of bronchiectasis, low BMI and long-term systemic corticosteroid treatment were independent risk factors associated with NTM-PD. Hemoptysis and malaise were presenting symptoms independently associated with NTM-PD. Chronic obstructive pulmonary disease (COPD) and low/moderate dose inhaled corticosteroid (ICS) treatment were not associated with NTM-PD. High dose ICS treatment was a significant risk factor for developing NTM-PD (aORâ¯= 4.73, CI 1.69-13.23 pâ¯= 0.003). CONCLUSION: The NTM-PD patients in Croatia are similar to those in other published cohorts in terms of their characteristics and risk factors. The significant dose-dependent association between ICS use and NTM-PD adds to the body of evidence suggesting that high dose ICS use is associated with NTM-PD.
