Time-to-positivity of Mycobacterium avium complex in broth culture associates with culture conversion

Abstract

Background Mycobacterial time to positivity (TTP) in liquid culture media has predictive value for longer term outcomes in pulmonary tuberculosis, but has not been thoroughly studied in nontuberculous mycobacterial pulmonary disease. This study sought to evaluate for association between TTP and sputum culture conversion to negative in pulmonary disease caused by Mycobacterium avium complex (MAC). Methods Data from the CONVERT trial (NCT02344004) that evaluated efficacy of guideline-based-therapy with or without amikacin liposome inhalation suspension in adults with refractory MAC-PD (Mycobacterium avium complex pulmonary disease) were analyzed. We evaluated TTP measures for sputum obtained prior to study treatment initiation and at monthly visits, assessing reproducibility of measures as well as association of TTP with culture conversion on treatment. Results Data from 71 participants with at least one screening visit TTP value were analyzed. For participants who provided more than one sputum sample at a given visit, there was moderate between-sample reliability, with median intraclass correlation coefficient 0.62 (IQR 0.50, 0.70). Median TTP at screening was longer in those participants who subsequently achieved vs. did not achieve culture conversion (10.5 [IQR 9.4] days vs. 4.2 [IQR 2.8] days, p = 0.0002). Individuals with culture conversion by study treatment month 6 were more likely to have a screening TTP > 5 days compared to those who did not achieve culture conversion (OR 15.4, 95% CI 1.9, 716.7, p = 0.0037) and had increasing TTPs over time. Conclusions TTP prior to and on treatment is associated with microbiological treatment response in patients with MAC-PD.

Diagnostic efficiency of metagenomic next-generation sequencing for suspected spinal tuberculosis in China: A multicenter prospective study

“…Meanwhile, the administration of antimicrobial drugs before culture reduces organism recovery rates. In addition, bacterial culture is a time-consuming method, i.e., the general bacterial culture takes a few days, and TB bacterial culture takes 2 months ( Stangenberg et al, 2021 ; Mingora et al, 2022 ). Conventional PCR-based tests are targeted methods, and thus cannot be used effectively without some prior knowledge regarding the identity of the pathogen in question.…”

Incorporating direct molecular diagnostics in management algorithms for nontuberculous mycobacteria: Is it high time?

“…This strategy, when applied in conjunction with the appropriate clinical context, should limit over-treatment. Thirdly, unlike culture, direct molecular testing of sputum, cannot predict sputum culture conversion to negative and does not allow for quantitative culture evaluations that can assist in assessing the severity of the disease, monitor the course of treatment, and differentiate chromogenic from nonchromogenic mycobacteria that is not possible with direct molecular testing [41] , [42] , [43] . Lastly, due to the variable treatment response of NTM pulmonary disease, it is possible that achieving an earlier diagnosis may not guarantee a favorable treatment response.…”

Risk factors for microbiological persistence after 6 months of treatment for Mycobacterium intracellulare and its impact on the drug-resistance profile

“…The clinical practice guidelines of the American Thoracic Society (ATS), European Respiratory Society (ERS), European Society of Clinical Microbiology and Infectious Diseases (ESCMID), and Infectious Disease Society of America (IDSA) recommend the administration of antibiotics for a minimum of 12 months after negative culture conversion ( 10 ). Recent studies found that the factors related to culture conversion in patients with MAC pulmonary disease are radiological type, old age, and time to culture positivity at baseline ( 11 – 13 ). The Clinical and Laboratory Standards Institute (CLSI) guidelines recommend drug susceptibility testing (DST) for macrolides and amikacin to guide the design of the treatment regimen and optimize the treatment response ( 14 – 16 ).…”