HIV viral suppression and risk of viral rebound in patients on antiretroviral therapy: a two- year retrospective cohort study in Northern Tanzania.

BACKGROUND: The world is moving towards the third target of the Joint United Nations Programme on HIV/AIDS to ensure most people receiving antiretroviral therapy (ART) are virologically suppressed. Little is known about viral suppression at an undetectable level and the risk of viral rebound phenomenon in sub-Saharan Africa which covers 67% of the global HIV burden.This study aimed to investigate the proportion of viral suppression at an undetectable level and the risk of viral rebound among people living with HIV receiving ART in northern Tanzania. METHODOLOGY: A hospital based-retrospective study recruited people living with HIV who were on ART for at least two years at Kibong'oto Infectious Disease Hospital and Mawenzi Regional Referral Hospital in Kilimanjaro Region, Tanzania. Participants' two-year plasma HIV were captured at months 6, 12, and 24 of ART. Undetectable viral load was defined by plasma HIV of viral load (VL) less than 20copies/ml and viral rebound (VR) was considered to anyone having VL of more than 50 copies/ml after having history of undetectable level of the VL less than 20copies/ml. A multivariable log-binomial generalized linear model was used to determine factors for undetectable VL and viral VR. RESULTS: Among 416 PLHIV recruited, 226 (54.3%) were female. The mean (standard deviation) age was 43.7 (13.3) years. The overall proportion of undetectable VL was 68% (95% CI: 63.3-72.3) and 40.0% had viral rebound (95% CI: 34.7-45.6). Participants who had at least 3 clinic visits were 1.3 times more likely to have undetectable VL compared to those who had 1 to 2 clinic visits in a year (p = 0.029). Similarly, participants with many clinical visits ( > = 3 visits) per year were less likely to have VR compared to those with fewer visits ( = 2 visits) [adjusted relative risk (aRR) = 0.64; 95% CI: 0.44-0.93]. CONCLUSION: Participants who had fewer clinic visits per year(ART refills) were less likely to achieve viral suppression and more likely to experience viral rebound. Enhanced health education and close follow-up of PLHIV on antiretroviral therapy are crucial to reinforce adherence and maintain an undetectable viral load.

Pharmacokinetic-Pharmacodynamic Determinants of Clinical Outcomes for Rifampin-Resistant Tuberculosis: A Multisite Prospective Cohort Study.

BACKGROUND: Rifampin-resistant and/or multidrug-resistant tuberculosis (RR/MDR-TB) treatment requires multiple drugs, and outcomes remain suboptimal. Some drugs are associated with improved outcome. It is unknown whether particular pharmacokinetic-pharmacodynamic relationships predict outcome. METHODS: Adults with pulmonary RR/MDR-TB in Tanzania, Bangladesh, and the Russian Federation receiving local regimens were enrolled from June 2016 to July 2018. Serum was collected after 2, 4, and 8 weeks for each drug's area under the concentration-time curve over 24 hours (AUC0-24). Quantitative susceptibility of the M. tuberculosis isolate was measured by minimum inhibitory concentrations (MICs). Individual drug AUC0-24/MIC targets were assessed by adjusted odds ratios (ORs) for favorable treatment outcome, and hazard ratios (HRs) for time to sputum culture conversion. K-means clustering algorithm separated the cohort of the most common multidrug regimen into 4 clusters by AUC0-24/MIC exposures. RESULTS: Among 290 patients, 62 (21%) experienced treatment failure, including 30 deaths. Moxifloxacin AUC0-24/MIC target of 58 was associated with favorable treatment outcome (OR, 3.75; 95% confidence interval, 1.21-11.56; P = .022); levofloxacin AUC0-24/MIC of 118.3, clofazimine AUC0-24/MIC of 50.5, and pyrazinamide AUC0-24 of 379 mg × h/L were associated with faster culture conversion (HR >1.0, P < .05). Other individual drug exposures were not predictive. Clustering by AUC0-24/MIC revealed that those with the lowest multidrug exposures had the slowest culture conversion. CONCLUSIONS: Amidst multidrug regimens for RR/MDR-TB, serum pharmacokinetics and M. tuberculosis MICs were variable, yet defined parameters to certain drugs-fluoroquinolones, pyrazinamide, clofazimine-were predictive and should be optimized to improve clinical outcome. CLINICAL TRIALS REGISTRATION: NCT03559582.

Global estimates and determinants of antituberculosis drug pharmacokinetics in children and adolescents: a systematic review and individual patient data meta-analysis.

BACKGROUND: Suboptimal exposure to antituberculosis (anti-TB) drugs has been associated with unfavourable treatment outcomes. We aimed to investigate estimates and determinants of first-line anti-TB drug pharmacokinetics in children and adolescents at a global level. METHODS: We systematically searched MEDLINE, Embase and Web of Science (1990-2021) for pharmacokinetic studies of first-line anti-TB drugs in children and adolescents. Individual patient data were obtained from authors of eligible studies. Summary estimates of total/extrapolated area under the plasma concentration-time curve from 0 to 24 h post-dose (AUC0-24) and peak plasma concentration (C max) were assessed with random-effects models, normalised with current World Health Organization-recommended paediatric doses. Determinants of AUC0-24 and C max were assessed with linear mixed-effects models. RESULTS: Of 55 eligible studies, individual patient data were available for 39 (71%), including 1628 participants from 12 countries. Geometric means of steady-state AUC0-24 were summarised for isoniazid (18.7 (95% CI 15.5-22.6) h·mg·L-1), rifampicin (34.4 (95% CI 29.4-40.3) h·mg·L-1), pyrazinamide (375.0 (95% CI 339.9-413.7) h·mg·L-1) and ethambutol (8.0 (95% CI 6.4-10.0) h·mg·L-1). Our multivariate models indicated that younger age (especially <2 years) and HIV-positive status were associated with lower AUC0-24 for all first-line anti-TB drugs, while severe malnutrition was associated with lower AUC0-24 for isoniazid and pyrazinamide. N-acetyltransferase 2 rapid acetylators had lower isoniazid AUC0-24 and slow acetylators had higher isoniazid AUC0-24 than intermediate acetylators. Determinants of C max were generally similar to those for AUC0-24. CONCLUSIONS: This study provides the most comprehensive estimates of plasma exposures to first-line anti-TB drugs in children and adolescents. Key determinants of drug exposures were identified. These may be relevant for population-specific dose adjustment or individualised therapeutic drug monitoring.

"Honestly, this problem has affected me a lot": a qualitative exploration of the lived experiences of people with chronic respiratory disease in Sudan and Tanzania.

BACKGROUND: Over 500 million people live with chronic respiratory diseases globally and approximately 4 million of these, mostly from the low- and middle-income countries including sub-Saharan Africa, die prematurely every year. Despite high CRD morbidity and mortality, only very few studies describe CRDs and little is known about the economic, social and psychological dimensions of living with CRDs in sub-Saharan Africa. We aimed to gain an in-depth understanding of the social, livelihood and psychological dimensions of living with CRD to inform management of CRDs in Sudan and Tanzania. METHOD: We conducted 12 in-depth interviews in 2019 with people with known or suspected CRD and 14 focus group discussions with community members in Gezira state, Sudan and Dodoma region, Tanzania, to share their understanding and experience with CRD. The data was analysed using thematic framework analysis. RESULTS: People with CRD in both contexts reported experiences under two broad themes: impact on economic wellbeing and impact on social and psychological wellbeing. Capacity to do hard physical work was significantly diminished, resulting in direct and indirect economic impacts for them and their families. Direct costs were incurred while seeking healthcare, including expenditures on transportation to health facility and procurement of diagnostic tests and treatments, whilst loss of working hours and jobs resulted in substantial indirect costs. Enacted and internalised stigma leading to withdrawal and social exclusion was described by participants and resulted partly from association of chronic cough with tuberculosis and HIV/AIDS. In Sudan, asthma was described as having negative impact on marital prospects for young women and non-disclosure related to stigma was a particular issue for young people. Impaired community participation and restrictions on social activity led to psychological stress for both people with CRD and their families. CONCLUSION: Chronic respiratory diseases have substantial social and economic impacts among people with CRD and their families in Sudan and Tanzania. Stigma is particularly strong and appears to be driven partly by association of chronic cough with infectiousness. Context-appropriate measures to address economic impacts and chronic cough stigma are urgently needed as part of interventions for chronic respiratory diseases in these sub-Saharan African contexts.

Impact of early diagnosis of impaired glucose regulation in tuberculosis: Comparison of clinical outcomes in people with tuberculosis in Tanzania.

OBJECTIVE: Diabetes mellitus (DM) has been known to compromise tuberculosis (TB) treatment outcomes. Association data are limited for early hyperglycaemia detection and TB treatment outcomes. Thus, we assessed treatment outcomes including time to sputum conversion and death in TB participants with or without hyperglycaemia. METHODS: A prospective cohort study recruited TB participants receiving anti-TB treatment at health facilities in Tanzania between October 2019 and September 2020. Hyperglycaemia was defined as having pre-existing DM or pre-treatment random blood glucose of ≥7.8 mmol/L, in combination categorised as impaired glucose regulation (IGR). Those with IGR were further screened for hyperglycaemia severity using glycated haemoglobin. In case of unknown status, participants were tested for HIV. Time to death was determined at 6 months of TB treatment. RESULTS: Of 1344 participants, 187 (13.9%) had IGR, of whom 44 (23.5%) were HIV co-infected. Overall treatment success was 1206 (89.7%), and was similar among participants with or without IGR (p > 0.05). Time to death for participants with and without IGR was 18 versus 28 days (p = 0.870), respectively. Age ≥ 40 years (p = 0.038), bacteriological positive (p = 0.039), HIV (p = 0.009), or recurrent TB (p = 0.017) predicted death or treatment success during TB treatment in adjusted multivariable models. CONCLUSION: IGR did not influence clinical outcomes in TB patients with or without IGR in a programme of early IGR diagnosis and integration TB, HIV and DM care. Early detection and co-management of multi-morbidities among people diagnosed with TB may reduce likelihood of poor treatment outcomes in a programmatic setting.

Therapeutic Drug Monitoring of Anti-infective Drugs: Implementation Strategies for 3 Different Scenarios.

BACKGROUND: Therapeutic drug monitoring (TDM) supports personalized treatment. For successful implementation, TDM must have a turnaround time suited to the clinical needs of patients and their health care settings. Here, the authors share their views of how a TDM strategy can be tailored to specific settings and patient groups. METHODS: The authors selected distinct scenarios for TDM: high-risk, complex, and/or critically ill patient population; outpatients; and settings with limited laboratory resources. In addition to the TDM scenario approach, they explored potential issues with the legal framework governing dose escalation. RESULTS: The most important issues identified in the different scenarios are that critically ill patients require rapid turnaround time, outpatients require an easy sampling procedure for the sample matrix and sample collection times, settings with limited laboratory resources necessitate setting-specific analytic techniques, and all scenarios warrant a legal framework to capture the use of escalated dosages, ideally with the use of trackable dosing software. CONCLUSIONS: To benefit patients, TDM strategies need to be tailored to the intended population. Strategies can be adapted for rapid turnaround time for critically ill patients, convenient sampling for outpatients, and feasibility for those in settings with limited laboratory resources.

Clinical-demographic markers for improving diabetes mellitus diagnosis in people with tuberculosis in Tanzania.

BACKGROUND: Tuberculosis (TB) control is threatened by an increasing prevalence of diabetes mellitus (DM), particularly in endemic countries. Screening for DM is not routinely implemented in Tanzania; therefore, we aimed to screen for DM at TB diagnosis using clinical-demographic markers. METHODS: Our cross-sectional study recruited TB patients who received anti-TB treatment between October 2019 and September 2020 at health care facilities in three regions from Tanzania. Patients were screened for DM using DM symptoms (polydipsia, polyphagia and polyuria) and random blood glucose (RBG) testing. Patients with a history of DM and those with no history of DM but an RBG ≥ 7.8 mmol/L had point-of-care glycated haemoglobin (HbA1c) testing, and were considered to have DM if HbA1c was ≥ 48 mmol/mol. RESULTS: Of 1344 TB patients, the mean age was 41.0 (± 17.0) years, and 64.7% were male. A total of 1011 (75.2%) had pulmonary TB, and 133 (10.4%) had at least one DM symptom. Overall, the prevalence of DM was 7.8%, of which 36 (2.8%) TB patients with no history of DM were newly diagnosed with DM by RBG testing. TB/DM patients were older than those with only TB (50.0 ± 14.0 years vs 40.0 ± 17.0 years, p < 0.001). Patients with RBG ≥ 7.8 mmol/L were more likely to have pulmonary TB (p = 0.003), age ≥ 35 years (p = 0.018), and have at least one DM symptom (p < 0.001). There was a substantial agreement (Kappa = 0.74) between the on-site glucometer and point-of-care HbA1c tests in detecting DM range of hyperglycemia. CONCLUSION: The implementation of clinical-demographic markers and blood glucose screening identified the overall prevalence of DM and those at risk of DM in TB patients. Clinical-demographic markers are independent predictors for DM range hyperglycemia and highlight the importance of further diagnostic testing and early co-management of TB and DM.

Mycobactericidal Effects of Different Regimens Measured by Molecular Bacterial Load Assay among People Treated for Multidrug-Resistant Tuberculosis in Tanzania.

Rifampin or multidrug-resistant tuberculosis (RR/MDR-TB) treatment has largely transitioned to regimens free of the injectable aminoglycoside component, despite the drug class' purported bactericidal activity early in treatment. We tested whether Mycobacterium tuberculosis killing rates measured by tuberculosis molecular bacterial load assay (TB-MBLA) in sputa correlate with composition of the RR/MDR-TB regimen. Serial sputa were collected from patients with RR/MDR- and drug-sensitive TB at days 0, 3, 7, and 14, and then monthly for 4 months of anti-TB treatment. TB-MBLA was used to quantify viable M. tuberculosis 16S rRNA in sputum for estimation of colony forming units per ml (eCFU/ml). M. tuberculosis killing rates were compared among regimens using nonlinear-mixed-effects modeling of repeated measures. Thirty-seven patients produced 296 serial sputa and received treatment as follows: 13 patients received an injectable bedaquiline-free reference regimen, 9 received an injectable bedaquiline-containing regimen, 8 received an all-oral bedaquiline-based regimen, and 7 patients were treated for drug-sensitive TB with conventional rifampin/isoniazid/pyrazinamide/ethambutol (RHZE). Compared to the adjusted M. tuberculosis killing of -0.17 (95% confidence interval [CI] -0.23 to -0.12) for the injectable bedaquiline-free reference regimen, the killing rates were -0.62 (95% CI -1.05 to -0.20) log10 eCFU/ml for the injectable bedaquiline-containing regimen (P = 0.019), -0.35 (95% CI -0.65 to -0.13) log10 eCFU/ml for the all-oral bedaquiline-based regimen (P = 0.054), and -0.29 (95% CI -0.78 to +0.22) log10 eCFU/ml for the RHZE regimen (P = 0.332). Thus, M. tuberculosis killing rates from sputa were higher among patients who received bedaquiline but were further improved with the addition of an injectable aminoglycoside.

A mobile microvolume UV/visible light spectrophotometer for the measurement of levofloxacin in saliva.

INTRODUCTION: Therapeutic drug monitoring (TDM) for personalized dosing of fluoroquinolones has been recommended to optimize efficacy and reduce acquired drug resistance in the treatment of MDR TB. Therefore, the aim of this study was to develop a simple, low-cost, robust assay for TDM using mobile UV/visible light (UV/VIS) spectrophotometry to quantify levofloxacin in human saliva at the point of care for TB endemic settings. METHODS: All experiments were performed on a mobile UV/VIS spectrophotometer. The levofloxacin concentration was quantified by using the amplitude of the second-order spectrum between 300 and 400 nm of seven calibrators. The concentration of spiked samples was calculated from the spectrum amplitude using linear regression. The method was validated for selectivity, specificity, linearity, accuracy and precision. Drugs frequently co-administered were tested for interference. RESULTS: The calibration curve was linear over a range of 2.5-50.0 mg/L for levofloxacin, with a correlation coefficient of 0.997. Calculated accuracy ranged from -5.2% to 2.4%. Overall precision ranged from 2.1% to 16.1%. Application of the Savitsky-Golay method reduced the effect of interferents on the quantitation of levofloxacin. Although rifampicin and pyrazinamide showed analytical interference at the lower limit of quantitation of levofloxacin concentrations, this interference had no implication on decisions regarding the levofloxacin dose. CONCLUSIONS: A simple UV/VIS spectrophotometric method to quantify levofloxacin in saliva using a mobile nanophotometer has been validated. This method can be evaluated in programmatic settings to identify patients with low levofloxacin drug exposure to trigger personalized dose adjustment.

Levofloxacin pharmacokinetics in saliva as measured by a mobile microvolume UV spectrophotometer among people treated for rifampicin-resistant TB in Tanzania.

BACKGROUND: Early detection and correction of low fluoroquinolone exposure may improve treatment of MDR-TB. OBJECTIVES: To explore a recently developed portable, battery-powered, UV spectrophotometer for measuring levofloxacin in saliva of people treated for MDR-TB. METHODS: Patients treated with levofloxacin as part of a regimen for MDR-TB in Northern Tanzania had serum and saliva collected concurrently at 1 and 4 h after 2 weeks of observed levofloxacin administration. Saliva levofloxacin concentrations were quantified in the field via spectrophotometry, while serum was analysed at a regional laboratory using HPLC. A Bayesian population pharmacokinetics model was used to estimate the area under the concentration-time curve (AUC0-24). Subtarget exposures of levofloxacin were defined by serum AUC0-24 <80 mg·h/L. The study was registered at Clinicaltrials.gov with clinical trial identifier NCT04124055. RESULTS: Among 45 patients, 11 (25.6%) were women and 16 (37.2%) were living with HIV. Median AUC0-24 in serum was 140 (IQR = 102.4-179.09) mg·h/L and median AUC0-24 in saliva was 97.10 (IQR = 74.80-121.10) mg·h/L. A positive linear correlation was observed with serum and saliva AUC0-24, and a receiver operating characteristic curve constructed to detect serum AUC0-24 below 80 mg·h/L demonstrated excellent prediction [AUC 0.80 (95% CI = 0.62-0.94)]. Utilizing a saliva AUC0-24 cut-off of 91.6 mg·h/L, the assay was 88.9% sensitive and 69.4% specific in detecting subtarget serum AUC0-24 values, including identifying eight of nine patients below target. CONCLUSIONS: Portable UV spectrophotometry as a point-of-care screen for subtarget levofloxacin exposure was feasible. Use for triage to other investigation or personalized dosing strategy should be tested in a randomized study.

TB or not TB? Definitive determination of species within the Mycobacterium tuberculosis complex in unprocessed sputum from adults with presumed multidrug-resistant tuberculosis.

OBJECTIVES: Differences among Mycobacterium tuberculosis complex (MTC) species may predict drug resistance or treatment success. Thus, we optimised and deployed the genotype MTBC assay (gMTBC) to identify MTC to the species level, and then performed comparative genotypic drug-susceptibility testing to anti-tuberculosis drugs from direct sputum of patients with presumed multidrug-resistant tuberculosis (MDR-TB) by the MTBDRplus/sl reference method. METHODS: Patients with positive Xpert® MTB/RIF (Xpert) results were consented to provide early-morning-sputum for testing by the gMTBC and the reference MTBDRplus/sl. Chi-square or Fisher's exact test compared proportions. Modified Poisson regression modelled detection of MTC by gMTBC. RESULTS: Among 73 patients, 53 (73%) were male and had a mean age of 43 (95% CI; 40-45) years. In total, 34 (47%), 36 (49%) and 38 (55%) had positive gMTBC, culture and MTBDR respectively. Forty patients (55%) had low quantity MTC by Xpert, including 31 (78%) with a negative culture. gMTBC was more likely to be positive in patients with chest cavity 4.18 (1.31-13.32, P = 0.016), high-quantity MTC by Xpert 3.03 (1.35-6.82, P = 0.007) and sputum smear positivity 1.93 (1.19-3.14, P = 0.008). The accuracy of gMTBC in detecting MTC was 95% (95% CI; 86-98; κ = 0.89) compared to MTBDRplus/sl. All M. tuberculosis/canettii identified by gMTB were susceptible to fluoroquinolone and aminoglycosides/capreomycin. CONCLUSIONS: The concordance between the gMTBC assay and MTBDRplus/sl in detecting MTC was high but lagged behind the yield of Xpert MTB/RIF. All M. tuberculosis/canettii were susceptible to fluoroquinolones, a core drug in MDR-TB treatment regimens.

Whole genome sequencing of Mycobacterium tuberculosis isolates and clinical outcomes of patients treated for multidrug-resistant tuberculosis in Tanzania.

BACKGROUND: Tuberculosis (TB), particularly multi- and or extensive drug resistant TB, is still a global medical emergency. Whole genome sequencing (WGS) is a current alternative to the WHO-approved probe-based methods for TB diagnosis and detection of drug resistance, genetic diversity and transmission dynamics of Mycobacterium tuberculosis complex (MTBC). This study compared WGS and clinical data in participants with TB. RESULTS: This cohort study performed WGS on 87 from MTBC DNA isolates, 57 (66%) and 30 (34%) patients with drug resistant and susceptible TB, respectively. Drug resistance was determined by Xpert® MTB/RIF assay and phenotypic culture-based drug-susceptibility-testing (DST). WGS and bioinformatics data that predict phenotypic resistance to anti-TB drugs were compared with participant's clinical outcomes. They were 47 female participants (54%) and the median age was 35 years (IQR): 29-44). Twenty (23%) and 26 (30%) of participants had TB/HIV co-infection BMI < 18 kg/m2 respectively. MDR-TB participants had MTBC with multiple mutant genes, compared to those with mono or polyresistant TB, and the majority belonged to lineage 3 Central Asian Strain (CAS). Also, MDR-TB was associated with delayed culture-conversion (median: IQR (83: 60-180 vs. 51:30-66) days). WGS had high concordance with both culture-based DST and Xpert® MTB/RIF assay in detecting drug resistance (kappa = 1.00). CONCLUSION: This study offers comparison of mutations detected by Xpert and WGS with phenotypic DST of M. tuberculosis isolates in Tanzania. The high concordance between the different methods and further insights provided by WGS such as PZA-DST, which is not routinely performed in most resource-limited-settings, provides an avenue for inclusion of WGS into diagnostic matrix of TB including drug-resistant TB.

Gridlock from diagnosis to treatment of multidrug resistant tuberculosis (MDR-TB) in Tanzania: patients' perspectives from a focus group discussion.

BACKGROUND: Molecular diagnostics have revolutionized the diagnosis of multidrug resistant tuberculosis (MDR-TB). Yet in Tanzania we found delay in diagnosis with more than 70% of MDR-TB patients having a history of several previous treatment courses for TB signaling prior opportunities for diagnosis. We aimed to explore patients' viewpoints and experiences with personal and socio-behavioral obstacles from MDR-TB diagnosis to treatment in an attempt to understand these prior findings. METHODS: The study was conducted in December 2016 with MDR-TB patients admitted at Kibong'oto Infectious Diseases Hospital. A qualitative approach deploying focus group discussions (FGDs) was used to gather information. Groups were sex aggregated to allow free interaction and to gauge gender specific issues in the social and behavioral contexts. The FGDs explored pathways and factors in the service delivery that may have contributed in the delay in accessing MDR-TB diagnostics and/or treatment. Collected data were coded, categorized and thematically interpreted. RESULTS: Forty MDR-TB patients participated in six FGDs. Challenges and barriers contributing to the delay in accessing MDR-TB diagnosis to treatment were as follows: 1) Participants had a different understanding of MDR-TB that led to seeking services outside the conventional health system; 2) Socio-economic adversity made health-seeking behavior difficult and often unproductive; 3) In the health system, challenges included inadequacy of MDR-TB diagnostic centers, lack of knowledge on behalf of health care providers to consider MDR-TB and order appropriate diagnostics; 4) The specimen referral system for early diagnosis of MDR-TB was inefficient. Non-adherence of TB patients to first-line anti-TB drugs prior to MDR-TB diagnosis, given the multitude of barriers discussed, was coupled with both intentional and unintentional non-adherence of health care providers to international standards of TB care. CONCLUSION: Patient-centered strategies bridging communities and the health system are urgently required for optimum MDR-TB control in Tanzania.

Underestimated pyrazinamide resistance may compromise outcomes of pyrazinamide containing regimens for treatment of drug susceptible and multi-drug-resistant tuberculosis in Tanzania.

BACKGROUND: Tuberculosis (TB) is the leading cause of death from an infectious disease and the roll-out of rapid molecular diagnostics for rifampin resistance has resulted in a steady rise in the number of patients with multidrug-resistant (MDR)-TB referred for treatment. Pyrazinamide is used in susceptible TB treatment for 6 months when used in combination with rifampin, isoniazid and ethambutol and is an important companion drug in novel MDR-TB trials. This study was undertaken to determine the prevalence of pyrazinamide resistance by either phenotypic or pncA testing among patients admitted to a referral hospital in Tanzania for drug-susceptible and MDR-TB treatment. METHODS: Surveillance sputa were sent among subjects beginning TB therapy at the national MDR-TB referral hospital during a 6 month period in 2013-2014. Mycobacterial cultures of pretreatment sputa were performed at the Kilimanjaro Clinical Research Institute (KCRI) in the BACTEC mycobacterial growth indicator tubes (MGIT) 960 system. Speciation of M. tuberculosis complex was confirmed by MTBc assay. Isolates were sub-cultured on to Lowenstein-Jensen (LJ) slants. Phenotypic resistance to pyrazinamide was performed in the MGIT system while a real-time PCR with High Resolution Melt (HRM) technique was used to determine mutation in the pncA gene from the same pure subculture. Sputa were then collected monthly to determine the time to culture negativity. Final treatment outcome was determined. RESULTS: Ninety-one M. tuberculosis isolates from individual patients were available for analysis of which 30 (32.9%) had MDR-TB, the mean (±SD) age was 33 ± 10 years, and the majority 23 (76.7%) were males. Of the 30 MDR-TB patients, 15(50%) had isolates with pyrazinamide resistance by conventional MGIT testing. This proportion expectedly exceeded the number with pyrazinamide resistance in the 61 patients without MDR-TB, 13 (21.3%) (p = 0.008). Six (20%) of MDR-TB patients had a poor outcome including treatment failure. Among patients with treatment failure, 5 (83%) had pyrazinamide resistance compared to only 10 (41.6%) with treatment success (p = 0.08). Two patients died, and both had isolates with pyrazinamide resistance. No other pretreatment characteristic was associated with treatment outcome. CONCLUSION: Pyrazinamide susceptibility appears to be important in clinical outcomes for MDR-TB patients, and susceptibility testing appears to be a critical adjunct to TB care. The high proportion of PZA resistance in non-MDR TB cases calls for further local investigation.

Gridlock from diagnosis to treatment of multidrug-resistant tuberculosis in Tanzania: low accessibility of molecular diagnostic services and lack of healthcare worker empowerment in 28 districts of 5 high burden TB regions with mixed methods evaluation.

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) outcomes are adversely impacted by delay in diagnosis and treatment. METHODS: Mixed qualitative and quantitative approaches were utilized to identify healthcare system related barriers to implementation of molecular diagnostics for MDR-TB. Randomly sampled districts from the 5 highest TB burden regions were enrolled during the 4th quarter of 2016. District TB & Leprosy Coordinators (DTLCs), and District AIDS Coordinators (DACs) were interviewed, along with staff from all laboratories within the selected districts where molecular diagnostics tests for MDR-TB were performed. Furthermore, the 2015 registers were audited for all drug-susceptible but retreatment TB cases and TB collaborative practices in HIV clinics, as these patients were in principal targeted for drug susceptibility testing by rapid molecular diagnostics. RESULTS: Twenty-eight TB districts from the 5 regions had 399 patients reviewed for retreatment with a drug-susceptible regimen. Only 160 (40%) had specimens collected for drug-susceptibility testing, and of those specimens only 120 (75%) had results communicated back to the clinic. MDR-TB was diagnosed in 16 (13.3%) of the 120 specimens but only 12 total patients were ultimately referred for treatment. Furthermore, among the HIV/AIDS clinics served in 2015, the median number of clients with TB diagnosis was 92 cases [IQR 32-157] yet only 2 people living with HIV were diagnosed with MDR-TB throughout the surveyed districts. Furthermore, the districts generated 53 front-line healthcare workers for interviews. DTLCs with intermediate or no knowledge on the clinical application of XpertMTB/RIF were 3 (11%), and 10 (39%), and DACs with intermediate or no knowledge were 0 (0%) and 2 (8%) respectively (p = 0.02). Additionally, 11 (100%) of the laboratories surveyed had only the 4-module XpertMTB/RIF equipment. The median time that XpertMTB/RIF was not functional in the 12 months prior to the investigation was 2 months (IQR 1-4). CONCLUSIONS: Underutilization of molecular diagnostics in high-risk groups was a function of a lack of front-line healthcare workforce empowerment and training, and a lack of equipment access, which likely contributed to the observed delay in MDR-TB diagnosis in Tanzania.

Ethionamide Pharmacokinetics/Pharmacodynamics-derived Dose, the Role of MICs in Clinical Outcome, and the Resistance Arrow of Time in Multidrug-resistant Tuberculosis.

Background: Ethionamide is used to treat multidrug-resistant tuberculosis (MDR-TB). The antimicrobial pharmacokinetics/pharmacodynamics, the contribution of ethionamide to the multidrug regimen, and events that lead to acquired drug resistance (ADR) are unclear. Methods: We performed a multidose hollow fiber system model of tuberculosis (HFS-TB) study to identify the 0-24 hour area under the concentration-time curve (AUC0-24) to minimum inhibitory concentration (MIC) ratios that achieved maximal kill and ADR suppression, defined as target exposures. Ethionamide-resistant isolates underwent whole-genome and targeted Sanger sequencing. We utilized Monte Carlo experiments (MCEs) to identify ethionamide doses that would achieve the target exposures in 10000 patients with pulmonary tuberculosis. We also identified predictors of time-to-sputum conversion in Tanzanian patients on ethionamide- and levofloxacin-based regimens using multivariate adaptive regression splines (MARS). Results: An AUC0-24/MIC >56.2 was identified as the target exposure in the HFS-TB. Early efflux pump induction to ethionamide monotherapy led to simultaneous ethambutol and isoniazid ADR, which abrogated microbial kill of an isoniazid-ethambutol-ethionamide regimen. Genome sequencing of isolates that arose during ethionamide monotherapy revealed mutations in both ethA and embA. In MCEs, 20 mg/kg/day achieved the AUC0-24/MIC >56.2 in >95% of patients, provided the Sensititre assay MIC was <2.5 mg/L. In the clinic, MARS revealed that ethionamide Sensititre MIC had linear negative relationships with time-to-sputum conversion until an MIC of 2.5 mg/L, above which patients with MDR-TB failed combination therapy. Conclusions: Ethionamide is an important contributor to MDR-TB treatment regimens, at Sensititre MIC <2.5 mg/L. Suboptimal ethionamide exposures led to efflux pump-mediated ADR.

Levofloxacin Pharmacokinetics/Pharmacodynamics, Dosing, Susceptibility Breakpoints, and Artificial Intelligence in the Treatment of Multidrug-resistant Tuberculosis.

Background: Levofloxacin is used for the treatment of multidrug-resistant tuberculosis; however the optimal dose is unknown. Methods: We used the hollow fiber system model of tuberculosis (HFS-TB) to identify 0-24 hour area under the concentration-time curve (AUC0-24) to minimum inhibitory concentration (MIC) ratios associated with maximal microbial kill and suppression of acquired drug resistance (ADR) of Mycobacterium tuberculosis (Mtb). Levofloxacin-resistant isolates underwent whole-genome sequencing. Ten thousands patient Monte Carlo experiments (MCEs) were used to identify doses best able to achieve the HFS-TB-derived target exposures in cavitary tuberculosis and tuberculous meningitis. Next, we used an ensemble of artificial intelligence (AI) algorithms to identify the most important predictors of sputum conversion, ADR, and death in Tanzanian patients with pulmonary multidrug-resistant tuberculosis treated with a levofloxacin-containing regimen. We also performed probit regression to identify optimal levofloxacin doses in Vietnamese tuberculous meningitis patients. Results: In the HFS-TB, the AUC0-24/MIC associated with maximal Mtb kill was 146, while that associated with suppression of resistance was 360. The most common gyrA mutations in resistant Mtb were Asp94Gly, Asp94Asn, and Asp94Tyr. The minimum dose to achieve target exposures in MCEs was 1500 mg/day. AI algorithms identified an AUC0-24/MIC of 160 as predictive of microbiologic cure, followed by levofloxacin 2-hour peak concentration and body weight. Probit regression identified an optimal dose of 25 mg/kg as associated with >90% favorable response in adults with pulmonary tuberculosis. Conclusions: The levofloxacin dose of 25 mg/kg or 1500 mg/day was adequate for replacement of high-dose moxifloxacin in treatment of multidrug-resistant tuberculosis.

d-Cycloserine Pharmacokinetics/Pharmacodynamics, Susceptibility, and Dosing Implications in Multidrug-resistant Tuberculosis: A Faustian Deal.

Background: d-cycloserine is used to treat multidrug-resistant tuberculosis. Its efficacy, contribution in combination therapy, and best clinical dose are unclear, also data on the d-cycloserine minimum inhibitory concentration (MIC) distributions is scant. Methods: We performed a systematic search to identify pharmacokinetic and pharmacodynamic studies performed with d-cycloserine. We then performed a combined exposure-effect and dose fractionation study of d-cycloserine in the hollow fiber system model of tuberculosis (HFS-TB). In parallel, we identified d-cycloserine MICs in 415 clinical Mycobacterium tuberculosis (Mtb) isolates from patients. We utilized these results, including intracavitary concentrations, to identify the clinical dose that would be able to achieve or exceed target exposures in 10000 patients using Monte Carlo experiments (MCEs). Results: There were no published d-cycloserine pharmacokinetics/pharmacodynamics studies identified. Therefore, we performed new HFS-TB experiments. Cyloserine killed 6.3 log10 colony-forming units (CFU)/mL extracellular bacilli over 28 days. Efficacy was driven by the percentage of time concentration persisted above MIC (%TMIC), with 1.0 log10 CFU/mL kill achieved by %TMIC = 30% (target exposure). The tentative epidemiological cutoff value with the Sensititre MYCOTB assay was 64 mg/L. In MCEs, 750 mg twice daily achieved target exposure in lung cavities of 92% of patients whereas 500 mg twice daily achieved target exposure in 85% of patients with meningitis. The proposed MCE-derived clinical susceptibility breakpoint at the proposed doses was 64 mg/L. Conclusions: Cycloserine is cidal against Mtb. The susceptibility breakpoint is 64 mg/L. However, the doses likely to achieve the cidality in patients are high, and could be neurotoxic.

Population Pharmacokinetic Model and Limited Sampling Strategies for Personalized Dosing of Levofloxacin in Tuberculosis Patients.

Levofloxacin is an antituberculosis drug with substantial interindividual pharmacokinetic variability; therapeutic drug monitoring (TDM) could therefore be helpful to improve treatment results. TDM would be more feasible with limited sampling strategies (LSSs), a method to estimate the area under the concentration curve for the 24-h dosing interval (AUC0-24) by using a limited number of samples. This study aimed to develop a population pharmacokinetic (popPK) model of levofloxacin in tuberculosis patients, along with LSSs using a Bayesian and multiple linear regression approach. The popPK model and Bayesian LSS were developed using data from 30 patients and externally validated with 20 patients. The LSS based on multiple linear regression was internally validated using jackknife analysis. Only clinically suitable LSSs (maximum time span, 8 h; minimum interval, 1 h; 1 to 3 samples) were tested. Performance criteria were root-mean-square error (RMSE) of <15%, mean prediction error (MPE) of <5%, and r2 value of >0.95. A one-compartment model with lag time best described the data while only slightly underestimating the AUC0-24 (mean, -7.9%; standard error [SE], 1.7%). The Bayesian LSS using 0- and 5-h postdose samples (RMSE, 8.8%; MPE, 0.42%; r2 = 0.957) adequately estimated the AUC0-24, with a mean underestimation of -4.4% (SE, 2.7%). The multiple linear regression LSS using 0- and 4-h postdose samples (RMSE, 7.0%; MPE, 5.5%; r2 = 0.977) was internally validated, with a mean underestimation of -0.46% (SE, 2.0%). In this study, we successfully developed a popPK model and two LSSs that could be implemented in clinical practice to assist TDM of levofloxacin. (This study has been registered at ClinicalTrials.gov under identifier NCT01918397.).