Incidence of tuberculosis in inflammatory rheumatic diseases: results from a Lithuanian retrospective cohort study

Background and objective: With an increase in survival rates among rheumatic patients, comorbidities and infections, in particular, have gained more importance, especially after the introduction of biologicals to the treatment algorithms. Tuberculosis (TB) infection has always been given a special attention in patients with rheumatic diseases (RD). Although Lithuanian population has one of the highest TB incidence rates among European countries, the incidence of TB in the rheumatic patients' population is still unknown. The aim of this study was to assess the incidence rate of TB in an inflammatory RD retrospective cohort and to compare that rate with a rate in a general population. Methods: Patients with the first-time diagnosis of inflammatory RD during the period between 1 January 2012 and 31 December 2017 were identified from the Lithuanian Compulsory Health Insurance Information System database SVEIDRA. All cases were cross-checked with Health Information center at the Institute of Hygiene, for the vital status of these patients and date of death if the fact of death was documented, and with Tuberculosis Register operated by Vilnius University Hospital Santaros Klinikos, for the confirmation of TB cases. Sex and age standardized incidence ratios (SIR) were calculated by dividing the observed numbers of TB among rheumatic patients by the expected number of cases, calculated using national rates from Lithuanian Department of Statistics Official Statistics website. Results: Overall, 8779 patients with newly diagnosed RD were identified during the 2013-2017 period, these included 458 patients who used biological disease modifying drugs (bDMARDs). The mean duration of the follow-up period was 2.71 years. The cohort consisted mainly of women (70%) and a half of the cohort were rheumatoid arthritis (RA) patients (53%). Mean age of patients at the time of RD diagnosis was 56 years (range = 18-97 years). There were 9 TB cases identified during 23,800 person years of follow-up: 2 cases among them were treated with bDMARDs. The mean calculated annual TB incidence in RD cohort was 37.81 per 100,000 person years, which is consistent with the incidence rate predicted by national estimates, with a resultant SIR of 0.90 (0.41-1.70). The unadjusted hazard ratio for bDMARD use versus no bDMARD use was 4.54 (0.94; 21.87) in a total cohort and very similar in rheumatoid arthritis cohort; in both cohorts, it was not a statistically significant risk. Conclusions: Here, we present the first nationwide cohort study to assess the incidence of TB in a broad spectrum of inflammatory RD. Although limited by short follow-up period, this study shows that TB incidence in RD cohort does not exceed TB incidence in the general Lithuanian population

Spoligotyping of Mycobacterium tuberculosis - Comparing in vitro and in silico approaches /

Spoligotyping is one of the molecular typing methods widely used for exploring the genetic variety of Mycobacterium tuberculosis. The aim of this study was to compare the spoligoprofiles of M. tuberculosis clinical isolates, obtained using in vitro and in silico approaches. The study included 230 M. tuberculosis isolates, recovered from Poland and Lithuania between 2018 and 2021. Spoligotyping in vitro was performed with a commercially available kit. Whole genome sequencing (WGS) was done with Illumina NovaSeq 6000 sequencer. Spoligotype International Types (SITs) were assigned according to the SITVIT2 database or using three different in silico tools, and based on WGS data, namely SpoTyping, SpolPred, and lorikeet. Upon in vitro spoligotyping, the isolates produced 65 different spoligotypes. Spoligotypes inferred from the WGS data were congruent with in vitro generated patterns in 81.7% (188/230) for lorikeet and 81.3% (187/230) for SpolPred and SpoTyping. Spacers 18 and 31 produced the highest ratio of discrepant results between in vitro and in silico approaches, with their signals discordantly assigned for 15 (6.5%) and 9 (3.9%) isolates, respectively. All three in silico approaches used were similarly efficient for M. tuberculosis spoligotype prediction. However, only SpoTyping could predict spoligotypes without a need for manual curation. Thus, we consider it as the most accurate tool. Its use is further advocated by the shortest time of analysis. A relatively high (ca. 20%) discordance between in vitro and in silico spoligotyping results was observed. While we discourage comparing conventional spoligotyping with in silico equivalents, we advise the use of the latter, as it improves the accuracy of spoligopatterns, and thus depicts the relatedness between the isolates more reliably