Phenotypic and Genotypic Drug Resistance of Mycobacterium tuberculosis Strains Isolated from HIV-Infected Patients from a Third-Level Public Hospital in Mexico.

BACKGROUND: Drug-resistant tuberculosis (TB) is associated with higher mortality rates in patients with human immunodeficiency virus (HIV). In Mexico, the number of deaths due to TB among the HIV-positive population has tripled in recent years. METHODS: Ninety-three Mycobacterium tuberculosis strains isolated from the same number of HIV-infected patients treated in a public hospital in Mexico City were studied to determine the drug resistance to first- and second-line anti-TB drugs and to identify the mutations associated with the resistance. RESULTS: Of the 93 patients, 82.7% were new TB cases, 86% were male, and 73% had extrapulmonary TB. Most patients (94%) with a CD4 T-lymphocyte count <350 cells/mm3 were associated with extrapulmonary TB (p <0.0001), whilst most patients (78%) with a CD4 T-lymphocyte count >350 cells/mm3 were associated with pulmonary TB (p = 0.0011). Eighty-two strains were pan-susceptible, four mono-resistant, four poly-resistant, two multidrug-resistant, and one was extensively drug-resistant. In the rifampicin-resistant strains, rpoB S531L was the mutation most frequently identified, whereas the inhA C15T and katG S315T1 mutations were present in isoniazid-resistant strains. The extensively drug-resistant strain also contained the mutation gyrA D94A. CONCLUSIONS: These data highlight the need to promptly diagnose the drug resistance of M. tuberculosis among all HIV-infected patients by systematically offering access to first- and second-line drug susceptibility testing and to tailor the treatment regimen based on the resistance patterns to reduce the number of deaths in HIV-infected patients.

Genetic Diversity of Mycobacterium tuberculosis Strains Isolated from HIV-Infected Patients in Mexico.

There has been very limited investigation regarding the genetic diversity of Mycobacterium tuberculosis (MTb) strains isolated from human immunodeficiency virus (HIV)-infected patients in Mexico. In this study, we isolated 93 MTb strains from pulmonary and extrapulmonary samples of HIV-infected patients treated in a public hospital in Mexico City to evaluate the genetic diversity using spoligotyping and mycobacterial interspersed repetitive unit-variable-number tandem-repeat (MIRU-VNTR) typing (based on 24 loci). The cohort comprised 80 male and 13 female individuals. There was a positive correlation between a high HIV viral load (>100,000 copies) and extrapulmonary tuberculosis (TB) (r = 0.306, p = 0.008). Lineage 4 was the most frequent lineage (79 strains). In this lineage, we found the H clade (n = 24), including the Haarlem, H3, and H1 families; the T clade (n = 22), including T1 and T2; the X clade (n = 15), including X1 and X3; the LAM clade (n = 14), including LAM1, LAM2, LAM3, LAM6, and LAM9; the S clade (n = 2); Uganda (n = 1); and Ghana (n = 1). We also found 12 strains in the EAI clade belonging to lineage 1, including the EAI2-Manila and EAI5 families. Interestingly, we identified one strain belonging to the Beijing family, which is part of lineage 2. One strain could not be identified. This study reports high genetic diversity among MTb strains, highlighting the need for a molecular epidemiological surveillance system that can help to monitor the spread of these strains, leading to more appropriate measures for TB control in HIV-infected patients.

A bioinformatics pipeline for Mycobacterium tuberculosis sequencing that cleans contaminant reads from sputum samples.

Next-Generation Sequencing (NGS) is widely used to investigate genomic variation. In several studies, the genetic variation of Mycobacterium tuberculosis has been analyzed in sputum samples without previous culture, using target enrichment methodologies for NGS. Alignments obtained by different programs generally map the sequences under default parameters, and from these results, it is assumed that only Mycobacterium reads will be obtained. However, variants of interest microorganism in clinical samples can be confused with a vast collection of reads from other bacteria, viruses, and human DNA. Currently, there are no standardized pipelines, and the cleaning success is never verified since there is a lack of rigorous controls to identify and remove reads from other sputum-microorganisms genetically similar to M. tuberculosis. Therefore, we designed a bioinformatic pipeline to process NGS data from sputum samples, including several filters and quality control points to identify and eliminate non-M. tuberculosis reads to obtain a reliable genetic variant report. Our proposal uses the SURPI software as a taxonomic classifier to filter input sequences and perform a mapping that provides the highest percentage of Mycobacterium reads, minimizing the reads from other microorganisms. We then use the filtered sequences to perform variant calling with the GATK software, ensuring the mapping quality, realignment, recalibration, hard-filtering, and post-filter to increase the reliability of the reported variants. Using default mapping parameters, we identified reads of contaminant bacteria, such as Streptococcus, Rhotia, Actinomyces, and Veillonella. Our final mapping strategy allowed a sequence identity of 97.8% between the input reads and the whole M. tuberculosis reference genome H37Rv using a genomic edit distance of three, thus removing 98.8% of the off-target sequences with a Mycobacterium reads loss of 1.7%. Finally, more than 200 unreliable genetic variants were removed during the variant calling, increasing the report's reliability.

COVID-19 and Tuberculosis Coinfection in a 51-Year-Old Taxi Driver in Mexico City.

BACKGROUND Coinfection with severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2) and Mycobacterium tuberculosis (MBT) has been reported, albeit rarely, in various parts of the world and has received attention from health systems because up to one-third of the world's population has been infected with SARS-CoV-2. Mexico was not included in the first-ever report on a global cohort of patients with this coinfection. We report on a case of SARS-CoV-2/MBT coinfection in a 51-year-old taxi driver from Mexico City that underscores the importance of rapid and accurate laboratory testing, diagnosis, and treatment. CASE REPORT We present the case of a man in the sixth decade of life who was admitted to the National Institute of Respiratory Diseases (INER) with a diagnosis of COVID-19 pneumonia, which was confirmed by nasopharyngeal exudate using real-time polymerase chain reaction (RT-PCR) for the identification of SARS-CoV-2. Findings from imaging studies suggested that the patient might be coinfected with MBT. That suspicion was confirmed with light microscopy of a sputum sample after Ziehl-Neelsen staining and when a Cepheid Xpert MTB/RIF assay, an automated semi-quantitative RT-PCR assay, failed to detect rifampicin resistance. The patient was discharged from the hospital 10 days later. CONCLUSIONS The present report underscores the importance of using validated molecular diagnostic tests to identify coinfections in areas where there is a high prevalence of other causes of pneumonia, such as MBT, as a way to improve clinical outcomes in patients during the COVID-19 pandemic. While it is imperative to control the COVID-19 pandemic, the medical community must not forget about the other pandemics to which populations are still prey, and tuberculosis is one of them. We must remain alert to any clinical subtleties so as to ensure timely and accurate diagnosis and stay one step ahead of COVID-19.