Analysis of Phenotypic and Genotypic Susceptibility to Clarithromycin and Amikacin of Mycobacterium abscessus Complex Strains Isolated from Cystic Fibrosis Patients

Mycobacterium; Amikacin; ClarithromycinMicobacteria; Amikacina; ClaritromicinaMicobacteri; Amikacina; ClaritromicinaMycobacterium abscessus complex infections are ever on the rise. To curb their increasing evolution, we performed an in-depth study of 43 clinical isolates of cystic fibrosis patients obtained from 2009 to 2020. We identified their subspecies, uncovered their genotypic resistance profiles, characterised their antibiotic-resistant genes, and assessed their phenotypic antibiotic susceptibilities. The phenotypic and genotypic methods showed total agreement in terms of resistance to clarithromycin and amikacin. Of the 43 clinical strains, 28 belonged to M. abscessus subsp. abscessus (65.1%), 13 to M. abscessus subsp. massiliense (30.2%), and 2 to M. abscessus subsp. bolletii (4.6%). The resistant rates for clarithromycin and amikacin, the two main drugs against M. abscessus complex pulmonary infections, were 64.2% and 14.2%, respectively. We found three strains of M. abscessus subsp. abscessus that showed heteroresistance in the rrl and rrs genes, and these strains also presented double-resistance since they were macrolide- and aminoglycoside-resistant. M. abscessus subsp. abscessus showed a high minimum inhibitory concentration (MIC) and a resistant percentage larger than or equal to 88% to cefoxitin, ciprofloxacin, moxifloxacin, doxycycline, imipenem, and trimethoprim-sulfamethoxazole. These results show a panorama of the high resistance of Mycobacterium abscessus complex to current drugs for cystic fibrosis patients. Thus, other treatment methods are urgently needed.This research received funding from the Fundació Hospital Universitari Vall Hebron—Institut de Recerca

Epidemiology and diagnosis of pleural tuberculosis in a low incidence country with high rate of immigrant population : A retrospective study

Background: The confirmatory diagnosis of pleural tuberculosis (pTB) remains challenging. The aim of this study was to describe the clinical and epidemiological characteristics of pTB patients and assess the yield of different diagnostic procedures in a low burden country with a high rate of immigrant population. Methods: All adult patients with pTB between 2007 and 2014 were studied retrospectively. Results: One hundred and three out of 843 patients with tuberculosis had pTB. Fifty-three (54.1%) were male, and the median age was 45 years (range 18-87 years). Fifty-two (50.49%) patients were immigrants. A confirmed diagnosis was reached in 16 patients (15.5%) by microbiological studies of pleural effusion. Lung involvement was demonstrated by sputum smear microscopy in 13/49 (26.5%), sputum GeneXpert MTB/RIF test in 13/20 (65%), and sputum culture in 16/37 (43.2%). High-resolution computed tomography (CT) showed lung involvement in 47.7% of the patients. The cure rate was 91.3% at the 1-year follow-up. Three patients died, all of them within the first month after diagnosis. Conclusions: The detection of lung involvement increased by two-fold when lung CT was used; this correlated with the likelihood of finding a positive microbiological result on sputum sample testing. Pleural microbiological studies had a low diagnostic yield, and sputum could have a complementary role

Immunogenicity of Mycobacterial Extracellular Vesicles Isolated From Host-Related Conditions Informs About Tuberculosis Disease Status

Tuberculosis (TB) still represents a major global health problem affecting over 10 million people worldwide. The gold-standard procedures for TB diagnosis are culture and nucleic acid amplification techniques. In this context, both lipoarabinomannan (LAM) urine test and rapid molecular tests have been major game changers. However, the low sensitivity of the former and the cost and the prohibitive infrastructure requirements to scale-up in endemic regions of the latter, make the improvement of the TB diagnostic landscape a priority. Most forms of life produce extracellular vesicles (EVs), including bacteria despite differences in bacterial cell envelope architecture. We demonstrated that Mycobacterium tuberculosis (Mtb), the causative agent of TB, produces EVs in vitro and in vivo as part of a sophisticated mechanism to manipulate host cellular physiology and to evade the host immune system. In a previous serology study, we showed that the recognition of several mycobacterial extracellular vesicles (MEV) associated proteins could have diagnostic properties. In this study, we pursued to expand the capabilities of MEVs in the context of TB diagnostics by analyzing the composition of MEVs isolated from Mtb cultures submitted to iron starvation and, testing their immunogenicity against a new cohort of serum samples derived from TB+ patients, latent TB-infected (LTBI) patients and healthy donors. We found that despite the stringent condition imposed by iron starvation, Mtb reduces the number of MEV associated proteins relative to iron sufficient conditions. In addition, TB serology revealed three new MEV antigens with specific biomarker capacity. These results suggest the feasibility of developing a point-of-care (POC) device based on selected MEV-associated proteins

Molecular characterization of rpoB gene mutations in isolates from tuberculosis patients in Cubal, Republic of Angola

Angola; Rifampicina; Mutaciones rpoBAngola; Rifampicina; Mutacions rpoBAngola; Rifampicin; rpoB mutationsBackground The importance of Mycobacterium tuberculosis strains with disputed rpoB mutations remains to be defined. This study aimed to assess the frequency and types of rpoB mutations in M. tuberculosis isolates from Cubal, Angola, a country with a high incidence of tuberculosis. Methods All isolates included (n = 308) were analyzed using phenotypic drug susceptibility testing and GenoType MTBDRplus assay. DNA sequencing of the rpoB gene and determination of rifampicin MIC by macrodilution method were additionally performed on isolates yielding discordant results (n = 12) and those in which the mutation detected was not characterized (n = 8). Results In total, 85.1% (74/87) of rifampicin-resistant strains had undisputed rpoB mutations -S450L (49), D435V (15), H445D (3), H445Y (2), Q432ins (1), L449M plus S450F (1), S450F (1), S450W (1) and S450Y (1)-; 10.3% (9/87) had disputed rpoB mutations—L430P plus S493L (1), N437del (1), H445L (3), D435Y (2), L452P (2)-, 2.3% (2.3%) showed no rpoB mutations and 2.3% (2/87) showed heteroresistance—D435Y plus L452P and L430P plus S493L-. Conclusion Disputed rpoB mutations were common, occurring in 10.3% of rifampicin resistant isolates. Current phenotyping techniques may be unable to detect this resistance pattern. To increase their sensitivity, a lower concentration of RIF could be used in these tests or alternatively, rpoB mutations could be screened and characterized in all M. tuberculosis strains.This work was supported by Probitas Foundation. Thanks to the financial support received from Probitas Foundation it was possible not only purchase the equipment and reagents to launch the study but to strengthen the capacity of the laboratory and local staff

Adherence and Toxicity during the Treatment of Latent Tuberculous Infection in a Referral Center in Spain

Latent tuberculosis infection; Toxicity; Tuberculosis screeningInfecció tuberculosa latent; Toxicitat; Cribratge de tuberculosiInfección tuberculosa latente; Toxicidad; Cribado de tuberculosisThe screening and treatment of latent tuberculosis infection (LTBI) in countries with a low incidence of TB is a key strategy for the elimination of tuberculosis (TB). However, treatment can result in adverse events (AEs) and have poor adherence. This study aimed to describe treatment outcomes and AEs for LTBI patients at two departments in Vall d'Hebron University Hospital in Barcelona, Spain. A retrospective study was conducted on all persons treated for LTBI between January 2018 and December 2020. Variables collected included demographics, the reason for LTBI screening and treatment initiation, AEs related to treatment, and treatment outcome. Out of 261 persons who initiated LTBI treatment, 145 (55.6%) were men, with a median age of 42.1 years. The indications for LTBI screening were household contact of a TB case in 96 (36.8%) persons, immunosuppressive treatment in 84 (32.2%), and recently arrived migrants from a country with high TB incidence in 81 (31.0%). Sixty-three (24.1%) persons presented at least one AE during treatment, and seven (2.7%) required definitive discontinuation of treatment. In the multivariate analysis, AE development was more frequent in those who started LTBI treatment due to immunosuppression. Overall, 226 (86.6%) completed treatment successfully. We concluded that LTBI screening and treatment groups had different risks for adverse events and treatment outcomes. Persons receiving immunosuppressive treatment were at higher risk of developing AEs, and recently arrived immigrants from countries with a high incidence of TB had greater LTFU. A person-centered adherence and AE management plan is recommended.A.M.L. was supported by a postdoctoral grant “Juan Rodés” (JE21/00027) from the Instituto de Salud Carlos through the Ministry of Economy and Competitiveness, Spain

Complete Genome Sequences of Four Mycobacteriophages Involved in Directed Evolution against Undisputed <i>Mycobacterium abscessus</i> Clinical Strains

Phage therapy is still in its infancy, but it is increasingly promising as a future alternative for treating antibiotic-resistant bacteria. To investigate the effect of phages on Mycobacterium abscessus complex (MABC), we isolated 113 environmental phages, grown them to high titres, and assayed them on MABC clinical strains through the spot test. Of all the phages, only 16 showed killing activity. Their activity was so temperate to MABC that they could not generate any plaque-forming units (PFUs). The Appelmans method of directed evolution was carried out to evolve these 16 phages into more lytic ones. After only 11 of 30 rounds of evolution, every single clinical strain in our collection, including those that were unsusceptible up to this point, could be lysed by at least one phage. The evolved phages were able to form PFUs on the clinical strains tested. Still, they are temperate at best and require further training. The genomes of one random parental phage and three random evolved phages from Round 13 were sequenced, revealing a diversity of clusters and genes of a variety of evolutionary origins, mostly of unknown function. These complete annotated genomes will be key for future molecular characterisations

Epidemiology and Diagnosis of Tuberculous Lymphadenitis in a Tuberculosis Low-Burden Country

The aim of this article is to describe epidemiological and clinical data of patients with tuberculous lymphadenitis (TL) and evaluate the yield of the diagnostic techniques employed. Retrospective observational study was performed at the Vall d'Hebron University Hospital, Barcelona, Spain. All adult patients with confirmed TL (microbiologically) or probable TL (suspected by clinical presentation, cyto/histopathological features, and clinical improvement after specific treatment) diagnosed from January 2001 to December 2013 were included. One hundred twenty-two patients were included: 78 (63.9%) patients with confirmed diagnosis and 44 (36.1%) patients with probable TL. Seventy (57.4%) patients were nonnative residents. From 83 fine-needle aspiration (FNA) specimens, 54.8% (40/73) showed granulomatous inflammation, 62.5% (40/64) had positive mycobacterial culture, and 73.3% (11/15) tested positive with Xpert MTB/RIF (Cepheid, Sunnyvale, CA). From 62 biopsy samples, 96.8% (60/62) showed granulomatous inflammation, 64.6% (31/48) had positive mycobacterial culture, and 46.1% (6/13) tested positive with Xpert MTB/RIF. TL has increasingly been diagnosed in our setting, mostly because of cases diagnosed in nonnative residents. FNA is an easy and safe technique for the diagnosis of suspected TL, and the yield regarding mycobacterial culture seems to be similar to the obtained with biopsy. The Xpert MTB/RIF test from FNA specimens may increase the accuracy of the TL diagnosis and provides quicker results