SARS-CoV-2 intra-host diversity, antibody response, and disease severity after reinfection by the variant of concern Gamma in Brazil.

The rapid spread of the SARS-CoV-2 Variant of Concern (VOC) Gamma in Amazonas during early 2021 fueled a second large COVID-19 epidemic wave and raised concern about the potential role of reinfections. Very few cases of reinfection associated with the VOC Gamma have been reported to date, and their potential impact on clinical, immunological, and virological parameters remains largely unexplored. Here we describe 25 cases of SARS-CoV-2 reinfection in Brazil. SARS-CoV-2 genomic analysis confirmed that individuals were primo-infected with distinct viral lineages between March and December 2020 (B.1.1, B.1.1.28, B.1.1.33, B.1.195, and P.2) and reinfected with the VOC Gamma between 3 to 12 months after primo-infection. We found a similar mean cycle threshold (Ct) value and limited intra-host viral diversity in both primo-infection and reinfection samples. Sera of 14 patients tested 10-75 days after reinfection displayed detectable neutralizing antibodies (NAb) titers against SARS-CoV-2 variants that circulated before (B.1.*), during (Gamma), and after (Delta and Omicron) the second epidemic wave in Brazil. All individuals had milder or no symptoms after reinfection, and none required hospitalization. These findings demonstrate that individuals reinfected with the VOC Gamma may display relatively high RNA viral loads at the upper respiratory tract after reinfection, thus contributing to onward viral transmissions. Despite this, our study points to a low overall risk of severe Gamma reinfections, supporting that the abrupt increase in hospital admissions and deaths observed in Amazonas and other Brazilian states during the Gamma wave was mostly driven by primary infections. Our findings also indicate that most individuals analyzed developed a high anti-SARS-CoV-2 NAb response after reinfection that may provide some protection against reinfection or disease by different SARS-CoV-2 variants.

Genomic Surveillance of SARS-CoV-2 in Healthcare Workers: A Critical Sentinel Group for Monitoring the SARS-CoV-2 Variant Shift.

SARS-CoV-2 genome surveillance is important for monitoring risk groups and health workers as well as data on new cases and mortality rate due to COVID-19. We characterized the circulation of SARS-CoV-2 variants from May 2021 to April 2022 in the state of Santa Catarina, southern Brazil, and evaluated the similarity between variants present in the population and healthcare workers (HCW). A total of 5291 sequenced genomes demonstrated the circulation of 55 strains and four variants of concern (Alpha, Delta, Gamma and Omicron-sublineages BA.1 and BA.2). The number of cases was relatively low in May 2021, but the number of deaths was higher with the Gamma variant. There was a significant increase in both numbers between December 2021 and February 2022, peaking in mid-January 2022, when the Omicron variant dominated. After May 2021, two distinct variant groups (Delta and Omicron) were observed, equally distributed among the five Santa Catarina mesoregions. Moreover, from November 2021 to February 2022, similar variant profiles between HCW and the general population were observed, and a quicker shift from Delta to Omicron in HCW than in the general population. This demonstrates the importance of HCW as a sentinel group for monitoring disease trends in the general population.

Emergence of Two Distinct SARS-CoV-2 Gamma Variants and the Rapid Spread of P.1-like-II SARS-CoV-2 during the Second Wave of COVID-19 in Santa Catarina, Southern Brazil.

The western mesoregion of the state of Santa Catarina (SC), Southern Brazil, was heavily affected as a whole by the COVID-19 pandemic in early 2021. This study aimed to evaluate the dynamics of the SARS-CoV-2 virus spreading patterns in the SC state from March 2020 to April 2021 using genomic surveillance. During this period, there were 23 distinct variants, including Beta and Gamma, among which the Gamma and related lineages were predominant in the second pandemic wave within SC. A regionalization of P.1-like-II in the Western SC region was observed, concomitant to the increase in cases, mortality, and the case fatality rate (CFR) index. This is the first evidence of the regionalization of the SARS-CoV-2 transmission in SC and it highlights the importance of tracking the variants, dispersion, and impact of SARS-CoV-2 on the public health systems.

Unusual SARS-CoV-2 intrahost diversity reveals lineage superinfection.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has infected almost 200 million people worldwide by July 2021 and the pandemic has been characterized by infection waves of viral lineages showing distinct fitness profiles. The simultaneous infection of a single individual by two distinct SARS-CoV-2 lineages may impact COVID-19 disease progression and provides a window of opportunity for viral recombination and the emergence of new lineages with differential phenotype. Several hundred SARS-CoV-2 lineages are currently well phylogenetically defined, but two main factors have precluded major coinfection/codetection and recombination analysis thus far: (i) the low diversity of SARS-CoV-2 lineages during the first year of the pandemic, which limited the identification of lineage defining mutations necessary to distinguish coinfecting/recombining viral lineages; and the (ii) limited availability of raw sequencing data where abundance and distribution of intrasample/intrahost variability can be accessed. Here, we assembled a large sequencing dataset from Brazilian samples covering a period of 18 May 2020 to 30 April 2021 and probed it for unexpected patterns of high intrasample/intrahost variability. This approach enabled us to detect nine cases of SARS-CoV-2 coinfection with well characterized lineage-defining mutations, representing 0.61 % of all samples investigated. In addition, we matched these SARS-CoV-2 coinfections with spatio-temporal epidemiological data confirming its plausibility with the cocirculating lineages at the timeframe investigated. Our data suggests that coinfection with distinct SARS-CoV-2 lineages is a rare phenomenon, although it is certainly a lower bound estimate considering the difficulty to detect coinfections with very similar SARS-CoV-2 lineages and the low number of samples sequenced from the total number of infections.

Genomic characterization of variants on mycolic acid metabolism genes in Mycobacterium tuberculosis isolates from Santa Catarina, Southern Brazil.

Mycobacterium tuberculosis has a complex cell wall containing mycolic acids (MA), which play an important role in pathogenesis, virulence, and survival by protecting the cell against harsh environments. Studies have shown that genes encoding enzymes involved in MA synthesis are essential to mycobacterial functionality. Here, we used whole-genome sequencing to evaluate mutations in genes related to MA metabolism in M. tuberculosis isolates from pulmonary tuberculosis patients of the Florianópolis Metropolitan Area, Santa Catarina, Brazil, and assessed associations with clinical, epidemiological, and genotypic data. The mutations Rv3057c Asp112Ala (104/151), Rv3720 His70Arg (104/151), and Rv3802c Val50Phe (105/151) were identified in about 69% of the isolates and were related to the LAM lineage. SIT 216/LAM5 (13.2%, 20/151) had the highest frequency and presented the mutations accD2 Lys23Glu, kasA Gly269Ser, mmaA4 Asn165Ser, otsB1 Asp617Asn, Rv3057c Asp112Ala, Rv3720 His70Arg, Rv3802c Val50Phe, and tgs4 Ala216Glu. All SIT 73/T isolates (6.6%, 10/151) showed a characteristic and exclusive gene mutation pattern: amiD Rv3376 3790075G > A, fbpA-aftB 4266941G > A, echA11 Asn220fs, and otsB2 Ser110Arg. SITs 20/LAM1, 64/LAM6, 50/H3, 137/X2, and 119/X1 were also related to specific mutations. SITs from the LAM lineage differed in mutation profile from those of the T, Haarlem, and X lineages. Isolates from patients who had treatment failure showed mutations that do not seem to have a pattern related to this outcome. It was possible to identify a broad repertoire of single-nucleotide polymorphisms in genes related to MA metabolism in M. tuberculosis isolates. This study also described, for the first time, the variability between different SITs/sublineages of Lineage 4 circulating in Florianópolis Metropolitan Area.

The ongoing evolution of variants of concern and interest of SARS-CoV-2 in Brazil revealed by convergent indels in the amino (N)-terminal domain of the spike protein.

Mutations at both the receptor-binding domain (RBD) and the amino (N)-terminal domain (NTD) of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike (S) glycoprotein can alter its antigenicity and promote immune escape. We identified that SARS-CoV-2 lineages circulating in Brazil with mutations of concern in the RBD independently acquired convergent deletions and insertions in the NTD of the S protein, which altered the NTD antigenic-supersite and other predicted epitopes at this region. Importantly, we detected the community transmission of different P.1 lineages bearing NTD indels ∆69-70 (which can impact several SARS-CoV-2 diagnostic protocols), ∆144 and ins214ANRN, and a new VOI N.10 derived from the B.1.1.33 lineage carrying three NTD deletions (∆141-144, ∆211, and ∆256-258). These findings support that the ongoing widespread transmission of SARS-CoV-2 in Brazil generates new viral lineages that might be more resistant to antibody neutralization than parental variants of concern.

Identification of a novel SARS-CoV-2 P.1 sub-lineage in Brazil provides new insights about the mechanisms of emergence of variants of concern.

One of the most remarkable severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC) features is the significant number of mutations they acquired. However, the specific factors that drove the emergence of such variants since the second half of 2020 are not fully resolved. In this study, we describe a new SARS-CoV-2 P.1 sub-lineage circulating in Brazil, denoted here as Gamma-like-II, that as well as the previously described lineage Gamma-like-I shares several lineage-defining mutations with the VOC Gamma. Reconstructions of ancestor sequences support that most lineage-defining mutations of the Spike (S) protein, including those at the receptor-binding domain (RBD), accumulated at the first P.1 ancestor. In contrast, mutations outside the S protein were mostly fixed at subsequent steps. Our evolutionary analyses estimate that P.1-ancestral strains carrying RBD mutations of concern probably circulated cryptically in the Amazonas for several months before the emergence of the VOC Gamma. Unlike the VOC Gamma, the other P.1 sub-lineages displayed a much more restricted dissemination and accounted for a low fraction (<2 per cent) of SARS-CoV-2 infections in Brazil in 2021. The stepwise diversification of lineage P.1 through multiple inter-host transmissions is consistent with the hypothesis that partial immunity acquired from natural SARS-CoV-2 infections in heavily affected regions might have been a major driving force behind the natural selection of some VOCs. The lag time between the emergence of the P.1 ancestor and the expansion of the VOC Gamma and the divergent epidemic trajectories of P.1 sub-lineages support a complex interplay between the emergence of mutations of concern and viral spread in Brazil.

Author Correction: Genomic epidemiology of Mycobacterium tuberculosis in Santa Catarina, Southern Brazil.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Genomic epidemiology of Mycobacterium tuberculosis in Santa Catarina, Southern Brazil.

Mycobacterium tuberculosis (M.tb), the pathogen responsible for tuberculosis (TB) poses as the major cause of death among infectious diseases. The knowledge about the molecular diversity of M.tb enables the implementation of more effective surveillance and control measures and, nowadays, Whole Genome Sequencing (WGS) holds the potential to produce high-resolution epidemiological data in a high-throughput manner. Florianópolis, the state capital of Santa Catarina (SC) in south Brazil, shows a high TB incidence (46.0/100,000). Here we carried out a WGS-based evaluation of the M.tb strain diversity, drug-resistance and ongoing transmission in the capital metropolitan region. Resistance to isoniazid, rifampicin, streptomycin was identified respectively in 4.0% (n = 6), 2.0% (n = 3) and 1.3% (n = 2) of the 151 studied strains by WGS. Besides, resistance to pyrazinamide and ethambutol was detected in 0.7% (n = 1) and reistance to ethionamide and fluoroquinolone (FQ) in 1.3% (n = 2), while a single (0.7%) multidrug-resistant (MDR) strain was identified. SNP-based typing classified all isolates into M.tb Lineage 4, with high proportion of sublineages LAM (60.3%), T (16.4%) and Haarlem (7.9%). The average core-genome distance between isolates was 420.3 SNPs, with 43.7% of all isolates grouped across 22 genomic clusters thereby showing the presence of important ongoing TB transmission events. Most clusters were geographically distributed across the study setting which highlights the need for an urgent interruption of these large transmission chains. The data conveyed by this study shows the presence of important and uncontrolled TB transmission in the metropolitan area and provides precise data to support TB control measures in this region.

An evolutionary recent IFN/IL-6/CEBP axis is linked to monocyte expansion and tuberculosis severity in humans.

Monocyte counts are increased during human tuberculosis (TB) but it has not been determined whether Mycobacterium tuberculosis (Mtb) directly regulates myeloid commitment. We demonstrated that exposure to Mtb directs primary human CD34+ cells to differentiate into monocytes/macrophages. In vitro myeloid conversion did not require type I or type II IFN signaling. In contrast, Mtb enhanced IL-6 responses by CD34+ cell cultures and IL-6R neutralization inhibited myeloid differentiation and decreased mycobacterial growth in vitro. Integrated systems biology analysis of transcriptomic, proteomic and genomic data of large data sets of healthy controls and TB patients established the existence of a myeloid IL-6/IL6R/CEBP gene module associated with disease severity. Furthermore, genetic and functional analysis revealed the IL6/IL6R/CEBP gene module has undergone recent evolutionary selection, including Neanderthal introgression and human pathogen adaptation, connected to systemic monocyte counts. These results suggest Mtb co-opts an evolutionary recent IFN-IL6-CEBP feed-forward loop, increasing myeloid differentiation linked to severe TB in humans.

Molecular epidemiology of Mycobacterium tuberculosis strains from prison populations in Santa Catarina, Southern Brazil.

The Tuberculosis (TB) notification rates are 5 to 81 times higher in prisons worldwide when compared to the general population. The state of Santa Catarina (SC) has few epidemiological data regarding TB in prisons. The aim of this study was to evaluate the molecular epidemiology of circulating strains in prisons of SC. The study comprised 95 clinical samples from six prisons. Among the cases included, all subjects were male, predominantly caucasians, and young adults, with low education level. The positive smear in the TB diagnosis comprised 62.0% of cases. About 50% of subjects had some condition associated with TB. The Spoligotyping results showed that the most frequent lineages were LAM (50.7%), T (22.2%) and S (11.6%). The 12-loci MIRU generated 62 different genotypes. The MSTs showed evolutionary relationships between Mycobacterium tuberculosis spoligotypes from SC and evolutionary relationships between the prison isolates and studied parameters. This first study on TB in prison units of SC highlighted the predominance of SIT216/LAM5, and SIT34/S. Interestingly, his profile was found to be different from that observed in a previous study performed with the state's general population. This data shows the need for continued surveillance of episodes of TB occurring among prison inmates in an emerging country like Brazil.

Isoniazid-induced control of Mycobacterium tuberculosis by primary human cells requires interleukin-1 receptor and tumor necrosis factor.

Proinflammatory cytokines are critical mediators that control Mycobacterium tuberculosis (Mtb) growth during active tuberculosis (ATB). To further inhibit bacterial proliferation in diseased individuals, drug inhibitors of cell wall synthesis such as isoniazid (INH) are employed. However, whether INH presents an indirect effect on bacterial growth by regulating host cytokines during ATB is not well known. To examine this hypothesis, we used an in vitro human granuloma system generated with primary leukocytes from healthy donors adapted to model ATB. Intense Mtb proliferation in cell cultures was associated with monocyte/macrophage activation and secretion of IL-1ß and TNF. Treatment with INH significantly reduced Mtb survival, but altered neither T-cell-mediated Mtb killing, nor production of IL-1ß and TNF. However, blockade of both IL-1R1 and TNF signaling rescued INH-induced killing, suggesting synergistic roles of these cytokines in mediating control of Mtb proliferation. Additionally, mycobacterial killing by INH was highly dependent upon drug activation by the pathogen catalase-peroxidase KatG and involved a host PI3K-dependent pathway. Finally, experiments using coinfected (KatG-mutated and H37Rv strains) cells suggested that active INH does not directly enhance host-mediated killing of Mtb. Our results thus indicate that Mtb-stimulated host IL-1 and TNF have potential roles in TB chemotherapy.

First insight into the molecular epidemiology of Mycobacterium tuberculosis in Santa Catarina, southern Brazil.

Molecular epidemiology of Mycobacterium tuberculosis is useful for understanding disease transmission dynamics, and to establish strategic measures for TB control and prevention. The aim of this study was to analyze clinical, epidemiological and molecular characteristics of MTBC clinical isolates from Santa Catarina state, southern Brazil. During one-year period, 406 clinical isolates of MTBC were collected from Central Laboratory of Public Health and typed by spoligotyping. Demographic and clinical data were collected from the Brazilian National Mandatory Disease Reporting System. The majority of cases occurred in highest population densities regions and about 50% had some condition associated with TB. Among all isolates, 5.7% were MDR, which showed association with drug addiction. LAM was the most predominant lineage with 47.5%, followed by the T superfamily with 25.9% and Haarlem with 12.3%. The MST showed two major groups: the first was formed mainly by the LAM lineage and the second was mainly formed by the T and Haarlem lineages. Others lineages were distributed in peripheral positions. This study provides the first insight into the population structure of M. tuberculosis in SC State. Spoligotyping and other genotyping analyses are important to establish strategic measures for TB control and prevention.

Molecular profiling of drug resistant isolates ofMycobacterium tuberculosis in the state of Santa Catarina, southern Brazil

Drug resistance is a global threat and one of the main contributing factors to tuberculosis (TB) outbreaks. The goal of this study was to analyse the molecular profile of multidrug-resistant TB (MDR-TB) in the state of Santa Catarina in southern Brazil. Fifty-three MDR Mycobacterium tuberculosisclinical isolates were analysed by spoligotyping and a partial region of therpoB gene, which is associated with rifampicin resistance (RMP-R), was sequenced. Some isolates were also distinguished by their mycobacterial interspersed repetitive units (MIRU). S531L was the most prevalent mutation found within rpoBin RMP-R isolates (58.5%), followed by S531W (20.8%). Only two MDR isolates showed no mutations withinrpoB. Isolates of the Latin American Mediterranean (LAM) family were the most prevalent (45.3%) found by spoligotyping, followed by Haarlem (9.4%) and T (7.5%) families. SIT106 was found in 26.4% of isolates and all SIT106 isolates typed by MIRU-12 (5 out of 14) belong to MIT251. There was a high correlation between the S531W mutation and the LAM family mainly because all SIT2263 (LAM9) isolates carry this mutation. Among isolates with the S531W mutation in rpoB MIRU demonstrates a cluster formed by four isolates (SIT2263 and MIT163) and very similar profiles were observed between eight of the nine isolates. Better characterisation of TB isolates may lead to new ways in which to control and treat TB in this region of Brazil.

Molecular profiling of drug resistant isolates of Mycobacterium tuberculosis in the state of Santa Catarina, southern Brazil.

Drug resistance is a global threat and one of the main contributing factors to tuberculosis (TB) outbreaks. The goal of this study was to analyse the molecular profile of multidrug-resistant TB (MDR-TB) in the state of Santa Catarina in southern Brazil. Fifty-three MDR Mycobacterium tuberculosis clinical isolates were analysed by spoligotyping and a partial region of the rpoB gene, which is associated with rifampicin resistance (RMP-R), was sequenced. Some isolates were also distinguished by their mycobacterial interspersed repetitive units (MIRU). S531L was the most prevalent mutation found within rpoB in RMP-R isolates (58.5%), followed by S531W (20.8%). Only two MDR isolates showed no mutations within rpoB. Isolates of the Latin American Mediterranean (LAM) family were the most prevalent (45.3%) found by spoligotyping, followed by Haarlem (9.4%) and T (7.5%) families. SIT106 was found in 26.4% of isolates and all SIT106 isolates typed by MIRU-12 (5 out of 14) belong to MIT251. There was a high correlation between the S531W mutation and the LAM family mainly because all SIT2263 (LAM9) isolates carry this mutation. Among isolates with the S531W mutation in rpoB MIRU demonstrates a cluster formed by four isolates (SIT2263 and MIT163) and very similar profiles were observed between eight of the nine isolates. Better characterisation of TB isolates may lead to new ways in which to control and treat TB in this region of Brazil.

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria.

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.

Relação entre a qualidade de amostras de escarro e o diagnóstico de micobacterioses por PCR / Relation between sputum samples quality and (PCR) for the diagnosis of micobacterioses

O objetivo do estudo foi relacionar a quantidade de células, a presença de leucócitos e outros elementos no escarro com a positividade da reação de PCR, para diagnóstico de micobacterioses. Trinta e nove amostras positivas por baciloscopia para bacilos álcool-ácido resistentes (BAAR), ou positivas em cultura em meio de Lõwenstein-Jensen foram analisadas pelo método de coloração de Gram, para avaliação da biota e quantificação de células e leucócitos. Foram também submetidas à reação de PCR, para identificação de micobactérias.As amostras, de acordo com os resultados do Gram, foram classificadas como: ótima, boa, aceitável, ruim ou muito ruim. Do total de amostras analisadas, 26 (66,7%) apresentaram PCR positiva concordando com a baciloscopia, 12 (30,7%) PCR negativa e baciloscopia ou cultura positiva e uma (2,6%) amostra não pôde ter seu resultado avaliado, pois o DNA apresentou-se degradado após sucessivas extrações. Dentre as amostras com PCR negativo e baciloscopia ou cultura positiva, 9 (23,0%) apresentaram qualidade muito ruim no Gram, 2 (5,2%) qualidade ruim e 1 (2,6%) apresentou qualidade aceitável. Os resultados mostraram que a qualidade do escarro influencia diretamente na positividade da PCR e que, quanto mais representativa do trato respiratório inferior for a amostra, melhor será o rendimento da detecção molecular...

Perfil de resistência de M. tuberculosis isolados de pacientes portadores do HIV/AIDS atendidos em um hospital de referência / M. tuberculosis resistance profile in HIV/AIDS patient in a reference hospital

Estudo realizado em 117 pacientes infectados pelo HIV internados em hospital de referência, no período de um ano, compreendido entre 1/10/95 a 30/9/96. Todos os pacientes tinham idade iqual ou superior a 15 anos e se submeteram à coleta de escarro para pesquisa de BAAR, por indicaçäo clínica. Todas as 117 amostras coletadas foram submetidas à baciloscopia, 116 à cultura (ocorreu contaminaçäo em uma amostra) e teste de sensibilidade em todas as 39 cepas isoladas. As cepas foram avaliadas pelos testes de PNB e TCH e em seguida encaminhadas a um centro de referência laboratorial para tipificaçäo da espécie. A baciloscopia foi positiva em 34,2 por cento (40/117) das amostras. Entre as 39 cepas isoladas, três näo pertenciam ao complexo M. tuberculosis (M. avium intarcelulares em duas e näo identificada em uma). a taxa de resistência atribuída ao M. tuberculosis isoladamente foi de 13,90 por cento (5/36). Näo foi encontrada resistência atribuída a uma única droga e a combinaçäo responsável pela maior taxa de resistência foi a de rifampicina com isoniazida. A resistência primária e secundária foi, respectivamente, de 20 por cento (4/20) e de 9,1 por cento (1/10). Entre os aspectos sociodemográfico e cínicos, a resistência às drogas esteve significativamente associada apenas a maior número de internaçöes prévia (p < 0,03). Esses dados sugerem uma possível transmissäo intra-hospitalar de cepas multirresistentes entre pacientes infectados pelo HIV