Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 45
Filtrar
1.
J Med Microbiol ; 70(3)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33625351

RESUMO

Introduction. Drug resistant tuberculosis remains a worldwide problem that requires prompt diagnosis.Hypothesis/Gap statement. The WHO recommended direct, rapid Xpert MTB/RIF is prohibitively costly, therefore, there is a need to validate a rapid, affordable DST for use in low- and middle-income settings.Aim. The technical performance and time to results of a simple, direct microscopy-based slide DST (SDST) assay for diagnosis of rifampicin-resistant TB was evaluated in Uganda.Methodology. Sputum samples from 122 smear-positive re-treatment TB patients presenting to the TB treatment centre at Uganda's National Referral Hospital, Mulago, Kampala, Uganda were examined. The sputum samples were tested by the direct SDST which was compared to the indirect Lowenstein Jensen Proportion Method (LJDST) method as the gold standard. The time to results was defined as the time from DST setting to results interpretation. The results were further analysed for sensitivity and specificity as well as agreement between LJDST and SDST for rifampicin resistance determination.Results. A total of 117 smear positive sputum samples with valid results for both tests were compared. The median time to results for SDST was 14 days with an interquartile range (IQR) of 10-14 days compared to 60 days with IQR of 60-75 days for LJDST. The number for rifampicin resistance by the gold standard LJDST was 26. The SDST had a sensitivity of 96 % (95 %; CI 81-99 %) and a specificity of 97.8 % (95 %; CI 93-100 %). The Positive Predictive and Negative Predictive values for SDST were 92.3 % (95 %; CI 76.8-99 %) and 98.9 % (95 %; CI 94-100 %), respectively. The kappa agreement between SDST and LJDST was 92.3 %.Conclusion. The SDST was found to be a rapid and accurate direct test for the detection of rifampicin resistance among retreatment TB cases in low-income settings.


Assuntos
Antibióticos Antituberculose/farmacologia , Resistência Microbiana a Medicamentos , Testes de Sensibilidade Microbiana/métodos , Mycobacterium tuberculosis/isolamento & purificação , Rifampina/farmacologia , Tuberculose/diagnóstico , Adulto , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana/normas , Microscopia , Pessoa de Meia-Idade , Mycobacterium tuberculosis/efeitos dos fármacos , Sensibilidade e Especificidade , Escarro/microbiologia , Fatores de Tempo , Uganda
2.
BMC Infect Dis ; 21(1): 63, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33435896

RESUMO

BACKGROUND: Chest X-ray (CXR) interpretation remains a central component of the current World Health Organization recommendations as an adjuvant test in diagnosis of smear-negative tuberculosis (TB). With its low specificity, high maintenance and operational costs, utility of CXR in diagnosis of smear-negative TB in high HIV/TB burden settings in the Xpert MTB/RIF era remains unpredictable. We evaluated accuracy and additive value of CXR to Xpert MTB/RIF in the diagnosis of TB among HIV-positive smear-negative presumptive TB patients. METHODS: HIV co-infected presumptive TB patients were recruited from the Infectious Diseases Institute outpatient clinic and in-patient medical wards of Mulago Hospital, Uganda. CXR films were reviewed by two independent radiologists using a standardized evaluation form. CXR interpretation with regard to TB was either positive (consistent with TB) or negative (normal or unlikely TB). Sensitivity, specificity and predictive values of CXR and CXR combined with Xpert MTB/RIF for diagnosis of smear-negative TB in HIV-positive patients were calculated using sputum and/or blood mycobacterial culture as reference standard. RESULTS: Three hundred sixty-six HIV co-infected smear-negative participants (female, 63.4%; hospitalized, 68.3%) had technically interpretable CXR. Median (IQR) age was 32 (28-39) years and CD4 count 112 (23-308) cells/mm3. Overall, 22% (81/366) were positive for Mycobacterium tuberculosis (Mtb) on culture; 187/366 (51.1%) had CXR interpreted as consistent with TB, of which 55 (29.4%) had culture-confirmed TB. Sensitivity and specificity of CXR interpretation in diagnosis of culture-positive TB were 67.9% (95%CI 56.6-77.8) and 53.7% (95%CI 47.7-59.6) respectively, while Xpert MTB/RIF sensitivity and specificity were 65.4% (95%CI 54.0-75.7) and 95.8% (95%CI 92.8-97.8) respectively. Addition of CXR to Xpert MTB/RIF had overall sensitivity and specificity of 87.7% (95%CI 78.5-93.9) and 51.6% (95%CI 45.6-57.5) respectively; 86.2% (95%CI 75.3-93.5) and 48.1% (95%CI 40.7-55.6) among inpatients and 93.8% (95%CI 69.8-99.8) and 58.0% (95%CI 47.7-67.8) among outpatients respectively. CONCLUSION: In this high prevalence TB/HIV setting, CXR interpretation added sensitivity to Xpert MTB/RIF test at the expense of specificity in the diagnosis of culture-positive TB in HIV-positive individuals presenting with TB symptoms and negative smear. CXR interpretation may not add diagnostic value in settings where Xpert MTB/RIF is available as a TB diagnostic tool.


Assuntos
Infecções Oportunistas Relacionadas com a AIDS/complicações , Coinfecção/diagnóstico , HIV/isolamento & purificação , Radiografia Pulmonar de Massa/métodos , Mycobacterium tuberculosis/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , Tuberculose Pulmonar/complicações , Tuberculose Pulmonar/diagnóstico , Infecções Oportunistas Relacionadas com a AIDS/epidemiologia , Infecções Oportunistas Relacionadas com a AIDS/virologia , Adulto , Contagem de Linfócito CD4 , Coinfecção/epidemiologia , Coinfecção/virologia , Confiabilidade dos Dados , Feminino , Recursos em Saúde , Humanos , Masculino , Sensibilidade e Especificidade , Escarro/microbiologia , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/microbiologia , Uganda/epidemiologia
3.
Nat Commun ; 11(1): 2917, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32518235

RESUMO

The human- and animal-adapted lineages of the Mycobacterium tuberculosis complex (MTBC) are thought to have expanded from a common progenitor in Africa. However, the molecular events that accompanied this emergence remain largely unknown. Here, we describe two MTBC strains isolated from patients with multidrug resistant tuberculosis, representing an as-yet-unknown lineage, named Lineage 8 (L8), seemingly restricted to the African Great Lakes region. Using genome-based phylogenetic reconstruction, we show that L8 is a sister clade to the known MTBC lineages. Comparison with other complete mycobacterial genomes indicate that the divergence of L8 preceded the loss of the cobF genome region - involved in the cobalamin/vitamin B12 synthesis - and gene interruptions in a subsequent common ancestor shared by all other known MTBC lineages. This discovery further supports an East African origin for the MTBC and provides additional molecular clues on the ancestral genome reduction associated with adaptation to a pathogenic lifestyle.


Assuntos
Genoma Bacteriano , Mycobacterium tuberculosis/classificação , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Idoso , DNA Bacteriano/genética , Evolução Molecular , Variação Genética , Genômica , Genótipo , Humanos , Funções Verossimilhança , Limite de Detecção , Masculino , Mutação , Mycobacterium tuberculosis/isolamento & purificação , Fenótipo , Filogenia , Rifampina/farmacologia , Ruanda , Uganda
4.
J Clin Microbiol ; 58(9)2020 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-32493780

RESUMO

Childhood tuberculosis (TB) presents significant diagnostic challenges associated with paucibacillary disease and requires a more sensitive test. We evaluated the diagnostic accuracy of Xpert MTB/RIF Ultra (Ultra) compared to other microbiological tests using respiratory samples from Ugandan children in the SHINE trial. SHINE is a randomized trial evaluating shorter treatment in 1,204 children with minimal TB disease in Africa and India. Among 352 samples and one cervical lymph node fine needle aspirate, one sample was randomly selected per patient and tested with the Xpert MTB/RIF assay (Xpert) and with Lowenstein-Jensen medium (LJ) and liquid mycobacterial growth indicator tube (MGIT) cultures. We selected only uncontaminated stored sample pellets for Ultra testing. We estimated the sensitivity of Xpert and Ultra against culture and a composite microbiological reference standard (any positive result). Of 398 children, 353 (89%) had culture, Xpert, and Ultra results. The median age was 2.8 years (interquartile range [IQR], 1.3 to 5.3); 8.5% (30/353) were HIV infected, and 54.4% (192/353) were male. Of the 353, 31 (9%) were positive by LJ and/or MGIT culture, 36 (10%) by Ultra, and 16 (5%) by Xpert. Sensitivities (95% confidence intervals [CI]) were 58% (39 to 65% [18/31]) for Ultra and 45% (27 to 64% [14/31]) for Xpert against any culture-positive result, with false positives of <1% and 5.5% for Xpert and Ultra. Against a composite microbiological reference, sensitivities were 72% (58 to 84% [36/50]) for Ultra and 32% (20 to 47% [16/50]) for Xpert. However, there were 17 samples that were positive only with Ultra (majority trace). Among children screened for minimal TB in Uganda, Ultra has higher sensitivity than Xpert. This represents an important advance for a condition which has posed a diagnostic challenge for decades.

5.
PLoS One ; 15(5): e0232543, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32413052

RESUMO

INTRODUCTION: Susceptibility testing for pyrazinamide (PZA), a cornerstone anti-TB drug is not commonly done in Uganda because it is expensive and characterized with technical difficulties thus resistance to this drug is less studied. Resistance is commonly associated with mutations in the pncA gene and its promoter region. However, these mutations vary geographically and those conferring phenotypic resistance are unknown in Uganda. This study determined the prevalence of PZA resistance and its association with pncA mutations. MATERIALS AND METHODS: Using a cross-sectional design, archived isolates collected during the Uganda national drug resistance survey between 2008-2011 were sub-cultured. PZA resistance was tested by BACTEC Mycobacterial Growth Indicator Tube (MGIT) 960 system. Sequence reads were downloaded from the NCBI Library and bioinformatics pipelines were used to screen for PZA resistance-conferring mutations. RESULTS: The prevalence of phenotypic PZA resistance was found to be 21%. The sensitivity and specificity of pncA sequencing were 24% (95% CI, 9.36-45.13%) and 100% (73.54% - 100.0%) respectively. We identified four mutations associated with PZA phenotypic resistance in Uganda; K96R, T142R, R154G and V180F. CONCLUSION: There is a high prevalence of phenotypic PZA resistance among TB patients in Uganda. The low sensitivity of pncA gene sequencing confirms the already documented discordances suggesting other mechanisms of PZA resistance in Mycobacterium tuberculosis.


Assuntos
Amidoidrolases/genética , Antituberculosos/uso terapêutico , Mycobacterium tuberculosis/efeitos dos fármacos , Pirazinamida/uso terapêutico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Pulmonar/tratamento farmacológico , Farmacorresistência Bacteriana Múltipla/genética , Humanos , Testes de Sensibilidade Microbiana , Mutação , Mycobacterium tuberculosis/genética , Prevalência , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Tuberculose Pulmonar/microbiologia , Uganda/epidemiologia
6.
J Clin Tuberc Other Mycobact Dis ; 14: 16-18, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31720413

RESUMO

Tuberculosis is the leading infectious cause of death globally and extra-pulmonary disease occurs in 15% of incident cases annually. Tuberculous meningitis (TBM) is arguably the most lethal form of tuberculosis and requires prompt diagnosis and initiation of treatment to prevent death and serious neurological disability. The development of rapid diagnostic tests using polymerase chain reaction (PCR) technology for the detection of Mycobacterium tuberculosis (MTB), including the World Health Organization (WHO) - endorsed Xpert MTB/RIF Ultra assay, has allowed earlier definite diagnosis of TBM than conventional culture methods which usually take two weeks or longer for positive identification of MTB. Detection of MTB in cerebrospinal fluid (CSF) using PCR assays requires special attention to the collection, handling, and processing of CSF. Herein we present best practices guidance to maximize the detection rate of MTB in CSF using Xpert MTB/RIF Ultra.

7.
Sci Rep ; 9(1): 11826, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31413308

RESUMO

We compared the ability of commercial and non-commercial, phenotypic and genotypic rapid drug susceptibility tests (DSTs) to detect rifampicin resistance (RR)-conferring 'disputed' mutations frequently missed by Mycobacterium Growth Indicator Tube (MGIT), namely L430P, D435Y, L452P, and I491F. Strains with mutation S450L served as positive control while wild-types were used as negative control. Of the 38 mutant strains, 5.7% were classified as RR by MGIT, 16.2% by Trek Sensititre MYCOTB MIC plate, 19.4% by resazurin microtiter plate assay (REMA), 50.0% by nitrate reductase assay (NRA), and 62.2% by microscopic observation direct susceptibility testing (MODS). Reducing MGIT rifampicin concentration to 0.5 µg/ml, and/or increasing incubation time, enhanced detection of disputed mutations from 5.7% to at least 65.7%, particularly for mutation I491F (from 0.0 to 75.0%). Compared with MGIT at standard pre-set time with 0.25 µg/ml ECOFF as breakpoint, we found a statistically significant increase in the ability of MGIT to resolve disputed mutants and WT strains at extended incubation period of 15 and 21 days, with 0.5 µg/ml and 1 µg/ml ECOFF respectively. MODS detected 75.0% of the I491F strains and NRA 62.5%, while it was predictably missed by all molecular assays. Xpert MTB/RIF, Xpert Ultra, and GenoscholarTB-NTM + MDRTB detected all mutations within the 81 bp RR determining region. Only GenoType MTBDRplus version 2 missed mutation L430P in 2 of 11 strains. Phenotypic and genotypic DSTs varied greatly in detecting occult rifampicin resistance. None of these methods detected all disputed mutations without misclassifying wild-type strains.


Assuntos
Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Farmacorresistência Bacteriana/genética , Mutação , Mycobacterium tuberculosis/genética , Rifampina/farmacologia , Antituberculosos , Proteínas de Bactérias/efeitos dos fármacos , RNA Polimerases Dirigidas por DNA/efeitos dos fármacos , Genes Bacterianos , Genótipo , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/efeitos dos fármacos
8.
PLoS One ; 14(6): e0217900, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31170234

RESUMO

BACKGROUND: Tuberculosis (TB) is the 9th leading cause of death from a single infectious agent. Patients live in a complex health care system with both formal and informal providers, and it is important that a TB diagnosis is not missed at the first interaction with the health care system. In this study, we highlight the health seeking behavior of patients and missed opportunities for early TB diagnosis for which interventions could be instituted to ensure early TB diagnosis and prompt TB treatment initiation. METHODS: This study was nested in a cross-sectional study that assessed the accuracy of different Xpert MTB/Rif implementation strategies in programmatic settings at the referral hospitals in Uganda. We documented the symptom profile of presumptive TB patients and assessed the health seeking behavior of those with chronic cough by calculating proportion of patients that visited each type of health facility and further calculated the odds of being TB positive given the type of health facility initially visited for consultation. RESULTS: A total of 1,863 presumptive TB patients were enrolled of which 979 (54.5%) were male, and 1795 (99.9%) had chronic cough. A total of 1352 (75.4%) had previously sought care for chronic cough, with 805 (59.6%) seeking care from a public health facility followed by private health facility (289; 21.4%). Up to 182 (13.5%) patients visited a drug store for chronic cough. Patients whose first contact was a private health facility were more likely to have a positive GeneXpert test (adjOR 1.4, 95% CI: 1.0-1.9; p = 0.047). CONCLUSIONS: Chronic cough is a main symptom for many of the presumptive TB patients presenting at referral hospitals, with several patients having to visit the health system more than once before a TB diagnosis is made. This suggests the need for patients to be thoroughly evaluated at first interface with the health care system to ensure prompt diagnosis and treatment initiation. Improved TB diagnosis possibly with the GeneXpert test, at first contact with the health care system has potential to increase TB case finding and break the transmission cycle in the community.


Assuntos
Tosse/complicações , Aceitação pelo Paciente de Cuidados de Saúde , Encaminhamento e Consulta , Tuberculose/diagnóstico , Tuberculose/etiologia , Adolescente , Adulto , Doença Crônica , Feminino , Instalações de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Probabilidade , Uganda/epidemiologia , Adulto Jovem
9.
PLoS One ; 14(5): e0216901, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31091275

RESUMO

BACKGROUND: Determining mycobacterial burden is important in assessing severity of disease, evaluating infectiousness and predicting patient treatment outcomes. Mycobacterial burden assessed by smear microscopy grade and time to culture positivity is clearly interpretable by most physicians. GeneXpert (Xpert) has been recommended by WHO as a first line tuberculosis (TB) diagnostic test as an alternative to smear microscopy. Xpert gives cycle threshold (Ct) values as a potential measure for mycobacterial burden. For physicians to clearly interpret Ct values as measures of mycobacterial burden, this study compared the Xpert quantification capabilities with those of smear microscopy and culture. The study also determined a linear relationship between Xpert Ct values and MGIT culture time to positivity (MGIT-TTP) and associated factors. A cut off Ct value which best predicts smear positivity was also determined using the Receiver Operator Curve analysis method. RESULTS: Excluding missing results and rifampicin resistant TB cases, a moderately strong correlation of 0.55 between Xpert Ct value and smear grade was obtained. A weak correlation of 0.37 was obtained between Xpert Ct values and MGIT time to positivity while that between Xpert Ct values and LJ culture was 0.34. The Xpert Ct values were found to increase by 2.57 for every unit increase in days to positive and HIV status was significantly associated with this relationship. A cut off Ct value of 23.62 was found to best predict smear positivity regardless of HIV status. CONCLUSION: Our study findings show that GeneXpert Ct values are comparable to smear microscopy as a measure of M. tuberculosis burden and can be used to replace smear microscopy. However, given the low correlation between Xpert Ct value and culture positivity, Xpert Ct values cannot replace culture as a measure of M. tuberculosis burden among TB patients.


Assuntos
Efeitos Psicossociais da Doença , Mycobacterium tuberculosis , Tuberculose Resistente a Múltiplos Medicamentos/diagnóstico , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tuberculose Resistente a Múltiplos Medicamentos/epidemiologia , Tuberculose Pulmonar/epidemiologia , Uganda/epidemiologia
11.
Am J Trop Med Hyg ; 100(2): 386-391, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30594259

RESUMO

Understanding risk factors for tuberculosis (TB) and their prevalence helps guide early diagnosis. We determined their prevalence among bacteriologically negative and bacteriologically confirmed TB patients in five regional referral hospitals in Uganda. This cross-sectional study considered 1,862 adult presumptive TB participants. We performed fluorescent microscopy, Xpert MTB/RIF (Xpert), Lowenstein-Jensen culture, human immunodeficiency virus, and random blood sugar testing on recruited patients. Prevalence and prevalence ratios of risk factors were compared among bacteriologically negative and confirmed cases. Odds ratios and 95% confidence interval (CI) were determined for significant risk factors in bacteriologically confirmed patients. Of the 1,862 participants, 978 (55%) were male and the median age of the participants was 36 years (interquartile range: 27-48). Up to 273 (15%) had a positive result on all three TB tests. Most prevalent risk factors (prevalence ratio [PR] > 1.0) among bacteriologically negative and positive TB patients were cigarette smoking (9.3% versus 2.1%; PR = 2.1), biosmoke (24% versus 39.7%; PR = 1.7), contact (4.2% versus 6.5%; PR = 1.6), male gender (51.4% versus 72.5%; PR = 1.4), alcohol use (17.2% versus 24.4%; PR = 1.4), diabetes (0.7% versus 0.9%; PR = 1.3), and family history of TB (12.1% versus 13.7%; PR = 1.1). The risk factors and their adjusted prevalence rate ratios (95% CI) of being bacteriologically positive were male (1.8 [1.4-2.4]), biosmoke exposure (1.5 [1.2-2.0]), and history of cigarette smoking (1.6 [1.1-2.4]). Among bacteriologically confirmed patients in Uganda, cigarette smoking, biosmoke exposure, contact, male gender, alcohol use, diabetes, and family history of TB are important risk factors for TB. Interventions for TB control in people with these risk factors would help in TB control efforts.


Assuntos
Consumo de Bebidas Alcoólicas/fisiopatologia , Fumar Cigarros/fisiopatologia , Diabetes Mellitus/fisiopatologia , Infecções por HIV/epidemiologia , Lesão por Inalação de Fumaça/fisiopatologia , Tuberculose Pulmonar/epidemiologia , Adulto , Glicemia/metabolismo , Coinfecção , Estudos Transversais , Feminino , HIV/crescimento & desenvolvimento , HIV/patogenicidade , Infecções por HIV/sangue , Infecções por HIV/diagnóstico , Infecções por HIV/virologia , Hospitais , Humanos , Masculino , Anamnese/estatística & dados numéricos , Pessoa de Meia-Idade , Mycobacterium tuberculosis/patogenicidade , Mycobacterium tuberculosis/fisiologia , Prevalência , Fatores de Risco , Fatores Sexuais , Escarro/microbiologia , Escarro/virologia , Tuberculose Pulmonar/sangue , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/microbiologia , Uganda/epidemiologia
12.
PLoS One ; 13(6): e0199638, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29953491

RESUMO

INTRODUCTION: Although Sensititre Mycobacterium tuberculosis (MYCOTB) plate offers both drug susceptibility testing (DST) and minimum inhibitory concentration (MIC) results, it has not been evaluated against both Lowenstein Jensen (LJ) and Middlebrook 7H10 (MB7H10) DST methods at standard critical concentrations. MATERIALS AND METHODS: We analyzed 76 M. tuberculosis isolates consisting of 54 isolates from the Uganda National TB drug resistance survey done December 2009-February 2011 and 22 isolates from the World Health Organization External Quality Assessment panel for the year 2011. All isolates were tested for LJ, MB7H10 and MYCOTB plate based DSTs for streptomycin, isoniazid, rifampicin and ethambutol anti-tuberculosis drugs. The agreement of MB7H10 with LJ and accuracy of MYCOTB plate using either LJ-DST or MB7H10 as a reference standard were determined. RESULTS: The agreement (kappa) of MB7H10 with LJ was; 0.687 for rifampicin, 0.498 for isoniazid, 0.275 for streptomycin and 0.082 for ethambutol which as almost similar when compared with MYCOTB plate. The sensitivity (95% confidence interval; CI) of MYCOTB plate when LJ was used as a reference standard was higher for streptomycin 87.5% (81.6-98.4) followed by isoniazid 75.9% (65.1-95.6) and rifampicin 73.1% (52.2-88.4). When MB7H10 was used as reference standard, the sensitivity of MYCOTB plate improved significantly; isoniazid 96.2% (80.3-99.9), rifampicin 94.0 (83.4-98.7) and 93.8% (69.7-99.8). There was good agreement between MYCOTB plate and MB7H10; 1.00 for ethambutol, 0.959 for streptomycin, 0.915 for rifampicin and 0.778 for isoniazid. CONCLUSIONS: The performance of the two culture-based reference standards for phenotypic first-line drug susceptibility testing methods, LJ and MB7H10, varied much even with acceptable MYCOTB plate MICs. There was acceptable agreement and accuracy of MYCOTB plate for drug susceptibility testing when MB7H10 was used as reference standard than with LJ-DST. Results from MIC information makes the MYCOTB plate more suitable for guiding clinicians on the choice of the most appropriate TB treatment regimen as well as limits of detection for TB drug resistance.


Assuntos
Antituberculosos/farmacologia , Testes de Sensibilidade Microbiana/instrumentação , Mycobacterium tuberculosis/efeitos dos fármacos , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana/métodos , Testes de Sensibilidade Microbiana/normas , Mycobacterium tuberculosis/isolamento & purificação , Padrões de Referência , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia
13.
PLoS One ; 13(3): e0194741, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29566056

RESUMO

BACKGROUND: Xpert MTB/RIF assay is a highly sensitive test for TB diagnosis, but still costly to most low-income countries. Several implementation strategies instead of frontline have been suggested; however with scarce data. We assessed accuracy of different Xpert MTB/RIF implementation strategies to inform national roll-out. METHODS: This was a cross-sectional study of 1,924 adult presumptive TB patients in five regional referral hospitals of Uganda. Two sputum samples were collected, one for fluorescent microscopy (FM) and Xpert MTB/RIF examined at the study site laboratories. The second sample was sent to the Uganda Supra National TB reference laboratory for culture using both Lowenstein Jensen (LJ) and liquid culture (MGIT). We compared the sensitivities of FM, Xpert MTB/RIF and the incremental sensitivity of Xpert MTB/RIF among patients negative on FM using LJ and/or MGIT as a reference standard. RESULTS: A total 1924 patients were enrolled of which 1596 (83%) patients had at least one laboratory result and 1083 respondents had a complete set of all the laboratory results. A total of 328 (30%) were TB positive on LJ and /or MGIT culture. The sensitivity of FM was n (%; 95% confidence interval) 246 (63.5%; 57.9-68.7) overall compared to 52 (55.4%; 44.1-66.3) among HIV positive individuals, while the sensitivity of Xpert MTB/RIF was 300 (76.2%; 71.7-80.7) and 69 (71.6%; 60.5-81.1) overall and among HIV positive individuals respectively. Overall incremental sensitivity of Xpert MTB/RIF was 60 (36.5%; 27.7-46.0) and 20 (41.7%; 25.5-59.2) among HIV positive individuals. CONCLUSION: Xpert MTB/RIF has a higher sensitivity than FM both in general population and HIV positive population. Xpert MTB/RIF offers a significant increase in terms of diagnostic sensitivity even when it is deployed selectively i.e. among smear negative presumptive TB patients. Our results support frontline use of Xpert MTB/RIF assay in high HIV/TB prevalent countries. In settings with limited access, mechanisms to refer smear negative sputum samples to Xpert MTB/RIF hubs are recommended.


Assuntos
Técnicas de Diagnóstico Molecular , Mycobacterium tuberculosis/genética , Tuberculose Pulmonar/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Notificação de Doenças/métodos , Notificação de Doenças/normas , Prática Clínica Baseada em Evidências , Feminino , Implementação de Plano de Saúde/normas , Humanos , Masculino , Pessoa de Meia-Idade , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/normas , Mycobacterium tuberculosis/isolamento & purificação , Encaminhamento e Consulta/normas , Encaminhamento e Consulta/estatística & dados numéricos , Reprodutibilidade dos Testes , Centros de Cuidados de Saúde Secundários/estatística & dados numéricos , Sensibilidade e Especificidade , Tuberculose Pulmonar/microbiologia , Uganda/epidemiologia , Adulto Jovem
14.
BMC Infect Dis ; 18(1): 87, 2018 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-29466946

RESUMO

BACKGROUND: Smear microscopy lacks sensitivity especially in HIV co-infection, resulting in undiagnosed tuberculosis (TB) and high mortality. The loop-mediated isothermal amplification (TB-LAMP) assay can be staged with minimal infrastructure, is rapid, low cost and detection can be with the naked eye. We assessed feasibility and performance of Eiken TB-LAMP test at point-of-need in TB diagnosis in a high prevalence TB/HIV rural setting in Uganda. METHODS: From October 2013-February 2014, TB-LAMP testing was performed on sputum specimens from outpatient presumptive TB adults at a district hospital and two low-level health centers in Kiboga District where smear microscopy is the available routine diagnostic option. TB-LAMP was performed by a technician after a week of training in the district hospital. The technician had no prior experience in the technology. Samples from the low-level health centers were transported to the district hospital for TB-LAMP. RESULTS: Of the 233 presumptive TB (126 at hospital); 113 (48.5%) were HIV-infected; 129 (55%) male; median age 40 (IQR 30-53). Compared to MTB culture, overall sensitivity and specificity of TB-LAMP were 55.4% (95 CI 44.1-66.3) and 98.0% (95 CI 94.3-99.6) respectively. Among HIV-infected participants, TB-LAMP sensitivity and specificity were 52.3% (95 CI 36.7-67.5%) and 97.1% (95 CI 89.9-99.6) respectively; and 24.4% (95% CI 12.9-39.5) and 98.6% (95% CI 95.1-99.8) respectively among smear-negatives. TB-LAMP sensitivity and specificity were 62.2% (95% CI 44.8-77.5) and 97.8% (95% CI 92.1-99.7) in the hospital setting where central testing occurred compared to 50.0% (95% CI 34.9-65.1) and 98.4% (95% CI 91.2-100) respectively in low-level health centers where specimens were transported centrally. CONCLUSIONS: In this high prevalence TB/HIV rural setting, TB-LAMP performs better than conventional smear microscopy in diagnosis of MTB among presumptive TB patients although the sensitivity is lower than that reported by the World Health Organization. TB-LAMP can easily be performed following a short training period and in absence of sophisticated infrastructure and expertise.


Assuntos
Infecções por HIV/diagnóstico , Mycobacterium tuberculosis/genética , Tuberculose Pulmonar/diagnóstico , Adulto , Técnicas Bacteriológicas , Feminino , Infecções por HIV/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Mycobacterium tuberculosis/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico , Prevalência , População Rural , Sensibilidade e Especificidade , Escarro/microbiologia , Tuberculose Pulmonar/complicações , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/microbiologia , Uganda/epidemiologia
15.
Nat Genet ; 49(3): 395-402, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28092681

RESUMO

Multidrug-resistant tuberculosis (MDR-TB), caused by drug-resistant strains of Mycobacterium tuberculosis, is an increasingly serious problem worldwide. Here we examined a data set of whole-genome sequences from 5,310 M. tuberculosis isolates from five continents. Despite the great diversity of these isolates with respect to geographical point of isolation, genetic background and drug resistance, the patterns for the emergence of drug resistance were conserved globally. We have identified harbinger mutations that often precede multidrug resistance. In particular, the katG mutation encoding p.Ser315Thr, which confers resistance to isoniazid, overwhelmingly arose before mutations that conferred rifampicin resistance across all of the lineages, geographical regions and time periods. Therefore, molecular diagnostics that include markers for rifampicin resistance alone will be insufficient to identify pre-MDR strains. Incorporating knowledge of polymorphisms that occur before the emergence of multidrug resistance, particularly katG p.Ser315Thr, into molecular diagnostics should enable targeted treatment of patients with pre-MDR-TB to prevent further development of MDR-TB.


Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Mycobacterium tuberculosis/genética , Tuberculose Resistente a Múltiplos Medicamentos/genética , Antituberculosos/uso terapêutico , Proteínas de Bactérias/genética , Catalase/genética , Genômica/métodos , Humanos , Isoniazida/uso terapêutico , Mutação/genética , Mycobacterium tuberculosis/efeitos dos fármacos , Polimorfismo Genético/genética , Rifampina/uso terapêutico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico
16.
Nat Genet ; 48(12): 1535-1543, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27798628

RESUMO

Generalist and specialist species differ in the breadth of their ecological niches. Little is known about the niche width of obligate human pathogens. Here we analyzed a global collection of Mycobacterium tuberculosis lineage 4 clinical isolates, the most geographically widespread cause of human tuberculosis. We show that lineage 4 comprises globally distributed and geographically restricted sublineages, suggesting a distinction between generalists and specialists. Population genomic analyses showed that, whereas the majority of human T cell epitopes were conserved in all sublineages, the proportion of variable epitopes was higher in generalists. Our data further support a European origin for the most common generalist sublineage. Hence, the global success of lineage 4 reflects distinct strategies adopted by different sublineages and the influence of human migration.


Assuntos
DNA Bacteriano/análise , Genômica/métodos , Mycobacterium tuberculosis/classificação , Mycobacterium tuberculosis/genética , Polimorfismo Genético/genética , Tuberculose/microbiologia , Genótipo , Saúde Global , Humanos , Mycobacterium tuberculosis/isolamento & purificação , Filogeografia , Tuberculose/genética
17.
BMC Infect Dis ; 16(1): 660, 2016 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-27825314

RESUMO

BACKGROUND: Tuberculosis control program of Rwanda is currently phasing in light emitting diode-fluorescent microscopy (LED-FM) as an alternative to Ziehl-Neelsen (ZN) smear microscopy. This, alongside the newly introduced Xpert (Cepheid, Sunnyvale, CA, USA) is expected to improve diagnosis of tuberculosis and detection of rifampicin resistance in patients at health facilities. We assessed the accuracy of smear microscopy and the incremental sensitivity of Xpert at tuberculosis laboratories in Rwanda. METHODS: This was a cross-sectional study involving four laboratories performing ZN and four laboratories performing LED-FM microscopy. The laboratories include four intermediate (ILs) and four peripheral (PLs) laboratories. After smear microscopy, the left-over of samples, of a single early-morning sputum from 648 participants, were tested using Xpert and mycobacterial culture as a reference standard. Sensitivity of each test was compared and the incremental sensitivity of Xpert after a negative smear was assessed. RESULTS: A total of 96 presumptive pulmonary tuberculosis participants were culture positive for M. tuberculosis. The overall sensitivity in PL of ZN was 55.1 % (40.2-69.3 %), LED-FM was 37 % (19.4-57.6 %) and Xpert was 77.6 % (66.6-86.4 %) whereas in ILs the same value for ZN was 58.3 % (27.7-84.8 %), LED-FM was 62.5 % (24.5-91.5 %) and Xpert was 90 (68.3-98.8 %). The sensitivity for all tests was significantly higher among HIV-negative individuals (all test p <0.05). The overall incremental sensitivity of Xpert over smear microscopy was 32.3 %; p < 0.0001. The incremental sensitivity of Xpert was statistically significant for both smear methods at PL (32.9 %; p = 0.001) but not at the ILs (30 %; p = 0.125) for both smear methods. CONCLUSIONS: Our study findings of the early implementation of the LED-FM did not reveal significant increment in sensitivity compared to the method being phased out (ZN). This study showed a significant incremental sensitivity for Xpert from both smear methods at peripheral centers where majority of TB patients are diagnosed. Overall our findings support the recommendation for Xpert as an initial diagnostic test in adults and children presumed to have TB.


Assuntos
Microscopia de Fluorescência/métodos , Tuberculose Pulmonar/diagnóstico , Adolescente , Adulto , Estudos Transversais , Testes Diagnósticos de Rotina , Farmacorresistência Bacteriana , Feminino , Instalações de Saúde , Humanos , Laboratórios , Masculino , Pessoa de Meia-Idade , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/patogenicidade , Rifampina/uso terapêutico , Ruanda , Sensibilidade e Especificidade , Escarro/microbiologia , Tuberculose Pulmonar/tratamento farmacológico , Tuberculose Pulmonar/microbiologia , Adulto Jovem
18.
PLoS One ; 11(9): e0162833, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27611466

RESUMO

INTRODUCTION: Early diagnosis and initiation to appropriate treatment is vital for tuberculosis (TB) control. The XpertMTB/RIF (Xpert) assay offers rapid TB diagnosis and quantitative estimation of bacterial burden through Cycle threshold (Ct) values. We assessed whether the Xpert Ct value is associated with delayed TB diagnosis as a potential monitoring tool for TB control programme performance. MATERIALS AND METHODS: This analysis was nested in a prospective study under the routine TB surveillance procedures of the National TB Control Program in Manhiça district, Maputo province, Mozambique. Presumptive TB patients were tested using smear microscopy and Xpert. We explored the association between Xpert Ct values and self-reported delay of Xpert-positive TB patients as recorded at the time of diagnosis enrolment. Patients with >60 days of TB symptoms were considered to have long delays. RESULTS: Of 1,483 presumptive TB cases, 580 were diagnosed as TB of whom 505 (87.0%) were due to pulmonary TB and 302 (94.1%) were Xpert positive. Ct values (range, 9.7-46.4) showed a multimodal distribution. The median (IQR) delay was 30 (30-45) days. Ct values showed no correlation with delay (R2 = 0.001, p = 0.621), nor any association with long delays: adjusted odds ratios (AOR) (95% confidence interval [CI]) comparing to >28 cycles 0.99 (0.50-1.96; p = 0.987) for 23-28 cycles, 0.93 (0.50-1.74; p = 0.828) for 16-22 cycles; and 1.05 (0.47-2.36; p = 0.897) for <16 cycles. Being HIV-negative (AOR [95% CI]), 2.05 (1.19-3.51, p = 0.009) and rural residence 1.74 (1.08-2.81, p = 0.023), were independent predictors of long delays. CONCLUSION: Xpert Ct values were not associated with patient delay for TB diagnosis and cannot be used as an indicator of TB control program performance.


Assuntos
Diagnóstico Tardio , Kit de Reagentes para Diagnóstico , Rifampina/uso terapêutico , Tuberculose/diagnóstico , Adulto , Demografia , Feminino , Humanos , Masculino , Análise Multivariada
19.
BMC Infect Dis ; 16: 371, 2016 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-27495002

RESUMO

BACKGROUND: In the context of advanced immunosuppression, M. tuberculosis is known to cause detectable mycobacteremia. However, little is known about the intra-patient mycobacterial microevolution and the direction of seeding between the sputum and blood compartments. METHODS: From a diagnostic study of HIV-infected TB patients, 51 pairs of concurrent blood and sputum M. tuberculosis isolates from the same patient were available. In a previous analysis, we identified a subset with genotypic concordance, based on spoligotyping and 24 locus MIRU-VNTR. These paired isolates with identical genotypes were analyzed by whole genome sequencing and phylogenetic analysis. RESULTS: Of the 25 concordant pairs (49 % of the 51 paired isolates), 15 (60 %) remained viable for extraction of high quality DNA for whole genome sequencing. Two patient pairs were excluded due to poor quality sequence reads. The median CD4 cell count was 32 (IQR; 16-101)/mm(3) and ten (77 %) patients were on ART. No drug resistance mutations were identified in any of the sequences analyzed. Three (23.1 %) of 13 patients had SNPs separating paired isolates from blood and sputum compartments, indicating evidence of microevolution. Using a phylogenetic approach to identify the ancestral compartment, in two (15 %) patients the blood isolate was ancestral to the sputum isolate, in one (8 %) it was the opposite, and ten (77 %) of the pairs were identical. CONCLUSIONS: Among HIV-infected patients with poor cellular immunity, infection with multiple strains of M. tuberculosis was found in half of the patients. In those patients with identical strains, whole genome sequencing indicated that M. tuberculosis intra-patient microevolution does occur in a few patients, yet did not reveal a consistent direction of spread between sputum and blood. This suggests that these compartments are highly connected and potentially seed each other repeatedly.


Assuntos
Sangue/microbiologia , Evolução Molecular , Infecções por HIV/microbiologia , Mycobacterium tuberculosis/genética , Escarro/microbiologia , Tuberculose/microbiologia , Infecções Oportunistas Relacionadas com a AIDS/microbiologia , Adulto , Técnicas de Tipagem Bacteriana/métodos , Sangue/virologia , Feminino , Genoma Bacteriano , Genótipo , Infecções por HIV/complicações , HIV-1 , Humanos , Sequências Repetitivas Dispersas , Masculino , Pessoa de Meia-Idade , Repetições Minissatélites , Mycobacterium tuberculosis/classificação , Mycobacterium tuberculosis/isolamento & purificação , Filogenia , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA/métodos , Tuberculose/complicações , Adulto Jovem
20.
Infect Genet Evol ; 40: 8-16, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26917365

RESUMO

Understanding the circulating Mycobacterium tuberculosis resistance mutations is vital for better TB control strategies, especially to inform a new MDR-TB treatment programme. We complemented the phenotypic drug susceptibility testing (DST) based drug resistance surveys (DRSs) conducted in Uganda between 2008 and 2011 with Whole Genome Sequencing (WGS) of 90 Mycobacterium tuberculosis isolates phenotypically resistant to rifampicin and/or isoniazid to better understand the extent of drug resistance. A total of 31 (34.4 %) patients had MDR-TB, 5 (5.6 %) mono-rifampicin resistance and 54 (60.0 %) mono-isoniazid resistance by phenotypic DST. Pyrazinamide resistance mutations were identified in 32.3% of the MDR-TB patients. Resistance to injectable agents was detected in 4/90 (4.4%), and none to fluoroquinolones or novel drugs. Compensatory mutations in rpoC were identified in two patients. The sensitivity and specificity of drug resistance mutations compared to phenotypic DST were for rpoB 88.6% and 98.1%, katG 60.0% and 100%, fabG1 16.5% and 100%, katG and/or fabG1 71.8% and 100%, embCAB 63.0% and 82.5%, rrs 11.4% and 100%, rpsL 20.5% and 95.7% and rrs and/or rpsL 31.8% and 95.7%. Phylogenetic analysis showed dispersed MDR-TB isolate, with only one cluster of three Beijing family from South West Uganda. Among tuberculosis patients in Uganda, resistance beyond first-line drugs as well as compensatory mutations remain low, and MDR-TB isolates did not arise from a dominant clone. Our findings show the potential use of sequencing for complementing DRSs or surveillance in this setting, with good specificity compared to phenotypic DST. The reported high confidence mutations can be included in molecular assays, and population-based studies can track transmission of MDR-TB including the Beijing family strains in the South West of the country.


Assuntos
Antituberculosos/farmacologia , Genoma Bacteriano , Mycobacterium tuberculosis/genética , Análise de Sequência de DNA/métodos , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Adulto , Proteínas de Bactérias/genética , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Mutação , Mycobacterium tuberculosis/classificação , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/isolamento & purificação , Filogenia , Pirazinamida/farmacologia , Rifampina/farmacologia , Uganda , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...