Frequency of tuberculous and non-tuberculous mycobacteria in HIV infected patients from Bogota, Colombia

First Case Reports of Nontuberculous Mycobacterial (NTM) Lung Disease in Ecuador: Important Lessons to Learn

Nontuberculous mycobacteria (NTM) lung infections are often misdiagnosed as tuberculosis, which can lead to ineffective antibiotic treatments. In this report, we present three cases of NTM lung infections in Ecuador that were initially diagnosed and treated as tuberculosis based on the results of sputum smear microscopy. The patients, all male, included two immunocompetent individuals and one HIV-positive subject. Unfortunately, sputum culture was not initiated until late in the course of the disease and the cause of the lung infection, Mycobacterium avium complex (MAC), was only identified after the patients had either passed away or were lost to follow-up. These cases are the first documented cases of NTM lung infections in the English medical literature from Ecuador. We emphasize the importance of accurate diagnosis of NTM infections by culture and identification to species level. Sputum smear staining alone cannot differentiate between mycobacterial species, which can lead to misidentification and ineffective treatments. Additionally, reporting NTM pulmonary disease as a notifiable disease to national TB control programs is recommended to obtain accurate prevalence data. These data are critical in determining the importance of this public health problem and the necessary actions needed to address it.

Non-tuberculous mycobacterial infections in geriatric patients-A neglected and emerging problem

The diseases caused by Non-tuberculous mycobacteria (NTM) has increased steadily in the last two decades. Increase in incidence of NTM infections are being reported in elderly people as they are more susceptible and often experiencing high morbidity. There is prediction that NTM infections will further rise because of expected increase in elderly population by 2050. Given the importance of NTM infection in the elderly, the interest in studying NTM characteristics in the aged population is increasing. In this review, we summarize the characteristics of NTM infection among elderly patients. We focus on epidemiology, clinical presentation, and treatment options of NTM in this age group. We highlight the differences in the diagnosis and treatment between rapid and slow growing mycobacterial infections. The current recommendations for treatment of NTM have been discussed. Finally, we have reviewed the prognosis of NTM disease in elderly patients.

Genetic diversity of Mycobacterium tuberculosis clinical isolates from HIV-TB patients from two public hospitals at Bogotá, Colombia

The co-infection of TB/HIV is an increasing problem for public health worldwide. In Colombia, of 13.871 confirmed cases of TB in 2016 (prevalence of 0,028%) 14% correspond to HIV co-infection. However, we have scarce information regarding genetic diversity of strains infecting HIV patients. In this study, we carried-out an active search of cases of TB in 356 HIV-infected individuals, who were enrolled in two Public Hospitals at Bogotá-Colombia, between 2014 and 2015. We found 49 patients with HIV-TB co-infection. Genetic characterization of Mycobacterium tuberculosis (Mtb) isolates from these patients showed a predominance of three major sub-lineages: Haarlem (n = 26), LAM (n = 12) and T (n = 11). Remarkably, the most predominant pattern in the present study (SIT62/H1, n = 11) is very specific to this country. Indeed, taking in account distribution in countries with at least 3% of SIT62/H1, 36% of all such patterns collected worldwide were from Colombia. Furthermore, Colombia alone is responsible for almost all the SIT62/H1 strains in South America, suggesting a successful transmission of this genotype inside TB/HIV population from Colombia.

Mycobacterium avium complex infection in patients with human immunodeficiency virus: A systematic review and meta-analysis

BACKGROUND

Mycobacterium avium-intracellulare complex (MAC) is one of the leading causes of death among people living with human immunodeficiency virus (HIV). The current study was aimed to determine the frequency of MAC infection in patients infected with HIV.

METHODS

Embase, PubMed, and Web of Science were searched for relevant studies. All statistical analyses were performed by STATA version 14.

RESULTS

From 6,627 retrieved articles, 23 were included in the final analysis. A total of 18,463 patients with HIV were included in the analysis. The frequency of MAC infection in patients with HIV was found to be 10.6% (95% confidence interval, 6.9-14.2).

CONCLUSION

The relatively large fractions of HIV-infected patients were coinfected with MAC, which may poses significant public health problems. Continued progress in the development of rapid diagnostic methods and preventive therapy for MAC should lead to further improvements in survival and quality of life in patients with HIV.

Mycobacterioses identified in the National Reference Laboratory of Colombia from 2012 to 2016

Introduction: In recent years, there has been an increase in the prevalence of mycobacterioses caused by non-tuberculous mycobacteria, which are considered as emerging pathogens. Their presence depends on several factors such as the clinical history, the health status of the affected person, and the presence of these microorganisms in the water, the soil, and the animals, among others. Objective: To describe the mycobacteria and the etiological agent identified in isolates received at the Laboratorio Nacional de Referencia de Micobacterias of the Instituto Nacional de Salud between 2012 and 2016. Materials and methods: We conducted a retrospective analysis of samples from 273 patients with mycobacterioses. We analyzed the following variables: mycobacteriosis type, etiological agent, and associated predisposing factors. Results: 57.1% of the cases presented pulmonary mycobacteriosis; 26%, cutaneous; 10.6%, disseminated, and 2.6%, lymphatic. We found the Mycobacterium avium complex more frequently in pulmonary mycobacteriosis, while M. abscessus was more frequent in the extrapulmonary types of the disease. Patients with pulmonary mycobacteriosis had a history of tuberculosis more frequently than those with extrapulmonary forms. Conclusion: These findings highlight the importance of the differential diagnosis between M. tuberculosis complex species and non-tuberculous mycobacteria since the latter are genetically resistant to conventional antituberculosis drugs.

[Prevalence and risk factors associated to tuberculosis and non-tuberculous mycobacterial infections in HIV-positive patients in Bogotá]

INTRODUCTION

Tuberculosis is one of the most widely distributed infectious diseases worldwide. It is the most common cause of mortality among AIDS patients. In Colombia, 12,918 tuberculosis cases were notified, and 926 deaths were reported in 2015.

OBJECTIVE

To determine the prevalence and risk factors associated to mycobacterial infections in HIVpositive patients in two public hospitals from Bogotá.

MATERIALS AND METHODS

A prospective and descriptive study was carried out by an active search for tuberculosis cases and non-tuberculous mycobacterial infections in HIV-positive patients. We considered demographic, social, clinical, and personal habits as variables. Statistical analyses were done using Stata 13™ software.

RESULTS

Three hundred and fifty six patients were included, 81.2% were men and 18.8% were women; the mean age was 36.5 years. Tuberculosis infection had a frequency of 19.9% (95% CI: 15.9-24.5%) and non-tuberculous mycobacterial infection had a 3.9% frequency (95% CI: 2.16-6.5%). Bivariate analysis showed a statistically significant association between tuberculosis infection and CD4+ T cell counts (p=0.003), viral load (p=0.008), antiretroviral therapy (p=0.014), and body mass index (BMI) <18 kg/m2 (p=0.000). In non-tuberculous mycobacterial infections there was a statistically significantassociation with BMI (p=0.027) and CD4+ T cell counts (p=0.045).

CONCLUSION

Factors associated with an impaired immune system caused by HIV infection are an important risk factor for developing tuberculosis. The lack of antiretroviral therapy and the BMI were also important risk factors for tuberculosis.

Routinely detected indicators in plasma have a predictive effect on the identification of HIV-infected patients with non-tuberculous mycobacterial and tuberculous infections

BACKGROUND

It is difficult to quickly distinguish non-tuberculous mycobacterial (NTM) infection from tuberculosis (TB) infection in human immunodeficiency virus (HIV)-infected patients because of many similarities between these diseases. A simple and effective way to determine the differences using routine blood tests is necessary in developing countries.

METHODS

A retrospective cohort study was conducted to recruit HIV-infected patients with either NTM infection or TB infection diagnosed for the first time according to mycobacterial culture and microscopic identification from May 2010 to March 2016. These data included the analysis of blood cells, liver function, renal function, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR), and were compared between the HIV/TB and HIV/NTM groups.

RESULTS

A total of 240 patients were enrolled. The number of HIV/TB and HIV/NTM patients was 113 and 127, respectively. There were no significant differences in the CD4 T-cell count, age, sex, percentage of patients initiating antiretroviral therapy (ART) before the explicit diagnosis of TB or NTM infection. NTM infection was more likely to be restricted in the pulmonary while TB infection also involves extra-pulmonary sites. Both the leukocyte count(5.60 × 109/L) and the proportion of neutrophils in the leukocyte count (76.70%) in the HIV/TB group were significantly higher than those in the HIV/NTM group (4.40 × 109/L [P = 0.0014] and 69.30% [P < 0.001]. The analysis of liver function markers indicated that the concentration of albumin but not ALT and AST was significantly lower in the HIV/TB group than in the HIV/NTM group (P < 0.001). The creatinine and urea levels were not significantly different between the two groups. The ESR (84.00 mm/h) and the concentration of CRP (59.60 mg/L) were significantly higher in the HIV/TB group than in the HIV/NTM group (52.00 mm/h and 19.60 mg/L, respectively) (P < 0.001). To distinguish TB infection from NTM infection, the best cut-off value was 69.5 mm/h for ESR, with a positive predictive value (PPV) of 0.740 and negative predictive value (NPV) of 0.721, and 48.8 mg/L for CRP, with a PPV of 0.676 and NPV of 0.697.

CONCLUSION

The dissemination character as well as stronger immune response characterized by higher inflammation markers (e.g. WBC, ESR, CRP) can help distinguish TB from NTM infection in HIV-infected patients who need empirical therapy or diagnostic therapy immediately in low-income areas.

Effect of vitamin A and vitamin C supplementation on oxidative stress in HIV and HIV-TB co-infection at Lagos University Teaching Hospital (LUTH) Nigeria

BACKGROUND

HIV and TB infections are both associated with elevated oxidative stress parameters. Anti-oxidant supplementation may offer beneficial effects in positively modulating oxidative stress parameters in HIV and HIV-TB infected patients. We investigated the effects of vitamin A and C supplementation on oxidative stress in HIV infected and HIV-TB co-infected subjects.

METHODS

40 HIV/TB co-infected and 50 HIV mono-infected patients were divided into 2 equal groups. Participants provided demographic information and blood was collected to determine oxidative stress parameters before and after vitamin A (5000 IU) and C (2600 mg) supplementation for 1 month.

RESULTS

There was a significantly (p < 0.05) higher level of Malondialdehyde (MDA) at baseline for HIV infected subjects compared with HIV-TB co-infected subjects. There was a significantly (p < 0.05) lower level of MDA and higher level of Catalase (CAT) in subjects administered supplementation compared to subjects without supplementation for the HIV infected group. There was a significantly lower level of Reduced Glutathione (GSH), Superoxide Dismutase (SOD) and higher level of MDA after one month of supplementation compared with baseline levels for HIV/TB co infected subjects. A similar result was also obtained for the HIV mono-infected groups which had a significantly lower level of SOD, MDA and CAT compared to the baseline. There was a significantly lower level of GSH and SOD, and higher level of MDA after supplementation compared with the baseline for HIV/TB co-infected subjects. Comparing the indices at baseline and post no-supplementation in HIV/TB co-infection showed no significant differences in the oxidative stress parameters.

CONCLUSION

HIV/TB co-infection and HIV mono-infection seems to diminish the capacity of the anti-oxidant system to control oxidative stress, however exogenous anti-oxidant supplementation appears not to have beneficial roles in positively modulating the associated oxidative stress.

A mycobacterial coinfection in a dog suspected on blood smear

A 4-year-old neutered female crossbred Shepherd was referred for a history of 10 days of anorexia, polyuria, polydipsia, polyadenomegaly, and diarrhea. On physical examination, the dog appeared quiet, responsive, and apyretic, with generalized and severe lymphadenomegaly. Hematologic abnormalities included neutrophilic leukocytosis with left shift, and lymphopenia. Blood smears revealed intracytoplasmic bacilli negatively stained with May-Grünwald-Giemsa in neutrophils and monocytes. Lymph node smears revealed pyogranulomatous adenitis with calcified deposits and many negative-staining rod structures, both within the cytoplasm of neutrophils and macrophages, and free in the background. An acid-fast stain (Ziehl-Neelsen) confirmed the diagnosis of mycobacterial infection. The dog was euthanized for public health and ethical reasons, and the postmortem examination revealed severe and generalized granulomatous and necrotizing lymphadenitis, panniculitis, and hepatitis, and infiltration of epithelioid macrophages in the lungs, colon, and spleen. Numerous acid-fast bacilli, consistent with mycobacterial infection, were observed both in the cytoplasm of epithelioid macrophages and giant cells, and free in the background. Mycobacterium bovis was first confirmed by conventional PCR of organ extracts. Mycobacterium avium was detected in a culture of the same organs. Further PCR amplifications and sequencing revealed a coinfection with 2 different species of mycobacterium, one belonging to the Mycobacterium avium complex and the other to the Mycobacterium tuberculosis complex.

[Identification of mycobacteria to the species level by molecular methods in the Public Health Laboratory of Bogotá, Colombia]

INTRODUCTION

Global epidemiology of non-tuberculous mycobacteria (NTM) is unknown due to the fact that notification is not required in many countries, however the number of infection reports and outbreaks caused by NTM suggest a significant increase in the last years. Traditionally, mycobacteria identification is made through biochemical profiles which allow to differentiate M. tuberculosis from NTM, and in some cases the mycobacteria species. Nevertheless, these methods are technically cumbersome and time consuming. On the other hand, the introduction of methods based on molecular biology has improved the laboratory diagnosis of NTM.

OBJECTIVE

To establish the NTM frequency in positive cultures for acid-fast bacilli (AAFB) which were sent to Laboratorio de Salud Pública de Bogotá over a 12 month period.

MATERIALS AND METHODS

A total of 100 positive cultures for acid-fast bacilli from public and private hospitals from Bogotá were identified by both biochemical methods and the molecular methods PRA (PCR-restriction enzyme analysis) and multiplex-PCR. Furthermore, low prevalence mycobacteria species and non-interpretable results were confirmed by 16SrDNA sequentiation analysis.

RESULTS

Identification using the PRA method showed NMT occurrence in 11% of cultures. In addition, this molecular methodology allowed to detect the occurrence of more than one mycobacteria in 4% of the cultures. Interestingly, a new M. kubicae pattern of PCR-restriction analysis is reported in our study.

CONCLUSION

Using a mycobacteria identification algorithm, which includes the molecular method PRA, improves the diagnostic power of conventional methods and could help to advance both NTM epidemiology knowledge and mycobacteriosis control.

Management of nontuberculous mycobacterial infection in the elderly

The incidence of nontuberculous mycobacteria (NTM) has increased over the last decades. Elderly people are more susceptible to NTM and experience increased morbidities. NTM incidence is expected to rise due to an increasing elderly population at least up to 2050. Given the importance of NTM infection in the elderly, an increasing interest exists in studying NTM characteristics in the aged population. In this review, we summarize the characteristics of NTM infection among elderly patients. We focus on epidemiology, clinical presentation, and treatment options of NTM in this age group. We highlight the differences in the diagnosis and treatment between rapid and slow growing mycobacterial infections. The current recommendation for treatment of NTM is discussed. We debate if in vitro susceptibility testing has a role in the treatment of NTM. Drug-drug interaction between antibiotics used to treat NTM and other medications, particularly warfarin, is another important issue that we discuss. Finally, we review the prognosis of NTM disease in elderly patients.

Virulence and immune response induced by Mycobacterium avium complex strains in a model of progressive pulmonary tuberculosis and subcutaneous infection in BALB/c mice

The genus Mycobacterium comprises more than 150 species, including important pathogens for humans which cause major public health problems. The vast majority of efforts to understand the genus have been addressed in studies with Mycobacterium tuberculosis. The biological differentiation between M. tuberculosis and nontuberculous mycobacteria (NTM) is important because there are distinctions in the sources of infection, treatments, and the course of disease. Likewise, the importance of studying NTM is not only due to its clinical significance but also due to the mechanisms by which some species are pathogenic while others are not. Mycobacterium avium complex (MAC) is the most important group of NTM opportunistic pathogens, since it is the second largest medical complex in the genus after the M. tuberculosis complex. Here, we evaluated the virulence and immune response of M. avium subsp. avium and Mycobacterium colombiense, using experimental models of progressive pulmonary tuberculosis and subcutaneous infection in BALB/c mice. Mice infected intratracheally with a high dose of MAC strains showed high expression of tumor necrosis factor alpha (TNF-α) and inducible nitric oxide synthase with rapid bacillus elimination and numerous granulomas, but without lung consolidation during late infection in coexistence with high expression of anti-inflammatory cytokines. In contrast, subcutaneous infection showed high production of the proinflammatory cytokines TNF-α and gamma interferon with relatively low production of anti-inflammatory cytokines such as interleukin-10 (IL-10) or IL-4, which efficiently eliminate the bacilli but maintain extensive inflammation and fibrosis. Thus, MAC infection evokes different immune and inflammatory responses depending on the MAC species and affected tissue.

Community-based prevalence of undiagnosed mycobacterial diseases in the Afar Region, north-east Ethiopia

BACKGROUND

Information on the community-based prevalence of tuberculosis (TB) in different settings is vital for planning, execution and evaluation of strategies to control the disease.

OBJECTIVE

To assess community-based prevalence of undetected active pulmonary TB (PTB) in pastoralists of the Amibara District.

METHODS

Between March and April 2010, a community-based cross-sectional survey of undiagnosed active PTB was conducted in the pastoralists of the Amibara District of the Afar Region, north-east Ethiopia. The study participants were interviewed for symptoms suggestive of PTB using a structured questionnaire. Sputum samples were collected and processed for smear microscopy and culture. Mycobacterium genus typing was performed using a multiplex polymerase chain reaction (PCR).

RESULTS

Out of 222 individuals who had symptoms suggestive of PTB, 4 (1.8%) were found positive by smear microscopy, while mycobacterial growth was observed on 62 (27.9%) samples. Mycobacterium genus typing was carried out for 42 of these 62 samples; 39 (92.9%) gave a positive signal for the genus Mycobacterium. Of these, 23 (59%) isolates proved to be members of the Mycobacterium tuberculosis (Mtb) complex, while the remaining 16 (41.0%) were found to be members of non-tuberculous Mycobacteria (NTM) species.

CONCLUSION

Sputum culture is highly sensitive, and it is the gold standard for the bacteriological diagnosis of PTB, while smear microscopy is less sensitive to detect acid fast bacilli (AFB) in stained sputum smears. The findings of the present study warrant the strengthening of culture facility services in the study area. The study also provides important preliminary information on the status of NTM infection in the pastoral setting. Nevertheless, further investigations into the species identification of the NTM infections would be useful in the study area.

Rapid culture diagnosis of tuberculous lymphadenitis from a tertiary care centre in an endemic nation: potential and pitfalls

In spite of low sensitivity and specificity, standard diagnostic algorithm recommends fine needle aspiration cytology (FNAC) and direct microscopic screening for acid-fast bacilli (AFB) for the routine diagnosis of tuberculous lymphadenopathy (LNTB). In this study, the diagnostic utility of liquid broth based automated culture (BacT/ALERT 3D) technique was assessed in comparison with conventional techniques in 89 clinically suspected tubercular lymphadenitis patients. 60% (n = 53) were positive by FNAC and 38.4% (n = 34) demonstrated AFB in smear examination. BacT/ALERT yielded isolation in 43.1% (n = 38) aspirates, confirming tubercular aetiology. We also found six paediatric culture-positive cases which showed negative outcome by both FNAC and smear. Thus, we conclude that culture by BacT/ALERT, may be used for faster yield of Mycobacteria in LNTB, especially in children. Additionally, this could also be used as a platform for further differentiation of Mycobacterium tuberculosis from non-tuberculous mycobacteria (NTM) infection and for testing of anti-tubercular chemotherapeutic agents whenever drug resistance is suspected.

First insights into the genetic diversity of Mycobacterium tuberculosis isolates from HIV-infected Mexican patients and mutations causing multidrug resistance

BACKGROUND

The prevalence of infections with Mycobacterium tuberculosis (MTb) and nontuberculous mycobacteria (NTM) species in HIV-infected patients in Mexico is unknown. The aims of this study were to determine the frequency of MTb and NTM species in HIV-infected patients from Mexico City, to evaluate the genotypic diversity of the Mycobacterium tuberculosis complex strains, to determine their drug resistance profiles by colorimetric microplate Alamar Blue assay (MABA), and finally, to detect mutations present in katG, rpoB and inhA genes, resulting in isoniazid (INH) and rifampin (RIF) resistance.

RESULTS

Of the 67 mycobacterial strains isolated, 48 were identified as MTb, 9 as M. bovis, 9 as M. avium and 1 as M. intracellulare. IS6110-RFLP of 48 MTb strains showed 27 profiles. Spoligotyping of the 48 MTb strains yielded 21 patterns, and 9 M. bovis strains produced 7 patterns. Eleven new spoligotypes patterns were found. A total of 40 patterns were produced from the 48 MTb strains when MIRU-VNTR was performed. Nineteen (39.6%) MTb strains were resistant to one or more drugs. One (2.1%) multidrug-resistant (MDR) strain was identified. A novel mutation was identified in a RIF-resistant strain, GAG --> TCG (Glu --> Ser) at codon 469 of rpoB gene.

CONCLUSIONS

This is the first molecular analysis of mycobacteria isolated from HIV-infected patients in Mexico, which describe the prevalence of different mycobacterial species in this population. A high genetic diversity of MTb strains was identified. New spoligotypes and MIRU-VNTR patterns as well as a novel mutation associated to RIF-resistance were found. This information will facilitate the tracking of different mycobacterial species in HIV-infected individuals, and monitoring the spread of these microorganisms, leading to more appropriate measures for tuberculosis control.

Yield of HIV-associated tuberculosis during intensified case finding in resource-limited settings: a systematic review and meta-analysis

Intensified case finding is the regular screening for evidence of tuberculosis in people infected with HIV, at high risk of HIV, or living in congregate settings. We systematically reviewed studies of intensified case finding published between January, 1994, and April, 2009. In 78 eligible studies, the number of people with tuberculosis detected during intensified case finding varied substantially between countries and target groups of patients. Median prevalence of newly diagnosed tuberculosis was 0.7% in population-based surveys, 2.2% in contact-tracing studies, 2.3% in mines, 2.3% in programmes preventing mother-to-child transmission of HIV, 2.5% in prisons, 8.2% in medical and antiretroviral treatment clinics, and 8.5% in voluntary counselling and testing services. Metaregression analysis of studies that included only people with HIV showed that for each increment in national prevalence of tuberculosis of 100 cases per 100 000 population, intensified case finding identified an additional one case per 100 screened individuals (p=0.03). Microbiological sputum examination of all individuals without prior selection by symptom screening yielded an additional four cases per 100 individuals screened (p=0.05). Data on the use of serial screening, treatment outcomes in actively identified cases of tuberculosis, and cost-effectiveness, however, were lacking. Concerted action is needed to develop intensified case finding as an important method for control of tuberculosis.

Multiplex PCR assay for simultaneous detection and differentiation of Mycobacterium tuberculosis, Mycobacterium avium complexes and other Mycobacterial species directly from clinical specimens

AIMS

Polymerase chain reaction (PCR) is the most rapid and sensitive method for diagnosing mycobacterial infections and identifying the aetiological Mycobacterial species in order to administer the appropriate therapy and for better patient management.

METHODS AND RESULTS

Two hundred and thirty-five samples from 145 clinically suspected cases of tuberculosis were processed for the detection of Mycobacterial infections by ZN (Ziehl Neelsen) smear examination, L-J & BACTEC MGIT-960 culture and multiplex PCR tests. The multiplex PCR comprised of genus-specific primers targeting hsp65 gene, Mycobacterium tuberculosis complex-specific primer targeting cfp10 (Rv3875, esxB) region and Mycobacterium avium complex-specific primer pairs targeting 16S-23S Internal Transcribed Spacer sequences. The multiplex PCR developed had an analytical sensitivity of 10 fg (3-4 cells) of mycobacterial DNA. The multiplex PCR test showed the highest (77.24%) detection rate, while ZN smear examination had the lowest (20%) detection rate, which was bettered by L-J culture (34.4%) and BACTEC MGIT-960 culture (50.34%) methods. The mean isolation time for M. tuberculosis was 19.03 days in L-J culture and 8.7 days in BACTEC MGIT-960 culture. Using the multiplex PCR, we could establish M. tuberculosis + M. avium co-infection in 1.3% HIV-negative and 2.9% HIV-positive patients. The multiplex PCR was also highly useful in diagnosing mycobacteraemia in 38.09% HIV-positive and 15.38% HIV-negative cases.

CONCLUSIONS

The developed in-house multiplex PCR could identify and differentiate the M. tuberculosis and M. avium complexes from other Mycobacterial species directly from clinical specimens.

SIGNIFICANCE AND IMPACT OF THE STUDY

The triplex PCR developed by us could be used to detect and differentiate M. tuberculosis, M. avium and other mycobacteria in a single reaction tube.

Prevalence and predictors of tuberculosis coinfection among HIV-seropositive patients attending the Aminu Kano Teaching Hospital, northern Nigeria

BACKGROUND

The HIV/AIDS epidemic has been accompanied by a severe epidemic of tuberculosis (TB), although the prevalence of coinfection is largely unknown, especially in developing countries, including Nigeria. The aim of this study was to determine the prevalence and predictors of TB coinfection among HIV-seropositive Nigerians.

METHODS

The case files of HIV/AIDS patients attending Aminu Kano Teaching Hospital, Nigeria from January to December 2006 were reviewed.

RESULTS

A total of 1320 HIV/AIDS patients had complete records and were reviewed, among which 138 (10.5%) were coinfected with TB (95% CI, 8.9% to 12.2%). Pulmonary TB was diagnosed in 103 (74.6%) patients, among whom only 18 (17.5%) were sputum-positive. Fifty (36.2%) coinfected patients had some type of extrapulmonary TB (EPTB); 15 had both pulmonary TB and EPTB. Among the 35 patients with EPTB only, 20 (57.1%) had abdominal TB, 5 (14.3%) had TB adenitis, 5 (14.3%) had spinal TB, 3 (8.6%) were being monitored for tuberculous meningitis, and 1 (2.9%) each had renal TB and tuberculous adrenalitis. The highest prevalence of TB, 13.7% (n = 28), was seen among patients aged 41-50 years. TB coinfection was significantly associated with marital status, WHO clinical stage, and CD4 count. Marital status (OR, 2.1; 95% CI, 1.28-3.59; P = 0.04), WHO clinical stage at presentation (4.81; 1.42-8.34; P = 0.001), and baseline CD4 count (2.71; 1.51-6.21; P = 0.02) remained significant predictors after adjustment for confounding.

CONCLUSIONS

The moderately high prevalence of TB among HIV-seropositive patients underscores the urgent need for strategies that lead to rapid identification and treatment of coinfection with active or latent TB.

Isolamento de micobactérias não-tuberculosas em São José do Rio Preto entre 1996 e 2005

OBJETIVO: Estudar a ocorrência de micobactérias não-tuberculosas e a variabilidade das espécies isoladas na região atendida pelo Instituto Adolfo Lutz-Regional de São José do Rio Preto-no período entre 1996 e 2005, assim como mostrar a importância do diagnóstico laboratorial. MÉTODOS: A partir de amostras pulmonares e extrapulmonares, foi realizado o isolamento de micobactérias, e estas foram identificadas por métodos fenotípicos e pelo método molecular polymerase chain reaction-restriction enzyme analysis. RESULTADOS: Foram isoladas 317 cepas de micobactérias não-tuberculosas: complexo Mycobacterium avium, 182 (57,4%); M. gordonae, 33 (10,4%); M. fortuitum, 25(7,9%); M. chelonae, 8 (2,5%); complexo M. terrae, 8 (2,5%); M. kansasii, 7 (2,2%); e espécies menos freqüentes, 54 (17%). No período, foram caracterizados 72 casos (33,3%) de micobacterioses, de acordo com os critérios bacteriológicos estabelecidos pela American Thoracic Society (2007).Desses, complexo M. avium foi responsável por 56 casos, sendo que 29 (51,8%) foram caracterizados como doença disseminada. M. fortuitum foi responsável por 6 casos; M. gordonae, 3; M. chelonae, 2; M. abscessus, 1; M. kansasii, 1; M. intracellulare, 1; M. malmoense, 1; e Mycobacterium ssp., 1. CONCLUSÕES: Os resultados obtidos mostraram a importância do diagnóstico bacteriológico das micobacterioses, pois a identificação das espécies possibilita a introdução de um tratamento adequado precocemente.

Sputum microscopy for the diagnosis of HIV-associated pulmonary tuberculosis in Tanzania

Background

In many resource poor settings only sputum microscopy is employed for the diagnosis of HIV-associated pulmonary tuberculosis; sputum culture may not be available.

Methods

We determined the diagnostic accuracy of sputum microscopy for active case finding of HIV-associated pulmonary tuberculosis using TB culture as the reference standard.

Results

2216 potential subjects screened for a TB vaccine trial submitted 9454 expectorated sputum specimens: 212 (2.2%) were sputum culture positive for Mycobacterium tuberculosis (MTB), 31 (0.3%) for non-tuberculous mycobacteria, and 79 (0.8%) were contaminated. The overall sensitivity of sputum microscopy was 61.8% (131/212) and specificity 99.7% (9108/9132). Sputum microscopy sensitivity varied from 22.6% in specimens with < 20 colony forming units (CFU)/specimen to 94.2% in patients with > 100 CFU/specimen plus confluent growth. The incremental diagnostic value for sputum microscopy was 92.1%, 1.8% and 7.1% for the first, second and third specimens, respectively. The positive predictive value and negative predictive values for sputum microscopy were 84.5% and 99.1%, respectively. The likelihood ratio (LR) of a positive sputum microscopy was 235.1 (95% CI 155.8 – 354.8), while the LR of a negative test was 0.38 (95CI 0.32 – 0.45). The 212 positive sputum cultures for MTB represented 103 patients; sputum microscopy was positive for 57 (55.3%) of 103 patients.

Conclusion

Sputum microscopy on 3 expectorated sputum specimens will only detect 55% of culture positive HIV-infected patients in active screening for pulmonary tuberculosis. Sensitivity is higher in patients with greater numbers of CFUs in the sputum. Culture is required for active case finding of HIV- associated pulmonary tuberculosis.

Mycobacteria causing human cervical lymphadenitis in pastoral communities in the Karamoja region of Uganda

Mycobacteria from lymph node biopsies of patients with cervical lymphadenitis reporting for tuberculosis treatment in Matany and Moroto Hospitals in the transhumant areas of Karamoja, Uganda were isolated and characterized. The AccuProbe culture identification kits for Mycobacterium tuberculosis complex (MTC), M. avium complex (MAC) and M. avium were used to identify the isolates. Spoligotyping, IS901 PCR and IS1311 and IS1245 restriction fragment length polymorphism (RFLP) were used to characterize the isolates. Of the 43 biopsies, ten M. avium, seven M. tuberculosis, three M. bovis, and two M. intracellulare were isolated. Two isolates could not be identified with AccuProbe and from 19 samples no mycobacteria could be isolated. Three isolates with the Beijing spoligotype were identified from the seven M. tuberculosis isolates. The spoligopatterns of the M. bovis isolates had previously been detected in cattle in Uganda. Isolation of members of the MAC group reflects the complex interaction between the transhumant communities, water sources and their cattle. None of the M. avium isolates harboured IS901, and all showed several bands on IS1311 and IS1245 RFLP, in accordance with M. avium subsp. hominissuis. Composite dendrograms of IS1311 and IS1245 RFLP showed that the isolates were similar and identical patterns were found. The isolation of M. bovis confirms the human infection with zoonotic mycobacteria in areas where consumption of raw milk and meat is routine. Isolation of environmental mycobacteria also confirms their increasing role in human disease and the occupational risk of infection in the transhumant ecosystem in the absence of safe drinking water and environmental contamination.

Molecular features of Mycobacterium avium human isolates carrying a single copy of IS1245 and IS1311 per genome

Human clinical isolates of the Mycobacterium avium complex, from hospitals in Bogotá, were studied using a wide range of molecular tests including PCR restriction-enzyme analysis (PRA) of the hsp65 gene. Up to 21 of the isolates were identified as M. avium PRA variant III (Mav III), a variant obtained only from isolates on the American continent. In contrast to previous reports, restriction fragment length polymorphism analysis using IS1245 and IS1311 showed a single copy for each insertion sequence (IS) in the majority (19/21) of the Colombian Mav III isolates under study. In order to analyse whether the ISs were inserted in a relevant genomic region, experimental conditions were established to determine the insertion loci of each single copy of both ISs in the genome. Analysis of genomic insertion loci indicated that both IS1245 and IS1311 were present in areas containing putatively truncated integrases and/or transposases, which may have an influence on the mobility of the inserted IS. In addition, a conserved genomic region was identified for the insertion of IS1311; this region could be part of the IS1311 itself.

Improved recovery of Mycobacterium tuberculosis from children using the microscopic observation drug susceptibility method

OBJECTIVE

The diagnosis of pulmonary tuberculosis presents challenges in children, because symptoms are nonspecific, sputa are not accessible, and Mycobacterium tuberculosis cultures and smears often are negative. The Microscopic Observation Drug Susceptibility technique is a simple, inexpensive method for Mycobacterium tuberculosis isolation with superior speed and sensitivity over Lowenstein-Jensen culture in studies of adults with pulmonary tuberculosis. The objective of this study was to determine whether Microscopic Observation Drug Susceptibility culture can improve the sensitivity and the speed of Mycobacterium tuberculosis recovery among Peruvian children with symptoms suggestive of pulmonary tuberculosis.

METHODS

Two specimens of each type (gastric aspirate, nasopharyngeal aspirate, and stool specimens) were collected from each patient, examined by auramine stain, and cultured by Microscopic Observation Drug Susceptibility and Lowenstein-Jensen techniques. Patients (n = 165) were enrolled between April 2002 and February 2004 at the Instituto de Salud del Niño, the major pediatric hospital in Lima, Peru. Inclusion criteria were age < or = 12 years, Stegen-Toledo clinical score > or = 5 points, and absence of antituberculous therapy. The main outcome measurements were (1) proportion of specimens that were culture positive by Microscopic Observation Drug Susceptibility versus Lowenstein-Jensen and (2) days required for positive culture result, stratified by specimen type and auramine stain result.

RESULTS

Fifteen (9%) patients had at least 1 positive Mycobacterium tuberculosis culture (from stool in 3 cases, nasopharyngeal aspirate in 8 cases, and gastric aspirate in 15 cases). Thirty-eight culture-positive specimens were obtained (22 gastric aspirate, 12 nasopharyngeal aspirates, and 4 stools). Microscopic Observation Drug Susceptibility provided significantly more positive cultures than Lowenstein-Jensen (33 of 38 specimens culture positive by Microscopic Observation Drug Susceptibility vs 21 of 38 by Lowenstein-Jensen). This was attributed to enhanced recovery of Mycobacterium tuberculosis from auramine-negative specimens (19 of 23 by Microscopic Observation Drug Susceptibility vs 9 of 23 by Lowenstein-Jensen), in contrast to similar detection rates for the 2 tests with auramine-positive samples. Similar results were found for analyses that were limited to gastric aspirates. Isolation was faster by Microscopic Observation Drug Susceptibility than Lowenstein-Jensen.

CONCLUSIONS

Isolation of Mycobacterium tuberculosis from children with suspected pulmonary tuberculosis by Microscopic Observation Drug Susceptibility demonstrated greater yield and faster recovery than by Lowenstein-Jensen method, significantly improving local capabilities to detect pediatric tuberculosis in resource-poor settings.

Clinical correlates of tuberculosis co-infection in HIV-infected children hospitalized in Peru

INTRODUCTION

In developing countries, tuberculosis (TB) is responsible for almost 250,000 deaths among children yearly. Active TB in children with human immunodeficiency virus (HIV) infection is difficult to diagnose and progresses rapidly to death. The aim of this preliminary study was to investigate the prevalence and clinical correlates of TB-related illness among HIV-infected children admitted to an infectious diseases ward in Peru, a country where TB is highly endemic.

METHOD

Forty-seven HIV-infected children admitted for a suspected infectious process in a Peruvian hospital were investigated for evidence of clinical tuberculosis by auramine stain, culture, and polymerase chain reaction (PCR) of clinical specimens.

RESULTS

Eight children (17%) had evidence of tuberculosis, including five with positive cultures and three with positive PCR tests only. Weight loss was the only feature associated with a positive test for tuberculosis. Radiological changes were very common in both TB-positive and TB-negative groups and these changes were not useful to identify TB-positive cases.

CONCLUSIONS

Weight loss may be used to identify high-risk HIV positive children who require more aggressive evaluation for tuberculosis. Radiological changes were common in both TB-positive and TB-negative groups.

Non-tuberculous mycobacteria disease as a cause of hospitalization in HIV-infected subjects

OBJECTIVES

The present study characterized and determined the prevalence of mycobacterial diseases (tuberculosis (TB) and non-tuberculous mycobacteria (NTM)) as a cause of hospitalization among HIV-infected subjects consecutively admitted to a large metropolitan hospital during 2001/2002.

METHODS

Hospital discharge diagnoses were established for 521 HIV-positive patients.

RESULTS

Respiratory disease accounted for 49% of the admissions. Community acquired pneumonia (CAP) was the main cause of respiratory disease (52%) followed by Pneumocystis carinii (PCP, 24%), non-tuberculous mycobacteria (NTM, 11%) and Mycobacterium tuberculosis (TB, 9%). Mycobacterium tuberculosis disease was established using bacteriological, clinical and radiographic criteria. NTM disease was defined following the American Thoracic Society criteria. NTM was disseminated in the majority of cases (19 Mycobacterium avium complex (MAC), one Mycobacterium kansasii). Nine patients had respiratory disease (seven MAC, one Mycobacterium fortuitum, one Mycobacterium kansasii) and one had gastrointestinal disease caused by MAC. Mortality was 10% for NTM disseminated cases; none of the TB patients died over the course of the study. The length of hospitalization for NTM patients was longer (15+/-13 days) than for other respiratory cases (10+/-10, p=0.04).

CONCLUSIONS

NTM disease along with its related mortality is a significant pathology as a cause of hospitalization among HIV-infected individuals.

Non-tuberculous mycobacteria I: one year clinical isolates identification in Tertiary Hospital Aids Reference Center, Rio de Janeiro, Brazil, in pre highly active antiretroviral therapy era

The aim of this study was to determine the prevalence of non-tuberculous mycobacteria (NTM) isolates at University Hospital, Reference Center for Aids in Rio de Janeiro, Brazil, during one year. We used standard biochemical tests for species identification and IS1245 PCR amplification was applied as a Mycobacterium avium specific identification marker. Four hundred and four specimens from 233 patients yielded acid-fast bacilli growth. M. tuberculosis was identified in 85% of the patients and NTM in 15%. NTM disseminated infection was a common event correlated with human immunodeficiency virus (HIV) infected patients and only in HIV negative patients the source of NTM was non sterile site. M. avium complex (MAC) was biochemically identified in 57.8% (49/83) of NTM isolates, most of them from sterile sites (75.5%), and in 94% (46/49) the IS 1245 marker specific for M. avium was present. Twenty NTM strains showed a MAC biochemical pattern with the exception of a urease-positive (99% of MAC are urease-negative), however IS1245 was detected in 96% of the strains leading to their identification as M. avium. In this group differences in NTM source was not significant. The second most frequently isolated NTM was identified as M. scrofulaceum (7.2%), followed by M. terrae (3.6%), M. gordonae (2.4%), M. chelonae (1.2%), M. fortuitum (1.2%) and one strain which could not be identified. All were IS1245 negative except for one strain identified as M. scrofulaceum. It is interesting to note that non-sterile sites were the major source of these isolates (92.8%). Our finding indicated that M. avium is still the major atypical species among in the MAC isolates recovered from Brazilian Aids patients without highty active antiretroviral therapy schema. Some discrepancies were seen between the identification methods and further investigations must be done to better characterize NTM isolates using other phenotypic and genotypic methods.