Diagnosis of latent Mycobacterium tuberculosis infection: tuberculin test versus interferon-gamma release

Abstract: INTRODUCTION: The treatment of individuals with active tuberculosis (TB) and the identification and treatment of latent tuberculosis infection (LTBI) contacts are the two most important strategies for the control of TB. The objective of this study was compare the performance of tuberculin skin testing (TST) with QuantiFERON-TB Gold In TUBE(r) in the diagnosis of LTBI in contacts of patients with active TB. METHODS: Cross-sectional analytical study with 60 contacts of patients with active pulmonary TB. A blood sample of each contact was taken for interferon-gamma release assay (IGRA) and subsequently performed the TST. A receiver operating characteristic curve was generated to assess the cutoff points and the sensitivity, predictive values, and accuracy were calculated. The agreement between IGRA and TST results was evaluated by Kappa coefficient. RESULTS: Here, 67.9% sensitivity, 84.4% specificity, 79.1% PPV, 75% NPV, and 76.7% accuracy were observed for the 5mm cutoff point. The prevalence of LTBI determined by TST and IGRA was 40% and 46.7%, respectively. CONCLUSIONS: Both QuantiFERON-TB Gold In TUBE(r) and TST showed good performance in LTBI diagnosis. The creation of specific diagnostic methods is necessary for the diagnosis of LTBI with higher sensitivity and specificity, preferably with low cost and not require a return visit for reading because with early treatment of latent forms can prevent active TB.

Single-tube nested PCR assay with in-house DNA extraction for Mycobacterium tuberculosis detection in blood and urine

Abstract: INTRODUCTION : Molecular analyses are auxiliary tools for detecting Koch's bacilli in clinical specimens from patients with suspected tuberculosis (TB). However, there are still no efficient diagnostic tests that combine high sensitivity and specificity and yield rapid results in the detection of TB. This study evaluated single-tube nested polymerase chain reaction (STNPCR) as a molecular diagnostic test with low risk of cross contamination for detecting Mycobacterium tuberculosis in clinical samples. METHODS: Mycobacterium tuberculosis deoxyribonucleic acid (DNA) was detected in blood and urine samples by STNPCR followed by agarose gel electrophoresis. In this system, reaction tubes were not opened between the two stages of PCR (simple and nested). RESULTS: STNPCR demonstrated good accuracy in clinical samples with no cross contamination between microtubes. Sensitivity in blood and urine, analyzed in parallel, was 35%-62% for pulmonary and 41%-72% for extrapulmonary TB. The specificity of STNPCR was 100% in most analyses, depending on the type of clinical sample (blood or urine) and clinical form of disease (pulmonary or extrapulmonary). CONCLUSIONS: STNPCR was effective in detecting TB, especially the extrapulmonary form for which sensitivity was higher, and had the advantage of less invasive sample collection from patients for whom a spontaneous sputum sample was unavailable. With low risk of cross contamination, the STNPCR can be used as an adjunct to conventional methods for diagnosing TB.

Temporal distribution of tuberculosis in the State of Amazonas, Brazil

Tuberculosis (TB) is one of the infectious diseases that contributes most to the morbidity and mortality of millions of people worldwide. Brazil is one of 22 countries that accounts for 80% of the tuberculosis global burden. The highest incidence rates in Brazil occur in the States of Amazonas and Rio de Janeiro. The aim of this study was to describe the temporal distribution of TB in the State of Amazonas. Between 2001 and 2011, 28,198 cases of tuberculosis were reported in Amazonas, distributed among 62 municipalities, with the capital Manaus reporting the highest (68.7%) concentration of cases. Tuberculosis was more prevalent among males (59.3%) aged 15 to 34 years old (45.5%), whose race/color was predominantly pardo (64.7%) and who had pulmonary TB (84.3%). During this period, 81 cases of multidrug-resistant TB were registered, of which the highest concentration was reported from 2008 onward (p = 0.002). The municipalities with the largest numbers of indigenous individuals affected were São Gabriel da Cachoeira (93%), Itamarati (78.1%), and Santa Isabel do Rio Negro (70.1%). The future outlook for this region includes strengthening the TB control at the primary care level, by expanding diagnostic capabilities, access to treatment, research projects developed in collaboration with the Dr. Heitor Vieira Dourado Tropical Medicine Foundation .;Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD).; and financing institutions, such as the project for the expansion of the Clinical Research Center and the creation of a hospital ward for individuals with transmissible respiratory diseases, including TB.

The BACTEC MGIT(tm) 320 system as a laboratory tool to diagnose tuberculosis in a Brazilian hospital with a high prevalence of HIV infection

Abstract: INTRODUCTION: The World Health Organization endorses the BACTEC Mycobacterial Growth Indicator Tube (MGIT)(tm) system as a rapid, sensitive, and specific method to diagnostic of tuberculosis. Here, we compared the performance of this system against Ogawa-Kudoh cultures and microscopy. METHODS: A total of 927 samples were obtained between December 2011 and December 2013 from 652 cases of suspected tuberculosis at the School Hospital of the Federal University of Rio Grande in Brazil. RESULTS: The MGIT system confirmed tuberculosis in more cases in less time. CONCLUSIONS: The MGIT system is an effective tool for early diagnosis of tuberculosis, especially in patients with HIV/AIDS.

Molecular characterization of Mycobacterium tuberculosis isolates from Tehran, Iran by restriction fragment length polymorphism analysis and spoligotyping

Abstract: INTRODUCTION Characterization of Mycobacterium tuberculosis (MTB) isolates by DNA fingerprinting has contributed to tuberculosis (TB) control. The aim of this study was to determine the genetic diversity of MTB isolates from Tehran province in Iran. METHODS MTB isolates from 60 Iranian and 10 Afghan TB patients were fingerprinted by standard IS6110-restriction fragment length polymorphism (RFLP) analysis and spoligotyping. RESULTS The copy number of IS6110 ranged from 10-24 per isolate. The isolates were classified into 22 clusters showing ≥ 80% similarity by RFLP analysis. Fourteen multidrug-resistant (MDR) isolates were grouped into 4 IS6110-RFLP clusters, with 10 isolates [71% (95% CI: 45-89%)] in 1 cluster, suggesting a possible epidemiological linkage. Eighteen Iranian isolates showed ≥ 80% similarity with Afghan isolates. There were no strains with identical fingerprints. Spoligotyping of 70 isolates produced 23 distinct patterns. Sixty (85.7%) isolates were grouped into 13 clusters, while the remaining 10 isolates (14.2%) were not clustered. Ural (formerly Haarlem4) (n = 22, 31.4%) was the most common family followed by Central Asian strain (CAS) (n = 18, 25.7%) and T (n = 9, 12.8%) families. Only 1strain was characterized as having the Beijing genotype. Among 60 Iranian and 10 Afghan MTB isolates, 25% (95% CI: 16-37) and 70% (95% CI: 39-89) were categorized as Ural lineage, respectively. CONCLUSIONS A higher prevalence of Ural family MTB isolates among Afghan patients than among Iranian patients suggests the possible transmission of this lineage following the immigration of Afghans to Iran.

Two decades of tuberculosis in a city in Northeastern Brazil: advances and challenges in time and space

Abstract: INTRODUCTION This study presents two decades of epidemiological data on tuberculosis (TB), in order to understanding the disease profile and its spatiotemporal dynamics. METHODS This descriptive study was performed in the City of Olinda/Pernambuco, Brazil, from 1991-2010, and it analyzed new patients with TB living in the city. We used the χ²-test with a p-value <0.05 to identify differences in trends. Incidence and cluster distribution were identified using spatial scan statistics. RESULTS In total, 6202 new cases were recorded during the two decades. The highest incidence occurred in 1995 (110 cases/100,000 inhabitants), and the lowest occurred in 2009 (65 cases/100,000 inhabitants) (β=-1.44; R²=0.43; p=0.0018). The highest mortality occurred in 1998 (16 deaths/100,000 inhabitants), and the lowest occurred in 2008 (5 deaths/100,000 inhabitants) (β=-0.19; R²=0.17; p=0.07). There was a male predominance (65%), and ages ranged from 20-49 years (65%). There was a substantial increase in the number of patients that were cured after treatment (60% to 67%; p<0.001) as well as those tested for HIV (1.9% to 58.5%; p<0.001). During the first decade, clusters with p-values <0.05 included 29% of the total notified cases, and in the second decade, that percentage was 12%. CONCLUSIONS We observed a decreasing trend in incidence, which was significant, and mortality rates, which was not significant. The increased number of laboratory tests performed reflects advances in surveillance, and a reduction in the proportion of cases in primary clusters suggests, among other things, that the disease is spreading across the region.

Clinical and epidemiological features of AIDS/tuberculosis comorbidity

Considering the relevance of AIDS/tuberculosis comorbidity worldwide, especially in Brazil, this study was developed to describe the clinical and epidemiological features of the comorbid cases identified from 1989 to 1997 by the epidemiology service of the Hospital das Clínicas of the Universidade de São Paulo. METHODS: Databases containing information on all identified AIDS/tuberculosis cases cared for at the hospital were used to gather information on comorbid cases. RESULTS: During the period, 559 patients were identified as presenting with AIDS/tuberculosis comorbidity. Risk behavior for AIDS was primarily heterosexual contact (38.9%), followed by intravenous drug use (29.3%) and homosexual/bisexual contact (23.2%). Regarding clinical features, there were higher rates of extrapulmonary tuberculosis when compared to tuberculosis without comorbidity. There was an increase in reporting of AIDS by ambulatory units during the period. Epidemiologically, there was a decrease in the male/female ratio, a predominance in the 20 to 39 year-old age group, and a majority of individuals who had less than 8 years of schooling and had low professional qualifications. CONCLUSIONS: High rates of AIDS/tuberculosis cases at our hospital indicate the need for better attention towards early detection of tuberculosis, especially in its extrapulmonary form. Since the population that attends this hospital tends to be of a lower socioeconomic status, better management of AIDS and tuberculosis is required to increase the rates of treatment adherence and thus lower the social costs.

Bile duct-duodenal fistula caused by AIDS/HIV-associated tuberculosis

Allthough infrequent, digestive fistulae in HIV/AIDS patients have been reported throughout the digestive tract from the esophagus to the anus, with predominance of esophageal fistulae. AIDS/HIV-associated opportunistic infections may invade the digestive system and lead to fistula formation. Tuberculosis is the most common infection associated with these esophageal fistulae. We report here one case of bile duct-duodenal fistula in a female AIDS patient with associated abdominal Mycobacterium tuberculosis infection compromising lymphnodes of the hepatic pedicle where the fistula was found. According to the reviewed literature, this is the third case of bile duct-duodenal fistula associated with abdominal tuberculosis in AIDS patient, and the first where both the fistula and the tuberculosis infection were diagnosed at laparotomy for acute abdomen. Whether the AIDS patient with abdominal pain needs or not a laparotomy to treat an infectious disease is often a difficult matter for the surgeon to decide, as most of the times appropriate medical treatment will bring more benefit.

New method for evaluation of cutaneous sensibility in diabetic feet: preliminary report

Diabetic neuropathy is an important complication of the disease, responsible for ulceration and amputation of the foot. Prevention of these problems is difficult mainly because there is no method to correctly access sensibility on the skin of the foot. The introduction of the Pressure-Specified Sensory Device (PSSD TM) in the last decade made possible the measurement of pressure thresholds sensed by the patient, such as touch, both static and in movement, on a continuous scale. This paper is the first in Brazil to report the use of this device to measure cutaneous sensibility in 3 areas of the foot: the hallux pulp, the calcaneus, and the dorsum, which are territories of the tibial and fibular nerves. METHOD: Non-diabetic patients were measured as controls, and 2 groups of diabetic patients - with and without ulcers - were compared. The PSSD TM was used to test the 3 areas described above. The following were evaluated: 1 PS (1-point static), 1 PD (1-point dynamic), 2 PS (2-points static), 2 PD (2-points dynamic). RESULTS: The diabetic group had poorer sensibility compared to controls and diabetics with ulcers had poorer sensibility when compared to diabetics without ulcers. The differences were statistically significant (P <.001). CONCLUSION: Due to the small number of patients compared, the results should be taken as a preliminary report.

LAY USE OF AMAZONIAN PLANTS FOR THE TREATMENT OF TUBERCULOSIS

The Brazilian State of Amazonas has a high incidence of Tuberculosis, 91.4 in 10,000 habitants (SESAU, 1994) and resistant strains of Mycobacterium tuberculosis are frequently being found in the region (SALEM et.al, 1990). These problems have been associated with side effects caused by the antibiotics used to treat Tuberculosis, which have in rum been associated with treatment non-compliance (PATTISAPU, 1984). To resolve this problem a cost effective alternative treatment for Tuberculosis with few or no side effects, needs to be found. Amazonas has an abundance of plants, many of which are used by the lay population for medicinal purposes. A survey was carried out in five towns of the region, interviewing patients receiving treatment for Tuberculosis, to find out whether and which plants have been used to treat Tuberculosis. Results showed that the majority of patients in the sample had used medicinal plants before or after diagnosis of Tuberculoses. Thirteen different plants were recorded for this purpose. Chenopodium ambrosioides L, popularly known as Mastruz, was the most commonly used, followed by Caesalpinia ferrea Mart. Jucá and Spilanthes acmella DC. Jambu. This study concentrates on Mastruz as it was used more frequently than the other medicinal plants. No significant effects on baciloscopy test results were found when Mastruz was used before diagnosis. ln-vitro laboratory tests have also not shown any tuberculocidal effects for Mastruz. Further tests are being carried out on the other medicinal plants.

Cutaneous allergic reactions to Triatoma infestans after xenodiagnosis

We determined the frequency of cutaneous allergic reactions to bites of Triatoma infestans during xenodiagnosis in a rural community where Panstrongylus megistrus is the only domestic vector of Trypanosoma cruzi. Localized urticaria or more intense cutaneous allergic reactions at 48 and 72 hours were observed in 86.7% and 82.1% respectively of the individuals in our study. Urticaria was more severe in children and older adults and in women than in men. The high frequency of reactions suggests either cutaneous reactivity to T. infestans without prior sensitization or cross reactivity between P. megistus and T. infestans. A single application of topical corticosteroid or antihistamine medication did not reduce the cutaneous reactions.

The principal reservoir host of cutaneous leishmaniasis in the urban areas of Manaus, Central Amazon of Brazil

Twenty one opossums (Didelphis marsupialis) from disturbed primary forest in the vicinity of Manaus, and seven from an isolated island of secondary vegetation within the city of Manaus, were examined for the presence of Leishmania. Of the opossums from the primary forests, 13 (61.9%) were found to be positive for Leishmania braziliensis guyanenesis. One additional opossum was found to be positive for Le. mexicana amazonensis. A simple and economical trapping technique for opossums is presented here, and a control method in special cases is suggested.

Study of an outbreak of cutaneous leishmaniasis in Venezuela: the role of domestic animals

During an outbreak of cutaneous leishmaniasis in a locality (Las Rosas, Cojedes State, venezuela) previously non-endemic, 12.9% of humans, 7% of dogs and 21.4% of donkeys (Equus asinus) had lesions with paraites. The agent in the three hosts was identified as Leishmania braziliensis, subspecies braziliensis at least in man and donkey. The probable vector was Lutzomyia panamensis. No infection was found in a small sample of wild mammals examined. The outbreak was apparently linked with the importation of donkeys with ulcers, from endemic areas. The Authors call attention to the fact that not only in the foci of "uta", but also in areas of the other forms of American cutaneous leishmaniasis, dogs are frequently found infected. They emphasize the necessity of searching for the infection in donkeys and of performing hemocultures and xenodiagnosis with sandflies in human, canine and equine cases, to verify their possible role as sources of infection, and not merely as dead ends in the epidemiological chain of the disease.

Experimental infection of Lutzomyia longipalpis fed on a patient with cutaneous leishmaniasis due to Leishmania mexicana amazonensis

The authors were able to infect phlebotomine sandflies on a human case of American Cutaneous Leishmaniasis by feeding females of Lutzomyia longipalpis on a patient with a lesion due to Leishmania mexicana amazonensis.