Detection of Mycobacterium tuberculosis DNA on the oral mucosa of tuberculosis patients.

Diagnosis of pulmonary tuberculosis (TB) usually includes laboratory analysis of sputum, a viscous material derived from deep in the airways of patients with active disease. As a diagnostic sample matrix, sputum can be difficult to collect and analyze by microbiological and molecular techniques. An alternative, less invasive sample matrix could greatly simplify TB diagnosis. We hypothesized that Mycobacterium tuberculosis cells or DNA accumulate on the oral epithelia of pulmonary TB patients, and can be collected and detected by using oral (buccal) swabs. To test this hypothesis, 3 swabs each were collected from 20 subjects with active pulmonary TB and from 20 healthy controls. Samples were tested by using a polymerase chain reaction (PCR) specific to the M. tuberculosis IS6110 insertion element. Eighteen out of 20 confirmed case subjects (90%) yielded at least 2 positive swabs. Healthy control samples were 100% negative. This case-control study supports past reports of M. tuberculosis DNA detection in oral swabs. Oral swab samples are non-invasive, non-viscous, and easy to collect with or without active TB symptoms. These characteristics may enable simpler and more active TB case finding strategies.

Pre-Columbian tuberculosis in Tierra del Fuego? Discussion of the paleopathological and molecular evidence.

This work contributes to ongoing discussions about the nature of tuberculosis in the Western Hemisphere prior to the time of European contact. Our example, from the extreme south of South America was, at the time of our study, without firm temporal association or molecular characterization. In Tierra del Fuego, Constantinescu (1999) briefly described vertebral bone lesions compatible with TB in an undated skeleton from Myren 1 site (Chile). The remains of Myren are estimated to represent a man between 18 and 23 years old at the time of death. The objectives of this research are to extend this description, to present molecular results, to establish a radiocarbon date, and to report stable isotopic values for the remains. We provide further description of the remains, including tuberculosis-like skeletal pathology. Radiocarbon dating of 640±20 years BP attributes this individual to the precontact fourteenth-fifteenth centuries. Isotopic ratios for nitrogen and carbon from bone collagen suggest a mixed diet. Molecular results were positive for the rpoB quantitative PCR (qPCR) assays but negative for two independent IS6110 and IS1081 qPCR assays. Further testing using genomic methods to target any mycobacteria for specific identification are needed.

Detection of Mycobacterium tuberculosis Complex in New World Monkeys in Peru.

The Mycobacterium tuberculosis complex causes tuberculosis in humans and nonhuman primates and is a global public health concern. Standard diagnostics rely upon host immune responses to detect infection in nonhuman primates and lack sensitivity and specificity across the spectrum of mycobacterial infection in these species. We have previously shown that the Oral Swab PCR (OSP) assay, a direct pathogen detection method, can identify the presence of M. tuberculosis complex in laboratory and free-ranging Old World monkeys. Addressing the current limitations in tuberculosis diagnostics in primates, including sample acquisition and pathogen detection, this paper furthers our understanding of the presence of the tuberculosis-causing bacteria among New World monkeys in close contact with humans. Here we use the minimally invasive OSP assay, which includes buccal swab collection followed by amplification of the IS6110 repetitive nucleic acid sequence specific to M. tuberculosis complex subspecies, to detect the bacteria in the mouths of Peruvian New World monkeys. A total of 220 buccal swabs from 16 species were obtained and positive amplification of the IS6110 sequence was observed in 30 (13.6%) of the samples. To our knowledge, this is the first documentation of M. tuberculosis complex DNA in a diverse sample of Peruvian Neotropical primates.

Pre-Columbian mycobacterial genomes reveal seals as a source of New World human tuberculosis.

Modern strains of Mycobacterium tuberculosis from the Americas are closely related to those from Europe, supporting the assumption that human tuberculosis was introduced post-contact. This notion, however, is incompatible with archaeological evidence of pre-contact tuberculosis in the New World. Comparative genomics of modern isolates suggests that M. tuberculosis attained its worldwide distribution following human dispersals out of Africa during the Pleistocene epoch, although this has yet to be confirmed with ancient calibration points. Here we present three 1,000-year-old mycobacterial genomes from Peruvian human skeletons, revealing that a member of the M. tuberculosis complex caused human disease before contact. The ancient strains are distinct from known human-adapted forms and are most closely related to those adapted to seals and sea lions. Two independent dating approaches suggest a most recent common ancestor for the M. tuberculosis complex less than 6,000 years ago, which supports a Holocene dispersal of the disease. Our results implicate sea mammals as having played a role in transmitting the disease to humans across the ocean.

From the mouths of monkeys: detection of Mycobacterium tuberculosis complex DNA from buccal swabs of synanthropic macaques.

Although the Mycobacterium tuberculosis complex (MTBC) infects a third of all humans, little is known regarding the prevalence of mycobacterial infection in nonhuman primates (NHP). For more than a century, tuberculosis has been regarded as a serious infectious threat to NHP species. Advances in the detection of MTBC open new possibilities for investigating the effects of this poorly understood pathogen in diverse populations of NHP. Here, we report results of a cross-sectional study using well-described molecular methods to detect a nucleic acid sequence (IS6110) unique to the MTBC. Sample collection was focused on the oral cavity, the presumed route of transmission of MTBC. Buccal swabs were collected from 263 macaques representing 11 species in four Asian countries and Gibraltar. Contexts of contact with humans included free ranging, pets, performing monkeys, zoos, and monkey temples. Following DNA isolation from buccal swabs, the polymerase chain reaction (PCR) amplified IS6110 from 84 (31.9%) of the macaques. In general, prevalence of MTBC DNA was higher among NHP in countries where the World Health Organization reports higher prevalence of humans infected with MTBC. This is the first demonstration of MTBC DNA in the mouths of macaques. Further research is needed to establish the significance of this finding at both the individual and population levels. PCR of buccal samples holds promise as a method to elucidate the mycobacterial landscape among NHP, particularly macaques that thrive in areas of high human MTBC prevalence.

Naturally acquired Mycobacterium tuberculosis complex in laboratory pig-tailed macaques.

Here we present a case series from a primate research facility. The index case, a 4-year-old pig-tailed macaque (Macaca nemestrina) experimentally infected with chimeric simian-human immunodeficiency virus (SHIVSF162 P4), developed weight loss and was euthanized. Based on necropsy results the animal was diagnosed with opportunistic atypical mycobacteriosis associated with simian AIDS (SAIDS). Subsequently, tissues from the index animal, as well as tissues and oral mucosal swabs from six SHIV-infected contacts, were analyzed using molecular methods and found to contain nucleic acid sequences characteristic of Mycobacterium tuberculosis complex (MTBC). These data suggest that existing protocols fail to reliably detect MTBC infection in laboratory primates used as experimental models.

Tuberculosis and leprosy in perspective.

Two of humankind's most socially and psychologically devastating diseases, tuberculosis and leprosy, have been the subject of intensive paleopathological research due to their antiquity, a presumed association with human settlement and subsistence patterns, and their propensity to leave characteristic lesions on skeletal and mummified remains. Despite a long history of medical research and the development of effective chemotherapy, these diseases remain global health threats even in the 21st century, and as such, their causative agents Mycobacterium tuberculosis and M. leprae, respectively, have recently been the subject of molecular genetics research. The new genome-level data for several mycobacterial species have informed extensive phylogenetic analyses that call into question previously accepted theories concerning the origins and antiquity of these diseases. Of special note is the fact that all new models are in broad agreement that human TB predated that in other animals, including cattle and other domesticates, and that this disease originated at least 35,000 years ago and probably closer to 2.6 million years ago. In this work, we review current phylogenetic and biogeographic models derived from molecular biology and explore their implications for the global development of TB and leprosy, past and present. In so doing, we also briefly review the skeletal evidence for TB and leprosy, explore the current status of these pathogens, critically consider current methods for identifying ancient mycobacterial DNA, and evaluate coevolutionary models.

Vitamin D receptor gene polymorphisms and susceptibility M. tuberculosis in native Paraguayans.

Tuberculosis (TB) is a significant health problem for most of the world's populations, and prevalence among indigenous groups is typically higher than among their nonindigenous neighbors. Native South Americans experience high rates of TB, but while research in several other world populations indicates that susceptibility is multifactorial, polygenic, and population-specific, little work has been undertaken to investigate factors involved in Native American susceptibility. We conducted a family-based association study to examine immunologically relevant polymorphisms of a candidate gene, the vitamin D receptor, in conjunction with three measures of TB status in two Native Paraguayan populations, the Aché and the Avá. This is the first large-scale genetic analysis of Native South Americans to examine susceptibility to both infection and disease following exposure to M. tuberculosis. These two types of susceptibility reflect differences in innate and acquired immunity that have proven difficult to elucidate in other populations. Our results indicate that among the Aché, the FokI F allele protects individuals from infection, while the TaqI t allele protects against active disease but not infection. In particular, FF homozygotes are 17 times more likely to test positive for exposure to TB, but no more likely to have ever been diagnosed with active TB. TT individuals are 42 times less likely to mount a delayed-type hypersensitivity response, and the T allele was significantly more likely to have been transmitted to offspring who have been diagnosed with active TB. This ongoing research is of vital importance to indigenous groups of the Americas, because if there is a population-specific component to TB susceptibility, it will likely prove most effective to incorporate this into future treatment and prevention strategies.

Patterns of tuberculosis in the Americas: how can modern biomedicine inform the ancient past?

Tuberculosis (TB) is an infectious disease that continues to take its toll on human lives. Paleopathological research indicates that it has been a significant cause of death among humans for at least five thousand years. Because of the devastating consequences to human health, social systems, and endangered primate species, TB has been the subject of many and varied research efforts throughout the world, efforts that are amassing an enormous amount of data concerning the causative agent Mycobacterium tuberculosis. Despite sequencing of the M. tuberculosis genome and numerous molecular epidemiological studies, many questions remain regarding the origin, evolution, and future co-evolutionary trajectory of M. tuberculosis and humans. Indeed, the origin of pre-Columbian New World TB has been and remains hotly debated, and resolution of this controversy will likely only come with integration of data and theory from multiple disciplines. In this paper, we discuss the pre-Columbian TB controversy, and then use research from biological and biomedical sciences to help inform paleopathological and archaeological studies of this ubiquitous disease that plagued our ancient forbears.

Patterns of tuberculosis in the Americas: how can modern biomedicine inform the ancient past?

Tuberculosis (TB) is an infectious disease that continues to take its toll on human lives. Paleopathological research indicates that it has been a significant cause of death among humans for at least five thousand years. Because of the devastating consequences to human health, social systems, and endangered primate species, TB has been the subject of many and varied research efforts throughout the world, efforts that are amassing an enormous amount of data concerning the causative agent Mycobacterium tuberculosis. Despite sequencing of the M. tuberculosis genome and numerous molecular epidemiological studies, many questions remain regarding the origin, evolution, and future co-evolutionary trajectory of M. tuberculosis and humans. Indeed, the origin of pre-Columbian New World TB has been and remains hotly debated, and resolution of this controversy will likely only come with integration of data and theory from multiple disciplines. In this paper, we discuss the pre-Columbian TB controversy, and then use research from biological and biomedical sciences to help inform paleopathological and archaeological studies of this ubiquitous disease that plagued our ancient forbears.