Mycobacterial species diversity at a general hospital on the island of Crete: First detection of Mycobacterium lentiflavum in Greece

Global Environmental Nontuberculous Mycobacteria and Their Contemporaneous Man-Made and Natural Niches

Seminal microbiological work of environmental nontuberculous mycobacteria (NTM) includes the discovery that NTM inhabit water distribution systems and soil, and that the species of NTM found are geographically diverse. It is likely that patients acquire their infections from repeated exposures to their environments, based on the well-accepted paradigm that water and soil bioaerosols - enriched for NTM - can be inhaled into the lungs. Support comes from reports demonstrating NTM isolated from the lungs of patients are genetically identical to NTM found in their environment. Well documented sources of NTM include peat-rich soils, natural waters, drinking water, hot water heaters, refrigerator taps, catheters, and environmental amoeba. However, NTM have also been recovered in biofilms from ice machines, heated nebulizers, and heater-cooler units, as well as seat dust from theaters, vacuum cleaners, and cobwebs. New studies on the horizon aim to significantly expand the current knowledge of environmental NTM niches in order to improve our current understanding of the specific ecological factors driving the emergence of NTM lung disease. Specifically, the Hawaiian Island environment is currently being studied as a model to identify other point sources of exposure as it is the U.S. state with the highest number of NTM lung disease cases. Because of its geographic isolation and unique ecosystem, the Hawaiian environment is being probed for correlative factors that may promote environmental NTM colonization.

Nontuberculous Mycobacteria in Saudi Arabia and Gulf Countries: A Review

Nontuberculous Mycobacteria (NTM) are causing growing health problems worldwide. This is indicated by an increasing amount of scientific reports showing not only well-identified species reemerging but also emergence of new species. The emergence and reemergence of NTM are particularly worrying in developing countries due to scarce published data and improper identification. Here we aimed to examine the main epidemiological aspects and diagnostic challenges associated with NTM in countries of the Gulf Cooperation Council (GCC) and compare these findings to the international arena findings. Data revealed that countries of the GCC are largely dominated by rapidly growing mycobacteria species such as M. fortuitum (29%) and M. abscessus (17%) with high rate of definitive respiratory diseases. On the other hand, most of the developed countries are dominated by slowly growing mycobacteria such as MAC, M. kansasii, and M. gordonae. More efforts are needed, however, to gain insights into NTM issues in countries of the GCC.

Mycobacterium heraklionense sp. nov.: A case series

Mycobacterium heraklionense sp. nov. (M. heraklionense) is a novel non-tuberculous mycobacterium belonging to the Mycobacterium terrae complex that has recently been described. It has a world-wide distribution. Recently, a case of tenosynovitis in an immunocompetent individual caused by M. heraklionense was reported, indicating that it has the ability to cause diseases. In the present study, in order to provide a more detailed profile of this mycobacterium and to obtain a more complete overall picture of its clinical significance, we report all available data regarding the initial 12 cases of its isolation. Of the 12 patients, 5 (42%) eventually died within a period of 3 months following the isolation of the mycobacterium. However, any connection between the presence of M. heraklionense and these deaths could not be documented. These 5 patients were all males with a mean age of 74.6 years suffering from serious underlying diseases, which most probably were the cause of death. Additional data from possible new cases of M. heraklionense isolation are anticipated.

Distribution of nontuberculous mycobacteria in treated patients with pulmonary disease in Greece – relation to microbiological data

Aims. The aim was to assess the distribution of nontuberculous mycobacteria (NTM) in treated patients with pulmonary disease (PD) in Greece. Patients & methods. Patients treated for NTM PD at the two largest chest diseases hospitals in Greece, in the period 1990–2013 were investigated. For the years 2005–2013 data on NTM isolation frequency were recorded. Results. M. avium complex (MAC) was the predominant cause of NTM PD disease followed by M. kansasii and rapid growing mycobacteria (RGM). The pathogenicity of RGM was significantly lower than this of MAC and M. kansasii. An increase was observed in the percentage of isolated NTM species that were considered clinically significant over the study period. Conclusions. The increasing number of NTM PD in Greece is a consequence of their isolation being more frequently considered as clinically relevant.

Comparison of Mycobacterium lentiflavum and Mycobacterium avium-intracellulare complex lymphadenitis

BACKGROUND

Mycobacterium lentiflavum is considered a rare pathogen causing nontuberculous mycobacterial (NTM) lymphadenitis.

METHODS

A multicenter, retrospective study was performed in immunocompetent children <14 years of age with microbiologically confirmed NTM lymphadenitis treated at 6 hospitals in Madrid, Spain, during 2000-2010. We compared children with M. lentiflavum and Mycobacterium avium-intracellulare complex infection.

RESULTS

Forty-five microbiologically confirmed NTM lymphadenitis patients were identified: 19 (45.2%) caused by M. avium-intracellulare complex, 17 (40.5%) by M. lentiflavum, 1 by both and 5 by other mycobacteria. Out of 17 M. lentiflavum cases, 14 were diagnosed in the past 5 years. Regarding M. lentiflavum cases, median age was 23 months. Submandibular nodes were the most frequently involved (76.5%), with multiple locations seen in 41% of the children and spontaneous drainage in 41% of them. Drug susceptibility tests were performed in 14 isolates and showed a complete susceptibility to clarithromycin and cycloserine, whereas 93% were resistant to rifampin, 33% to quinolones and full resistance to other tested antimycobacterial drugs was detected. All but 1 child required surgery and 11 were treated additionally with various drug combinations. Total resolution was achieved in 50% of children within 6 months.Compared with M. avium-intracellulare complex cases, children were younger and laterocervical nodes were significantly less frequently involved. No statistically significant differences were found related to clinical characteristics, treatment and outcome.

CONCLUSIONS

M. lentiflavum is an emerging pathogen producing NTM lymphadenitis in Madrid.

Emergence of clinically relevant Non-Tuberculous Mycobacterial infections in Saudi Arabia

Background

Non-Tuberculous Mycobacteria (NTM) are emerging around the world due to a higher prevalence of immunosuppressive illness and therapy. Saudi Arabia is not an exception as there have been novel mycobacterial species also identified. In addition, several published case reports from different parts of the country suggest a growing pathogenic potential of NTM. As the first nationwide study, we sought to gain an insight into the species diversity of NTM clinical isolates.

Methodology/Principal findings

During June 2009–July 2010, 95 clinical isolates were collected from tuberculosis reference laboratories in major provinces within Saudi Arabia and subjected to standard line probe assay techniques to identify their species. Diagnostic guidelines of the American Thoracic Society were applied to determine the clinical relevance of respiratory isolates.

Species diversity (13 species) was very high and dominated (61.0%) by rapid growing NTM. The major species obtained were Mycobacterium abscessus, M. fortuitum, M. intracellulare followed by M. kansassi, M. gordanae and M. avium. Interestingly this study reports for the first time the clinical relevance of M. celatum, M. xenopi, M. scrofulceum, M. lentiflavum, M. asiaticum and M. simiae in Saudi Arabia. Of the total, 67.1% were clinically relevant respiratory cases, 23.2% were non-respiratory cases and 9.7% were respiratory colonizers. Coexisting illness was reported in 53.7% of the studied cases. The major risk factors observed among the patients were previous history of tuberculosis, chronic obstructive pulmonary disorder and human immunodeficiency virus infection.

Conclusion/Significance

The high rates of clinically confirmed respiratory cases suggest that NTM infections are indeed a new challenge to health authorities. The current findings show an opposite picture of the Western world where M. avium complex and particularly slow growing NTM are the most predominant respiratory pathogens. The complexity of species demands an immediate strengthening of the current diagnostic facilities.

Non-Tuberculous Mycobacteria (NTM) are opportunistic human pathogens. Global reports show an emergence of various NTM diseases among immuno-suppressed as well as immuno-competent individuals. In Saudi Arabia, data are scarce on the prevalence of NTM and their genetic diversity. Currently, NTM infections are neglected in the country and the real magnitude of problems is still masked. As the first study of its type to be conducted in Saudi Arabia, we sought to explore the species spectrum of NTM by utilizing a nationwide collection of clinical isolates. The NTM species diversity is large and shows a different trend compared to Western countries as rapidly growing mycobacterial species are the most prevalent to cause diseases in the country. A large number of clinically relevant pulmonary cases show high pathogenic potential of NTM. Indeed, timely identification of mycobacterial species will lead to adapting an appropriate therapy and supports the implementation of control policies which is urgently needed in the country.

Structure of nitrilotriacetate monooxygenase component B from Mycobacterium thermoresistibile

Mycobacterium tuberculosis belongs to a large family of soil bacteria which can degrade a remarkably broad range of organic compounds and utilize them as carbon, nitrogen and energy sources. It has been proposed that a variety of mycobacteria can subsist on alternative carbon sources during latency within an infected human host, with the help of enzymes such as nitrilotriacetate monooxygenase (NTA-Mo). NTA-Mo is a member of a class of enzymes which consist of two components: A and B. While component A has monooxygenase activity and is responsible for the oxidation of the substrate, component B consumes cofactor to generate reduced flavin mononucleotide, which is required for component A activity. NTA-MoB from M. thermoresistibile, a rare but infectious close relative of M. tuberculosis which can thrive at elevated temperatures, has been expressed, purified and crystallized. The 1.6 Å resolution crystal structure of component B of NTA-Mo presented here is one of the first crystal structures determined from the organism M. thermoresistibile. The NTA-MoB crystal structure reveals a homodimer with the characteristic split-barrel motif typical of flavin reductases. Surprisingly, NTA-MoB from M. thermoresistibile contains a C-terminal tail that is highly conserved among mycobacterial orthologs and resides in the active site of the other protomer. Based on the structure, the C-terminal tail may modulate NTA-MoB activity in mycobacteria by blocking the binding of flavins and NADH.

Mycobacterium lentiflavum in drinking water supplies, Australia

Humans may acquire infection from potable water.

Mycobacterium lentiflavum, a slow-growing nontuberculous mycobacterium, is a rare cause of human disease. It has been isolated from environmental samples worldwide. To assess the clinical significance of M. lentiflavum isolates reported to the Queensland Tuberculosis Control Centre, Australia, during 2001–2008, we explored the genotypic similarity and geographic relationship between isolates from humans and potable water in the Brisbane metropolitan area. A total of 47 isolates from 36 patients were reported; 4 patients had clinically significant disease. M. lentiflavum was cultured from 13 of 206 drinking water sites. These sites overlapped geographically with home addresses of the patients who had clinically significant disease. Automated repetitive sequence–based PCR genotyping showed a dominant environmental clone closely related to clinical strains. This finding suggests potable water as a possible source of M. lentiflavum infection in humans.

Non-tuberculous mycobacteria in HIV-negative patients with pulmonary disease in Lisbon, Portugal

Non-tuberculous mycobacteria (NTM) are responsible for an increase in mycobacterial disease in many developed countries. However the epidemiology, especially in patients without HIV infection, remains difficult to determine. We studied a convenience sample of 5497 HIV-negative patients receiving care at our pneumology centres. Among 510 patients with mycobacterial isolates, NTM were demonstrated in 58, all showing signs of lung disease. The mycobacteria isolated were M. intracellulare (n = 9, 15.5%), M. fortuitum (n = 8, 13.8%), M. gordonae (n = 7, 12.1%), M. kansasii (n = 6, 10.3%), M. chelonae (n = 5, 8.6%), M. avium (n = 4, 6.9%), M. abscessus (n = 3, 5.2%), M. peregrinum (n = 3, 5.2%), M. triplex (n = 3, 5.2%), M. spp. (n = 3, 5.2%), M. szulgai (n = 3, 5.2%), M. mucogenicum (n = 2, 3.4%), M. lentiflavum (n = 1, 1.7%) and M. simiae (n = 1, 1.7%). The present high percentage of NTM strains among mycobacterial isolates (approximately 11%), suggests the emergence of NTM infections as a public health problem. Larger, multicentre and multiregional studies or mandatory reporting will be required to better understand the changing epidemiology of NTM in patients with lung disease.

Mycobacterium thermoresistibile: case report of a rarely isolated mycobacterium from Europe and review of literature

Mycobacterium thermoresistibile is a non-tuberculous mycobacterium strongly associated with human infections. Since 1966, there have only been six reports of its isolation from clinical samples. We report on the first case from Europe and review all the previous cases. Identification was achieved with sequencing of the 16S rRNA and hsp65 genes. This study presents its phenotypic and biochemical profile, susceptibilities to selected antibiotics and hsp65 polymerase chain reaction-restriction fragment length polymorphism profile with BsteII and Hae III .