Showering is associated with Mycobacterium avium complex lung disease: An observational study in Japanese women

Phylogenetic Profile of Nonulcerans and Nontuberculous Environmental Mycobacteria Isolated in Côte d'Ivoire

BACKGROUND

Environmental mycobacteria are involved in several infections ranging from lung to skin infections. In Côte d'Ivoire, apart from Mycobacterium ulcerans and Mycobacterium tuberculosis, little information exists on other species. The culture of these species, a real challenge, especially in developing countries like Cote d'Ivoire, limits their identification. However, there are reports in literature of infections caused by these mycobacteria, and few species have never been described in human or animal infections. These are difficult cases to treat because of their resistance to most antituberculosis antibiotics. The aim of our work was to study the diversity of potentially pathogenic mycobacterial species in wastewater drainage channels in different townships and in two hospital effluents in the city of Abidjan.

METHODS

Wastewater samples were cultured, followed by conventional polymerase chain reaction (PCR) targeting mycobacterial 16S ribonucleic acid (16S RNA) using PA/MSHA primers. 16 S RNA identified were sequenced by Sanger techniques. Sequences obtained were analyzed, and a phylogenic tree was built.

RESULTS

Fast-growing mycobacteria, including Mycobacterium fortuitum, Mycobacterium phocaicum, Mycobacterium sp., and others presence, were confirmed both by culture and molecular techniques. M. fortuitum strain was the same in effluents of the Treichville University Hospital and in the wastewater of the township of Koumassi. New species never isolated in Côte d'Ivoire, such as M. phocaicum, have been identified in wastewater of the township of Yopougon.

CONCLUSION

This study showed that the sewer network in the city of Abidjan is colonized by both potentially pathogenic mycobacteria and saprophytic environmental mycobacteria.

Shift of human pathogen community composition and their potential human health risk after supply suspension in tap water

Water supply suspension-restoration can occur frequently due to the overhauling of civil infrastructure in developing countries and the shutdown of commercial buildings during the pandemic. For comprehensive insights into the effects of water supply suspension-restoration, this study characterized the variations of the pathogen community composition of the tap water and their infection risk under different water supply scenarios. Metagenomic sequencing revealed a significant change of the human pathogen profiles, among which the most dominant pathogen changed from Pseudomonas aeruginosa (4.91%) to Acinetobacter johnsonii (0.59%). Furthermore, absolute quantification of pathogens by propidium-monoazide-qPCR revealed that the abundance of the three typical pathogens (Pseudomonas aeruginosa, Mycobacterium avium and Salmonella sp.) showed an increase of 2.44 log to 3.60 log immediately after water supply suspension-restoration and did not return to the normal level even after 2-h supply restoration, except for Pseudomonas aeruginosa. Quantitative microbial risk assessment suggested the infection risks of the three pathogens arising from direct utilization of tap water under stable water supply, including dermal exposure and oral intake, were all above the threshold of 10^-4, and evidently increased after water supply suspension-restoration. This study warns us against the risk induced by the pathogens in tap water, especially after water supply suspension-restoration.

Mycobacterium kiyosense sp. nov., a scotochromogenic slow-glowing species isolated from respiratory specimens

Scotochromogenic slow-growing mycobacteria were isolated from the sputum or bronchoalveolar lavage fluid of 12 patients in Japan. From a comparison of the whole-genome sequences, the representative strain IWGMT90018-18076^T and the unknown strains obtained from the patients were found to represent a novel species related to the Mycobacterium gordonae complex. The average nucleotide identity values of IWGMT90018-18076^T with Mycobacterium vicinigordonae, Mycobacterium paragordonae and M. gordonae were 86.7, 82.5 and 82.2 %, respectively. The genome size of the representative strain IWGMT90018-18076^T was approximately 6.3 Mbp, and the genomic DNA G+C content was 67.1 %. The major fatty acid methyl esters were C_16 : 0 (37.71 %), C_18 : 1ω9c (29.5 %) and C_16 : 1ω7c (10.32 %). In this study, we performed phylogenetic analyses, physiological and biochemical characteristic tests, drug susceptibility tests and fatty acid profiling of the clinical isolates. On the basis of the results obtained, we propose that the unknown clinical isolates represent a novel species, 'Mycobacterium kiyosense sp. nov,' with the type strain being IWGMT90018-18076^T (=JCM 34837^T =KCTC 49725^T).

Inactivation of nontuberculous mycobacteria by gaseous ozone treatment

Nontuberculous mycobacteria (NTM) are environmental bacteria resistant to many common disinfectants and ultraviolet radiation. Inhalation of aerosols generated from NTM-containing water and soil causes NTM lung disease, especially in people with underlying lung diseases and decreased immunity. To prevent healthcare-acquired NTM infections, it is important to eradicate NTM living in hospital environments. Therefore, we evaluated the efficacy of gaseous ozone for the inactivation of NTM, namely Mycobacterium (M.) avium, M. intracellulare, M. kansasii, M. abscessus subsp. abscessus and M.abscessus subsp. massiliense. Gaseous ozone treatment at 1 ppm for 3 h reduced the bacterial number of all strains by more than 97%. Gaseous ozone treatment could be a practical, effective and convenient disinfection method for NTM living in hospital environments.

Pathophysiology of pulmonary nontuberculous mycobacterial (NTM) disease

In recent years, the incidence and prevalence of pulmonary nontuberculous mycobacterial (NTM) disease have increased worldwide. Although the reasons for this increase are unclear, dealing with this disease is essential. Pulmonary NTM disease is a chronic pulmonary infection caused by NTM bacteria, which are ubiquitous in various environments. In Japan, Mycobacterium avium-intracellulare complex (MAC) accounts for approximately 90% of the causative organisms of pulmonary NTM disease, which is also called pulmonary MAC disease or pulmonary MAI disease. It is important to elucidate the pathophysiology of this disease, which occurs frequently in postmenopausal women despite the absence of obvious immunodeficiency. The pathophysiology of this disease has not been fully elucidated; however, it can largely be divided into bacterial (environmental) and host-side problems. The host factors can be further divided into immune and airway problems. The authors suggest that the triangular relationship between bacteria, immunity, and the airway is important in the pathophysiology of this disease. The latest findings on the pathophysiology of pulmonary NTM disease are reviewed.