Advances in diagnosis and treatment of non-tuberculous mycobacterial lung disease

The prevalence of Non-tuberculous Mycobacterial Pulmonary Disease (NTM-PD) is increasing worldwide. The advancement in molecular diagnostic technology has greatly promoted the rapid diagnosis of NTM-PD clinically, and the pathogenic strains can be identified to the species level through molecular typing, which provides a reliable basis for treatment. In addition to the well-known PCR and mNGS methods, there are numerous alternative methods to identify NTM to the species level. The treatment of NTM-PD remains a challenging problem. Although clinical guidelines outline several treatment options for common NTM species infections, in most cases, the therapeutic outcomes of these drugs for NTM-PD often fall short of expectations. At present, the focus of research is to find more effective and more tolerable NTM-PD therapeutic drugs and regimens. In this paper, the latest diagnostic techniques, therapeutic drugs and methods, and prevention of NTM-PD are reviewed.

Evaluation of mycobacteria infection prevalence and optimization of the identification process in North Sardinia, Italy

IMPORTANCE

Mycobacterial infection is a major threat to public health worldwide. Accurate identification of infected species and drug resistance detection are critical factors in treatment. We focused on shortening the turn-around time of identifying mycobacteria species and antibiotic resistance tests.

Species-specific identification of Pseudomonas based on 16S-23S rRNA gene internal transcribed spacer (ITS) and its combined application with next-generation sequencing

Background

Pseudomonas species are widely distributed in the human body, animals, plants, soil, fresh water, seawater, etc. Pseudomonas aeruginosa is one of the main pathogens involved in nosocomial infections. It can cause endocarditis, empyema, meningitis, septicaemia and even death. However, the Pseudomonas classification system is currently inadequate and not well established.

Results

In this study, the whole genomes of 103 Pseudomonas strains belonging to 62 species available in GenBank were collected and the specificity of the 16S–23S ribosomal RNA internal transcribed spacer (ITS) sequence was analysed. Secondary structures of ITS transcripts determining where the diversity bases were located were predicted. The alignment results using BLAST indicated that the ITS sequence is specific for most species in the genus. The remaining species were identified by additional frequency analyses based on BLAST results. A double-blind experiment where 200 ITS sequences were randomly selected indicated that this method could identify Pseudomonas species with 100% sensitivity and specificity. In addition, we applied a universal primer to amplify the Pseudomonas ITS of DNA extracts from fish samples with next-generation sequencing. The ITS analysis results were utilized to species-specifically identify the proportion of Pseudomonas species in the samples.

Conclusions

The present study developed a species-specific method identification and classification of Pseudomonas based on ITS sequences combined NGS. The method showed its potential application in other genera.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02607-w.

Mycobacterium salmoniphilum and M. chelonae in Captive Populations of Chinook Salmon

Chinook Salmon Oncorhynchus tshawytscha is a keystone fish species in the Pacific Northwest. In 2019, unusual mortalities occurred in two different populations of cultured fingerlings from the same facility in California, USA. The systems consist of outdoor, enclosed, flow-through freshwater tanks that are maintained at 18 ± 1°C. Clinical signs and gross findings were only observed in one population and included abnormal swimming, inappetence, lethargy, skin discoloration, and the presence of multifocal nodular and ulcerative skin lesions. Microscopic lesions were infrequent and consisted of severe, locally extensive granulomatous dermatitis and myositis and mild, multifocal, granulomatous branchitis, myocarditis, and hepatitis. Intracellular acid-fast organisms were observed within areas of granulomatous myositis. Posterior kidney swabs were collected and inoculated in nutrient-rich and selective agar media and incubated at 25°C for 2 weeks. Visibly pure bacterial colonies were observed 7-10 d postinoculation. Partial sequences of 16S rRNA initially identified the recovered bacteria as members of the genus Mycobacterium. However, marked variability was observed among Mycobacterium spp. isolates by using repetitive extragenic palindromic polymerase chain reaction fingerprinting. Amplification and sequencing of the ribosomal RNA internal transcribed spacer, 65-kDa heat shock protein, and RNA polymerase β-subunit gene of the cultured isolates identified M. salmoniphilum and M. chelonae, discrete members of the M. chelonae-abscessus complex, isolated from diseased Chinook Salmon fingerlings.