Pulmonary infection caused by Mycobacterium conceptionense

Characterization of Chemical Interactions between Clinical Drugs and the Oral Bacterium, Corynebacterium matruchotii, via Bioactivity-HiTES

In the field of natural product research, the rediscovery of already-known compounds is one of the significant issues hindering new drug development. Recently, an innovative approach called bioactivity-HiTES has been developed to overcome this limitation, and several new bioactive metabolites have been successfully characterized by this method. In this study, we applied bioactivity-HiTES to Corynebacterium matruchotii, the human oral bacterium, with 3120 clinical drugs as potential elicitors. As a result, we identified two cryptic metabolites, methylindole-3-acetate (MIAA) and indole-3-acetic acid (IAA), elicited by imidafenacin, a urinary antispasmodic drug approved by the Japanese Pharmaceuticals and Medical Devices Agency (PMDA). MIAA showed weak antibacterial activity against a pulmonary disease-causing Mycobacterium conceptionense with an IC50 value of 185.7 μM. Unexpectedly, we also found that C. matruchotii metabolized fludarabine phosphate, a USFDA-approved anticancer drug, to 2-fluoroadenine which displayed moderate antibacterial activity against both Bacillus subtilis and Escherichia coli, with IC50 values of 8.9 and 20.1 μM, respectively. Finally, acelarin, a prodrug of the anticancer drug gemcitabine, was found to exhibit unreported antibacterial activity against B. subtilis with an IC50 value of 33.6 μM through the bioactivity-HiTES method as well. These results indicate that bioactivity-HiTES can also be applied to discover biotransformed products in addition to finding cryptic metabolites in microbes.

Mycobacterium senegalense Infection in Kidney Transplant Patient with Diabetes, Memphis, Tennessee, USA

Fewer than 30 cases of Mycobacterium senegalense infection have been reported. We report a complicated case of M. senegalense infection in Memphis, Tennessee, in the southeastern United States. The patient's comorbidities of past organ transplant and insulin-dependent diabetes required delicate consideration of those health conditions to guide treatment.

Molecular epidemiology of nontuberculous mycobacteria isolated from tuberculosis-suspected patients

It is a growing problem around the world to deal with nontuberculous mycobacteria infection (NTM), but its clinical significance is still largely unknown. This study aims to investigate the epidemiology of NTM infections from various clinical samples and determine their clinical significance. From December 2020 to December 2021, 6125 clinical samples were collected. In addition to phenotypic detection, genotypic detection through multilocus sequence typing (hsp65, rpoB, and 16S rDNA genes) and sequencing was also conducted. Records of patients were consulted for clinical information, such as symptoms and radiological findings. Of the 6,125 patients, 351 (5.7%) were positive for acid-fast bacteria (AFB). Out of 351 AFB, 289 (82.3%) and 62 (17.7%) subjects were identified as M. tuberculosis complex (MTC) and NTM strains, respectively. Isolates of Mycobacterium simiae and M. fortuitum were the most frequent, followed by isolates of M. kansasii and M. marinum. We also isolated M. chelonae, M. canariasense, and M. jacuzzii, which are rarely reported. Symptoms (P = 0.048), radiographic findings (P = 0.013), and gender (P = 0.039) were associated with NTM isolates. M. Fortuitum, M. simiae, and M. kansasii presented with bronchiectasis, infiltration, and cavitary lesions most frequently, while cough was the most common symptom. In conclusion, Mycobacterium simiae and M. fortuitum were presented in seventeen and twelve NTM isolates from the collected samples. There is evidence that NTM infections in endemic settings may contribute to the dissemination of various diseases and the control of tuberculosis. In spite of this, further research is needed to evaluate the clinical significance of NTM isolates.

General characteristics, features of cultivation and antibiotic resistance representatives of mycobacterium fortuitum group representatives (review of literature)

Recently, more and more scientific works have been devoted to non-tuberculous mycobacteria, both by domestic and foreign researchers. One of the main reasons for this is the increase in patients with immunosuppression of various origins, improvement of the quality of laboratory and instrumental diagnostics of mycobacteriosis. This article focuses on the representatives of the M. fortuitum group, as the main pathogens among the group of fast-growing mycobacteria. The data on the modern classification based on the use of molecular genetic studies are indicated. The M. fortuitum group includes: Mycobacterium fortuitum, M. peregrinum, M. senegalense, M. porcinum, M. houstonense, M. neworleansense, M. boenickei, M. conceptionense, M. septicum, M. alvei. According to the new data, mycobacteria were divided into 5 clades (Abscessus-Chelonae, Fortuitum-Vaccae, Terrae, Triviale, Tuberculosis-Simiae), and based on molecular genetic studies, new genera in the Mycobacteriaceae family were isolated: Mycolicibacter spp., Mycolicibacillus spp., Mycolicibacillus spp., Mycobacteroides spp., Mycolicibacterium spp. In accordance with the new classification, representatives of the Mycobacterium fortuitum group belong to the genus Mycolicibacterium. The main epidemiological features of the main sources of the spread of mycobacteria, factors and ways of their transmission are indicated. Due to their wide distribution in the environment, representatives of the M. fortuitum group are capable of causing diseases of the pulmonary and extrapulmonary localization. The distinctive features of pathogenicity factors, due to which the course of the disease is determined, are noted. The article also indicates the main difficulties and features of determining the sensitivity to antimicrobial chemotherapy drugs, provides data on the main features of antibiotic resistance of M.fortuitum group. In preparing the review, literature sources obtained from international and domestic databases were used: Scopus, Web of Science, Springer, RSCI.

Mycobacterium conceptionense Pneumonitis in Patient with HIV/AIDS1

Approximately 21 human cases of infection with Mycobacterium conceptionense have been reported. However, most cases were outside the United States, and optimal treatment remains uncertain. We report a case of M. conceptionense pneumonitis in a patient with HIV/AIDS in the United States. The patient was cured with azithromycin and doxycycline.

Clusters of nontuberculous mycobacteria linked to water sources at three Veterans Affairs medical centers

Objective:

To characterize nontuberculous mycobacteria (NTM) associated with case clusters at 3 medical facilities.

Design:

Retrospective cohort study using molecular typing of patient and water isolates.

Setting:

Veterans Affairs Medical Centers (VAMCs).

Methods:

Isolation and identification of NTM from clinical and water samples using culture, MALDI-TOF, and gene population sequencing to determine species and genetic relatedness. Clinical data were abstracted from electronic health records.

Results:

An identical strain of Mycobacterium conceptionense was isolated from 41 patients at VA Medical Centers (VAMCs A, B, and D), and from VAMC A’s ICU ice machine. Isolates were initially identified as other NTM species within the M. fortuitum clade. Sequencing analyses revealed that they were identical M. conceptionense strains. Overall, 7 patients (17%) met the criteria for pulmonary or nonpulmonary infection with NTM, and 13 of 41 (32%) were treated with effective antimicrobials regardless of infection or colonization status. Separately, a M. mucogenicum patient strain from VAMC A matched a strain isolated from a VAMC B ICU ice machine. VAMC C, in a different state, had a 4-patient cluster with Mycobacterium porcinum. Strains were identical to those isolated from sink-water samples at this facility.

Conclusion:

NTM from hospital water systems are found in hospitalized patients, often during workup for other infections, making attribution of NTM infection problematic. Variable NTM identification methods and changing taxonomy create challenges for epidemiologic investigation and linkage to environmental sources.

Evaluating the clinical significance of nontuberculous mycobacteria isolated from respiratory samples in Iran: an often overlooked disease

Purpose

Nontuberculous mycobacteria (NTM) infection is an increasing problem worldwide whose clinical significance is still largely unknown. The aim of this study was to investigate the epidemiology of NTM infection from respiratory samples and to determine their clinical significance.

Patients and methods

This cross-sectional study was performed on 7,825 clinical samples from December 2015 to December 2017. Detection was conducted using phenotypic and genotypic (hsp65 PCR-RFLP, rpoB, and 16S rRNA genes sequencing) methods. All clinical information including symptoms and radiological findings was extracted from patients’ records.

Results

A total of 478 were confirmed to have respiratory samples which were culture positive for mycobacteria, with the prevalence of NTM infection obtained as 53 (11.1%). Overall, Mycobacterium (M.) fortuitum was the most frequent NTM isolate, followed by M. simiae, M. kansasii, M. gordonae, and M. conceptionense. There was a relationship between NTM isolates and gender (P=0.039), symptoms (P=0.048), and radiographic findings (P=0.013). Bronchiectasis, infiltration, and cavitary lesion were the most frequent radiological findings in M. fortuitum, M. simiae, and M. kansasii, respectively, with cough being the most frequent symptom.

Conclusion

We reported five different NTM isolates in respiratory samples with a high frequency of M. fortuitum. NTM infections may play an important role in causing pulmonary disease and in tuberculosis management in endemic settings. Nevertheless, more studies are required to further examine the clinical significance of NTM isolates.

Species Distribution and Macrolide Susceptibility of Mycobacterium fortuitum Complex Clinical Isolates

The understanding of species distribution and inducible macrolide resistance in the Mycobacterium fortuitum complex (MFC) is limited. Of 90 mostly respiratory MFC clinical isolates, half were M. fortuitum, followed by M. peregrinum, M. porcinum, M. septicum, and M. conceptionense Most M. fortuitum, M. por cinum, and M. septicum isolates were inducibly resistant to clarithromycin, whereas two-thirds of the M. peregrinum isolates were clarithromycin susceptible. Clarithromycin-resistant M. fortuitum isolates exhibited common mutations of erm(39), potentially involved in clarithromycin resistance.

Mycobacterium conceptionense Bloodstream Infection in a Patient with Advanced Gastric Carcinoma

A 65-year-old Japanese male farmer with advanced gastric adenocarcinoma and multiple hepatic metastases was admitted to our hospital. Blood culture results were positive on day 5, and Gram-positive rods were detected. According to the results of Ziehl-Neelsen staining and a cultured colony of this bacterium, we suspected a mycobacterial infection. Suspecting a rapidly growing mycobacterium (RGM), we started multidrug therapy with levofloxacin, clarithromycin, and ethambutol, and the patient recovered from the bloodstream infection. Further gene examination (16S rRNA, hsp65, and sodA) revealed an isolate of Mycobacterium conceptionense. M. conceptionense was first identified as an RGM in 2006. Among previous case reports of M. conceptionense infections, bone and soft tissue infections in hosts with a disorder of the normal structure (e.g., surgical sites) were dominant. We report the characteristics of M. conceptionense infection in this first Japanese case report and a review of the literature.

Frequency and clinical implications of the isolation of rare nontuberculous mycobacteria

Background

To date, more than 125 species of nontuberculous mycobacteria (NTM) have been identified. In this study, we investigated the frequency and clinical implication of the rarely isolated NTM from respiratory specimens.

Methods

Patients with NTM isolated from their respiratory specimens between July 1, 2010 and June 31, 2012 were screened for inclusion. Rare NTM were defined as those NTM not falling within the group of eight NTM species commonly identified at our institution: Mycobacterium avium, M. intracellulare, M. abscessus, M. massiliense, M. fortuitum, M. kansasii, M. gordonae, and M. peregrinum. Clinical, radiographic and microbiological data from patients with rare NTM were reviewed and analyzed.

Results

During the study period, 73 rare NTM were isolated from the respiratory specimens of 68 patients. Among these, M. conceptionense was the most common (nine patients, 12.3%). The median age of the 68 patients with rare NTM was 68 years, while 39 of the patients were male. Rare NTM were isolated only once in majority of patient (64 patients, 94.1%). Among the four patients from whom rare NTM were isolated two or more times, only two showed radiographic aggravation caused by rare NTM during the follow-up period.

Conclusions

Most of the rarely identified NTM species were isolated from respiratory specimens only once per patient, without concomitant clinical aggravation. Clinicians could therefore observe such patients closely without invasive work-ups or treatment, provided the patients do not have decreased host immunity towards mycobacteria.

Nontuberculous mycobacteria in freshwater fish and fish products intended for human consumption

Nontuberculous mycobacteria (NTM) are potentially pathogenic agents commonly found in natural ecosystems, while food is considered to be another source of NTM for humans. We investigated a total of 92 tissue samples of freshwater fish and fish products: fish directly obtained from ponds (n=25), retail fresh (n=23) and frozen fish (n=23) and smoked fish products (n=21). Culture examination for the presence of mycobacteria was positive in 11 (11.9%) from all the examined samples. The 15 obtained isolates were identified as Mycobacterium fortuitum (n=5), M. immunogenum (n=2), M. phocaicum/ mucogenicum (n=1), M. neoaurum (n=2), M. peregrinum (n=2), M. porcinum (n=1) and M. senegalense/houstonense/conceptionense (n=2). NTM DNA was found in one (4.0%) sample of fresh fish from ponds and in 60.9% and 91.3% of retail fresh and frozen fish, respectively. None of the smoked fish products contained NTM DNA. The results of our study suggest that freshwater fish and fish products, especially retail frozen fish, might be a reservoir of NTM for humans, and proper handling and treatment before consumption of such products is recommended.