Mycobacterium aurum keratitis: An unusual etiology of a sight-threatening infection

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 13: suitability of taxonomic units notified to EFSA until September 2020

The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of biological agents, intended for addition to food or feed, to support the work of EFSA's Scientific Panels. It is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of knowledge, safety concerns and antimicrobial resistance. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at strain or product level, and reflected by 'qualifications'. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS TUs. Of the 36 microorganisms notified to EFSA between April and September 2020, 33 were excluded; seven filamentous fungi (including Aureobasidium pullulans based on recent taxonomic insights), one Clostridium butyricum, one Enterococcus faecium, three Escherichia coli, one Streptomyces spp. and 20 TUs that had been previously evaluated. Three TUs were evaluated; Methylorubrum extorquens and Mycobacterium aurum for the first time and Bacillus circulans was re-assessed because an update was requested in relation to a new mandate. M. extorquens and M. aurum are not recommended for QPS status due to the lack of a body of knowledge in relation to use in the food or feed chain and M. aurum, due to uncertainty concerning its pathogenicity potential. B. circulans was recommended for QPS status with the qualifications for 'production purposes only' and 'absence of cytotoxic activity'.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

Autoimmune keratitis in mycobacterium tuberculosis

Purpose

To report a case of autoimmune keratitis in a patient with mycobacterium tuberculosis (MBT).

Methods

An 84-year-old male with pulmonary tuberculosis (TB) was admitted with chronic, non-healing bilateral ulcerations of the inferior peripheral cornea associated with stromal and subconjunctival nodules.

Results

Clinical examination revealed circumscribed peripheral corneal ulceration with whitish nodules in adjacent stromal and subconjunctival tissue. Microbiological cultures of the corneal tissue were negative for MBT and other microbial pathogens; however, enzyme-linked immunosorbent assay (ELISA) of blood and corneal samples showed significantly elevated levels of IgM and IgA against MBT. In addition to systemic anti-tuberculosis therapy, the patient was treated topically with Polyspectran^® eye drops, Dexamethasone eye drops, and Bepanthen^® ointment, for 2 weeks. Both eyes showed dramatic improvement after 2 weeks.

Conclusion

The present report demonstrates that MBT is able to initiate delayed autoimmune response within the corneal tissue during an intensive phase of anti-tuberculosis treatment.

Evaluation of greater wax moth larvae, Galleria mellonella, as a novel in vivo model for non-tuberculosis Mycobacteria infections and antibiotic treatments

PURPOSE

To evaluate the suitability of Galleria mellonella larvae as an in vivo model and drug-screening tool for mycobacteria infections.

METHODOLOGY

Larvae were infected using a range of inoculum sizes from a variety of rapid-growing mycobacteria, including strains of M. fortuitum, M. marinum and M. aurum. Larval survival, internal bacterial burden and the effects of amikacin, ciprofloxacin, ethambutol, isoniazid and rifampicin treatment on larval survival were measured over 144 h. The effects of these anti-mycobacterial drugs on phagocytosis and circulating haemocyte numbers were also examined using microscopy.

RESULTS

Larval survival decreased after infection with M. fortuitum and M. marinum in a dose-dependent manner, but remained unaffected by M. aurum. Heat-killed bacteria did not cause larval death. Where antibiotic monotherapy was efficacious, larval survival post-infection increased in a dose-dependent fashion. However, efficacy varied between different antibiotics and species of infecting mycobacteria and, apart from rifampicin, efficacy in vivo correlated poorly with the in vitro minimum inhibitory concentrations (MICs). Combinations of antibiotics led to higher survival of infected larvae than antibiotic monotherapy. Selected antibiotic treatments that enhanced larval survival reduced the overall internal burden of infecting mycobacteria, but did not eradicate the pathogens. Administration of amikacin or ethambutol to uninfected larvae induced an initial transient increase in the numbers of circulating haemocytes and reduced the phagocytic rate of haemocytes in larvae infected with M. marinum.

CONCLUSIONS

This report demonstrates the potential of employing a wax moth larvae model for studying fast-growing mycobacteria infections, and as a cheap, effective system for initial screening of novel treatments.

Verification of Frequency in Species of Nontuberculous Mycobacteria in Kermanshah Drinking Water Supplies Using the PCR-Sequencing Method

BACKGROUND

Nontuberculous mycobacteria are habitants of environment, especially in aquatic systems. Some of them cause problems in immunodeficient patients. Over the last decade, 16S rRNA gene sequencing was established in 45 novel species of nontuberculous mycobacteria. Experiences revealed that this method underestimates the diversity, but does not distinguish between some of mycobacterium subsp. To recognize emerging rapidly growing mycobacteria and identify their subsp, rpoB gene sequencing has been developed.

OBJECTIVES

To better understand the transmission of nontuberculous mycobacterial species from drinking water and preventing the spread of illness with these bacteria, the aim of this study was to detect the presence of bacteria by PCR-sequencing techniques.

MATERIALS AND METHODS

Drinking water samples were collected from different areas of Kermanshah city in west of IRAN. After decontamination with cetylpyridinium chloride, samples were filtered with 0.45-micron filters, the filter transferred directly on growth medium waiting to appear in colonies, then DNA extraction and PCR were performed, and products were sent to sequencing.

RESULTS

We found 35/110 (32%) nontuberculous mycobacterial species in drinking water samples, isolates included Mycobacterium goodii, Mycobacterium aurum, and Mycobacterium gastri with the most abundance (11.5%), followed by Mycobacterium smegmatis, Mycobacterium porcinum, Mycobacterium peregrinum, Mycobacterium mucogenicum, and Mycobacterium chelonae (8%).

CONCLUSIONS

In this study, we recognized the evidence of contamination by nontuberculous mycobacteria in corroded water pipes. As a result of the high prevalence of these bacteria in drinking water in Kermanshah, this is important evidence of transmission through drinking water. This finding can also help public health policy makers control these isolates in drinking water supplies in Kermanshah.

Draft Genome Sequence of Mycobacterium acapulcensis Strain CSURP1424

Mycobacterium acapulcensis is a rapidly growing scotochromogenic acid-fast bacillus. The draft genome of M. acapulcensis CSURP1424 comprises 5,290,974 bp, exhibiting a 66.67% G+C content, 4,870 protein-coding genes, and 71 predicted RNA genes.

The draft genome of Mycobacterium aurum, a potential model organism for investigating drugs against Mycobacterium tuberculosis and Mycobacterium leprae

Mycobacterium aurum (M. aurum) is an environmental mycobacteria that has previously been used in studies of anti-mycobacterial drugs due to its fast growth rate and low pathogenicity. The M. aurum genome has been sequenced and assembled into 46 contigs, with a total length of 6.02Mb containing 5684 annotated protein-coding genes. A phylogenetic analysis using whole genome alignments positioned M. aurum close to Mycobacterium vaccae and Mycobacterium vanbaalenii, within a clade related to fast-growing mycobacteria. Large-scale genomic rearrangements were identified by comparing the M. aurum genome to those of Mycobacterium tuberculosis and Mycobacterium leprae. M. aurum orthologous genes implicated in resistance to anti-tuberculosis drugs in M. tuberculosis were observed. The sequence identity at the DNA level varied from 68.6% for pncA (pyrazinamide drug-related) to 96.2% for rrs (streptomycin, capreomycin). We observed two homologous genes encoding the catalase-peroxidase enzyme (katG) that is associated with resistance to isoniazid. Similarly, two embB homologues were identified in the M. aurum genome. In addition to describing for the first time the genome of M. aurum, this work provides a resource to aid the use of M. aurum in studies to develop improved drugs for the pathogenic mycobacteria M. tuberculosis and M. leprae.

Nontuberculous Mycobacteria Isolation from Clinical and Environmental Samples in Iran: Twenty Years of Surveillance

Nontuberculous mycobacteria (NTM) are opportunistic pathogens that are widely distributed in the environment. There is a lack of data on species distribution of these organisms from Iran. This study consists of a review of NTM articles published in Iran between the years 1992 and 2014. In this review, 20 articles and 14 case reports were identified. Among the 20 articles, 13 (65%) studies focused on NTM isolates from clinical specimens, 6 (30%) studies examined NTM isolates from environmental samples, and one (5%) article included both clinical and environmental isolates. M. fortuitum (229/997; 23%) was recorded as the most prevalent and rapid growing mycobacteria (RGM) species in both clinical (28%) and environmental (19%) isolated samples (P < 0.05). Among slow growing mycobacteria (SGM), M. simiae (103/494; 21%) demonstrated a higher frequency in clinical samples whereas in environmental samples it was M. flavescens (44/503; 9%). These data represent information from 14 provinces out of 31 provinces of Iran. No information is available in current published data on clinical or environmental NTM from the remaining 17 provinces in Iran. These results emphasize the potential importance of NTM as well as the underestimation of NTM frequency in Iran. NTM is an important clinical problem associated with significant morbidity and mortality in Iran. Continued research is needed from both clinical and environmental sources to help clinicians and researchers better understand and address NTM treatment and prevention.

Nontuberculous Mycobacterial Ocular Infections: A Systematic Review of the Literature

Nontuberculous or atypical mycobacterial ocular infections have been increasing in prevalence over the past few decades. They are known to cause periocular, adnexal, ocular surface and intraocular infections and are often recalcitrant to medical therapy. These infections can potentially cause detrimental outcomes, in part due to a delay in diagnosis. We review 174 case reports and series on nontuberculous mycobacterial (NTM) ocular infections and discuss etiology, microbiology, risk factors, diagnosis, clinical presentation, and treatment of these infections. History of interventions, trauma, foreign bodies, implants, contact lenses, and steroids are linked to NTM ocular infections. Steroid use may prolong the duration of the infection and cause poorer visual outcomes. Early diagnosis and initiation of treatment with multiple antibiotics are necessary to achieve the best visual outcome.

Nontuberculous mycobacteria in Middle East: Current situation and future challenges

Nontuberculous mycobacteria (NTM) are a diverse group of bacterial species that are distributed in the environment. Many of these environmental bacteria can cause disease in humans. The identification of NTM in environmental sources is important for both clinical and epidemiological purposes. In this study, the distribution of NTM species from environmental and clinical samples in the Middle East was reviewed. In order to provide an overview of NTM, as well as recent epidemiological trends, all studies addressing NTM in the Middle East from 1984 to 2014 were reviewed. A total of 96 articles were found, in which 1751 NTM strains were isolated and 1084 of which were obtained from clinical samples, 619 from environmental samples and 48 were cited by case reports. Mycobacterium fortuitum was the most common rapid growing mycobacteria (RGM) isolated from both clinical (269 out of 447 RGM; 60.1%) and environmental (135 out of 289 RGM; 46.7%) samples. Mycobacterium avium complex (MAC) was the most common slow growing mycobacteria (SGM) isolated from clinical samples (140 out of 637 SGM; 21.9%). An increasing trend in NTM isolation from the Middle East was noted over the last 5years. This review demonstrates the increasing concern regarding NTM disease in the Middle East, emphasizing the need for regional collaboration and coordination in order to respond appropriately.