Nontuberculous mycobacterial ocular infections--comparing the clinical and microbiological characteristics between Mycobacterium abscessus and Mycobacterium massiliense

Lacrimal Canaliculitis: A Major Review

Lacrimal canaliculitis is an inflammation of the proximal lacrimal drainage system. It classically presents with symptoms of redness, mucopurulent discharge, medial canthal swelling, epiphora, and pouting punctum. Despite having classical clinical characteristics it is frequently misdiagnosed. The cause can be primarily due to various infectious agents or secondary mostly due to the use of punctal plugs. There are no universally accepted guidelines for the management of canaliculitis but different medical and surgical options have been employed with varying success rates and it is notorious for recurrences and failure to therapy. The present review summarizes the existing literature on lacrimal canaliculitis published over the past 15 years to provide an overview of this uncommon condition. A total of 100 articles published in the literature were anlaysed during this period. The mean age at diagnosis was 57.09 ± 16.91 years with a female preponderance. Misdiagnosis was common with many patients misdiagnosed as conjunctivitis and dacryocystitis. Primary canaliculitis was found to be more frequent than secondary with inferior canaliculus involved more commonly than the superior. Staphylococcus, Streptococcus, and Actinomyces were the most common microbes isolated. Surgical management was employed in 74.25% of cases while medical management was done in 20.82% of cases. The review presents an insight into the complexities of canaliculitis, its diagnosis, and management which will further help to improve the understanding of this uncommon infection of the lacrimal system.

Omadacycline for management of Mycobacterium abscessus infections: a review of its effectiveness, place in therapy, and considerations for use

The Mycobacterium abscessus complex (MABC) is a group of acid-fast, rapidly dividing non-tuberculous mycobacteria (NTM) that include a number of clinically important subspecies, including M. abscessus, M. bolletii, and M. massiliense. These organisms are prevalent in the environment and are primarily associated with human pulmonary or skin and skin structure infections (SSSI) but may cause more deep-seeded disseminated infections and bacteremia in the immunocompromised. Importantly, these NTM are resistant to most first-line anti-tuberculous agents and, due to intrinsic or acquired resistance, exhibit exceedingly low, variable, and geographically distinct susceptibilities to commonly used antibacterial agents including older tetracyclines, macrolides, aminoglycosides, cephalosporins, carbapenems, and sulfamethoxazole-trimethoprim. Omadacycline is a novel third-generation member of the tetracycline family of antibacterials that has recently been demonstrated to have potent anti-NTM effects and clinical efficacy against MABC, including M. abscessus. The purpose of this review is to present a comprehensive and up-to-date assessment on the body of literature on the role of omadacycline for M. abscessus infections. Specifically, the in vitro and in vivo microbiology, mechanisms of action, mechanisms of resistance, clinical pharmacokinetics, clinical efficacy, adverse effects, dosage and administration, and place in therapy of omadacycline in management of M. abscessus infections will be detailed.

HMGN2 regulates non-tuberculous mycobacteria survival via modulation of M1 macrophage polarization

Non‐tuberculous mycobacteria (NTM), also known as an environmental and atypical mycobacteria, can cause the chronic pulmonary infectious diseases. Macrophages have been suggested as the main host cell to initiate the innate immune responses to NTM infection. However, the molecular mechanism to regulate the antimicrobial immune responses to NTM is still largely unknown. Current study showed that the NTM clinical groups, Mycobacterium abscessus and Mycobacterium smegmatis, significantly induced the M1 macrophage polarization with the characteristic production of nitric oxide (NO) and marker gene expression of iNOS, IFNγ, TNF‐α, IL1‐β and IL‐6. Interestingly, a non‐histone nuclear protein, HMGN2 (high‐mobility group N2), was found to be spontaneously induced during NTM‐activated M1 macrophage polarization. Functional studies revealed that HMGN2 deficiency in NTM‐infected macrophage promotes the expression of M1 markers and the production of NO via the enhanced activation of NF‐κB and MAPK signalling. Further studies exhibited that HMGN2 knock‐down also enhanced IFNγ‐induced M1 macrophage polarization. Finally, we observed that silencing HMGN2 affected the survival of NTM in macrophage, which might largely relevant to enhanced macrophage polarization into M1 phenotype under the NTM infection. Collectively, current studies thus suggested a novel function of HMGN2 in regulating the anti‐non‐tuberculous mycobacteria innate immunity of macrophage.

Postoperative Mycobacteroides abscessus subsp. abscessus endophthalmitis: Clinical analysis of 12 clustered adults and a proposed therapeutic algorithm

PURPOSE

Postoperative endophthalmitis caused by nontuberculous mycobacterium is a rare but devastating complication after intraocular surgery. However, optimal treatment strategies remain undetermined in view of its rarity.

METHODS

We investigated the cases of culture-proven postoperative Mycobacteroides abscessus subsp. abscessus endophthalmitis in southern Taiwan, focusing on clinical manifestations and microbiological study, and aimed to describe clinical staging and to propose a therapeutic modality for this disease.

RESULTS

Twelve cases, including two published cases, were treated in two medical centers in southern Taiwan between Aug. 2011 and Dec. 2016, and all ever received cataract surgery at one clinic. Their disease courses could be categorized into four distinct stages, i.e., the initial, quiescent, recurrent, and end stage, and some cases experienced 1-4 cycles of quiescent-recurrent stages. Although all eyes ended up with phthisis or were eviscerated, the affected eyes receiving pars plana vitrectomy (PPV) tended to become quiescent and survived longer than those without PPV (adjusted hazard ratio: 13.9, p < 0.05). Eight isolates of eight patients were available for microbiological study. All isolates were susceptible to amikacin, and inducible clarithromycin resistance was observed in 100% of isolates.

CONCLUSION

Despite the preservation of vision in postoperative M.abscessus endophthalmitis remained a challenge, a stage-based approach is proposed, which may facilitate decision-makings for the future study.

Mycobacterium abscessus: Shapeshifter of the Mycobacterial World

In this review we will focus on unique aspects of Mycobacterium abscessus (MABS) which we feel earn it the designation of "shapeshifter of the mycobacterial world." We will review its emergence as a distinct species, the recognition and description of MABS subspecies which are only now being clearly defined in terms of pathogenicity, its ability to exist in different forms favoring a saprophytic lifestyle or one more suitable to invasion of mammalian hosts, as well as current challenges in terms of antimicrobial therapy and future directions for research. One can see in the various phases of MABS, a species transitioning from a free living saprophyte to a host-adapted pathogen.

Mycobacterium abscessus Infections in Children: A Review of Current Literature

There is limited literature on Mycobacterium abscessus infections in children and limited data about its diagnosis and management. The incidence of infections due to M abscessus appears to be increasing in certain populations and can be a significant cause of morbidity and mortality.Management of these infections is challenging and relies on combination antimicrobial therapy and debridement of diseased tissue, depending on the site and extent of disease. Treatment regimens often are difficult to tolerate, and the antimicrobials used can cause significant adverse effects, particularly given the long duration of therapy needed.This review summarizes the literature and includes information from our own institution's experience on pediatric M abscessus infections including the epidemiology, transmission, clinical manifestations, and the management of these infections. Adult data have been used where there are limited pediatric data. Further studies regarding epidemiology and risk factors, clinical presentation, optimal treatment, and outcomes in children are necessary.

Infections caused by Mycobacterium abscessus: epidemiology, diagnostic tools and treatment

INTRODUCTION

Mycobacterium abscessus is an emerging mycobacteria that is responsible for lung diseases and healthcare-associated extrapulmonary infections. Recent findings support its taxonomic status as a single species comprising 3 subspecies designated abscessus, bolletii and massiliense. We performed a review of English-language publications investigating all three of these subspecies. Areas covered: Worldwide, human infections are often attributable to environmental contamination, although the isolation of M. abscessus in this reservoir is very rare. Basic research has demonstrated an association between virulence and cell wall components and cording, and genome analysis has identified gene transfer from other bacteria. The bacteriological diagnosis of M. abscessus is based on innovative tools combining molecular biology and mass spectrometry. Genotypic and phenotypic susceptibility testing are required to predict the success of macrolide (clarithromycin or azithromycin)-based therapeutic regimens. Genotyping methods are helpful to assess relapse and cross-transmission and to search for a common source. Treatment is not standardised, and outcomes are often unsatisfactory. Expert commentary: M. abscessus is still an open field in terms of clinical and bacteriological research. Further knowledge of its ecology and transmission routes, as well as host-pathogen interactions, is required. Because the number of human cases is increasing, it is also necessary to identify more active treatments and perform clinical trials to assess standard effective regimens.

A cluster of Mycobacterium massiliense keratitis in foundry workers

Three consecutive workers from the same foundry had Mycobacterium massiliense keratitis. The strains isolated from each patient were identical. This is the first report of a non-surgery-related outbreak of non-tuberculous mycobacterial ocular infection. An investigation revealed that injured cornea with exposure to aerosolized non-tuberculous mycobacteria might account for this outbreak.