Disseminated Disease by Mycobacterium abscessus and Mycobacterium celatum in an Immunocompromised Host

Epidemiological and clinical characteristics of nontuberculous mycobacterial infections: A retrospective female cohort study in an Italian population

Objectives

This study aims to assess the characteristics and treatment outcomes of patients diagnosed with non-tuberculous mycobacteria (NTM) diseases at the Infectious Diseases Unit of ARNAS Garibaldi Hospital in Catania, Italy, focusing on demographics, clinical features, and treatment effectiveness.

Methods

We conducted a retrospective observational study of 10 patients diagnosed with NTM diseases between 2019 and 2021. Data was collected from electronic medical records, including demographic information, comorbidities, treatment modalities, and outcomes. The study utilized descriptive statistics to analyze continuous and categorical variables. Treatment regimens were based on individual patient needs, incorporating a combination of antibiotics.

Results

The median age of the patients was 55.44 years, all female, predominantly suffering from pulmonary NTM diseases. Mycobacterium intracellulare was the most common pathogen. Common comorbidities included COPD, bronchiectasis, GERD, and hypovitaminosis D. Patients showed symptoms like fever, cough, and asthenia. The treatment regimens were diverse, with macrolides, rifampicin, and ethambutol forming the core. Adverse effects were noted in 40 % of patients, including gastrointestinal and neurological disorders. All patients achieved microbiological cure, with 60 % showing clinical improvement and 36 % radiological improvement.

Conclusion

The study highlights the complexity of diagnosing and treating NTM diseases, emphasizing the need for personalized treatment plans and vigilant monitoring of adverse effects. Despite achieving microbiological cure, challenges remain in achieving complete clinical and radiological resolution. Further research is needed to enhance the understanding and management of NTM diseases, particularly in diverse populations.

Risk of zoonoses involving slow-growing non-tuberculous mycobacteria: Survey of antimicrobial resistance among strains from domestic and wild animals

OBJECTIVES

Non-tuberculous mycobacteria are opportunistic pathogens that cause disease mainly in immunocompromised hosts. The present study assessed the prevalence of antibiotic resistance among such mycobacteria from domestic and wild animals in Croatia sampled during several years within a national surveillance program.

METHODS

A total of 44 isolates belonging to nine slow-growing species were genotyped and analyzed for susceptibility to 13 antimicrobials often used to treat non-tuberculous mycobacterial infections in humans.

RESULTS

Most prevalent resistance was to moxifloxacin (77.3%), doxycycline (76.9%), and rifampicin (76.9%), followed by ciprofloxacin (65.4%), trimethoprim-sulfamethoxazole (65.4%), and linezolid (61.4%). Few isolates were resistant to rifabutin (7.7%) or amikacin (6.8%). None of the isolates was resistant to clarithromycin. Nearly all isolates (86.4%) were resistant to multiple antibiotics.

CONCLUSION

Our findings suggest substantial risk that human populations may experience zoonotic infections with non-tuberculous mycobacteria that will be difficult to treat using the current generation of antibiotics. Future work should clarify how resistance emerges in wild populations of non-tuberculous mycobacteria.

Understanding the Phage-Host Interaction Mechanism toward Improving the Efficacy of Current Antibiotics in Mycobacterium abscessus

Pulmonary infections caused by Mycobacterium abscessus (MAB) have been increasing in incidence in recent years, leading to chronic and many times fatal infections due to MAB's natural resistance to most available antimicrobials. The use of bacteriophages (phages) in clinics is emerging as a novel treatment strategy to save the lives of patients suffering from drug-resistant, chronic, and disseminated infections. The substantial research indicates that phage-antibiotic combination therapy can display synergy and be clinically more effective than phage therapy alone. However, there is limited knowledge in the understanding of the molecular mechanisms in phage-mycobacteria interaction and the synergism of phage-antibiotic combinations. We generated the lytic mycobacteriophage library and studied phage specificity and the host range in MAB clinical isolates and characterized the phage's ability to lyse the pathogen under various environmental and mammalian host stress conditions. Our results indicate that phage lytic efficiency is altered by environmental conditions, especially in conditions of biofilm and intracellular states of MAB. By utilizing the MAB gene knockout mutants of the MAB_0937c/MmpL10 drug efflux pump and MAB_0939/pks polyketide synthase enzyme, we discovered the surface glycolipid diacyltrehalose/polyacyltrehalose (DAT/PAT) as one of the major primary phage receptors in mycobacteria. We also established a set of phages that alter the MmpL10 multidrug efflux pump function in MAB through an evolutionary trade-off mechanism. The combination of these phages with antibiotics significantly decreases the number of viable bacteria when compared to phage or antibiotic-alone treatments. This study deepens our understanding of phage-mycobacteria interaction mechanisms and identifies therapeutic phages that can lower bacterial fitness by impairing an antibiotic efflux function and attenuating the MAB intrinsic resistance mechanism via targeted therapy.

Mycobacterium abscessus Complex Osteomyelitis of the Wrist

Mycobacterium abscessus (M. abscessus) is a ubiquitous, rapidly growing non-tuberculous mycobacterium, which is known to cause life-threatening lung infections in immunocompromised individuals following exposure to contaminated injectable products. We report a case of M. abscessus osteomyelitis of the right wrist in a 28-year-old patient with a history of intravenous drug use and a recent surgical repair of the right radial artery pseudoaneurysm. The patient underwent surgical debridement of the right distal radius infection. Histopathological examination and culture of the debrided tissue revealed M. abscessus complex infection. The patient was placed on intravenous amikacin, azithromycin, and cefoxitin for six weeks, followed by oral linezolid and clofazimine for six months.

Mycobacterium abscessus: insights from a bioinformatic perspective

Mycobacterium abscessus is a nontuberculous mycobacterium, associated with broncho-pulmonary infections in individuals suffering from cystic fibrosis, bronchiectasis, and pulmonary diseases. The risk factors for transmission include biofilms, contaminated water resources, fomites, and infected individuals. M. abscessus is extensively resistant to antibiotics. To date, there is no vaccine and combination antibiotic therapy is followed. However, drug toxicities, low cure rates, and high cost of treatment make it imperfect. Over the last 20 years, bioinformatic studies on M. abscessus have advanced our understanding of the pathogen. This review integrates knowledge from the analysis of genomes, microbiomes, genomic variations, phylogeny, proteome, transcriptome, secretome, antibiotic resistance, and vaccine design to further our understanding. The utility of genome-based studies in comprehending disease progression, surveillance, tracing transmission routes, and epidemiological outbreaks on a global scale has been highlighted. Furthermore, this review underlined the importance of using computational methodologies for pinpointing factors responsible for pathogen survival and resistance. We reiterate the significance of interdisciplinary research to fight M. abscessus. In a nutshell, the outcome of computational studies can go a long way in creating novel therapeutic avenues to control M. abscessus mediated pulmonary infections.