Mycobacterium obuense Bacteremia in a Patient with Pneumonia

Optimizing antigen selection for the development of tuberculosis vaccines

Tuberculosis (TB) remains a prevalent global infectious disease caused by genetically closely related tubercle bacilli in Mycobacterium tuberculosis complex (MTBC). For a century, the Bacillus Calmette-Guérin (BCG) vaccine has been the primary preventive measure against TB. While it effectively protects against extrapulmonary forms of pediatric TB, it lacks consistent efficacy in providing protection against pulmonary TB in adults. Consequently, the exploration and development of novel TB vaccines, capable of providing broad protection to populations, have consistently constituted a prominent area of interest in medical research. This article presents a concise overview of the novel TB vaccines currently undergoing clinical trials, discussing their classification, protective efficacy, immunogenicity, advantages, and limitations. In vaccine development, the careful selection of antigens that can induce strong and diverse specific immune responses is essential. Therefore, we have summarized the molecular characteristics, biological function, immunogenicity, and relevant studies associated with the chosen antigens for TB vaccines. These insights gained from vaccines and immunogenic proteins will inform the development of novel mycobacterial vaccines, particularly mRNA vaccines, for effective TB control.

Disseminated non-tuberculous mycobacterial infection caused by Mycobacterium obuense in an immunocompromised patient: a case report

BACKGROUND

Mycobacterium obuense (M. obuense) is a rapidly growing mycobacterium (RGM) which has been considered nonpathogenic. Here, we report a case of disseminated non-tuberculous mycobacterial (NTM) infection caused by M. obuense in an immunocompromised patient.

CASE PRESENTATION

A 16-year-old boy was referred to our hospital due to acute myeloid leukemia. During the treatment of leukemia, the patient exhibited continuous fever, and diffuse miliary nodules with random distribution were found on chest computed tomography. Repeated examinations of bacterial culture tests revealed sputum and urine samples to be smear-positive for acid-fast bacillus, and blood culture from a peripherally inserted central catheter line showed the growth of NTM. The NTM species was identified as M. obuense by mass spectrometry and confirmed by genome sequencing. Combination therapy with amikacin, rifampicin, azithromycin, and moxifloxacin significantly improved the patient's symptoms and radiological findings.

CONCLUSION

We report a case of disseminated NTM infection caused by M. obuense for which combination anti-microbial therapy was effective. An immunocompromised host indwelling catheter is at risk of RGM bloodstream infections. Although relatively rare, M. obuense may be considered as a potential pathogen causing infectious diseases, especially in high-risk patients.

A nontuberculous mycobacterium could solve the mystery of the lady from the Franciscan church in Basel, Switzerland

BACKGROUND

In 1975, the mummified body of a female has been found in the Franciscan church in Basel, Switzerland. Molecular and genealogic analyses unveiled her identity as Anna Catharina Bischoff (ACB), a member of the upper class of post-reformed Basel, who died at the age of 68 years, in 1787. The reason behind her death is still a mystery, especially that toxicological analyses revealed high levels of mercury, a common treatment against infections at that time, in different body organs. The computed tomography (CT) and histological analysis showed bone lesions in the femurs, the rib cage, and the skull, which refers to a potential syphilis case.

RESULTS

Although we could not detect any molecular signs of the syphilis-causing pathogen Treponema pallidum subsp. pallidum, we realized high prevalence of a nontuberculous mycobacterium (NTM) species in brain tissue sample. The genome analysis of this NTM displayed richness of virulence genes and toxins, and similarity to other infectious NTM, known to infect immunocompromised patients. In addition, it displayed potential resistance to mercury compounds, which might indicate a selective advantage against the applied treatment. This suggests that ACB might have suffered from an atypical mycobacteriosis during her life, which could explain the mummy's bone lesion and high mercury concentrations.

CONCLUSIONS

The study of this mummy exemplifies the importance of employing differential diagnostic approaches in paleopathological analysis, by combining classical anthropological, radiological, histological, and toxicological observations with molecular analysis. It represents a proof-of-concept for the discovery of not-yet-described ancient pathogens in well-preserved specimens, using de novo metagenomic assembly.

Airway microbiome dynamics and relationship to ventilator-associated infection in intubated pediatric patients

BACKGROUND

Little is known about the airway microbiome in intubated mechanically ventilated children. We sought to characterize the airway microbiome longitudinally and in association with clinical variables and possible ventilator-associated infection (VAI).

METHODS

Serial tracheal aspirate samples were prospectively obtained from mechanically ventilated subjects under 3 years old from eight pediatric intensive care units in the United States from June 2017 to July 2018. Changes in the tracheal microbiome were analyzed by sequencing bacterial 16S ribosomal RNA gene relative to subject demographics, diagnoses, clinical parameters, outcomes, antibiotic treatment, and the Ventilator-Associated InfectioN (VAIN) score.

RESULTS

A total of 221 samples from 58 patients were processed and 197 samples met the >1000 reads criteria (89%), with an average of 43,000 reads per sample. The median number of samples per subject was 3 (interquartile range [IQR]: 2-5), with a median VAIN score of 2 (IQR: 1-3). Proteobacteria was the highest observed phyla throughout the intubation period, followed by Firmicutes and Actinobacteria. Alpha diversity was negatively associated with days of intubation (p = .032) and VAIN score (p = .016). High VAIN scores were associated with a decrease of Mycobacterium obuense, and an increase of Streptococcus peroris, Porphyromonadaceae family (unclassified species), Veillonella atypica, and several other taxa. No specific pattern of microbiome composition related to clinically diagnosed VAIs was observed.

CONCLUSIONS

Our data demonstrate decreasing alpha diversity with increasing VAIN score and days of intubation. No specific microbiome pattern was associated with clinically diagnosed VAI.