Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates ofM.intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1–2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and late (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs ofM.intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover,in vitrodata showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells uponM.intracellulareinfection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonaryM.intracellulareinfection in mice, at least in part through MMP-3 production.

Upon MAC stimulation, the production of IL-1 family cytokines and IL-10 by PBMCs of NTMPD patients was attenuated compared with that of healthy household contacts. Upon MAC stimulation, the expression of TLR2 and TWIK2 (one of the two-pore domain K+ channels) was attenuated in PBMCs of NTMPD patients compared with that of healthy household contacts.

The incidence of mammary gland tumors in dogs is a significant issue, characterized by notable rates of malignancy, recurrence, and disease burden. However, the lack of comprehensive information and correlated studies has presented challenges in establishing an effective surgical treatment strategy. In this study, a cohort of 95 dogs diagnosed with mammary tumors underwent evaluation using various surgical methods, medications, ovariohysterectomy, and assessments of margin completeness to analyze clinical outcomes. Significant clinical outcomes were observed following radical mastectomy and conservative surgeries, irrespective of TNM stages and histopathological grade of malignancy. Complete excision demonstrated significantly improved survival time and disease-free interval compared to incomplete excision. It is noted that complete surgical excision provides benefits, even in cases where lymphatic invasion is present. However, further investigations are necessary to validate the clinical results and mitigate side effects from radical mastectomy. Despite postoperative complications, several studies continue to advocate for more radical mastectomies due to their favorable risk-benefit ratio. Moreover, advanced inpatient treatments can now effectively manage or mitigate many of these complications. This study emphasizes the critical role of surgical proficiency and postoperative medication in treating malignant mammary tumors in dogs, and it provides insights that may contribute to the development of more effective treatment strategies for this condition.

Seung-Hyun Kim, Dae Sung Yoo, Dae-Hun Park, Seung-Sik Cho, Seungjo Park, Bock-Gie Jung, Sang-Ik Park, Chun-Sik Bae. J Vet Clin 2024;41:359-69. https://doi.org/10.17555/jvc.2024.41.6.359

Migratory birds travel long distances and interact with diverse environments, making them potential reservoirs and disseminators of antimicrobial-resistant bacteria. This study investigated the species distribution of migratory birds, bacterial isolates from bird internal organs, and the corresponding antimicrobial resistance (AMR) profiles in South Korea. A total of 35 bird carcasses representing 20 species were collected from five major stopover sites on the Sinan-gun islands along the East Asian–Australasian Flyway. More than half of the sampled birds belonged to the genus Emberiza, reflecting the prevalence of small migratory passerines in coastal habitats. From these carcasses, 54 bacterial isolates belonging to 24 species were identified, including Enterococcus spp., coliforms such as Enterobacter spp. and Escherichia coli, and opportunistic pathogens including Bacillus spp., Staphylococcus spp., and Serratia spp. Antimicrobial susceptibility testing revealed that 18 isolates (33.3%) were multidrug-resistant (MDR). Enterococcus isolates displayed high resistance to tigecycline and daptomycin, and two vancomycin-resistant strains were identified. Coliform isolates were resistant to third- and fourth-generation cephalosporins, carbapenems, and colistin. The two E. coli strains exhibited concurrent carbapenem–colistin resistance, posing a significant public health concern. These findings provide the first organ-level AMR dataset for migratory birds in South Korea and highlight the potential role of small passerines as ecological sentinels of environmental contamination. The detection of MDR strains underscores the need to integrate wildlife surveillance into One Health strategies for AMR monitoring.