A 42-year-old man, a coal miner with a history of pulmonary tuberculosis, dust exposure, and suspected pneumoconiosis, presented with cough, purulent sputum, and intermittent fever for more than 1 month. Routine sputum bacterial and fungal cultures, as well as acid-fast bacilli smears, were persistently negative. Chest computed tomography revealed markedly distorted bilateral lung architecture with patchy and nodular opacities, multiple irregular cavitary lesions, emphysema, pulmonary bullae, and mediastinal lymphadenopathy. To obtain a definitive diagnosis, a bronchoscopy was safely performed under strict asepsis and painless anesthesia. The procedure showed inflammatory bronchial changes and narrowing of the right upper lobe posterior and dorsal segmental bronchi due to external compression. Targeted next-generation sequencing (tNGS) of the bronchoalveolar lavage fluid on the MGI VisionSeq 1000 platform detected Mycobacterium avium complex (349 sequence reads, 53.4% relative abundance). The patient's condition improved rapidly following a targeted multidrug regimen (clarithromycin, rifampicin, ethambutol, and amikacin) combined with supportive pneumoconiosis care. This case highlights the vital role of tNGS in differentiating nontuberculous mycobacterial disease from recurrent tuberculosis in patients with complex structural lung damage, enabling timely and precise intervention.

Nocardiosis is an uncommon infection that can cause severe damage or be life-threatening. However, the epidemiology and strain distribution of nocardiosis in China remain poorly characterized. In this study, a comprehensive literature search was conducted using the keyword "('Nocardia' OR 'Nocardiosis') AND ('China' OR 'Chinese')" in PubMed and Web of Science, and "(Nuokajun) OR (Nukajun)" in the China National Knowledge Infrastructure (CNKI) database. All published cases of nocardiosis between April 1, 1990, and September 13, 2024, were included. Geographic analysis identified a concentration of cases in eastern coastal China. The mean patient age was 52.6 ± 17.4 years, with a male predominance (61.0%) and the highest burden in the 50-59 age group (24.4%). The primary infection sites were the lungs (69.9%), skin (30.3%), and brain/central nervous system (CNS) (19.3%). Disseminated infections accounted for 29.0% of all cases and were associated with a markedly higher mortality rate (16.1%) compared with the overall rate (9.0%), underscoring the importance of early diagnosis and treatment. The predominant species were Nocardia farcinica, Nocardia cyriacigeorgica, and Nocardia brasiliensis. Most isolates remained highly susceptible to trimethoprim-sulfamethoxazole, amikacin, and linezolid. This study has established a national epidemiological pattern of Nocardia infections and strain distribution in China. The elevated risk and mortality associated with disseminated infections warrant vigilance. This underscores the need for heightened clinical awareness of Nocardia infections and ensure timely screening and treatment.

Carbapenems, often regarded as the last line of defense in treatment of urinary tract infections and urosepsis caused by Escherichia coli, are under pressure from emerging resistance. Thus, it is necessary to investigate carbapenem-sparing agents to mitigate the dissemination of carbapenem resistance. In this study, we aimed to evaluate the efficacy of ceftazidime/avibactam plus amikacin combination therapy against two ceftazidime/avibactam-resistant E. coli clinical isolates harboring IMP-4 carbapenemase (CTAP #226 and CTAP #233). To achieve this, we used a hollow fiber infection model (HFIM) with clinically relevant regimens of amikacin (15 mg/kg q24h) and ceftazidime/avibactam (2 g ceftazidime/0.5 g avibactam q8h), which were administered to the HFIM either alone or in combination over a 7-day treatment course. Initial inoculum was ~1 × 10[7] CFU/mL. Both amikacin and ceftazidime/avibactam monotherapies resulted in bacterial killing (~4 log10 and ~3 log10, respectively) within the first 8 h; however, regrowth surpassing the baseline was observed over the following 7 days. Conversely, combination therapy resulted in bacterial killing to <the limit of quantification (10[2] CFU/mL) within the first 48 h, which was sustained for the entirety of the experiment. This study showed that the combination of amikacin and ceftazidime/avibactam was superior to both monotherapies and therefore presents a promising carbapenem-sparing option for the treatment of ceftazidime/avibactam-resistant E. coli. Further clinical studies are required to assess the suitability for use in vivo.

A 76-year-old man with pancreatic cancer was readmitted in septic shock due to a recrudescent liver abscess, previously treated with cefepime for four weeks. While only Klebsiella pneumoniae (KP) without acquired resistance was initially isolated from liver abscess cultures, both carbapenem-susceptible KP (CSKP) and carbapenem-resistant KP (CRKP) were identified from liver abscess and blood cultures during this admission. Whole-genome sequencing revealed that CRKP had a chromosome of ST420 containing yersiniabactin genes, blaSHV-75, emrD, fosA, and oqxAB, plus two plasmids: IncX3-type carrying blaKPC-2 and blaSHV-11, and IncHI1B-type carrying aerobactin genes, salmochelin genes, and rmpA. CSKP was ST889 with KL54 capsular type, harboring an IncFIB/IncFII-type plasmid carrying blaCTX-M-15, and multiple additional resistance determinants. The patient died despite 11 days of meropenem, amikacin, and colistin combination therapy. This is the first report of a hypervirulent CRKP of ST420 carrying blaKPC-2.

In October 2025, an outbreak occurred among farmed Chinese rice-field eels (Monopterus albus) in Jiangxi, China. A Nocardia seriolae strain designated JXMa251025, which has not been previously documented in Chinese rice-field eels, was isolated from moribund fish exhibiting multiple white nodules of various sizes in visceral tissues. Histopathological examination revealed multi-organ damage, including necrosis of liver cells, granulomatous inflammation with hemorrhage in visceral organs, and necrosis of renal glomeruli and tubules accompanied by vascular congestion. Artificial infection trials confirmed that strain JXMa251025 reproduced clinical signs consistent with those observed in the natural outbreak. Infection experiments resulted in 100% mortality in high-concentration challenge groups, with a median lethal dose (LD50) of 9.76 × 10[5] CFU/mL, indicating high virulence. Whole-genome sequencing revealed a circular chromosome of 8,295,032 bp with a GC content of 68.10%. The genome contains 66 tRNA genes and four copies each of the 23S, 16S, and 5S rRNA genes. Phylogenomic analysis placed strain JXMa251025 within a clade of Nocardia seriolae strains with approximately 99% bootstrap support, confirming its identification as Nocardia seriolae. Further genomic screening identified 253 potential virulence genes associated with nutrient metabolism, regulatory systems, immune modulation, effector delivery, and exotoxin production. Antibiotic susceptibility testing showed that strain JXMa251025 was sensitive to seven antibiotics: ciprofloxacin, neomycin, enrofloxacin, florfenicol, gentamicin, amikacin, and doxycycline. This study represents the first report of Nocardia seriolae infecting Chinesse rice-field eels, providing useful descriptive information for disease diagnosis and reference.

Background Pulp necrosis is a prevalent complication following dental caries in primary dentition. Certain bacteria exhibit increased adaptability to adverse conditions and possess virulence factors that enable more effective colonization of dental tissues. The invasion of the root canal system (RCS) by pathogenic microorganisms, compounded by the rising concern of antimicrobial resistance (AMR), emphasizes the necessity for a culture-driven and evidence-based approach to antibiotic selection in pediatric endodontics, wherein the therapeutic efficacy of root canal treatment is inherently dependent on the comprehensive elimination of endodontic microbiota. Aim To isolate, identify, and analyze the antimicrobial susceptibility and resistance profiles of microorganisms associated with endodontic infections in the deciduous teeth of children undergoing pulp therapy. Materials and methods One hundred systemically healthy children aged four to nine years with carious teeth and without direct endodontic exposure were enrolled following Strengthening the Reporting of Observational studies in Epidemiology (STROBE) guidelines at the Department of Pediatric and Preventive Dentistry, University College of Medical Sciences (UCMS) & Guru Teg Bahadur Hospital (GTBH), Delhi, India. Root canal samples from infected or necrotic primary teeth were aseptically collected and cultured on blood, chocolate, and MacConkey agar. Bacterial isolates were identified via Gram staining and standard biochemical assays. Statistical evaluation was conducted using IBM SPSS Statistics for Windows, Version 21 (Released 2012; IBM Corp., Armonk, New York, United States). Results Bacterial growth was detected in 68 samples (68%), predominantly involving Gram-positive cocci (n=48; 48%). Enterococcus faecalis (n=25; 25%) was the most common isolate, followed by Staphylococcus aureus (n=17; 17%) and a smaller proportion of Gram-negative bacilli, including Enterobacter cloacae, Escherichia coli, and Klebsiella pneumoniae. All isolates showed complete sensitivity to vancomycin, teicoplanin, linezolid, amikacin, and imipenem, while variable resistance to macrolides, clindamycin, fluoroquinolones, and β-lactams was observed. No extended-spectrum β-lactamase (ESBL) or carbapenem-resistant strains were identified. Conclusion Enterococcus faecalis remains the predominant pathogen in pediatric endodontic infections, with its increasing multidrug resistance presenting significant therapeutic challenges. Nevertheless, β-lactam and glycopeptide antibiotics continue to demonstrate reliable clinical efficacy. These findings highlight the importance of culture-guided therapy and rational antimicrobial stewardship in pediatric dental practice.