Streptococcus dysgalactiae subsp. equisimilis (SDSE) typically expresses Lancefield group C or G antigens, whereas group A isolates are very uncommon. We report a clinical case of bacteremia caused by a Lancefield group A SDSE isolate with its genomic characteristics. A 73-year-old man was hospitalized for acute decompensated heart failure. His blood cultures yielded Lancefield group A β-hemolytic streptococcus, initially raising clinical suspicion of Streptococcus pyogenes bacteremia. However, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identified the isolate as S. dysgalactiae, for which the patient was successfully treated with a 14-day course of antimicrobial therapy. Later, we performed a whole-genome sequencing that confirmed the isolate as SDSE, showing 99.21% average nucleotide identity to a deposited strain of SDSE SS1722. The isolate was assigned to sequence type 177 and emm subtype stG652.0. All 12 group A carbohydrate biosynthesis genes, gacA-gacL, were detected on a single scaffold in the same order as in S. pyogenes MGAS5005. The genes showed 77.1-99.9% nucleotide identity to the corresponding MGAS5005 sequences; notably, gacF-gacL showed identities of 99.4-99.9%, whereas gacA-gacE showed lower identities of 77.1-91.5%. Virulence-associated gene profiling detected emm, spg, ska, slo, sagA, scpA, and speG, whereas speA, speC, speL, speM, and ssa were not detected. This case demonstrates that Lancefield group A reactivity in β-hemolytic streptococci does not necessarily indicate S. pyogenes. When Lancefield grouping and species identification are discordant, genomic analysis can clarify both the taxonomic identity of the isolate and the genetic basis of its antigenic phenotype.

Fungal endocarditis (FE) caused by Exophiala dermatitidis (E. dermatitidis) is extremely rare, and optimal management remains unclear because most reported cases have been treated with combined surgical and antifungal therapy. We describe a 76-year-old man with catheter-related bloodstream infection complicated by tricuspid valve FE due to E. dermatitidis. The patient had a history of repeated catheter-related infections and was considered a poor candidate for surgery because of his general condition. After prompt removal of the implanted central venous port, he received sequential antifungal therapy with micafungin, liposomal amphotericin B, voriconazole, and long-term itraconazole suppression. Blood cultures cleared, and serial transthoracic echocardiography showed no clinically significant progression of the tricuspid vegetation. At more than 590 days after diagnosis, he remains alive without recurrent fungemia while receiving oral itraconazole. This case suggests that nonsurgical management with source control, systemic antifungal therapy guided by clinical response and antifungal susceptibility information, and long-term azole suppression may be a feasible option for selected patients with E. dermatitidis FE when surgery is not possible.

Listeria monocytogenes is a major cause of invasive infections in individuals with impaired cell-mediated immunity. Recently, the combination of pembrolizumab with concurrent chemoradiotherapy has been established as the standard treatment for high-risk, locally advanced cervical cancer. Nevertheless, characterization of severe infections that occur during this treatment regimen remains inadequate. Herein, we report a case of L. monocytogenes meningitis that occurred during pembrolizumab-based chemoradiotherapy for cervical cancer. A 45-year-old woman with no underlying medical conditions was diagnosed with p16-positive cervical squamous cell carcinoma, involving the pelvic, para-aortic and left supraclavicular lymph nodes. The patient received concurrent chemoradiotherapy with weekly cisplatin and pembrolizumab every 3 weeks. On day 44, after receiving 50.4 Gy of external beam radiotherapy, she developed febrile neutropenia with a temperature of 40.1 °C, white blood cell count of 600/μL, absolute neutrophil count of 408/μL, and worsening diarrhea. She was treated with cefepime, and blood and urine cultures were negative. Immune-related adverse events, including endocrine disorders, were considered unlikely. After clinical improvement, she completed the concurrent chemoradiotherapy phase. On day 73, the patient presented with headache, nausea, and vomiting. Cerebrospinal fluid examination revealed neutrophilic pleocytosis, elevated protein levels, and hypoglycorrhachia. Blood and cerebrospinal fluid cultures yielded L. monocytogenes. She was treated with ampicillin and gentamicin for 3 weeks and recovered. Thus, fever during pembrolizumab-based chemoradiotherapy should not be solely attributed to immune-related adverse events. Severe infections, including Listeria meningitis, should be considered when fever or neurological symptoms occur, particularly in patients with myelosuppression, immune dysregulation, or gastrointestinal toxicity.

Anaerobic bacteria are uncommon causes of bacterial meningitis. We report a rare case of polymicrobial anaerobic meningitis with ventriculitis involving Slackia exigua and Solobacterium moorei, both oral anaerobes. A 41-year-old woman presented with headache, vomiting, and impaired consciousness. Cerebrospinal fluid analysis was consistent with bacterial meningitis, and cultures yielded S. exigua and S. moorei, identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, with S. exigua confirmed by 16S rRNA gene sequencing. Blood cultures showed polymicrobial bacteremia, including S. exigua, Streptococcus anginosus, and Desulfovibrio falkowii. The identification of D. falkowii was performed using 16S rRNA gene sequencing and corroborated by whole-genome sequencing. Untreated dental caries, periodontitis, and sinusitis were considered potential portals of entry. The patient responded favorably to continued antimicrobial therapy with ampicillin/sulbactam and metronidazole. This case highlights the clinical relevance of rare oral anaerobes in central nervous system infections. It underscores the polymicrobial nature of anaerobic meningitis and illustrates the potential value of combining conventional culture, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and molecular methods in identifying uncommon pathogens.

Recurrent tuberculosis is traditionally classified as exogenous reinfection or endogenous reactivation. We previously proposed "collateral reactivation," in which distinct Mycobacterium tuberculosis subclones derived from a hypothetical original clone are involved in separate disease episodes, in contrast to traditional endogenous ("direct-descent") reactivation. To explore whether collateral reactivation occurs beyond the single case we previously reported, we reanalyzed publicly available whole-genome sequencing data from 123 recurrent tuberculosis cases. After curation, 119 cases (pairwise single-nucleotide variant [SNV] distance, 0-18) were classified as cases of collateral or direct-descent reactivation. In 21 cases (17.6%), a hypothetical original clone could be inferred, and these cases were classified as collateral reactivation. These cases showed a higher rate of SNVs/genome/year (median 3 vs. 0.4, p < 0.0001) and a higher proportion of drug resistance-associated SNVs (23.8% vs. 4.1%, p = 0.009) than direct-descent reactivation cases. These observations support the view that collateral reactivation is not restricted to the single case we previously reported, although mixed infection or exogenous reinfection caused by closely related strains cannot be excluded as alternative explanations. To determine whether collateral reactivation should be recognized as a concept distinct from direct-descent reactivation, future studies integrating whole-genome sequencing of single colonies, lesion-specific sampling, longitudinal sampling, deep sequencing, imaging, clinical follow-up, and epidemiological exposure information will be required.

The Long COVID Burden Index (LCBI) is an 11-item patient-reported outcome measure developed to assess the burden of long COVID symptoms on daily life. Although its cross-sectional validity and internal consistency have been demonstrated, its test-retest reliability, measurement error, and minimal important change (MIC) have not yet been evaluated. We conducted a longitudinal postal survey among adults with a history of COVID-19 hospitalization. The LCBI was administered at the initial survey, 2-week follow-up, and 3-month follow-up. Test-retest reliability was assessed among participants who completed the initial and 2-week surveys and reported no change on a 7-point global rating of change question. Measurement error was evaluated using the standard error of measurement (SEM) and the smallest detectable change (SDC) was calculated. The MIC was estimated at 3 months by using anchor-based methods: the mean change method, receiver operating characteristic curve analysis, and predictive modeling. Among 1031 potential participants, 301 provided valid responses at the initial survey, 258 at the 2-week follow-up, and 208 at the 3-months follow-up. The intraclass correlation coefficient for the LCBI total score was 0.78 (95% confidence interval, 0.72-0.83). The SEM and SDC were 3.26 and 9.04 points, respectively. The MIC estimates ranged from 1.73 to 2.91 points across methods. The LCBI showed good test-retest reliability. A reduction of approximately 2-3 points may represent a minimal important improvement. However, this change is below the SDC and does not provide definitive evidence of change beyond measurement error.