Among 2179 Salmonella isolates obtained during national surveillance for salmonellosis in China from 2005 to 2013, we identified 46 non-H2S-producing strains originating from different sources. The isolates were characterized in terms of antibiotic resistance and genetic variability by pulsed-field gel electrophoresis and multilocus sequence typing. Mutation in the phs operon, which may account for the non-H2S-producing phenotype of the isolated Salmonella strains, was performed in this study. Among isolated non-H2S-producing Salmonella strains, more than 50% were recovered from diarrhea patients, of which H2S-negative S. Gallinarum, S. Typhimurium, S. Choleraesuis and S. Paratyphi A isolates constituted 76%. H2S-negative isolates exhibited a high rate of resistance to ticarcillin, ampicillin, and tetracycline, and eight of them had the multidrug resistance phenotype. Most H2S-negative Salmonella isolates had similar pulsed-field gel electrophoresis profiles and the same sequence type as H2S-positive strains, indicating a close origin, but carried mutations in the phsA gene, which may account for the non-H2S-producing phenotype. Our data indicate that multiple H2S-negative strains have emerged and persist in China, emphasizing the necessity to implement efficient surveillance measures for controlling dissemination of these atypical Salmonella strains.

Background: Intracranial infection caused by Streptococcus pyogenes is extremely rare in adults. We report a case of Streptococcus pyogenes combined with Epstein-Barr virus (EBV) infection in cerebrospinal fluid (CSF), which was diagnosed by targeted next-generation sequencing (tNGS). The findings were subsequently confirmed by capillary electrophoresis (CE) and quantitative real-time PCR (qPCR), respectively. Meanwhile, digital PCR (dPCR) detection indicated the presence of Streptococcus species DNA in the blood. Brain magnetic resonance imaging (MRI) suggested the possibility of meningitis. The patient’s condition improved significantly following combined antibacterial and antiviral therapy. Case summary: A 67-year-old female patient with a history of diabetes mellitus for over ten years presented with fever, vomiting, and impaired consciousness. CSF analysis showed significantly elevated cell count, elevated neutrophil percentage, and increased lactate dehydrogenase (LDH) levels. The tNGS result of CSF indicated Streptococcus pyogenes and EBV coinfection, meanwhile, dPCR of peripheral blood suggested the presence of Streptococcus species. The patient was therefore diagnosed with intracranial infection, sepsis, and septic shock. The antimicrobial therapy was promptly adjusted to include combined antibacterial and antiviral treatment. Following intervention, the patient’s symptoms gradually improved. Subsequent CSF analysis and tNGS testing demonstrated normalization of cell count and LDH levels, a significant decrease in the detection level of Streptococcus pyogenes , and negative detection of EBV. Conclusion: Intracranial coinfection involving Streptococcus pyogenes and EBV is exceptionally rare in adults. Early clinical manifestations are often nonspecific, yet the disease can progress rapidly, underscoring the critical importance of prompt and accurate pathogen identification. The widespread application of tNGS has significantly enhanced early diagnostic capabilities in cases of intracranial infection.