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[S. typhimurium strains which are H2S negative in TSI medium]
Abstract:
During an epidemic in the premature ward of Ankara Pediatric Hospital which lasted for almost 25 days, 15 cases were diagnosed and H2S (TSI medium) negative S. typhimurium strains were isolated 23 times on the specimens obtained from these patients. Specimens consisted of mainly stools but two were blood samples, one was a lung aspirate and two were pathologic materials obtained from the elbow and hip joints of the same patient. When these strains were transferred to Braun-Ozek B Medium, they were able to produce H2S which was detected because of the strong blackening on the lead acetate paper. Component replacement studies were performed to show which were necessary for the production of H2S in this second media. According to the results of this studies Pepton witte + meat extract broth + Na2S2O3 . 5H2O were found essential for the production of H2S in Braun-Ozek B. Medium. When this medium was prepared with the incorporation of ferrous ammonium sulfate instead of Na2S2O3, 5H2O, the production of H2S decreased and delayed.
Insights
During an epidemic, Salmonella typhimurium strains initially negative for hydrogen sulfide (H2S) production were identified. Supplementing a specific medium with Pepton witte, meat extract broth, and sodium thiosulfate restored H2S production.
Area of Science:
- Microbiology
- Bacteriology
- Clinical Diagnostics
Context:
- An epidemic of Salmonella typhimurium occurred in a premature ward.
- 15 cases were diagnosed, with strains isolated from various clinical specimens including stool, blood, and joint material.
- The isolated S. typhimurium strains were initially H2S (TSI medium) negative.
Purpose:
- To investigate the H2S production capabilities of S. typhimurium strains isolated during an epidemic.
- To identify the essential components for H2S production in a modified medium (Braun-Ozek B Medium).
- To compare the efficacy of different sulfur sources for H2S production.
Summary:
- Salmonella typhimurium strains isolated from an epidemic were found to be H2S negative in standard TSI medium.
- When transferred to Braun-Ozek B Medium, these strains produced H2S, indicated by blackening on lead acetate paper.
- Component replacement studies revealed that Pepton witte + meat extract broth + Na2S2O3 . 5H2O were essential for H2S production in Braun-Ozek B Medium.
- Replacing Na2S2O3 . 5H2O with ferrous ammonium sulfate reduced and delayed H2S production.
Impact:
- This research identifies key nutritional and chemical factors required for H2S production by S. typhimurium.
- The findings contribute to understanding bacterial metabolism and optimizing diagnostic media for accurate Salmonella identification.
- This knowledge can aid in the development of more sensitive and specific laboratory tests for detecting S. typhimurium during outbreaks.