|Description:||After 24 hours, this inoculated xylose-lysine-deoxycholate (XLD) agar culture plate cultivated colonial growth of Gram-negative, rod-shaped and facultatively anaerobic Serratia marcescens bacteria.|
Xylose Lyseine (XL) agar is used when trying to culture and isolate Gram-negative enteric bacilli, i.e., rods. When XL agar is supplemented with sodium thiosulfate, ferric ammonium citrate, and sodium deoxycholate, it is then termed XLD agar, and is then an even more selective medium than XL alone. The presence of any black colored area indicates the deposition of hydrogen sulfide, (H2S) under alkaline conditions. S. marcescens is an opportunistic pathogen, which means that it is usually not a cause of disease, however, under immunocompromised circumstances this bacterium can be found the culprit responsible for nosocomial infections such as endocarditis and pneumonia.