 Welcome back to Med Smarter where we're taking a smarter approach to preparing future physicians Today we're going to look over the gram-negative algorithm and help you answer some of those questions a little bit easier So as you can see here, this is our gram-negative algorithm First and foremost we are dealing with Gram-negative already because we've done a gram stain and the gram stain shows up with pink colonies If they were more blue or purple then we're going to be dealing with a gram-positive organism But we know that we have a gram-negative organism because the color of that organism under a gram stain is pink Let's zoom in a little bit and take a look a little closer at some of this information So we've got a gram-negative organism and we can then look at their specific structure under a microscope and Determine if we're dealing with diplococci, coxobacilli or curved rods if we see diplococci and it's aerobic we can check for maltose acid detection and basically what that is doing is we are adding a carbohydrate of maltose to the solution containing the microorganism as well as a pH indicator and if that solution turns yellow after adding that carbohydrate of maltose then We have a maltose acid detection Positive that will indicate that we are dealing with Nigeria meningidotus if we do not see that change in color from red to yellow After adding our maltose to that solution then we are dealing with Nigeria gonorrhea or moraccella If what we see under the microscope is the coxobacilli then we are dealing with one of these organisms homophilus influenza, bordotella pertussis, Pasturella brucella, Fransicilla tularenesis or Actinobacter bumani. If we see curved rods, we know that they're going to be oxidase positive We'll discuss oxidase positive here in just a minute when we get down to the bacilli. So then we can Determine what specific microorganism we're dealing with based upon how they grow So if it grows under 42 degrees Celsius conditions, then we're dealing with Campylobacter geudii If it grows in an alkaline median, then we're talking about vibrio cholera and if it produces urease This is helicobacter pylori Finally, let's look at our bacilli. So under the microscope We've determined that we have bacilli present in our test And we're going to check its lactose fermentation As with our maltose acid detection the lactose fermentation adds a lactose carbohydrate as the carbon source along with a phenol red indicator and if that microorganism Utilizes that lactose for energy Then it will turn a yellow color because this pH is going down So if we have yellow indication We know that we have lactose fermenters and it can and occur fast or slow the speed of that Lactose fermentation will determine what we're dealing with E. Coli club C. Ella and intrabacter are fast lactose fermenters Citrobacter and seracea are slow lactose fermenters If we do not have any lactose fermentation, then we can check their oxidase status to determine oxidase This is going to check for a terminal enzyme in the aerobic respiration called cytochrome C oxidase also known as cytochrome A3 And if it produces this Then it will give us a reaction on our Auger plate so we are going to check for oxidase and if we do see oxidase Positive and then we're dealing with pseudomonas if we are oxidase negative We're going to check its Hydrogen sulfide production on our TSI auger if it does produce hydrogen sulfide Then we're talking about salmonella and proteus or shigella and your sinia when it does not Produce hydrogen sulfide once again come back later and we will discuss more of these Microbacteria in further detail if you found this material helpful for your studying Please like and consider subscribing to the channel also share this video so that more people can benefit from it like you have