A Christie, Atkins, and Munch-Peterson (CAMP) test is a way for microbiologists to test for the presence of a particular type of bacteria in a sample called group B streptococcus. It is a visual test that involves a growth medium with a blood ingredient, a known type of bacteria, and the sample. The blood breaks down in a distinctive way, leaving areas of growth medium that appear translucent, because if group B streptococci are present in the sample, they produce a protein called CAMP factor that interacts with the other type of bacteria involved.
This test is named after the scientists who first discovered it in 1944 and thus bears their names, or more commonly, their initials. Historically, microbiologists noted that different types of bacteria grew on different forms of media in distinctive ways, because individual bacterial species generally specialize in using certain nutrients and living in certain conditions, although some are more susceptible to other environments. changing. In the case of the CAMP test medium, this is a Petri dish filled with a solid agar mixture containing a variety of nutrients and blood from a cow or sheep.
An analyst streaks a line of bacteria in a line down through the center of the plate. This bacterium is a known strain of Staphylococcus aureus that labs can buy that only contains cells from that particular strain and no other bacteria. These bacteria can break down the blood cells of sheep or cattle for use as food. After time in an incubator that keeps the bacteria warm and helps them grow, this strain of S. aureus produces a translucency under the area where the analyst placed the bacteria at the beginning of the incubation. This visible translucency is due to a protein called beta hemolysin produced by bacteria that breaks down the cells and turns the cells red.
When CAMP factor, which is a protein produced by group B streptococcus, comes into contact with beta hemolysin, the effect of both together creates more translucent areas than would otherwise be the case. The basis of the CAMP test is that when an analyst scratches a small line on a sample potentially containing Group B streptococcus, at right angles to the center line of S. aureus , but not touching the center line, then any CAMP factors present make a distinctively shaped zone of translucency. A positive CAMP test shows an arrow-shaped area of translucency at the end of the second horizontal line.
This represents the area where beta hemolysin and CAMP factor overlap, and it has more of an effect on the breakdown of blood cells than either protein would individually. In addition to research purposes, the reason for performing the CAMP test may be to identify the presence of group B streptococcus in a sick person, as this group of bacteria are important human pathogens. Variations on the CAMP test include a system to check for the presence of a certain strain of listeria and another test for the presence of a particular type of Clostridium .