this is a genusspecific pcr, with primers for the S. aureus in lane 2 and 3 (2 being the negative control that is positive). In lane 4 and 5 are the used primers for S. epidermidis. Lane 4 confirms that the bacteria is the S. epidermidis, but there is also a primerdimer. Does this make my result not reliable?
primer dimer does not invalidate a positive amplification of your template .The amplified band is fine. The problem with primer dimer is tha tif it is too strong then it may remove all of the primer from the reaction mixture and the proper amplimer could then be so weak that it looks negative even though the sample may contain your target. You should know that ethidium bromide binds between the strands of DNA to give fluorescence which depends on the length of the dna so primer dimer binds very little ETBR so if you can see primer dimer at all then there is a huge amount of it. You should use either better primers, less primer ar best of all a hot start dna polymerase to get rid of the primer dimer
the result is reliable but if you are going to sequence the product then you must get rid of the primer dimer or the sequencing will be very weak as you will end up sequencing only the dimer
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