the invention relates to a fragment of the genomic dna of streptococcus pneumoniae , a probe capable of specifically hybridizing with the genomic dna of screptococcus pneumoniae , a specific primer for the amplification , by polymerization , of the genomic dna , a reagent and a method which are used with the probe and , optionally , the primer , for specifically detecting streptococcus pneumoniae in a biological sample . the probe of the invention is a nucleotide sequence having at least 70 % homology with at least a portion of a consensus sequence of the genomic dna of streptococcus pneumoniae , this consensus sequence being chosen from the nucleotide sequences seq id no 2 , seq id no 3 , seq id no 4 , which are identified in the description , and their respective complementary sequences .