Provided herein is a nucleotide cassette comprising an inducible promoter, a nucleotide sequence that corresponds to at least one single stranded RNA diagnostic target, a nucleotide sequence that encodes artemin, a molecular switch and a nucleotide sequence that encodes a DNAse enzyme and is under control of the molecular switch, wherein the single stranded RNA diagnostic target is a sequence detected by a molecular diagnostic assay. In some embodiments the nucleotide cassette can be used to obtain an RNA expression product. Also provided are vectors and cells comprising the nucleotide cassette or the RNA expression product thereof. The nucleotide cassette can further be used to obtain a diagnostic control composition comprising a non-pathogenic recombinant bacterium having a modified genetic content comprising the nucleotide cassette and to methods of producing such recombinant bacteria.