Methods: A convenience sample of Mp positive PCR identified by our laboratory-developed assay, obtained from both inpatient and outpatient settings, were selected. These were then cultured using Remel’s SP4 glucose broth and then incubated at 35°C until isolates grew, or for a maximum of 4 weeks. All samples that yield positive cultures were then sequenced for the domain V of the 23S rRNA (nucleotide 1937-2154, accession no. X68422) using Sanger methods and sequences were compared with corresponding region of wildtype reference strain (ATCC 15322).
Results: For the period of October 2015-March 2017, culture was attempted in 433 PCR-positive samples, and 347 (80%) yield an isolate. Sequencing was performed in those 347 samples and was successful in 334 (96%). A macrolide resistance mutation was detected in 10 samples (3%). From the 10 mutations detected, 7 (70%) were the A2063G mutation, and 3 (30%) were A2064G. We also detected a deletion in A2065 of unknown significance in 3 samples (0.9%).
Conclusion: In this pediatric population, culture was successful in 80% of PCR positive samples, thus providing isolates for sequencing to be able to assess our local resistance. Our overall Mp resistance was 3%, suggesting that empiric treatment with macrolides is still appropriate in Central Ohio. Additional studies are needed to correlate the presence of these resistance mutations with phenotypic susceptibility testing and clinical outcomes.
M. Lanata Piazzon,
K. Everhart, None
O. Ramilo, Abbvie: Board Member , Consulting fee
Regeneron: Board Member , Consulting fee
Janssen: Board Member and Investigator , Consulting fee and Research grant
NIH: Grant Investigator , Research grant
A. Leber, BioFIre Diagnostics: Research Contractor and Scientific Advisor , Research support , Speaker honorarium and Travel expenses