| Summary: | The quality control of culture media used for <i>Legionella</i> spp. isolation and enumeration is paramount to achieve a satisfactory degree of comparability among water testing results from different laboratories. Here, we report on a comparative assessment of the sensitivity and selectivity of MWY and BCYEα media supplied by two different manufacturers (i.e., Xebios Diagnostics GmbH and Oxoid Ltd) for the detection of <i>Legionella</i> spp. from environmental water samples. Even though our analysis showed an excellent agreement between the recovery rates of the four media tested (90.5%), the quantitative recovery of <i>Legionella</i> spp. colonies using Xebios media was significantly greater than that achieved by Oxoid media (<i>P</i> = 0.0054). Furthermore, the sensitivity of detection was significantly higher when samples were plated on MWY <sup>Xebios</sup> agar (<i>P</i><i> </i>= 0.0442), while the selectivity of MWY appeared to be the same regardless of the manufacturer. Furthermore, MWY<sup>Xebios</sup> agar favored the growth of much larger colonies compared to those observed on MWY<sup>Oxoid</sup> agar. Finally, MWY<sup>Xebios</sup> medium enhanced the recovery of non-<i>pneumophila Legionella</i> species. Collectively, our findings demonstrate that quality control is crucial to ensure high selectivity and sensitivity of the culture media used for the detection and enumeration of <i>Legionella </i>spp. from environmental water resources. As water remediation measures strictly depend on <i>Legionella</i> spp. recovery, culture protocol standardization, as well as quality control of the culture media, is essential to achieve intra- and interlaboratory reproducibility and accuracy.
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