Improved Diagnostics Help to Identify Clinical Features and Biomarkers That Predict Mycoplasma pneumoniae Community-acquired Pneumonia in Children

Meyer Sauteur, Patrick M; Krautter, Selina; Ambroggio, Lilliam; Seiler, Michelle; Paioni, Paolo; Relly, Christa; Capaul, Riccarda; Kellenberger, Christian; Haas, Thorsten; Gysin, Claudine; Bachmann, Lucas M; van Rossum, Annemarie M C; Berger, Christoph

was even true for PCT and CRP of Mp-positive CAP in comparison to viral CAP (RSV) as a subgroup of Mp-negative CAP. Similar trends have been observed in previous CAP studies for CRP, WBC count, and ANC [23, [39] [40] [41] [42] [43] , and recently for PCT with median levels from 0.05 to 0.19 μg/L in CAP considered to be caused by Mp [39] [40] [41] 44] . A study with conflicting results suggesting higher PCT levels associated with Mp may be hampered by diagnostics [45] . A PCT cutoff of <0.25 μg/L reached the best discriminatory power in differentiating Mp-positive from Mp-negative children with CAP, which is supported by previous studies [39] [40] [41] 44] . Only 1 Mp-positive patient had a PCT level of 0.55 μg/L and was above this cutoff. Our study has several limitations. First, though sampling was performed in a relevant population of clinical CAP [9] , the study population is small and represents a convenience sample from an observational study, and we cannot rule out that unintended selection occurred. However, even though the sample size is small for prediction, the scope of this study was to describe risk factors for Mp infection. Second, mild cases may not have been referred to our tertiary center. Third, the study enrolled children from 3 to 18 years of age to reduce the probability of viral infection [9] . However, younger children with Mp infection may have, more likely, other RTIs than CAP [43] .