Longitudinal cerebrospinal fluid PCR archives may show apparent age patterns shaped jointly by underlying disease processes and testing architecture. We examined how apparent viral detection patterns varied with denominator choice, target availability, and reconstructed testing configurations among patients tested at a Korean tertiary-care hospital from 2006 to 2026. Clinical diagnoses and adjudication were unavailable, and workflows were reconstructed from reporting configurations rather than definitive platform identifiers. The archive contained 30,481 target-level results from 5353 patient-date episodes in 4560 patients. We summarized per-target positivity, viral-positive composition, and contextual pooled target-level positivity. Human herpesvirus-6 target-level positivity peaked at 31.9% (272/854) at age 1–4 years and comprised 75.8% (91/120) of infant and 84.0% (272/324) of 1–4-year viral-positive detections. However, HHV-6 was represented in 79.9% and 96.1% of episodes in these groups, whereas enterovirus was represented in only 14.4% and 3.9%. VZV was the most frequently detected adult viral target in the full archive, although rankings varied by period. Apparent age patterns were therefore conditioned by target availability, denominator choice, and evolving workflows and should not be interpreted as clinically adjudicated CNS infection epidemiology.

Urogenital multiplex polymerase chain reaction (PCR) panels report Mycoplasma genitalium (MG) and Mycoplasma hominis (MH) similarly despite different clinical significance. We retrospectively analyzed 176,855 adult specimen-level laboratory records (2018–2022). MG and MH were compared using modified Poisson regression and a year-adjusted stacked interaction model. MG was detected in 4215 records (2.38%) and MH in 8024 (4.54%). MG prevalence fell from 4.48% (95% confidence interval (CI), 4.30–4.68) at 18–29 years to 0.21% (0.16–0.27) at ≥60 years, whereas MH fell from 5.70% to 2.39%. Female sex was associated with lower MG (adjusted prevalence ratio [aPR], 0.32) and higher MH (1.44). Age and sex gradients differed significantly (interaction PRs, 1.519 and 4.653; both p < 0.001), whereas no specimen-type interaction reached significance (all p ≥ 0.19). No other target was positive in 52.1% of MG-positive versus 54.5% of MG-negative records, but in 4.9% of MH-positive versus 55.7% of MH-negative records. MH co-detection was strongest with Gardnerella vaginalis (aPR, 9.94), Ureaplasma urealyticum (6.12), and Trichomonas vaginalis (5.48). These profiles support target-specific reporting. Cross-panel analytical differences cannot be excluded because MG and MH were measured on different panels.