Patterns of Gardnerella vaginalis Co-Detection with Ureaplasma urealyticum and Ureaplasma parvum in Adult Urogenital Molecular Testing in the Republic of Korea, 2018–2022

Multiplex PCR assays report Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP) separately, but the results are often combined as “Ureaplasma positive.” We compared Gardnerella vaginalis (GV) co-detection in UU-only and UP-only adult specimen accession records and examined variation by sex and age. This retrospective study included 176,855 urogenital records from a Korean reference laboratory (2018–2022). The primary comparison (N = 46,319) used modified Poisson regression adjusted for sex, age group, specimen type, and collection year. GV co-detection ranged from 15.7% in UU−/UP− records to 86.0% in UU+/UP+ records. For UU−/UP+ versus UU+/UP− records, the adjusted prevalence ratio (aPR) was 1.06 (95% CI, 1.04–1.08). Sex-specific aPRs were 0.93 (0.91–0.95) in women and 1.13 (1.10–1.15) in men (p for interaction < 0.001); the sex-specific directions were reproduced in a urine-only analysis.. Age-related differences were nonmonotonic and exploratory. The overall association was small, and the use of different multiplex panels for UU and UP/GV means that cross-panel analytical differences could have contributed to, or potentially accounted for, the observed difference. These findings should therefore be interpreted as descriptive laboratory co-detection patterns rather than evidence of a biological interaction or clinically meaningful species-specific difference..