Resolving Alinity m multi-Collect media incompatibility with guanidinium-based lysis methods used for Neisseria...

False-positive Neisseria gonorrhoeae (NG) screening results require supplemental nucleic acid amplification testing for confirmation; however, Alinity m multi-Collect media (Alinity media) forms a precipitate when combined with guanidinium-based lysis buffers, interfering with nucleic acid extraction and causing Xpert CT/NG assay failures. This study evaluated a simple pre-extraction method to enable supplemental NG testing from Alinity media. A guanidine hydrochloride pre-extraction step was developed to remove precipitate prior to testing. Sixteen NG-positive urine specimens and a swab dilution series were inoculated into both Alinity media and cobas PCR media as a control. Samples were tested using Xpert CT/NG (NG2 and NG4 targets) and extracted on the MagNA Pure 96 platform for supplemental testing with ResistancePlus GC (RP-GC), targeting opa and porA. Qualitative results from Alinity media and cobas PCR media were in complete agreement, with paired quantification cycle (C_q) values showing high concordance across all targets and internal controls. RP-GC opa and porA targets demonstrated mean C_q differences of -0.45 and - 0.47, respectively, indicating a small but statistically significant earlier C_q for Alinity media (p = 0.004 and p = 0.018). Despite reaching statistical significance, these differences were less than 0.5 cycles and were not considered analytically meaningful. Xpert NG2 and NG4 targets showed negligible, non-significant C_q shifts. These findings demonstrate that the guanidine hydrochloride pre-extraction method effectively removes precipitate from Alinity media and enables reliable supplemental NG testing, with performance equivalent to cobas PCR media across both extraction-based and sample-to-answer platforms.