ABSTRACT Introduction Sexually related infections, including cystitis and vaginitides in the female, and cystitis, urethritis and prostatitis in the male, as well as infections of the external genitalia in both genders were previously thought to be uncommonly transmitted from member to member of a dyad. Newer microbial detection techniques have allowed for more rapid identification of potential pathogens. However, persistence of an infection in a partner remains a perplexing diagnostic and therapeutic dilemma, raising the question of transmission of an infectious organism from a potentially asymptomatic partner. Objective To evaluate the benefit of mutual, synchronous microbial detection assays in dyads in whom at least one partner has a persistent, symptomatic infection that could be transmitted by sexual activity. Methods Twenty-six (26) heterosexual, monogamous couples underwent synchronous microbial testing including traditional laboratory culture techniques and polymerase chain reaction (PCR) and next generation sequencing (NGS) with a urine specimen, superficial and deep vaginal swab specimens in the female and urine and semen specimens in the male. Both genders had swab specimens of the external genitalia. The female member was symptomatic in 17 of the couples, the male in 4, and both were symptomatic in 5 couples. Results from all assays were tabulated and comorbid pathogens were treated with concurrent appropriate antimicrobials, using guidelines for therapeutic choices and duration of antimicrobial course. Sexual abstinence was required for the duration of the antimicrobial therapy. To assess efficacy, repeat assays were done after a time frame sufficient to allow for relapse/recurrence of the infection. Results Traditional culture techniques failed to demonstrate the significant pathogen(s) in at least one member of the dyad in all but 3 couples. This failure emerged from two primary foci: one methodological, in which automated techniques discarded specimens with low microbial growth or multiple organisms. The other was failure to identify the organism entirely. PCR identified the pathogen in at least one member in 11 of the 26 dyads, but NGS detected pathogens in both members in all the couples. Novel pathogens were detected, organisms previously thought to be commensal or contaminants. Multiple pathogen detection was common, occurring in 17 couples. Conclusions A frequent concern of patients and clinicians for those patients who have persistent, potentially sexually related infections is the underlying contribution from a partner. Limitations in accurate microbial detection often complicate eradication of the infection. Only NGS found significant pathogens on synchronous assays of all dyads tested, allowing organism specific concurrent antimicrobial therapy of both members. These results suggest a new algorithm for detection and therapy in patients whose persistent infection may involve the contribution of a partner. Disclosure No