FMO5 and infection: In addition, the percentages of live leptospires in THP-1 cells decreased slightly during the whole infection process compared to leptospires in EMJH medium (P<0.05), while less change was observed in the percentages of live leptospires in NADPH oxidase inhibitor apocynin pretreated THP-1 cells and THP-1 cells without apocynin pretreatment.