'American Idol' Bikini Girl Pleads Not Guilty to DUI

Katrina Darrell -- the girl who infamously auditioned for "American Idol" back in 2009 wearing just a bikini -- insists ... she isn't a drunk hit-and-runner ... pleading "not guilty" to DUI today.

TMZ broke the story ... Katrina was charged last month with one count of DUI and two counts of misdemeanor hit-and-run, stemming from her March arrest.

As we reported, Katrina was busted in L.A. after allegedly running a red light and smashing into another car. According to police, Katrina attempted to flee the scene ... but was pulled over down the street by a cop who heard the crash.

Back at the police station, an officer administered a breathalyzer -- and Katrina allegedly blew roughly twice the legal limit in California.