Does it have a nasty aroma? That will not go away with boiling. Not sure if I had same infection but I once mashed, then sparged but circumstances prevented me from boiling till next night. White foam had formed on the top of wort. It smelled of malty goodness when it first hit my nose, but then the acrid scent of vommit followed. I don't think mine was lactic. I boiled it for twenty minutes and the smell seemed to lessen as it heated, but I gave up and dumped after cooling. The smell came back strong again when cool. Tasted fine, but I knew I wouldn't drink anything that had a malty puke smell reaching my nose before I imbibe it. If you're brave, try it. If you mash, you at least have to sparge and keep wort above 160 for 15min to pasteurize, or something like that. I have several times mashed and sparged/pasteurized in the evening and boiled following morning. Not sure what the worst effects on the wort would be, aside from nasties, however I'm sure someone else knows.