Feces and infection question ---(may be a little disgusting)

Is it the fecal coliform that caused the rashes, or is there something else in the feces that might be the cause of irritation? I mean, like, HCl frintance? How much HCl from the stomach is left over in the feces after passage through the bowels?

Maybe I’ll try asking the gastroenterologists at work. They’re pretty good with gross answers to honest poop questions.