i have a mac os x 10.5.8 and i cannot read sd cards through a usb adapter

I have a 2009 mac book pro current version 10.5.8 and i cannot read any sd card/micro sd with my sd card usb adapter as my laptop does not have a slot for them. I have tried different usb adapters and still get the message, "disk insertion: the disk you inserted was not readable by this computer" options for initialize... ignore and eject. I have tried initializing and repairing the drive as the prompt instructed with no success, is this a problem with my sd cards? or should I contact the manufacturer.