Diagnosing a spider bite is difficult because confirmation requires an eye witness to the bite, exclusion of other causes and expert identification of the spider, notes Mayo Clinic. Multiple conditions can also appear similar to spider bites, including skin disorders, infections and other bites, explains the Merck Manual Professional Edition.
Most spiders are not able to bite because their fangs are too short or fragile, according to the Merck Manual Professional Edition. Mistaking infections such as methicillin-resistant Staphylococcus aureus for spider bites is common, and doctors rule this out in the course of diagnosis. Treatment for most spider bites involves basic wound care, elevating the extremity that has the bite, using ice to reduce swelling and pain, and possibly a tetanus booster shot.