Table of ContentsView AllTable of ContentsSigns and SymptomsComplicationsWhen to Seek Medical CareTreatment
Table of ContentsView All
View All
Table of Contents
Signs and Symptoms
Complications
When to Seek Medical Care
Treatment
Spider and other insect bites can cause pus blisters, but so can a potentially serious infection known as methicillin-resistantStaphylococcus aureus(MRSA). While bites and infections can be confused, there are ways to tell them apart.
Spider bites and other insect bites can cause one or several rashes or lesions, with fluid-filled blisters calledbullae. Although MRSA looks very similar, it typically causes multiple rashes with small, pus-filled bumps calledpustules.
Spider bites, other insect bites, and MRSA are sometimes particularly difficult to tell apart, especially in the early stages when symptoms are just starting to emerge.
This is why it is important to monitor any suspected insect bite for changes in its appearance or numbers. It may not end up being an insect bite at all. And if it’s MRSA, fast treatment is needed.
Appearance of Blisters
If you get several in the same spot, you may experience a purplish discoloration of the skin with swelling, pain, warmth, and hardening. In contrast, MRSA causes bumps that are red or discolored, swollen, warm to touch, painful, or pustules filled with pus or other drainage.
Number of Bumps
While spider bites tend to be solitary, it is possible to get a few separate bites at once.
MRSA may start with one or several bumps, but the rash almost invariably grows in size and amount, causing a cluster of pustules that can merge into a larger pus-filled mass.
Both MRSA and spider bites can lead to serious complications. With spider bites, complications are related to how venomous the particular spider involved is and/or how vulnerable or sensitive you are to the venom. With MRSA, the concern is related to the dissemination (spread) of the infection internally. Other issues can arise with different insects.
These complications, some of which are life-threatening, further underscore the importance of telling the two conditions apart and getting treated quickly, if needed.
Spider Bites
There are five types of venomous spiders that cause the most risk for human, including the black widow, brown recluse, and hobo spider.The spider venoms are neurotoxic, meaning that they attack the nervous system.
Most cases causeheadaches, lethargy, irritability,muscle pain,tremors, and impaired coordination. But, in severe cases, potentially life-threatening complications can rapidly develop. They include:
Anaphylaxis(a potentially life-threatening, whole-body allergy) can occur with spider bites.
Bug Bites
Beyond spiders, other insect bites and stings can lead to complications beyond discomfort. The life-threatening anaphylaxis that can occur with spiders also can happen with bee stings and black ants.Other conditions can include:
MRSA
In most cases, MRSA causes a mild skin infection. If left untreated, however, MRSA can cause complications affecting multiple organ systems.
This occurs when the bacteria disseminate beyond the skin through blood andlymph vessels, causing a systemic (whole-body) infection. Some of the possibly life-threatening complications include:
When to Call a Healthcare Provider
Knowing the difference between a spider bite and MRSA can help you respond appropriately, particularly in emergency situations. As a rule of thumb, if you’re not sure what your blister or rash is but are worried, have it checked out.
Call 911 or seek emergency medical treatment if you experience any of the following after getting or finding what you think might be a bite of any kind:
Seizures, loss of consciousness, and even death can occur without immediate treatment of certain insect bites, including the black widow spider.
Insect bites from spiders, mosquitoes, fleas, and more often require no treatment unless you have a severe reaction. The same cannot be said for MRSA because it can be so easily spread.
If you suspect a spider bite:
Seek medical care right away for a spider bite if you:
If you suspect an insect bite:
Seek medical treatment for an insect bite if you:Have worsening symptomsWere stung in your mouth, throat, or near your eyesHave stomach pain and/or vomitingFeel dizzy or lightheadedHave redness and swelling over a large area around the biteDevelop a high fever and swollen glandsHave been bitten more than onceHave had a serious allergic reaction to an insect bite beforeDevelop joint pain, swelling, and a rash several hours afterward
Seek medical treatment for an insect bite if you:
Antibiotics with demonstrated activity against MRSA include:
If placed on the appropriate antibiotics, the symptoms of MRSA will usually resolve within seven to 14 days.
If you are prescribed oral antibiotics, you need to take the drugs as prescribed and to completion even if you’re feeling better. If you don’t, the infection may return. Worse yet, a more resistant strain may emerge and be harder to treat.
Signs MRSA Treatment Is Not Working
With that said, certainMRSA strainsare harder to treat and may not respond as quickly or as well. In such cases, you would need to see a healthcare provider if:
Symptoms that don’t respond to antibiotics, or that return soon after antibiotic therapy is completed, need to be reported to your provider.
Summary
It can be hard to tell the difference between a spider bite and MRSA. The most important clue may be the kind of blister that forms. MRSA blisters contain pus and spider bites contain fluid. Eventually, MRSA boils often expand and spread.
MRSA is an antibiotic-resistant bacteria that can be found in lots of community settings. If it’s not treated, it can enter the bloodstream and cause life-threatening infections.
13 Sources
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