Can SAPHO Syndrome Occur With a Bacterial Bone Infection?

Yes, it is possible to have both SAPHO syndrome (which typically involves aseptic or sterile bone inflammation) and a true bacterial bone infection (bacterial osteomyelitis) at the same time. While a hallmark of SAPHO is sterile inflammation without bacteria, having this diagnosis does not protect you from common bacterial infections ^[1][2]. In fact, it is critical not to assume that every new or worsening symptom is simply another SAPHO flare. If your symptoms change or worsen significantly, a prompt medical examination and targeted testing are necessary to rule out a coexisting bacterial infection.

Recognizing the Difference: Flare vs. Infection

Distinguishing a typical SAPHO flare from a true bacterial infection can be difficult because they share many features. Pain, swelling, warmth, and elevated inflammatory markers in your blood—such as ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein)—can occur in both situations ^[3][4][5]. While a mild, low-grade fever may sometimes happen with inflammatory diseases, a high fever or feeling systemically unwell is not a typical SAPHO symptom to ignore ^[5].

When to Seek Immediate Care

Do not wait for a routine appointment if you experience signs that could indicate a dangerous infection.

Seek emergency medical care if you develop:

• Confusion or fainting
• Difficulty breathing
• Severe weakness or rapid deterioration

Contact your care team for a same-day urgent assessment if you experience:

• A new, high fever or severe, shaking chills (rigors)
• Rapidly progressive, sharply localized bone pain ^[6]
• Unusually severe swelling, spreading redness, or the appearance of an abscess or fluid collection ^[7][8]
• Any drainage, pus, or breakdown of the skin over a painful bone

Risk Factors for Coexisting Infections

Your risk for developing a true bacterial infection alongside SAPHO increases in certain situations:

• Immunosuppressive Treatment: If you are taking biologic therapies, corticosteroids, or other immunosuppressant medications, your immune system’s ability to fight off infections may be reduced ^[9][10]. The risk varies depending on the specific medication, dose, and your overall health. Never stop or skip your SAPHO medications without your doctor’s instructions, but contact them promptly if you suspect an infection.
• Recent Surgery, Procedures, or Hardware: Invasive procedures can introduce bacteria into the body ^[11]. Having orthopedic hardware, such as plates or joint replacements, also raises the risk of a localized infection ^[12]. Note that having SAPHO alone does not generally mean you need preventative antibiotics before routine dental work; such prophylaxis is reserved for specific guideline-defined situations, and you should not self-start antibiotics.
• Wounds or Bloodstream Infections: An open wound, an active skin infection, or recent bacteria in your bloodstream increases the chance that bacteria could travel to the bone and cause an infection.

The Importance of Targeted Testing

Because no single test can perfectly distinguish a SAPHO flare from a bacterial infection, your medical team will use an individualized approach ^[1][7]. This evaluation often includes:

• Medical Imaging: MRI is generally the preferred imaging test to evaluate bone infections, though CT scans are used in certain situations ^[13][14].
• Blood Cultures: If you have a fever or feel systemically ill, blood cultures can help identify bacteria in your bloodstream ^[15].
• Tissue Sampling: A bone biopsy or deep-tissue culture (taking a sample from deep inside the affected area) may be considered, especially if blood cultures are negative and you are stable ^[16].

Interpreting tissue tests requires careful medical judgment. Some bone biopsies from people with SAPHO test positive for certain low-virulence (less aggressive) bacteria, such as Cutibacterium acnes, which is common on the skin ^[17][5]. A single positive culture could simply be contamination from the skin. However, it can also cause a true, slow-growing infection, especially around hardware ^[12]. Doctors will consider the number of positive samples, the collection technique, tissue pathology (examining the tissue under a microscope for signs of infection), and imaging to decide if it is a true infection ^[18][8].

What Happens if an Infection is Confirmed?

If bacterial osteomyelitis is confirmed, treatment usually involves targeted antibiotics based on the specific bacteria found. Depending on the severity, it may also require drainage or surgery to remove an abscess, dead bone, or infected hardware ^[7]. Your medical team—which may include infectious disease and orthopedic specialists—might also need to temporarily adjust your immunosuppressive SAPHO medications. This process requires expert coordination, which is why obtaining the correct diagnosis is so important.