Diagnosis of Fungal Infection

The pathogens involved in this outbreak are still under investigation. Thorough and rapid diagnostic evaluation is essential to identify pathogens causing infections in patients who received contaminate steroid injections from the New England Compounding Center. The proper identification of pathogens may have implications for the nature of and duration of antimicrobial therapy.

These instructions are meant to supplement routine laboratory and microbiologic tests deemed necessary by the clinician and should not replace existing diagnostic protocol.

A negative fungal culture or negative fungal polymerase chain reaction (PCR) test from a diagnostic specimen obtained from CSF, a parameningeal site, a joint space, or bone does not rule out infection. Active fungal infection may be present even when these tests are negative.

Diagnosis of Localized Spinal / Paraspinal Infection

The majority of cases in this outbreak, currently being reported to CDC, are localized spinal or paraspinal infections (i.e., epidural abscess, phlegmon, discitis, vertebral osteomyelitis, arachnoiditis, or other complications at or near the injection site).

These localized infections may occur on their own or in patients previously diagnosed with fungal meningitis. Although patients with these localized infections frequently have new or worsening back pain, symptoms may be mild or clinically difficult to distinguish from the patient’s baseline chronic pain. Some of these cases have occurred in patients with back pain symptoms at or near baseline. Based on current information, CDC recommends the following protocol:

• In patients with new or worsening symptoms at or near the injection site, physicians should obtain an MRI with contrast of the symptomatic area(s), if not contraindicated. This recommendation also applies to patients being treated for meningitis. In some cases, radiologic evidence of abscess or phlegmon has become apparent on repeat MRI studies performed subsequent to an initially normal imaging procedure. Clinicians should therefore have a low threshold for repeat MRI studies in patients who continue to have symptoms localizing to the site of injection, even after a normal study. However, the optimal duration between MRI studies is unknown.
• Clinicians should consider obtaining an MRI with contrast of the symptomatic area(s) in patients with persistent but baseline symptoms following spinal or paraspinal injection of the implicated MPA because the presentation of these spinal or paraspinal infections can be subtle and difficult to distinguish from a patient's baseline chronic pain.
• CDC has received reports of patients being treated for fungal meningitis who had no previous evidence of localized infection at the site of injection, but who were subsequently found to have evidence of localized infection on imaging studies. Therefore, in patients being treated for meningitis, even in the absence of new or worsening symptoms at or near the injection site, clinicians should strongly consider obtaining an MRI of the injection site approximately 2-3 weeks after diagnosis of meningitis. Early identification of new disease may lead to additional specific interventions (e.g., drainage).
• Patients who have epidural abscess, phlegmon, discitis, vertebral osteomyelitis, or arachnoiditis, should speak with a neurosurgeon to discuss whether surgical management, including debridement, is warranted in addition to antifungal therapy. If a surgical procedure is performed, potentially infected fluid collections should be sampled and sent for microbiologic testing (including fungal smear).
• Any relevant tissue specimens sent for histopathology should be stained and reviewed for infectious agents, including fungi (silver stain). Save specimens to send to state health departments and CDC for further evaluation. If fresh tissue can be saved, freeze at -70°C. See attached guidance for specimen collection and processing.

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Diagnosis of Central Nervous System Infection

Cerebrospinal fluid (CSF)

When possible, collect a large volume of cerebrospinal fluid (CSF), ideally using a different site than was used for the epidural injection. Obtain routine gram stain and bacterial cultures, including aerobic and anaerobic. The priority for remaining CSF specimens is fungal culture, conducted at the local hospital or state lab. When possible, submit a large volume of CSF (minimum 10mL) for fungal culture.

Remaining CSF may be sent to CDC for a polymerse chain reaction (PCR) test. The minimum volume should be 1 mL; 5 mL is preferred. Samples sent to CDC should be unspun samples or freshly collected, unadulterated samples. If only a small volume can be obtained for CDC and the patient meets the case definition, send what you can.

• CSF should be sent to CDC only on patients with CSF results showing >5 white blood cells (use traumatic tap correction for WBC), regardless of glucose or protein levels.

Specifically for the work-up of possible fungal pathogens:

• Attempt to obtain larger volume of CSF to culture for fungi from intraventricular shunts/drains if patient presents with these.

All cultures should be incubated for at least 2 weeks prior to discarding.

Other tests

In addition to routine blood cultures, consider obtaining fungal blood cultures. Other potentially infected fluid collections should be sampled (e.g., aspiration of epidural abscess) and sent for microbiologic testing as described above for CSF specimens (including fungal smear). Any relevant tissue specimens sent for histopathology should be stained and reviewed for infectious agents, including fungi (silver stain). Save specimens to send to state health departments and CDC for further evaluation. If fresh tissue can be saved, freeze at -70°C.

Send available autopsy specimens to CDC for further evaluation.

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Diagnosis of Joint Infection

Perform arthrocentesis (or arthroscopy, in consultation with an orthopedic surgeon) to obtain synovial fluid for analysis. Synovial fluid should be sent for fungal culture, in addition to cell count and differential, routine Gram stain, bacterial cultures, and examination for crystals. Send remaining synovial fluid to CDC for PCR (ideally ≥ 1 mL).

If initial presentation or diagnostic testing suggests severe infection, consider arthroscopy, in consultation with an orthopedic surgeon, to obtain synovial fluid and tissue and to perform lavage and/or debridement.

• Send synovial fluid and tissue specimens for microbiologic testing as described above. In addition, send tissue specimen for histopathology, including silver staining, to look for fungi.
• Send remaining synovial fluid and tissue specimens to CDC for further testing. If fresh tissue can be saved, freeze at -70°C.
• Any relevant tissue specimens sent for histopathology should be stained and reviewed for infectious agents, including fungi (silver stain). Save specimens to send to state health departments and CDC for further evaluation. If fresh tissue can be saved, freeze at -70°C. See attached guidance for specimen collection and processing.

Radiographic imaging studies, such as MRI, may be considered to evaluate for osteomyelitis. Imaging may be particularly important in the evaluation of joint spaces such as the sacroiliac joint, where osteomyelitis may be more common and from which obtaining a diagnostic specimen of synovial fluid may be more difficult. Similarly, for patients in whom complaints of back pain are worrisome for the development of discitis/vertebral osteomyelitis, imaging should be performed. In some of these cases, repeat imaging may be required as the progression of the infection may be slow and imaging findings suggestive or diagnostic of osteomyelitis may not be evident for weeks following initial presentation. If osteomyelitis is suspected, arthroscopic biopsy and debridement in consultation with an orthopedic surgeon is recommended. Tissue specimen should undergo testing and submission to CDC as described above.

Specimen Shipping Information

Please contact your state health department and state public health laboratory to coordinate shipment of specimens to CDC for further testing.

CDC's PCR test for detection of fungal DNA

CDC has developed a novel test using PCR and DNA sequencing to detect fungal DNA in cerebrospinal fluid (CSF), other body fluids, and tissues from patients in this outbreak. To assess the performance of this PCR test, CDC tested 627 samples from 413 case-patients. The main results of the validation study are as follows:

• The PCR test detected Exserohilum rostratum DNA in 123 samples from 114 case-patients (28% of the 413 case-patients for whom samples were available). The test also detected Cladosporium sp. DNA in one case-patient.
• PCR was more sensitive than culture. Of 139 case-patients who had a specimen tested by both PCR and culture, E. rostratum DNA was detected by PCR in 41 (29%) but was only recovered from culture in 19 (14%). In total, 33% of case-patients had fungi detected in specimens by either culture or PCR.
• There were no false-positive PCR results (100% specificity). Among 136 specimens from patients who did not meet the case definition, all were negative.

The full results of the study performed to validate this PCR test are available here. The results suggest that the test is a useful tool to quickly detect fungi in body fluids and tissues, and it can detect fungal DNA in specimens that may not have shown any fungus in culture.

However, PCR for fungal detection is still a research test that has not been cleared or approved by the FDA and should not be used for diagnosis, treatment, or assessment of patient health or management. In addition, for both PCR and culture, a negative result does not rule out infection.

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