Seronegative Lyme Disease: Culture Evidence After Antibiotic Treatment

Geographic Expansion into the Southeast

Seronegative Lyme disease may be more common than recognized, particularly as Lyme disease expands geographically. Scientists are increasingly focusing their attention on identifying tick-borne pathogens present in the Southeastern United States. :contentReference[oaicite:0]{index=0}

In 2015, Lantos and colleagues reviewed the geographic expansion of Lyme disease in the Southeast over the past 14 years. They found “a marked increase in Lyme disease cases in Virginia, particularly from 2007 onwards … with development of a new disease cluster in the southern Virginia mountain region.”

Since 2009, five counties in North Carolina have been considered endemic for Lyme disease. The introduction of tick-transmitted diseases into new areas is likely to continue, with expansion expected into neighboring states such as Kentucky, West Virginia, and Tennessee.

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First Recovery of Live Borrelia from Southeast Residents

Rudenko and colleagues studied 24 individuals living in the Southeastern United States who had been treated for suspected tick-borne illness.

Participants included residents of North Carolina, Georgia, and Florida. Seventy-one percent recalled a tick bite, and 50% had a lesion consistent with a tick bite, ranging from a few centimeters to 9–12 centimeters in diameter.

The authors described the patients as having “undefined disorders” with symptoms not typical for Lyme borreliosis, despite receiving antibiotic treatment and testing negative by standard criteria.

Common symptoms included:

• Severe headache and nausea
• Muscle and joint pain
• Numbness and tingling in extremities
• Neck and back pain
• Panic attacks and depression
• Dizziness and vision problems
• Sleep disturbances and shortness of breath

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Successful Cultivation Despite Seronegative Status

The researchers successfully cultivated Borrelia burgdorferi and Borrelia bissettii-like spirochetes from these patients.

This represents:

• The first recovery of live Borrelia burgdorferi sensu stricto from residents of the Southeastern United States
• The first successful cultivation of Borrelia bissettii-like organisms from a North American human

These findings demonstrate that viable infection can exist even in patients who are seronegative by CDC surveillance criteria.

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Modified Culture Medium Enables Detection

A modified Kelly-Pettenkofer medium was used rather than standard BSK-H medium.

This difference is important, as standard media may not support optimal growth of all Borrelia strains.

The cultured organisms were confirmed through:

• DNA sequencing
• PCR amplification
• Multilocus sequence analysis (MLSA)
• Transmission electron microscopy

These methods provided definitive identification and ruled out contamination.

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Borrelia bissettii: An Emerging Pathogen

Borrelia bissettii has been identified in ticks and wildlife across North America and Europe.

It has been detected in human samples, including serum and cardiac tissue, but had not previously been cultured from a North American patient.

Infection with B. bissettii can produce Lyme-like symptoms, including:

• Flu-like illness
• Joint pain
• Muscle aches
• Weakness

This finding suggests that additional Borrelia species may contribute to illness often labeled as “seronegative Lyme disease.”

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Why These Patients Typically Would Not Be Studied

The authors acknowledged that these patients would normally be excluded from research studies because:

• The Southeast is not considered endemic by the CDC
• Patients were seronegative
• They had already received extended antibiotic treatment
• The study was retrospective
• Reinfection could not be ruled out

These exclusions may prevent recognition of atypical or persistent cases in standard research.

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Persistence After Extended Antibiotic Treatment

Live spirochetes were cultured from patients who had received prolonged antibiotic therapy—some up to 9 months of doxycycline.

This finding raises important questions about treatment response and persistence.

Possible explanations include:

• Antibiotic tolerance in protected tissue environments
• Persister cells resistant to standard antibiotics
• Inadequate dosing or duration
• Reinfection

These findings suggest that extended antibiotic treatment does not guarantee eradication of infection.

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Frequently Asked Questions

Was live Borrelia cultured from Southeast US patients?
Yes. This study represents the first recovery of live Borrelia from residents of the Southeastern United States.

Were these patients seronegative?
Yes. All patients tested negative by CDC criteria despite having cultivable organisms.

Can Borrelia be cultured after antibiotic treatment?
Yes. Viable spirochetes were recovered even after prolonged antibiotic therapy.

What is Borrelia bissettii?
A Borrelia species found in ticks and wildlife that causes Lyme-like symptoms.

Why is the Southeast not considered endemic?
CDC surveillance has historically focused on the Northeast and Midwest, though evidence suggests broader distribution.

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Clinical Takeaway

This study demonstrates that live Borrelia can be cultured from seronegative patients—even after extended antibiotic treatment.

Patients in this study lived in regions not considered endemic, tested negative using standard criteria, and had already undergone prolonged treatment—yet viable organisms were identified.

These findings highlight limitations in current diagnostic testing and underscore the importance of clinical judgment in Lyme disease.

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Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention