Chronic Lyme arthritis: A mystery solved?

By John Ross, MD, FIDSA: For More Info, Go Here…

In 1975, researchers from Yale investigated an epidemic of 51 patients with arthritis who lived near the woodsy town of Lyme, Connecticut. The most common symptom was recurrent attacks of knee swelling. A few had pain in other joints, such as the wrist or ankle. Many had fever, fatigue, and headache. Some remembered a round skin rash before the onset of knee swelling.

We now know that Lyme disease is an infection acquired from tick bites, caused by a spiral bacterium named Borrelia burgdorferi. After a tick bite, Borrelia bacteria wriggle through the skin away from the bite site. This leads to a circular red rash, known as erythema migrans. In its more advanced stages, erythema migrans may take on a bullseye appearance. Many people are unaware of the rash, as it is usually painless, and ticks may bite in less visible locations, such as a buttock or shoulder blade.

Lyme disease is diagnosed with blood tests that detect antibodies to B. burgdorferi. Two-step testing is traditionally performed. A rapid enzyme immunoassay is performed first. If this is positive, a more time-consuming Western blot test is sent for confirmation. The FDA recently approved two rapid tests for Lyme disease that are performed simultaneously, reducing the turnaround time.

Lyme disease often leads to Lyme arthritis

Although Lyme disease may affect many organs, such as the heart and nervous system, joint involvement tends to be the most common and persistent manifestation, resulting in joint swelling and pain. About 60% of people who are infected with Lyme develop arthritis unless they receive antibiotics.

In most, Lyme arthritis resolves after 30 days of treatment with an oral antibiotic, such as doxycycline or amoxicillin. Individuals with persistent symptoms despite an oral antibiotic usually respond to treatment with an intravenous antibiotic for 30 days. However, about 10% of those with Lyme arthritis fail to respond to antibiotic treatment, for reasons that have long been unclear.

Fragments from Lyme bacteria persist in joints, even after the bacteria are killed off

new study published in Proceedings of the National Academy of Sciences sheds light on this medical mystery. To keep from spilling open, bacteria have rigid cell walls made of a matrix of protein and sugars, called peptidoglycan. Most bacteria recycle their peptidoglycan when they grow and divide, but the peptidoglycan of B. burgdorferi has a peculiar structure, and the bacteria is unable to reuse it. Instead, it dumps it into its immediate surroundings, like a microbial litterbug.

This peptidoglycan collects in the joints where B. burgdorferi is found. Almost all patients in the PNAS study with Lyme arthritis had peptidoglycan in their joint fluid. Most of them also had specific antibodies to peptidoglycan in the joint fluid, suggesting that the peptidoglycan was driving the inflammatory process

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