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DIAGNOSIS: Clinical Laboratory: Polymerase Chain Reaction


The polymerase chain reaction (PCR) technology emerged in 1988 and has greatly assisted in the detection and identification of a wide range of fastidious pathogens. PCR methods are now available that are species-specific and can detect low copy numbers of B. burgdorferi s.l. Since PCR (in contrast to culture) only detects spirochaetal DNA but not viable organisms a positive PCR, although suggestive cannot unequivocally establish whether infections are active or not. . Nevertheless, it is a particularly valuable tool in both the diagnosis and clinical management of patients with arthritis, since isolation of borreliae from synovial fluids is almost always unsuccessful and serology cannot distinguish between chronic active and past infections.

In contrast PCR can detect borrelia DNA in >50% of synovial fluid samples and even higher levels of detection of DNA in synovial membranes can be achieved. In EM and ACA patients, borrelia DNA has been detected in 50-70% of the skin biopsies and rarely in serum. In acute neuroborreliosis patients, borrelia DNA was detected in 20% to 30% of the cerebrospinal fluid samples tested though in a few cases higher detection rates were found. The utility of urine-PCR has been investigated by several groups, but results are rather contradictory and urine PCR is therefore not recommended for routine diagnosis.



PCRs are now available that detect and identify individual genospecies of B. burgdorferi sensu lato. These methods either use species-specific primers for PCR, or analyse the PCR product by DNA sequencing, hybridisation to species-specific probes, or restriction endonuclease polymorphism. Mixed infections of 2 or 3 different species have been detected in European neuroborreliosis patients and patients with an EM or ACA. Despite the occurrence of mixed infections, the association of B. afzelii with ACA remains unchallenged. In neuroborreliosis about 60-70% of the strains belong to the species B. garinii and so far the majority of isolates from European Lyme arthritis cases have proved to be B. burgdorferi s.s., though several studies have reported genospecies heterogeneity in Lyme arthritis cases.