Expert advice and patient expectations: laboratory testing and antibiotics for Lyme disease

Management of suspected Lyme borreliosis: experience from an outpatient parenteral antibiotic therapy service

OBJECTIVES

Lyme borreliosis (LB) is the most common human tick-borne infection in Europe and the USA. In this study we set out to analyse the outcome of patients treated for Lyme disease via outpatient parenteral antibiotic therapy (OPAT) and the appropriateness of this treatment using current guidelines.

METHODS

This was a retrospective review of all patients with suspected LB managed via OPAT in Glasgow in 2000-11.

RESULTS

Of 72 patients treated for suspected LB, 35 patients (49%) were treated in accordance with guidelines and 36 (50%) were treated with no specific guidelines. A definite improvement was seen in 20 patients (28%). Adverse reactions were documented in 29 (40%) patients with neutropenia, and mild liver function derangement was most commonly observed.

CONCLUSION

These results show the complexity of translating well-substantiated regimens from clinical trials to actual clinical practice. OPAT was an effective way of administering parenteral therapy for Lyme disease but should not be undertaken lightly due to the rate of adverse events and low rates of success in certain patient groups seen in this study. In view of this, stricter criteria for inclusion to OPAT in line with published guidance should be applied to minimize patient harm and optimize success.

Laboratory testing for suspected Lyme disease

Laboratory testing for B. burgdorferi infection is intended to substantiate a physician's clinical judgment of whether a patient has Lyme disease or not. Cultivation of B. burgdorferi from a patient's skin or blood is the gold standard for demonstration of active infection, but it is expensive and lacks clinical sensitivity. Detection of spirochetal DNA in clinical samples by PCR has better sensitivity, but PCR for B. burgdorferi has not yet been standardized for more routine diagnostic testing. Detection of antibodies to B. burgdorferi is the most practical and common approach for laboratory work-up of a case of suspected Lyme disease. Serologic assays fall short of 100% sensitivity and specificity, however, and examination of a single specimen in time does not discriminate between previous and ongoing infection. Because of a background false positivity even among healthy populations of nonendemic regions, serologic testing is recommended only when there is at least a one in five chance, in the physician's estimation, that the patient has active Lyme disease. The pretest likelihood of the disease is determined by the physician in the context of epidemiologic and clinical facts of the case. This estimate can serve to reassure patients who are at low risk of B. burgdorferi infection but are seeking a Lyme test for complaints of a more nonspecific nature. Although new subunit serologic assays based on recombinant proteins are becoming available commercially, the longstanding two-test approach, in which a positive or indeterminate result with a standardized, sensitive ELISA test is followed by verification with a more specific Western blot assay, still provides the physician with a reasonably accurate and reliable assessment of the presence of antibodies to B. burgdorferi. More recent challenges for serologic testing are seropositivity in the population as the result of immunization with the Lyme disease vaccine and the emergence of new Borrelia species that cause Lyme disease-like illnesses.

Tick bite and Lyme borreliosis risk at a recreational site in England

The risk of tick bite and Lyme borreliosis in a forested area in England with public access was studied over a two-year period. Tick infestation levels were high with more than 1000 members of the public reporting for tick removal at a local clinic. Most of the attached ticks were nymphs (82%) and distinct differences in anatomical sites of attachment were observed in children and adults. Children sustained nymphal bites to the head, neck and axilla region much more frequently than adults (48 vs. 10%), whereas adults were bitten on the lower legs more frequently than children (46 vs. 9%). The vegetation was heavily infested with ticks and high numbers were particularly associated with areas used by deer. The average density of nymphs collected from the vegetation was 14.1 per 10 m2 (range 5.1-43.6). Infection rates of these nymphs determined by PCR and indirect IFA ranged from 5.2-17.0%, and the genospecies Borrelia valaisiana and B. garinii were detected, suggesting that birds may be important reservoir hosts in this area. It is estimated that, at the level of tick challenge observed here, at least 50 persons per year may be bitten by infected ticks at this site. However, no cases of Lyme borreliosis have been reported through the clinic follow-up procedure, and sera from 19 forest workers were negative for antibody to B. burgdorferi sensu lato. Despite the high challenge from tick bites, this particular recreational forest site poses a low risk of infection to the general public, and prophylactic antibiotic treatment or serological testing following a bite is not justified.

Lyme borreliosis

Lyme borreliosis is a worldwide, multistage, and multi-system disease caused by borrelia spirochetes, which are transmitted by ixodes ticks. It is focally endemic in temperature climates of the northern hemisphere. Primary erythema migrans occurs at the site of inoculation. Secondary erythema migrans occurs at sites of hematogenous dissemination. Variations in genospecies account for variations in presentation, including borrelial lymphocytoma. Disseminated disease includes constitutional signs and symptoms, intermittent oligoarticular arthritis, meningitis, cranial neuritis, radiculoneuropathy, encephalopathy, atrioventricular block, and myopericarditis. Late persistent disease includes acrodermatitis chronica atrophicans, chronic arthritis, neurological impairment, and fatigue. There can be difficulties with both clinical and laboratory diagnosis. First-line oral therapies for early uncomplicated disease are doxycycline and amoxicillin. First-line intravenous therapy for complicated or resistant disease is ceftriaxone. Prevention includes avoiding tick habitats, dressing sensibly, judicious use of repellants, and early removal of imbedded ticks. Vaccination is indicated only for frequent or prolonged exposure to tick-infested habitat.

Lyme disease

Lyme disease (LD) is the most common tick-borne disease in the United States. The overall trend has been an average annual increase in reported cases since surveillance was initiated by the Centers for Disease Control and Prevention in 1982. Ixodes ticks often carry more than one potential pathogen, and co-infection with Borrelia burgdorferi and other organisms has been reported. The impact of dual infection upon the clinical course of LD is not known. Further studies of erythema migrans-like rashes in the Southern United States have indicated that it is likely caused by a related spirochetal organism. Case reports of unusual presentations have broadened our understanding of the clinical spectrum of LD. Studies in patients with chronic Lyme arthritis have indicated that an autoimmune process may be responsible for such cases. Results of two large, placebo-controlled trials of a recombinant Lyme vaccine have been reported and results indicate that the vaccine is safe and effective in preventing LD in adults.