Russell C. Johnson

Borrelia burgdorferi sp. nov.: Etiologic Agent of Lyme Disease

A review of reports on the genetic and phenotypic characteristics of strains of the spirochete which causes Lyme disease revealed that these organisms are representative of a new species of Borrelia. We propose the name Borrelia burgdorferi for this species. The type strain of B. burgdorferi is strain B31 (= ATCC 35210). In two separate studies the guanine-plus-cytosine content of the deoxyribonucleic acid of the type strain was determined to be 29.0 to 30.5 mol% (thermal denaturation method).

Azithromycin compared with amoxicillin in the treatment of erythema migrans : A double-blind, randomized, controlled trial

Lyme borreliosis is the most common vectorborne disease in the United States and Europe [1]. Infection begins as a local process after Borrelia burgdorferi is inoculated into the skin by a feeding tick. In most persons, the initial sign of infection is the development of erythema migrans, which is characterized by an annular erythematous skin lesion. Amoxicillin and doxycycline have been advocated as the treatments of choice, primarily on the basis of small, often unblinded, randomized trials and retrospective analyses [2-4]. Azithromycin, an azalide (a new subclass of macrolide antibiotics), has been shown to have excellent in vitro and in vivo activity against B. burgdorferi in the laboratory [5, 6]. In a small, randomized, open study on the treatment of erythema migrans, a 5-day course of azithromycin was reported to be as effective as a 10-to 20-day course of doxycycline or amoxicillin with probenecid [7]. To more thoroughly assess the efficacy of azithromycin and further define the treatment of erythema migrans, we conducted this large, multicenter, double-blind, randomized trial. Amoxicillin rather than doxycycline was chosen as the comparative agent to circumvent the problems associated with sun-related hypersensitivity reactions. During the study, we clarified important clinical questions about the natural history of this disease, its manifestations, and the usefulness of enzyme-linked immunosorbent assay (ELISA) for serologic testing. Methods Patients Adult patients who had had erythema migrans diagnosed by a physician were recruited between June 1990 and October 1991 from 12 centers in eight states: New York (83 patients), Connecticut (85 patients), Missouri (35 patients), Wisconsin (23 patients), New Jersey (10 patients), Minnesota (6 patients), California (2 patients), and Rhode Island (2 patients). To be eligible for the study, patients had to be at least 12 years of age and had to weigh at least 45 kg. Erythema migrans lesions at least 5 cm in diameter were photographed for documentation. Pregnant or nursing women were not enrolled. Exclusion criteria included frank arthritis or objective evidence of central nervous system or cardiac (second- or third-degree block) involvement at time of presentation; evidence of meningismus or Bell palsy with pleocytosis [more than 7 cells/mm3]; and history of 1) nervous system, cardiac, rheumatic, or collagen vascular disease, 2) an immediate hypersensitivity reaction to -lactam antibiotics or macrolides, 3) any antibiotic therapy within 72 hours before enrollment or use of any antibiotic during the study other than those supplied, or 4) antibiotic treatment for Lyme disease during the preceding 12 months. The study protocol was approved by the Institutional Review Board of each study center, and all participants gave written informed consent. Clinical Diagnostic Evaluations Patients were evaluated by a physician at baseline and 8, 20, 30, 90, and 180 days after initiation of therapy. Subjective symptom scores for 11 key symptoms (fatigue, joint pain, headache, muscle pain, anorexia, stiff neck, fevers, paresthesias, dizziness, cough, and nausea and vomiting) were recorded on a visual analog scale at each evaluation. Blood samples were obtained for B. burgdorferi serologic testing (IgG and IgM), hepatitis B serologic tests, and liver function tests. Electrocardiography was done. All tests except for the hepatitis B serologic test were repeated on days 8, 20, and 30. In addition, blood samples for B. burgdorferi serologic testing and electrocardiograms were obtained at the 90- and 180-day evaluations. All ELISAs for Lyme disease were done at the University of Minnesota as previously described [8]. Patients were seen at unscheduled visits if indicated by their clinical condition. Treatment and Study Design Patients were stratified by the presence of flu-like constitutional symptoms (such as fever, chills, headache, malaise, fatigue, arthralgias, and myalgias) and then randomly assigned to one of the two treatment arms. Each center was given a randomization schedule for two types of presenting symptoms: erythema migrans alone and erythema migrans with flu-like symptoms. These randomization schedules consisted of sequential numbers to which the following study drug regimens were allocated: 500 mg of azithromycin once daily and placebo doses twice daily (to match the three-times-daily dosing regimen of amoxicillin); or amoxicillin, 500 mg three times daily. The drugs were provided by Pfizer Central Research in a double-matching (dummy) form so that all pills for both groups of patients were identical. All patients received the oral (active or placebo) medication for 20 days, but those in the azithromycin group received active drug for only 7 days. Both the clinical investigator and the patient were blinded to treatment assignments. Efficacy was evaluated in the patients who returned for an examination on day 20 and had taken at least one half of their medication. Patients who withdrew from the study because of adverse events and who took less than one half of their medication were considered nonevaluable for efficacy analysis. Response was assessed by clearance or persistence of erythema migrans and presenting objective signs and by relief of symptoms (assessed using the visual analog scale), and was then graded according to the following criteria. 1. Complete response: complete clearance of erythema migrans and all objective signs and greater than 75% relief of presenting symptoms. 2. Partial response: 1) complete clearance of erythema migrans with persistent signs and 50% to 75% relief of symptoms or 2) persistent erythema migrans with complete clearance of signs and greater than 75% relief of symptoms. 3. Treatment failure: 1) persistent erythema migrans, persistent signs, and less than 50% relief of symptoms or 2) development of new signs and symptoms of disease before the examination on day 20. Symptom relief was calculated as a percent reduction from baseline in the sum of the symptom scores on the visual analog scale. On subsequent examinations up to 180 days, patients were evaluated for relapse, which was defined as any objective evidence of arthritis, evanescent skin lesions, facial palsies, atrioventricular heart block, or peripheral or central nervous system disease, including meningitis. Toleration of treatment was determined from treatment-related adverse events and laboratory abnormalities. Statistical Analysis To compare responses to therapy, we used chisquare analysis or the Fisher exact test (two-tailed) for ordinal data and the t-test (two-tailed) for interval data. Confidence intervals on percentages were calculated using a normal approximation with are sine transformation. Results Study Population The baseline demographic and clinical characteristics of the patients are shown in Table 1. The mean diameter of the largest erythema migrans lesion, the distribution of single and multiple erythema migrans lesions, the presence of concomitant flu-like illness, and the seropositivity rate did not differ significantly between the treatment groups. The baseline characteristics were similar, except that the azithromycin group had more patients with multiple erythema migrans lesions. Table 1. Baseline Demographic and Clinical Characteristics of Evaluable Patients On physical examination at study entry, the most common signs of disease included lymphadenopathy (18%; lymphadenopathy was regional in 40 patients and generalized in 3), pain on neck flexion (13%), muscle tenderness (12%), and joint tenderness (11%) (Table 2). Of the 11 self-reported symptoms, the most frequent were fatigue (52%), joint pain (34%), headache (29%), muscle pain (26%), anorexia (24%), fever (22%), and stiff neck (21%) (Table 2). Electrocardiographic abnormalities (first-degree block) attributed to Lyme disease were present in four patients (2%); none had cardiac abnormalities by day 20. Although one patient, who had first-degree heart block, had a relapse (joint pain) at 180 days, his electrocardiogram continued to be normal. Mild liver function abnormalities were noted in more than 20% of patients; increases in aminotransferase levels occurred most frequently. Table 2. Clinical Manifestations of Erythema Migrans in Evaluable Patients Of the 246 patients enrolled, 217 (88%) were evaluable for efficacy at day 20. Seven patients (2 receiving azithromycin and 5 receiving amoxicillin) were excluded because they had received less than 50% of their study medication as a result of adverse events; 17 patients (8 receiving azithromycin and 9 receiving amoxicillin) did not return for the follow-up examination at day 20; 2 patients (both receiving amoxicillin) were noncompliant; and 3 patients (all receiving azithromycin) did not meet entry criteria. The baseline signs of disease in the nonevaluable patients were regional lymphadenopathy (9 patients [31%]), muscle tenderness (1 patient [3%]), neck pain (2 patients [7%]), pharyngitis (4 patients [14%]), evanescent erythema migrans (3 patients [10%]), right upper quadrant tenderness (1 patients [3%]), and first-degree atrioventricular block (1 patient [3%]). The baseline symptoms of these patients were fatigue (13 patients [45%]), joint pain (8 patients [28%]), headache (7 patients [24%]), muscle pain (7 patients [24%]), anorexia (5 patients [17%]), stiff neck (11 patients [38%]), fever (4 patients [14%]), paresthesia (4 patients [14%]), dizziness (3 patients [10%]), and cough (2 patients [7%]). Response to Therapy Twenty days after the initiation of therapy, 93 of 106 patients treated with amoxicillin (88% [95% CI, 80% to 93%]) had had a complete response to therapy compared with 84 of 111 patients treated with azithromycin (76% [CI, 67% to 83%]) (P = 0.024) (Table 3). Furthermore, 3 patients treated with azithromycin had not responded or had worsened within the first 20 days (for example, they had persistent erythema migrans, joint tenderness,

Treatment of early lyme disease

PURPOSE To compare the safety and efficacy of azithromycin, amoxicillin/probenecid, and doxycycline for the treatment of early Lyme disease, to identify risk factors for treatment failure, and to describe the serologic response in treated patients. PATIENTS AND METHODS Fifty-five patients with erythema migrans and two patients with flu-like symptoms alone and fourfold changes in antibody titers to Borrelia burgdorferi were randomized to receive (1) oral azithromycin, 500 mg on the first day followed by 250 mg once a day for 4 days; (2) oral amoxicillin 500 mg and probenecid 500 mg, three times a day for each for 10 days; or (3) doxcycline, 100 mg twice a day for 10 days. If symptoms were still present at 10 days, treatment was extended with amoxicillin/probenecid or doxycycline for 10 more days. Evaluations were done at study entry and 10, 30, and 180 days later. RESULTS Three of the patients who initially had symptoms suggestive of spread of the spirochete to the nervous system, one from each antibiotic treatment group, subsequently developed neurologic abnormalities, but symptoms in the other 54 patients resolved within 3 to 30 days after study entry. Six of the 19 patients (32%) (95% confidence interval, 13% to 57%) given amoxicillin/probenecid developed a drug eruption, whereas none of the patients given azithromycin or doxycycline had this complication. The presence of dysesthesias at study entry was the only risk factor significantly associated with treatment failure (p less than 0.001). By convalescence, 72% of the patients were seropositive, and 56% still had detectable IgM responses to the spirochete 6 months later. CONCLUSIONS The three antibiotic regimens tested in this study were generally effective for the treatment of early Lyme disease, but the regimens differ in the frequency of side effects and in ease of administration.

In vitro and in vivo susceptibility of the Lyme disease spirochete, Borrelia burgdorferi, to four antimicrobial agents.

The antimicrobial susceptibility of Borrelia burgdorferi isolated from human spinal fluid was determined in vitro and in vivo. A broth dilution technique was used to determine the MBCs of four antimicrobial agents. The Lyme disease spirochete was most susceptible to ceftriaxone (MBC, 0.04 microgram/ml) and erythromycin (MBC, 0.05 microgram/ml), then tetracycline (MBC, 0.8 microgram/ml), and finally penicillin G (MBC, 6.4 micrograms/ml). Syrian hamsters were used to determine the 50% curative doses (CD50s) of the four antimicrobial agents. Ceftriaxone and tetracycline had the highest activities, with CD50s of 24.0 and 28.7 mg/kg [corrected], respectively. Both erythromycin and penicillin G possessed low activities. The CD50 of erythromycin was 235.3 mg/kg [corrected], and the CD50 of penicillin G was greater than 197.5 mg/kg [corrected].

Bloodstream Invasion in Early Lyme Disease: Results From A Prospective, Controlled, Blinded Study Using the Polymerase Chain Reaction

PURPOSE : The purposes of this study were to determine (1) the optimal techniques for and potential diagnostic usefulness of the polymerase chain reaction (PCR) in early Lyme disease, and (2) the true frequency and clinical correlates of PCR-documented blood-borne infection in the dissemination of Lyme disease. PATIENTS AND METHODS : We performed a prospective, controlled, blinded study of PCR, culture, and serology on fractionated blood samples from 105 patients ; 76 with physician-diagnosed erythema migrans and 29 controls. Clinical characteristics of the patients were obtained with a standardized data entry form and correlated with results of the laboratory studies. RESULTS : Only 4 of the 76 (5.3%) patients with erythema migrans were culture positive ; however, 14 of 76 (18.4%) had spirochetemia documented by PCR of their plasma. None of 29 controls were PCR or culture positive (P = 0.007, versus patients). PCR-documented spirochetemia correlated with clinical evidence of disseminated disease ; 10 of 33 patients (30.3%) with systemic symptom(s) were PCR positive compared to 4 of 43 (9.3%) without such evidence (P = 0.02). PCR positivity was more frequent among patients with each of four specific symptoms : fever, arthralgia, myalgia, and headache (all P <0.05). A higher total number of symptoms (median 2.5 in PCR-positive patients versus O in PCR-negative controls ; P <0.01) and the presence of multiple skin lesions (37.5% of patients with multiple, versus 13.3% of patients with single lesions [P = 0.04]) were also correlated with PCR positivity. Patients with both systemic symptoms and multiple skin lesions had a 40% PCR-positivity rate ; however, 4 of 42 (9.5%) asympatomatic patients with only single erythema migrans lesions were also PCR positive. In multivariate analysis using logistic regression, the number of systemic symptoms was the strongest independent predictor of PCR positivity (P = 0.004). CONCLUSIONS : PCR detection of Borrelia burgdorferi is at least three times more sensitive than culture for identifying spirochetemia in early Lyme disease and may be useful in rapid diagnosis. PCR positivity significantly correlates with clinical evidence of disease dissemination. Bloodstream invasion is an important and common mechanism for the dissemination of the Lyme disease spirochete.

SPIROCHETES IN TICKS AND ANTIBODIES TO BORRELIA BURGDORFERI IN WHITE-TAILED DEER FROM CONNECTICUT, NEW YORK STATE, AND NORTH CAROLINA

Ticks were screened for spirochetes and serum samples from white-tailed deer (Odocoileus virginianus) were assayed for antibodies to Borrelia burgdorferi during 1983–1984. Using fluorescein isothiocyanate-labeled rabbit antibodies produced to B. burgdorferi, the etiologic agent of Lyme disease, spirochetes were detected in Ixodes dammini (10.5% of 1,193) and Dermacentor albipictus (0.6% of 157) adults from Connecticut, I. dammini nymphs (49.1% of 108) and adults (64.7% of 99) from Armonk, New York, and in I. scapularis (0.4% of 531) and Amblyomma americanum (3.5% of 173) adults from North Carolina. Infected ticks were either seeking hosts or feeding on deer during the summer and fall. Direct fluorescent antibody staining also revealed spirochetes in two larvae of I. scapularis that emerged from eggs deposited by separate females in the laboratory. Using indirect immunofluorescence tests, antibodies to B. burgdorferi were identified in white-tailed deer living in tick-infested areas of all three states. Aside from minor cross-reactivity, there was no serologic evidence of Treponema or Leptospira infections. Ixodes dammini is a primary vector of B. burgdorferi in northeastern United States, but in North Carolina, other ixodid ticks may transmit this spirochete to humans and wildlife.

A case-control study to assess possible triggers and cofactors in chronic fatigue syndrome**

PURPOSE To assess possible triggers and cofactors for chronic fatigue syndrome (CFS) and to compare levels of selected cytokines between cases and an appropriately matched control group. PATIENTS AND METHODS We conducted a case-control study of 47 cases of CFS obtained through a regional CFS research program maintained at a tertiary care medical center. One age-, gender-, and neighborhood-matched control was identified for each case through systematic community telephone sampling. Standardized questionnaires were administered to cases and controls. Sera were assayed for transforming growth factor-beta (TGF-beta), interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and antibody to Borrelia burgdorferi and Babesia microti. RESULTS Cases were more likely to have exercised regularly before illness onset than controls (67% versus 40%; matched odds ratio (MOR) = 3.4; 95% CI = 1.2 to 11.8; P = 0.02). Female cases were more likely to be nulliparous prior to onset of CFS than controls (51% versus 31%; MOR = 8.0; 95% CI = 1.03 to 170; P = 0.05). History of other major factors, including silicone-gel breast implants (one female case and one female control), pre-morbid history of depression (15% of cases, 11% of controls) and history of allergies (66% of cases, 51% of controls) were similar for cases and controls. However, cases were more likely to have a diagnosis of depression subsequent to their diagnosis of CFS compared to a similar time frame for controls (MOR = undefined; 95% CI lower bound = 2.5; P < 0.001). Positive antibody titers to B burgdorferi (one case and one control) and B microti (zero cases and two controls) were also similar. CONCLUSIONS Further investigation into the role of prior routine exercise as a cofactor for CFS is warranted. This study supports the concurrence of CFS and depression, although pre-morbid history of depression was similar for both groups.

The Persistence of Spirochetal Nucleic Acids in Active Lyme Arthritis

Lyme disease, caused by the spirochete Borrelia burgdorferi, is a common tick-borne infection. Arthritis develops in approximately one half of untreated patients who have a history of erythema migrans [1] and occurs, albeit rarely, even after treatment [2]. Spirochetes have rarely been cultivated from synovial fluid [3, 4] but have been noted near blood vessels in silver-stained sections from synovectomy specimens [5]. Because it is difficult to find spirochetes in affected joints, the host response [6-8] and specific class II immune response genes [9] have been suggested as major determinants in the pathogenesis of arthritis. The general failure to recover spirochetes, however, does not exclude a primary role for B. burgdorferi in initiating and maintaining the arthritic process. The polymerase chain reaction (PCR) is capable of detecting low numbers of organisms [10, 11]. Although we (unpublished data) and others [12] retrospectively detected B. burgdorferi DNA by PCR in stored synovial fluid, the extreme sensitivity of the PCR makes contamination of such samples and false-positive results a potential problem. Therefore, to test the hypothesis that noncultivatable B. burgdorferi persists in Lyme arthritis, we did controlled, prospective culture and PCR studies on synovial fluid from patients with Lyme arthritis. Methods Samples from patients and controls were obtained over a 10-month period from both the university hospital and from clinicians in Minnesota and Wisconsin, areas where the background seroprevalence of B. burgdorferi among healthy individuals is 1% to 2%. Lyme arthritis was suspected in patients with mono- or oligoarticular large joint involvement, seropositivity for B. burgdorferi, and no other known underlying disease. Controls were from the same areas. They presented with various arthritic processes (see Results) and were having arthrocentesis of involved joints. Synovial fluid was processed in a building where B. burgdorferi had never been cultivated. Synovial fluid (0.5 to 1.0 mL) was centrifuged at 16 000 g for 15 minutes, and the pellet was resuspended in 200 L of supernatant fluid. One half was used for PCR, and the other was cultured as described previously [13] but with 0.1% agar. Nucleic acids were guanidium isothiocyanate-extracted and subjected to PCR [10] using primers 991 and 992 corresponding to nucleotides 16-43 and 222-247, respectively, of a chromosomal sequence that amplifies 231 bp of B. burgdorferi DNA [10]. The PCR products were subjected to electrophoresis in agarose and transferred to nylon membranes. A 167-bp digoxigenin-11-deoxyuridine triphosphate probe (nucleotides 81-247, reference [10]) was used for Southern hybridization as specified by the manufacturer (GENIUS kit, Boehringer-Mannheim, Indianapolis, Indiana). Confirmation studies used two different primer pairs (A2, A4 and A149, A319) and internal probes for the plasmid-encoded B. burgdorferi outer surface protein A gene [11]. Study personnel were blinded to the suspected disease for all but one patient sample. Immunoglobulin G antibody against B. burgdorferi was measured by enzyme immunoassay with seropositivity defined as optical density values 3 standard deviations above the mean for 200 blood donors. Results Synovial fluid from six of seven (86%; 95% CI, 42% to 100%) persons thought to have Lyme arthritis was positive by PCR for B. burgdorferi DNA. Results from three of these (samples 5, 8, and 12) are shown (Figure 1). Results of the following tests were negative for all seven patients: rheumatoid factor, antinuclear antibodies, examinations for crystals, and aerobic and anaerobic cultures. All cultures for B. burgdorferi were negative. Figure 1. Southern blot of polymerase chain reaction (PCR)-amplified samples from patients and controls. B. burgdorferi top left bottom left Case Histories Sample 5 A 42-year-old man with erythema migrans was treated with oral tetracycline for 2 weeks, and the rash resolved. Six years later, he developed knee pain and swelling, was found to be B. burgdorferi seropositive, and was treated with oral doxycycline for 3 months without improvement. After 2 months of treatment, synovial fluid showed a leukocyte count of 16.7 109/L (79% granulocytes) and was positive for B. burgdorferi by PCR. He was treated with intravenous ceftriaxone for 8 weeks, and symptoms resolved. Sample 8 A 30-year-old woman reported 4 months of knee pain and swelling and was seropositive for B. burgdorferi. A synovial fluid specimen showed a leukocyte count of 37.8 109/L (95% granulocytes) and was PCR positive. She was treated with oral doxycycline for 3 months, and symptoms resolved. Sample 12 A 20-year-old man developed bilateral facial nerve palsies and lymphocytic meningitis. One year later, he developed fatigue, knee pain and swelling, and B. burgdorferi seropositivity. He received oral doxycycline therapy for 3 months and showed partial improvement. One month later, a large effusion developed and he had difficulty in walking; a synovial fluid sample showed a leukocyte count of 12.8 109/L (90% granulocytes) and was positive for B. burgdorferi by PCR. Another specimen (sample 11), obtained 2 months later while the patient was receiving another course of doxycycline, showed a leukocyte count of 2.7 109/L (only 15% granulocytes) and was negative by PCR. Other Samples (not shown) Sample 16: A 36-year-old man had knee pain and swelling and was seropositive for B. burgdorferi. Synovial fluid analysis showed a leukocyte count of 8.0 109/L (predominantly granulocytes) and a positive PCR test result. He received oral doxycycline for 2 months, and symptoms resolved. Sample 22: A 54-year-old woman had knee pain and effusion and was seropositive for B. burgdorferi. A synovial fluid specimen showed a leukocyte count of 54.1 109/L (87% granulocytes). She is improving with oral doxycycline. Sample 25: A 28-year-old man had tick exposures, no history of rash, and unexplained fevers with myalgias 16 months before the sample was taken. For 1 year he experienced worsening monthly episodes of arthritis of the knee, and he became seropositive for B. burgdorferi. Physical examination showed elbow, knee and ankle effusions. A synovial fluid specimen from the knee showed a leukocyte count of 26.8 109/L (82% granulocytes) and was positive by PCR. He is currently receiving doxycycline. One PCR-negative sample (sample 1) was obtained from a seropositive patient who was treated for probable chronic Lyme arthritis. This patient had an unexplained febrile illness several months before arthritis of the knee developed. After treatment with oral penicillin for 3 months and intravenous penicillin for 1 month, symptoms resolved. Five and 7 years later, arthritis recurred and the patient responded to intravenous penicillin and oral doxycycline, respectively. Synovial fluid obtained after the last treatment course showed a leukocyte count of 5.9 109/L (all lymphocytes). Summary Six of seven patients with Lyme arthritis were positive by PCR. In contrast, all 18 synovial fluid samples from patients with other disorders, including rheumatoid arthritis, spondyloarthropathy, gout, pseudogout, hemarthrosis, degenerative joint disease, lupus, papillary synovitis, and trauma, were negative by PCR (P < 0.001, Lyme arthritis compared with controls, Fisher exact test). All 38 laboratory controls were negative by PCR. The assay reproducibly detected 20 or fewer B. burgdorferi cells directly or when added to extracted synovial fluid that was previously negative by PCR. Polymerase chain reaction was done four times with identical results, including analyses with both outer surface protein A primer sets. Discussion Six of 7 prospectively studied patients with Lyme arthritis had spirochetal nucleic acids present in affected joints, despite negative cultures. The fastidious techniques, the many controls with negative PCR results, and the confirmation of results with both chromosomal and plasmid targets make us confident there were no false-positive test results. Detection of organisms when PCR-negative samples were spiked assures against false-negative test results. The number of organisms or equivalents detected by PCR was high in several patients (103/mL to 104/mL). Thus, the failure to cultivate spirochetes was not always caused by insufficient numbers. The discrepancy between PCR results and culture results suggests that organisms present could be injured, dead, or otherwise inhibited from multiplication, a situation that may help explain why some patients have apparent clinical resistance to antimicrobial agents. Our results show the intra-articular persistence of B. burgdorferi nucleic acids in Lyme arthritis and suggest that persistent organisms and their components are important in maintaining ongoing immune and inflammatory processes even among some antibiotic-treated patients. Further studies are needed to determine the microbiologic state of these organisms and their therapeutic and prognostic implications. Grant support: By NIH grants AR40448 and AI29739.

Experimental infection of the hamster with Borrelia burgdorferi.

The origin of the strains of Borrelia burgdorferi used in this study were strain 297, a human spinal fluid isolate (Allen Steere, Yale University, New Haven, CT); P/Bi, a human spinal fluid isolate and P/Gu, a human skin isolate (Vera Preac-Mursic, Max von Petenkofer-Institut, Munich, FRG); MM, Minnesota mouse (University of Minnesota, Minneapolis, MN); IPT, Zxodes pacijkus tick (Robert Lane, University of California, Berkeley, CA). The spirochetes were cultured in Barbour-Stoenner-Kelly (BSK) medium2 at 30OC. Medium for the isolation of spirochetes from animals was prepared by the addition of 0.15% agarose (SeaKem LE, FMC Corp., Marine Colloids Division, Rockland, ME) to the BSK medium.

Comparative in vitro and in vivo susceptibilities of the Lyme disease spirochete Borrelia burgdorferi to cefuroxime and other antimicrobial agents.

The in vitro and in vivo susceptibilities of the Lyme disease pathogen Borrelia burgdorferi to cefuroxime were compared with those of several other antibiotics commonly used to treat this disease. Cefuroxime demonstrated a higher MBC in vitro (1.0 microgram/ml) than ceftriaxone (0.08 microgram/ml) or erythromycin (0.32 microgram/ml), but the MBC was similar to that of amoxicillin (0.8 microgram/ml) and doxycycline (1.6 micrograms/ml). B. burgdorferi was considerably less susceptible to tetracycline (3.2 micrograms/ml) and penicillin G (6.4 micrograms/ml). Of the three other Borrelia species tested, two (Borrelia turicatae and Borrelia anserina) also demonstrated susceptibility to cefuroxime, while the third (Borrelia hermsii) was less susceptible. Results obtained with four antimicrobial agents in the in vivo hamster model parallel the antibiotic susceptibilities in the in vitro study. The three antibiotics with similar MBCs in vitro, i.e., cefuroxime, doxycycline, and amoxicillin, demonstrated comparable activities in preventing borreliosis in B. burgdorferi-challenged hamsters (50% curative doses = 28.6, 36.5 and 45.0 mg/kg, respectively). Penicillin G, which demonstrated the highest MBC in vitro, had very weak protective activity in the hamster model system. These results indicate that the in vitro and in vivo activities of cefuroxime against B. burgdorferi are comparable to those of several oral antibiotics currently being used in the treatment of early Lyme disease and suggest that the oral form of this cephalosporin may be an effective alternative therapy for this disease.