The persistence of Borrelia burgdorferi in patients treated with antibiotics is described. The diagnosis of Lyme disease is based on clinical symptoms, epidemiology and specific IgG and IgM antibody titers to B. burgdorferi in serum. Antibiotic therapy may abrogate the antibody response to the infection as shown in our patients. B. burgdorferi may persist as shown by positive culture in MKP-medium; patients may have subclinical or clinical disease without diagnostic antibody titers to B. burgdorferi. We conclude that early stage of the disease as well as chronic Lyme disease with persistence of B. burgdorferi after antibiotic therapy cannot be excluded when the serum is negative for antibodies against B. burgdorferi.

bWith the increasing prevalence of multidrug-resistant Gram-negative bacteria, rapid identification of the pathogen and its individual antibiotic resistance is crucial to ensure adequate antiinfective treatment at the earliest time point. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for the identification of bacteria directly from the blood culture bottle has been widely established; however, there is still an urgent need for new methods that permit rapid resistance testing. Recently, a semiquantitative MALDI-TOF mass spectrometry-based method for the prediction of antibiotic resistance was described. We evaluated this method for detecting nonsusceptibility against two ␤-lactam and two non-␤-lactam antibiotics. A collection of 30 spiked blood cultures was tested for nonsusceptibility against gentamicin and ciprofloxacin. Furthermore, 99 patient-derived blood cultures were tested for nonsusceptibility against cefotaxime, piperacillin-tazobactam, and ciprofloxacin in parallel with MALDI-TOF mass spectrometry identification from the blood culture fluid. The assay correctly classified all isolates tested for nonsusceptibility against gentamicin and cefotaxime. One misclassification for ciprofloxacin nonsusceptibility and five misclassifications for piperacillin-tazobactam nonsusceptibility occurred. Identification of the bacterium and prediction of nonsusceptibility was possible within approximately 4 h. The early initiation of adequate antibiotic therapy is known to be an important parameter for the outcome of septic patients (1-3). Therefore, empirical treatment must be administered as soon as sepsis is diagnosed; however, with the growing burden of antimicrobial resistance, affecting the sepsis-causing pathogen with an empirical therapy is becoming increasingly difficult. Prediction of antibiotic resistance at the earliest time point is necessary to ensure the best available treatment for the patient and to avoid the extensive use of broad-spectrum therapy. One approach to shorten the time to result for antibiotic susceptibility testing (AST) is the use of matrix-assisted laser desorption ionizationtime of flight mass spectrometry (MALDI-TOF MS) for identification and resistance testing. The most common approach using mass spectrometry is the detection of ␤-lactamases with a functional assay that measures their hydrolysis products (4-9). This test provides results within 1 to 3 h, but, by its very nature, it is limited to the detection of ␤-lactamase-mediated resistance. Recently, Lange et al. (10) described a MALDI-TOF MS method that allows for resistance testing independent of the underlying mechanism. The MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA) relies on a semiquantitative measurement of bacterial proteins. Bacterial cells are incubated in culture medium with or without antibiotics. Subsequently, the cells are lysed and spiked with an internal standard. Mass spectra from the two setups are acquired and normalized, and their peak intensit...

The in vitro and in vivo activity of the new macrolides azithromycin, clarithromycin and roxythromycin was compared with that of erythromycin against Borrelia burgdorferi. In in vitro tests using ten clinical isolates all macrolides were highly active against Borrelia burgdorferi (MIC90 0.015-0.06 micrograms/ml). Azithromycin was more potent than the other macrolides in experimental animal infection, eradicating the organism in all animals tested at a dosage of 8 mg/kg.

Gerbils appear to be susceptible to infection by human isolates of Borrelia burgdorferi; we obtained 100% infection. Isolation of the B. burgdorferi from different organs six months post infection causes a generalized infection thus demonstrating that borreliae persist in these animals for a long period. Spirochetemia was present for 14 days, apparently in two intervals. The Borrelia burgdorferi specific antibody titers increased with time after infection thus indicating the persistence of spirochetes. The intraperitoneal inoculation of the B. burgdorferi to six gerbils of groups A and B induced significant histopathologic changes in most of the major organ systems and their surrounding adipose and fibrous connective tissues. The infiltrates consisted mainly of lymphocytes and histiocytes. Various numbers of plasma cells, eosinophils and high numbers of mast cells were also present. Three further animals which served as controls displayed no histological signs of inflammation in any organ system. No significant differences were noted between the histopathological findings seen in the animals of groups A and B (infected with cells from subcultures no. 25 and with no. 5, respectively). The persistence of B. burgdorferi and the high number of organs involved with slight to severe signs of inflammation in this series can be compared to persistence and to the multiorgan involvement seen in human Lyme disease. Thus gerbils can serve as suitable experimental animals to study the pathogenesis of Lyme disease and the extent of organ damage caused by B. burgdorferi.

Fig. 2 Circular dichroism spectra of the enantiomers 1-5: (a) 1, (b) 2, (c) 3, (d) 4 and (e) 5. -First eluted enantiomer. -Second eluted enantiomer.