## 9 Evidence from Isolates from Patients and Primates with Spirochetal Persistence  
Treating LB with amoxicillin, cefuroxime, ceftriaxone and tetracycline is a common way to successfully resolve the infection [7; 16; 144; 145]. However, similar to antibiotic treatment failures in patients with syphilis, another form of spirochetal infection [146], cases of treatment failure have been reported for almost every antimicrobial agent recommended for treating LB [7; 18; 19; 20; 21; 22; 82; 147; 148; 149; 150; 151]. The occurrence of spirochetal persistence in EM patients has already been demonstrated in clinical studies [63]. Following these observations, \begin{table}
\begin{tabular}{c c c c c c} \hline
**Spot** & \(p\)**l** & **Mol. Mass (kDa)** & **Up- or Down** & **Mol. Mass (kDa)** & **Identified Protein** \\ \hline  & **(Est. from Gel)** & **(Est. from Gel)** & **Regulation** & **(From Database)** & **(By MALDI TOF MS)** \\ \hline P-2702 & 5.9 & 65 & d & 86.13 & Membrane-associated protein & P66 (BB0603) \\ P-3703 & 6.2 & 65 & d & 68.13 & Membrane-associated protein & P66 (BB0603) \\ P-4702 & 6.4 & 63 & d & 63.496 & Ribosomal protein S1 (RpsA) \\  & & & & & (BB0127) \\ P-4706 & 6.7 & 63 & d & NA & No match found \\ P-4802 & 6.4 & 75 & d & NA & No match found \\ P-4803 & 6.5 & 75 & d & 80.298 & Polyribonucleotide \\  & & & & & nucleotidyltransferase (PnpA) \\  & & & & & (BB0805) \\ P-4804 & 6.6 & 75 & d & NA & No match found \\ P-5702 & 7 & 57 & d & 50.061 & Pyrophosphate-fructose-6-phosphate-1-phosphotransferase \\  & & & & & (Pfp) \\  & & & & & (BB0727) \\ P-7103 & 8.1 & 25 & d & 30.417 & Predicted coding region \\  & & & & (BB0238) \\ P-7602 & 7.8 & 50 & d & 55.856 & Glycerol kinase (GlyK) \\  & & & & & (BB0241) \\ P-7603 & 7.9 & 49 & d & 53.227 & Pyruvate kinase (Pyk) \\  & & & & & (BB0348) \\ D/P-4703 & 6.5 & 65 & d & NA & No match found \\ D/P-4705 & 6.6 & 63 & d & NA & No match found \\ D/P-7001 & 7.9 & 23 & d & 26.569 & Pfs protein (Pfs-1) \\  & & & & & (BB0375) \\ D-0504 & 5.2 & 42 & d & 42.372 & Cell division protein (FtsZ) \\  & & & & & (BB0229) \\ D-4101 & 6.4 & 26 & u & 27.984 & Triosephosphate isomerase \\ \hline  & & & Proteins were identified by MALDI TOF MS after preparative isolation from 2-DE gels. \(p\)l: isoelectric point; P: proteins affected by penicillin G exposure; D: proteins affected by doxycycline exposure; NA: not available. d: down-regulated; u: up-regulated. \\ \end{tabular}
\end{table} 
Table 3: Protein spots and proteins showing up- or down-regulation after exposure to _B. burgdorferi_ s.s. strain LW2 to increasing concentrations of penicillin G, doxycycline, or both (mod. from [129]). additional experiments investigated the individual in vitro susceptibilities of 10 clinical isolates obtained from five EM patients before and after chemotherapy (Table 4) [7]. In this unique study, the total number of individuals with persistent infection after the conclusion of chemotherapy accounted for 1.7% of culture-confirmed EM patients (N = 1148) seen from 1995 to 2000 at the LB outpatient clinic at the University Clinic in Ljubljana, Slovenia [7]. The results of molecular typing clearly substantiate that all but one patient with a positive follow-up culture remained persistently infected with the same _Borrelia_ genospecies at the same peripheral location for several weeks despite antibiotic treatment [7; 60]. All isolates were then tested under standardized conditions using the previously described colorimetric MIC method, and MBC values were determined in modified BSK medium using conventional subculture approaches [7; 17]. Overall, _B. garini_ isolates tended to be more susceptible than _B. afzelli_ isolates that had higher MIC and MBC values [7]. Testing of clinical isolates obtained from the same patient before the start and after the conclusion of antimicrobial therapy for EM did not reveal clinically significant differences, i.e., no increase or decrease for \(\geq\)2 log\({}_{2}\) unit dilutions in the median MICs and MBCs [7].