In Vitro Susceptibility Testing of Borrelia burgdorferi Sensu Lato Isolates Cult

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In Vitro Susceptibility Testing of Borrelia burgdorferi Sensu Lato

Isolates Cultured from Patients with Erythema Migrans before and after

Antimicrobial Chemotherapy

Klaus-Peter Hunfeld, Eva Ruzic-Sabljic, Douglas E. Norris, Peter Kraiczy,

and Franc Strle.

 

_http://aac.asm.org/cgi/content/full/49/4/1294_

(http://aac.asm.org/cgi/content/full/49/4/1294)

 

Clinical treatment failures have been reported to occur in early Lyme

borreliosis (LB) for many suitable antimicrobial agents. Investigations of

possible resistance mechanisms of the Borrelia burgdorferi complex must analyze

clinical isolates obtained from LB patients, despite their receiving

antibiotic treatment. Here, borrelial isolates obtained from five patients with

erythema migrans (EM) before the start of antibiotic therapy and again

after the conclusion of treatment were investigated. The 10 isolates were

characterized by restriction fragment length polymorphism analysis and plasmid

profile analysis and subjected to susceptibility testing against a variety

of antimicrobial agents including those used for initial chemotherapy. Four

out of five patients were infected by the same genospecies (Borrelia

afzelii, n = 3; Borrelia garinii, n = 1) at the site of the EM lesion before

and

after antimicrobial therapy. In one patient the genospecies of the initial

isolate (B. afzelii) differed from that of the follow-up isolate (B.

garinii). No significant changes in the in vitro susceptibilities became

obvious

for corresponding clinical isolates before the start and after the

conclusion of antimicrobial therapy. This holds true for the antimicrobial

agents

used for specific chemotherapy of the patients, as well as for any of the

additional agents tested in vitro. Our study substantiates borrelial

persistence in some EM patients at the site of the infectious lesion despite

antibiotic treatment over a reasonable time period. Borrelial persistence,

however, was not caused by increasing MICs or minimal borreliacidal

concentrations in these isolates. Therefore, resistance mechanisms other than

acquired

resistance to antimicrobial agents should be considered in patients with LB

resistant to treatment