A number of modified microdilution susceptibility testing methods using BSK medium have been developed over the years. In some tests, MIC values are measured by exposing an inoculum with a final density of ~105 borreliae/mL, as determined in a Neubauer counting chamber, to logarithmic dilutions of antimicrobial agents. Sterile 96-well microtitre plates with the inclusion of positive and negative growth controls are used. The plates are then inoculated under sterile conditions before being sealed with adhesive plastic and incubated at 33 ◦C under anaerobic conditions for 72 h. Following incubation, dark-field microscopy is used to examine all wells for spirochete counts, morphology and motility. Here, the MIC is commonly defined as the lowest concentration of an antimicrobial agent at which no motile or only very slightly motile spirochetes are observed in significantly reduced numbers using dark-field microscopy. Antimicrobial agents are normally tested in triplicate. MIC values, in which 50% (MIC50) and 90% (MIC90) of isolates are inhibited, are determined for each antibiotic used on the isolates tested. However, such experiments are laborious and MIC determination can be very imprecise as it highly depends on the individual investigator. Unfortunately, no internationally accepted standardized MIC breakpoints for antimicrobial agents currently exist for Borrelia spp.
Author(s) Details:
Klaus-Peter Hunfeld
Institute for Laboratory Medicine, Microbiology & Infection Control, Northwest Medical Centre, Academic Teaching Hospital, Medical Faculty, Goethe-University Frankfurt, Steinbacher Hohl 2-26, D-60488 Frankfurt am Main, Germany and INSTAND e.V., Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien e.V.,Ubierstraße 20, D-40223 Düsseldorf, Germany.
Peter Kraiczy
Institute for Medical Microbiology & Infection Control, University Hospital Frankfurt, Goethe-University Frankfurt, Paul-Ehrlich Str. 40, D-60596 Frankfurt am Main, Germany.
Douglas E. Norris
W. Harry Feinstone Department of Molecular Microbiology & Immunology, Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St, Baltimore, MD 21205, USA.
Benedikt Lohr
Institute for Laboratory Medicine, Microbiology & Infection Control, Northwest Medical Centre, Academic Teaching Hospital, Medical Faculty, Goethe-University Frankfurt, Steinbacher Hohl 2-26, D-60488 Frankfurt am Main, Germany.
Recent Global Research Developments in Understanding Borrelia burgdorferi Sensu Lato: An Overview
Global Seroprevalence and Sociodemographic Characteristics of Bb in Human Populations:
A systematic review and meta-analysis investigated Bb seroprevalence worldwide [1].
The estimated global Bb seroprevalence was approximately 14.5%.
Top regions with Bb seropositivity were Central Europe (20.7%), Eastern Asia (15.9%), and Western Europe (13.5%).
Factors associated with Bb seropositivity included age ≥50 years, male gender, rural residence, and tick bites.
Using Western blotting (WB) confirmation improved accuracy in Bb antibody detection.
Transmission of Bb Sensu Lato Complex:
Lyme borreliosis involves several Bb species maintained in complex networks involving ticks and reservoir hosts.
Climate influences vector and host habitats, impacting their ecology [2].
Lyme Borreliosis Burden:
While no consensus exists on global Bb prevalence, Northern Hemisphere residents face the highest Lyme borreliosis burden [1].
References
- Dong, Y., Zhou, G., Cao, W., Xu, X., Zhang, Y., Ji, Z., … & Bao, F. (2022). Global seroprevalence and sociodemographic characteristics of Borrelia burgdorferi sensu lato in human populations: a systematic review and meta-analysis. BMJ Global Health, 7(6), e007744.
- Steinbrink, A., Brugger, K., Margos, G. et al. The evolving story of Borrelia burgdorferi sensu lato transmission in Europe. Parasitol Res 121, 781–803 (2022). https://doi.org/10.1007/s00436-022-07445-3
