Activity of antimicrobial drugs against bacterial pathogens under mild hypothermic conditions

Infections are a common problem in cardiac arrest survivors. Antimicrobial drugs are often administered in routine care during treatment of patients with mild therapeutic hypothermia (MTH). Because there is to date no evidence for the pharmacodynamics of antimicrobial drugs under MTH conditions, we investigated the in vitro activity of common antimicrobials against clinically relevant bacterial pathogens.

Activities of antimicrobial drugs against clinically relevant bacterial pathogens were assessed in vitro by disk diffusion and broth microdilution assays at normothermic (37°C) and hypothermic (32°C) conditions.

Seventy-three bacterial isolates were tested in disk diffusion and 15 in broth microdilution assays. Mean differences in zone diameters and minimal inhibitory concentration ratios were 0.6 mm (95% confidence interval, 0.3-0.9 mm) and 0.98 (95% confidence interval, 0.95-1.02), respectively, meeting predefined criteria for equivalence of in vitro antimicrobial activity.

The presented data provide reassuring evidence that the intrinsic activity of antimicrobials seems to be unaltered in MTH. However, further studies evaluating the pharmacokinetics including target site concentrations of the respective drugs and in vivo pharmacodynamics are necessary to complement our understanding of the appropriate use of antimicrobials in MTH.