Chlorhexidine Gluconate Tolerance by Acinetobacter spp. Isolated from Foods Originated from Brazil

In recent years, Acinetobacter spp. have emerged as opportunistic food-borne pathogens worldwide. The purpose of this study was to evaluate the tolerance to chlorhexidine by Acinetobacter spp. isolated from foods that are handled and consumed without any prior heat treatment.

Eleven Acinetobacter spp. isolates from ready-to-eat salads and four from raw goat milk were previously collected. The samples were evaluated for tolerance to Chlorhexidine Gluconate (CG) based on the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC). The evaluation was performed using the dilution method in titration microplates. Statistical analysis by GraphPad software was performed using the t-test to compare the values.

The MIC and MBC of CG varied according to the origin of the isolates. Goat milk Acinetobacter spp. isolates were inhibited at MIC and MBC of £7.8 ppm CG. For most Acinetobacter spp. isolated from salads, however, MIC and MBC values ranged between 31.2-62.5 ppm, which are values generally correlated with clinical isolates. An MIC of 250 ppm was verified for only one isolate (F2R21).

Even food isolates can present MIC and MBC values for CG comparable to those of multidrug resistant isolates from clinical origin, suggesting that this sanitizer should be used sparingly for food handlers.