Survival of clinical and food acinetobacter spp. isolates to different stress conditions

Introduction: Acinetobacter spp. are commonly found in water and soil, but can also be found in contaminated areas, sewage, dumpsites, food and animals (Atrouni et al., 2016). The majority of the Acinetobacter species are isolated from meat and vegetables, but they can also be found in several types of foods such as fruits, cheese, milk, fish, shrimps, water and rice (Berlau et al., 1999; Carvalheira et al., 2017a; Carvalheira et al., 2017b). Members of the Acinetobacter baumannii group (A. baumannii, A. nosocomialis, A. pittii and A. seifertii) are major agents of nosocomial infections (Madigan et al., 2009). Other species non-A. baumannii, such as A. lwoffii, have been also sporadically involved in these infections (Turton et al., 2010). When introduced into the hospital environment, either by the food from the hospital’s kitchens or by the food, mainly fruits, that the visits offer to the patients (common practice in Portugal), contaminated foods could be a vehicle for the dissemination of these organisms into hospital settings. The aims of this study were to evaluate: i) if A. baumannii and A. lwoffii isolates, recovered from human and food samples, were susceptible to thermal processing method, such as exposure to 60 ºC, and to disinfection methods of vegetables and fruits, such as exposure to AMUKINA® and vinegar, and ii) the influence of food matrices on the behavior of isolates to these stress Conditions. Conclusions: Without food matrix Thermal stress was effective for the majority of isolates tested, except for food isolate 17.3 (Fig. 2; graph B1) which was able to resist until 60 minutes with logarithmic reductions of less than 0.5 log units. With exposure to vinegar, all isolates were sensitive and similar reductions were observed among clinical and food isolates (p>0.05). Treatment with AMUKINA® was also effective for all isolates, allowing reductions to values below the detection limit of the enumeration technique after 30 seconds for both clinical and food isolates. Comparing the survival after exposure to vinegar and AMUKINA®, despite both being effective, AMUKINA® was faster to eliminate Acinetobacter isolates. With food matrix Any food matrix conferred protection to the survival of the isolates when the different stress conditions were applied, with exception of only one food isolate that shown to be more resistant to the thermal stress in the presence of turkey meat matrix. Even though the small number of isolates tested in this study, exposure to 60 ºC, vinegar and AMUKINA® was effective on the elimination of the majority of Acinetobacter spp. isolates. Therefore, despite thermal processing is sufficient to eliminate Acinetobacter spp. present in meat, in order to avoid ready-to-eat food products to be a vehicle of transmission of these organisms, disinfection of vegetables and fruits should be done with vinegar or AMUKINA®.