Antibiotics are one of the greatest scientific achievements of modern medicine, but excessive use is creating challenges for the future of medicine. Antibiotic resistance (AR) is thought to cause changes in bowel habits and an increased risk of gastroenteritis, but it may also increase the risk of overweight, obesity, autoimmune and atopic diseases, and a low response to vaccines and cancer, likely mediated by antibiotic-induced gut dysbiosis. Probiotic add-on therapy could partially prevent antibiotic-induced gut dysbiosis, but their antibiotic sensitivity features likely limits this potential. The EFSA (European Food Safety Authority) guidelines consider the use of probiotics whose antibiotic-resistant profile could be transferable an important hazard. Recently, a strain of B. breve (PRL2020) has shown to be resistant to amoxicillin and amoxicillin-clavulanate (AC) by applying the microdilution protocol according EFSA guidelines. After verifying that horizontal gene transfer is unlikely to take place, this feature suggests its concomitant use with these specific antibiotics. The results of our tests demonstrated that the strain PRL2020 is indeed endowed with amoxicillin- and AC-resistant properties and that it is also insensitive to ampicillin. In-depth analysis of the annotated genome sequence of B. breve PRL2020 was employed to query the Comprehensive Antibiotic Resistance Database (CARD) using Resistance Gene Identifier (RGI) software (version 5.2.1). The similarity among the AR determinants found was studied through nucleotide sequence alignment, and it was possible to verify not only the absence of genes explaining these features in the flanking regions but also the presence of genetic sequences (rpoB and erm(X)) putatively responsible for rifampicin and erythromycin resistance. Both features are not phenotypically expressed, and for these antibiotics, the strain is within the EFSA limits. Analysis of the flanking regions of these genes revealed possible mobile elements upstream and downstream only in the case of the erm(X) gene, but the features of the Insertion Sequences (IS) are described as not to cause horizontal transfer. Our findings on strain PRL2020 demonstrate that its AR profile is compatible with antibiotics when taken with the aim of reducing the risk of dysbiosis.

Bacteriophages are responsible for significant material and time losses in the dairy industry. This because these viruses infect the selected lactic starter cultures used for milk fermentation, i.e., the first stage toward cheese production. Standard detection techniques are time- and labor-consuming, causing huge costs related to production plant sanitation and product wasting. A new type of biosensor for early detection of bacteriophage contamination is highly demanded by the milk processing market, and inkjet-printed electrochemical sensors could be the answer. Inkjet printing is a well-known technology that has been revisited in recent years, using silver nanoparticle (AgNP) based inks for low-cost and easy fabrication of sensing and biosensing systems on flexible and eco-compatible substrates. In this research, we studied inkjet printing for the manufacturing of both interdigitated electrodes arrays (IDEAs), and a versatile system to monitor bacterial cultures by electrochemical impedance spectroscopy (EIS). In particular, we studied this biosensing system for the detection of bacteriophages by comparing its performance with standard microbiological methods. We performed electrical and morphological characterizations of the devices produced with a consumer-use inkjet printer with commercial AgNPs ink on flexible substrates, such as office paper, polyethylene (PET), and photo paper. We used light microscopy optical analysis, profilometry, atomic force microscopy (AFM), and scanning electron microscopy (SEM) imaging to define the objects resolution, their real dimensions, and thickness. We also investigated the devices’ conductivity and layout, by EIS measurements with a standard buffer solution, i.e., phosphate buffered saline (PBS). Finally, we tested our system by monitoring Lactococcus lactis cultures and bacteriophage infection. We compared the results to those obtained by two standard microbiological methods in terms of response time, proving that our technique requires less than half the time of other methods and no specialized personnel.