Biogenic amines (BA) are simple organic bases of low molecular weight, formed during decarboxylation of amino acids. Ripened cheeses provide suitable conditions for the development of bacteria and production of BAs. The aim of the present study was to investigate the presence of eight BAs in ripened cheese samples (n = 125) using a high-performance liquid chromatography with diode array detector (HPLC-DAD). Furthermore, microbiological analyses towards identification of bacteria using matrix-assisted laser desorption ionisation—time of flight mass spectrometry (MALDI-TOF MS) were performed. Cadaverine and putrescine were detected in 28.0% and 20.8% of cheese samples at concentrations ranging from 6.12 to 2871 mg/kg and 5.74 to 441 mg/kg, respectively. High amounts of putrescine and cadaverine in cheeses were associated with the presence of Hafnia alvei. Tyramine was identified in 28.0% of samples in the concentration range of 5.62–646 mg/kg. High concentrations of this amine was found in cheeses containing Enterococcus faecium and Enterococcus faecalis. Histamine content, the only BA restricted in food according to Regulation 2073/2005, was observed above 100 mg/kg in 11.2% of the cheeses. Ripened cheeses available on the local retail market may contain significant levels of biogenic amines and may pose a potential health hazard to consumers.

Introduction: The prevalence of potentially pathogenic microorganisms in different foods is widely researched. The aim of this study was to investigate the prevalence and antimicrobial resistance of selected Enterobacterales species isolated from retail food of animal origin in Poland. Material and Methods: Cold cuts, cold-smoked fish and cheeses making 194 samples were tested with the ISO horizontal method for the detection of Enterobacteriaceae , and then Enterobacterales isolates were identified using matrix-assisted laser desorption/ionisation–time of flight mass spectrometry (MALDI-TOF). The isolates’ antimicrobial susceptibility was determined using the minimal inhibitory concentration method. Results: Enterobacterales were detected in 159 (82.0%) samples, from which 226 bacterial isolates were recovered. Six bacterial species accounted for 65.9% of Enterobacterales isolates: Escherichia coli (n = 41), Enterobacter cloacae (n = 26), Hafnia alvei (n = 25), Citrobacter spp. (n = 20), Serratia liquefaciens (n = 20) and Klebsiella oxytoca (n = 17). The isolated E. coli strains showed low resistance to seven antimicrobials. E. cloacae isolates were mostly resistant to ampicillin (76.9%) and azithromycin (38.5%), S. liquefaciens to colistin (100%) and H. alvei strains to colistin (96.0%) and ampicillin (60.0%). The majority of K. oxytoca isolates (70.6%) were resistant to ampicillin, whereas only five Citrobacter isolates were. Twenty of the total pool of isolates (8.8%) were defined as multidrug resistant. Conclusion: Retail food of animal origin can be contaminated with various species of Enterobacterales, including microorganisms pathogenic to humans as well as others resistant to commonly used antimicrobials.