Retail Frozen Blended Beverages as Vehicles for Opportunistic Antibiotic-Resistant and Biofilm-Forming Bacteria

The consumption of milkshakes, slushies, and smoothies has increased due to their refreshing taste and nutritional benefits. However, the microbiological quality of these beverages poses significant public health concerns. This study is aimed at investigating the prevalence of pathogenic bacteria in these popular beverages, addressing a critical gap in food safety research. A total of 150 samples of milkshakes, smoothies, and slushies were collected, and the target bacteria were identified using microbiological and molecular methods. The obtained results revealed the prevalence of coliforms (50%), Klebsiella spp. (37.3%), Escherichia coli (9.3%), Acinetobacter spp. (4.6%), Listeria spp. (4.6%), and Staphylococcus spp. (4%) in the collected samples. Most isolates were sensitive to the tested antibiotics. Acinetobacter baumannii isolates exhibited high resistance levels against tetracycline (71.4%) and doxycycline (57.1%). The highest resistance among the 14 E. coli isolates was observed against ampicillin and sulfonamides (78.6%), while highest resistance rate among the Klebsiella isolates was observed against ampicillin (71.4%). Biofilm-forming ability varied among the isolates. Most Staphylococcus isolates (66.7%) and Acinetobacter isolates (71.4%) demonstrated strong biofilm-forming capacity, whereas the majority of Listeria isolates (85.7%) showed weak biofilm formation. These findings underscore the need for quality control measures to ensure continuous monitoring and enhancement of microbial safety of these products.