Isolation and Identification of Staphylococcus aureus in Fresh Juice Samples from Juice Shops in Tehran, Iran

Background: Staphylococcus aureus is a major foodborne pathogen responsible for staphylococcal food poisoning (SFP) worldwide. Fresh fruit juices, which are increasingly consumed for their health benefits, are often prepared on-site without any heat treatment, making them susceptible to microbial contamination. In Tehran, Iran, fresh juices are widely sold in juice shops; however, limited data exist regarding the prevalence of S. aureus in these products. Objectives: This study aimed to isolate and identify S. aureus in fresh juice samples collected from juice shops across Tehran, Iran, using standard microbiological methods. Methods: A total of ۳۰ fresh juice samples were randomly collected from various juice shops in different districts of Tehran over a one-month period (April to May ۲۰۲۶). All samples were transported to the laboratory under cold chain conditions (۴°C) within ۲ hours. The samples were enriched in Giolitti-Cantoni (GC) broth at ۳۷°C for ۲۴-۴۸ hours, followed by subculture onto Baird-Parker Agar (BPA) and Mannitol Salt Agar (MSA). Presumptive S. aureus colonies were identified based on morphological characteristics (Gram-positive cocci in grape-like clusters) and confirmatory biochemical tests, including catalase, oxidase, and coagulase tests. Results: Out of ۳۰ fresh juice samples, ۱۳ samples (۴۳%) showed preliminary positive results in GC broth. After selective culture on BPA and MSA, ۸ samples (۲۶.۷%) exhibited characteristic colonies of S. aureus. All ۸ isolates were Gram-positive cocci with grape-like clusters, catalase-positive, and oxidase-negative. The coagulase test confirmed that ۶ out of ۸ isolates (۷۵%) were coagulase-positive, identified as Staphylococcus aureus. The remaining ۲ isolates (۲۵%) were coagulase-negative staphylococci (CONS). The overall prevalence of S. aureus in fresh juice samples was ۲۰% (۶ out of ۳۰ samples). Conclusion: The presence of S. aureus in ۲۰% of fresh juice samples from Tehran juice shops indicates a significant level of contamination, posing a potential public health risk. This finding highlights the urgent need for improved hygiene practices, regular sanitization of equipment, proper handwashing by food handlers, and routine microbiological monitoring of juice shops in Tehran. Further studies using molecular methods (e.g., PCR for enterotoxin genes) and antibiotic susceptibility testing are recommended to fully characterize the isolated strains and assess the associated health risks.

کلیدواژه ها:

Staphylococcus aureus ، fresh juice ، food contamination ، Tehran ، coagulase test ، food safety ، juice shops