Antimicrobial activity of cranberry juice (Vaccinium macrocarpon L.) ethanol extract against uropathogenic bacteria

Cranberry fruit (Vaccinium macrocarpon L) contains a mixture of phytochemicals such as flavonoids which consist of flavonoids, anthocyanins, proanthocyanidins, catechins, phenolic acids, and triterpenoids, all of which have possible antimicrobial (antibacterial, antifungal, and antiviral) activity.

This study aimed to determine the antibacterial effect of the ethanol extract of cranberry juice (CJ) against uropathogen commonly found in urinary tract infections (UTIs) associated with pregnancy.

Cranberry fruits were purchased from local markets and juiced, filtered, and dried. The dried powder was extracted with 70% ethanol for 8-10 days. The bacterial isolates used in this study [Escherichia coli, Proteus vulgaris, Staphylococcus aureus, Enterococcus sp., and coagulase-negative Staphylococci (CNS)] were collected from the Maternity and Children Hospital in Al-Diwaniyah City, Iraq. The antibacterial activity of the ethanol extract of CJ was measured using a standard Disc diffusion method. Sterile paper discs were soaked in 20 µl of different concentrations (12.5, 25, 50, and 100 mg/ml) of the extract, placed in Mueller-Hinton agar plates, and inoculated with bacterial cultures adjusted to 0.5 McFarland standards. Amoxicillin (30 µg) was used as a positive control, and 70% ethanol was used as a negative control.

The ethanol solution of CJ displayed a significant (p < 0.05) inhibitory activity against all tested bacteria. The CNS showed the highest sensitivity with 100% inhibition, followed by S. aureus (90%), Enterococcus sp. (85%), P. vulgaris (75%), and E. coli (60%). The effect was dose dependent, as increasing the extract concentration resulted in broader inhibition zones.

The results show that the ethanol extract of CJ has potent antibacterial activity against uropathogenic bacteria, suggesting a possible role for CJ ethanol extract in treating UTIs when combined with recently emerging facts about increasing antibiotic resistance.