engleski

Gram-negative bacteria as medicinal herbs contaminants and their antimicrobial resistance

Medicinal herbs which are widely used in health care can be contaminated with microbes and insects (1). EuPharm set the limits for total microbial count (aerobic microbes max. 5 x 105 and fungi max 5 x 103 CFU/g), E. coli (absence or max 103 CFU/g), bile tolerant gram-negative bacteria (102- 104 CFU/g), while Salmonella spp. should be absent in 25 g. Since contamination of medicinal herbs with bacteria resistant to antimicrobials poses a health risk, this study aimed to assess contamination with gram-negative bacteria in roots and seeds/fruits (N=91) of 17 medicinal herbs. Gram-negative bacterial strains were identified using Api® 20E/NE tests, while susceptibility testing to antimicrobials was performed using disk diffusion assay according to CLSI recommendations. Results showed that 25% of root and 17% of seed/fruit samples were contaminated with gram- negative bacteria at concentration up to 104 CFU/g, while 8.5% of seed/fruit samples contained 105 CFU/g. Aeromonas hydrophila dominated in roots and seeds/fruits (75% and 68%, respectively), followed by Klebsiella spp., Serratia spp., Enterobacter spp. and Pseudomonas spp. E. coli was present in 3% of samples under tolerable concentration, while Salmonella spp. was not detected. Klebsiella spp. strains showed high resistance to penicillin G, amoxicillin and low resistance to ampicilin/sulbactam, gentamicin, amikacin and fluoroquinolones as well as low to moderate resistance to cephalosporins. Enterobacter spp. strains were highly resistant to penicillin and amoxicillin, moderately resistant to ampicilin/sulbactam, cefuroxim and cefoxitin, while low number of strains was resistant to ceftriaxone, and none to gentamicin, amikacin and fluoroquinolones. P. aeruginosa strains were highly resistant to -lactams. These data suggests that medicinal herbs are source of antibiotic resistant bacteria, and special care must be taken when handling with this source of contamination especially in units with immunocompromised patients. 1. Kosalec et al. Arh Hig Rada Toksikol, 2009 ; 60: 485-501.

Medicinal herbs; E. coli; Gram-negative bacteria; antibiotics

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