Objectives: Antimicrobial susceptibility testing of Lactobacillus spp. used in probiotics products is advisable for checking biosafety. In fact probiotics should not carry acquired resistance potentially transferable to endogenous bacteria; moreover, intrinsic resistance could prevent treatment of a infection due to Lactobacillus spp. However there is still a lack of agreement on the guidelines of the susceptibility testing of Lactobacillus spp. and of the interpretative breakpoints. The aim of this study was to test the susceptibility of Lactobacillus sp.using the guidelines of the new 2006 CLSI M45-A document for infrequently isolated or fastidious bacteria. Methods: We tested the susceptibility to ampicillin, meropenem, vancomycin, gentamycin, erythromycin, clindamycin (recommended by CLSI, 2006) and, also, 2 cephaloporins and 2 fluoroquinolones of 19 Lactobacillus isolates from 5 fermented foods, 5 food supplements and 4 vaginal products available in Italy. The strains were isolated using different media under standardised cultivation conditions. The species designation was determined by standardised methods including API kits and PCR. MICs were obtained by broth microdilution according to 2006 CLSI document. Results: The MIC results were evaluated using CLSI breakpoints to predict clinical success and microbiological breakpoints suggested by FEEDAP Committee (EFSA J., 2006) to distinguish probiotic strains with acquired resistance. All the Lactobacillus isolates were β-lactamase negative and susceptible to ampicillin and imipenem by both breakpoints. The isolates of L. plantarum, L. salivarius and L. paracasei confirmed intrinsic-resistance to vancomycin; the other isolates tested had MIC ≤ 4 mg/L (susceptibility breakpoint). Gentamycin had poor activity against Lactobacillus isolates. Atypical resistance to erythromycin occurred in 1 L. salivarius isolate. A wide range of MICs was observed for cephalosporins and fluoroquinolones. Conclusion: The results showed that Lactobacillus isolates used in probiotics do not show particular risk of acquired and potentially transferable resistance. However, for Lactobacillus isolates involved in serious infections, the marginal susceptibility or resistance to some relevant drugs should be taken into account.
Antimicrobial susceptibility of Lactobacillus species used in probiotic products
BLANDINO, Giovanna;NICOLOSI, DARIA;
2008-01-01
Abstract
Objectives: Antimicrobial susceptibility testing of Lactobacillus spp. used in probiotics products is advisable for checking biosafety. In fact probiotics should not carry acquired resistance potentially transferable to endogenous bacteria; moreover, intrinsic resistance could prevent treatment of a infection due to Lactobacillus spp. However there is still a lack of agreement on the guidelines of the susceptibility testing of Lactobacillus spp. and of the interpretative breakpoints. The aim of this study was to test the susceptibility of Lactobacillus sp.using the guidelines of the new 2006 CLSI M45-A document for infrequently isolated or fastidious bacteria. Methods: We tested the susceptibility to ampicillin, meropenem, vancomycin, gentamycin, erythromycin, clindamycin (recommended by CLSI, 2006) and, also, 2 cephaloporins and 2 fluoroquinolones of 19 Lactobacillus isolates from 5 fermented foods, 5 food supplements and 4 vaginal products available in Italy. The strains were isolated using different media under standardised cultivation conditions. The species designation was determined by standardised methods including API kits and PCR. MICs were obtained by broth microdilution according to 2006 CLSI document. Results: The MIC results were evaluated using CLSI breakpoints to predict clinical success and microbiological breakpoints suggested by FEEDAP Committee (EFSA J., 2006) to distinguish probiotic strains with acquired resistance. All the Lactobacillus isolates were β-lactamase negative and susceptible to ampicillin and imipenem by both breakpoints. The isolates of L. plantarum, L. salivarius and L. paracasei confirmed intrinsic-resistance to vancomycin; the other isolates tested had MIC ≤ 4 mg/L (susceptibility breakpoint). Gentamycin had poor activity against Lactobacillus isolates. Atypical resistance to erythromycin occurred in 1 L. salivarius isolate. A wide range of MICs was observed for cephalosporins and fluoroquinolones. Conclusion: The results showed that Lactobacillus isolates used in probiotics do not show particular risk of acquired and potentially transferable resistance. However, for Lactobacillus isolates involved in serious infections, the marginal susceptibility or resistance to some relevant drugs should be taken into account.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
