Pediatrics International (2016) 58, 1009–1013
doi: 10.1111/ped.12949
Original Article
Antimicrobial activity of lactobacillus strains against uropathogens Yoon Hee Shim, Seung Joo Lee and Jung Won Lee Department of Pediatrics, Ewha Women’s University School of Medicine, Seoul, South Korea Abstract
Background: The use of lactobacillus probiotics has been proposed as an alternative to prophylactic antibiotics for preventing urinary tract infection (UTI) in the era of antibiotic resistance. In this study, the antimicrobial activity of lactobacillus strains against uropathogens, was evaluated and compared with that of antibiotics. Methods: To evaluate inhibitory activities of lactobacilli against uropathogens, six lactobacillus strains (L. gasseri, L. rhamnosus, L. acidophilus, L. plantarum, L. paracasei, L. acidophilus) and four representative uropathogens of infantile UTI (extended-spectrum beta-lactamase [ESBL]( ) Escherichia coli, ESBL(+) E. coli, Proteus vulgaris, Enterococcus fecalis) were selected. Lactobacillus strain in vitro inhibition of each uropathogen was evaluated on MRS agar well diffusion assay and compared with that of commercial antibiotic discs. Results: Average inhibitory zone for each of the six lactobacillus strains against the four uropathogens showed slightly different but consistent inhibition (inhibitory zone diameter, 10.5–20.0 mm). This was different to that of the antibiotic discs, which had a wider range of inhibition (inhibitory zone diameter, 105 CFU/mL on suprapubically aspirated or catheterized urine) at Ewha Women’s University Mokdong Hospital, Korea. Eligible urine samples were cultured in TS soft agar (tryptic soy broth with 0.7% agar, BBL, Microbiology system, Cockeysville, MD, USA) at 37°C under aerobic conditions for 18–24 h and the uropathogens identified using VITEK 2 GramNegative card (bio-Merieux). The selected uropathogens were extended-spectrum-beta-lactamase (ESBL) ( ) Escherichia coli, ESBL (+) E. coli, Proteus vulgaris, and Enterococcus fecalis. A commercially available standard E. coli strain (ATCC 25922,
1010 YH Shim et al. Seattle, WA, USA) was also included to determine the optimal dosage for the study. Optimal dose
To select the optimal dose of lactobacillus strain, agar well diffusion assay was performed using L. gasseri HLAB 414 and standard E. coli (ATCC 25922). Aliquots (200 μL) of L. gasseri HLAB 414 supernatant at six different dosages (105, 106, 107, 108, 109 and 1010 CFU/mL) were placed in 6 mm MRS agar wells previously cut in TS soft agar plates seeded with standard E. coli 2 × 106 CFU/mL. After incubation at 37°C for 18–24 h, the lowest dosage with maximum inhibition was 109 CFU/mL, and was therefore identified as the optimal dose. Lactobacillus in vitro inhibition of uropathogens
To evaluate the lactobacillus in vitro inhibition of uropathogens, agar well diffusion assay was performed using six lactobacillus strains and four uropathogens. Aliquots (200 μL) of six lactobacilli suspensions (109 CFU/mL) were injected into 6 mm MRS agar wells previously cut in TS soft agar plates seeded with each uropathogen (2 × 106 CFU/mL). The final pH of suspension was examined and modified by adjusting to neutral pH 7.0. The plates were incubated at 37°C for 18–24 h. The diameter (mm) of the inhibitory zone around each well was measured. According to inhibitory zone diameter, antimicrobial activity was interpreted as weak (20 mm). No inhibition was defined as no clear zone around the well, with diameter
doi: 10.1111/ped.12949
Original Article
Antimicrobial activity of lactobacillus strains against uropathogens Yoon Hee Shim, Seung Joo Lee and Jung Won Lee Department of Pediatrics, Ewha Women’s University School of Medicine, Seoul, South Korea Abstract
Background: The use of lactobacillus probiotics has been proposed as an alternative to prophylactic antibiotics for preventing urinary tract infection (UTI) in the era of antibiotic resistance. In this study, the antimicrobial activity of lactobacillus strains against uropathogens, was evaluated and compared with that of antibiotics. Methods: To evaluate inhibitory activities of lactobacilli against uropathogens, six lactobacillus strains (L. gasseri, L. rhamnosus, L. acidophilus, L. plantarum, L. paracasei, L. acidophilus) and four representative uropathogens of infantile UTI (extended-spectrum beta-lactamase [ESBL]( ) Escherichia coli, ESBL(+) E. coli, Proteus vulgaris, Enterococcus fecalis) were selected. Lactobacillus strain in vitro inhibition of each uropathogen was evaluated on MRS agar well diffusion assay and compared with that of commercial antibiotic discs. Results: Average inhibitory zone for each of the six lactobacillus strains against the four uropathogens showed slightly different but consistent inhibition (inhibitory zone diameter, 10.5–20.0 mm). This was different to that of the antibiotic discs, which had a wider range of inhibition (inhibitory zone diameter, 105 CFU/mL on suprapubically aspirated or catheterized urine) at Ewha Women’s University Mokdong Hospital, Korea. Eligible urine samples were cultured in TS soft agar (tryptic soy broth with 0.7% agar, BBL, Microbiology system, Cockeysville, MD, USA) at 37°C under aerobic conditions for 18–24 h and the uropathogens identified using VITEK 2 GramNegative card (bio-Merieux). The selected uropathogens were extended-spectrum-beta-lactamase (ESBL) ( ) Escherichia coli, ESBL (+) E. coli, Proteus vulgaris, and Enterococcus fecalis. A commercially available standard E. coli strain (ATCC 25922,
1010 YH Shim et al. Seattle, WA, USA) was also included to determine the optimal dosage for the study. Optimal dose
To select the optimal dose of lactobacillus strain, agar well diffusion assay was performed using L. gasseri HLAB 414 and standard E. coli (ATCC 25922). Aliquots (200 μL) of L. gasseri HLAB 414 supernatant at six different dosages (105, 106, 107, 108, 109 and 1010 CFU/mL) were placed in 6 mm MRS agar wells previously cut in TS soft agar plates seeded with standard E. coli 2 × 106 CFU/mL. After incubation at 37°C for 18–24 h, the lowest dosage with maximum inhibition was 109 CFU/mL, and was therefore identified as the optimal dose. Lactobacillus in vitro inhibition of uropathogens
To evaluate the lactobacillus in vitro inhibition of uropathogens, agar well diffusion assay was performed using six lactobacillus strains and four uropathogens. Aliquots (200 μL) of six lactobacilli suspensions (109 CFU/mL) were injected into 6 mm MRS agar wells previously cut in TS soft agar plates seeded with each uropathogen (2 × 106 CFU/mL). The final pH of suspension was examined and modified by adjusting to neutral pH 7.0. The plates were incubated at 37°C for 18–24 h. The diameter (mm) of the inhibitory zone around each well was measured. According to inhibitory zone diameter, antimicrobial activity was interpreted as weak (20 mm). No inhibition was defined as no clear zone around the well, with diameter
