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Antimicrobial effects of Lactobacillus plantarum and Lactobacillus acidophilus against multidrug-resistant enteroaggregative Escherichia coli

Kumar, Manesh, Dhaka, Pankaj, Vijay, Deepthi, Vergis, Jess, Mohan, Vysakh, Kumar, Ashok, Kurkure, Nitin V., Barbuddhe, Sukhadeo B., Malik, S.V.S., Rawool, Deepak B.
International journal of antimicrobial agents 2016 v.48 no.3 pp. 265-270
Escherichia coli, Lactobacillus acidophilus, Lactobacillus plantarum, anti-infective agents, antibacterial properties, coculture, colon, feces, histopathology, ileum, in vitro studies, in vivo studies, mice, multiple drug resistance, plate count, probiotics, quantitative polymerase chain reaction, therapeutics
The in vitro and in vivo antimicrobial effects of Lactobacillus plantarum and Lactobacillus acidophilus were evaluated individually and synergistically against multidrug-resistant enteroaggregative Escherichia coli (MDR-EAEC). In vitro evaluation of each probiotic strain when co-cultured with MDR-EAEC isolates revealed a reduction in MDR-EAEC counts (eosin–methylene blue agar) in a dose- and time-dependent manner: probiotics at a dose rate of 10¹⁰ CFU inhibited MDR-EAEC isolates at 72 h post-inoculation (PI), whereas at lower concentrations (10⁸ and 10⁹ CFU) MDR-EAEC isolates were inhibited at 96 h PI. The synergistic antimicrobial effect of both probiotic strains (each at 10¹⁰ CFU) was highly significant (P < 0.01) and inhibited the growth of MDR-EAEC isolates at 24 h PI. For in vivo evaluation, weaned mice were fed orally with 10⁷ CFU of MDR-EAEC. At Day 3 post-infection, treated mice were fed orally with the probiotic strains (each at 10¹⁰ CFU). Compared with the control, post-treatment a significant (P < 0.01) reduction in MDR-EAEC counts was observed in faeces by Day 2 and in intestinal tissues of treated mice by Days 3 and 4 as evidenced by plate count (mean 2.71 log and 2.27 log, respectively) and real-time PCR (mean 1.62 log and 1.57 log, respectively) methods. Histopathologically, comparatively mild changes were observed in the ileum and colon from Days 3 to 5 post-treatment with probiotics; however, from Day 6 the changes were regenerative or normal. These observations suggest that these probiotic strains can serve as alternative therapeutics against MDR-EAEC-associated infections in humans and animals.