Characterization of dominant cultivable lactobacilli and their antibiotic resistance profiles from faecal samples of weaning piglets

Abstract

Aims: To examine the lactic acid bacteria flora of weaning piglets, to define the distribution of different lactobacilli species in piglet faecal samples, and to determine the susceptibility phenotype to 11 antibiotic of different families. Methods and Results: The faecal samples were taken from piglets with good herd status at 11 and 28 days after weaning. The Lactobacillus isolates (n = 129) from 78 animals housed in pairs in 39 pens were preliminarily identified by their morphology and biochemical characteristics. Partial 16S ribosomal DNA (16S rDNA) was used to identify the isolates to the species level, and RAPD (randomly amplified polymorphism DNA) profiles to differentiate Lactobacillus isolates to the strain level. Based on these studies, 67 strains were selected for antibiotic resistant tests. The most numerous Lactobacillus species found in the piglets was Lactobacillus reuteri (n = 43). Other lactobacilli were L. salivarius (n = 15), L. agilis (n = 4), L. johnsonii (n = 2), L. vaginalis (n = 1), L. mucosae (n = 1) and L. gallinarum (n = 1). All the strains were susceptible to chloramphenicol, ampicillin and gentamicin. Two L. salivarius isolates and two L. reuteri isolates were found to be multiresistant. Conclusions: This study indicates that the faecal Lactobacillus flora in piglets consists mainly of L. reuteri, L. salivarius and L. acidophilus group lactobacilli, and the distribution of lactobacilli is similar between individuals of the same age and with the same diet. Most of the Lactobacillus isolates tested were sensitive to the antibiotics used in this study. Significance and Impact of the Study: Valuable information on Lactobacillus species distribution and their antibiotic resistance profiles in piglets is obtained.

Susceptibility of Bifidobacteria of Animal Origin to Selected Antimicrobial Agents

“…Hence, a variable but species-specific susceptibility was detected, nearly covering the whole concentration range tested (Figure 1(f)). Also a wide range of trimethoprim MICs with no clear breakpoint values was identified for certain Lactobacillus species [44]. This was led back to the presence of antagonistic components in the medium, complicating susceptibility testing concerning trimethoprim [11, 15].…”

Antimicrobial resistance of lactobacilli isolated from food

“…Although relatively rare in Gram-positive bacteria, the acquired trimethoprim resistance has been occasionally detected (Young et al 1987;Charpentier & Courvalin 1997). The data available (Korhonen et al 2007) indicate that within the species of lactobacilli, the range of the apparent trimethoprim resistance can be wide with no clear breakpoint values. Therefore, The results of trimethoprim susceptibility testing may be distorted by reading at 80% inhibition of the growth (broth microdilution method) and ignoring the slight growth within the inhibition zones (disk diffusion method).…”

Antibiotic Susceptibility of Probiotic Bacteria

“…The data available (Korhonen et al, 2007) indicate that within species of lactobacilli the range of apparent trimethoprim resistances can be wide with no clear breakpoint values. Therefore, the MIC testing of trimethoprim for LAB was not considered relevant.…”

“…One of the most investigated probiotic, L.rhamnosus GG, has been very effective in the treatment of viral diarrhea in children, most cases of which were caused by rotavirus. Other probiotic strains such as Lactocacillus casei Shirota, B. bifidum and S. thermophillus have also been shown to be effective in the treatment and prevention of rotavirus diarrhea in children (Korhonen, et al, 2007;Saavedra et al, 1994).…”