| Title |
Macrolide Resistance and In Vitro Selection of Resistance to Antibiotics in Lactobacillus Isolates |
| Author |
Lorenzo Drago1,2*, Roberto Mattina3, Lucia Nicola1, Valentina Rodighiero2, and Elena De Vecchi1 |
| Address |
1Lab of Clinical-Chemistry and Microbiology, IRCCS Galeazzi Institute, Via R. Galeazzi 4, 20161 Milan, Italy, 2Lab of Clinical Microbiology, Department of Clinical Science L.Sacco, University of Milan, Via GB Grassi 74, 20157 Milan, Italy, 3Department of Public Health, Microbiology and Virology, University of Milan, Via Pascal 36, 20133 Milan, Italy |
| Bibliography |
Journal of Microbiology, 49(4),651-656, 2011,
|
| DOI |
|
| Key Words |
lactobacilli, antibiotics, selection of resistance |
| Abstract |
Spreading of resistance to antibiotics is of great concern due to the increasing rate of isolation of multiresistant
pathogens. Since commensal bacteria may transfer determinants of resistance to pathogens, studies on development
of resistance should include also lactobacilli. Resistance to macrolides, penicillins and tetracycline
was determined in 40 isolates of Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus crispatus,
and Lactobacillus casei isolated from faeces of apparently healthy volunteers. Frequency of mutation and
changes in susceptibility after serial exposure to these antibiotics at concentrations of 4× and 8× MIC were
evaluated in susceptible isolates. Acquired resistance was defined as an increment in MIC values of at least
four times in respect to the pre-selection values. Resistance to macrolides and/or tetracycline was identified
in 14 and 4 isolates, respectively. ermB gene and A2058G mutation in 23S rRNA were detected in macrolide
resistant isolates. Frequencies of mutation of susceptible isolates (n=26) were lower for ampicillin and erythromycin
than for tetracycline. Serial exposure to antibiotics led to selection of resistant mutants. However,
acquired resistance was rather unstable and was lost after subcultures in antibiotic-free medium in most
mutants. Resistance to erythromycin was associated to a A2058G mutation in 23S rRNA. In conclusion,
results indicate that resistance to macrolides and tetracycline is present among intestinal lactobacilli. Decrease
in susceptibility following serial exposure to antibiotics might occur in lactobacilli, in a strain- and antibiotic-
dependent way. Since lactobacilli are often used as probiotics, their ability to acquire resistance should
be evaluated for isolates candidate to be included in probiotics based products. |
