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Studies on erythromycin resistance in lactic acid bacteria from fermented food.

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Relation http://ir.cftri.com/11765/
 
Title Studies on erythromycin resistance in lactic
acid bacteria from fermented food.
 
Creator Surya Chandra Rao, Thumu
 
Subject 11 Antibiotics Chemistry
02 Fermented foods
 
Description There is a great deal of concern towards the use of antibiotics in food animals and
birds, around the world. This is known to contribute in the development and
spread of antibiotic resistant organisms. Evidences are now mounting that
antibiotic resistance in pathogens being detected is due to non human antibiotic
use. In line with human pathogens, now-a-days increased attention is being driven
towards the safety of bacteria applied in food. Among food microorganisms, lactic
acid bacteria (LAB) are natural and profitable inhabitants of diverse environments
including vegetables, soil, gastrointestinal tract etc. Although antibiotic resistance
in LAB is not detrimental to well being of humans and animals, there is, however,
a concern that they might participate in the transfer of resistance to human
pathogens.
Although antibiotic resistance in LAB has been reported from several
developed countries, data from developing countries such as India is either
negligible or absent. In this context, the present research was undertaken to
investigate the prevalence of antibiotic resistance in particular, erythromycin
resistance (ERr) in LAB from diverse food sources. In addition, ERr is also
accompanied with tetracycline resistance (TCr) as they are often found co-existing.
To achieve this, selective screening with erythromycin was carried out and a total
of 60 LAB cultures encompassing species of Enterococcus, Lactobacillus,
Pediococcus and Leuconostoc were isolated from idli batter, dairy products (milk,
curd Khoa, buttermilk) and chicken sausages.
With a diversified phenotypes of ERr, the LAB isolates harbored resistance
genes such as erm(B), msr(C), tet(M), tet(L), tet(K), tet(W) and lnu(B) on either
plasmids or chromosome. Among the several LAB, erm(B) gene was found
associated with tet(W), tet(L), tet(M), lnu(B) and msr(C) on single plasmids of
Enterococcus or Lactobacillus species. Phenotypic induction studies with
macrolides suggested diverse MIC values with macrolides, lincosamides and
streptogramin B (MLSB) antibiotics. These observations revealed the importance
of performing phenotypic tests before the use MLS antibiotics in combination for
possible treatment of enterococcal infections. Genetic expression studies showed
the induction of tet(W) gene in presence of high concentrations of the antibiotic
(tetracycline) substantiating the survival of these bacteria in antibiotics challenged
environments.
Subsequently, in vitro conjugation studies were carried out with selected
LAB isolates and the indicated the plasmid mediated transfer of ERr and TCr gene
to Enterococcus faecalis JH2-2 strain. The findings of the overall investigation
revealed the prevalence of antibiotic resistant LAB in diverse fermented foods.
The presence of several erythromycin and tetracycline resistance genes and the
ability to transfer these genes to pathogens indicated the potentiality of LAB in
disseminating antibiotic resistance through food chain. Thus, bacterial isolates
such as LAB intended for use as starter cultures or probiotics need to be evaluated
for transferable antibiotic resistance genes to curb its (antibiotic resistance) spread.
 
Contributor Prakash, M. Halami
 
Date 2014
 
Type Thesis
NonPeerReviewed
 
Format application/pdf
 
Language en
 
Rights —
 
Identifier http://ir.cftri.com/11765/1/surya%20thesis.pdf
Surya Chandra Rao, Thumu (2014) Studies on erythromycin resistance in lactic acid bacteria from fermented food. PhD thesis, University of Mysore.