Download Induction of Ampicillin Resistance in E.coli and Salmonella species

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Induction of Ampicillin Resistance in E.coli and Salmonella
species by Sub-lethal Doses
Muhammad Salman Rasool*, Fraz Siddiqui**, Sheikh Ajaz Rasool***, Saleem Hafiz**
*D.J. Sindh Govt. Science, College Karachi, **Sindh Institute of Urology and Transplantation SIUT,
*** University of Karachi,
Abstract
Background: Antibiotic resistance is increasing steadily in pathogenic bacteria all over the world. The
induction of bacterial resistance by sub-lethal concentrations of ampicillin may be due to mutations and
adaptability to survive at sub-minimum inhibitory concentrations of ampicillin.
Objective: Demonstrate in-vitro model of acquisition of ampicillin resistance at sub-lethal concentrations.
Material and Methods: E.coli and Salmonella species were identified by conventional biochemical reactions,
API 20 E kits and by anti sera. Antibiotic disc diffusion tests and Minimum inhibitory concentrations were
performed according to CLSI (2012). 56 clinical isolates of E.coli and 47 strains of Salmonella species were
step wise exposed to sub-lethal concentrations of ampicillin.
Results: Out of 56 isolates of E.coli, 9 strains developed permanent resistance to ampicillin and 17 adapted to
intermediate resistant levels of ampicillin. Out of 47 isolates of Salmonella species, 8 strains developed
permanent resistance to ampicillin and 16 got adapted to intermediate resistance concentrations. Few strains
showed cross resistance to various antibiotics after exposure to ampicillin. Sub lethal concentrations of
ampicillin leads to the development of resistance which may have therapeutic implications.
Conclusion: Sub lethal concentrations of ampicillin should be avoided because exposure to these
concentrations may create the ability in bacteria to adapt higher concentrations of ampicillin and trigger the
bacteria to develop the resistance not only against ampicillin but also other groups of antibiotics.
Keywords: Antibiotic resistance, E.coli, Salmonella, Typhoid, Ampicillin, Sub lethal dosage
Post date: 2016-03-04 05:58:03
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Post modified date GMT: 2016-03-04 05:58:03
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