ANTIBIOTIC SUSCEPTIBILITY AND FREQUENCY OF RESISTANCE GENES PENA AND AMPC AMONG L.MONOCYTOGENES ISOLATES WITH CLINICAL, FOOD AND LIVESTOCK ORIGINS

Background and Aim:Since 1988 that Poyart & Salmeron were reported the first resistant Listeria monocytogenes (L.monocytogenes ) strain, increasing rates of resistance is reporting continuously all over the world. The aim of this study was the evaluation of resistance patterns in L.monocytogenes isolated from food, human, and livestock samples.Methods:In this research, 51 L.monocytogenes strains isolated from various specimens since 2009 to 2016 evaluated for antibiotic sensitivity pattern and minimum inhibitory concentration (MIC) of isolates to the following antibiotics (penicillin G, ampicillin, cotrimoxazole, Gentamicin and tetracycline ) was investigated using Agar Dilution Method . After DNA extraction from the isolates, PCR was done for evaluation of genetic basis of resistance to penicillinG and ampicillin.Results:According to MIC evaluation, 13 isolates of L.monocytogenes (25%) were resistant to ampicillin, 21 (40.38%) to penicillinG and 11 (21.15%) to Gentamicin . Resistance rate to tetracycline was 25%. The listeria isolates appeared susceptible to cotrimoxazole. PCR for amplification of resistance genes in β-lactam resistant isolates showed that 11(21.5%) and 5(9.61%) of strains contain penA and ampC genes respectively.Conclusion:In this study, relatively high level resistance to the first choice therapeutic drugs in treatment of listeriosis (penicillin and ampicillin) is important for clinicians. It is northworthy that cotrimoxazole as an alternative agent to penicillin (in allergic persons) has still good effect and all of L.monocytogenes are sensitive to it , however clinical isolates had higher levels of c resistance in comparison to the food and livestock ones.

کلیدواژه ها:

L.monocytogenes ، MIC ، penA ، ampC