Determination of Antimicrobial Susceptibility of Listeria Monocytogenes from Food by E-Test

U radu je istražena osjetljivost na antimikrobne tvari bakterije Listeria monocytogenes (n=26) izoliranih iz hrane i proizvodnih pogona primjenom E-testa. Određene su MIC vrijednosti ampicilina, gentamicina, vankomicina, streptomicina, linezolida, azitromicina, rimfapicina, oksacilina, trimetoprim/sulfametoksazola i ciprofloksacina. Svi su izolati bili osjetljivi na klinički relevantne antimikrobne lijekove gentamicin, streptomicin, azitromicin, rifampicin, trimetoprim/sulfametoksazol i ciprofloksacin. Distribucija izolata L. monocytogenes prema MIC vrijednostima bila je za većinu tvari u nižem rasponu u odnosu na EUCAST podatke. Pet izolata (19,23 %) L. monocytogenes bilo je otporno na najmanje jednu tvar, a svi su izolirani s radnih površina, sirovine i opreme u mesnoj industriji. Dva su izolata bila otporna na vankomicin, po tri na linezolid i oksacilin, a jedan na sve tri tvari. Jedan izolat je pokazao otpornost na vankomicin, linezolid i ampicilin. Također, u otpornih izolata izmjerene su i visoke MIC vrijednosti za azitromicin-rifampicin, ampicilin-oksacilin, odnosno streptomicin-linezolid. Rezultati ukazuju na nisku razinu otpornosti L. monocytogenes iz hrane na klinički relevantne antimikrobne lijekove. S druge strane nalaz višestruko otpornih L. monocytogenes na radnim površinama i opremi u mesnoj industriji upućuje na rizik prijenosa antimikrobne rezistencije kroz lanac proizvodnje hrane.In this study the antimicrobial susceptibility of Listeria monocytogenes from food and food processing facilities (n=26) was tested by E-test. Minimal inhibitory concentrations of ampicillin, gentamicin, vancomycin, streptomycin, linezolid, azitromycin, rifampicin, oxacillin, trimethoprim/sulphametoxazol and ciprofloxacin were measured. All isolates were susceptible to clinically relevant antibiotics gentamicin, streptomicin, azitromycin, rifampicin, trimethoprim/sulphametoxazol and ciprofloxacin. Distribution of L. monocytogenes according to MIC levels ranged for most agents in lower values compared to EUCAST data. Five isolates (19.23 %) of L. monocytogenes was resistant at least to one antimicrobial agents, and all originated from raw material, food contact surfaces and equipment in meat processing plant. Two isolates were resistant to vancomycin, three to linezolid and oxacillin, and one to all three agents. One isolate showed the resistance to vancomycin, linezolid and ampicillin. Also, in the case of resistant isolates, the high-level MIC of azitromycin-rifampicin, ampicillin-oxacillin and streptomicinlinezolid were recorded. Results show the low level of resistance toward clinically relevant antimicrobials in L. monocytogenes from food. Contrary, the occurrence of multi-resistant L. monocytogenes strains in meat-processing facility samples indicates the risk of antimicrobial resistance transfer along the food producing chain