Antimicrobial susceptibility of Salmonella strains isolated from retail meat products in Poland between 2008 and 2012

Abstract

A total of 106 Salmonella strains were isolated in the years 2008–2012 from retail meat products sampled in Poland. Strains from poultry meat (n = 81), pork (n = 7), beef (n = 3) and mixed meat (n = 15) were serotyped and subjected to antimicrobial susceptibility testing by the disk diffusion method (19 antibiotics). Twenty-one Salmonella serotypes were identified, with the three most common being Salmonella Enteritidis (34.9%), Salmonella Infantis (14.2%) and Salmonella Typhimurium (10.4%).The majority of the Salmonella strains (68.9%; n = 73) were resistant to one or more antimicrobial compound. Among the resistant isolates, 31 were resistant to one antibiotic, 4 to two, 10 to three, 13 to four, and 15 to five or more antibiotics.Of the Salmonella Enteritidis isolates, 54% were resistant to at least one antibiotic, while much higher frequencies of resistance were found in Salmonella Newport (100%), Salmonella Typhimurium (91%), Salmonella Hadar (85.7%), Salmonella Virchow (80%) and Salmonella Infantis (80%).The most common resistance observed among the Salmonella isolates was to nalidixic acid (52.8%). The isolates were also frequently resistant to tetracycline (32.1%), ampicillin (28.3%), streptomycin (28.3%) and sulphonamides (26.4%). All of the tested strains were susceptible to cefepime, cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, ertapenem and imipenem.Salmonella strains isolated from poultry meat showed the widest spectrum of resistance (to 12 of the 19 tested antimicrobials) compared with isolates from the other meat sources.The level of resistance among Salmonella strains isolated between 2008 and 2012 was consistently high: 59.1% in 2010, 84.6% in 2011 and 64.7% in 2012. In addition, there was an increase in the number of multiresistant strains over this period, from 23.1% in 2010 to 81.8% in 2012. The demonstration that meat products are a source of antibiotic resistant Salmonella strains is a serious concern for public health and food safety.