AUTHOR=Chuma Takehisa , Miyasako Daisuke , Hesham Dahshan , Takayama Tomoko , Nakamoto Yuko , Shahada Francis , Akiba Masato , Okamoto Karoku 

TITLE=Chronological Change of Resistance to β-Lactams in Salmonella enterica serovar Infantis Isolated from Broilers in Japan

JOURNAL=Frontiers in Microbiology

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2013.00113

DOI=10.3389/fmicb.2013.00113

ISSN=1664-302X

ABSTRACT=<p>Epidemiologic surveillance study was conducted in southern Japan to determine the antimicrobial resistance phenotypes and characterize the β-lactamase genes and the plasmids harboring these genes in <italic>Salmonella enterica</italic> serovar Infantis (<italic>S</italic>. Infantis) isolates from broilers. Between January, 2007 and December, 2008, a total of 1,472 fecal samples were collected and examined at the Laboratory of Veterinary Public Health, Kagoshima University, Japan. In 93 (6.3%) isolates recovered, 33 (35.5%) isolates showed resistance to cefotaxime, an extended-spectrum cephalosporin (ESC), conferred by TEM-20, TEM-52 and CTX-M-25 extended-spectrum β-lactamases (ESBLs). In addition to ESC-resistance, eight (8.6%) isolates exhibited resistance to cefoxitin mediated by CMY-2 AmpC β-lactamase. Plasmid analysis and polymerase chain reaction replicon typing revealed the <italic>bla</italic><sub>TEM-20</sub> and <italic>bla</italic><sub>CMY-2</sub> genes were associated with IncP plasmids, <italic>bla</italic><sub>TEM-52</sub> was linked with a non-typable plasmid and <italic>bla</italic><sub>CTX-M-25</sub> was carried by an IncA/C plasmid. Non-β-lactam resistance to streptomycin, sulfamethoxazole, and oxytetracycline encoded by the <italic>aadA1</italic>, <italic>sul1</italic>, and <italic>tet</italic>(A) genes, respectively, was found in 86 (92.5%) isolates. Resistance to kanamycin and ofloxacin was exhibited in 12 (12.9%) and 11 (11.8%) isolates, respectively, the former was mediated by <italic>aphA1-Iab</italic>. These data indicate that <italic>S.</italic> Infantis isolates producing ESBLs and AmpC β-lactamase have spread among broiler farms in Japan. These data demonstrated that the incidence of ESC-resistant S. Infantis carrying <italic>bla</italic><sub>TEM-52</sub> remarkably increased and <italic>S.</italic> Infantis strains harboring <italic>bla</italic><sub>CMY-2</sub>, <italic>bla</italic><sub>TEM-20</sub>, or<italic> bla</italic><sub>CTX-M-25</sub> genes emerged from broilers in Japan for the first time in 2007 and 2008.</p>