Susceptibilities to Antimicrobials and Disinfectants in Salmonella Isolates Obtained from Poultry and Swine in Thailand

Abstract

ABSTRACT. Salmonella enterica isolates from poultry (n=125) and swine (n=132) in Thailand were investigated for antibiotic resistance, susceptibility to disinfectants (benzalkonium chloride (BKC), chlorhexidine digluconate (CHX), zinc chloride and copper sulfate) and cyclohexane tolerance. Forty-two percent were of multiple resistance to antibiotics. The minimum inhibitory concentrations (MICs) of all antibiotics against isolates from swine were higher than that against the isolates from poultry. There were generally few variations in MICs to all disinfectants, indicating that the isolates had either no or only a limited degree of developed resistance to the disinfectants tested. Only 5 isolates (1.9%) were tolerant to cyclohexane. The proton-dependent efflux systems did not play a major role in the reduced susceptibility to BKC and CHX, since susceptibility was not restored when an efflux inhibitor, carbonyl cyanide m-chlorophenylhydrazone (CCCP) was present. Successive exposure to subinhibitory concentrations of BKC and CHX generated mutants resistant to BKC and CHX. A spontaneous BKC-resistant derivative expressed cross-resistance to antibiotics, chloramphenicol and erythromycin. The mechanism responsible for cross-resistance between BKC and antibiotics was not driven by the proton motif force (PMF). KEY WORDS: benzalkonium chloride, multiple antibiotic resistance, Salmonella enterica, proton-dependent efflux system.

Control of Salmonella in food related environments by chemical disinfection

“…The MIC levels of tolerant strains were low (MICs 0.25-4 mg/l) and similar to findings by Randall, Cooles, Sayers, and Woodward (2001). No significant difference in the susceptibility to disinfectants (MICs, QAC included) of Salmonella isolates from poultry and swine in Thailand was reported (Chuanchuen, Pathanasophon, Khemtong, Wannaprasat, & Padungtod, 2008). The distribution of MICs of disinfectants was close to previous data (Aarestrup & Hasman, 2004).…”

Serotyping, RAPD Grouping and Antibiotic Susceptibility Testing of Salmonella Enterica Isolated from Retail Foods in Thailand

“…The frequent occurrence of S. Rissen in water and food products indicates that a foodborne or waterborne reservoir is a possible source (Bangtrakulnonth et al, 2004). S. Corvallis has been reported to grow in chicken and pig meats (Archambault et al, 2006;Vindigni et al, 2007;Chuanchuen et al, 2008), which this study corroborates, as S. Corvallis was a commonly recovered serovar from chicken meat samples (52%). Historically, S. Anatum has been a major cause of salmonellosis in Thailand: it is found in a variety of animal sources (Bangtrakulnonth et al, 2004) and was the most common Salmonella serotype isolated from both beef and pork (Vindigni et al, 2007).…”

Antimicrobial Resistance Genes in Salmonella enterica Isolates from Poultry and Swine in Thailand

“…In addition, having genes conferring resistance to multiple drugs was significantly associated with being multiresistance (p<0.01). Twenty-two percent of the Salmonella isolates were nega- aadA1 (6), aadA2 (6), aadB (6), bla TEM (6), cmlA (6), strA (2), strB (2), sul1 (3), sul2 (1), sul3 (6), tetA (6), tetB(2) AMP, CHP, SPC, STR, SUL, TET, TRI 11 (6.0) aadA1 (10), aadA2 (1), bla PSE-1 (5), bla TEM (9), cmlA (8), dfrA10 (1), dfrA12 (5), strA (9), strB (9), sul1 (6), sul2 (3), sul3 (9), tetA (8) tive to all the resistance genes tested, even through most of these isolates were resistant to at least one antimicrobial agent (data not shown).…”

“…A total of 184 Salmonella isolates previously isolated were studied [8,15]. They were originated from poultry (n=80) and swine (n=104) and comprised of 34 serotypes including 24 [2005][2006].…”