Emergence of extended-spectrum β-lactamases and AmpC-type β-lactamases in human Salmonella isolated in Spain from 2001 to 2005

• Published in: Journal of antimicrobial chemotherapy 2009-12, Vol.64 (6), p.1181-1186
• Main Authors: González-Sanz, Rubén, Herrera-León, Silvia, de la Fuente, Manuela, Arroyo, Margarita, Echeita, M. Aurora
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents - pharmacology; beta-Lactam Resistance; beta-Lactamases - biosynthesis; beta-Lactamases - genetics; Cephalosporins - pharmacology; Child; Child, Preschool; Conjugation, Genetic; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Electrophoresis, Gel, Pulsed-Field; Enterobacteriaceae; ESBLs; Escherichia coli - genetics; Female; Humans; Infant; Male; Microbial Sensitivity Tests; Middle Aged; molecular identification; Plasmids - analysis; Polymerase Chain Reaction - methods; resistance mechanisms; Salmonella - drug effects; Salmonella - enzymology; Salmonella - genetics; Salmonella - isolation & purification; Salmonella Infections - microbiology; Sequence Analysis, DNA; Spain; Young Adult
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkp361

Objectives To study the resistance to third-generation cephalosporins in Salmonella strains isolated from humans in a 5 year period in Spain, and to identify the responsible genes and their dissemination. Methods Twenty-seven isolates were analysed by PCR and sequencing to identify the genes responsible for the β-lactamase resistance phenotypes. The transferability of the phenotypes was tested by conjugation to Escherichia coli K12J53, plasmid detection with S1-PFGE, hybridization and PCRs of the transconjugants. The genetic relationship was determined by PFGE. Results We found blaCTX-M-9 and blaCTX-M-10 in Salmonella Virchow PT19. blaCTX-M-14 was detected in Salmonella (IV) 44:z4,z23:-, Salmonella Enteritidis PT6a, Salmonella Typhimurium DT193 and Salmonella Typhimurium DT104B. blaCTX-M-1 was found in Salmonella Litchfield. blaCTX-M-15 and blaCTX-M-32 were found in Salmonella Enteritidis PT1. blaSHV-12 was found in Salmonella Blockley, Salmonella Hadar PT2, Salmonella Enteritidis PT21, Salmonella Enteritidis PT1 and Salmonella Bredeney. blaSHV-2 was found in Salmonella Livingstone. blaCMY-2 was detected in Salmonella Bredeney, Salmonella Newport, Salmonella Enteritidis PT5b and Salmonella Heidelberg. blaDHA-1 was detected for the first time in Spain in Salmonella Newport. One strain of Salmonella Senftenberg harboured two extended-spectrum β-lactamases, blaSHV-12 and blaCTX-M-9. We have found a large variety of β-lactamase families as well as several members of major relevance, such as CTX-M-15, CTX-M-32, CMY-2 and DHA-1. XbaI-PFGE, conjugation assays and S1-PFGE hybridization showed that all these β-lactamases were mediated by plasmids. Conclusions This study demonstrates the emergence of a public health risk related to resistance to β-lactams in Salmonella. The resistance trends need to be monitored carefully.