Emergence of blaCTX-M-15, blaTEM-169 and blaPER-1 extended-spectrum β-lactamase genes among different Salmonella enterica serovars from human faecal samples. Issue 7 (2nd July 2016)

• Record Type: Journal Article
• Authors: Tajbakhsh, Mercedeh; Avini, Mohammad Yaghoobi; Alikhajeh, Jahan; Tajeddin, Elahe; Rahbar, Mohammad; Eslami, Parisa; Alebouyeh, Masoud; Zali, Mohammad Reza
• Is Part Of: Infectious diseases. Volume 48:Issue 7(2016:Jul.)
• Page Start: 550
• Page End: 556
• Publication Date: 2016-07-02
• Subjects: Antimicrobial resistance -- non-typhoidal Salmonella -- β-lactamase activity; Communicable diseases -- Periodicals; Communicable Diseases -- Periodicals; Communicable diseases; Periodicals; 616.9
• DOI: 10.3109/23744235.2016.1166260
• Languages: English
• ISSNs: 2374-4235

Abstract

Abstract: Background: Broad-spectrum β -lactams are used for empirical therapy of severe infections with non-typhoid Salmonella serotypes; however, activities of these drugs against the strains producing different β -lactamase is not so clear. This study investigated the prevalence of β -lactamase genes among isolates of S. enterica serovars from human faecal samples and determined their diversity in activity against different β -lactams. Methods: Antimicrobial resistance of faecal isolates of S. enterica to extended-spectrum cephalosporins was analysed and MIC values were determined for the strains presenting extended-spectrum β -lactamases (ESBLs) phenotypes. The β -lactamase genes were identified by PCR and sequencing. β -lactamase activity of the Salmonella strains exhibiting ESBL phenotype was detected by biological, iodometric, spectrophotometry and nitrocefin assays. Results: Out of 202 S. enterica isolates, ESBLs phenotype was detected among 3.4% (7/202) of the strains. bla TEM-1 and bla CTX-M-15 were among the frequent β -lactamase genes. Detection of bla TEM-169 in S. enterica serovar Typhimurium and S. enterica serovar Bredeney and bla PER-1 in S. enterica serovar Infantis was a new finding in this experiment. Location of bla CTX-M-15 / bla TEM-169 / bla PER-1 genes on plasmid was confirmed in a transformation experiment. While crude extracts of the enzymes from each strain showed higher activity against cephalothin and cefotaxime, the lowest activity was detected against ceftazidime. The greatest synergistic activity was seen in a strain of S. enterica that carried bla CTX-M-15 and bla PER-1 genes compared with those presenting bla CTX-M-15 / bla TEM-169 or bla CTX-M-15 / bla TEM-1 genotypes. Conclusions: The results show dissemination of ESBLs encoding genes and their combined activity among different serovars of S. enterica that are a threat for future treatment options.