Characterization of the First Extended-Spectrum β-Lactamase–Producing NontyphoidalSalmonellaStrains Isolated in Tehran, Iran

Abstract

The infections caused by Salmonella remain a significant public health problem throughout the world. beta-Lactams and fluoroquinolones are generally used to treat invasive Salmonella infections, but emergence and spread of antibiotic-resistant strains are being increasingly notified in many countries. In particular, detection of extended-spectrum beta-lactamases (ESBLs) in Salmonella spp. is a newly emerging threat worldwide. This study was carried out to characterize beta-lactamase-producing Salmonella strains identified in Tehran, Iran. Over the 2-year period from 2007 to 2008, 6 of 136 Salmonella isolates recovered from pediatrics patients, including three Salmonella enterica serotypes Enteritidis (S. Enteritidis) and three S. Infantis, showed an ESBL-positive phenotype. Polymerase chain reaction and sequencing were used to identify the genetic determinants responsible for ESBL phenotypes. The Salmonella isolates were also compared by pulsed-field gel electrophoresis. All ESBL-producing strains, but one, carried the bla(CTX-M-15) gene. Moreover, three of four strains that proved to be positive for a bla(TEM) gene were producing a TEM-1 beta-lactamase. Two strains of S. Infantis tested positive for a previously unidentified CTX-M and TEM ESBL, respectively. All ESBL-producing strains carried the insertion sequence ISEcp1 gene. Except for one strain of serotype Infantis, all strains were able to transfer the ESBL determinants by conjugation. Distinct, but closely related, pulsed-field gel electrophoresis patterns were observed among the strains belonging to both serotypes. This study reports for the first time the emergence and characterization of ESBL-producing S. Enteritidis and Infantis strains in Iran.

Antibiotic Resistance in Extended Spectrum Beta-Lactamases (Esbls) Salmonella Species Isolated from Patients with Diarrhoea in Calabar, Nigeria

“…The emergence and spread of antibiotic resistant strains particularly the detection of the Extended Spectrum Beta-lactamases (ESBLs) Salmonella species, is fast becoming an emerging world threat [1]. ESBLs frequently occur in K. pneumoniae but recent studies have increasingly reported its occurrence in the Salmonella specie and other gram-negative organisms [2,3].…”

“…cefuroxime, third generation cephalosporin and aztreonam) with cephamycins and carbapenems as exceptions. Most ESBLs belong to the Ambler class "A" β-lactamases and are inhibited by β-lactamase inhibitors (clavulanate, sulbactam and tazobactam) [1]. ESBLs are plasmid-mediated and as a result, are easily transmitted among members of the Enterobacteriaceae family [2].…”

Association of Three Plasmid-Encoded spv Genes Among Different Salmonella Serotypes Isolated from Different Origins

“…Members of the genus Salmonella infect a wide variety of hosts and cause diseases in many animal species and in human beings according to their antigenic profiles [2,3]. Salmonellosis is associated with medium to severe morbidity and even mortality in farm animals, representing major economic losses in the food and animal industries [4].…”

First CTX-M type ß–lactamase-Producing and Ciprofloxacin Resistant Salmonella Infection Acquired by a Child in IRAN

“…Increasing occurrence of antimicrobial resistant Salmonella strains have complicated the treatment process. In particular, detection of fluoroquinolon and expanded spectrum cephalosporin's resistant Salmonella strains is a newly emerging threat in many countries (3). In this study, we report a ciprofloxacin and expanded spectrum cephalosporin's resistant Salmonella Enteritidis isolated from a child with severe gastroenteritis.…”

“…The isolate was investigated for ESBL production using the double disk synergy test according to published methods (3). The genes responsible for the ESBL phenotype (blaTEM, blaSHV, blaCTX-M) were identified by PCR assay using primers and conditions reported previously (3). By PCR assays the Salmonella Enteritidis isolate was found to carry class 1 integrons (Figure 1).…”