Detection of extended-spectrum β-lactamase (ESBL) and plasmid-borne blaCTX-M and blaTEM genes among clinical strains of Escherichia coli isolated from patients in the north of Iran

The aim of this study was to determine the prevalence of β-lactamase (TEM, SHV, OXA), extended-spectrum β-lactamase (ESBL) and genes encoding plasmid mediated resistance to quinolones (PMQR) in extended spectrum cephalosporin (ESC)-resistant Escherichia coli isolated from dog faeces from two shelters in the North-East of Romania. Eighty-eight faecal samples from healthy dogs were analysed by cultivation on Brilliance ESBL medium (Oxoid, UK), followed by phenotipic ESBL screening using combination disc test (CDT). Identification of the E. coli strains was performed by uidA/uspA gene PCR. Susceptibility testing was performed on Mueller-Hinton Agar, with β-lactam and non-β-lactam agents. Identification of β-lactamase genes (blaCTX-M, blaTEM, blaSHV, blaOXA) and PMQR genes (qnrA, qnrB and qnrS) was performed by PCR as previously described. Twenty eight ESC-resistant E. coli (31.81%) were obtained and (n=21/28, 75%) of these were confirmed as ESBLs and showed resistance to cefpodoxime (n=21/28, 75%), amoxicillin/clavulanic acid (n=19/21; 90.48%), and enrofloxacin (n=8/21; 38.09%). Predominant ESBL types were CTX-M-1 (n=15/17, 88.24%) and CTX-M-9 (n=2/17, 11.76%) enzymes. TEM and SHV enzymes were identified in 17.86% and 14.29% of the ESC-resistant isolates, whilst some isolates (n=4) carried only blaTEM and blaSHV. The prevalence of PMQR genes was 28.57% of the 28 ESC resistant isolates, consisting of qnrS (62.5%) and qnrB (37.5%). These findings indicate a high prevalence of ESBLs and PMQR associated resistance E. coli in the normal faecal microbiota of dogs from shelters, which carries the risk for dissemination of these resistance genes to other animals, human or the environment.

Download Full-text

Integron Content of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains over 12 Years in a Single Hospital in Madrid, Spain

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.5.1823-1829.2005 ◽

2005 ◽

Vol 49 (5) ◽

pp. 1823-1829 ◽

Cited By ~ 118

Author(s):

Elisabete Machado ◽

Rafael Cantón ◽

Fernando Baquero ◽

Juan-Carlos Galán ◽

Azucena Rollán ◽

...

Keyword(s):

Escherichia Coli ◽

Class 1 Integron ◽

Clinical Strains ◽

E Coli ◽

Class 1 Integrons ◽

Genetic Elements ◽

Extended Spectrum ◽

Low Diversity ◽

Class 1 ◽

Wide Dissemination

ABSTRACT The contribution of integrons to the dissemination of extended-spectrum β-lactamases (ESBL) was analyzed on all ESBL-producing Escherichia coli isolates from 1988 to 2000 at Ramón y Cajal Hospital. We studied 133 E. coli pulsed-field gel electrophoresis types: (i) 52 ESBL-producing clinical strains (C-ESBL) (16 TEM, 9 SHV, 21 CTX-M-9, 1 CTX-M-14, and 5 CTX-M-10); (ii) 43 non-ESBL blood clinical strains (C-nESBL); and (iii) 38 non-ESBL fecal isolates from healthy volunteers (V-nESBL). Class 1 integrons were more common among C-ESBL (67%) than among C-nESBL (40%) or V-nESBL (26%) (P < 0.001) due to the high number of strains with bla CTX-M-9 , which is linked to an In6-like class 1 integron. Without this bias, class 1 integron occurrence would be similar in C-ESBL and C-nESBL groups (47% versus 40%). Occurrence of class 2 integrons was similar among clinical and community isolates (13 to 18%). No isolates contained class 3 integrons. The relatively low rate of class 1 integrons within transferable elements carrying blaTEM (23%) or blaSHV (33%) and the absence of class 2 integrons in all ESBL transconjugants mirror the assembly of translocative pieces containing blaTEM or blaSHV on local available transferable elements lacking integrons. The low diversity of class 1 integrons (seven types recovered in all groups) might indicate a wide dissemination of specific genetic elements in which they are located. In our environment, the spread of genetic elements encoding ESBL has no major impact on the dispersion of integrons, nor do integrons have a major impact on the spread of ESBL, except when blaESBL genes are within an integron platform such as bla CTX-M-9 .

Download Full-text