Short communication Possible transfer of plasmid mediated third generation cephalosporin resistance between Escherichia coli and Shigella sonnei in the human gut Harunur Rashid a,b,⇑ , Mahbubur Rahman a a International Center for Diarrheal Disease Research, Bangladesh b Department of Cell Biology, University of Alabama at Birmingham, USA article info Article history: Received 9 August 2014 Received in revised form 17 November 2014 Accepted 22 November 2014 Available online 26 November 2014 Keywords: ESBL Shigella sonnei Escherichia coli MDR R-plasmid Third generation cephalosporin abstract Choice of antibiotic for treatment of serious bacterial infection is rapidly diminishing by plasmid medi- ated transfer of antibiotic resistance. Here, we report a possible horizontal transfer of plasmid carrying third-generation-cephalosporin (TGC) resistance between Escherichia coli and Shigella sonnei. Two differ- ent types of colonies were identified in MacConkey agar plate from a faecal specimen collected from a patient with shigellosis. The colonies were identified as E. coli and S. sonnei. Both of the isolates were resistant to ampicillin, chloramphenicol, co-trimoxazole, erythromycin, azithromycin, nalidixic acid, ceftriaxone, cefixime, ceftazidime, cefotaxime and susceptible to co-amoxiclave, amikacin, imipenam, astreonam, levofloxacin, moxifloxacin, mecillinam. These two strains were positive for extended spectrum b-lactamase. We were able to transfer ESBL producing property from both ceftriaxone-resistant isolates to the ceftriaxone susceptible recipient E. coli K12 and S. sonnei. Plasmid profile analysis revealed that the first-generation E. coli K12 and S. sonnei transconjugants harbored a 50 MDa R plasmid, as two-parent ESBL-producing S. sonnei and E. coli strains. Similar patterns of ESBL producing plasmid and transferable antimicrobial phenotype suggests that the ESBL producing plasmid might transferred between E. coli and S. sonnei through conjugation in the human gut. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Antimicrobial therapy for bacterial dysentery, aimed to resolve diarrhea or reducing duration, risk of complications, as well as spread of infection, is routinely used in Bangladesh like many other countries (Radice et al., 2001). Abundant and inappropriate use of antimicrobials causes selection of resistant bacterial strains and may facilitate to develop resistance against the frequently used antibiotics (Tenover, 2006). Thus, multi-drug resistant [MDR; resistant to P3 different classes of antimicrobials such as ampicil- lin, trimethoprim-sulphamethoxazole (TMP-SMZ), nalidixic acid] Shigella isolates are common in many countries (Rahman et al., 2007; Prats et al., 2000; Replogle et al., 2000). Therefore, third gen- eration cephalosporins (TGC) were used for the treatment of MDR Shigella infections. Bacterial pathogens resistant to third generation cephalosporin due to the extended spectrum b-lactamase (ESBL) are also resistant to all b-lactams except cephamicins and carbapenems has become a worldwide problem (Bradford, 2001). Following the first report in 1985 in Germany, so far more than 150 different ESBLs have been described. Although various types of ESBLs have been found worldwide in many different genera of Enterobacteriaceae and Pseudomonas aeruginosa,(Bradford, 2001), only a few reports are on ESBL producing Shigella (Rahman et al., 2004; Radice et al., 2001; Ahmed and Kundu, 1999; Fortineau et al., 2001; Pai et al., 1960). ESBL producing plasmid was shown to be transferable to Escherichia coli K12 and also in the wild type Shigella strains in vitro (Rahman et al., 2004). In vivo transfer of resistance factor between enterobacterial populations have been demonstrated in experimental animals by several studies (Salzman and Klemm, 1968; Walton, 1966). In human, a number of investigators have tried but not succeeded to demonstrate the transfer of R plasmid (Anderson, 1975a; Smith, 1969). Therefore, in vivo transfer of ESBL producing R plasmid in the human intes- tine is an especial interest for the researchers in this field. In the current study, we described a possible natural transfer of ESBL pro- ducing plasmid between E. coli and Shigella sonnei in the human gut with shigellosis. http://dx.doi.org/10.1016/j.meegid.2014.11.023 1567-1348/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: International Center for Diarrheal Disease Research, Bangladesh and Department of Cell Biology, University of Alabama at Birmingham, USA. Tel.: +1 205 503 2967; fax: +1 2059965109. E-mail address: hrashid07@gmail.com (H. Rashid). Infection, Genetics and Evolution 30 (2015) 15–18 Contents lists available at ScienceDirect Infection, Genetics and Evolution journal homepage: www.elsevier.com/locate/meegid