C olistin is considered a last resort for the treatment of infections caused by carbapenemase-producing members of the family Enterobacteriaceae. Recently, a transferable plasmid conferring resistance to colistin was discovered in Escherichia coli and Klebsiella pneumoniae from China (1) and was then reported in various bacteria from many other countries (2-4). This spread of antibiotic resistance heralds a return to the preantibiotic era, especially with no new antibiotics in the pipeline. The plasmid-mediated colistin resistance gene mcr-1 has been identified mainly in bacterial species from animals and animal products (pork and chicken meat) (1, 2). However, it was also detected in humans, i.e., patients (1-4), asymptomatic people (5), and some people by whom it was community acquired (6). Therefore, we used PCR and DNA sequencing to screen for the presence of mcr-1 in 241 nonduplicate Gram-negative clinical bacterial isolates collected from hospitals in different cities in Egypt during 2015. A universal primer pair, CLR5-F (5=-CGGTCAGTCCGTT TGTTC-3=) and CLR5-R (5=-CTTGGTCGGTCTGTAGGG-3=), was used for screening as previously described (1). In addition, the entire mcr-1 region was amplified and sequenced with MCR-1-F2 (5=-CTCATGATGCAGCATACTTC-3=) and MCR-1-R2 (5=-CGAATGGAGTGTGCGGTG-3=), which were based on the consensus sequences that flank mcr-1 (GenBank accession no. KP347127). Analysis showed that mcr-1 was present in only one E. coli isolate (SP-1), which was from the sputum of a patient with bacteremia who was hospitalized in the intensive care unit of a Cairo City hospital with no history of traveling abroad. The MIC of both colistin and polymyxin B for this isolate was 16 mg/liter. E. coli SP-1 had phenotypic resistance to colistin, ciprofloxacin, nalidixic acid, kanamycin, tetracycline, chloramphenicol, ceftriaxone, ampicillin, and cefotaxime but was susceptible to carbapenems. Multilocus sequence typing (MLST) indicated that E. coli SP-1 belonged to sequence type 1011 (ST1011), which differed from sequence types identified for clinical E. coli isolates harboring mcr-1 in Denmark (ST744) (2) and Cambodia (ST354) (3). According to the MLST database (http://mlst.ucc.ie/mlst/mlst /dbs/Ecoli), E. coli ST1011 was reported in humans in Egypt and in cats and swine in Germany. Of note, E. coli ST1011 was detected previously as an avian fecal E. coli strain in Egypt (7) and it was found to be shared by avian pathogenic E. coli and human extraintestinal pathogenic E. coli by phylogenetic grouping in Brazil (8). Also, it was found as CTX-M-64-harboring E. coli isolates from chickens in China (9). Therefore, E. coli ST1011 may have potential zoonotic importance. Southern hybridization showed that mcr-1 was located on a plasmid of Ͼ90 kb. This plasmid was successfully transferred to E. coli J53 recipient cells through conjugation.

Campylobacter jejuni is the leading cause of foodborne bacterial gastroenteritis in humans worldwide. Contaminated chickens and their products are the main sources of human campylobacteriosis. Therefore, this study aimed to detect the genotypic and virulence genes‘ profiles of multi-drug resistant (MDR) C. jejuni isolates and to assess the effects of sub-inhibitory concentrations (SICs) of eugenol and beta-resorcylic acid on the virulence of avian MDR C. jejuni isolates. These isolates were clustered together with the human isolates via enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) fingerprinting. A total of 345 samples were collected from human stool (100) and different chicken (245) samples in Sharkia Governorate, Egypt. Conventional phenotypic methods identified 113 isolates (32.8%) as C. jejuni, and all C. jejuni isolates were MDR and resistant to erythromycin and ampicillin. The genes virB11, wlaN, and flaA were detected in 52%, 36% and 100% strains, respectively. ERIC-PCR yielded 14 profiles and five main clusters. Interestingly, human and chicken C. jejuni isolates were clustered together in ERIC-PCR clusters II-V, which confirmed the genetic relatedness between the isolates from both origins. Beta-resorcylic acid and eugenol inhibited the invasion of C. jejuni isolates to chicken intestinal cells by 41.66–38.19% and 31.94–29.16%, respectively, and minimized the transcription of flaA, virB11, and wlaN genes in the tested isolates by real-time quantitative reverse transcription PCR (qRT-PCR). In essence, eugenol and beta-resorcylic acid are promising natural antimicrobials for minimizing the virulence of MDR C. jejuni in chickens, thereby managing human campylobacteriosis.

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