The emergence and spread of multidrug-resistant Salmonella enterica (S. enterica) to humans through food of animal origin are considered a major global public health concern. Currently, little is known about the prevalence of important antimicrobial resistance genes in S. enterica from retail food in Africa. Therefore, the screening and characterization of the extended-spectrum β-lactamase (ESBL) and plasmid-mediated quinolone resistance (PMQR) genes in S. enterica isolated from retail meats and slaughterhouses in Egypt were done by using PCR and DNA sequencing techniques. Twenty-eight out of thirty-four (82.4%) non-duplicate S. enterica isolates showed multidrug-resistance phenotypes to at least three classes of antimicrobials, and fourteen (41.2%) exhibited an ESBL-resistance phenotype and harbored at least one ESBL-encoding gene. The identified β-lactamase-encoding genes included bla_CTX-M-1, bla_CTX-M-3, bla_CTX-M-13, bla_CTX-M-14, bla_CTX-M-15, and bla_SHV-12 (ESBL types); bla_CMY-2 (AmpC type); and bla_TEM-1 and bla_OXA-1 (narrow-spectrum types). PMQR genes (included qnrA, qnrB, qnrS, and aac(6′)-Ib-cr) were identified in 23 (67.6%) isolates. The presence of ESBL- and PMQR-producing S. enterica with a high prevalence rate in retail meats and slaughterhouses is considered a major threat to public health as these strains with resistance genes could be transmitted to humans through the food chain.

Imported animals, especially those from developing countries, may constitute a potential hazard to native animals and to public health. In this study, a new flock of lesser flamingos imported from Tanzania to Hiroshima Zoological Park were screened for multidrug-resistant Gram-negative bacteria, integrons and antimicrobial resistance genes. Thirty-seven Gram-negative bacterial isolates were obtained from the flamingos. Seven isolates (18.9%) showed multidrug resistance phenotypes, the most common being against: ampicillin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole and nalidixic acid. Molecular analyses identified class 1 and class 2 integrons, β-lactamase-encoding genes, bla _TEM-1 and bla _CTX-M-2 and the plasmid-mediated quinolone resistance genes, qnrS and qnrB. This study highlights the role of animal importation in the dissemination of multidrug-resistant bacteria, integrons and antimicrobial resistance genes from one country to another.

The present study was designed to investigate the presence of genes that conferred resistance to antimicrobials among Enterobacteriaceae that were isolated from diarrhoeic calves. A total of 120 faecal samples were collected from diarrhoeic calves that were raised in Kafr El-Sheikh governorate, Egypt. The samples were screened for Enterobacteriaceae. A total of 149 isolates of bacteria were recovered and identified; Escherichia coli was found to be the most overwhelming species, followed by Citrobacter diversus, Shigella spp., Serratia spp., Providencia spp., Enterobacter spp., Klebsiella pneumoniae, Proteus spp., Klebsiella oxytoca, and Morganella morganii. All isolates were tested for susceptibility to 12 antimicrobials; resistant and intermediately resistant strains were screened by conventional polymerase chain reaction for the presence of antimicrobial resistance genes. Of the 149 isolates, 37 (24.8%) exhibited multidrug resistant phenotypes. The most prevalent multidrug resistant species were E. coli, C. diversus, Serratia spp., K. pneumoniae, Shigella spp., Providencia spp., and K. oxytoca. Class 1 integrons were detected in 28 (18.8%) isolates. All isolates were negative for class 2 integrons. The bla_TEM gene was identified in 37 (24.8%) isolates, whereas no isolates carried the bla_CTX-M gene_. The florfenicol gene (floR) was detected in two bacterial isolates (1.3%). The findings of this study reveal that calves may act as potential reservoirs of multidrug resistant bacteria that can be easily transmitted to humans.

Bacterial reverse transcriptase coding gene (RT) is essential for the production of a small satellite DNA‐RNA complex called multicopy single‐stranded DNA (msDNA). In this study, we found a novel retron, retron‐Vmi1 (Vm85) from Vibrio mimicus. The retron is comprised of the msr‐msd region, orf323, and the ret gene, a genetic organization similar to Salmonella's retron‐Sen2 (St85). The protein sequence of the RNA‐directed DNA polymerase (RT‐Vmi1) is highly homologous to the RTs of Vibrio metoecus, Vibrio parahaemolyticus, and Vibrio vulnificus. Phylogenetic and protein sequence similarity analysis of retron‐Vmi1 ORF323 and RT revealed a close relatedness to retron‐Sen2. We found that retron‐Vmi1 was inserted in the dusA gene, similar to the insertion of the retron‐Vpa1 (Vp96) of V. parahaemolyticus AQ3354, suggesting that retrons can be transferred via the tRNA gene. These results are the first convincing evidence that retron is moving across species. The neighboring genes of retron‐Vmi1 shared high homology with the genetic environment of V. parahaemolyticus and V. vulnificus retrons. We also found two junction points within the retron‐Vmi1 and the dusA gene suggesting that retron‐Vmi1 was inserted into this site in a two‐step manner.

A class 1 integron was detected in a single multidrug-resistant strain of enterotoxigenice Escherichia coli (ETEC) O159 after examination of 23 clinical E. coli isolates. This isolate was resistant to streptomycin, kanamycin, gentamicin, chloramphenicol and ampicillin. Sequencing of the class 1 integron identified three-gene cassettes. The first is the streptothricin acetyltransferase gene, sat, which confers resistance to streptothricin. The second is an ORF whose product is a putative phosphoserine phosphatase (PSP), and the last is an aminoglycoside adenyltransferase gene, aadA2, which confers resistance to streptomycin and spectinomycin. The putative PSP gene product was found to be 39%, 38%, 28%, and 27% identical to PSP gene products of Vibrio vulnificus CMCP6, V. vulnificus YJ016, Pseudomonas syringae, and P. aeruginosa, respectively. Southern-blot hybridization showed that this integron is located on a 90 kb plasmid. This is the first report identifying a putative PSP gene in an integron.