Antimicrobial Resistance and Genetic Diversity of Salmonella Serotypes Recovered from Edible Pork Offal from Korea.

Although edible offal can be easily contaminated with foodborne bacteria and regarded as important transfers of antimicrobial resistance to humans, the characterization of bacteria from edible offal have not been researched sufficiently. This study is the first to focus on the molecular characterization of Salmonella isolated from edible pork offal. From a total of 52 Salmonella isolates from edible pork offal, 44 (80.7%) were resistant to at least one antimicrobial agent and 24 (46.2%) exhibited multidrug resistance (MDR). All MDR Salmonella were also resistant to ß-lactams and 12 (50.0%) of the isolates were positive for blaTEM-1. Eleven (68.8%) of the 16 gentamicin-resistant isolates harbored the ant(2'')-I gene. Among 18 tetracycline-resistant isolates, tetA and tetB genes were found in 9 (50.0%) and 3 (16.7%) isolates, respectively. The sul1 gene was identified in 9 (81.8%) of 11 trimethoprim/sulfamethoxazole-resistant isolates, and the cmlA gene was identified in only 2 (18.1%) among 11 chloramphenicol-resistant isolates. Eighteen (75.0%) of the 24 MDR Salmonella were identified as containing class 1 integrons, within which dfrA12-aadA2 (55.6%) was the most prevalent resistance gene cassettes. Twenty-one (87.5%) of the MDR isolates were also found to have the plasmid replicons. Replicon B/O (41.7%) was the most prevalent replicon types. These results suggest that edible pork offal can become a reservoir that not only harbors MDR Salmonella, but also contributes to their dissemination through cross-contamination processes.

Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Edible Offal in Korea.

HIGHLIGHTS: Edible offal is significantly contaminated by antimicrobial-resistant Escherichia coli. E. coli from edible offal is harboring various antimicrobial resistance and virulence genes. Improvements in hygienic conditions of edible offal production is required.

Molecular characteristics of extended-spectrum and plasmid-mediated AmpC ß-lactamase-producing Escherichia coli isolated from commercial layer in Korea.

In the poultry industry, commercial layer farms play an important role in meeting the protein demand through the supply of eggs. However, the risk of contamination by ß-lactamase-producing Escherichia coli in eggs laid by commercial chickens is significant. In this study, we investigated the rate of extended-spectrum ß-lactamase (ESBL) and plasmid-mediated AmpC (pAmpC) ß-lactamase-producing E. coli isolated from layer hens and characterized their molecular background. Among the 92 cefotaxime-resistant E. coli isolates, 66 (71.7%) were identified as multidrug resistant and 29 showed phenotypic and genotypic characteristics of ß-lactamase-producing E. coli. The ESBL/pAmpC genes blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, and blaCMY-2 were detected in 1, 6, 5, and 4 isolates, respectively. The non-ESBL/pAmpC gene blaTEM-1 was found in 16 isolates. Three isolates harbored both blaTEM-1 and blaCTX-M-14 genes. A total of 12 isolates also carried class 1 integrons, with 3 different gene cassette arrangements found in 8 of these isolates. A pulsed-field gel electrophoresis (PFGE) analysis of the 29 ß-lactamase-producing E. coli isolates revealed that 4 PFGE patterns were consistent with the ß-lactamase gene and layer farm origin, and showed a similar antibiotic resistance pattern. Our results suggest that comprehensive surveillance and more prudent use of third-generation cephalosporins in commercial layer farms is necessary to prevent the dissemination of ESBL/pAmpC-producing E. coli.

Characteristics of cephalosporin-resistant Salmonella isolates from poultry in Korea, 2010-2017.

Cephalosporins are the key drugs for the treatment of salmonellosis. Resistance to cephalosporins in Salmonella spp. has become a serious public health concern worldwide. Although the sales of cephalosporins have increased by five times from 2008 to 2016 in Korea, limited information is available on cephalosporin resistance in Korea. Therefore, we aimed to investigate the trends in prevalence and characteristics of cephalosporin-resistant Salmonella isolates from poultry in Korea in the period between 2010 and 2017. A total of 141 Salmonella isolates were collected from various poultry industry sources, and 38 (27.0%) among them showed resistance to cephalosporins. In particular, resistance to the following cephalosporins increased significantly over the seven-year period cephalothin (from 5.0% to 29.2%), cephalexin, cefuroxime, cefotaxime, and ceftazidime (from 0% to 25.0%), and cefepime (from 0% to 12.5%). In addition, 12 isolates carried a ß-lactamase gene. A non-extended-spectrum ß-lactamase (ESBL) and plasmid-mediated AmpC ß-lactamase (pAmpC) gene, blaTEM-1, was found in three isolates in the periods of 2010 to 2011 and 2012 to 2013, respectively. The blaCTX-M-79 (n = 4) and blaCTX-M-15 (n = 1) for ESBL genes and blaCMY-2 (n = 1) for pAmpC genes were only present in the 2016-2017 period. All ESBL/pAmpC-positive isolates had high minimum inhibitory concentrations for most cephalosporins and showed multi-drug resistance. In a conjugation experiment, the transfer of blaCTX-M-79 and blaCMY-2 genes was confirmed in transconjugants, which showed similar pattern of antibiotic resistance. This demonstrates that ESBL/pAmpC-producing Salmonella isolates might be transmitted to humans through contaminated poultry products. These findings suggest the need for the development of monitoring program and the guidelines for prudent use of antimicrobial agents in the poultry industry in Korea.

Characteristics of third-generation cephalosporin-resistant Salmonella from retail chicken meat produced by integrated broiler operations.

Integrated broiler operations, which control and operate vertically through all phases of the chicken industry, have applied biosecurity and sanitation practices, housing technologies, feeding regimens, and antibiotic applications in different ways to improve food safety. The objective of this study was to compare the prevalence and antimicrobial resistance profiles of Salmonella isolates recovered from 6 different integrated broiler operations and to analyze the characteristics of extended-spectrum ß-lactamase (ESBL)- and plasmid-mediated AmpC ß-lactamase (pAmpC)-producing Salmonella isolates. Among 336 chicken meat samples, 57 were observed to be positive for Salmonella. However, the prevalence varied from 6.8% to 45.8% in chicken meat, indicating variations in Salmonella occurrence among the operations. Salmonella Albany was the dominant serovar, followed by Salmonella Virchow. In the antimicrobial resistance test, nalidixic acid-resistant isolates were the most prevalent (73.7%), followed by isolates resistant to ampicillin (49.1%) and tetracycline (42.1%). Among 14 third-generation cephalosporin-resistant isolates, 9 (64.3%) ESBL/pAmpC-producing isolates were only obtained from 2 operations: blaCTX-M-15 (n = 7) and blaCTX-M-79 (n = 1) for ESBL genes and blaCMY-2 (n = 1) for pAmpC. All ESBL/pAmpC-positive isolates exhibited high minimum inhibitory concentrations (≥128 µg/mL) of most cephalosporins and showed multidrug resistance. The transfer of ESBL/pAmpC genes was confirmed in transconjugants, which had the same genes and similar resistance patterns as those of the donor. Our findings suggest that Salmonella with resistance to third-generation cephalosporins can now be found in association with integrated broiler operations, providing data to support the development of monitoring and prevention programs for the development and spread of antimicrobial resistance in integrated broiler operations.

Molecular characterization of erythromycin and tetracycline-resistant Enterococcus faecalis isolated from retail chicken meats.

Enterococcus faecalis is a ubiquitous intestinal bacterium in human and animals that can easily acquire antimicrobial resistance, which allows it to play the role of an antimicrobial resistance indicator. The objectives of this study were to characterize erythromycin and tetracycline-resistant E. faecalis isolated from retail chicken meats. A total of 149 among 335 E. faecalis isolates from 7 integrated broiler operations showed the simultaneous resistance to erythromycin and tetracycline, and more than 50% among 149 isolates showed multidrug resistance. The most common resistance genes were ermB (96.0%, 143 isolates) related with macrolides resistance, and tet(M) (95.3%, 142 isolates) and tet(L) (89.3%, 133 isolates) related with tetracycline resistance. Furthermore, 140 (93.9%) isolates simultaneously possessed ermB, and tet(L) and/or tet(M) genes. Eight isolates with transposon of the Tn916/1545-like were detected, which also carried ermB and tet(M) genes. The most prevalent of virulence genes were gelE (142 isolates, 95.3%), ace (137 isolates, 91.9%), and efaA (120 isolates, 80.5%). Also, 5 E. faecalis isolates successfully transferred antimicrobial and virulence genes to E. faecalis FA2-2. Therefore, the antimicrobial-resistant E. faecalis isolates as well as their corresponding genes and mobile genetic elements, such as transposons may be disseminated nationwide by broiler operation system in Korea.

Characteristics of High-Level Ciprofloxacin-Resistant Enterococcus faecalis and Enterococcus faecium from Retail Chicken Meat in Korea.

Genes encoding ciprofloxacin resistance in enterococci in animals may be transferred to bacteria in the animal gut and to zoonotic bacteria where they could pose a human health hazard. The objective of this study was to characterize antimicrobial resistance in high-level ciprofloxacin-resistant (HLCR) Enterococcus faecalis and Enterococcus faecium isolated from retail chicken meat. A total of 345 enterococci (335 E. faecalis and 10 E. faecium) were isolated from 200 chicken meat samples. Of these, 85 E. faecalis isolates and 1 E. faecium isolate were confirmed as HLCR enterococci. All 86 HLCR enterococci displayed gyrA- parC point mutations consisting of S83I-S80I (94.2%, 81 isolates), S83F-S80I (2.3%, 2 isolates), S83Y-S80I (2.3%, 2 isolates), and S83Y-S80F (1.2%, 1 isolate). Sixty-one (72.9%) of the 86 HLCR enterococci showed multidrug resistance to three to six classes of antimicrobial agents. Multilocus sequence typing revealed that E. faecalis had 17 different sequence types (ST) and E. faecium had 1 different ST, with ST256 observed most often (44 isolates, 51.8%). Although these results cannot exclude the possibility that pathotypes of enterococci isolated from chicken might represent transmission to or from humans, the foodborne HLCR E. faecalis indicated that the food chain is a potential route of enterococcal infection in humans.

Comparative genetic characterization of third-generation cephalosporin-resistant Escherichia coli from chicken meat produced by integrated broiler operations in South Korea.

Vertical integration of the broiler industry allows producers to combine different biosecurity and sanitation practices, housing technologies, and feeding regimens to improve food safety. The objectives of this study were to determine the antimicrobial resistance pattern of ß-lactamase-producing E. coli and to compare the characteristics of E. coli recovered from 7 different integrated broiler operations in South Korea. Among 200 chicken meat samples, 101 were observed to be positive for E. coli. However, the prevalence varied from 37.5% to 75.0% in chicken meats from different operations, indicating variation in E. coli occurrence among the operations. Among 101 isolated E. coli from chicken meat, 59 were identified third-generation cephalosporin-resistant E. coli and recovered from 7 different operations. A high proportion of the E. coli isolates were resistant to penicillins (89.8%), quinolones (81.4%). Among 59 third-generation cephalosporin-resistant E. coli isolates, 29 showed phenotypic and genotypic characteristics of ß-lactamase-producing E. coli. Prevalence of bla gene, blaCTX-M-1, blaCTX-M-14, blaCMY-2, and blaTEM-1, were identified in 2, 4, 8, and 16 E. coli isolates respectively and only one E. coli had both genes, blaTEM-1 and blaCTX-M-1. Pulsed-field gel electrophoresis (PFGE) analysis was performed on 29 ß-lactamase-producing E. coli isolates. In PFGE, E. coli included 7 PFGE patterns showing the same operation and an accorded both resistance to ß-lactam antibiotics and presence of the bla-gene. Our findings suggest that E. coli with resistance to third-generation cephalosporins can now be found in association with integrated broiler operations, providing the data to support the development of monitoring and preventing program in integrated operations.

Differentially displayed genes with oxygen depletion stress and transcriptional responses in the marine mussel, Mytilus galloprovincialis.

Hypoxic events affecting aquatic environments have been reported worldwide and the hypoxia caused by eutrophication is considered one of the serious threats to coastal marine ecosystems. To investigate the molecular-level responses of marine organisms exposed to oxygen depletion stress and to explore the differentially expressed genes induced or repressed by hypoxia, differential display polymerase chain reaction (DD-PCR) was used with mRNAs from the marine mussel, Mytilus galloprovincialis, under oxygen depletion and normal oxygen conditions. In total, 107 cDNA clones were differentially expressed under hypoxic conditions relative to the control mussel group. The differentially expressed genes were analyzed to determine the effects of hypoxia. They were classified into five functional categories: information storage and processing, cellular processes and signaling, metabolism, predicted general function only, and function unknown. The differentially expressed genes were predominantly associated with cellular processing and signaling, and they were particularly related to the signal transduction mechanism, posttranslational modification, and chaperone functions. The observed differences in the DD-PCR of 10 genes (encoding elongation factor 1 alpha, heat shock protein 90, calcium/calmodulin-dependent protein kinase II, GTPase-activating protein, 18S ribosomal RNA, cytochrome oxidase subunit 1, ATP synthase, chitinase, phosphoglycerate/bisphosphoglycerate mutase family protein, and the nicotinic acetylcholine receptor) were confirmed by quantitative RT-PCR and their transcriptional changes in the mussels exposed to hypoxic conditions for 24-72 h were investigated. These results identify biomarker genes for hypoxic stress and provide molecular-level information about the effects of oxygen depletion on marine bivalves.

Spinal cord stimulator malfunction caused by radiofrequency neuroablation -A case report-.

The implantation of spinal cord stimulators (SCSs) to treat chronic intractable pain is steadily increasing. And there is an increased likelihood of instances where other therapies or procedures are found to interfere with SCS function, which in turn may result in pain. Since SCS utilize electric impulses as well as magnets, special considerations need for patients with a SCS in situ who require these procedures. The present report describes a case where radiofrequency (RF) ablation of the third occipital nerve resulted in spontaneous activation of a cervical SCS device.