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Plasmid-mediated quinolone resistance (PMQR) genes and mobile colistin resistance (MCR) genes in Escherichia coli ( E. coli ) have been widely identified, which is considered a global threat to public health. In the present study, we conducted an analysis of MCR genes ( mcr-1 , mcr-2 , mcr-3 , mcr-4 , and mcr-5 ) and PMQR genes [ qnrA , qnrB , qnrC , qnrD , qnrE1 , qnrVC , qnrS , aac(6')-Ib-cr , qepA , and oqxAB ] in E. coli from China, 1993-2019. From the 3,663 E. coli isolates examined, 1,613 (44.0%) tested positive for PMQR genes, either individually or in combination. Meanwhile, 262 isolates (7.0%) carried the MCR genes. Minimum inhibitory concentration (MIC) analyses of 17 antibiotics for the MCR gene-carrying strains revealed universal multidrug resistance. Resistance to polymyxin varied between 4 μg/mL and 64 μg/mL, with MIC50 and MIC90 at 8 μg/mL and 16 μg/mL, respectively. In addition, fluctuations in the detection rates of these resistant genes correlated with the introduction of antibiotic policies, host origin, temporal trends, and geographical distribution. Continuous surveillance of PMQR and MCR variants in bacteria is required to implement control and prevention strategies.

Background: Inappropriate use of antibiotics in swine feed could cause accelerated emergence of antibiotic resistance genes, and agricultural application of swine waste could spread antibiotic resistance genes to the surrounding environment. Objectives: We investigated the distribution of plasmid-mediated quinolone resistance (PMQR) genes from swine feedlots and their surrounding environment. Methods: We used a culture-independent method to identify PMQR genes and estimate their levels in wastewater from seven swine feedlot operations and corresponding wastewater-irrigated farm fields. Concentrations of (fluoro)quinolones in wastewater and soil samples were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. Results: The predominant PMQR genes in both the wastewater and soil samples were qnrD, qepA, and oqxB, whereas qnrS and oqxA were present only in wastewater samples. Absolute concentrations of all PMQR genes combined ranged from 1.66 × 107 to 4.06 × 108 copies/mL in wastewater and 4.06 × 106 to 9.52 × 107 copies/g in soil. Concentrations of (fluoro)quinolones ranged from 4.57 to 321 ng/mL in wastewater and below detection limit to 23.4 ng/g in soil. Significant correlations were found between the relative abundance of PMQR genes and (fluoro)quinolone concentrations (r = 0.71, p = 0.005) and the relative abundance of PMQR genes in paired wastewater and agricultural soil samples (r = 0.91, p = 0.005). Conclusions: Swine feedlot wastewater may be a source of PMQR genes that could facilitate the spread of antibiotic resistance. To our knowledge, this is the first study to examine the occurrence of PMQR genes in animal husbandry environments using a culture-independent method. [ABSTRACT FROM AUTHOR]

Salmonella 4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium, which is responsible for global foodborne disease outbreaks. Here, 255 S. 4,[5],12:i:- strains isolated from humans (11.0%) or food-borne animals (89.0%) between 2010 and 2018 were examined. Tests of susceptibility to 19 antimicrobial agents using the broth micro dilution method showed that 99.2% (n = 253) of the isolates were resistant to at least one compound. Antibiotic susceptibility analysis demonstrated that 91.8% of the isolates were multidrug-resistant (MDR) strains with predominant resistance to tetracycline (90.6%), followed by resistance to ampicillin (86.3%), streptomycin (63.5%), chloramphenicol (62.7%), and trimethoprim-sulfamethoxazole (55.3%). The 5 major distinct patterns of multi-resistance were identified as R-type AST, R-type ACTSxt, R-type ACSTSxt, R-type ACGSTSxt and R-type ASTSxt. Among the PMQR genes examined in this study, oqxAB and aac (6')-Ib-cr were the most prevalent resistance genes in the multi-resistant isolates. Our findings highlight the prevalence of the resistance of S. 4,[5],12:i:- in some regions of China, and several common types of multidrug resistance phenotypes, to provide valuable information for epidemiological studies, risk management, and public health strategies. • Salmonella 4,[5],12:i:- was isolated from pigs, chickens, humans, geese and cats. • Multidrug resistance was detected in >91.8% of the S. 4,[5],12:i:- isolates. • The MDR patterns is comprehensive. • oqxAB and aac(6′)-Ib-cr were the common plasmid-mediated quinolone resistance genes. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is the leading cause of foodborne bacterial poisoning in China. The aim of this research is to conduct a study on the prevalence, virulence, and antimicrobial resistance of V. parahaemolyticus from different types of food samples in 12 different cities of China. Since fluoroquinolones are the major choice of treatment for V. parahaemolyticus infections, the genetic basis for fluoroquinolone resistance in V. parahaemolyticus were also investigated. V. parahaemolyticus was detected in 163 of the 784 food samples collected from 12 different cities in China, resulting in a prevalence of 20.79%. The prevalence of V. parahaemolyticus in ready-to-eat (RTE) food (4.96%) was much lower than those of shrimp (32.62%) and fish (22.00%). Virulence gene screening showed that 44 (27.00%) V. parahaemolyticus strains carried at least one virulence gene. Four isolates from shrimp and three isolates from fish contained both the virulence genes tdh and trh. In addition, the trh was firstly detected in one isolate collected from RTE food. All isolates exhibited relatively high resistance rates to ampicillin (82.21%), gentamicin (19.63%), and tetracycline (14.11%), while <10% of strains were resistant to ciprofloxacin (4.91%), levofloxacin (4.91%), and tetracycline (4.29%). Eight fluoroquinolone-resistant V. parahaemolyticus were selected to determine the molecular basis for fluoroquinolone resistance. These eight isolates belonged to three different types according to enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR). A Ser83Ile substitution in GyrA was deteted in seven fluoroquinolone-resistant strains, except V209 which harbored a Ser83Phe substitution in GyrA. Moreover, A Ser85Leu substitution in ParC was found in five isolates (V52, V53, V61, V163, and V209). Plasmid-mediated quinolone resistance (PMQR) genes were detected in all eight fluoroquinolone-resistant V. parahaemolyticus strains. This is the first report of Ser83Phe substitution in GyrA, qnrD and qnrS1 in V. parahaemolyticus. The information generated in this study will provide valuable information for risk assessment of V. parahaemolyticus infections and future control of antibiotic-resistant V. parahaemolyticus species in China. • The prevalence of V. parahaemolyticus in RTE foods was lower than those of seafoods. • 44 (27.00%) V. parahaemolyticus strains carried at least one virulence gene. • The virulence gene trh was firstly detected in one isolate collected from RTE foods. • Ser83Phe mutation in GyrA was identified in V. parahaemolyticus for the first time. • PMQR genes qnrD and qnrS1 were detected in V. parahaemolyticus for the first time. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance genes in aquaculture environments have attracted wide interest, since these genes pose a severe threat to human health. This study aimed to explore the possible mechanisms of the ciprofloxacin resistance of Vibrio parahaemolyticus (V. parahaemolytiucs) in aquaculture environments, which may have been affected by the biofertilizer utilization in China. Plasmid-mediate quinolone resistance (PMQR) genes, representative (fluoro)quinolones (FNQs), and ciprofloxacin-resistance isolates in biofertilizer samples were analyzed. The significantly higher abundance of oqxB was alarming. The transferable experiments and Southern blot analysis indicated that oqxB could spread horizontally from biofertilizers to V. parahaemolyticus , and two (16.7%) trans -conjugants harboring oqxB were provided by 12 isolates that successfully produced OqxB. To the best of our knowledge, this study is the first to report PMQR genes dissipation from biofertilizers to V. parahaemolyticus in aquaculture environments. The surveillance, monitoring and control of PMQR genes in biofertilizers are warranted for seafood safety and human health. • The prevalence of PMQR determinants in biofertilizers was first investigated. • The abundance of oqxB gene in biofertilizer is significantly high. • The dissipation of oqxB from biofertilizers to Vibrio was first discovered. • ARGs in biofertilizer could pose a risk in seafood safety and public health. [ABSTRACT FROM AUTHOR]