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1.
BMC Infect Dis ; 19(1): 696, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31387542

RESUMO

BACKGROUND: Human norovirus is regarded as the leading cause of nonbacterial acute diarrhea in developing and developed countries. Among all genotypes, GII.4 has been the predominant genotype, but in East Asia, it was replaced by the GII.17 in 2014/2015. However, after the prevalence of new GII.17 variant in South China, a sharply increase in the number of norovirus infections associated with sporadic acute diarrhea was detected. In this study, we would investigate the prevalence and genetic diversity of noroviruses in the sporadic acute gastroenteritis cases in the post-GII.17 period in South China. METHODS: Norovirus was screened from 217 patients with sporadic acute gastroenteritis from August 2015 to October 2017 by reverse transcription-polymerase chain reaction. Then, two regions including the partial RNA polymerase and the capsid gene of positive samples were amplified and sequenced. Phylogenetic analyses were performed to determine norovirus genotypes. Complete VP1 sequences of GII.4 strains detected in this study were also amplified and subjected into evolutionary tracing analyses. RESULTS: A total of 43 (19.82%) norovirus samples were confirmed from 217 stool specimens, and it was found that GII.4 resurged as the new predominant variant, accounting for 76.74% (33/43) of positive samples. Only one local strain GZ2015-L550 was clustered with the contemporary GII.P16/GII.4-2012 recombinant variant, and other 32 local strains belonged to the clade with the GII.Pe/GII.4-2012 variant. Other genotypes including GII.17 (n = 4), GII.3 (n = 4), GII.8 (n = 1) and GI. 6 (n = 1) were also detected. Furthermore, all GII.4 strains were phylogenetic analyzed based on their capsid P2 subdomains. Combined with other reported 754 strains, the GII.4-2012 variant could be divided into two clades. Most GII.4 strains collected in 2016 and 2017 in this study (7/8) formed a new cluster A in Clade II with additional 103 contemporaneous strains. In addition, evolutionary tracing of the capsid P2 subdomain of this variant was also analyzed, and one specific amino acid substitutions (N373) was identified for Cluster A. CONCLUSION: In summary, this study confirmed a norovirus infection peak in the post-GII.17 period in South China, which was caused by the resurgence of the GII.4 variant.

2.
Arch Virol ; 164(10): 2627-2630, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31363923

RESUMO

A lytic bacteriophage, designated Vibrio phage vB_VpP_BA6, was isolated from sewage collected in Guangzhou, China. The double-stranded DNA genome of phage BA6 is composed of 50,520 bp with a G+C content of 41.77%. It possesses 64 open reading frames relating to phage structure, packaging, host lysis, DNA metabolism, and additional functions. Three tRNAs genes (encoding Pro, Ile and Trp) were detected. Comparison of its genomic features and phylogenetic analysis revealed that phage BA6 is a novel member of the family Podoviridae. This phage may represent a potential therapeutic agent against multidrug-resistant Vibrio parahaemolyticus.


Assuntos
Bacteriófagos/genética , Bacteriófagos/isolamento & purificação , Genoma Viral , Podoviridae/genética , Podoviridae/isolamento & purificação , Vibrio parahaemolyticus/virologia , Bacteriólise , Bacteriófagos/classificação , Bacteriófagos/crescimento & desenvolvimento , Composição de Bases , China , DNA/química , DNA/genética , Fases de Leitura Aberta , Filogenia , Podoviridae/classificação , Podoviridae/crescimento & desenvolvimento , RNA de Transferência/genética , Esgotos/virologia
3.
Int J Food Microbiol ; 308: 108290, 2019 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-31442712

RESUMO

The plasmid-mediated colistin resistance gene mcr-1 has been identified in various Enterobacteriaceae species, which poses a great challenge to the public health. The present study aimed to investigate the prevalence of mcr-1 in Vibrio parahaemolyticus isolated from food samples in China, and to conduct a comprehensive analysis on the molecular characterization of V. parahaemolyticus isolate carrying mcr-1-harboring plasmid. A total of 646 V. parahaemolyticus strains isolated from 2531 food samples collected in retail markets in 34 different cities in China were screened for colistin resistance. Of the 646 V. parahaemolyticus isolates tested, 25 (2.5%) exhibited colistin resistance. The mcr-1 gene was detected in one colistin-resistant V. parahaemolyticus isolate, VP181, obtained from a shrimp sample collected in Hong Kong. The mcr-1 gene was located on a transferable IncX4 plasmid with size of ~40 kb. A Class A ß-lactamase gene, blaCARB-17 and the plasmid-mediated quinolone resistance (PMQR) gene qnrVC5 were detected in the mcr-1-positive V. parahaemolyticus isolate VP181. Virulence gene assays indicated that tdh was detected in VP181 by PCR. This is the first report of the occurrence of plasmid-encoded mcr-1 in virulent V. parahaemolyticus strain. Our findings indicate horizontal transfer of this gene to non-Enterobacteriaceae gram-negative bacteria, which warrants further investigation because of the public health threat it poses.

4.
Food Microbiol ; 83: 86-94, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31202422

RESUMO

Spoilage bacteria seriously influence meat quality. In this study, the bacterial community, sensory scores, pH, and total volatile basic nitrogen (TVB-N) in refrigerated (4 °C) pork, the most commonly consumed meat in China, were investigated. In a high-throughput sequencing analysis of the V3-V4 region of the 16S rDNA gene, 259 bacterial genera were belonging to 21 phyla were identified. With the passage of time, the bacterial community diversity decreased. After 5 days, Pseudomonas, Acinetobacter and Photobacterium were dominant in refrigerated pork, especially Photobacterium, which rarely associated with meat spoilage. Our results suggest that these taxa contribute to refrigerated pork spoilage. During storage, pH and TVB-N showed similar trends. Additionally, total viable counts (TVC) increased steadily and sensory score decreased. On day 5, TVC, pH, TVB-N and sensory scores changed dramatically, and sensory scores indicating that the shelf life of refrigerated pork was less than 5 days. The predicted metabolic pathways, based o the data of 16S rDNA, indicated an abundant carbohydrate metabolism and amino metabolism in refrigerated pork. This study provides insight into the determinants of shelf life. Furthermore, it provides insight into the process involved in refrigerated pork spoilage.

5.
Int J Food Microbiol ; 304: 119-126, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31195259

RESUMO

Staphylococcus aureus encodes numerous toxins that are known or strongly suspected to cause specific diseases or symptoms. Panton-Valentine leukocidin (PVL) is one of these important toxins that is associated with high mortality rates. In our previous study, 1581 S. aureus strains were isolated from 4300 samples of retail foods obtained from most of the provincial capitals in China from 2011 to 2016. This study aimed to investigate the prevalence of PVL-positive S. aureus isolates from retail foods in China and characterize these isolates by antibiotic resistance testing, spa typing, multilocus sequence typing (MLST) and enterotoxin gene analyses. In total, seventy-two isolates (72/1581, 4.6%) possessed pvl genes, including 24.1% MRSA isolates (26/108) and 3.1% MSSA isolates (46/1473), covering different types of food. The strains were divided into seventeen sequence types (STs) and twenty-seven spa types, and 43.1% (31/72) of the PVL-positive S. aureus isolates belonged to CC59-t437. These isolates contained at least one of the following enterotoxin genes: sei (97.2%), sem (86.1%), seq (80.6%), seg (68.1%), sek (68.1%), seb (62.5%), sel (52.8%), sej (50.0%), seh (48.6%), sep (45.8%), sea (38.9%), ser (37.5%), sen (27.8%), sec (16.7%), see (16.7%), sed (6.9%), seo (6.9%) and seu (6.7%). A total of 87.5% of the S. aureus isolates (63/72) harboured the classic SE genes (sea, seb, sec, sed, and see), whereas all the S. aureus isolates harboured the genes of the egc cluster (seg, sei, sem, sen, seo, and seu). In antimicrobial susceptibility tests, 98.6% of the isolates (71/72) exhibited resistance to at least one antibiotic, including 47 multi-drug-resistant isolates. Resistance to penicillin (94.4%), erythromycin (83.4%), clindamycin (63.9%), kanamycin (61.1%), telithromycin (58.3%), streptomycin (51.4%), tetracycline (47.2%), chloramphenicol (27.8%), fusidic acid (27.8%) and other antibiotics (<20%) was observed. All the PVL-positive MRSA isolates belonged to CC59-t437, which is the predominant type of community-associated (CA)-MRSA in China. The presence of these isolates in food represents a potential health risk for consumers and warrants further attention.


Assuntos
Toxinas Bacterianas/genética , Farmacorresistência Bacteriana Múltipla/genética , Enterotoxinas/genética , Exotoxinas/genética , Leucocidinas/genética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/epidemiologia , Antibacterianos/farmacologia , China/epidemiologia , Contaminação de Alimentos/análise , Microbiologia de Alimentos/métodos , Doenças Transmitidas por Alimentos/microbiologia , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Tipagem de Sequências Multilocus , Prevalência , Infecções Estafilocócicas/microbiologia
6.
J Med Virol ; 91(10): 1759-1764, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31180139

RESUMO

Human sapovirus (SaV) is an important viral agent for acute diarrhea worldwide, but timely prevalence data of human SaV in South China are still lacking. In this study, a 4-year surveillance was conducted to characterize the prevalence and genetic characteristics of the circulating SaV associated with sporadic diarrhea in South China. From November 2013 to October 2017, 569 fecal samples from patients with acute diarrhea were collected. SaV was detected in 11 samples with a positive rate of 1.93%. Three human genogroups of GI, GII, and GIV were identified, including five GI.1 strains, three GI.2 strains, one GI.3 strain, one GII.8 strain, and one GIV strain. Furthermore, multiple alignments of complete capsid protein VP1 genes of five local GI.1 strains and other available GI.1 strains in GenBank were performed. Average pairwise identities were calculated at 95.33% and 99.36% at nucleotide and amino acid levels, and only six variable amino acid sites were found during its 36-years' evolution process. GI.1 strains could be further phylogenetically divided into four clusters with an approximate temporal evolution pattern, and local strains belonged to Cluster-d with other four strains from China and Japan. In summary, SaV was identified as an etiological agent responsible for sporadic gastroenteritis in Guangzhou with a low prevalence rate as in other Chinese cities, but its high genetic diversity suggested the necessity of continuous SaV surveillance in the future.

7.
BMC Microbiol ; 19(1): 119, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31159734

RESUMO

BACKGROUND: Ready-to-eat (RTE) vegetables have become increasingly popular along with the trend of moving towards a healthy lifestyle. However, RTE vegetables are at a higher risk of containing pathogens, maybe owing to lack of rigorous sanitization procedures. To understand the prevalence and potential risk of Listeria monocytogenes in RTE vegetables, we investigated the contamination level and characteristics of L. monocytogenes isolated from fresh vegetables. RESULTS: Twenty-three (5.49%) of the 419 vegetables samples were positive for L. monocytogenes. Phylogenetic group I.1 (1/2a-3a) and II.2 (1/2b-3b-7) strains were predominant in 30 isolates, which accounted for 33.3 and 50.0%, respectively. Multilocus sequence typing of the 30 isolates grouped them into nine sequence types (STs). The most common STs were ST87 (36.7%) and ST8 (26.7%). Virulence analysis showed that all 30 isolates harbored eight classical virulence genes, 10.0% isolates harbored the llsX gene (ST3 and ST1 strains), and 36.7% carried the ptsA gene and belonged to ST87. Approximately 83.3% isolates carried full-length inlA, whereas five isolates had premature stop codons in inlA, three of which belonged to ST9 and two to ST8. Antibiotic susceptibility showed the isolates were varyingly resistant to 13 antibiotics, 26.7% of the isolates were multi-drug resistant. CONCLUSIONS: The fresh vegetables contain some potential hypervirulent L. monocytogenes (ST1 and ST87) in the Chinese markets. In addition, the high rate of L. monocytogenes isolates was multi-drug resistant. Fresh raw vegetables may be a possible transmission route for L. monocytogenes infection in consumers. Therefore, sanitization of raw fresh vegetables should be strengthened to ensure their microbiological safety when used as RTE vegetables.

8.
Infect Genet Evol ; 73: 362-367, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146046

RESUMO

Human sapovirus is regarded as an important viral agent for acute diarrhea worldwide. GII.8, a recently reported genotype, has been detected in a few countries and regions. In this study, we obtained the first genome sequence of a sapovirus GII.8 strain isolated in mainland China, and comprehensively analyzed the genetic diversity and evolutionary process of this genotype. The viral genome of the new GII.8 Guangzhou strain GZ2014-L231 comprised 7433 nucleotides, including two ORFs. Pairwise alignments of the new genome with representative sequences of different genotypes showed inconsistent homology between different protein-encoding regions, of which NS1 and VP2 were found as the variable proteins, and NS3, NS5, and NS6/7 were found as the conserved ones. Compared with other reported GII.8 genomes, the Guangzhou strain introduced 34 new nucleotide changes and one new amino acid change. Phylogenetic analysis based on full-length VP1 sequences demonstrated that 11 GII.8 strains could be divided into 4 clusters A-D, with 88 SNP and 10 SAP spots occurred during their evolutionary process. The Guangzhou strain has higher homology with seven GII.8 strain detected after 2014, especially the US and Peruvian strains of 2015/2016, which have the identical VP1 amino acid sequences. Using a Bayesian coalescent method based on VP1 sequences, GII.8 was predicted to emerge in 2001 with the evolution rate of 1.45 × 10-3 nucleotide substitutions/site/year (strict clock). In summary, the data in this study not only provided reference data from mainland China for sapovirus researches in future, but also firstly described the evolutionary process of the GII.8 genotype.

9.
Arch Virol ; 164(7): 1927-1929, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31011817

RESUMO

In the study, three Bacillus cereus-specific phages, named DK1, DK2 and DK3, belonging to the family Podoviridae, were isolated from Pearl River water and sludge in Guangzhou, China. The genomes of DK1, DK2 and DK3 were 27,180 bp, 26,357 bp, and 26,865 bp in length and contained 49, 45 and 46 open reading frames, respectively. Among the three phages, DK2 shared the highest genome sequence similarity (96% identity) with DK3. Genes encoding rRNA, tRNA, virulence factors and antibiotic resistance were absent in these phage genomes. In addition, comparative genomic and phylogenetic analysis revealed that they were novel phages of B. cereus. Each genome encoded a putative endolysin that might be of value for the control of the foodborne pathogen B. cereus.


Assuntos
Bacillus cereus/virologia , Genoma Viral/genética , Podoviridae/genética , Podoviridae/isolamento & purificação , Rios/virologia , Esgotos/virologia , China , Endopeptidases/genética , Fases de Leitura Aberta , Podoviridae/classificação
10.
Sci Rep ; 9(1): 3687, 2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30842441

RESUMO

In this study, nanoiron active carbon composites (NZVI/GAC) were used to remove chromium ions from raw water. The composites were synthesized from a novel formula of biological activated carbon and characterized by various techniques. The adsorption test data were fit by a pseudo-second-order kinetic model and Langmuir model. The qe and R2 values were 187 mg Cr/g and 0.9960, respectively, with 0.2 g/L NZVI/GAC at an initial concentration of 118 mg/L Cr according to the Langmuir isotherm model. Moreover, a Cr6+ detoxification reactor was constructed with the magnetic iron composite. The results indicated that the synthesized magnetic iron composite was a significant adsorbent for Cr6+ removal from aqueous solutions. The detoxification reactor was able to remove Cr6+ from raw water at an initial concentration of 26.5 mg/L within a short time period (3-5 min), with a removal efficiency of up to 99.90% and a treatment capacity of 45.0 mg Cr6+/g of adsorbent; the Cr6+ concentrations in the outflow met the GB5749-2006 requirements for drinking water. A synergistic effect between NZVI/GAC and a suspension of the bacterium Shewanella oneidensis MR-1 was found, showing that this bacterium can be used as a regeneration agent for iron-depleted activated carbon materials.

11.
J Phys Chem Lett ; 10(7): 1566-1573, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30840827

RESUMO

The heteronuclear metal oxide complexes are of great significance in heterogeneous catalytic oxidation of CO. However, previous studies are mainly focused on the composition of metal oxide, charge state, the support and the active oxygen species, with little attention paid to adsorbed CO ligands. Herein, the ligand-mediated reactivity in CO oxidation of niobium-nickel monoxide carbonyl complexes has been successfully identified. The NbNiO(CO) n- ( n = 5-6) anions are determined to be O-bridged complexes. In contrast, the NbNiO(CO) n- ( n = 7-8) anions are characterized to be η2-CO2-tagged complexes. The crucial roles of the multiply adsorbed CO molecules that can facilitate not only the competitive binding with bridging oxygen atom to the transition metal centers but also the electron accumulation of transition metal atoms have been discovered. The fascinating results are of substantial importance to understand the mechanisms of CO oxidation over heteronuclear metal oxide under CO-rich feed condition.

12.
Food Res Int ; 116: 994-999, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30717032

RESUMO

Cronobacter species are associated with rare but severe infections in newborns, and their tolerance to environmental stress such as acid stress has been described. However, the factors involved in low acid tolerance in Cronobacter are poorly understood. Here, a transposon mutagenesis approach was used to explore the factors involved in acid tolerance in C. malonaticus. Eight mutants from mutant library (n = 215) were successfully screened through a comparison of growth with wild type (WT) strain under acid stress (pH 4.0). Eight mutating sites including glucosyltransferase MdoH, extracellular serine protease, sulfate transporter, phosphate transporter permease subunit PstC, lysine transporter, nitrogen regulation protein NR (II), D-alanine-D-alanine ligase, glucan biosynthesis protein G were successfully identified by arbitrary polymerase chain reaction and sequencing. The biomass of biofilm of eight mutants were significantly reduced using crystal violet staining (CVS) compared with that of WT. furthermore, the more compact biofilms of WT was observed than those of eight mutants through scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Disassembly of biofilms appeared among mutants and WT strain from 48 h to 72 h through the increasing of dead cells and reduction of viable cells and exopolysaccharide. The study reveals the molecular basis involved in acid tolerance of C. malonaticus and a possible relationship between biofilm formation and acid tolerance, which provides valuable information for survival of C. malonaticus under acid stress.

13.
Infect Genet Evol ; 70: 15-23, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30776488

RESUMO

Noroviruses are the primary cause of non-bacterial acute gastroenteritis worldwide, and GII.8 belongs to a non-epidemic genotype with a limited understanding currently. In this study, we assembled the first GII.8 norovirus genome from China and clarified the temporal evolutionary process of this non-epidemic variant. Using the "4+1+1" application strategy with newly designed primer sets, the genome of one GII.8 strain GZ2017-L601 from China was firstly sequenced that comprised 7476 nucleotides. The homology of the new genome and the previous only GII.8 genome reached 93.8% identity at the nucleotide level, but only 10, 6, 7 amino acid mutations occurred in three ORFs. When compared the new strain with other GII reference strains, p22 and P2 were calculated as the variable encoding regions, and NTPase, VPg, 3CL, RdRp and S were shown as the conserved ones. We then reconstructed the evolutionary process of the GII.8 genotype using other available sequences in GenBank. Based on the partial N/C region, all GII.8 strains could be subdivided chronologically into four clusters, which spans 1967-1994, 1997-2005, 2003-2009, and 2007-2017, respectively. Moreover, differences of capsid P proteins between GII.8 strains and the epidemic GII.4 strain VA387 were also compared. There existed 147/310 distinct amino acid sites in the alignment, including two insertion and three deletion mutations. Distribution of antigen epitopes of two GII.8 variants was comparable, but the numbers of antigenic sites of GII.8 strains were less than that of VA387. In summary, the first GII.8 genome from China was assembled and extensively characterized, and a time-order evolutionary process of this genotype was identified with a static pattern of antigenic variations.

14.
J Dairy Sci ; 102(3): 2017-2021, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30638998

RESUMO

Cronobacter species are a group of opportunistic food-borne pathogens that cause rare but severe infections in neonates. Tolerance to environmental stress in Cronobacter is known; however, factors involved in oxidative stress are undefined. In this study, Cronobacter sakazakii survival, cellular morphology, and biofilm formation in response to oxidative stress were evaluated between the wild type (WT) and an outer membrane protein W (OmpW) mutant. The survival rates of ΔOmpW strain after treatment with 1.0 and 1.5 mM hydrogen peroxide were significantly reduced compared with those of WT. Morphological changes, including cell membrane damage and cell fragmentation, in ΔOmpW were more predominant than those in WT. By crystal violet staining, we also observed increased biomass in ΔOmpW biofilms as compared with WT following treatment with 0.5 and 1.0 mM H2O2. Biofilms using scanning electron microscopy and confocal laser scanning microscopy further confirmed the structural changes of biofilms between WT and ΔOmpW in response to oxidative stress. The current findings show that OmpW contributed to survival of planktonic cells under oxidative stress and the deletion of OmpW facilitated the biofilm formation in C. sakazakii to adapt to oxidative stress.


Assuntos
Proteínas da Membrana Bacteriana Externa/genética , Biofilmes/crescimento & desenvolvimento , Cronobacter sakazakii/fisiologia , Estresse Oxidativo , Proteínas da Membrana Bacteriana Externa/metabolismo , Cronobacter sakazakii/citologia , Cronobacter sakazakii/genética , Longevidade , Microscopia Confocal , Microscopia Eletrônica de Varredura
15.
Front Microbiol ; 9: 2767, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30498486

RESUMO

This study was to estimate the prevalence and characteristics of Staphylococcus aureus from 1,850 retail meat and meat products in China during July 2011 to June 2016. The samples were collected covering most provincial capitals in China, including 604 raw meat, 601 quick-frozen meat, and 645 ready-to-eat meat. Using the qualitative and quantitative methods, all 39 cities had S. aureus-positive samples, and S. aureus was detected in 35.0% (647/1,850) of the samples. The levels of S. aureus in retail meat showed that the MPN value of the majority of the positive samples ranged from 0.3 to 100 MPN/g. Twenty-four antibiotics were used to test all 868 S. aureus isolates for antibiotic susceptibility. Only 11 isolates (1.26%) were susceptible to all antibiotics, whereas most isolates (821/868, 94.6%) showed resistance or intermediary resistance to more than three or more antibiotics. Of these strains, 104 (12.0%) were resistant to more than 10 antibiotics. However, the most frequent resistance was observed to ampicillin (85.4%), followed by penicillin (84.6%), erythromycin (52.7%), tetracycline (49.3%), kanamycin (45.3%), telithromycin (30.1%), clindamycin (29.6%), streptomycin (21.1%), norfloxacin (20.4%), gentamicin (19.4%), fusidic acid (18.4%), ciprofloxacin (16.9%), chloramphenicol (13.1%), amoxycillin/clavulanic acid (11.0%), and others (<10%). 7.4% of isolates (62/868) were confirmed as methicillin-resistance S. aureus (MRSA). By molecular typing analysis, there were 164 spa types and 111 STs were identified, including 15 novel spa types and 65 newly STs by multilocus sequence typing (MLST) and spa typing. Despite the wide genetic diversity observed among the 868 isolates, a great proportion of the population belonged to finite number of major clones: ST1-t127 (93/868, 10.7%) and ST7-t091 (92/868, 10.6%), ST5-t002 (42/868, 4.8%), ST398-t034 (40/868, 4.6%), ST188-t034 (38/868, 4.4%), ST59-t437 (30/868, 3.5%), ST6-t701 (29/868, 3.3%), and ST9-t899 (27/868, 3.1%) in China. This study reflects S. aureus was readily detected in Chinese retail meat and meat products but the level were not very excessive. In this study, the high antibiotic resistance is alarming and raising public health concern. In additions, most of molecular types of isolates have been linked to human infections around the world, indicating that these types of S. aureus in China have a theoretical pathogenic potential.

16.
Crit Rev Food Sci Nutr ; : 1-24, 2018 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-30569743

RESUMO

Due to the significant growth of food production, the potential likelihood of food contamination is increasing. Foodborne illness caused by bacterial pathogens has considerably increased over the past decades, while at the same time, the species of harmful microorganisms also varied. Conventional bacterial culturing methods have been unable to satisfy the growing requirement for food safety inspections and food quality assurance. Therefore, rapid and simple detection methods are urgently needed. The loop-mediated isothermal amplification (LAMP) technology is a highly promising approach for the rapid and sensitive detection of pathogens, which allows nucleic acid amplification under isothermal conditions. The integration of the LAMP assay onto a microfluidic chip is highly compatible with point-of-care or resource-limited settings, as it offers the capability to perform experiments in combination with high screening efficiency. Here, we provide an overview of recent advances in LAMP-based microfluidic chip technology for detecting pathogens, based on real-time or endpoint determination mechanisms. We also discuss the promoting aspects of using the LAMP technique in a microfluidic platform, to supply a guideline for further molecular diagnosis and genetic analysis.

17.
Arch Virol ; 2018 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-30426215

RESUMO

A newly identified lytic Cronobacter phage, GW1, was isolated from the Pearl River of Guangzhou, China. GW1 had a double-stranded DNA genome of 39,695 nucleotides with an average GC content of 53.18 %. Among the 49 open reading frames (ORFs) identified, genes for rRNA, tRNA, antibiotic resistance, and virulence factors were not found in the phage genome. The morphology, genomic features, and phylogenetic position of GW1 revealed that it represents a new species in the genus T7virus. This novel lytic Cronobacter phage may provide an alternative for phage therapy and biocontrol against Cronobacter.

18.
J Chem Phys ; 149(14): 144305, 2018 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-30316256

RESUMO

Mass-selected heteronuclear vanadium-nickel carbonyl anions VNi(CO) n - (n = 2-6) were investigated by photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to obtain their chemical bonding and intrinsic electronic structure in the gas phase. The calculated energies (adiabatic detachment energies)/vertical detachment energies (VDEs) match well with experimental values: 1.30/1.49, 1.66/1.95, 2.22/2.48, 2.70/2.89, and 2.95/3.15 eV. The VDE value of VNi(CO) n - increases with an increase of cluster size, implying that the negative electron is stabilized upon the bonding of CO molecules. VNi(CO)2 - consists of one bridging carbonyl and one terminal carbonyl, whose feature is different from MNi(CO)2 - (M = Sc, Y, La, and Ce) with the involvement of one side-on-bonded carbonyl and one terminal CO carbonyl. The building block composed of three bridging carbonyls is favored for VNi(CO)3 -, the structure of which persists up to n = 6. The additional CO ligands are preferentially coordinated in the terminal mode to the Ni atom at n = 4 and then to the V atom at n = 5 and 6. The results obtained in this work would provide a molecular-level understanding about chemisorbed CO molecules on alloy surfaces/interfaces, which is important to understand CO molecule activation processes.

19.
Front Microbiol ; 9: 2162, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30298058

RESUMO

Phenol is a typical organic contaminant in the environment. To date, the biodegradation of phenol by microorganisms remains the preferred method for its removal and remediation, but data on phenol removal by drinking water biofilters are lacking. In this study, we used high-throughput sequencing to investigate the microbial community structure in a carbon-sand biofilter. The results indicated that the predominant bacterial group was Bacilli, followed by Gammaproteobacteria, Clostridia, and Alphaproteobacteria. In addition, a strain was capable of degrading phenol at low concentrations of 500 µg/L within 100 min was isolated and identified as Rhodococcus sp. CS-1. Transcriptome analysis results showed that Rhodococcus sp. CS-1 was able to degrade phenol via both the catechol and protocatechuate branch of the ß-ketoadipate pathway. Furthermore, some novel candidate biomarkers (copper oxidase, copper chaperone, and MarR/DeoR/TetR family transcriptional regulators) were successfully identified to be potentially involved in phenol biodegradation. This study indicates that carbon-sand filters have the potential for remediation of phenol. The application of native microorganisms to drinking water treatment system is an adaptive strategy in oligotrophic water environments.

20.
J Food Prot ; 81(11): 1761-1767, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30277802

RESUMO

Atypical enteropathogenic Escherichia coli (aEPEC) is an emerging pathogen that has been implicated in outbreaks of diarrhea worldwide. The objective of this study was to investigate the occurrence of aEPEC in retail foods at markets in the People's Republic of China and to characterize the isolates for virulence genes, intimin gene ( eae) subtypes, multilocus sequence types (STs), and antimicrobial susceptibility. From May 2014 to April 2015, 1,200 food samples were collected from retail markets in China, and 41 aEPEC isolates were detected in 2.75% (33 of 1,200) of the food samples. The virulence genes tir, katP, etpD, efa/lifA, ent, nleB, and nleE were commonly detected in these isolates. Nine eae subtypes were detected in the isolates, among which θ (23 isolates) and ß1 (6 isolates) were the most prevalent. The 41 isolates were divided into 27 STs by multilocus sequence typing. ST752 and ST10 were the most prevalent. Antibiotic susceptibility testing revealed high resistance among isolates to streptomycin (87.80%), cephalothin (73.16%), ampicillin (51.22%), tetracycline (63.42%), trimethoprim-sulfamethoxazole (43.90%), and kanamycin (43.90%). Thirty isolates (73.17%) were resistant to at least three antibiotics, and 20 (53.66 %) were resistant to five or more antibiotics. Our results suggest that retail foods in markets are important sources of aEPEC. The presence of virulent and multidrug-resistant aEPEC in retail foods poses a potential threat to consumers. Surveillance of aEPEC contamination and prudent use of antibiotics is strongly recommended in China.

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