Prevalence and Antimicrobial Susceptibility of Enterobacteriaceae Isolated from Retail Pepper in Vietnam

A review and meta-analysis of non-typhoidal Salmonella in Vietnam: Challenges to the control and antimicrobial resistance traits of a neglected zoonotic pathogen

Non-typhoidal Salmonella (NTS) is a food-borne zoonotic pathogen with important implications for human health. Despite its importance, the burden of NTS infections in Vietnam is unknown. We conducted a systematic review and a meta-analysis to describe the prevalence and phenotypic antimicrobial resistance (AMR) for NTS over time in Vietnam. Following PRISMA guidelines, we identified 72 studies from PubMed and Google Scholar containing data relevant to 'Salmonella', 'Salmonellosis', and 'Vietnam', or 'Viet Nam'. Of those, forty-two papers reporting prevalence of NTS, and twenty-six including data on phenotypic resistance were selected for meta-analysis. The prevalence of NTS ranged from 2% to 5% in humans and from 30% to 41% in samples from animals and the farm/slaughterhouse environment. Between 2000 and 2020 we observed a 27.3% (p = 0.044) increase in absolute terms in prevalence among individuals with enteric diseases and a 12.0% (p = 0.047) increase in aquaculture/seafood samples. The most commonly serovars identified across studies included S. Weltevreden (12.0%), followed by S. Typhimurium (10.1%), S. Derby (6.4%), S. London (5.8%), S. Anatum (4.4%), S. Rissen (3.9%), S. Enteritidis (3.7%), S. Albany (3.3%) and S. 4,[5],12:i:- (3.0%). Over the same period, there was an increasing trend in the pooled AMR prevalence for quinolones (15.6% relative increase), 3rd-, 4th-, and 5th-generation cephalosporins (23.7%), penicillins (16.1%), tetracyclines (12.9%), sulfonamides (8.8%), amphenicol (17.8%), and multidrug resistance (11.4%) (all p ≤ 0.014). A broad range of AMR genes (ARGs) were detected in both human and animal populations. The observed prevalence and AMR trends in Vietnam underscore the need of adopting a One Health strategy encompassing surveillance systems, research initiatives, and awareness campaigns to effectively address the challenges posed by NTS.

Common presence of plasmid encoding blaCTX-M-55 in extended-spectrum β-lactamase-producing Salmonella enterica and Escherichia coli isolates from the same edible river fish

The transmission of potentially life-threatening plasmid-mediated antibiotic-resistant bacteria poses a major threat to public health. This study aimed to determine the presence of commonly observed plasmids encoding plasmid-mediated antibiotic-resistance genes in Salmonella and Escherichia coli isolates from fishery products. Eighty river fishes were purchased from retail stores and supermarkets in Vietnam. Only Salmonella-positive fishes were used for antibiotic-resistant E. coli isolation. Salmonella serotyping was performed using Salmonella antisera. Isolated bacterial DNA was extracted, and antibiotic susceptibility, resistance genes, and replicon typing were determined. Our results showed that Salmonella was isolated from 12.5% (10/80) of the river fishes. Cefotaxime-resistant Salmonella was isolated from 3.8% (3/80) of the fishes and colistin-resistant Salmonella from 1.3% (1/80) . Salmonella serotyping revealed Potsdam, Schwarzengrund, Bardo/Newport, Give, Infantis, Kentucky, and Typhimurium. Multiplex polymerase chain reaction revealed the presence of extended-spectrum β-lactamase-related genes blaCTX-M-55 and blaCTX-M-65 and the colistin resistance gene mcr-1. To date, no study has reported an antibiotic-resistance plasmid present in multiple bacteria collected from the same food. Thus, horizontal transmission of antibiotic-resistance plasmids may occur at the food level.

A systematic review and meta-analysis of integrated studies on antimicrobial resistance in Vietnam, with a focus on Enterobacteriaceae, from a One Health perspective

Vietnam is a low- and middle-income country (LMIC), a primary food producer, and an antimicrobial resistance (AMR) hotspot. AMR is recognized as a One Health challenge since it may transfer between humans, animals and the environment. This study aimed to apply systematic review and meta-analysis to investigate the phenotypic profiles and correlations of antimicrobial-resistant Enterobacteriaceae across three compartments: humans, animals and the environment in Vietnam. A total of 89 articles found in PubMed, Science Direct, and Google Scholar databases were retrieved for qualitative synthesis. E. coli and non-typhoidal Salmonella (NTS) were the most common bacterial species in studies of all compartments (60/89 studies). Among antimicrobials classified as critically important, the resistance levels were observed to be highest to quinolones, 3rd generation of cephalosporins, penicillins, and aminoglycosides. Of 89 studies, 55 articles reported the resistance prevalence of E. coli and NTS in healthy humans, animals and the environment against ciprofloxacin, ceftazidime, ampicillin, gentamicin, sulfamethoxazole-trimethoprim, chloramphenicol was used for meta-analysis. The pooled prevalence was found highest in E. coli against ampicillin 84.0% (95% CI 73.0-91.0%) and sulfamethoxazole-trimethoprim 66.0% (95% CI 56.0-75.0%) while in NTS they were 34.0% (95% CI 24.0-46.0%), 33.0% (95% CI 25.0-42.0%), respectively. There were no significant differences in the pooled prevalence of E. coli and NTS to these antimicrobials across healthy humans, animals and the environment, except for ceftazidime-resistant E. coli (χ² = 8.29, p = 0.02), chloramphenicol-resistant E.coli (χ² = 9.65, p < 0.01) and chloramphenicol-resistant NTS (χ² = 7.51, p = 0.02). Findings from the multiple meta-regression models indicated that the AMR levels in E. coli (β = 1.887, p < 0.001) and the North (β = 0.798, p = 0.047) had a higher fraction of AMR than NTS and other regions of Vietnam. The outcomes of this study play an important role as the baseline information for further investigation and follow-up intervention strategies to tackle AMR in Vietnam, and more generally, can be adapted to other LMICs.

Frequent contamination of edible freshwater fish with colistin-resistant Escherichia coli harbouring the plasmid-mediated mcr-1 gene

The threat of antimicrobial resistance is increasing. Microbial food contamination poses a serious public health risk; however, there are only a few studies on the prevalence of colistin-resistant Escherichia coli (COL-E) contamination in freshwater fish. This study aimed to characterise the antibiotic resistance genes and antibiotic susceptibility profiles of COL-E in freshwater fish in Vietnam. In total, 103 fish were collected and 63 COL-E were isolated. COL-E was investigated by genotyping mcr and AmpC/extended-spectrum β-lactamase (ESBL)-related genes. The results show that COL-E and AmpC/ESBL-producing COL-E were confirmed in 24.3 % and 14.6 % of the fish, respectively. Multiplex PCR for mcr-1-9 showed that all 63 COL-E harboured mcr-1, while mcr-3 was detected in 7.9 % of COL-E. The minimum inhibitory concentration of colistin ranged from 2 to 256 μg/mL. Meanwhile, antibiotic susceptibility results show that all COL-E were resistant to ampicillin, streptomycin, and chloramphenicol.

Abundance of colistin-resistant Escherichia coli harbouring mcr-1 and extended-spectrum β-lactamase-producing E. coli co-harbouring blaCTX-M-55 or -65 with blaTEM isolates from chicken meat in Vietnam

Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic bla_CTX-M in extended-spectrum β-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were bla_CTX-M-55 and bla_CTX-M-65 together with bla_TEM in Vietnamese chickens and bla_CMY-2 in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant bla_CTX-M in ESBL-producing E. coli was bla_CTX-M-55 or bla_CTX-M-65, with the coexistence of bla_TEM in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance.

Untargeted Phylogenetic Group III of Multi-drug-Resistant Bacillus cereus Isolated Using Fraser Medium from Retail Chickens in Ho Chi Minh City

The prevalence of food-borne bacteria in developing countries is less well understood than in developed countries. The ISO11290-1 isolation method is commonly used to study Listeria contamination in chicken; however, all isolates are identified as untargeted Bacillus cereus. This study aimed to determine the classification, antibiotic susceptibility, and virulence genes of B. cereus isolated from retail chickens in Vietnam. Bacterial isolation using the ISO11290-1 method yielded 12 strains of B. cereus from seven out of 60 chickens. For determining bacterial diversity, panC and multilocus sequence typing (MLST) analyses were performed. PanC analysis showed that all seven strains belong to the phylogenetic group III, to which the highest risk of foodborne illnesses was associated. MLST analysis showed that most strains contained a ST205 complex; further, all strains were found to be resistant to ampicillin, ciprofloxacin, and tetracycline. Virulence genes were also investigated. ces, a cereulide-related gene, was detected in 50% of the isolated strains, followed by cytK, nheA, and hblA enterotoxins in 41.7%, 16.7%, and 25% of the strains, respectively. In conclusion, B. cereus may be erroneously detected when attempting to detect Listeria in food using the ISO11290-1 method. Further study of the prevalence of B. cereus in Vietnamese food is needed to improve food safety.

Antibacterial Use of Macroalgae Compounds against Foodborne Pathogens

The search for food resources is a constant in human history. Nowadays, the search for natural and safe food supplies is of foremost importance. Accordingly, there is a renewed interest in eco-friendly and natural products for substitution of synthetic additives. In addition, microbial contamination of food products during their obtaining and distribution processes is still a sanitary issue, and an important target for the food industry is to avoid food contamination and its related foodborne illnesses. These diseases are fundamentally caused by certain microorganisms listed in this review and classified according to their Gram negative or positive character. Algae have proven to possess high nutritional value and a wide variety of biological properties due to their content in active compounds. Among these capabilities, macroalgae are recognized for having antimicrobial properties. Thus, the present paper revises the actual knowledge of microbial contaminants in the food industry and proposes antimicrobial algal compounds against those pathogenic bacteria responsible for food contamination as valuable molecules for its growth inhibition. The capacity of algae extracts to inhibit some major food pathogen growth was assessed. Moreover, the main applications of these compounds in the food industry were discussed while considering their favorable effects in terms of food safety and quality control.

Prevalence Of mcr-1 Among Cefotaxime-Resistant Commensal Escherichia coli In Residents Of Vietnam

Purpose

The dissemination of colistin-resistant bacteria harboring the colistin-resistance gene mcr-1 in developing countries has recently entered the spotlight as an emerging public health threat, which is attributed to the abuse of colistin use in these countries. However, the prevalence of these bacteria in developing countries has not been extensively investigated. Therefore, in the present study, we examined the prevalence of cefotaxime-resistant commensal Escherichia coli harboring mcr-1 among residents of a representative Vietnamese village and assessed the characteristics of these isolates.

Materials and methods

The stool samples, one stool sample per resident, of 612 residents were cultured on MacConkey agar with cefotaxime. Resulting E. coli-like colonies were isolated and examined further for the presence of colistin-resistant extended-spectrum β-lactamase (ESBL)-producing E. coli with mcr-1. Antibiotic susceptibility tests were performed, and clonal relationship among colistin-resistant isolates was assessed.

Results

Thirty-one of the 451 cefotaxime-resistant E. coli isolates were resistant to colistin and the majority possessed mcr-1, bla_CTX-M, and/or bla_TEM, except for two isolates that produced the AmpC β-lactamase. All mcr-1 ESBL-producing E. coli isolates were multidrug-resistant (5–11 antibiotics). The isolates contained various plasmid replicon types, including the most prevalent types IncHI2 (54.8%), IncFIB (48.4%), and IncN (41.9%). In addition, 83.9% of the mcr-1 ESBL-E. coli isolates possessed a transposon ISApl1-mcr-1 segment. Furthermore, 77.4% of the mcr-1 ESBL-E. coli isolates belonged to phylogenetic group A. Pulsed-field gel electrophoresis analysis indicated limited clonal expansion of a specific strain.

Conclusion

These results demonstrate the wide dissemination of colistin-resistant ESBL-E. coli harboring mcr-1 among commensal bacteria of rural residents in Vietnam, suggesting possible mobilization of the mcr-1 gene among ESBL-producing microbiota, which is a great public health concern.

The presence of colistin resistance gene mcr-1 and -3 in ESBL producing Escherichia coli isolated from food in Ho Chi Minh City, Vietnam

Colistin is indicated for the treatment of multidrug-resistant gram-negative bacterial infections. However, the spread of colistin-resistant bacteria harbouring an mcr gene has become a serious concern. This study investigated local foods in Vietnam for contamination with colistin-resistant bacteria. A total of 261 extended-spectrum β-lactamase (ESBL)- and AmpC-producing Escherichia coli isolates from 330 meat and seafood products were analysed for colistin susceptibility and the presence of mcr genes. Approximately, 24% (62/261) of ESBL- or AmpC-producing E. coli isolates showed colistin resistance; 97% (60/62) of colistin-resistant isolates harboured mcr-1, whereas 3% (2/62) harboured mcr-3. As the result of plasmid analysis of two strains, both plasmids harbouring mcr-3 revealed that plasmid replicon type was IncFII. Sequencing analysis indicated that an insertion sequence was present near mcr-3, suggesting that IncFII plasmids harbouring mcr-3 could be transferred to other bacterial species by horizontal transfer of the plasmid or transfer with some insertion sequence. In conclusion, ESBL-producing E. coli and AmpC-producing E. coli have acquired colistin resistance because 24% of such isolates show colistin resistance and 3% of the colistin-resistant strains harbour mcr-3. We reported the present of the mcr-3-carrying ESBL-producing E. coli isolated from pork in Vietnam.

Prevalence and Antimicrobial Susceptibility of Bacterial Pathogens in Ready-to-Eat Foods Retailed in Osaka Prefecture, Japan

The potential human health risk of Japanese ready-to-eat (RTE) foods was investigated by determining the contamination by foodborne bacterial pathogens, the prevalence of opportunistic and nosocomial pathogens, and the antibiotic susceptibility of the isolates recovered from 96 samples of lightly pickled vegetables, 88 samples of Western-style desserts, and 98 samples of RTE fish and seafood products sold at retail in Osaka, Japan. Staphylococcus aureus, including isolates producing staphylococcal enterotoxin (SE), were isolated from six lightly pickled vegetable products, seven Western-style dessert products, and three RTE fish and seafood products. Of these isolates, one SEC-producing isolate from a cake was identified as community-acquired methicillin-resistant S. aureus, which was multilocus sequence type 8 and staphylococcal cassette chromosome mec type IV. Enterobacteriaceae species, including Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens, Citrobacter freundii-Citrobacter braakii, and/or the Enterobacter cloacae complex, were isolated from 92 (95.8%) of the lightly pickled vegetable products, 39 (44.3%) of the Western-style dessert products, and 74 (75.5%) of the RTE fish and seafood products. On the basis of the antimicrobial susceptibility profiles of the opportunistic and nosocomial Enterobacteriaceae pathogens, the third-generation cephalosporin, fosfomycin, and quinolone resistance determinants were investigated. We detected AmpC products of the CIT group and a qnrB9 product in 5 and 1 C. freundii-C. braakii isolates, respectively, and fosA gene products in 15 E. cloacae complex isolates. Because RTE foods are consumed without a heating process, the spread of bacterial pathogens from contaminated food to human consumers is possible. RTE foods must be handled using hygienic procedures from the processing steps to the table to reduce the prevalence of potentially pathogenic or pathogenic bacteria and to prevent bacterial growth.