The presence of Salmonella in hatchlings is the single most important risk factor for the introduction of Salmonella into poultry farms, and resistant strains are particularly worrisome, as they ...could affect treatment outcomes in humans infected through consumption of contaminated poultry products. This study estimated Salmonella prevalence, determined resistance profiles of strains recovered from hatchlings in Nigeria, and determined genetic relatedness between hatchling strains and strains from poultry farms. In this study, 300 fecal samples were collected. Salmonella was isolated by culture and confirmed by PCR, and isolates were tested for susceptibility to antimicrobials by the disk diffusion method. Strains were pair-end sequenced, and genomes were used to obtain serotypes and antibiotic resistance genes. Whole-genome based phylogenetic analysis was used to determine genetic relatedness between these isolates and strains from previously characterized older chicken within the same geographical area. A prevalence of 10.7% was obtained belonging to 13 Salmonella serovars. Resistance to kanamycin (30/32), ciprofloxacin (22/32), nalidixic acid (22/32), and sulfonamides (22/32) were the most commonly observed phenotypic resistances. Twenty-two (68.8%) isolates showed multidrug resistance. In silico predictions identified 36 antimicrobial resistance genes. Four (12.5%) and 22 (68.8%) strains showed point mutations in gyrA and parC. Commonly observed acquired resistance genes included sul1, sul2, sul3, and tet(A) as well as a variety of aminoglycoside-modifying genes. Eleven (34.4%) isolates were predicted to have genes that confer resistance to fosfomycin (fosA7, fosB). A strain of S. Stanleyville was predicted to have optrA, which confers resistance to furazolidone. Strains of S. Kentucky, S. Muenster, and S. Menston obtained from hatchlings showed close genetic relatedness by having less than 30 SNPs difference to strains recovered from chickens at farms previously receiving hatchlings from the same sources.
During 2010-2018 in Denmark, 638 patients had Vibrio infections diagnosed and 521 patients had Shewanella infections diagnosed. Most cases occurred in years with high seawater temperatures. The ...substantial increase in those infections, with some causing septicemia, calls for clinical awareness and mandatory notification policies.
Culture of tilapia (Oreochromis spp.) and whiteleg shrimp (Litopenaeus vannamei) has intensified during the last decade in China with increased production, meanwhile it has also brought some ...problems, including diseases, increased use of antimicrobials and other chemicals for disease control and pond water quality management. This study investigated the knowledge, practices and challenges of tilapia and whiteleg shrimp farmers when preventing and controlling diseases through the use of antimicrobials and other compounds in Guangdong province, which is the most important shrimp and tilapia production area in China. Tilapia farmers (25) mainly reported streptococcosis (9) and exophthalmia disease (9) which often was treated with sulfadiazine, florfenicol and vitamins or rhubarb (Rheum rhabarbarum) extract, although farmers thought the effectiveness of antimicrobial treatment has decreased in recent years. Shrimp farms (30) mainly experienced outbreaks of red body disease (19) and white spot syndrome (5), both viral diseases, and so-called “secret death disease” (5) which farmers controlled by application of a variety of disinfectants, probiotics and vitamins. Most of the farmers reported they did not use antimicrobials to treat shrimp disease. All farmers applied disinfectants and probiotics to control pond water quality although the efficacy of such use was not known. Farmers prepared their own medicated feed through mixing antimicrobial water-based solutions into the feed pellets with bare hands with small and medium scale farmers having little awareness of associated occupational health hazards. This practice together with inferior drug quality will lead farmers to administer sub-therapeutic antimicrobial concentrations with the subsequent risks of treatment failure and resistance development. Farmers stated lower costs and stricter regulation on antimicrobial usage as reasons for the popularity of probiotics. Farmers also reported the use of herbal extracts for disease control and water quality improvements, partly because of the low number of reported negative side effects and no antimicrobial residue problems. Local chemical supply shops, with representatives often visiting the farms, were important sources of information that farmers used when diagnosing and treating diseases. Farmers also relied on their own experience and current practices of chemical use do not seem cost-effective. Thus, government, academia, and the private sector should cooperate, e.g. in private–public partnerships, to improve advisory services and offer training to farmers, in particular on prudent and efficient use of antimicrobials and other compounds. Approval procedures and legislation of products used in aquaculture should be strengthened and enforced ensuring farmers' access to quality and efficient agents for disease control.
This study reports the knowledge, practices and challenges of tilapia and white leg shrimp farmers in China when preventing and controlling diseases through the use of antimicrobials and other compounds. Farmers lack sufficient knowledge and access to advisory services to prudently use antimicrobials and other compounds in aquaculture. Innovative private–public partnerships may provide such services.
•We investigated 25 tilapia farms and 30 whiteleg shrimp farms in China and acquired farmers’ knowledge and practices about disease control.•Farmers from most small and medium farms are inadequate to control diseases by using antimicrobials and other chemicals.•The way to mix and apply medicated feed by farmers may lead to treatment failures and occupational health risks.•Innovative efforts, e.g. in private-public partnerships, are needed to improve advisory services and offer training to farmers.
Staphylococcus aureus is an opportunistic pathogen leading to food poisoning as well as human infections. The present study examined the prevalence and characterization of antimicrobial-resistant S. ...aureus in sushi from 42 outlets and in pork products from eight outlets in Beijing, China. The total bacterial counts were between 3.0 and 8.9 log CFU/g (mean 5.5 ± 1.5 log CFU/g) in sushi products and 4.8 to 7.4 log CFU/g (mean 5.6 ± 0.8 log CFU/g) in pork products. The mean counts of coliforms were 2.7 and 2.9 log CFU/g in sushi and pork, respectively. Staphylococcus aureus was isolated from seven sushi outlets (13 isolates) and two pork outlets (2 isolates) with average counts below 2 log CFU/g in all cases. A total of 15 S. aureus isolates were further characterized. Six lineages of S. aureus were present, including ST398 (n = 5), ST25 (n = 4), ST15 (n = 2), ST59 (n = 2), ST8 (n = 1) and ST2631 (n = 1). Thirteen isolates contained the scn virulence marker, whereas four and eight isolates contained the virulence marker edinB and enterotoxin genes, respectively. Characterization of antimicrobial resistance profiles documented resistances to ampicillin (n = 15), penicillin (n = 14), ceftazidime (n = 6), erythromycin (n = 4), tetracycline (n = 3), clindamycin (n = 3), and gentamicin (n = 1). Three MRSA isolates were obtained, one from pork (ST398) and two from one sushi outlet (ST59). They were all resistant to at least three classes of antimicrobials and two of them contained the scn gene and enterotoxin genes. Twelve sushi isolates and one of the pork isolates contained the scn gene, indicating that they were of human origin. This emphasizes the potential importance of transmission through foods of antimicrobial-resistant S. aureus including MRSA. We also showed that S. aureus exhibited geographical variation with regards to ST profiles, antimicrobial-resistance and virulence genes when comparing isolates from sushi products sold in Beijing and Copenhagen, Denmark. Whereas food safety is not compromised by the presence of low amounts of S. aureus in sushi, this study shows that with regards to public health such foods may serve as vehicles for transmission of multidrug-resistant S. aureus and MRSA lineages.
•The aerobic mesophilic counts were 5.5 ± 1.5 log CFU/g for sushi products and 5.6 ± 0.8 log CFU/g for pork products.•Three MRSA strains were resistant to at least three classes of antimicrobials and thus designated as multidrug-resistant.•Six lineages of S. aureus were detected: ST398 (n = 5), ST25 (n = 4), ST15 (n = 2), ST59 (n = 2), ST8 (n = 1) and ST2631 (n = 1).•The MRSA isolates contained scn and enterotoxin genes.
Salmonella is an important human pathogen and poultry products constitute an important source of human infections. This study investigated prevalence; identified serotypes based on whole genome ...sequence, described spatial distribution of Salmonella serotypes and predicted risk factors that could influence the prevalence of Salmonella infection in commercial poultry farms in Nigeria. A cross sectional approach was employed to collect 558 pooled shoe socks and dust samples from 165 commercial poultry farms in North West Nigeria. On-farm visitation questionnaires were administered to obtain information on farm management practices in order to assess risk factors for Salmonella prevalence. Salmonella was identified by culture, biotyping, serology and polymerase chain reaction (PCR). PCR confirmed isolates were paired-end Illumina- sequenced. Following de novo genome assembly, draft genomes were used to obtain serotypes by SeqSero2 and SISTR pipeline and sequence types by SISTR and Enterobase. Risk factor analysis was performed using the logit model. A farm prevalence of 47.9% (CI95 40.3-55.5) for Salmonella was observed, with a sample level prevalence of 15.9% (CI95 12.9-18.9). Twenty-three different serotypes were identified, with S. Kentucky and S. Isangi as the most prevalent (32.9% and 11%). Serotypes showed some geographic variation. Salmonella detection was strongly associated with disposal of poultry waste and with presence of other livestock on the farm. Salmonella was commonly detected on commercial poultry farms in North West Nigeria and S. Kentucky was found to be ubiquitous in the farms.
Antimicrobial resistance (AMR) is a global health threat affecting treatment outcome in animals and humans. A pre-requisite for development of AMR reduction strategies is knowledge of antimicrobial ...use patterns, and how these affect resistance development. The aim of this study was to determine antimicrobial usage (AMU) and whether such usage was associated with AMR in Salmonella from poultry farms in Northwest Nigeria.
Fifteen (37%) of antimicrobial products observed contained compounds that are of highest priority and critically important for human medicine. Broilers chicken consumed higher (28 ± 14 mg/kg active ingredients) amounts of antimicrobials compared to layers (13 ± 8 mg/kg) per week (p = 0.0009). Surprisingly, chickens raised under backyard system consumed higher amounts of antimicrobials (34 ± 7 mg/kg) than poultry in other systems (p = 0.02). High levels of resistance to tetracycline (58%), sulphonamides (65%), ciprofloxacin (46%) and gentamicin (42%) correlated with high farm level usage of these antimicrobials, and there was a strong correlation (r = 0.9) between farm usage and resistance of isolates to the same antimicrobials (p = 0.03).
High AMU, including use of highest priority critically important antimicrobials was observed at poultry farms in Northwest Nigeria. AMU correlated with high levels of resistance. Communication of prudent use of antimicrobials to farmers and regulation to obtain reduction in AMU should be a priority.
Ancylostoma ceylanicum, a hookworm of canids and felids in Asia, is becoming the second most common hookworm infecting humans. In 2012, we investigated the prevalence and infection dynamics of and ...risk factors for hookworm infections in humans and dogs in a rural Cambodian village. Over 57% of the population was infected with hookworms; of those, 52% harbored A. ceylanicum hookworms. The greatest intensities of A. ceylanicum eggs were in persons 21-30 years of age. Over 90% of dogs also harbored A. ceylanicum hookworms. Characterization of the cytochrome oxidase-1 gene divided isolates of A. ceylanicum hookworms into 2 groups, 1 containing isolates from humans only and the other a mix of isolates from humans and animals. We hypothesize that preventative chemotherapy in the absence of concurrent hygiene and animal health programs may be a factor leading to emergence of A. ceylanicum infections; thus, we advocate for a One Health approach to control this zoonosis.
Nisin is applied as a food preservative in processed foods and has the potential to be used synergistically with antibiotics for treatment of patients infected by antibiotic-resistant bacteria, such ...as methicillin-resistant Staphylococcus aureus. The present study explores the antimicrobial effect of nisin on S. aureus viability and membrane integrity and, for the first time, used super-resolution microscopy to study morphological changes induced in S. aureus cells exposed to nisin. The exposure of S. aureus to nisin caused membrane depolarization and rapid killing. Super-resolution structured-illumination microscopy and transmission electron microscopy confirmed that nisin damages the cellular membrane and causes lysis of cells. Strikingly, condensation of chromosomal DNA was observed in all cells exposed to nisin, a phenotype not previously reported for this compound. Moreover, cells exposed to nisin were significantly smaller than non-exposed cells indicating the emergence of cell shrinkage. The strong association of DNA condensation with nisin exposure indicates that nisin interferes with chromosome replication or segregation in S. aureus.Nisin is applied as a food preservative in processed foods and has the potential to be used synergistically with antibiotics for treatment of patients infected by antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus. The present study explores the antimicrobial effect of nisin on S. aureus viability and membrane integrity and, for the first time, used super-resolution microscopy to study morphological changes induced in S. aureus cells exposed to nisin. The exposure of S. aureus to nisin caused membrane depolarization and rapid killing. Super-resolution structured-illumination microscopy and transmission electron microscopy confirmed that nisin damages the cellular membrane and causes lysis of cells. Strikingly, condensation of chromosomal DNA was observed in all cells exposed to nisin, a phenotype not previously reported for this compound. Moreover, cells exposed to nisin were significantly smaller than non-exposed cells indicating the emergence of cell shrinkage. The strong association of DNA condensation with nisin exposure indicates that nisin interferes with chromosome replication or segregation in S. aureus.
Non-enterica subspecies of Salmonella enterica are rarely associated with human infections. Paradoxically, food safety legislations consider the entire genus Salmonella as pathogenic to humans. ...Globally, large amounts of seafoods are rejected and wasted due to findings of Salmonella. To inform better food safety decisions, we investigated the pathogenicity of Salmonella Salamae 42:r- and Salmonella Waycross isolated from Nile perch from Lake Victoria. Genome-wide analysis revealed absence of significant virulence determinants including on key Salmonella pathogenicity islands in both serovars. In epithelial cells, S. Salamae showed a weak invasion ability that was lower than the invH mutant of S. Typhimiurium used as negative control. Similarly, S. Salamae could not replicate inside macrophages. Moreover, intracellular replication in S. Waycross strains was significantly lower compared to the wild type S. Typhimurium. Our findings suggest a low pathogenicity of S. Salamae reinforcing the existing literature that non-enterica subspecies are avirulent. We propose that food legislations and actions taken on findings of Salmonella are revisited to avoid wasting valuable sea- and other foods.
Vibrio cholerae remains a major public health threat worldwide, causing millions of cholera cases each year. Although much is known about the evolution and pathogenicity of the O1/O139 serogroups of ...V. cholerae, information is lacking on the molecular epidemiology of non‒O1/O139 strains isolated from patients who have diarrheal illnesses. We performed whole-genome sequence analysis and in vivo infections to investigate characteristics of V. cholerae O141 isolated from sporadic diarrheal cases in 4 countries. The strains formed a distinct phylogenetic clade distinguishable from other serogroups and a unique multilocus sequence type 42, but interstrain variation suggests that O141 isolates are not clonal. These isolates encode virulence factors including cholera toxin and the toxin-coregulated pilus, as well as a type 3 secretion system. They had widely variable capacities for intestinal colonization in the infant mouse model. We propose that O141 isolates comprise a distinct clade of V. cholerae non‒O1/O139, and their continued surveillance is warranted.
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