Chemotactic behavior of Campylobacter spp. in function of different temperatures (37 °C and 42 °C)

Multi-virulence of Campylobacter jejuni carried by chicken meat in Brazil

Campylobacter jejuni is the most frequent cause of bacterial gastroenteritis; therefore, the characteristics of its epidemiology must be continuously investigated to support possible mitigating measures. This is particularly important when evaluating representative strains from the world's leading chicken meat exporter, Brazil. We evaluated a panel of 14 virulence genes in 359 strains of C. jejuni isolated from chilled broiler carcasses in Brazil. The genes were classified into five virulence categories (B: biofilm/motility; SS: secretion/cytotoxicity system; CI: invasion/colonization; GB: Guillain-Barré; and AE: adaptation to stress). The percentage of strains with stress adaptation genes (86.07%) indicates the ability to survive in unfavorable environments; in addition, the strains showed a risk of causing infections in humans due to the frequency of the hcp gene (97.77%). Genes related to Guillain-Barre syndrome (GBS) in 77.44% of strains are an additional concern, which must be monitored. The gene panel showed the presence of 124 virulence profiles. Individual analyses by carcass, slaughter establishment, and municipalities in which they were located showed high index variabilities (I.Var.) of 0.82, 0.87, and 0.78, respectively. Georeferencing indicated the state of Paraná as a hotspot for virulent strains. Higher levels of isolation and multi-virulence were identified in the summer, which is hot and humid in Brazil. Together, our results showed that the studied strains are a potential danger to public health and that there is an urgent need for their surveillance and the adoption of control measures, especially in the state of Paraná.

Characterisation of Campylobacter spp. Isolated from Poultry in KwaZulu-Natal, South Africa

This study investigated the antibiotic resistance, virulence profiles, and clonality of Campylobacter jejuni and Campylobacter coli isolated from an intensive poultry farming system in KwaZulu-Natal, South Africa. Following ethical approval, samples were collected over six weeks using the farm-to-fork approach. Campylobacter spp. were identified using culture, confirmed and differentiated to species level by PCR, and subjected to antibiotic susceptibility testing. Selected antibiotic resistance (and mutations) and virulence genes were screened by PCR and confirmed by DNA sequencing. Genetic relatedness amongst the isolates was ascertained using pulsed-field gel electrophoresis. In all, 105 isolates were confirmed as belonging to both Campylobactercoli (60; 57%) and C. jejuni (45; 43%). The highest resistance was recorded against erythromycin and clindamycin. The gyrA mutation, A20175C/A2074G point mutation, tet(O), and cmeB, all associated with antibiotic resistance, were detected. All the virulence genes (pldA, ciaB, cdtA, cdtB, cdtC, dnaJ, except for cadF) were also detected. Isolates were grouped into five pulsotypes displaying 85% similarity, irrespective of their resistance profiles. The numerous permutations of clonality, antibiotic resistance, and virulence profiles evident in Campylobacter spp. pose a challenge to food safety and necessitate a comprehensive understanding of the molecular epidemiology of this organism to decrease its spread in the food chain.

L-fucose influences chemotaxis and biofilm formation in Campylobacter jejuni

Campylobacter jejuni and Campylobacter coli are zoonotic pathogens once considered asaccharolytic, but are now known to encode pathways for glucose and fucose uptake/metabolism. For C. jejuni, strains with the fuc locus possess a competitive advantage in animal colonization models. We demonstrate that this locus is present in > 50% of genome-sequenced strains and is prevalent in livestock-associated isolates of both species. To better understand how these campylobacters sense nutrient availability, we examined biofilm formation and chemotaxis to fucose. C. jejuni NCTC11168 forms less biofilms in the presence of fucose, although its fucose permease mutant (fucP) shows no change. In a newly developed chemotaxis assay, both wild-type and the fucP mutant are chemotactic towards fucose. C. jejuni 81-176 naturally lacks the fuc locus and is unable to swim towards fucose. Transfer of the NCTC11168 locus into 81-176 activated fucose uptake and chemotaxis. Fucose chemotaxis also correlated with possession of the pathway for C. jejuni RM1221 (fuc+) and 81116 (fuc-). Systematic mutation of the NCTC11168 locus revealed that Cj0485 is necessary for fucose metabolism and chemotaxis. This study suggests that components for fucose chemotaxis are encoded within the fuc locus, but downstream signals only in fuc + strains, are involved in coordinating fucose availability with biofilm development.

Thermotolerant Campylobacter during Broiler Rearing: Risk Factors and Intervention

Thermotolerant Campylobacters are one of the most important bacterial causative agents of human gastrointestinal illness worldwide. In most European Union (EU) member states human campylobacteriosis is mainly caused by infection with Campylobacter jejuni or Campylobacter coli following consumption or inadequate handling of Campylobacter-contaminated poultry meat. To date, no effective strategy to control Campylobacter colonization of broilers during rearing is available. In this review, we describe the public health problem posed by Campylobacter presence in broilers and list and critically review all currently known measures that have been researched to lower the numbers of Campylobacter bacteria in broilers during rearing. We also discuss the most promising measures and which measures should be investigated further. We end this review by elaborating on readily usable measures to lower Campylobacter introduction and Campylobacter numbers in a broiler flock.

Utilization of host-derived cysteine-containing peptides overcomes the restricted sulphur metabolism of Campylobacter jejuni

The non-glycolytic food-borne pathogen Campylobacter jejuni successfully colonizes the intestine of various hosts in spite of its restricted metabolic properties. While several amino acids are known to be used by C. jejuni as energy sources, none of these have been found to be essential for growth. Here we demonstrated through phenotype microarray analysis that cysteine utilization increases the metabolic activity of C. jejuni. Furthermore, cysteine was crucial for its growth as C. jejuni was unable to synthesize it from sulphate or methionine. Our study showed that C. jejuni compensates this limited anabolic capacity by utilizing sulphide, thiosulphate, glutathione and the dipeptides γGlu-Cys, Cys-Gly and Gly-Cys as sulphur sources and cysteine precursors. A panel of C. jejuni mutants in putative peptidases and peptide transporters were generated and tested for their participation in the catabolism of the cysteine-containing peptides, and the predicted transporter protein CJJ81176_0236 was discovered to facilitate the growth with the dipeptide Cys-Gly, Ile-Arg and Ile-Trp. It was named Campylobacter peptide transporter A (CptA) and is the first representative of the oligopeptide transporter OPT family demonstrated to participate in the glutathione-derivative Cys-Gly catabolism in prokaryotes. Our study provides new insights into how host- and microbiota-derived substrates like sulphide, thiosulphate and short peptides are used by C. jejuni to compensate its restricted metabolic capacities.

How a sugary bug gets through the day: recent developments in understanding fundamental processes impacting Campylobacter jejuni pathogenesis

Campylobacter jejuni is a highly prevalent yet fastidious bacterial pathogen that poses a significant health burden worldwide. Lacking many hallmark virulence factors, it is becoming increasingly clear that C. jejuni pathogenesis involves different strategies compared with other well-characterized enteric organisms. This includes the involvement of basic biological processes and cell envelope glycans in a number of aspects related to pathogenesis. The past few years have seen significant progress in the understanding of these pathways and how they relate to C. jejuni fundamental biology, stress survival, colonization, and virulence attributes. This review focuses on recent studies in three general areas where "pathogenesis" and "basic biology" overlap: physiology, stress responses and glycobiology.