Alina Wieliczko

Characterization of FimH Adhesins Expressed by Salmonella enterica Serovar Gallinarum Biovars Gallinarum and Pullorum: Reconstitution of Mannose-Binding Properties by Single Amino Acid Substitution

ABSTRACT Recombinant FimH adhesins of type 1 fimbriae from Salmonella enterica serovar Gallinarum biovars Gallinarum and Pullorum, in contrast to those of Salmonella enterica serovar Typhimurium, did not bind to high-mannose oligosaccharides or to human colon carcinoma HT-29 cells. However, mutated FimH proteins from biovar Gallinarum and biovar Pullorum, in which the isoleucine at position 78 was replaced by the threonine found in S. enterica serovar Typhimurium, bound well to glycoproteins carrying high-mannose oligosaccharides and colon carcinoma cells. The loss of sugar-binding properties by biovar Gallinarum and biovar Pullorum FimH adhesins, which are a part of the type 1 fimbriae, is most probably the result of a single T78I mutation, as was proven by site-directed mutagenesis of FimH proteins.

Genotypes and enterotoxin gene content of S. aureus isolates from poultry

Little is still known about the genotypes and prevalence of enterotoxin genes in animal-derived Staphylococcus aureus strains. In this study, spa type, the presence of known enterotoxin genes, and mecA gene was determined in 42 S. aureus isolates from poultry. All these isolates were classified as mecA-negative. t002, found in 19 staphylococci, was the most prevalent spa type in the studied population. t034 was found in 11 isolates. MLST performed on three t034 isolates confirmed its attachment to ST398. A strong association between the CC5 genetic background and the egc gene grouping in staphylococci of animal origin was confirmed, since all 23 isolates with t002, t214, and t010, belonging to CC5, contained egc1. No enterotoxin genes were found in 15 S. aureus isolates. In this population the most prevalent genotype was t034, found in 11 isolates. It was demonstrated that MSSA strains with the t034 ST398 genetic background also occur in poultry. This may imply, that ST398-type strains occur in a wider range of livestock species than previously believed.

Molecular Epidemiologic Investigation of Polish Avian Pasteurella multocida Strains Isolated from Fowl Cholera Outbreaks Showing Restricted Geographical and Host-Specific Distribution

SUMMARY. Molecular epidemiologic analyses of the 42 clinical isolates of Pasteurella multocida from various avian hosts (geese, ducks, turkeys, and laying hens) in Poland from 2001 to 2011, including a single reference strain, were performed by enterobacterial repetitive intergenic consensus (ERIC)-PCR, single primer PCR, and repetitive extragenic palindromic (REP)–PCR. Forty-two isolates were identified as P. multocida (serotype A). The majority of P. multocida strains were obtained from waterfowl clustered within one genotype, and they were not consistent with the genotypes obtained from the turkey strains. Pasteurella multocida showed genetic homogeneity between the host species, especially when isolated on the same farm. Some of the clones also were characteristic to the particular farm. The strains obtained in different regions represent distinct molecular patterns. The present findings demonstrate that some clones of P. multocida are restricted in geographical and host distribution. In addition, this study suggests that ERIC-PCR, single primer PCR, and REP-PCR are suitable techniques for studying the host adaptation of P. multocida and the epidemiology of fowl cholera.

In vitro characteristics of Lactobacillus spp. strains isolated from the chicken digestive tract and their role in the inhibition of Campylobacter colonization

Campylobacter jejuni/coli infections are the leading cause of bacterial diarrheal illnesses in humans. Many epidemiological studies indicate that improperly prepared meat from chickens that carry a high load of Campylobacter in their intestinal tracts is the key source of human infections. LAB, mainly members of the Lactococcus and Lactobacillus genera, increasingly have been tested as vehicles for the delivery of heterologous bacterial or viral antigens to animal mucosal immune systems. Thus, the objective of this study was to isolate, identify, and characterize Lactobacillus spp. strains isolated from chickens bred in Poland. Their ability to decrease the level of bird gut colonization by C. jejuni strain was also analyzed. First, the influence of the different chicken rearing systems was evaluated, especially the effect of diets on the Lactobacillus species that colonize the gut of chickens. Next, selected strains were analyzed in terms of their anti‐Campylobacter activity in vitro; potential probiotic traits such as adhesion properties, bile and low pH tolerance; and their ability to grow on a defined carbon source. Given that improperly prepared chicken meat is the main source of human infection by Campylobacter, the selected strains were also assessed for their ability to inhibit Campylobacter colonization in the birds intestine. These experiments revealed enormous physiological diversity among the Lactobacillus genus strains. Altogether, our results showed that L. plantarum strains isolated from the digestive tracts of chickens bred in Poland displayed some probiotic attributes in vitro and were able to decrease the level of bird gut colonization by C. jejuni strain. This suggests that they can be employed as vectors to deliver Campylobacter immunodominant proteins to the birds immune system to strengthen the efficacy of in ovo vaccination.