Campylobacter-associated gastroenteritis remains an important cause of morbidity worldwide, and some evidence suggests that poultry is an important source of this foodborne infection in humans. This study was conducted to analyze the prevalence and genetic background of resistance of 149 Campylobacter jejuni and 54 Campylobacter coli strains isolated from broiler chicken carcasses and from stool samples of infected children in Poland from 2003 through 2005. Nearly all isolates were susceptible to macrolides and aminoglycosides. The highest resistance in both human and chicken strains was observed for ciprofloxacin (more than 40%), followed by ampicillin (13 to 21%), and tetracycline (8 to 29%). Resistance to ampicillin and tetracycline rose significantly between 2003 and 2005. Slight differences in resistance between human and chicken isolates indicate that although chicken meat is not the only source of Campylobacter infection in our population, it can be involved in the transmission of drug-resistant Campylobacter strains to humans.

The genetic similarity of non-toxigenic C. diphtheriae strains causing infection suggests that the strains represent a single clone. They may possess additional virulence genes in a chromosome, related with higher pathogenicity and invasiveness. The genetic changes have not been followed by resistance to antibiotics.

A Klebsiella pneumoniae epidemic strain that coproduced carbapenemase KPC-2 (K. pneumoniae carbapenemase 2) and 16S rRNA methylase ArmA has emerged in Poland. Four nonduplicate isolates from patients in a hospital in Warsaw, Poland, were found to carry the bla KPC-2 and armA genes on ca. 50-kb and 90-kb plasmids, respectively. Tn4401 with a 100-bp deletion in the variable region was detected in all the isolates. XbaI pulsed-field gel electrophoresis (PFGE) revealed 93.2% similarity of the isolates. All the isolates were resistant to carbapenems and 4,6-disubstituted 2-deoxystreptamines.

We tested 102 Campylobacter jejuni and 6 Campylobacter coli clinical isolates from Poland. All were susceptible to erythromycin. Among the tested C. jejuni isolates 55.9% and 13.7% were resistant to ciprofloxacin and tetracycline, respectively. Replacement of Thr86 with Ile in GyrA and a plasmid-borne tet(O) gene were the main resistance mechanisms for fluoroquinolones and tetracycline, respectively.

The human digestive tract is the living environment for billions of cells of various microorganisms that are part of the human microflora. The use of modern molecular biology techniques, such as NGS (Next Generation Sequencing), made it possible to study the microorganisms inhabiting the intestines and to understand their impact on human health. The gut microbiota plays a significant role in the synthesis and metabolism of many nutrients and metabolites, including short-chain fatty acids (SCFA), amino acids, lipids, bile acids and vitamins. Many factors such as diet, age, climate, and socioeconomic conditions influence the diversity of the microbiota. Rapid changes in the composition of the microbiota (disturbance of homeostasis) can lead to dysbiosis - a condition associated not only with intestinal disorders, but also with numerous extraintestinal diseases. The present work is a review of current reports on: research techniques used to analyze microbiota, the impact of various factors on its diversity and the impact of microbiota on our health.