Genetic diversity and clonal characteristics of ciprofloxacin-resistant Campylobacter jejuni isolated from Chilean patients with gastroenteritis.

Campylobacter jejuni is a major cause of acute gastroenteritis worldwide. However, it has also been associated with other diseases such as bacteremia and with several post-infection sequelae. Although campylobacteriosis is usually a self-limited infection, antibiotics are indicated for severe and chronic conditions. Unfortunately, several industrialised nations have reported a substantial increase in antibiotic resistance of C. jejuni. However, there is still a lack of knowledge about the epidemiology of resistance developed by this pathogen in the developing world. For this reason, our objective was to determine the resistance of clinical C. jejuni strains to ciprofloxacin and erythromycin in Chile and their associated genotypes. Fifty C. jejuni isolates recovered from fecal samples of people with acute gastroenteritis, in central and southern Chile between 2006 and 2015, were analysed. Resistance to erythromycin and ciprofloxacin was assessed by disk diffusion and agar dilution methods. Furthermore, these strains were genotyped by Multilocus Sequence Typing (MLST). Only one of the isolates was resistant to erythromycin. However, 48% of them were resistant to ciprofloxacin. The minimal inhibitory concentration of these ciprofloxacin-resistant isolates was in the range between 4 and 32 µg/ml. Moreover, MLST analyses showed that most ciprofloxacin-resistant strains were grouped into three dominant clonal complexes (ST-21, ST-48 and ST-353), while the unique strain resistant to both antibiotics belonged to the ST-45 complex. Our results evidence a high ciprofloxacin resistance and suggest that there is a dissemination of resistant clonal lineages responsible for cases of campylobacteriosis in Chile. Further studies should elucidate the origin of these resistant genotypes.

Campylobacter ornithocola sp. nov., a novel member of the Campylobacter lari group isolated from wild bird faecal samples.

During a study on the prevalence and diversity of campylobacteria in wild birds faecal samples from the city of Valdivia (southern Chile) 17 Gram-stain-negative, curved-rod-shaped isolates, were initially identified as Campylobacter lari by PCR-RFLP. Further identification by 16S rRNA sequence analysis revealed that they formed a distinct group in the genus Campylobacter. This unique position was confirmed by the results of analysis of rpoB, atpA and cpn60 gene sequences. The average nucleotide identity between the representative strain WBE38T and the type strain of the most closely related taxon C. larisubsp.concheus (LMG 11760) was 90.8 %. The oxidase and urease activity of the novel isolates enabled them to be phenotypically differentiated from species of the genus Campylobacter with validly published names. Therefore, on the basis of phenotypic, genetic and genomic characterizations, the results of this study clearly indicate that these strains represent a novel species within the genus Campylobacter, for which the name Campylobacter ornithocola sp. nov. is proposed, with the type strain WBE38T (=CECT 9147T=LMG 29815T).