Occurrence, genetic diversity and antibiotic resistance of Arcobacter sp. in a dairy plant

A multiplex PCR assay with five primers targeting the 16S and 23S rRNA genes was developed for the simultaneous detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii. The selected primers amplify a 257-bp fragment from A. cryaerophilus, a 401-bp fragment from A. butzleri and a 641-bp fragment from A. skirrowii. No PCR product was generated for closely related bacteria including Campylobacter and Helicobacter species. The assay was useful to identify cultures after in vitro cultivation and to detect and identify A. butlzeri and A. cryaerophilus from poultry samples present in 24-h old enrichment in Arcobacter broth with cefoperazone, amphotericin and teicoplanin (CAT)-supplement.

A slightly curved, rod-shaped marine bacterium, designated strain CL-S1(T), was isolated from near Dokdo, an island in the East Sea, Korea. Cells were Gram-negative and grew well under either aerobic or microaerobic conditions. Analyses of the 16S rRNA and gyrA gene sequences of strain CL-S1(T) revealed an affiliation with the genus Arcobacter within the class Epsilonproteobacteria. Phylogenetic analyses based on 16S rRNA and gyrA gene sequences showed that strain CL-S1(T) formed a robust clade with Arcobacter halophilus LA31B(T), with sequence similarities of 96.1 and 88.2 %, respectively. DNA-DNA relatedness between strain CL-S1(T) and A. halophilus DSM 18005(T) was 44 %, indicating that they represent genomically distinct species. Strain CL-S1(T) grew optimally at 30-37 degrees C, at pH 7 and in the presence of 3-5 % NaCl. The dominant cellular fatty acids were iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c (28.4 %), C(16 : 0) (26.2 %) and C(18 : 1)omega7c (22.3 %). The DNA G+C content of strain CL-S1(T) was 28 mol%. Strain CL-S1(T) differed phenotypically from A. halophilus LA31B(T) based on its ability to grow aerobically at 10 degrees C and inability to grow under anaerobic conditions. Based on the data presented, strain CL-S1(T) is considered to represent a novel species of the genus Arcobacter, for which the name Arcobacter marinus sp. nov. is proposed. The type strain is CL-S1(T) (=KCCM 90072(T) =JCM 15502(T)).

The nucleotide sequence of the gyrA gene of Arcobacter butzleri, Arcobacter cryaerophilus, Arcobacter cibarius, and Arcobacter skirrowii was determined. The deduced GyrA proteins are closely related to those of Wolinella succinogenes and Helicobacter pullorum, whereas those of Campylobacter species showed less sequence identity. The phylogenetic analysis of GyrA sequences provides a result similar to 16S rRNA gene sequence phylogenetic analysis and allows the discrimination among A. butzleri species. In addition, a Thr-->Ile mutation at amino acid 85 in the quinolone resistance-determining region was associated with ciprofloxacin resistance for two A. butzleri and one A. cryaerophilus ciprofloxacin-resistant strains.