To compare commonly used phenotypic methods with genotypic identification methods 47 clinical isolates of coagulase-negative staphylococci (CONS), 10 CONS ATCC strains, and a Staphylococcus aureus clinical isolate were identified using the API Staph ID test, BD Phoenix Automated Microbiology System, and 16S rRNA gene and tuf gene sequencing. When necessary part of the sodA gene was sequenced for definitive identification. The results show that tuf gene sequencing is the best method for identification of CONS, but the API Staph ID test is a reasonably reliable phenotypic alternative. The performance of the BD Phoenix Automated Microbiology System for identification of CONS is poor. The present study also showed that although genotypic methods are clearly superior to phenotypic identifications, a drawback of sequence-based genotypic methods may be a lack of quality of deposited sequences in data banks. In particular, 16S rRNA gene sequencing suffers from the lack of high quality among sequences deposited in GenBank. Furthermore, genotypic identification based on 16S rRNA sequences has limited discriminating power for closely related Staphylococcus species. We propose partial sequencing of the tuf gene as a reliable and reproducible method for identification of CONS species.

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A high occurrence of ESBL-producing E. coli in faecal samples was found among horses in an equine clinic and the variety of STs, ESBL genes and plasmid types suggests nosocomial transmission. ESBL E. coli can cause difficult-to-treat infections in horses and prudent use of antimicrobials is warranted. A further assessment of the risks of transmission to persons in close contact with horses, such as caretakers or veterinarians, is crucial.

No relation between the presence of tetracycline resistance determinants tet(A) to tet(E) and the MICs of tigecycline was observed for Enterobacteriaceae, although tetracycline-susceptible isolates were more susceptible overall to tigecycline, whereas the presence of tet(M) in Staphylococcus aureus was associated with higher MICs of minocycline.

ObjectiveTo investigate the molecular characteristics of extended-spectrum cephalosporin (ESC)-resistant Enterobacteriaceae collected during a cross-sectional study examining the prevalence and risk factors for faecal carriage of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in humans living in areas with high or low broiler density.MethodsESC-resistant Enterobacteriaceae were identified by combination disc-diffusion test. ESBL/AmpC/carbapenemase genes were analysed using PCR and sequencing. For E. coli, phylogenetic groups and MLST were determined. Plasmids were characterized by transformation and PCR-based replicon typing. Subtyping of plasmids was done by plasmid multilocus sequence typing.Results175 ESC-resistant Enterobacteriaceae were cultured from 165/1,033 individuals. The isolates were Escherichia coli(n=65), Citrobacter freundii (n=52), Enterobacter cloacae (n=38), Morganella morganii (n=5), Enterobacter aerogenes (n=4), Klebsiella pneumoniae (n=3), Hafnia alvei (n=2), Shigella spp. (n=2), Citrobacter amalonaticus (n=1), Escherichia hermannii (n=1), Kluyvera cryocrescens (n=1), and Pantoea agglomerans (n=1). The following ESBL genes were recovered in 55 isolates originating from 49 of 1,033 (4.7 %) persons: bla CTX-M-1 (n=17), bla CTX-M-15 (n=16), bla CTX-M-14 (n=9), bla CTX-M-2 (n=3), bla CTX-M-3 (n=2), bla CTX-M-24 (n=2), bla CTX-M-27 (n=1), bla CTX-M-32 (n=1), bla SHV-12 (n=2), bla SHV-65 (n=1) and bla TEM-52 (n=1). Plasmidic AmpC (pAmpC) genes were discovered in 6 out of 1,033 (0.6 %) persons. One person carried two different E. coli isolates, one with bla CTX-M-1 and the other with bla CMY-2 and therefore the prevalence of persons carrying Enterobacteriaceae harboring ESBL and/or pAmpC genes was 5.2 %. In eight E. coli isolates the AmpC phenotype was caused by mutations in the AmpC promoter region. No carbapenemase genes were identified. A large variety of E. coli genotypes was found, ST131 and ST10 being most common.ConclusionsESBL/pAmpC genes resembled those from patients in Dutch hospitals, indicating that healthy humans form a reservoir for transmission of these determinants to vulnerable people. The role of poultry in the transmission to humans in the community remains to be elucidated.