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J Antimicrob Chemother. 2019 Aug 20. pii: dkz346. doi: 10.1093/jac/dkz346. [Epub ahead of print]

Association between Pseudomonas aeruginosa O-antigen serotypes, resistance profiles and high-risk clones: results from a Spanish nationwide survey.

Author information

Servicio de Microbiología, Hospital Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, España.
Servicio de Microbiología, Hospital Universitario La Coruña, Instituto Investigación Biomédica A Coruña (INIBIC), A Coruña, España.
Unidad de Gestión Clínica de Microbiología, Hospital Reina Sofía, Departamento de Microbiología, Universidad de Córdoba, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, España.



To evaluate the correlation of O-antigen serotypes with resistance profiles and high-risk clones in a Spanish nationwide survey.


Up to 30 consecutive healthcare-associated Pseudomonas aeruginosa isolates were collected during October 2017 from each of 51 hospitals (covering all Spanish regions) with a total of 1445 isolates studied. MICs of 13 antipseudomonal agents and MDR/XDR profiles had been previously determined, as well as whole-genome sequences of 185 representative XDR isolates. O-antigen serotypes (O1-O16) were determined by agglutination using serotype-specific antisera (BioRad). The Pseudomonas aeruginosa serotyper (PAst) program was used for in silico serotyping.


The most frequent serotypes were O6 (17.8%), O1 (15.4%) and O11 (13.3%). In contrast, the most frequent serotype among XDR isolates (17.3%) was O4 (34.1%), distantly followed by O11 (15.9%). Within serotypes, XDR phenotypes were more frequent for O12 (60.0%) and O4 (57.3%). The most frequent clone among the XDR isolates was ST175 (40.9%), followed by CC235 (10.7%), ST308 (5.2%) and CC111 (3.6%). Up to 81.6% of XDR ST175 isolates typed O4, whereas 18.4% were non-typeable. O4 genotype was detected in all sequenced (n = 55) ST175 isolates. On the other hand, CC235 and ST308 were associated with O11, whereas CC111 was linked to serotype O12.


O4 serotype is linked to the MDR/XDR profile of widespread ST175 (typically only susceptible to colistin, amikacin and the novel combinations ceftolozane/tazobactam and ceftazidime/avibactam) and therefore, after local validation, its detection in the microbiology laboratory might be useful for guiding semi-empirical antipseudomonal therapies and infection control measures in Spanish hospitals.


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