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

J Antimicrob Chemother. 2019 Nov 1;74(11):3217-3220. doi: 10.1093/jac/dkz346.


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

Methods: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Cephalosporins / pharmacology
  • Computer Simulation
  • Cross Infection / microbiology
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Genotype
  • Hospitals
  • Humans
  • Microbial Sensitivity Tests
  • O Antigens / genetics*
  • Phenotype
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / genetics*
  • Public Health Surveillance
  • Serogroup
  • Serotyping
  • Spain
  • Tazobactam / pharmacology
  • Whole Genome Sequencing


  • Anti-Bacterial Agents
  • Cephalosporins
  • O Antigens
  • ceftolozane, tazobactam drug combination
  • Tazobactam