Evaluation of a new trilocus sequence-based multiplex-PCR to detect major Acinetobacter baumannii clonal complexes...

Dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB) is mainly due to the spread of clonal lineages, particularly those included into the clonal complexes (CC) CC1, CC2, CC15, CC25, and CC79. We evaluated the usefulness of a recently modified PCR-based trilocus sequence-based typing (m3LST) in comparison with the standard multilocus sequence typing (MSLT) of 7 housekeeping genes as per the Institute Pasteur Scheme to assign the clonal complexes in CRAB. A collection of 78 CRAB isolated from 67 different Brazilian health institutions was submitted to both methodologies, and concordance rate was calculated. The collection studied included mainly isolates belonging to endemic Brazilian Clonal Complexes (CC1, CC15, CC25 and CC79, n=72, 92.3%) but also singletons sequence types (ST) with low prevalence in the country (ST107, ST113, ST188, ST317, ST584, ST733, n=6; 7.7%). The m3LST correctly assigned all the isolates into the main CC responsible for the CRAB dissemination in Brazil. All the singletons ST were not misidentified as prevalent lineages. The PCR-based m3LST is a powerful tool to investigate molecular epidemiology of A. baumannii representative of prevalent Brazilian clonal complexes 1, 15, 25 and 79.