Genomic and Clinical Characterization of IMP-1-Producing Multidrug-Resistant Acinetobacter bereziniae Isolates from Bloodstream Infections in a Brazilian Tertiary Hospital.

Acinetobacter baumannii is the main species of the Acinetobacter genus; however, non-baumannii Acinetobacter (NBA) species causing infections have been described for the past years, as well as antimicrobial resistance. In this study, we describe the occurrence of two multidrug-resistant (MDR) IMP-1-producing Acinetobacter bereziniae isolates recovered from bloodstream infections in different patients but in the same intensive care unit among 134 carbapenem-resistant Acinetobacter screened. Antimicrobial susceptibility testing revealed resistance to carbapenems, extended spectrum, and antipseudomonad cephalosporins, amikacin, and trimethoprim-sulfamethoxazole. Both A. bereziniae isolates shared the same ApaI-pulsed-field gel electrophoresis (PFGE) pattern. Whole-genome sequencing of both isolates revealed that blaIMP-1 was embedded into an In86 Class I integron carrying also sul1, aac(6')-31, and aadA genes. A new sequence type (ST1309 Pasteur) was deposited. The virulence genes lpxC and ompA, seen in A. baumannii, were detected in the A. bereziniae strains. Recognition of A. bereziniae causing invasive MDR infection underscores the role of NBA species as human pathogens especially in at-risk patients.

Emergence and Persistence of High-Risk Clones Among MDR and XDR A. baumannii at a Brazilian Teaching Hospital.

Dissemination of carbapenem-resistant Acinetobacter baumannii is currently one of the priority themes discussed around the world, including in Brazil, where this pathogen is considered endemic. A total of 107 carbapenem-resistant A. baumannii (CRAB) isolates were collected from patients with bacteraemia attended at a teaching hospital in Brazil from 2008 to 2014. From these samples, 104 (97.2%) carried bla OXA-23-like, all of them associated with ISAba1 The bla OXA-231 (1.9%) and bla OXA-72 (0.9%) genes were also detected in low frequencies. All isolates were susceptible to minocycline, and 38.3% of isolates presented intermediate susceptibility to tigecycline (MIC = 4 µg/ml). Molecular typing assessed by multi-locus sequence typing demonstrated that the strains were mainly associated with clonal complexes CC79 (47.4%), followed by CC1 (16.9%), and CC317 (18.6%), belonging to different pulsotypes and in different prevalences over the years. Changes in the clones' prevalence reinforce the need of identifying and controlling CRAB in hospital settings to preserve the already scarce therapeutic options available.

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

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.