Characterization of carbapenem-resistant Acinetobacter baumannii in Brazil (2008–2011): countrywide spread of OXA-23–producing clones (CC15 and CC79)

Abstract

The study investigated the genetic relationship of carbapenem-resistant Acinetobacter baumannii clinical isolated from inpatients during 2008-2011 from 11 Brazilian states. Antimicrobial susceptibility profile was determined by disc diffusion method and Etest. Polymerase chain reaction was applied for carbapenemase genes, and ISAba1. Isolates were subjected to pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) for molecular typing. Most of the isolates showed high resistance rates to antibiotics tested. The blaOXA-51-like gene was found in all isolates, and 146 (94.2%) isolates were positive for blaOXA-23-like. In the most OXA-23-producing isolates, the blaOXA-23-like gene was accompanied by ISAba1. A total of 146 OXA-23-producing isolates were clustered into 28 genotypes by PFGE. Molecular analysis by MLST identified 13 sequence types (STs). The most prevalent PFGE profiles were designated as ST15 (CC15), ST1 (CC1), and ST79 (CC79). This study showed the widespread of clonal complexes of A. baumannii harboring the blaOXA-23-like gene in different Brazilian states.

High Prevalence of bla NDM-1 Carbapenemase-Encoding Gene and 16S rRNA armA Methyltransferase Gene among Acinetobacter baumannii Clinical Isolates in Egypt

“…We found that bla NDM-1 , bla , and armA were collocated on plasmids in 8/25 (32%) extracted isolates. This is in accordance with previous reports showing that bla , bla NDM-1 , and armA genes in A. baumannii are mostly located on plasmids (16,19,20). Similarly, AMEencoding genes [ant (2), aad, aac (6), aph, and aac(3)] were found to be plasmidic.…”

“…All the MHT-negative isolates (25/150) were found to be negative for the tested carbapenemase-encoding genes. It is well known that bla and bla OXA-51 are regulated in part by ISAba1, which may be located upstream of these genes acting as a promoter and resulting in the overexpression of these genes and in a high level of carbapenem resistance (16,17). In our study ISAba1 was found upstream of the bla OXA-23 -like and bla OXA-51 -like genes in 91.3% (137/150) and 4.7% (7/150) of our isolates, respectively.…”

Population Structure Analysis of Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates from Brazil Reveals Predominance of Clonal Complexes 1, 15, and 79

“…It is remarkable that we detected the occurrence of strains belonging to CC25 (ST25, three strains). CC25 had already been detected in Brazil at low frequencies, and those strains were associated with the bla OXA-23 (16) and bla NDM-1 (21) genes. Although we did not detect the bla NDM gene in our strains, NDM enzymes are emerging in the Brazilian territory (21), including in different Acinetobacter species (22), which is an alert for the need for surveillance of this threatening combination.…”

Old Clinical Isolates of Acinetobacter seifertii in Brazil Producing OXA-58

“…The studied strains were detected 4 years apart and belonged to the same PFGE clone; however, the clone source and reservoir remained undetermined. In fact, bla OXA-58 is rarely reported in Brazil (23), where bla OXA-23 and bla have been the most predominant CHDL genes (23,24). The presence of carbapenemase-encoding genes in non-baumannii species exhibiting decreased susceptibility to polymyxins is a cause of great concern, because it drastically limits the available therapeutic options for treatment of such infections.…”