Emergence of OXA-carbapenemase- and 16S rRNA methylase-producing international clones of Acinetobacter baumannii in Norway

Abstract

This study was designed to investigate the molecular epidemiology and antibiotic-resistance characteristics of 11 carbapenem-resistant clinical isolates of Acinetobacter baumannii obtained in Norway between 2004 and 2009. Interestingly, all the isolates were linked with recent hospitalization outside Norway. The epidemiological status was investigated by multilocus sequence typing (MLST), multiplex PCR assays for major international clones, typing of bla OXA-51 -like variants and PFGE. The genotypic-resistance characteristics, including the occurrence of OXA-carbapenemase-encoding and 16S rRNA methylase-encoding genes and class 1 integrons, were investigated by PCR assays and sequencing. Seven isolates were found to harbour bla OXA-66 and belong to MLST clonal complexes (CCs) CC2 P (Pasteur Institute scheme) and CC92 B (Bartual scheme), and international clone II. One isolate harboured bla OXA-69 , and belonged to CC1 P , CC109 B and international clone I. Two isolates belonged to sequence group 9, probably a subgroup of international clone I, and one isolate belonged to sequence group 4, a proposed novel international clone. All isolates contained an acquired OXAcarbapenemase-encoding gene: bla OXA-23 -like (n59), bla OXA-24 -like (n51) and bla OXA-58 -like (n51). Four isolates with high-level aminoglycoside-resistance contained the 16S rRNA methylase-encoding armA gene. Class 1 integrons with six different variable regions were detected. Sequence analysis of gene cassettes identified four aminoglycoside (aacA4, aac(69)-Im, aadA1 and aacC1), two chloramphenicol (catB8 and cm1A5), one b-lactamase (bla and one rifampicin (arr-2) resistance gene in various combinations. In conclusion, the occurrence of A. baumannii isolates producing OXA carbapenemase and 16S rRNA methylase in Norway was related to the worldwide distribution of international clones I and II, and the emergence of novel international clones.

OXA β-Lactamases

“…Unlike MLST, PFGE can identify small differences between isolates within a clonal outbreak, and as such, it is very useful for local epidemiological purposes. While PFGE data are often consistent with MLST data (154), it is not unusual for isolates to have the same MLST sequence type but to produce different PFGE patterns (152,165,166). Another commonly used method is repetitive sequence-based PCR (rep-PCR) using the DiversiLab system (52), and the discriminative power of this system is similar to that of PFGE.…”

“…Another commonly used method is repetitive sequence-based PCR (rep-PCR) using the DiversiLab system (52), and the discriminative power of this system is similar to that of PFGE. The use of these techniques and comparing them with bla OXA gene content illustrated the degree of mobility that the bla OXA genes have, where isolates with the same PFGE or rep-PCR profile vary in their bla OXA gene content (137,138,167) or isolates with different profiles can have the same bla OXA gene content (152,167,168). The use of such techniques with high discriminatory power is useful in outbreak situations, where, when used in conjunction with bla OXA gene screening, they can be used to detect small changes in local epidemiology, such as the acquisition of a resistance gene or conversion between one allele of a resistance gene and another (55,169).…”

The Genetic Characteristics of Multidrug-resistantAcinetobacter baumanniiCoproducing 16S rRNA MethylasearmAand Carbapenemase OXA-23

“…Recently in several studies of A. baumannii coproducing armA and carbapenemase in South Korea (16,17) and other parts of the world were reported (10,18,19), which can pose significant therapeutic threat.…”

Widespread dissemination of multidrug-resistant Acinetobacter baumannii producing OXA-23 carbapenemase and ArmA 16S ribosomal RNA methylase in a Bulgarian university hospital

“…Recently, North American, 4 Western European, 5 and Asian 6,7 studies have documented the co-existence of bla OXA-23 and armA, which can pose therapeutic challenges. This study illustrates the inter-country dissemination of 16S rRNA methylase and OXA-23-producing nosocomial A. baumannii isolates.…”