Occurrence and mechanisms of amikacin resistance and its association with beta-lactamases in Pseudomonas aeruginosa: a Korean nationwide study.
OBJECTIVE
We investigated the occurrence and mechanism of amikacin resistance and its association with various beta-lactamase genes in Pseudomonas aeruginosa isolates.


METHODS
Of the total 250 consecutive, non-duplicated isolates of P. aeruginosa, 55 isolates showed amikacin resistance. PCR amplification of genes for aminoglycoside (AG)-modifying enzymes [aac(3)-I, aac(3)-II/VI, aac(3)-III/IV, aac(6')-I, aac(6')-II, ant(2'')-I, ant(4')-II and aph(3')-VI], 16S rRNA methylases (rmtA, rmtB, rmtC and armA) and class 1 integrons was performed. In addition, we analysed the association of AG resistance genes with various beta-lactamase genes.


CONCLUSIONS
In Korea, the amikacin resistance rate in P. aeruginosa was high (22%), and it varied among provinces (3.8% to 40%). Four types of AG-modifying enzyme genes [aph(3')-VI, ant(2'')-I, aac(6')-I and aac(3)-II/VI] were found in 48 isolates. Thirty-six strains harboured two or more types of enzymes, of which a combination of aph(3')-VI and ant(2'')-I was the most frequent (24/36 isolates, 66.7%). None harboured aac(3)-I, aac(3)-III/IV, aac(6')-II, ant(4')-II, rmtA, rmtB, rmtC or armA. Forty-two isolates co-harboured beta-lactamase genes (mostly bla(OXA-10)). A class 1 integron was detected in all but one, and all the ant(2'')-I and 26/29 bla(OXA-10) were found in it. In contrast, aph(3')-VI was not found to be associated with the class 1 integron. Considering the possibility of co-selection and dissemination, constant monitoring of resistance evolution is necessary.
Kim
Ja-Young
JY
Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Park
Yeon-Joon
YJ
Kwon
Hi Jeong
HJ
Han
Kyungja
K
Kang
Moon Won
MW
Woo
Gun-Jo
GJ
D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D007723:Korea; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D000583:Amikacin; D001618:beta-Lactamases