RCH51, a multiply antibiotic-resistant Acinetobacter baumannii ST103IP isolate, carries resistance genes in three plasmids, including a novel potentially conjugative plasmid carrying oxa235 in transposon Tn6252.
To determine the identity and context of genes conferring antibiotic resistance in a sporadic multiply antibiotic-resistant Acinetobacter baumannii recovered at Royal Children's Hospital, Brisbane.



The antibiotic resistance phenotype for 23 antibiotics was determined using disc diffusion or MIC determination. The whole-genome sequence of RCH51 was determined using the Illumina HiSeq platform. Antibiotic resistance determinants were identified using ResFinder. Plasmids were recovered by transformation.



Isolate RCH51 belongs to the uncommon STs ST103 IP (7-3-2-1-7-1-4) and ST514 OX (1-52-29-28-18-114-7). It was found to be resistant to sulfamethoxazole, tetracycline, gentamicin, tobramycin and kanamycin and also exhibited reduced susceptibility to imipenem (MIC 2 mg/L) and meropenem (MIC 6 mg/L). RCH51 carries the oxa235 , sul2 , floR , aadB and tet39 resistance genes, all located on plasmids. The largest of the three plasmids, pRCH51-3, is 52 789 bp and carries oxa235 in the ISAba1-bounded transposon Tn 6252 , as well as sul2 and floR . pRCH51-3 represents a new A. baumannii plasmid family that is potentially conjugative as it contains several genes predicted to encode transfer functions. However, conjugation of pRCH51-3 was not detected. The aadB and tet39 resistance genes were each found in small plasmids identical to the known plasmids pRAY*-v1 and pRCH52-1, respectively.



The resistance gene complement of RCH51 was found in three plasmids. pRCH51-3, which carries the oxa235 , sul2 and floR resistance genes, represents a new, potentially conjugative A. baumannii plasmid type.
School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
Mohammad
M
Hamidian
School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
Steven J
SJ
Nigro
School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
Rebecca M
RM
Hartstein
School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
Ruth M
RM
Hall
D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016680:Genome, Bacterial; D044404:Genomic Islands; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D017422:Sequence Analysis, DNA; D014031:Tobramycin / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005839:Gentamicins; D001618:beta-Lactamases; D014031:Tobramycin