High prevalence of OXA-51-type class D beta-lactamases among ceftazidime-resistant clinical isolates of Acinetobacter spp.: co-existence with OXA-58 in multiple centres.
OBJECTIVE
This study was designed to demonstrate the prevalence of the newly discovered carbapenem-hydrolysing class D enzymes, OXA-51-type and OXA-58, among clinical isolates of Acinetobacter spp.


METHODS
A total of 72 isolates from six centres were studied. Isolates were screened by PCR with specific primers for bla(OXA-51-type) and bla(OXA-58). PCR products were sequence-analysed. Plasmids were digested with EcoRV and genomic DNAs were digested with PvuII. Hybridization experiments were done with digoxigenin-labelled specific probes. Macro-restriction analysis was done on SmaI-digested genomic DNAs.


RESULTS
A total of 56 (77.8%) isolates were positive for bla(OXA-51-type) genes. Sequence analysis of the products from 23 selected isolates revealed the occurrence of multiple alleles in all contributing centres. The bla(OXA-58) gene was detected among 10 isolates from five centres. All were also positive for bla(OXA-51-type) genes. Among the bla(OXA-58)-positive isolates, two from the same centre were positive for a novel OXA-51 allele (OXA-86). Southern hybridization of plasmids and of genomic DNAs suggested that bla(OXA-51-type) genes are located on chromosomes whereas bla(OXA-58) genes are plasmid borne in these 10 isolates. Plasmid profiles and pulsed-field gel electrophoresis patterns indicated the spread of the bla(OXA-58) gene among multiple clones. The bla(OXA-51-type) and bla(OXA-58) co-carrier strains were mostly associated with a pandrug-resistant phenotype.


CONCLUSIONS
This study indicated that bla(OXA-58)-bearing plasmids are readily spreading among multiple clones of the bla(OXA-51-type)-bearing clinical isolates of Acinetobacter spp. Since these isolates are highly resistant to antibiotics this finding indicates the existence of a significant problem in Turkish hospitals.
Vahaboglu
Haluk
H
Enfeksiyon Hast. & Klin Mikrobiyoloji AD, Kocaeli Universitesi, Kocaeli, Turkey. vahabo@hotmail.com
Budak
Fatma
F
Kasap
Murat
M
Gacar
Gulcin
G
Torol
Sinem
S
Karadenizli
Aynur
A
Kolayli
Fetiye
F
Eroglu
Cafer
C
D000150:Acinetobacter / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D000483:Alleles; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015139:Blotting, Southern; D002442:Ceftazidime / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015995:Prevalence; D014421:Turkey / Q000453:epidemiology; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D002442:Ceftazidime; D001618:beta-Lactamases