title: Prevalence of β-lactamase classes A, C, and D among clinical isolates of Pseudomonas aeruginosa from a tertiary-level hospital in Bangkok, Thailand.
abstract: Pseudomonas aeruginosa is one of the most important causes of nosocomial infection and it has increasing resistance to many antimicrobial agents. β-lactamase production is the most frequent mechanism for β-lactam resistance in P. aeruginosa. We evaluated the prevalence of β-lactamase genes in P. aeruginosa for classes A, C, and D by polymerase chain reaction, and investigated clonal diversity by pulsed-field gel electrophoresis (PFGE). We used the disk diffusion method to test 118 non-duplicate clinical isolates of P. aeruginosa for antimicrobial susceptibility. We identified 51 isolates (43.22%) as multidrug-resistant P. aeruginosa, approximately 44.91% of which were resistant to ceftazidime. β-lactamase genes were found in 80 isolates of P. aeruginosa (67.80%). The genes that encode VEB-1, AmpC, and OXA-10 were detected in 9 (7.62%), 75 (63.56%), and 18 (15.25%) of these isolates, respectively. The genes that encode PER-1, CTX-M, TEM-1 and derivatives, and SHV-1 were not found in any of the P. aeruginosa isolates. We identified 29 different pulsotypes by PFGE. Two predominant pulsotypes were found. In pulsotype 1, OXA- 10, which was co-produced with the AmpC gene, was predominant. Moreover, VEB-1-producing strains were found to be scattered in many pulsotypes, and AmpC-producing strains showed high pulsotype diversity. The prevalence of β-lactamase genes in P. aeruginosa was represented by the genetic heterogeneity of OXA-10, AmpC, and VEB-1. The predominant clone of P. aeruginosa clinical isolates was OXA-10. This raises concern about oxacillinases among P. aeruginosa clinical isolates.
authors.affiliation: Department of Clinical Chemistry and the Graduate Programme in Clinical Biochemistry and Molecular Medicine, The Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
authors.forename: C
authors.initials: C
authors.lastname: Katvoravutthichai
authors.affiliation: Department of Transfusion Medicine and Clinical Microbiology, The Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
authors.forename: K
authors.initials: K
authors.lastname: Boonbumrung
authors.affiliation: Department of Transfusion Medicine and Clinical Microbiology, The Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand Rachaneeporn.T@chula.ac.th.
authors.forename: R
authors.initials: R
authors.lastname: Tiyawisutsri
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016521:Electrophoresis, Gel, Pulsed-Field; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D062606:Tertiary Care Centers; D013785:Thailand; D018440:beta-Lactam Resistance / Q000187:drug effects; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases