title: Molecular analysis of a prolonged spread of Klebsiella pneumoniae co-producing DHA-1 and SHV-12 β-lactamases.
abstract: The study investigated molecular mechanisms for prolonged nosocomial spread of multidrug-resistant Klebsiella pneumoniae co-producing plasmid-mediated AmpC β-lactamase DHA-1 and extended-spectrum β-lactamase SHV-12. Forty-eight clinical isolates of K. pneumonia, resistant to the extended-spectrum cepha-losporins, were collected in a 750-bed university hospital over a year. The isolates were characterized for PCR-based β-lactamase genotypes, isoelectric focusing and pulsed-field gel electrophoresis (PFGE) profiles. Resistance transfer was performed by plasmid conjugation and confirmed by a duplex-PCR and Southern hybridization. On β-lactamase typing, the strains producing only the DHA-1 enzyme (n=17) or co-producing DHA-1 and SHV-12 enzymes (n=15) were predominant. Judging from a one year-distribution of PFGE profiles, the co-producer was spread primarily with single clonal expansion of the PFGE-type A with subtypes (n=14), whereas the strains producing only DHA-1 enzyme were spread simultaneously with the PFGE-type A (n=ll) and other PFGE types (n=6). Transconjugants of the co-producers were confirmed to harbor either both bla (DHA-1) and bla (SHV-12) or only the bla (DHA-1). In conclusion, this study indicated that the persistent nosocomial spread of multidrug-resistant K. pneumoniae strains was primarily associated with expansion of a clone harboring both the bla (DHA-1) and bla (SHV-12) or the bla (DHA-1) only, and to a lesser extent with the horizontal transfer of the resistant plasmids. Our observations have clinical implication for the control and prevention of nosocomial dissemination of multidrug-resistant K. pneumoniae strains.
authors: Department of Internal Medicine, Division of Infectious Diseases, Seoul, Republic of Korea.
authors: Young Kyung
authors: YK
authors: Yoon
authors: Hye Won
authors: HW
authors: Cheong
authors: Hyunjoo
authors: H
authors: Pai
authors: Kyoung Ho
authors: KH
authors: Roh
authors: Jeong Yeon
authors: JY
authors: Kim
authors: Dae Won
authors: DW
authors: Park
authors: Jang Wook
authors: JW
authors: Sohn
authors: Seung Eun
authors: SE
authors: Lee
authors: Byung Chul
authors: BC
authors: Chun
authors: Hee Sun
authors: HS
authors: Sim
authors: Min Ja
authors: MJ
authors: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006785:Hospitals, University / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D056910:Republic of Korea; D055815:Young Adult; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C107198:beta-lactamase SHV-12; C048795:AmpC beta-lactamases; D001618:beta-Lactamases