ABSTRACT
PURPOSE: The molecular epidemiology of Pseudomonas aeruginosa bloodstream infection (BSI) isolates has received limited attention. This study aims to characterize the molecular relationship of P. aeruginosa BSI isolates in the non-outbreak setting at a single tertiary healthcare facility. METHODOLOGY: P. aeruginosa BSI isolates from patients who were admitted to the Royal Brisbane and Women's Hospital over a 13 month period from November 2009 were identified retrospectively from the Pathology Queensland Clinical and Scientific Information System. The isolates were typed by the iPLEX MassARRAY matrix assisted lazer desorption/isonisation time of flight (MALDI-TOF) MS genotyping. The DiversiLab automated rapid strain typing platform (bioMérieux) was used to assess the genotypic relationships between study isolates that showed indistinguishable iPLEX20SNP profiles. Clinical data was also collected retrospectively from patient notes. RESULTS: Fifty-three P. aeruginosa BSI episodes were available for study. Thirty-five different clones or clonal complexes were identified by the iPLEX MassARRAY MALDI-TOF MS genotyping. Seventeen BSI isolates with indistinguishable iPLEX20SNP profiles underwent further DiversiLab genotyping and were found to belong to a further 13 different genotypes. There was no relationship between clonality and acquisition type, source of infection or length of stay in the setting of hospital-acquired infection. CONCLUSION: The non-clonal population structure suggests that there is ongoing environmental exposure of inpatients to P. aeruginosa. In clinical areas dealing with at-risk patients, routine attention to mechanism of environmental colonization is important and should be addressed even in the non-outbreak setting.
Subject(s)
Bacteremia/epidemiology , Cross Infection/epidemiology , Pseudomonas Infections/epidemiology , Pseudomonas aeruginosa/genetics , Adult , Aged , Aged, 80 and over , Bacteremia/blood , Bacterial Typing Techniques , Cloning, Molecular , Cross Infection/blood , Cross Infection/microbiology , DNA, Bacterial/genetics , Female , Genotyping Techniques , Humans , Male , Middle Aged , Molecular Epidemiology , Pseudomonas Infections/blood , Pseudomonas aeruginosa/isolation & purification , Queensland/epidemiology , Retrospective Studies , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Young AdultABSTRACT
Burkholderia cepacia complex (Bcc) comprises nine closely related species or genomovars. It is an important causative agent of opportunistic infections and waterborne nosocomial infections. B. cepacia (formerly genomovar I) was identified from the blood culture of a baby in our neonatal unit (NU) in March 2005. B. cepacia was isolated four times from clinical specimens since the introduction of non-touch taps in the NU from 2000 to 2005 and only once from 1994 to 2000. Environmental samples were collected from the NU, including tap water from non-touch taps. Clinical and environmental isolates of Bcc were characterized using molecular identification and strain typing. A literature review was undertaken to delineate a method for eradication of Bcc. Several variations for hot water eradication of the organism from the taps were attempted. Genotyping and molecular analysis revealed that tap water isolates were B. cenocepacia which was a different species from the B. cepacia isolated from blood cultures of the neonate. However, B. cenocepacia has been known to cause nosocomial outbreaks and it was eventually eradicated from the NU by using repeated thermal shock (hot water at 65 degrees C for 10 min), changing taps and decolonizing sinks with hypochlorite. Molecular typing is useful in assisting the investigation of Bcc nosocomial infections.
