Emergence of metallo-b-lactamase producing Pseudomonas aeruginosa and Klebsiella pneumoniae in Scandinavia

Abstract number: O89

Samuelsen Ø., Buarø L., Aasnæs B., Fuursted K., Haldorsen B., Leegaard T., Rajendra Y., Rydberg J., Simonsen G.S., Toleman M.A., Walder M., Yong D., Walsh T.R., Sundsfjord A., Giske C.G.

Objectives: Scandinavian countries have a history of low levels of antibiotic resistance due to effective infection control measures and restricted use of antibiotics. New resistance mechanisms are therefore less likely to emerge from endogenous sources. This study assesses the epidemiology and characterisation of MBL producing clinical isolates detected in Denmark, Norway, and Sweden between 2003–2007.

Methods: MBL genes and their genetic support were evaluated by PCR and DNA sequencing, while epidemiological typing of host isolates was performed by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and serotyping. Susceptibility testing was performed with Etest.

Results: Since the first MBL positive isolate was identified in Sweden in 2003, a total of 17 MBL isolates have been identified in Norway, Sweden and Denmark by 2007, including eleven Pseudomonas aeruginosa strains and six Klebsiella pneumoniae strains. Many of the infected patients have a history of recent hospitalisation outside Scandinavia including Southern-Europe, Asia and Africa. However, MBL isolates are now being identified in patients precluding travel or hospitalisation outside Scandinavia in the last twelve months. VIM-enzymes constitute the predominant MBL genotype, found in all K. pneumoniae isolates and ten P. aeruginosa isolates. IMP was detected in one P. aeruginosa isolate. Genetic characterisation of the isolates revealed that the genes encoding MBL are located in class 1 integrons including TniC-class 1 integrons of variable size and with a plethora of other resistance gene cassettes. Accordingly, the susceptibility profiles of the isolates show a multi-drug resistant phenotype and some isolates are only susceptible to colistin. Interestingly, the qnrS gene, conferring low-level quinolone resistance, was identified in the two Norwegian K. pneumoniae isolates. Serotyping of P. aeruginosa indicate that O11 and O12 isolates predominate, and some isolates within the serotypes were found to be related by PFGE and MLST.

Conclusion: The spread of MBL-producing clinical isolates to Scandinavia is likely to initially have occurred through importation of the MBL positive isolates. However, such isolates have now appeared in patients with no history of travel or hospitalisation outside Scandinavia. VIM was the dominant MBL and always present in a multi-drug resistant background. PFGE and MLST revealed that some isolates of the same serotype were related.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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