The plasmid pUUH239.2 is a composite of the pKPN3 K. pneumoniae plasmid backbone and the bla(CTX-M-15)-encoding multiresistance cassette associated with the internationally recognized outbreak strain E. coli ST131. The resulting plasmid differs in stability between K. pneumoniae and E. coli, and this has probably limited the spread of this plasmid during the outbreak.

OBJECTIVES. Surgical site infections (SSIs) may be devastating for the patient and they carry high economic costs. Studies of SSI after neurosurgery report an incidence of 1-11%. However, patient material, follow-up time and definition of SSI have varied. In the present study we prospectively recorded the prevalence of SSI 3 months after standard intracranial neurosurgical procedures. The incidence, impact and risk factors of SSI were analysed. METHODS. We included patients admitted during 2010 to our unit for postoperative care after standard neurosurgical procedures. SSI was defined as evident with positive cultures from surgical samples or CSF, and/or purulent discharge during reoperation. Follow-up was done after 3 and 12 months and statistics was obtained after 3 months. The predictive values on the outcome of demographic and clinical factors describing the surgical procedure were evaluated using linear regression. RESULTS. A total of 448 patients were included in the study and underwent a total of 466 procedures. Within 3 and 12 months, 33 and 88 patients, respectively, had died. Of the surviving patients, 20 (4.3% of procedures) developed infections within 3 months and another 3 (4.9% of procedures) within 12 months. Risk factors for SSI were meningioma, longer operation time, craniotomy, dural substitute, and staples in wound closure. Patients with SSI had significantly longer hospital stay. Multivariate analysis showed that factors found significant in univariate analysis frequently occur together. DISCUSSION. We studied the prevalence of SSI after 3 and 12 months in a prospective 1-year material with standard neurosurgical procedures and found it to be 4.3% and 4.9%, respectively. The analysis of the results showed that a combination of parameters indicating a longer and more complicated procedure predicted the development of SSI. Our conclusion is that the prevention of SSI has to be done at many levels, especially with patients undergoing long surgical procedures.

Between May and December 2005, 64 multidrug-resistant isolates of Klebsiella pneumoniae were detected from patients admitted to Uppsala University Hospital. This represented a dramatic increase in ESBL-producing K. pneumoniae compared to previous years. To investigate the epidemiology and to characterize the resistance mechanisms of the isolates, a study was initiated. Antibiotic susceptibility was determined by means of the Etest and the disc diffusion method. Extended-spectrum beta-lactamase (ESBL) production was identified by clavulanic acid synergy test and confirmed with PCR amplification followed by DNA sequencing. DNA profiles of the isolates were examined with pulsed-field gel electrophoresis (PFGE). All isolates were resistant or exhibited reduced susceptibility to cefadroxil, cefuroxime, cefotaxime, ceftazidime, aztreonam, piperacillin/tazobactam, ciprofloxacin, tobramycin, and trimethoprim-sulfamethoxazole. They produced ESBL of the CTX-M-15 type, and the involvement of a single K. pneumoniae clone was shown. This is the first major clonal outbreak of multiresistant ESBL-producing K. pneumoniae in Scandinavia. The outbreak demonstrates the epidemic potential of enterobacteria containing ESBLs of the CTX-M type, even in a country with a relatively low selective pressure and a low prevalence of multiresistant bacteria.

Vancomycin-resistant enterococci (VRE) are a challenge to the health-care system regarding transmission rate and treatment of infections. VRE outbreaks have to be controlled from the first cases which means that appropriate and sensitive genotyping methods are needed. The aim of this study was to investigate the applicability of whole genome sequencing based analysis compared to Pulsed-Field Gel Electrophoresis (PFGE) and Multi-Locus Sequence Typing (MLST) in epidemiological investigations as well as the development of a user friendly method for daily laboratory use. Out of 14,000 VRE - screening samples, a total of 60 isolates positive for either vanA or vanB gene were isolated of which 38 were from patients with epidemiological links from three suspected outbreaks at Uppsala University Hospital. The isolates were genotypically characterised with PFGE, MLST, and WGS based core genome Average Nucleotide Identity analysis (cgANI). PFGE was compared to WGS and MLST regarding reliability, resolution, and applicability capacity. The PFGE analysis of the 38 isolates confirmed the epidemiological investigation that three outbreaks had occurred but gave an unclear picture for the largest cluster. The WGS analysis could clearly distinguish six ANI clusters for those 38 isolates. As result of the comparison of the investigated methods, we recommend WGS-ANI analysis for epidemiological issues with VRE. The recommended threshold for Enterococcus faecium VRE outbreak strain delineation with core genome based ANI is 98.5%. All referred sequences of this study are available from the NCBI BioProject number PRJNA301929.

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