Artikel
An Outbreak of Nosocomial Infection Caused by Multidrugresistant (MDR) Klebsiella pneumoniae in the Largest Cancer Hospital in Russia
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Veröffentlicht: | 3. Juni 2014 |
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Purpose: To analyze the identity of MDR-Klebsiella pneumoniae strains isolated from patients and hospital environment during the outbreak in September 2013.
Methods: Total 35 MDR K.pneumonie isolates were analysed. 22 isolates were from patients after operations on the thorax admitted to surgical ICU (SICU), including 6 from blood, 9 from bronchoscopic materials, 5 from wounds and 2 from urine. 7 patients died from infection. 14 isolates were from objects in the SICU. Biotypes were determined in accordance with the 8-digit expert data processing system (MicroScan WalkAway, “Siemens”). Identification with MALDI-TOF mass-spectrometer (MS) (Microflex, “Bruker”) and cluster analysis by comparing the mass spectra obtained with the available databases using the software package MALDI Biotyper 3.0 was performed.
Results: 22 of 36 (61.1%) strains had 77744372 biotype (16 of them were from patients and 6 – from objects in SICU). 14 strains had biotype 77744272 (13 - from patients and 1 – from hospital environment). The only distinction between these biotypes was in kanamycin (K) resistance: K.pneumoniae biotype 77744372 was K-resistant, and biotype 77744272 was K-sensitive. All isolates of K.pneumonie analyzed were only sensitive to imipenem, amikacin and tigecycline.
Two separate MS-peaks (grey and brown) on dendrogram were found. The Grey peak was obtained for 1 strain isolated from a patient and was not phylogenetically close to other strains studied. The Brown peak accounted for all other studied strains (n=34, 97.1 %) and formed two branches. One branch was formed with one strain, isolated from 1 patient. The second branch included all other strains (n=33) (Figure 1 [Fig. 1]). 7 of them (21.2 %) were obtained from the hospital environment and 26 (78.8%) strains were obtained from patients. In turn, this branch (n=33) was divided to 2 sub-branches, one of which was formed with 7 strains closest to the collection mass spectra K.pneumoniae RV_BA_03_BLK and K.pneumoniae 37585 PFM. The second sub-branch was formed with 26 strains different from all available in the MALDI Biotyper 3,0 MS collection.
Conclusion: 26 of 35 (74.3 %) isolates of MDR K.pneumoniae with biotypes of 77744372 and 77744272, forming brown MS-peak, prevail in our clinic and present phylogeneticaly close microorganisms other than collection of mass-spectra. Thus, we are dealing with phylogeneticaly new strains to be studied and registered in MALDI Biotyper 3.0 system.