Multidrug resistance of Klebsiella pneumoniae isolates in a teaching hospital

Abstract number: P665

Vamvacopoulou S., Petinaki E., Bartzavali C., Damani A., Spiliopoulou I., Anastassiou E.D., Christofidou M.

Objective: Klebsiella pneumoniae is emerging as an important nosocomial pathogen due to rapidly increasing resistance to all currently available antibiotics. The aim of this study was to define the susceptibility profile of multidrug resistant (MDR) K. pneumoniae nosocomial isolates to antibiotics, including tigecycline (TIG), during the last three years in Patras University Hospital.

Methods: From September 2005 to October 2008, a total of 216 K. pneumoniae isolates were collected from inpatients hospitalised in ICU (125), in Internal Medicine units (48) and in Surgical Wards (43), one isolate per patient. Isolates were recovered from cultures of clinically significant specimens (102 blood, 76 pus, 24 urine and 14 BAL). Identification was performed by biochemical tests. Antimicrobial susceptibility was carried out by disk diffusion method, according to CLSI criteria, for amoxicillin-clavulanic acid (AMC), cefoxitin (FOX), ceftriaxone (CRO), ceftazidime (CAZ), imipenem (IMP), aztreonam (AZT), gentamicin (GM), netilmicin (NET), amikacin (AN), ciprofloxacin (CIP) and by E-Test strips (AB Biodisk) for TIG. MIC breakpoint of susceptibility to TIG is equal or less than 2 microg/mL. IMP-resistant isolates were examined by E-Test (AB Biodisk) for detection of metallo-beta-lactamases (MBL). In addition the genes encoding MBL (vim, imp) were detected by PCR following by sequencing.

Results: Resistance rate to lactams was as high as 99%, 94%, 100%, 97%, 94% and 79% to AMC, FOX, CRO, CAZ, AZT and IMP, respectively, 87% to AN and CIP, and 91% to NET and 61% to GM. Among 216 MDR isolates, 49% were resistant to all aforementioned antibiotics. Among IMP-resistant strains, 150 (88%) were MBL (+) according to E-Test results, whereas, in 164 (96%) were found to carry the vim-1 gene. Among MDR isolates 90% were susceptible to TIG (MIC 0.25–2). On beginning the study, 5% of 28 MDR isolates were intermediately sensitive to TIG (MIC 3), 7% of 77 the next year and 12% of 111 on 2008. Two resistant strains to TIG with MIC 19 were found during the last month of the study.

Conclusions: A total of 107 (49%) MDR K. pneumoniae were resistant to all commonly used antimicrobials. The presence of vim-1 gene (96%) in MDR isolates make IMP not useful in empiric therapy. The only active agent towards such strains remains TIG (90%), although 9% were intermediately sensitive isolates according to our results. However TIG must cautiously be used, since resistant strains have already emerged.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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