Resistance Status and Evolution Trends of Klebsiella pneumoniae Isolates in a University Hospital in Greece: Ineffectiveness of Carbapenems and Increasing Resistance to Colistin

Background: Due to its increased non-susceptibility rates, Klebsiella pneumoniae has emerged as one of the most problematic pathogens. Methods: The level of resistance to 25 antimicrobials of K. pneumoniae isolates from a teaching hospital in Greece and the evolution trends during 2 decades were examined. Results: A statistically significant increase in non-susceptibility rates was found for almost all antimicrobials examined. During 2008, the isolates presented non-susceptibility rates to aminoglycosides >50% and to quinolones >60%. Nowadays, 1 out of 10 isolates is non-susceptible to colistin. Moreover, the isolates non-susceptible to imipenem were almost doubled between 2007 (29%) and 2008 (50%). Among the imipenem-resistant isolates, 1 out of 4 was also resistant to colistin. Conclusion: The effectiveness of carbapenems has been compromised and the increase in resistance to colistin is rapid and steep.