Frequency of extended spectrum beta-lactamase producing Klebsiella pneumoniae isolated from blood in Vojvodina, Serbia during 2009 to 2010

The prevalence of extended-spectrum beta-lactamases (ESBL) varies between countries. The aim of this study was to determine the prevalence of ESBL producing Klebsiella pneumoniae originating from blood in the Vojvodina Province, Serbia. The study was conducted at Institute of Public Health of Vojvodina in Novi Sad, Serbia, in a two year period from January 2009 to December 2010. A total of 11894 blood samples from patients admitted to the Center were obtained for culture. Seventy-seven isolates of K. pneumoniae were reported. Antibiotic susceptibility testing and detection of ESBL production were carried out according to Clinical and Laboratory Standards Institute (CLSI) criteria. The ESBL phenotype was detected in 16 (53.3%) and 32 (68.1%) isolates in 2009 and 2010, respectively. Resistance to piperacillin/tazobactam increased from 43.7% in 2009 to 75% in 2010 while for amoxicillin/clavulanic acid decreased from 75 to 71.9% in the same period. Amikacin was more effective than gentamicin. More than 80% of isolates were resistant to cotrimoxazole and ciprofloxacin. All ESBL-producing isolates tested were sensitive to carbapenems. This study shows a very high prevalence of ESBL-producing K. pneumoniae among hospitalized patients with bloodstream infections and suggests that amikacin should be considered as synergistic antibiotic for the treatment of these infections together with other antimicrobial drugs.