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KLEBSIELLA PNEUMONAIE HARBOURING MULTIPLE CARBAPENEMASES IN CROATIAN HOSPITALS K. pneumoniae isolates often harbor various antibiotic resistance determinants including extended- spectrum β-lactamases (ESBLs), plasmid- mediated AmpC β-lactamases (p-Amp-C) and carbapenemases belonging to class A, B and D. Recently extensively-drug resistant strains harbouring multiple carbapenemases were detected in two hospital centers in Croatia, posing a serious therapeutic challenge for clinicians. In this study we analyzed 11 K. pneumoniae isolates collected in two hospital centers in Croatia, in two periods: 2013 and 2022, with multiple carbapenemase, with regard to antibiotic susceptibility, β-lactamase production, virulence traits and plasmid content. Antibiotic susceptibility to a wide range of antibiotics was determined by broth microdilution method. Double disk synergy (DDST) and combined disk test with clavulanic acid were applied to screen for ESBLs. Hodge and CIM test were used to detect carbapenemase production. PCR was applied to detect genes encoding ESBLs, p-Amp-C and carbapenemases and plasmid incompatibility groups. Five isolates were collected in 2013 whereas five originated from 2022. The isolates demonstrated uniform resistance to amoxicillin/clavulanate, piperacillin/tazobactam, cefuroxime, ceftazidime, cefotaxime, ceftriaxone, cefepime. They exhibited extensively drug- resistant phenotype with susceptibility. DDST demonstrated negative result in all isolates, but combined disk test with clavulanate tested positive in three isolates from the recent period. Modified Hodge and CIM test yielded positive results, indicating production of carbapenemase. The isolates from the first period harboured combination of VIM-1 and NDM-1, whereas the isolates from 2022 possessed genes encoding OXA-48 and VIM-1 or OXA-48 and KPC. Ceftazidime/avibactam tested susceptible in only one strain coharbouring OXA-48 and KPC. The study demonstrated the ability of K. pneumoniae to acquire various resistance determinants, over time. The shift from MBLs in the early 2000-ties to OXA-48 in the last decade was already reported. The presence of MBLs compromises the use to ceftazidime/avibactam. There are many gaps in our understanding of the development of antibiotic resistance in K. pneumoniae and its amazing capacity to accumulate resistance determinants. The species has special biological significance probably associated with specific antibiotic selection pressure, pathogenic fitness, gene mobility and other attributes. |
