engleski

Parallel outbreaks of carbapenem-resistant Acinetobacter baumannii in two long-term care facilities in Croatia

Acinetobacter baumannii has become one of the most challenging agents of nosocomial infections in recent years ; its relevance largely depends on a wide antimicrobial resistance, arising from a variety of intrinsic and acquired mechanisms. Of particular concern is resistance to β-lactam antibiotics, particularly carbapenems, which is often associated with the international clones clonal lineages 1-8. Nine A. baumannii isolates with reduced susceptiblity to carbapenems were isolated in Godan nursing home in Zagreb from February to March 2017, and four in April 2018 from Vitasan nursing home in Pula. Antibiotic susceptibilities were determined by broth microdilution. Genes encoding carbapenemhydrolzing oxacillinases, metallo-β- lactamases (MBLs), and ESBLs were investigated by PCR. Genotyping was performed by sequence group determination, PFGE and MLST. The incompatibility group of the plasmids was detected by multiplex PCR. The strains were uniformly resistant to third and fourth generation cephalosporins, carbapenems, piperacillin/tazobactam, gentamicin and ciprofloxacin, but susceptible or intermediate susceptible to ampicillin/sulbactam, and susceptible to colistin. Four strains were found to be positive for blaOXA-23 and the rest for blaOXA-24/40. PCR amplicons from four representative isolates were sequenced and revealed blaOXA-23 (strain 33980), blaOXA-72 (strains 5139-1, 41378 and 545-1) and blaOXA-66 (33980, 5139-1, 41378, and 545) allelic variants. ISAba1 was found upstream of blaOXA- 51 and blaOXA-23 gene. All isolates belonged to SG 1 (IC II). They contained strAB, armA and aac(6‘)-II aminoglycosides resistance genes, sul 1 or sul2 encoding resistance to sulphonamides, and tetB responsible for tetracycline resistance. All tested isolates from each center (eight from Zagreb and three from Pula) clustered by PFGE in one clone. Four strains were positive for group 2 plasmid. Comparison of PFGE patterns of the isolates from this study with those from 2013, originating from the same nursing home, revealed clonal relatednes (>80%). The study demonstrated spread of OXA-24-like positive strains not only in the clinical setting but also in long-term care facilities. The study found high genetic similarity of A. baumannii isolates from two centers located in distant geographic areas and genetic stability of isolates from different time periods.

Acinetobacter baumannii ; carbapenem resistant ; outbreakes ; Croatia

nije evidentirano