title: Acinetobacter baumannii in Southern Croatia: clonal lineages, biofilm formation, and resistance patterns.
abstract: BACKGROUND
  Acinetobacter baumannii is one of the most prevalent causes of severe hospital-acquired infections and is responsible for the dramatic increase in carbapenem resistance in Croatia in the last 5 years. Such data have encouraged multicenter research focused on the organism's ability to form biofilm, susceptibility to antibiotics, and particular genotype lineage.
  
  
  METHODS
  Biofilm formation in 109 unrelated clinical isolates of A. baumannii recovered in six cities of Southern Croatia was investigated. Genotyping was performed by pulsed-field gel electrophoresis and antibiotic profile was tested by applying the disc diffusion method and confirmed by determining the minimum inhibitory concentrations. The ability to form biofilm in vitro was determined from overnight cultures of the collected isolates on microtiter plates, after staining with crystal violet, and quantified at 570 nm after solubilization with ethanol. The statistical relevance was calculated in an appropriate program with level of statistical confidence.
  
  
  RESULTS
  There was no significant difference in biofilm formation due to the genotype lineage. Isolates collected from intensive care units (ICUs) and isolated from respiratory samples were more likely to create a biofilm compared with isolates from other departments and other samples. There was a significant difference in the ability to produce biofilm in relation to antibiotic resistance pattern. A large proportion of A. baumannii isolates that were resistant to ampicillin/sulbactam, carbapenems, and amikacin were found to be biofilm-negative. In contrast, isolates susceptible and intermediately susceptible to ampicillin/sulbactam, carbapenems, and amikacin were biofilm producers.
  
  
  CONCLUSIONS
  Clinical isolates of A. baumannii from respiratory samples in ICUs with a particular susceptibility pattern are more prone to form biofilm.
authors.affiliation: a From the Public Health Institute of Split-Dalmatia County , Split , Croatia.|d University of Split School of Medicine , Split , Croatia.
authors.forename: Vanja
authors.initials: V
authors.lastname: Kaliterna
authors.affiliation: b University Hospital Centre Split , Split , Croatia.
authors.forename: Mariano
authors.initials: M
authors.lastname: Kaliterna
authors.affiliation: c Faculty of Science, Division of Biology, University of Zagreb , Zagreb , Croatia.
authors.forename: Jasna
authors.initials: J
authors.lastname: Hrenović
authors.affiliation: a From the Public Health Institute of Split-Dalmatia County , Split , Croatia.
authors.forename: Zvonimir
authors.initials: Z
authors.lastname: Barišić
authors.affiliation: b University Hospital Centre Split , Split , Croatia.|d University of Split School of Medicine , Split , Croatia.
authors.forename: Marija
authors.initials: M
authors.lastname: Tonkić
authors.affiliation: b University Hospital Centre Split , Split , Croatia.|d University of Split School of Medicine , Split , Croatia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Goic-Barisic
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D000583:Amikacin / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D015780:Carbapenems / Q000494:pharmacology; D017523:Croatia; D003428:Cross Infection; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D007362:Intensive Care Units; D008826:Microbial Sensitivity Tests; D009010:Monte Carlo Method; D012137:Respiratory System / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000382:microbiology; D013407:Sulbactam / Q000494:pharmacology; D014556:Urine / Q000382:microbiology; D014947:Wounds and Injuries / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; C035444:sultamicillin; D000667:Ampicillin; D000583:Amikacin; D013407:Sulbactam
keywords: Acinetobacter baumannii; Southern Croatia; biofilm formation; genotyping; resistance to antibiotics