Naslov
The ability to form biofilm of multicentre collected clinical isolates of Acinetobacter baumannii in southern Croatia as a possible defense mechanism to antibiotics

Autori
Kaliterna, Vanja ; Kaliterna, Mariano ; Hrenović, Jasna ; Tonkić, Marija ; Goić-Barišić, Ivana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
ESCMID Online Lecture Library / - , 2015

Skup
European Congress of Clinical Microbiology and Infectious

Mjesto i datum
Kopenhagen, Danska, 25.04.2015. - 28.04.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
biofilm formation; Acinetobacter baumannii; multicenter study; Croatia

Sažetak
The scope of this multicenter investigation was to determine the ability of biofilm formation in clinical isolates of Acinetobacter baumannii collected from various medical institutions in the south Croatia depending on the origin of tested isolates (departments from which samples are taken and types of clinical samples) and resistance to antibiotics. This study has analyzed in total 80 isolates of A. baumannii collected prospectively in different cities of the south Croatia, during the twomonth monitoring period. Isolates originated from different medical institutions, departments, and types of clinical samples. After isolation of A. baumannii isolates, initial identification was made using commercial tests for the identification of non-fermenting bacteria. Isolates of A. baumannii have confirmed with the presence of an OXA-51 type β-lactamase (specific to A. baumannii), performed by polymerase chain reaction. The susceptibility of isolates to antibiotics was tested by applying a disk diffusion method and by determining the minimum inhibitory concentrations. The ability to form biofilm in vitro was determined from overnight cultures diluted in Luria Bertani medium. Biofilm was stained with 0.5% crystal violet and quantified at 570 nm. The OD (optical density) corresponds to the amount of biofilm formed by bacteria. The interpretation for OD values: non-biofilm-forming (< 0.4), low biofilm-forming (0.4 – 1.0) and strong biofilm-forming (> 1.0). The statistical relevance of differences was conducted in the SPSS 17.0 software (SPSS Inc., USA). The level of the statistical confidence was determined at P<0.05. Out of the total number of 80 isolates, biofilm was not formed by 22 (27.5%) isolates, and 58 (72.5%) isolates were positive for biofilm production (34 showed a low ability to form biofilm, while 24 were strong biofilm producers). Isolates of A. baumannii collected from the intensive care units (38/48) and isolated from clinical respiratory samples (tracheal and bronchial aspirate and bronchoalveolar lavage) (27/33) were more likely to create a biofilm compared to isolates from other departments and other samples (urine, blood culture, wound swab). We have established the significant difference in the ability to form biofilm in tested isolates of A. baumannii with respect to their resistance to ampicillin/sulbactam, imipenem, meropenem and amikacin. The majority of isolates susceptible or intermediate to the above mentioned antibiotics have an ability to form biofilm. Large proportions of isolates resistant to the above mentioned antibiotic do not form biofilm, probably because they have already developed some other type of defense mechanism against antibiotics. A great number of A. baumannii isolates formed biofilm, which was observed more frequently in isolates recovered from ICU and from clinical respiratory samples as well as in those susceptible or intermediate to ampicillin/sulbactam, imipenem, meropenem and amikacin, what might suggest their possible defense mechanism to antibiotics.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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