Biofilm production by clinical strains of Acinetobacter baumannii isolated from patients hospitalised in two tertiary care hospitals

Abstract number: R2256

Wroblewska M., Sawicka-Grzelak A., Marchel H., Luczak M., Sivan A.

Objectives: Biofilm poduction by microorganisms is at present increasingly recognised as virulence factor, particularly relevant to opportunistic pathogens, such as Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida spp. However, scarse reports could be found in literature on biofilm formation by clinical strains of Acinetobacter baumannii isolated from hospitalised patients. The aim of the study was to evaluate whether factors such as bacterial genotype, site of isolation, resistance to carbapenems and duration of hospitalisation are related to biofilm formation by clinical strains of A. baumannii.

Methods: In total 34 randomly selected, clinical strains of Acinetobacter baumannii, isolated from patients hospitalised in two tertiary care hospitals (24 strains from hospital A and 10 strains from hospital B), were examined for biofilm formation. They originated from various clinical specimens (blood, catheter tip, urine, wound swabs, bronchial aspirates). Bacteria were cultured according to standard bacteriological techniques. Susceptibility of the isolates to antibacterial agents was tested by a disk-diffusion method (according to CLSI recommendations) and E-tests. The strains were typed retrospectively by RAPD and PFGE analysis. Bacterial biomass in biofilms was determined quantitatively using a spectrophotometer (O.D. 600 nm).

Results: There was a great variability in the ability of the tested strains to produce a biofilm. Analysis of biofilm formation by the studied clinical strains of A. baumannii revealed three groups of strains, regarding their ability to produce a biofilm. However, no relation could be found between the ability of biofilm production and molecular type, carbapenem resistance or site of isolation of the clinical strains of A. baumannii. Interestingly, in two cases an increase in biofilm formation could be detected in A. baumannii isolates cultured from the same patient upon prolonged hospitalisation.

Conclusion: A better understanding of biofilm formation by Acinetobacter and genetic basis for control of this process are required to develop novel strategies for dealing with infections caused by these opportunistic and often multi-drug resistant nosocomial pathogens.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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