PATHOGENIC FEATURES AND
THERAPEUTICAL IMPLICATIONS OF BIOFILM
DEVELOPMENT ABILITY IN MICROBIAL
STRAINS ISOLATED FROM RHINOLOGIC
CHRONIC INFECTIONS
ION ANGHEL1,*, MARIANA CARMEN CHIFIRIUC2,*, GEORGIANA
ALINA ANGHEL3*
1University of Medicine and Pharmacy ”Carol Davila”, Bucharest
2University of Bucharest, Faculty of Biology, Microbiology Department
3ENT Clinic, “Coltea” Hospital, Bucharest, Romania
*corresponding authors: ionangheldoc@yahoo.com,
carmen_balotescu@yahoo.com, dr_alina.anghel@yahoo.com
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Abstract:

Recent studies stated that 60% to 85% of all microbial infections involve biofilms, developed on natural tissues or artificial devices which exhibited an additional resistance/tolerance to antimicrobial substances (called phenotypical or behavioural). Whereas much is known about biofilm formation on inert surfaces under laboratory conditions, little is
known about mucosal biofilms. The aim of this study was to investigate by in vitro methods the ability of microbial strains isolated from different pathologies of the rhinosinusal mucosa to adhere and develop
biofilms on different substrata, in order to evaluate the contribution of this pathogenicity feature to the therapeutical difficulties encountered in the management of chronic rhinosinusitis.The study was performed on 31 randomized clinical cases of otorhinologic chronic infections,
operated in the Surgical Clinic of Coltea Hospital of Bucharest, Romania. The specimens were collected intra-operatory and processed by macroscopic evaluation, microscopic examination, susceptibility testing. The isolated bacterial strains were further studied for their adherence
capacity on the cellular substrate represented by HeLa cells and onto inert substrata.
In our study, the ethiological range of microbial strains isolated from rhinologic infections was large, being represented by Gram-negative bacilli (Pseudomonas aeruginosa, Acinetobacter baumanii, Klebsiella pneumoniae, Proteus sp.), Gram-positive cocci, fungi and Actinomyces sp. strains. The majority exhibit wild antibiotic susceptibility patterns although
multiresistance patterns were registered in P. aeruginosa and A. baumanii strains. All tested strains proved the ability to colonize the cellular and inert substratum. The Gram-negative nonfermentative bacilli (P. aeruginosa and A. baumanii), as well as K. pneumoniae exhibited the highest ability to colonize the inert substrate, while P. aeruginosa and the Gram-positive cocci exhibited the highest adherence indexes to the cellular substrate represented by HeLa cells. Our study demonstrated that the bacterial strains isolated from chronic rhinologic infections exhibited the ability to adhere and colonize the cellular and inert substrata. Consecutively they
formed biofilms, leading to chronic, difficult to treat infections, due to the decreased susceptibility of sessile cells to antimicrobial agents compared to their planktonic counterparts.
It is therefore imperative that a standardized antimicrobial susceptibility testing protocol for such microbial strains isolated from biofilms to be implemented, from both a clinical and research standpoint.

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