Background
Biofilm formation on indwelling devices is one of the most important mechanisms playing a role in device-related urinary tract infections caused by Proteus mirabilis. Increasing antibiotic resistance of microorganisms has raised questions concerning the relationship between biofilm formation and drug resistance.
Objectives
To determine clinical prevalence, antibiotic resistance of, and biofilm formation by P. mirabilis strains.
Methods
We studied the susceptibilities of various P. mirabilis strains isolated from different clinical materials by a disc-diffusion method. Biofilm formation was determined by a crystal violet binding assay.
Results
Two (13%) of 15 P. mirabilis strains were found to be strong biofilm formers (SBF). Both SBF P. mirabilis strains were isolated from urine samples from children less than 15 years old in a pediatric emergency unit. Cefixime, cefazolin, ceftriaxone, amikacin, and piperacillin/tazobactam were the most effective antibiotics against 15 P. mirabilis strains (100%), whereas SBF P. mirabilis strains were multidrug resistant or (resistant to 5 different antimicrobial classes). Both of the SBF P. mirabilis strains, but neither of the weak biofilm forming P. mirabilis strains were resistant to ampicillin and ceftazidime among β-lactam antibiotics, or tobramycin and gentamicin among aminoglycoside antibiotics used in the present study.
Conclusions
Children comprise the only patients infected with SBF P. mirabilis strains and both SBF P. mirabilis strains displayed high antimicrobial resistance in our setting.
