TITLE:
Comparison of MIC with MBEC Assay for in Vitro Antimicrobial Susceptibility Testing in Biofilm Forming Clinical Bacterial Isolates
AUTHORS:
Summaiya Mulla, Ambuj Kumar, Sangita Rajdev
KEYWORDS:
Bacterial Biofilms, Antibiotics, MIC, MBEC
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.2,
February
18,
2016
ABSTRACT: Context: MIC results can be misleading for treatment
of biofilm associated. The Minimum Biofilm Eradication Concentration (MBEC)
measures the determination to be made for a biofilm susceptibility to antibiotics. Aims: Assessment of biofilm production
and comparison of the MIC and MBEC assays evaluate differences in the
antibiotic sensitivity patterns of different clinical bacterial isolates from
patients implanted with medical devices. Settings
and Design: Random sampling with experimental study at tertiary care
institute. Methods and Material: The study was carried out
during January 2014 to March 2014 on 50 positive bacteriological cultures of
medical devices which were inserted in hospitalized patients. Biofilm forming
strains were identified by tissue culture plate method & tube method.
Biofilm-producing and non-biofilm forming reference strains were used as
controls. Assay has been developed for the use with flat bottom, 96-well microtiter plates. Sterile autoclaved PCR tubes
were used as pegs which provided surface for
the biofilm formation. Amikacin, ciprofloxacin, trimethoprim-sulfamethoxazole, vancomycin,
cefoperazone/ sulbactam, gentamycin
were tested for MIC and MBEC assay. Statistical
Analysis Used: Results will be discussed in the form of percentages. Results: Colonization by Klebsiella pneumoniae, Acinetobacter baumanni and Pseudomonas aeruginosa was prevalent bacterial isolates in medical
devices. MBEC was higher for all the antibiotics as compared to MIC except
amikacin MBEC for Pseudomonas was the same as MIC. Conclusions: Device associated bacterial biofilms are the major source of infections in patients of
critical care setup. MIC misleads physician for organism’s drug susceptibility
testing,
which results in therapeutic failure. MBEC can guide
regarding choice and proper dosing of antibiotics to be given. That’s why major
studies for similar testing should be done with clinical evaluation.