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Evaluation of modified
Congo red agar for detection of biofilm produced by clinical
isolates of methicillin–resistance Staphylococcus aureus
N. S. Mariana1,2, S. A.
Salman1*, V. Neela1 and S. Zamberi1
1Department
of Medical Microbiology and Parasitology, Faculty of
Medicine and Health Science,
2Laboratory
of Marine Science and Aquaculture, Institute of Bioscience,
Universiti Putra Malaysa, 43400Serdang, Selangor
*Corresponding author. E-mail:
salmanatshan@yahoo.com
Accepted
29 May, 2009 |
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Methicillin
resistance Staphylococcus aureus (MRSA) notoriety is
not limited to nosocomial or community acquired infection
but is so much the cause of biofilm related infection. Use
of highly selective or differential medium, published Congo
Red Agar (PCRA) has important shortcomings such as
variations in black pigment formation while the
intracellular adhesion locus (ica) gene required for biofilm
production received equivocal outcomes since contradictory
results. The evaluation of modified Congo Red Agar (MCRA)
was conducted based on the characteristics of 100 MRSA
isolated from different clinical samples and controls. All
MRSA isolates showed presence of icaA and icaD genes by the
PCR method and then formed intense black pigmented colonies
on the Modified Congo Red Agar with increased times in
contrast growth of 78% MRSA strains were exhibited black
pigmentation on the published CRA but pigmentation decreased
with time. The phenotypic coloration on agar improved upon
modification of agar ingredients. The reduction in the
concentration of several agar constituents resulted in
permanent formation of intense black pigment in isolates
with ica A and D genes, without any decreased in
pigmentation over time. The agar constituent modification
allowed stability of black pigment formation and also
reduced agar preparation cost.
Key
words:
MRSA, biofilm, icaA and icaD genes, polymerase chain
reaction (PCR), modified CRA, unmodified CRA. |
