Two strains of
Staphylococcus
isolated from urine and sputum samples were
compared with a laboratory strain of
Staphylococcus. Since all three grew on the
same media specific for
S. aureus, they were studied for their relatedness by morphological,
biochemical and molecular characterization. Variation in properties
among the isolates pointed towards their different identity which was confirmed
through 16S rRNA gene sequence based phylogenetic analysis. The isolate A from
urine was found to be closely related to
S. haemolyticus, while isolate P from sputum
was
S. aureus and isolate S from NICED culture collection was closest to
S. epidermidis.
Thus the Hicrome aureus agar (Himedia M1468) was not specific for the
species
S. aureus and could only screen at genus level. The antibiotic profile of the
strains was evaluated using a spectrum of 18 antibiotics. The lecithinase activity
was retained only in freshly isolated strains and totally ceased in subsequent subculturing.
