Objectives: Nowadays, due to the biofilm formation among coagulase-negative staphylococci
(CoNS), acquisition of antibiotic resistance and virulence genes could be noted. These organisms
resemble other staphylococcus that harbor mecA gene, which encodes methicillin resistance
but the diversity in CoNS is higher than other species. Based on increasing antibiotic resistance
in Staphylococcus haemolyticus, analyzing of phenotypic and genotypic biofilm formation,
antibiotic resistance and genes involved in this process, SCCmec and ACME typing were the aims
of the current study.
Methods: 256 clinical CoNS isolates were collected, out of which 49 isolates were identified as S.
haemolyticus. For evaluation the antibiotic resistance patterns, disk agar diffusion method was applied,
and also biofilm assay was carried out among methicillin resistant S. haemolyticus and
SCCmec and ACME typing.
Results: The results of antibiotic susceptibility indicated that the highest resistance was found in
cotrimoxazole and erythromycin (86.6%) and the frequency of blaA (96.5%) and msrA (79.3%)
genes was much higher than others. Among MRSH isolates 58.6 % showed a weak biofilm phenotype
and 41.4% demonstrated a moderate biofilm density. Also, among the biofilm correlated
genes, IS 256 (79.31%) was the most frequent. The SCCmec typing of MRSH isolates indicated
that the type V was dominant.
Conclusion: Our findings indicated that the correlation between high rates of existence Is 256
gene and high prevalence of weak biofilm phenotype was among MRSH isolates. The current
study revealed that multiple antibiotic resistance existed in S. haemolyticus isolates that is a warning
for public health.
Keywords: Staphylococcus haemolyticus, biofim, SCCmec typing, CoNS,
antibiotic resistance, MRSH.
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