Molecular identification of Staphylococcus aureus isolated from clinical samples by specific PCR assay targeting the signal transduction gene

Abstract

Staphylococcus aureus (S. aureus) is a common, Gram-positive species that is pathogenic in both human and animals. Rapid and direct identification of this bacterium specifically from clinical specimens would be useful in improving the diagnosis of S. aureus infections in the clinical microbiology laboratory. Although, some molecular identification assays are reported, some false-positive cases are described; it is an urgent need to develop a specific diagnostic method. Currently, the sensitivity and specificity of polymerase chain reaction targeting a signal transduction gene (vick) for the diagnosis of S. aureus isolates in clinical samples was developed. The assay is sensitive enough to detect 5500 copies of a cloned fragment of the S. aureus vick gene. This PCR assay can be used for rapid clinical diagnosis of S. aureus infection and detection of the pathogen in food samples.

<i>vicK</i> Gene as Potential Identification Marker for <i>Staphylococcus aureus</i>

“…Following PCR amplification of HSNZ isolates, the vicK gene fragment has been successfully detected in 98% of S. aureus ( Figure 1, Table 4). This correlates well with previous findings demonstrating high sensitivity and specificity of PCR targeting vicK [31] [32]. It was also evident that vicK was undetectable in other staphylococci (S. epidermidis, S. (Table 4).…”

“…Although this method was rapid and easy to perform, the resulted DNA varies among samples [47]. The true limit of detecting vicK by PCR was reported above 5500 copies of plasmid DNA [31], thus the efficiency of harvesting DNA target and the amount of DNA yield can limit the sensitivity of PCR assay. We believe the use of appropriate DNA extraction protocols incorporating efficient cell lysis and purification steps may greatly improve the quality of harvested DNA.…”

“…Polymorphisms however occur in some of these genes which limit their use as a reliable identification marker for S. aureus [29] [30]. PCR targeting a signal transduction gene, vicK has been recently described as highly specific and sensitive of detecting a low copy genetic material of S. aureus [31] [32]. vicK encodes the bacterial two-component signal transduction system (TCS) that senses and responds towards the environmental stimuli especially when invading the host [32].…”