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

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. *Corresponding author: Zhamin Liu, School of Life Sciences, Shanghai University, Shanghai, China, Tel: +86-21-66135166/ Fax: +86-21-66135166; E-mail: zhmliu@shu.edu. cn Citation: Liu, Z. , et al. Molecular Identification of Staphylococcus Aureus Isolated from Clinical Samples by Specific PCR Assay Targeting the Signal Transduction Gene Research. (2017) J Pharm Pharmaceutics 4(2): 166171. Molecular Identification of Staphylococcus Aureus Isolated from Clinical Samples by Specific PCR Assay targeting the Signal Transduction gene Zhanmin Liu1*, Zhiwei Zhou1, Yuhao Huang1, Rong Chen1,2 Received date: September 11, 2017 Accepted date: November 1, 2017 Published date: November 7, 2017 DOI: 10.15436/2377-1313.17. 1682 Liu, Z. , et al. gen (clumping factor). Several Staphylococcus species, such as Staphylococcus epidermis (S. epidermis), Staphylococcus haemolyticus (S. haemolyticus), and the coagulase negative species, have been isolated from ewe’s milk and were found to produce one or several staphylococcus enterotoxins[2] and consequently there is a need for methods to specifically discriminate S. aureus from other staphylococci and non-staphylococci as quickly as possible. Conventional identification methods and novel assays based on immunofluorescence probe, DNA microarray, surface enhanced laser desorption and ionization time of flight mass spectrometry, and whole-cell SELEX methods are time-consuming and may yield false-positive or false-negative results, and misclassifications with automated susceptibility testing systems or commercially available latex agglutination kits have been reported recently[4-13]. Many laboratory diagnostic techniques, including those targeting femA, nuc, coa, 16S rRNA, Sa442 and other genes in S. aureus, and rational antibacterial therapies have played an important role in the control of this pathogen[6,14-16]. Especially, detection of S. aureus genes associated with antibiotic resistance including mecA, aacA-aphD, tetM, erm (A), erm (C), vat (A), vat (B), vat (C) by PCR facilitates the appropriate control of the pathogen[17,18]. However, some false positive or negative cases by previous molecular identification assays are reported[16-19]. Therefore, it is particularly important to establish species-specific detection methods, and some speciesand virulence-specific genes are present and used as specific marker in many bacteria including Listeria innocua, Pasteurella multocida and Streptococcus pyogenes in the existing literature[20,21]. Recent description of the whole genome sequences of S. aureus strains provides the great opportunity to carry out detailed investigation of the molecular mechanisms, virulence and pathogenesis in the microbial genome levels. In addition, the systematic comparison of genomic sequences from different organisms represents a central focus of contemporary genome analysis. Comparative analyses of S. aureus sequences can identify coding and conserved non-coding regions, including regulatory elements and species-marker. Based on the previous strategy, the signal transduction gene, vick is described as the species-specific diagnostic marker for identification of S. aureus[17]. In the present study, we developed a new diagnostic method for rapid identification of S. aureus targeting the vick gene. Materials and Methods Samples A total of 110 strains of S. aureus were studied (Table 1). They comprised five S. aureus reference strains (ATCC29213, 6538, 25923, 12228; American Type Culture Collection, Rockville, Md. and CMCC26001; China Medical Culture Collection Center), and 64 confirmed isolates of S. aureus by biochemical test and other bacteria used as negative controls for the PCR experiments from patient samples isolated in the Laboratory of Microbiology (Peking University Health Science Center, Beiijng, China) were used to determine the PCR in vitro assay specificity and sensitivity. Table 1: List of bacteria strains examined in the study. Species Strain code Staphylococcus aureus ATCC25923 human ATCC 6538 human ATCC29213 human CMCC 26001 human 05I-043 human 05C-054 clinic 05C-256 clinic 05A-176 clinic 05A-005 clinic 05A-075 clinic 05C-280 clinic 05Q-132 clinic 05N-119 clinic 05L-189 clinic