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Updated: Oct 13, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Molecular Detection of Virulence Associated Genes in Coagulase Negative Staphylococci Isolated from Blood Culture
Background:
Coagulase-negative staphylococci (CoNS) are one of the most important causes of infections. Unlike Staphylococcus aureus, less is known about their pathogenic mechanisms. In the present study, we aimed to evaluate the presence of virulence genes among 98 CoNS isolated from blood cultures of inpatients.
Methods:
The isolates were identified by MALDI-TOF MS (Bruker Daltonics, Bremen, Germany). PCR was performed to detect 29 virulence factors using specific primers for icaA, icaB, icaC, icaD, icaADB, aap, fbe, aae, sesI, atIE, hla, hlb, hld, gehC, gehD, sea, seb, sec, sed, see, seg, seh, sei, tst, eta, etb, etd, etx, and pvl genes. The VITEK2 system (bio-Merieux, France) and the BD Phoenix™ System (Becton Dickinson, USA) were used for antimicrobial susceptibility testing.
Results:
Staphylococcus epidermidis was found to be the most virulent CoNS species. All isolates were negative for eta, etb, etd, sea, seb, sed, see, seg, sei, and pvl virulence genes. We detected up to 15 virulence genes in a single isolate. The most common gene was icaC (73.5%), followed by icaA (57.1%), icaD (56.1%), aap (55.1%), aae (52.0%), sesl (51.0%), gehC (50.0%), hld (50.0%), hlb (49.0%), fbe (44.9%), atIE (37.8%), icaADB (37.8%), gehD (34.7%), icaB (31.6%), hla (30.6%), etx (2.0%), sec (1.0%), seh (1.0%), and tst (1.0%).
Conclusions:
We determined high rates of genes encoding biofilm formation. Only four isolates did not possess either the ica operon or aap gene. Although we found low rates of toxin-related genes, our data indicates that apart from biofilm formation, the CoNS isolates could express various virulence genes similar to those of Staphylococcus aureus.
Insights
Coagulase-negative staphylococci (CoNS) infections are common, with high rates of biofilm formation genes detected. These CoNS possess diverse virulence genes, similar to Staphylococcus aureus, despite low toxin gene prevalence.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Coagulase-negative staphylococci (CoNS) are significant causes of infections.
- Pathogenic mechanisms of CoNS are less understood compared to Staphylococcus aureus.
- This study investigated virulence genes in CoNS from inpatient blood cultures.
Purpose of the Study:
- To evaluate the presence and prevalence of 29 virulence genes in 98 CoNS isolates.
- To compare the virulence gene profiles of CoNS with Staphylococcus aureus.
- To understand the genetic basis of CoNS pathogenicity.
Main Methods:
- Isolate identification using MALDI-TOF MS.
- Polymerase Chain Reaction (PCR) to detect specific virulence genes (e.g., icaA, aap, hla).
- Antimicrobial susceptibility testing using VITEK2 and BD Phoenix™ systems.
Main Results:
- Staphylococcus epidermidis was the most virulent CoNS species identified.
- High prevalence of biofilm formation genes (icaC, icaA, icaD, aap) was observed.
- Toxin-related genes (eta, etb, sea, etc.) were largely absent, with low detection rates for etx, sec, seh, and tst.
Conclusions:
- CoNS isolates exhibit a high capacity for biofilm formation.
- The presence of various virulence genes suggests potential pathogenicity similar to Staphylococcus aureus.
- Further research is needed to fully elucidate CoNS virulence factors and clinical implications.
