Rapid identification of Staphylococcus aureus by using lysostaphin sensitivity

Area of Science:

• Microbiology
• Clinical Diagnostics

Background:

• Accurate differentiation of Staphylococcus aureus is crucial for effective patient treatment.
• Rapid diagnostic methods are needed to expedite identification in clinical microbiology.

Purpose of the Study:

• To evaluate lysostaphin sensitivity as a rapid screening test for differentiating Staphylococcus aureus from other staphylococci and micrococci.
• To assess the utility of lysostaphin in both pure cultures and clinical specimens.

Main Methods:

• Overnight cultures of bacterial strains were exposed to lysostaphin (2 µg/ml) at 37°C for 30 minutes.
• Gram stains were performed before and after lysostaphin treatment to assess bacterial lysis.
• Prospective analysis of 100 blood or broth cultures identified as gram-positive cocci.

Main Results:

• Lysostaphin demonstrated high sensitivity, with 106 of 108 Staphylococcus aureus strains showing >90% lysis.
• All 60 non-S. aureus staphylococci strains tested were negative (no significant lysis).
• Prospective testing correctly identified all 33 S. aureus positive cultures and all 67 negative cultures.

Conclusions:

• Lysostaphin sensitivity is a reliable and rapid method for differentiating Staphylococcus aureus.
• This test can be effectively used with both pure cultures and clinical samples, including blood cultures.
• Lysostaphin offers a valuable tool for clinical microbiology laboratories to improve diagnostic speed and accuracy.