Clinical consequences of using PNA-FISH in Staphylococcal bacteraemia

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Antimicrobial Stewardship

Background:

• Rapid identification of pathogens in blood cultures (BCs) is crucial for optimizing patient treatment and antimicrobial use.
• Differentiating Staphylococcus aureus (SA) from coagulase-negative staphylococci (CoNS) in BCs is challenging but essential for appropriate therapy.

Purpose of the Study:

• To evaluate the impact of peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) on differentiating SA from CoNS in positive BCs.
• To assess the effect of PNA-FISH on prescribed antimicrobial therapy and clinician-microbiologist contact frequency.

Main Methods:

• Retrospective review of patients with SA or CoNS in blood cultures during 2011.
• Comparison between patients whose BCs were tested with PNA-FISH and those who were not.
• Analysis of antimicrobial prescriptions and communication logs.

Main Results:

• PNA-FISH use was associated with a significant decrease in clinician-microbiologist contacts for CoNS (0.82 vs. 1.39, p < 0.0001).
• Appropriate antimicrobial therapy for SA bacteremia increased in the PNA-FISH group (98.0% vs. 89.4%, p = 0.025).
• Increased use of dicloxacillin for SA treatment was observed in the PNA-FISH group (29.6% vs. 8.2%, p = 0.0003).

Conclusions:

• PNA-FISH enables faster, more accurate differentiation of SA from CoNS in blood cultures.
• Implementation of PNA-FISH leads to more appropriate, narrower-spectrum antimicrobial therapy for SA bacteremia.
• PNA-FISH reduces unnecessary consultations regarding CoNS, optimizing laboratory and clinical resources.