Pacemaker-associated infection caused by ST81/SCCmec IV methicillin-resistant, vancomycin-intermediate Staphylococcus...

Area of Science:

• Infectious Diseases
• Microbiology
• Genetics

Background:

• Pacemaker-associated infections pose significant clinical challenges.
• Emergence of antibiotic-resistant bacteria, like vancomycin-intermediate Staphylococcus aureus (VI-MRSA), complicates treatment.
• Methicillin-resistant S. aureus (MRSA) strains with specific genetic profiles are of growing concern.

Purpose of the Study:

• To report a case of pacemaker-associated septicaemia caused by a unique VI-MRSA strain.
• To characterize the genetic makeup and antibiotic susceptibility of the isolated S. aureus.
• To highlight successful therapeutic strategies for such infections.

Main Methods:

• Isolation and identification of Staphylococcus aureus from blood cultures.
• Antimicrobial susceptibility testing, including vancomycin and daptomycin.
• Molecular typing, including SCCmec, spa, and coa typing.
• Detection of toxin and resistance genes using PCR.

Main Results:

• A 76-year-old Japanese man developed pacemaker-associated infection with fever and skin lesions.
• Vancomycin-intermediate S. aureus (MIC 4 μg/mL), with reduced daptomycin susceptibility, was isolated.
• The isolate was identified as MRSA (SCCmec IV, ST81, coa VIIa, spa t7044) carrying blaZ, aac(6')-aph(2″), and enterotoxin genes (sea, seb, sek, sel, selx, selw).

Conclusions:

• Sequence type 81/SCCmec IV VI-MRSA can cause severe infections like pacemaker-associated septicaemia.
• Combination therapy with daptomycin, minocycline, and sulfamethoxazole/trimethoprim proved effective.
• This case underscores the importance of vigilant monitoring and tailored treatment for antibiotic-resistant S. aureus infections.