Antimicrobial resistance in coagulase-negative staphylococci

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Coagulase-negative staphylococci (CoNS) are significant hospital-acquired pathogens.
• Antimicrobial resistance patterns in CoNS vary by species and patient population.
• Understanding resistance is crucial for effective treatment of CoNS infections.

Purpose of the Study:

• To investigate antimicrobial resistance patterns in CoNS isolated from hospitalized patients.
• To compare resistance prevalence and levels between Staphylococcus epidermidis and Staphylococcus haemolyticus.
• To assess cross-resistance profiles of methicillin-resistant CoNS.

Main Methods:

• Antimicrobial susceptibility testing of 193 CoNS strains.
• Comparison of resistance rates in strains from patients with malignant disease versus other sources.
• Determination of minimum inhibitory concentrations (MICs) for key antibiotics.

Main Results:

• CoNS from cancer patients showed higher resistance to sulphonamide, trimethoprim, gentamicin, and methicillin.
• Staphylococcus haemolyticus exhibited significantly higher methicillin resistance (81%) than Staphylococcus epidermidis (17%), with higher MICs.
• Methicillin-resistant S. haemolyticus displayed broader beta-lactam cross-resistance compared to methicillin-resistant S. epidermidis.

Conclusions:

• Patient malignancy is associated with increased CoNS resistance to several antimicrobial agents.
• Staphylococcus haemolyticus is a more significant reservoir of methicillin resistance than S. epidermidis.
• Heterogeneous methicillin resistance was observed in both species; netilmicin, amikacin, rifampicin, vancomycin, and teicoplanin showed high in vitro activity.