Problems with the laboratory identification and evaluation of coagulase-negative staphylococci

Area of Science:

• Medical Microbiology
• Clinical Diagnostics
• Infectious Diseases

Background:

• Coagulase-negative staphylococci (CoNS) are frequently isolated from clinical specimens.
• Understanding the prevalence and significance of different CoNS species is crucial for patient care.

Purpose of the Study:

• To identify and characterize CoNS isolates from routine clinical specimens.
• To assess the pathological significance and antibiotic resistance patterns of these CoNS.

Main Methods:

• Prospective recovery of 796 CoNS isolates over 105 days from various specimen types.
• Presumptive identification of 315 isolates, including Staphylococcus epidermidis, S. capitis, and S. saprophyticus group.
• Assessment of pathological significance using laboratory criteria and analysis of antibiograms.

Main Results:

• Staphylococcus epidermidis was the most common species (55.6%).
• Significant proportions of CoNS from catheter tips (44.8%), urines (25.9%), and blood cultures (4.5%) were deemed potentially significant.
• High rates of antibiotic resistance were observed, including penicillin (63.2%), methicillin (22.6%), and gentamicin (27.5%), with multiple resistance being common.
• Methicillin resistance was prevalent in S. saprophyticus group strains.

Conclusions:

• CoNS are prevalent in clinical settings, with S. epidermidis being the most common.
• A notable percentage of CoNS isolates, especially from invasive sites, are potentially pathogenic.
• Widespread antibiotic resistance, including methicillin and gentamicin resistance, poses a significant challenge in managing CoNS infections.