Community-acquired infection caused by small-colony variant of Staphylococcus aureus

Area of Science:

• Microbiology
• Infectious Diseases
• Bacteriology

Background:

• Small colony variants (SCV) are a distinct morphotype of bacteria, including Staphylococcus aureus, often associated with chronic or recurrent infections.
• SCVs typically arise after exposure to antimicrobial agents and possess altered metabolic and virulence characteristics.
• Their unusual colonial morphology and slow growth can lead to misidentification or failure to detect in standard microbiological cultures.

Observation:

• This infectious disease grand round discusses a clinical case involving a SCV of Staphylococcus aureus with an atypical presentation.
• The case highlights the challenges in diagnosing infections caused by SCVs due to their subtle appearance.
• The patient experienced recurrent infections, suggesting a persistent or relapsing underlying condition.

Findings:

• SCVs of Staphylococcus aureus can evade standard diagnostic methods, leading to delayed or incorrect treatment.
• Incomplete incubation periods for clinical specimens, particularly aspirates from abscesses, increase the risk of missing SCV diagnoses.
• Prolonged incubation is essential for the successful isolation and identification of SCVs in patients with recurrent infections.

Implications:

• Failure to identify SCVs can result in prolonged antimicrobial therapy, treatment failures, and persistent patient morbidity.
• Awareness of SCV characteristics and the need for extended incubation protocols are critical for clinicians and microbiologists.
• Improved diagnostic strategies are needed to enhance the detection of SCVs, particularly in the context of recurrent staphylococcal abscesses and other persistent infections.