Staphylococcus lugdunensis

Bacteria

Staph lugdunensis is a coagulase-negative Staphylococcus (CoNS) capable of causing aggressive diseases like Staph aureus.

• It is a Gram-positive cocci in cluster formation, which produces a non-pigmented/ yellow/ golden colony and could be beta-haemolytic on blood agar. It tends to show colony polymorphism.
• It has a characteristic odour (hypochlorite bleach-like smell) similar to Eikenella. (Note: smelling/wafting the bacteria on the plate in the laboratory is NOT recommended)
• It is catalase-positive, coagulase neg., non-motile, facultative anaerobe.
• Up to 65% of isolates may produce a clamping factor (bound Coagulase), giving a positive result in the slide coagulase test.
• Use tube Coagulase, which tests for free Coagulase, to differentiate Staph aureus (tube coagulase +ve) from Staph lugdunensis )tube coagulase-negative).
• Identification can be done using MALDI-ToF.

Staph lugdunensis tends to be more susceptible to antibiotics compared to other CoNS.

Vancomycin tolerance – can be present, i.e. the ability of bacteria to survive in the presence of an antibiotic, even if MIC testing has deemed that it should be susceptible. Check MBC: MIC ratio (more likely if >32).

Coagulase-negative Staphylococcus that gives positive results in slide coagulase test – S. lugdunensis, S. schleiferi, and S. sciuri
Coagulase-negative Staphylococcus that gives a positive result in the tube-coagulase test – S. pseudointermedius, S. intermedius, S. hyicus, S. delphini, S. schleiferi and S. lutrae.

Pathogenesis

• Biofilm – Protein biofilm (unlike other bacteria – polysaccharide). Biofilm makes the bacteria highly resistant to antibiotics. Biofilm formation decreases in the presence of linezolid and tetracycline.
• Moxifloxacin is the only abx which is active against biofilm S lugdunensis.
• Other virulence factors:
  – Adherence factors, vWF and fibronectin-binding protein (endothelial adhesion)
  – Delta toxins like haemolytic peptide, DNAse, Lipase
• Similar virulence factors are noted in S schleiferi as well, but it mostly causes animal disease.

Clinical feature

• Skin and soft tissue infection– Staph lugdunensis tend to colonize below the waist, esp. perineum. Infection can occur secondary to an invasive procedure in the groin. Infective endocarditis (IE) has been reported to be associated with prostate cancer/ perineal procedures or lesion.
  The most common soft tissue infection above the waist is breast abscess.
• Endocarditis: Community-acquired, usually involving the native valve. It is an aggressive disease with a high rate of complication and mortality (>40%)—complications – heart failure, peri-annuler abscess, and embolism.
  Prosthetic valve endocarditis – late onset, with a high rate of peri-annuler abscess (>60%).
• Bacteraemia: Often associated with foreign bodies, healthcare-associated. The prognosis is good if it is not associated with IE.
• Other infections – prosthetic device (joint/shunt) infection, arthritis, OM, psoas abscess, UTI, peritonitis.

Treatment

• Treatment should be guided by susceptibility testing.
• Flucloxacillin can be used.
• SSTI – treat for 1-2 weeks, non-IE bacteraemia – 1 week, endocarditis – follow BSAC guideline.