Staphylococcal Disease

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Pustular disease; abscess, cellulitis
  • Bacteremia associated with deep-seated staphylococcal infection may present a puzzling picture since the focus of infection may not be readily apparent

Laboratory Testing

  • Culture
    • Superficial disease – culture of wound or affected area; recommend incision and drainage of all abscesses for wound culture
      • Further testing by PCR for mecA to rule out resistant staphylococci
    • Deep-seated infections – gram stain and culture of the organism from appropriate clinical specimens
  • Serum antibody testing
    • Prolonged exposure to staphylococci during deep-seated infection can result in elevated antibodies to staphylococcal ribitol teichoic acid (RTA)
      • High antibody levels (≥1:4) against staphylococcal RTA in patients with staphylococcal bacteremia may indicate staphylococcal endocarditis or complicated staphylococcal bacteremia

Differential Diagnosis

Staphylococcus aureus bacteria are gram-positive cocci that cause diseases of varying severity, from skin and soft-tissue infections (eg, folliculitis, impetigo, cellulitis, abscesses) to deep-seated infections (eg, endocarditis, osteomyelitis).

Epidemiology

  • Incidence – 28-35/100,000
  • Transmission
    • Portal of entry for superficial infections is frequently unknown but may be from a surface abrasion
    • Portal of entry for deep infections includes surgical sites or indwelling catheters

Organism

  • Gram-positive cocci; coagulase positive
  • May acquire drug resistance, including resistance to nearly all beta-lactam agents
    • Known as methicillin-resistant Staphylococcus aureus (MRSA)

Risk Factors

  • Methicillin-sensitive Staphylococcus
  • MRSA
    • Antibiotics in past month (odds ratio 2.4)
    • Abscess (odds ratio 1.8)
    • Reported spider bite (odds ratio 2.8)
    • History of MRSA (odds ratio 3.3)
    • Close contact with MRSA patient (odds ratio 3.4)
    • Snorting or smoking illegal drugs (odds ratio 2.9)
    • Incarceration ≤12 months (odds ratio 2.8)

Clinical Presentation

  • Superficial skin infections
    • Folliculitis
    • Impetigo
    • Cellulitis (more commonly caused by beta-hemolytic Streptococcus)
      • Infection penetrates the subcutaneous tissue layer
        • Erythema and warmth; swelling and tenderness of affected area
    • Staphylococcal scalded skin syndrome
  • Soft-tissue infections
    • Abscess
      • >50% are caused by Staphylococcus
      • Includes furuncles and carbuncles
      • Area of fluctuance and erythema demarcate the abscess
    • Necrotizing fasciitis
      • Type 1 frequently caused by Staphylococcus
      • Rapid progression of local symptoms, including systemic symptoms (eg, fever)
        • Pain out of proportion to apparent involvement
        • Marked edema
  • Deep infections
    • Endocarditis – associated with native and prosthetic valves, indwelling catheters, or IVDU
    • Osteomyelitis – frequently associated with underlying immune deficiency
    • Deep tissue and muscle abscesses
    • Septic arthritis – associated with implanted joints, rheumatoid arthritis, immunocompromised state
  • Other infections

Treatment

  • Superficial – frequently cured with topical or systemic antibiotic therapy and abscess drainage
  • Deep – involves tissue debridement/abscess drainage and systemic antibiotic therapy
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Staphylococcus Surveillance Culture 0060124
Method: Culture/Identification

Recommended Use 

Identify Staphylococcus aureus colonization

Follow-up 

Decolonization has variable success in preventing subsequent infections

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification

Recommended Use 

Detect presence of bacteria in blood

Blood samples from two different anatomic sites required

Limitations 

Testing is limited to the University of Utah Health Sciences Center only

Wound Culture and Gram Stain 0060132
Method: Stain/Culture/Identification

Recommended Use 

Identify bacteria in wounds

Anaerobe culture is recommended for body fluids, tissue, and deep wound/surgical cultures; refer to anaerobe culture and gram stain

Limitations 

Anaerobe culture is NOT included with this order

Antimicrobial Susceptibility - Staphylococcus 0060707
Method: Automated Broth Microdilution

Recommended Use 

Determine in-vitro susceptiliity to antimicrobial agents for Staphylococcus spp

The following agents are tested – clindamycin, daptomycin, erythromycin, gentamicin, levofloxacin, linezolid, nitrofurantoin, oxacillin, penicillin, quinupristin/dalfopristin, rifampin, tetracycline, trimethoprim/sulfamethoxazole, and vancomycin

For serious infections with coagulase-negative staphylococci, testing for the presence of mecA may be appropriate and will be performed in order to interpret the results for β-lactam agents

Selective reporting based on source

Antimicrobial Susceptibility - mecA Gene by PCR 0060211
Method: Qualitative Polymerase Chain Reaction

Recommended Use 

Gold standard for detecting oxacillin/nafcillin resistance in Staphylococcus species

Determines presence of mecA gene that confers resistance to nearly all beta-lactam antibiotics

Refer to antimicrobial susceptibility (Staphylococcus) test for susceptibility panel testing for Staphylococcus spp

Limitations 

Negative mecA PCR does not exclude oxacillin resistance

Teichoic Acid Antibodies 0050775
Method: Semi-Quantitative Immunodiffusion

Recommended Use 

Aid in diagnosis of staphylococcal disease

Limitations 

Negative result does not exclude staphylococcal disease

Positive antibody assay does not denote protection from subsequent infection

General References

Corey R. Staphylococcus aureus bloodstream infections: definitions and treatment. Clin Infect Dis. 2009; 48 Suppl 4: S254-9. PubMed

Gorwitz RJ. A review of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections. Pediatr Infect Dis J. 2008; 27(1): 1-7. PubMed

Luteijn JM, Hubben GA, Pechlivanoglou P, Bonten MJ, Postma MJ. Diagnostic accuracy of culture-based and PCR-based detection tests for methicillin-resistant Staphylococcus aureus: a meta-analysis. Clin Microbiol Infect. 2011; 17(2): 146-54. PubMed

Miller LG, Kaplan SL. Staphylococcus aureus: a community pathogen. Infect Dis Clin North Am. 2009; 23(1): 35-52. PubMed

Naber CK. Staphylococcus aureus bacteremia: epidemiology, pathophysiology, and management strategies. Clin Infect Dis. 2009; 48 Suppl 4: S231-7. PubMed

Peterson LR. Molecular laboratory tests for the diagnosis of respiratory tract infection due to Staphylococcus aureus. Clin Infect Dis. 2011; 52 Suppl 4: S361-6. PubMed

Rehm SJ. Staphylococcus aureus: the new adventures of a legendary pathogen. Cleve Clin J Med. 2008; 75(3): 177-80, 183-6, 190-2. PubMed

Rogers KL, Fey PD, Rupp ME. Coagulase-negative staphylococcal infections. Infect Dis Clin North Am. 2009; 23(1): 73-98. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Shutt CK, Pounder JI, Page SR, Schaecher BJ, Woods GL. Clinical evaluation of the DiversiLab microbial typing system using repetitive-sequence-based PCR for characterization of Staphylococcus aureus strains. J Clin Microbiol. 2005; 43(3): 1187-92. PubMed

Williams D, Bloebaum R, Petti CA. Characterization of Staphylococcus aureus strains in a rabbit model of osseointegrated pin infections. J Biomed Mater Res A. 2008; 85(2): 366-70. PubMed

Medical Reviewers

Delgado, Julio, MD, MS, Head, Histocompatibility and Immunogenetics; Section Chief, Immunology Division at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

Fisher, Mark A., PhD, D(ABMM), Medical Director, Bacteriology and Antimicrobials at ARUP Laboratories; Assistant Professor of Clinical Pathology, University of Utah

Last Update: September 2016

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