Staphylococcal Disease

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). Laboratory studies used in the diagnosis generally include culture and serum antibody testing.

Tabs Content

Clinical Overview

Diagnosis

Indications for Testing

Pustular disease
Abscess, cellulitis

Laboratory Testing

Culture
- Superficial disease – culture of wound or affected area
  - Recommend incision and drainage of all abscesses for wound culture
  - Further testing by polymerase chain reaction (PCR) for the mecA/mecC genes 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

Soft-tissue and skin infections
- Streptococcal infection
- Gram-negative infection
Deep infections– clostridial infection
Pneumonia
- Viral – hantavirus, influenza virus, other respiratory viruses
- Other bacterial – Haemophilus influenzae, Chlamydophila pneumoniae, Mycoplasma pneumoniae
- Fungal – Pneumocystis jirovecii
- Mycobacterium tuberculosis
Gastroenteritis
- Bacterial
- Viral
- Parasitic
Meningitis/encephalitis
- Other bacterial
- Viral
- Fungal
Osteomyelitis
Malignancy
- Ewing sarcoma
- Sarcomas

Background

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
- Immune deficiency
- Diabetes mellitus
- Hospitalization
- Indwelling catheters
- Intravenous drug use (IVDU)
- Primary viral exanthem (eg, varicella-zoster)
- Alcohol abuse
- Local trauma, lymphedema
- Colonization
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
- Pneumonia/empyema
- Septic thrombophlebitis/pulmonary emboli
- Gastroenteritis – food poisoning, rapid onset vomiting, and diarrhea
- Meningitis/brain abscesses/vertebral abscesses
- Toxic shock syndrome

ARUP Lab Tests

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

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification

Recommended Use

Detect presence of bacteria in blood

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 susceptibility 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 the mecA gene may be appropriate and will be performed in order to interpret the results for beta-lactam agents

For mecA gene testing, refer to the antimicrobial susceptibility test for mecA gene by polymerase chain reaction (PCR)

Selective reporting by organism and source

Antimicrobial Susceptibility - mecA/mecC Genes by PCR 0060211
Method: Qualitative Polymerase Chain Reaction

Recommended Use

Gold standard for detecting oxacillin/nafcillin resistance in Staphylococcus species

Determine presence of the mecA/mecC genes that confer resistance to nearly all beta-lactam antibiotics

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

For detection of colonization, order Staphylococcus surveillance culture

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

Medical Experts

Delgado, Julio, MD, MS, Chief Medical Officer; Director of Laboratories; Chief, Division of Clinical Pathology at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

Fisher, Mark A., PhD, D(ABMM), Medical Director, Bacteriology, and Special Microbiology, Antimicrobial Susceptibility Testing, at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

References

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

Resources from the ARUP Institute for Clinical and Experimental Pathology®

Denys GA, Collazo-Velez V, Young S, Daly JA, Couturier MR, Faron ML, Buchan BW, Ledeboer N. Multicenter Evaluation of the Portrait Staph ID/R Blood Culture Panel for Rapid Identification of Staphylococci and Detection of the Gene. J Clin Microbiol. 2017; 55(4): 1140-1146. PubMed

Educational Videos

Last Update: July 2018

Staphylococcal Disease

Diagnosis

Indications for Testing

Laboratory Testing

Differential Diagnosis

Background

Epidemiology

Organism

Risk Factors

Clinical Presentation

ARUP Lab Tests

Medical Experts

References

General References

Resources from the ARUP Institute for Clinical and Experimental Pathology®

ARUP Laboratories

ARUP Websites

ARUP Consult


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Staphylococcal Disease

Diagnosis

Indications for Testing

Laboratory Testing

Differential Diagnosis

Background

Epidemiology

Organism

Risk Factors

Clinical Presentation

ARUP Lab Tests

Medical Experts

References

General References

Resources from the ARUP Institute for Clinical and Experimental Pathology®

ARUP Laboratories

ARUP Websites

ARUP Consult