COMMENTS
For staphylococcal intoxications, see "Toxic shock syndrome," "Staphylococcal scalded skin syndrome," and "Staphylococcal enterotoxin B, acute effect." Staphylococcal infections include folliculitis, furuncles (boils), impetigo, pneumonia, osteomyelitis, brain abscesses, spinal epidural abscesses, pericarditis, endocarditis, and septic arthritis. Spinal epidural abscess presents as radiating back pain and difficulty voiding or walking. [Harrison ID, p. 413t, 414] Findings of staphlococcal pneumonia are fever, cough, dyspnea, hemoptysis, leukopenia, and cavitating infiltrates. [PPID, p. 2427] Staphylococci are often the cause of breast abscesses or mastitis in nursing mothers. They are not a common cause of community pneumonia except in patients with influenza or immunosuppression. [Merck Manual, p. 1603] The USA300 strain causes most CA-MRSA (community-acquired, methicillin-resistant S. aureus) in the US. Patients with higher rates of colonization include insulin-dependent diabetics, HIV-infected, injection drug users, hemodialysis patients, and patients with skin damage. Prevention is through hand washing and appropriate isolation procedures. Mupirocin can be used to eliminate nasal carriage of S. aureus, resulting in reduced infections among intensive care patients. [Harrisons, p. 444, 448] S. aureus is the most common cause of endocarditis, osteomyelitis, septic arthritis, purulent pericarditis in children, and hospital-acquired pneumonia; it causes about 30% of surgical site infections in the US. The main sources of staphylococcal bacteremia are skin infections, central venous catheters, osteomyelitis, septic arthritis, pneumonia and endocarditis. Findings in endocarditis include Osler's nodes, petechiae, cough, hemoptysis, chest pain, pleural effusions, infiltrates, and cavitations. Cavitations also occur in staphylococcal pneumonia. Coagulase-negative staphylococci rarely cause infections in the absence of prosthetic devices and indwelling catheters. Positive blood cultures for these organisms represent contamination in about 75% of the cases. [Cecil, p. 1863-5, 1867] Pyomyositis (muscle pain and fever) is common in tropical countries. [Guerrant, p. 209] Staphylococci are uncommon causes of nodular lymphangitis; [Am Fam Physician 2001;63:326-32]
REFERENCES FOR CASES/YEAR
1. (US) Pathogenic species are ubiquitous--on the skin of 20% and in the anterior nares of about 30% of healthy adults; [Merck Manual, p. 1602] US incidence rates for S. aureus-invasive infections are 28.4 to 43.3 per 100,000; [PPID, 8th Ed, p. 2258] 35.9 X 3000 = 107,700;
2. (Global) About 10% of healthy people are "persistently colonized." [Harrison ID, p. 410] Estimate global cases/yr at 20 X US cases/yr;