Staphylococcus aureus bacteremic syndromes: diagnostic and therapeutic update

Serum antibody to staphylococcal teichoic acid and alpha-haemolysin in dermatological patients

Teichoic acid antibody (TAA) titres and antibody to alpha-haemolysin of Staphylococcus aureus (ASta) were measured in 274 dermatological patients and 200 normal controls. Positive ASta values (greater than or equal to 2.0 iu/ml) were common in patients with chronic pruritic dermatoses such as atopic dermatitis (44% ASta positive) and infective eczema (28% ASta positive), but patients with primary pyoderma were all ASTa negative. Positive TAA titres (greater than or equal to 1:4) were seen less frequently than positive ASta values, but still significantly more often in atopic dermatitis patients than in controls. Routine skin swabs were taken from all patients, but positive TAA or ASta tests correlated neither with growth of Staphylococcus aureus from skin lesions nor with signs of clinical infection. This study shows that the TAA test cannot be used as an indicator of septic staphylococcal infection in patients with atopic dermatitis.

Assay of teichoic acid antibodies and antistaphylolysin in the diagnosis of Staphylococcal osteomyelitis

Teichoic acid antibodies (TAA), measured by gel diffusion, and antistaphylolysin (ASa) values were determined in 46 osteomyelitis patients and 200 healthy controls. A positive TAA titer (greater than or equal to 4) was seen in 4/16 patients with acute hematogenous osteomyelitis caused by Staphylococcus aureus and in 7/22 patients with chronic staphylococcal osteomyelitis, while ASta was positive (greater than or equal to 2.0 IU/ml) in 9 patients in both groups all except 2 exceeding 4.0 IU/ml. No positive TAA titres or ASta values were seen in 8 patients with chronic nonstaphylococcal osteomyelitis. The rate of positive test results in 200 controls was 7% for TAA and 4% for ASta. Basing diagnosis on a positive value in either of the tests gave 21 positive results in 38 patients with staphylococcal osteomyelitis; 18 by ASta alone and 11 by TAA alone. Both tests were positive at the same time in 3 patients with acute and in 5 patients with chronic staphylococcal osteomyelitis but never in controls.

Methicillin-resistant Staphylococcus aureus bacteraemia

Twenty-eight (53%) of 53 hospital-acquired staphylococcal bacteraemias which occurred at The Royal Melbourne Hospital over a two-year period were due to methicillin-resistant Staphylococcus aureus (MRSA). Every patient with MRSA bacteraemia had a significant underlying condition predisposing to nosocomial sepsis, and each had an intravascular foreign body in situ at the time. Most were being nursed in special care areas of the hospital and had been exposed to multiple or broad-spectrum antibiotics during the month before development of bacteraemia. Patients acquiring MRSA infection should be isolated and, when the diagnosis of bacteraemia is considered, any potential primary focus should be removed. Vancomycin is the drug of choice in life-threatening MRSA infections.