Comparison of four methods for rapid identification of Staphylococcus aureus directly from BACTEC 9240 blood culture system

PURPOSE

Differentiation of Staphylococcus aureus (S. aureus) from coagulase-negative staphylococci is very important in blood stream infections. Identification of S. aureus and coagulase-negative staphylococci (CoNS) from blood cultures takes generally 18-24 h after positive signaling on continuously monitored automated blood culture system. In this study, we evaluated the performance of tube coagulase test (TCT), slide agglutination test (Dry Spot Staphytect Plus), conventional polymerase chain reaction (PCR) and LightCycler Staphylococcus MGrade kit directly from blood culture bottles to achieve rapid identification of S. aureus by using the BACTEC 9240 blood culture system.

MATERIALS AND METHODS

A total of 129 BACTEC 9240 bottles growing gram-positive cocci suggesting Staphylococci were tested directly from blood culture broths (BCBs) with TCT, Dry Spot Staphytect Plus, conventional PCR and LightCycler Staphylococcus MGrade kit for rapid identification of S. aureus.

RESULTS

The sensitivities of the tests were 99, 68, 99 and 100%, respectively.

CONCLUSION

Our results suggested that 2 h TCT was found to be simple and inexpensive method for the rapid identification of S. aureus directly from positive blood cultures.

Bone marrow infection caused by Mycobacterium avium complex in a patient with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a disease with wide range of signs and symptoms. SLE patients have increased infective diathesis, and infections are a very important cause of death in these patients. Infections can sometimes mimic the signs and symptoms of SLE. Thus, it is important to recognize that infection can induce a lupus flare-up or can be difficult to distinguish from a lupus flare-up. We describe a 36-year-old female patient with SLE, who presented with skin lesions and pancytopenia, and clinical manifestations similar to a flare-up of SLE. Bone marrow examination revealed infection with Mycobacterium avium complex (MAC). The patient had no history or clinical evidence of pulmonary involvement. This patient is the first case of invasive bone marrow MAC infection in SLE. With this unique case, we would like to emphasize that SLE patients can also be infected by non-tuberculous mycobacteria, and that bone marrow examination for tuberculosis as well as for non-tuberculosis mycobacteria should be considered in SLE patients with refractory pancytopenia.

Seroprevalence of antibodies to legionella pneumophila in hemodialysis patients

Patients with chronic renal failure are at increased risk for infections because of impaired cellular immunity. This study was designed to determine the prevalence of antibodies to Legionella pneumophila serogroups 1 to 6 and to evaluate the possible risk factors for Legionnaires' disease in hemodialysis patients. Serum samples to be screened for antibodies against L pneumophila and risk factor data were collected from 252 hemodialysis patients. The overall prevalence of L pneumophila antibodies in hemodialysis patients was found to be 5.16% There was no statistically significant difference between L pneumophila seropositivity and potential risk factors. Further studies are needed to determine possible risk factors for Legionnaires' disease in hemodialysis patients.