High yield of blood cultures in the etiologic diagnosis of cellulitis, erysipelas, and cutaneous abscess in elderly patients

Background

Cellulitis is a common disease in the elderly, and detecting etiologic organisms with blood cultures is difficult because of the low positive rate and occasional skin contamination. Therefore, routine blood cultures are not recommended for uncomplicated cellulitis. However, it is unclear whether blood culture collection for the diagnosis of cellulitis in elderly patients is useful.

Methods

This single hospital–based observational study was performed between April 2012 and March 2015 in Okinawa, Japan. All enrolled patients were aged 15 years or older and admitted to the Division of Infectious Diseases with suspected cellulitis, erysipelas, and cutaneous abscess. Two routine sets of blood cultures were obtained.

Results

Two hundred and twenty-one patients were enrolled. The median age was 77 years. The proportion of bacteremia was 21.7% for all patients (48/221), 8.5% (4/47) for those <65 years, and 25.3% (44/174) for those ≥65 years old (P = .013). The skin contamination rate was 0.9% (2/221). The most common pathogen was Streptococcus dysgalactiae (62.5%). Gram-negative bacteremia not susceptible to cefazolin was detected in 8.3%. Cefazolin and ampicillin were the first- and second-most commonly used therapies. Anti–methicillin-resistant Staphylococcus aureus therapy was required in 3.6% of patients. In addition to age and severe infection, shaking chills and white blood count ≥13 000 cells/µL were independent risk factors of bacteremia.

Conclusions

Two routine sets of blood cultures are recommended for the precise diagnosis and appropriate treatment of cellulitis in elderly patients, especially in patients with shaking chills or leukocytosis.

Purification of liver serine protease which activates microsomal glutathione S-transferase: possible involvement of hepsin

Rat liver microsomal glutathione S-transferase (MGST1) is known to be activated by trypsin, however, it has not been clarified whether MGST1 is activated by a protease present in liver. In the present study we purified the MGST1 activating protease from liver microsomes and finally identified that the protease is hepsin, a type II transmembrane serine protease. When the protease was incubated with the purified MGST1 or liposomal MGST1 at 4 degrees C, MGST1 activity was increased 3-4.5 fold after 3-6 d. In electrophoretic and immunoblot analyses after the incubation of MGST1 with the protease MGST1 dimer and its degraded fragment were detected. These results suggest that the rat liver microsomal hepsin functions as MGST1 activating/degrading enzyme.