Nosocomial bloodstream infections due to viridans streptococci in haematological and non-haematological patients: species distribution and antimicrobial resistance.

Objectives: We studied the species distribution and antimicrobial susceptibility of viridans streptococci (VS) isolates causing nosocomial bloodstream infections (BSIs) in Finnish hospitals.

Patients And Methods: Patients with nosocomial BSIs due to VS were identified through a hospital-wide prospective laboratory-based surveillance in two university and two regional hospitals during September 1998-August 2001. Isolates of VS were sent to the reference laboratory for species confirmation and antimicrobial susceptibility testing.

Results: A total of 2038 nosocomial BSIs were identified; 108 (5%) of the BSIs were caused by VS. Of the VS BSIs, 66% were in patients with a haematological malignancy, 14% in patients with a solid tumour and 18% in patients who had undergone surgery preceding the infection. The most common species group identified was Streptococcus mitis (82%). High-level penicillin resistance (> or = 4 mg/L) and cefotaxime resistance (> or = 4mg/L) were present in 5% and 4% of isolates, respectively; both were detected only in haematological patients. However, in non-haematological patients, resistance to erythromycin (17%), and reduced susceptibility to levofloxacin (14%) and penicillin (19%) were common.

Conclusions: The resistance problems in VS are not limited to haematological patients. These findings may have significant clinical implications in the choice of both empirical antibiotic and antimicrobial prophylaxis regimens.