Antimicrobial resistance of community-acquired bloodstream isolates of viridans group streptococci.

Infections due to antimicrobial-resistant viridans group streptococci are increasing. The present study was done to determine the frequency of antibiotic resistance among community-acquired viridans group streptococci isolated from blood cultures and to identify the risk factors associated with acquiring antibiotic-resistant viridans group streptococci. Twenty-eight community-acquired viridans group streptococcal isolates were recovered from 27 patients, of which 89%, 86%, 79%, 61%, and 39% were susceptible to ceftriaxone, clindamycin, tetracycline, penicillin, and erythromycin, respectively; 100% were susceptible to levofloxacin and vancomycin. Among the patients with previous antibiotic use, 73% had penicillin non-susceptible viridans group streptococci, compared with 18% who did not receive prior antibiotics (p = 0.006). Patients with and without prior antibiotic use, 27% and 0%, respectively, had ceftriaxone non-susceptible viridans group streptococci isolates, respectively (p = 0.05). Patients with and without prior antibiotic use, 45% and 6%, respectively, had tetracycline non-susceptible viridans group streptococci isolates, respectively (p = 0.02). No other risk factors for isolation of non-susceptible viridans group streptococci were identified.