A comparison of clinical characteristics between nutritionally variant streptococci (NVS) and viridans streptococci

Abstract

Background NVS is a fastidious group of streptococci that can give rise to serious invasive infections in humans. Apart from endocarditis, clinical features of this group of pathogens have not been compared with other more commonly encountered streptococci Purpose of study The demographics, clinical features and outcome of patients with nutritionally variant streptococci infection were compared with a concurrent cohort of patients with viridans streptococci infection Study design. The clinical and microbiological data of hospitalized adult patients from year 2002 to 2011 infected with nutritionally variant streptococci or viridans streptococci were analysed. Results A total of 241 patients including 21 NVS and 220 viridans streptococci were analysed. The mean age of NVS patients was lower than viridans streptococci (54.7 vs 63.9, p = 0.042). When compared with 63 age and sex matched viridans streptococci controls, significantly more NVS patients have hematological malignancy (p=0.007) and had fever at the time of presentation (p=0.012). They are more common to have bone and joint infection (p=0.032), line sepsis (p=0.013) and primary bacteremia (p=0.039). Most isolates of NVS were from blood culture specimens (p=0.002). There were no statistical significance in terms of 30-day mortality and length of hospital stay between the two groups. Conclusion NVS tends to infect slightly younger patients, patients with hematological malignancy and cause more bacteremia than viridans streptococci. It is important not to discard positive blood culture isolate with NVS as contaminant.