Penicillin Resistance in Viridans Streptococcal Bacteremia is Related with High Mortality

Sir, Viridans streptococci (VS) are a significant cause of bacteremia in neutropenic patients with cancer, in those with endocarditis or in patients after dental surgery or endoscopy. These infections have traditionally been associated with limited morbidity, but serious complications such as septicaemic shock and adult respiratory distress syndrome (ARDS) have been described sporadically in recent years (1, 2). Clinical significance has been demonstrated in penicillin resistant (PEN-R) S. pneumoniae in several studies (3, 4); however, in viridans streptococci only one study in cancer patients (5) revealed in a multivariate fashion that those infected with PEN-R strains had higher mortality in comparison to individuals infected with PEN / susceptible VS. This was not demonstrated with erythromycin resistance (ERY-R) (6). The aim of this short letter is to assess the clinical significance and outcome of PEN and ERY resistance of VSB within a national bacteremia survey in Slovakia. Within 2 y, 127 cases of viridans streptococcal bacteremia (VSB) were observed in national surveillance of streptococcal bacteremia in Slovakia: assessing risk factors and impact of PEN-R on mortality, we compared PEN-R VSB to PEN-S VSB. 111 cases were due to penicillin susceptible (PEN-S) and 16 due to penicillin resistant (PEN-R) VSB (Table I). 13% of VSB cases were caused by PEN-R strains. Risk factors for penicillin resistance (MIC /2 mg/ml) were ventilatory support (p B/0.01), intubation (p B/0.001) and resistance to other antibiotics; 44% of PEN-R VSB were resistant also to erythromycin or cotrimoxazol or tetracycline in comparison to 7% of PEN-R VSB (p B/0.005). Endoscopic procedures in the upper respiratory system were at risk for development of PEN-R VSB. Also, there was difference in outcome, 69% vs 21% (p B/0.0002) of cases infected with PEN-RVSB dying in comparison to PEN-S VSB. Penicillin resistance is therefore clinically significant in viridans streptococcal bacteremia.