Isolation of beta-hemolytic streptococci from the respiratory tract: distribution and clinical significance

Group-C beta-hemolytic streptococcal bacteremia

Group-C beta-hemolytic streptococci (GCBHS) is an uncommon cause of bacteremia. In a 5-year period, GCBHS accounted for 0.28% of positive blood cultures and 0.35% of bacteremias documented at our hospital. The incidence of GCBHS bacteremia was 0.05 episodes per 1000 admissions. We were able to analyze clinical data of 10 of the 13 patients with GCBHS bacteremias. All but one were adults with significant underlying diseases, and seven episodes were community acquired. The skin was the portal of entry in only one case. Clinical syndromes included primary bacteremia (four cases), pneumonia (two cases), endocarditis (two cases), and meningitis, intraabdominal infection, and metastatic suppurative pericarditis (one episode each). Of 13 isolates, 12 were identified to species level: six, Streptococcus equisimilis; three S. equi; two S. dysgalactiae; and one S. zooepidemicus. Resistance to penicillin was detected in one isolate and none of our isolates displayed penicillin tolerance, Four patients died (40%) despite appropriate antimicrobial therapy.

Group F streptococcal empyema from aspiration of a grass inflorescence

A previously healthy 15-year-old boy was seen with a loculated right lower lobe empyema. Group F beta-hemolytic streptococci were cultured from the pleural fluid. Surgical intervention was required. An unsuspected aspirated grass inflorescence and a bronchopleural fistula were discovered during a decortication procedure.

Emerging pathogens in nosocomial pneumonia

The organisms responsible for nosocomial pneumonia are continuously evolving. Gram-negative bacilli have become the most common etiologic agents over the past 20 years, and with this evolution has come a better understanding of the pathogenesis of gram-negative bacillary pneumonia. Some gram-positive cocci, such as enterococci, group B beta hemolytic streptococci and methicillin-resistant Staphylococcus aureus, haven taken on new significance in nosocomial respiratory infections. Streptococcus pneumoniae, nontypeable Haemophilus influenzae and Branhamella catarrhalis are increasingly reported in hospitalized patients with chronic lung disease. Etiologic agents will change as new antibiotics are introduced. A better understanding of etiologic agents and their pathogens may be the best tool toward preventing hospital-acquired pneumonia.