Abstract :Purpose: To review the current epidemiology and incidence of Group a streptococcal (GAS) pneumonia in our community teaching hospital as part of our quality improvement project for care of patients with GAS bacteremia.
Methods: We reviewed the blood culture logs for all patients for the twelve-year period from January 1, 2006 to December 31, 2017. All patients with positive blood cultures for Streptococcus pyogenes were recorded and all charts were reviewed to determine age, sex, date, comorbid conditions, radiographic findings, complications, treatment and outcome.
Results: We identified 68 patients with GAS bacteremia, nine of whom were diagnosed with pneumonia. Pneumonia was the second most common identifiable cause of GAS bacteremia behind only skin and soft tissue infections identified in 29 patients. Patients with GAS pneumonia ranged in age from 31 to 86 years with a mean of 64.9 years and a median of 68 years. There were 5 men (56%) and 4 women (44%). Cases occurred in January (1 case), March (1 case), April (3 cases), May (1 case), June (1 case), November (1 case), and December (1 case). GAS was isolated from the blood only in 7 patients and from both blood and sputum in 2 patients. The most commonly observed comorbidities were: hypertension (4 cases), chronic obstructive pulmonary disease (3 cases), coronary artery disease (3 cases), diabetes mellitus (2 cases) and intravenous drug use (2 cases). One patient had influenza just preceding the episode of GAS pneumonia. One patient had influenza just preceding the episode of GAS pneumonia. Radiographic findings included lower lobe infiltrates in 7 patients: 3 bilateral, 3 right- sided, and 1 left-side.
One patient had right upper lobe infiltrates and one patient had bilateral interstitial infiltrates. Two patients developed empyema requiring tube thoracostomy and one of these two required lobectomy and pleural peel procedure. Because of severity of illness at time of presentation, all 9 patients received almost immediate appropriate parenteral antimicrobial therapy before definitive diagnosis was made. 7 patients received piperacillin/tazobactam, 1 patient received ceftriaxone, and 1 patient received moxifloxacin. 7 patients survived and 2 died (72 years and 82 years old) for a mortality rate of 22.2%.
Conclusions: Bacteremic GAS pneumonia was observed throughout the study period, presented with clinical illness indistinguishable from other acute bacterial pneumonias, and had a significant complication rate: empyema in 2 patients who survived and death in 2 other patients (overall severe complication rate = 44.4%). We review the literature and compare our patients with those reported in isolated intermittent GAS pneumonia case reports, to those reported in longitudinal studies similar to ours, to those reported in post-influenza pneumonia outbreaks, and to those in closed-population outbreaks such as in military bases and special residential homes. Streptococcus pyogenes (GAS) remains a significant pathogen in patients with bacteremic, primarily lobar pneumonia and causes significant morbidity and mortality despite early and appropriate antimicrobial therapy. It also is an organism without a vaccine thereby making it a potential pathogen for influenza-related or closed- population-related -pneumonia far into the future.