Abstract & Commentary
Necrotizing Pneumococcal Pneumonia in Children due to Streptococcus pneumoniae
By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University School of Medicine, is Associate Editor for Infectious Disease Alert.
Dr. Winslow is a speaker for Cubist Pharmaceuticals and GSK, and is a consultant for Siemens Diagnostics.
Synopsis: One hundred twelve cases of pneumococcal pneumonia were seen between 2001 and 2010 at a children's hospital in Taiwan. Bronchopleural fistula (BPF) was encountered in 18 children. Lower WBC on admission, prolonged fever, acute respiratory failure, and infection with serotype 19A were associated with BPF.
Source: Hsieh YC, et al. Necrotizing pneumococcal pneumonia with bronchopleural fistula among children in Taiwan. Pediatr Infect Dis J 2011;30:740-744.
This study was conducted at the largest children's hospital in Taiwan. All pneumococcal isolates recovered from sterile sites from children hospitalized at this institution were maintained frozen at -20° C since 2000. Using the hospital database and medical records, all patients < 18 years of age who were hospitalized with culture-proven pneumococcal pneumonia between 2001 and 2010 were identified. Cases were divided into: 1) pneumonia without lung necrosis and 2) necrotizing pneumonia. The latter were subdivided further into pneumonia not complicated or pneumonia complicated by BPF. Standard antimicrobial susceptibility testing was performed on isolates. Serotype was determined by Quellung reaction using antisera obtained from the Statens Serum Institut (Denmark). A subset of isolates also was examined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence type using standard techniques.
During the period of study, 112 cases of culture-proven pneumococcal pneumonia were identified. Fifty-two percent of cases were complicated by empyema and 45% had necrotizing pneumonia, with 43% having both empyema and necrotizing pneumonia. Eighteen children developed BPF, all of whom had necrotizing pneumonia and empyema. Surgery was performed in 15 of 18 children with BPF and 12 children required lung resection.
The most common pneumococcal serotype seen in the 112 cases of pneumococcal pneumonia overall was type 14. From 2001 to 2010 the percentage of pneumococcal pneumonia caused by serotype 19A increased from 5% to 78%. Infection with serotype 19A was significantly associated with necrotizing pneumonia (P = 0.005) and with development of BPF (P = 0.02). All 12 isolates of type 19A pneumococcus belonged to multilocus sequence type clonal complex (CC) 320. Pathology data available for the 12 children who underwent surgical resection showed suppurative necrosis and abscess formation in 75% and coagulation necrosis was seen in 92% of cases.
This study showed that Streptococcus pneumoniae serotype 19A CC320 was strongly associated with necrotizing pneumococcal pneumonia and development of BPF. The increased frequency of isolation of this pathogen over the 10 years of the study is almost certainly related to two factors: the replacement of serotypes, including in the PCV7 vaccine, by non-vaccine serotypes and possibly antibiotic selection since an increased frequency of isolation of serotype 19A also has been seen in countries where use of PCV7 has been low.
In addition to causing necrotizing pneumonia, type 19A has become a predominant cause of other invasive pneumococcal disease syndromes, including empyema, mastoiditis, and hemolytic uremic syndrome. This study is interesting since it reported a comprehensive experience with invasive pneumococcal disease in children over a 10-year period and included pathology data. The common finding of pulmonary infarction in resected lung tissue in addition to abscess formation is striking and suggests that this pathogen contributed to arteritis and vascular thrombosis. Clearly, serotype 19A pneumococcus is a formidable pathogen (and seems to me to have some parallels to S. millerigroup organisms). Further research to understand the pathogenicity of this organism, as well as host-pathogen relationships, would seem to be a fruitful area of study.