Objectives.We report three very unusual cases of fulminant necrotizing pneumonia caused by S.pyogenes, emm1 type, which occurred in Italy in 2010-2012. All patients showed a very similar clinical syndrome: high fever, respiratory failure, hemoconcentration, neutropenia and severe sepsis-septic shock and died within 24 h after admission. The main objectives are the molecular characterization of S.pyogenes strains by: i) detection of M-type, ii) identification of Sequence typing (ST) and Clonal complex (CC), iii) antibiotic susceptibility and iv) virulence profile. Methods. Three cases of S.pyogenes pneumonia are: RM1 admitted to the University Hospital Umberto I, Rome; RMG1 admitted to the University Hospital Agostino Gemelli, Rome; CT1 admitted to the Vittorio Emanuele Hospital of Catania. Antibiotic susceptibilities were tested by EUCAST guidelines. The emm-typing and ST were performed by CDC emm database and following MLST guidelines. The virulence profile (SLO, sagA/BC, smeZ-2, speB/A/C, speG/I/J, prtF, PAM, sof, ssa, sda1) was performed by PCR. Results. All S.pyogenes were susceptible to erythromycin, amoxicillin, penicillin, clindamycin and clarithromycin. The emm-typing demonstrated that all strains belonged to emm-type 1.0 and ST analysis demonstrated that RMG1 and CT1 belonged to ST28 (CC28), while for RM1, we found a new single locus variant of ST28 designated ST648. For the virulence profile, M-type1/ST28 S.pyogenes SF370 was included as control. We found a homogeneous content of virulence genes and if compared with SF370, only few exceptions were found: speC (only in SF370), speA and sda1 (absent in SF370). Conclusion.This study highlights the increase of invasive GAS in Italy: 3 cases of pneumonia in 1 year. Our studies show that virulence profiles and belonging to specific M-type/ST are not responsible for fulminant necrotizing pneumonia and that many other factors in the interaction between host and GAS could be involved ie CovRS genes. Further studies are ongoing in our laboratory in order to possibly correlate CovRS genes and their role in expression of virulence genes in these S.pyogenes strains.
Three cases of fulminant hemorrhagic pneumoniae in healthy immunocompetent individuals, due to invasive Streptococcus pyogenes M1-Type
SANTAGATI, Maria Carmela;Stefania Stefani
2013-01-01
Abstract
Objectives.We report three very unusual cases of fulminant necrotizing pneumonia caused by S.pyogenes, emm1 type, which occurred in Italy in 2010-2012. All patients showed a very similar clinical syndrome: high fever, respiratory failure, hemoconcentration, neutropenia and severe sepsis-septic shock and died within 24 h after admission. The main objectives are the molecular characterization of S.pyogenes strains by: i) detection of M-type, ii) identification of Sequence typing (ST) and Clonal complex (CC), iii) antibiotic susceptibility and iv) virulence profile. Methods. Three cases of S.pyogenes pneumonia are: RM1 admitted to the University Hospital Umberto I, Rome; RMG1 admitted to the University Hospital Agostino Gemelli, Rome; CT1 admitted to the Vittorio Emanuele Hospital of Catania. Antibiotic susceptibilities were tested by EUCAST guidelines. The emm-typing and ST were performed by CDC emm database and following MLST guidelines. The virulence profile (SLO, sagA/BC, smeZ-2, speB/A/C, speG/I/J, prtF, PAM, sof, ssa, sda1) was performed by PCR. Results. All S.pyogenes were susceptible to erythromycin, amoxicillin, penicillin, clindamycin and clarithromycin. The emm-typing demonstrated that all strains belonged to emm-type 1.0 and ST analysis demonstrated that RMG1 and CT1 belonged to ST28 (CC28), while for RM1, we found a new single locus variant of ST28 designated ST648. For the virulence profile, M-type1/ST28 S.pyogenes SF370 was included as control. We found a homogeneous content of virulence genes and if compared with SF370, only few exceptions were found: speC (only in SF370), speA and sda1 (absent in SF370). Conclusion.This study highlights the increase of invasive GAS in Italy: 3 cases of pneumonia in 1 year. Our studies show that virulence profiles and belonging to specific M-type/ST are not responsible for fulminant necrotizing pneumonia and that many other factors in the interaction between host and GAS could be involved ie CovRS genes. Further studies are ongoing in our laboratory in order to possibly correlate CovRS genes and their role in expression of virulence genes in these S.pyogenes strains.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.