Matrix-assisted laser desorption ionization-time of flight and comparative genomic analysis of M-18 group a Streptococcus strains associated with an acute rheumatic fever outbreak in northeast Italy in 2012 and 2013.
Acute rheumatic fever (ARF) is a postsuppurative sequela caused by Streptococcus pyogenes infections affecting school-age children. We describe here the occurrence of an ARF outbreak that occurred in Bologna province, northeastern Italy, between November 2012 and May 2013. Molecular analysis revealed that ARF-related group A Streptococcus (GAS) strains belonged to the M-18 serotype, including subtypes emm18.29 and emm18.32. All M-18 GAS strains shared the same antigenic profile, including SpeA, SpeB, SpeC, SpeL, SpeM, and SmeZ. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis revealed that M-18 GAS strains grouped separately from other serotypes, suggesting a different S. pyogenes lineage. Single nucleotide polymorphisms and phylogenetic analysis based on whole-genome sequencing showed that emm18.29 and emm18.32 GAS strains clustered in two distinct groups, highlighting genetic variations between these subtypes. Comparative analysis revealed a similar genome architecture between emm18.29 and emm18.32 strains that differed from noninvasive emm18.0 strains. The major sources of differences between M-18 genomes were attributable to the prophage elements. Prophage regions contained several virulence factors that could have contributed to the pathogenic potential of emm18.29 and emm18.32 strains. Notably, phage ΦSPBO.1 carried erythrogenic toxin A gene (speA1) in six ARF-related M-18 GAS strains but not in emm18.0 strains. In addition, a phage-encoded hyaluronidase gene (hylP.2) presented different variants among M-18 GAS strains by showing internal deletions located in the α-helical and TSβH regions. In conclusion, our study yielded insights into the genome structure of M-18 GAS strains responsible for the ARF outbreak in Italy, thus expanding our knowledge of this serotype.
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy paolo.gaibani@unibo.it.
Paolo
P
Gaibani
Sezione Diagnostica di Parma, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Parma, Italy.
Erika
E
Scaltriti
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy.
Claudio
C
Foschi
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy.
Enrico
E
Baggio
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy.
Maria Vittoria
MV
Tamburini
Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Rome, Italy.
Roberta
R
Creti
Public Health Authority Emilia Romagna, Rome, Italy.
Maria Grazia
MG
Pascucci
Bruker Daltonics s.r.l., Macerata, Italy.
Marco
M
Fagioni
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy.
Simone
S
Ambretti
Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milan, Italy.
Francesco
F
Comandatore
Sezione Diagnostica di Parma, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Parma, Italy.
Stefano
http://orcid.org/0000-0002-4823-3562
S
Pongolini
Operative Unit of Clinical Microbiology, St. Orsola-Malpighi University Hospital, Bologna, Italy.
Maria Paola
MP
Landini
D000818:Animals; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D005260:Female; D016680:Genome, Bacterial; D023281:Genomics; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008828:Microbiological Techniques; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D039002:Prophages / Q000235:genetics; D012213:Rheumatic Fever / Q000175:diagnosis* / Q000453:epidemiology*; D012703:Serotyping; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013297:Streptococcus pyogenes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D037521:Virulence Factors / Q000235:genetics
D004269:DNA, Bacterial; D037521:Virulence Factors