β-Haemolytic group A streptococci emm75 carrying altered pyrogenic exotoxin A linked to scarlet fever in adults

• Published in: The Journal of infection Vol. 56; no. 4; pp. 261 - 267
• Main Authors: Dong, Hongjun, Xu, Guozhang, Li, Shuhua, Song, Qifa, Liu, Shijian, Lin, Hui, Chai, Yibiao, Zhou, Aimin, Fang, Ting, Zhang, Hongwei, Jin, Chunguang, Lu, Wei, Cao, Guangwen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2008; Elsevier
• Subjects: Adolescent; Adult; Ampicillin - pharmacology; Animals; Anti-Bacterial Agents - pharmacology; Bacterial Toxins - genetics; Biological and medical sciences; Cephalexin - pharmacology; Chickens - microbiology; Child; China - epidemiology; Databases, Nucleic Acid; Disease Outbreaks; Exotoxin; Exotoxins - genetics; Food Contamination; Food-borne; General aspects; Genotype; Humans; Medical sciences; Microbial Sensitivity Tests; Middle Aged; Phylogenesis; Polymerase Chain Reaction; Scarlet fever; Scarlet Fever - drug therapy; Scarlet Fever - epidemiology; Scarlet Fever - microbiology; Streptococcal Infections - drug therapy; Streptococcal Infections - microbiology; Streptococcus pyogenes - genetics; Streptococcus pyogenes - isolation & purification; Wounds and Injuries - complications; Wounds and Injuries - microbiology; β-Haemolytic group A streptococci; China; β-Haemolytic group A streptococci; Food-borne; Genotype; Phylogenesis; Exotoxin; Scarlet fever; Human; Infection; Streptococcaceae; Toxin; Streptococcal infection; Streptococcus A; Bacteriosis; Bacteria; Micrococcales; Adult
• ISSN: 0163-4453; 1532-2742
• DOI: 10.1016/j.jinf.2008.01.047

To determine the etiological cause of a food-borne outbreak of scarlet fever in adults. Swabs from the throats of the patients and asymptomatic control were cultured on blood agar plates individually. Biochemical identification of all isolates was performed with a VITEX automated system. Antibiotic susceptibility was examined by using the Kirby–Bauer disc diffusion method. emm gene and extracellular pyrogenic exotoxins of each isolate were amplified by using polymerase chain reaction and subjected to DNA sequencing. Sequence differences between the isolated and the highly similar reference sequences were compared on BLAST. Bioinformatics was used to predict protein structures. β-Haemolytic group A streptococci (GAS) emm75 were identified from 10 of 13 available patients. The isolates were susceptible to penicillin, ampicillin, vancomycin, cefatriaxone, ofloxacin, linezolid and quinupristin. All of the isolates carried pyrogenic exotoxin A ( speA) and cysteine protease ( speB). Isolated speA was phylogenetically different from 30 highly similar references on BLAST. Differences in the primary sequence of the deduced protein were 14.37–20.12% between the speA and each of 11 references. Secondary protein structure of the speA was different from the references at the N-terminal. GAS emm75 encoding altered speA was responsible for the food-borne outbreak of scarlet fever in adults.