Beta-Hemolytic Streptococcal Infection

Breese, Burtis B.; Disney, Frank A.; Talpey, William B.; Green, John L.

doi:10.1001/archpedi.1970.02100050020006

Cited by 55 publications

(19 citation statements)

References 7 publications

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“…Relatively little is known about the molecular factors that contribute to development of an asymptomatic carrier state in microbial pathogens. This is important because, for GAS, evidence indicates that asymptomatic carriers are less likely than individuals with clinically significant infections to disseminate organisms and develop postinfection sequelae (19)(20)(21). In principle, asymptomatic carriage could occur because genetic changes in the pathogen mitigate virulence.…”

Section: Resultsmentioning

confidence: 99%

Molecular genetic anatomy of inter- and intraserotype variation in the human bacterial pathogen group A Streptococcus

Beres

Richter

Nagiec

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

202

177

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In recent years we have studied the relationship between strain genotypes and patient phenotypes in group A Streptococcus (GAS), a model human bacterial pathogen that causes extensive morbidity and mortality worldwide. We have concentrated our efforts on serotype M3 organisms because these strains are common causes of pharyngeal and invasive infections, produce unusually severe invasive infections, and can exhibit epidemic behavior. Our studies have been hindered by the lack of genome-scale phylogenies of multiple GAS strains and whole-genome sequences of multiple serotype M3 strains recovered from individuals with defined clinical phenotypes. To remove some of these impediments, we sequenced to closure the genome of four additional GAS strains and conducted comparative genomic resequencing of 12 contemporary serotype M3 strains representing distinct genotypes and phenotypes. Serotype M3 strains are a single phylogenetic lineage. Strains from asymptomatic throat carriers were significantly less virulent for mice than sterile-site isolates and evolved to a less virulent phenotype by multiple genetic pathways. Strain persistence or extinction between epidemics was strongly associated with presence or absence, respectively, of the prophage encoding streptococcal pyrogenic exotoxin A. A serotype M3 clone significantly underrepresented among necrotizing fasciitis cases has a unique frameshift mutation that truncates MtsR, a transcriptional regulator controlling expression of genes encoding ironacquisition proteins. Expression microarray analysis of this clone confirmed significant alteration in expression of genes encoding iron metabolism proteins. Our analysis provided unprecedented detail about the molecular anatomy of bacterial strain genotypepatient phenotype relationships.carrier ͉ epidemic ͉ genomic resequencing ͉ SNP ͉ phylogeny M icrobial epidemics have repeatedly altered the course of history by decimating human populations, killing domesticated animals, and blighting crops. Despite the impact of these destructive events, we know relatively little about the evolutionary genetic events contributing to bacterial strain emergence and diversification within and between epidemic waves. Also poorly understood is the molecular basis of intraspecies variation in disease phenotype. The recent confluence of genome sequencing and development of high-throughput techniques to interrogate genetic polymorphisms in large samples of strains now permits these topics to be studied at the individual nucleotide level.Group A Streptococcus (GAS) infects humans worldwide and causes an array of diseases ranging from superficial infections such as pharyngitis to fulminant invasive infections characterized by high morbidity and mortality (1, 2). In recent years, we have used serotype M3 GAS strains as model pathogens for studying the molecular processes contributing to clone emergence, epidemic waves, and genotype-phenotype relationships (M protein is a highly polymorphic cell-surface molecule that is antiphagocytic and forms the bas...

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Section: Resultsmentioning

confidence: 99%

Molecular genetic anatomy of inter- and intraserotype variation in the human bacterial pathogen group A Streptococcus

Beres

Richter

Nagiec

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

202

177

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“…Even a relatively insensitive RADT may be superior to clinical judgment alone. Studies indicate that even experienced clinicians diagnose GABHS pharyngitis correctly only 75 to 80% of the time when the diagnosis is based on clinical assessment alone (6,7).…”

Section: Medical Decision Makingmentioning

confidence: 99%

Rapid Diagnosis of Pharyngitis Caused by Group A Streptococci

2004

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Although commercial rapid antigen detection tests (RADTs) are more expensive than blood agar plate (BAP) cultures, the advantage they offer is the speed with which they provide results. Rapid identification and consequent prompt treatment of patients with pharyngitis due to group A beta-hemolytic streptococci (GABHS) can reduce the risk of spread of GABHS, can allow patients to return to school or work sooner, and may reduce the acute morbidity of this illness. In most studies, RADTs have been compared with BAP cultures as the criterion standard. However, these comparisons are complicated by the fact that there is no universally accepted procedure for performing a BAP culture. The great majority of the RADTs that are currently available have a high specificity (i.e., 95% or greater) and a sensitivity of between 70 and 90% compared with BAP cultures. Few published studies have compared the performance of various RADTs to each other or examined the performance of various RADTs in the office setting. There is also relatively little published information about how physicians in practice actually use RADTs, but the available information suggests that many physicians do not follow recommended guidelines. While the development of easy-to-perform RADTs for the diagnosis of GABHS pharyngitis has altered clinical practice substantially, only limited data about cost-effectiveness are currently available

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“…It is well known that streptococcal throat infection, in a temperate climate, is a disease of the winter and early spring (1,7,8). Our intention was to compare patients with a sore throat and healthy individuals during periods when we could expect maximal and minimal prevalence of BHS among patients.…”

Section: Seasonal Variationmentioning

confidence: 99%

“…Some of these patients may have a virus infection and are only carriers of GABHS (1,(3)(4)(5). and may not benefit from treatment with antibiotics at that time (4,6). It would be of interest to identify the characteristics of those patients.…”

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confidence: 99%