Epidemiología de la faringitis estreptocócica. Período enero de 2018 - diciembre de 2021 / Epidemiology of streptococcal pharyngitis. January 2018 - December 21

La faringoamigdalitis es uno de los motivos más frecuentes de consulta en pediatría. Aproximadamente un 70-80% de las faringoamigdalitis son de etiología viral. El 20-30% restante son de origen bacteriano. El agente causal más frecuente es Streptococcus pyogenes (estreptococo ß-hemolítico del grupo A). El rol de Streptococcus dysgalactiae subsp. equisimilis, (estreptococos ß-hemolíticos grupos C y G) fue claramente establecido como agente etiológico en la faringitis bacteriana, tanto en niños como en adultos. Se realizó un análisis descriptivo y retrospectivo entre enero 2018 y diciembre de 2021. Se evaluó la prevalencia de faringitis estreptocócica, la edad, el período estacional, los agentes etiológicos y la resistencia a macrólidos durante los períodos pre-COVID-19 (2018-2019) y COVID-19 (2020-2021). Se analizaron 11 396 muestras de exudados de fauces de pacientes con sospecha de faringitis bacteriana; las mismas se procesaron mediante el uso de técnicas microbiológicas convencionales. En el período estudiado el porcentaje de positividad de los cultivos de exudados de fauces se mantuvo constante. Al comparar los períodos pre-COVID-19 (2018-2019) y COVID-19 (2020-2021) se observó una disminución en el número de aislados de S. pyogenes con un aumento de S. dysgalactiae subsp. equisimilis, mientras que la resistencia a macrólidos encontrada fue superior en S. pyogenes y para S. dysgalactiae subsp. equisimilis se mantuvo constante. Es importante realizar el cultivo para la identificación del agente etiológico y determinar la sensibilidad antibióticapara continuar con la vigilancia epidemiológica de la resistencia a los macrólidos, porque representan una opción en pacientes alérgicos a ß-lactámicos (AU)

Pharyngotonsillitis is one of the most frequent reasons for consultation in children. Approximately 70-80% of pharyngotonsillitis are of viral etiology. The remaining 20-30% are bacterial in origin. The most frequent causative agent is Streptococcus pyogenes (group A ß-hemolytic streptococcus). Streptococcus dysgalactiae subsp. equisimilis (ß-hemolytic streptococcus groups C and G) was clearly established as an etiologic agent in bacterial pharyngitis in both children and adults. A descriptive and retrospective analysis was conducted between January 2018 and December 2021. The prevalence of streptococcal pharyngitis, age, seasonal period, etiologic agents, and macrolide resistance during the pre-COVID-19 (2018-2019) and COVID-19 (2020-2021) periods were evaluated. We analyzed 11 396 specimens of swabs from patients with suspected bacterial pharyngitis. Conventional microbiological techniques were used. In the study period, the percentage of positivity of swab cultures remained constant. When comparing the preCOVID-19 (2018-2019) and COVID-19 (2020-2021) periods, a decrease in the number of S. pyogenes isolates was observed with an increase in S. dysgalactiae subsp. equisimilis, while the resistance to macrolides found was higher for S. pyogenes and remained constant for S. dysgalactiae subsp. equisimilis. The identification of the etiologic agent and determination of antibiotic sensitivity are important for epidemiological surveillance of macrolide resistance, as they are a treatment option in patients who are allergic to ß-lactams (AU)

Detección rápida de antígenos de Streptococcus pyogenes en pacientes de 0 a 14 años asistidos en dos servicios de urgencia pediátrica (14/2/2018-13/4/2018) / Rapid detection of Streptococcus pyogenes' antigens in patients of 0 to 14 years of age, assisted in two pediatric emergency wards (2/14/2018-4/13/2018) / Detecção rápida de antígenos de Streptococcus pyogenes em pacientes de 0 a 14 anos de idade assistidos por emergência pediátrica (14/2/2018-13/4/2018)

Introducción: las infecciones estreptocócicas pueden presentarse con fiebre, inflamación faringoamigdalina con o sin exudados, petequias en el paladar, adenitis cervical, exantema escarlatiniforme y / o dolor abdominal. Resulta útil en área de urgencia disponer de pruebas de detección rápida de antígenos de S. pyogenes (DRASP) de alta especificidad y sensibilidad algo menor. Objetivos: conocer la utilidad de un test de DRASP en 2 servicios de Urgencia Pediátrica, describiendo las características clínicas y epidemiológicas de los pacientes estudiados durante el período de la investigación y su correlación con el cultivo de exudado faríngeo mediante el cálculo de sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y valor predictivo negativo (VPN). Material y métodos: estudio prospectivo, observacional, transversal en dos servicios de emergencia pediátrica. Se incluyeron niños a los que se les realizó DRASP y exudado faríngeo (EF) entre el 14 de febrero y el 13 de abril de 2018. Se registró: sexo, edad, motivo de consulta, diagnóstico, tratamiento, destino, resultado del test y de cultivo faríngeo. Se calcularon S, E, VPP y VPN. Resultados: n=241 niños. Rango 8 meses - 14 años, media 6 años. Consultaron por fiebre 103 niños (42,7%); por odinofagia 48, por erupción 11 y 47 por otros síntomas. Al 95% de los niños se le otorgó el alta. DRASP negativos 87,6% (N: 211) y positivos 12,9% (N: 31). EF negativos 80,1% (n: 193) y positivos para SßHGA en 13,7% (n: 33). La sensibilidad de la prueba fue del 52% y su especificidad del 93%. El VPP 55% y el negativo 92%. El diagnóstico más frecuente fue faringitis viral 132 (54,7%). Conclusiones: el test se aplicó fundamentalmente a escolares febriles, algunos con odinofagia. Contribuye a diferenciar en forma rápida la etiología y habilita a no usar antibióticos en caso de resultado negativo. Estos resultados avalan el uso de DRASP en la urgencia pediátrica.

Introduction: streptococcal infections can show fever, pharyngotonsillar inflammation with or without swabs, palatal petechiae, cervical adenitis, scarlatiniform rash and/or abdominal pain. Rapid detection tests for S. pyogenes antigens (DRASP) with high specificity and somewhat lower sensitivity are a useful at the Emergency Ward. Objectives: know the usefulness of a DRASP test in 2 Pediatric Emergency, describe the clinical and epidemiological characteristics of the patients studied during the research period and its correlation with the culture of pharyngeal exudates by calculating sensitivity (S) , specificity (S), positive predictive value (PPV), and negative predictive value (NPV). Material and Methods: prospective, observational, cross-sectional study carried out in two pediatric emergency wards. We included children who underwent DRASP and pharyngeal swab (PS) between February 14 and April 13, 2018. The following data were recorded: sex, age, reason for consultation, diagnosis, treatment, destination, test results and throat cultures. S, S, PPV and NPV were calculated. Results: n=241 children. Range 8 months - 14 years, average 6 years. 103 children (42.7%) consulted due to fever; 48 due to sore throat, 11 due to rash and 47 due to other symptoms. 95% of children were discharged. DRASP negative 87.6% (N: 211) and positive 12.9% (N: 31). Negative EP 80.1% (n: 193) and positive for SßHGA in 13.7% (n: 33). The test sensitivity was 52% and specificity 93%. The PPV 55% and the negative 92%. The most frequent diagnosis was viral pharyngitis 132 (54.7%). Conclusions: the test was applied mainly to febrile schoolchildren, some with odynophagia. A quick etiology differentiation is helpful, since it prevents antibiotics from being used in the event of a negative result. These results support the use of DRASP in pediatric emergency wards.

Introdução: as infecções estreptocócicas manifestam-se com febre, inflamação faringotonsilar com ou sem exsudado, petéquias palatinas, adenite cervical, erupção cutânea escarlatiniforme e/ou dor abdominal. Nos serviços de emergência é útil realizar testes de detecção rápida para antígenos de S. pyogenes (DRASP) com alta especificidade e sensibilidade um pouco mais baixa Objetivos: conhecer a utilidade do teste DRASP em 2 Emergências Pediátricas, descrever as características clínicas e epidemiológicas dos pacientes estudados durante o período da pesquisa e sua correlação com a cultura de exsudatos faríngeos por meio do cálculo de sensibilidade (S) , especificidade (S), positivo valor preditivo (VPP) e valor preditivo negativo (VPN). Material e métodos: estudo prospectivo, observacional, transversal, realizado em duas unidades de emergência pediátrica. Foram incluídas crianças que realizaram DRASP e swab faríngeo (PS) entre 14 de fevereiro e 13 de abril de 2018. Foram registrados os seguintes dados: sexo, idade, motivo da consulta, diagnóstico, tratamento, destino, resultados de exames e culturas de garganta. S, S, VPP e VPN foram calculados. Resultados: n=241 crianças. Faixa 8 meses - 14 anos, média 6 anos. 103 crianças (42,7%) consultadas por febre; 48 por dor de garganta, 11 por erupção cutânea e 47 por outros sintomas. 95% das crianças receberam alta. DRASP negativo 87,6% (N: 211) e positivo 12,9% (N: 31). EP negativo 80,1% (n: 193) e positivo para SßHGA em 13,7% (n: 33). A sensibilidade do teste foi de 52% e a especificidade de 93%. O PPV 55% e o negativo 92%. O diagnóstico mais frequente foi faringite viral 132 (54,7%). Conclusões: o teste foi aplicado principalmente em escolares febris, alguns com odinofagia. A rápida diferenciação etiológica é útil, pois evita o uso de antibióticos em caso de resultado negativo. Esses resultados apoiam o uso do DRASP em enfermarias de emergência pediátrica.

Fatal Pediatric Streptococcal Infection: A Clinico-Pathological Study.

PURPOSE AND CONTEXT: Streptococcal Infection (SI) is an important cause of pediatric death in children, yet limited reports exist on autopsy findings in fatal SI cases. METHOD: Case records (1997-2019) of SI with no pre-existing risk factors were reviewed and selected. Their clinical and pathological findings in the autopsy reports were analyzed. RESULTS: In our cohort of 38 cases based on bacterial culture results, SI was most commonly caused by Streptococcus pneumoniae (SPn; 45%) and Streptococcus pyogenes (SPy; 37%). 92% of decedents had some prodromal symptoms prior to terminal presentation. The clinical course was often rapid, with 89% found unresponsive, suddenly collapsing, or dying within 24 hours of hospital admission. 64% of deaths were attributed to sepsis, more frequently diagnosed in the SPy group than in the SPn group (71% vs 48%). Pneumonia was found in both SPn and SPy groups, whereas meningitis was exclusively associated with SPn. CONCLUSION: Our study shows fatal SI is most commonly caused by either SPn or SPy, both of which are frequently associated with prodromal symptoms, rapid terminal clinical course, and evidence of sepsis. Postmortem diagnosis of sepsis is challenging and should be correlated with clinical features, bacterial culture results, and autopsy findings.

Pediatric deep neck infections: Clinical description and analysis of therapeutic management.

OBJECTIVES: The aim of our study was to describe clinical presentations, bacteriological results, and therapeutic management in a pediatric population presenting with acute pharyngeal suppuration. A further aim was to identify clinical, bacteriological, and radiological predictors of success associated with exclusive medical treatment. METHOD: A retrospective study was carried out including patients under 18 years of age hospitalized between January 1, 2015 and December 31, 2017 in our center for acute pharyngeal suppuration. We identified three groups of patients: group A, treated with exclusive intravenous antibiotics; group B, surgically treated after 48 h of appropriate antibiotic therapy, due to persistent fever and/or clinical worsening and/or persistence of a collection on follow-up imaging; group C, surgically treated as first-line therapy in association with intravenous antibiotics. A total of 83 patients were included: 36 in group A, 12 in group B, and 35 in group C. These three groups were compared for several variables: age of the patients, polynuclear neutrophil counts, diameter of the collections (the largest diameter found on imaging), duration of antibiotic therapy, delay before return to apyrexia, and hospitalization duration. RESULTS: A neck mass and torticollis were present, respectively, in 48.8 and 47.6% of cases. No breathing difficulties were reported. Streptococcus pyogenes was the most frequently identified microorganism. The average diameter of the collections from patients treated surgically as first-line therapy (group C) was significantly larger than that of the patients treated with antibiotics (group A) (27.89 mm vs. 18.73 mm, respectively, p = 0.0006). All the patients who required surgery despite 48 h of appropriate antibiotic therapy (group B) had collections with diameters greater than or equal to 15 mm. There was no significant difference between the groups concerning hospitalization duration. CONCLUSION: Exclusive medical treatment is associated with a high cure rate, mainly for collections with small diameter. We recommend special attention to patients treated with first-line exclusive intravenous antibiotic therapy and with a collection diameter greater than or equal to 15 mm.

Enfermedad invasiva por Streptococcus pyogenes con celulitis de manos bilateral: A propósito de un caso / Invasive Streptococcus pyogenes disease with bilateral cellulitis of the hands: A case report

El Streptococcus pyogenes o estreptococo B hemolítico Grupo A (EßHGA) suele ser una causa poco habitual de enfermedad invasiva en pediatría, la cual ha presentado un aumento en su incidencia en los últimos años. Se define como cualquier infección asociada al aislamiento de dicha bacteria de un sitio normalmente estéril y cuya presentación más frecuente es la bacteriemia. Los pacientes con EßHGA habitualmente se presentan con un sindrome febril asociado a manifestaciones clínicas relacionadas con el sitio primario de infección. Se presenta el caso de una paciente de 10 años, sin comorbilidades, que desarrolló enfermedad invasiva por EßHGA con bacteriemia e impacto secundario de piel y partes blandas resultando en una celulitis de manos bilateral

Streptococcus pyogenes or Group A Streptococcus (GAS) is an infrequent cause of invasive disease in pediatrics. Its incidence has increased in the last few years. It is defined as any infection associated with the isolation of GAS in a normally sterile site and its most frequent presentation is bacteremia. Patients with GAS bacteremia usually present with a febrile syndrome associated with clinical manifestations related to the primary site of infection. We present the case of a previously healthy, 10-year-old patient, who developed an invasive disease due to GAS with bacteremia and secondary impact of skin and soft tissues that developed in bilateral cellulitis of the hands

Molecular characterisation of group A streptococcus isolates recovered from the north-west of Pretoria, South Africa.

BACKGROUND: Group A streptococcus (GAS) is a human pathogen responsible for a wide range of invasive and non-invasive infections. Pharyngitis caused by GAS may have complications such as acute rheumatic fever subsequently leading to rheumatic heart disease (RHD). RHD continues to have high morbidity and mortality and affects millions of children and young adults, mostly in developing countries. An effective preventive vaccine against GAS may reduce the morbidity and mortality. A 30-valent M-protein-based vaccine is currently at the clinical trials stage of development. Potential vaccine coverage will depend on the geographical distribution of GAS emm (M protein) types. OBJECTIVES: To determine the emm types of GAS isolates circulating in the north-west of Pretoria, South Africa. METHODS: Throat swabs were collected from patients aged 3 - 20 years presenting with pharyngitis at one local clinic. In addition, GAS clinical isolates were collected from the National Health Laboratory Service diagnostic laboratory. Emm genotyping was done on the GAS isolates by amplification of the emm gene followed by sequencing of the 5' portion of the gene. The emm types were correlated with the types in the vaccine. RESULTS: A total of 54 GAS isolates were collected, comprising 19 pharyngitis and 35 clinical isolates. We found 15 different emm types among the 43 GAS isolates that were successfully sequenced. Eleven isolates (20%) could not be typed. The most prevalent emm type was 92 (26%), which is part of the 30-valent vaccine. This was followed by emm 25 and 75, each accounting for 12% of the isolates. Up to 67% of the emm types are not covered in the 30-valent vaccine. CONCLUSIONS: Fifteen emm types were identified, of which 92 was the most prevalent. It is concerning that 67% of the emm types are not covered in the vaccine currently under development. It is recommended that surveillance studies be extended to include other parts of the country in order to expand knowledge of the circulating emm types.

High prevalence of pharyngeal bacterial pathogens among healthy adolescents and young adults.

The pharyngeal mucosa can be colonized with bacteria that have potential to cause pharyngotonsillitis. By the use of culturing techniques and PCR, we aimed to assess the prevalence of bacterial pharyngeal pathogens among healthy adolescents and young adults. We performed a cross-sectional study in a community-based cohort of 217 healthy individuals between 16 and 25 years of age. Samples were analyzed for Group A streptococci (GAS), Group C/G streptococci (SDSE), Fusobacterium necrophorum, and Arcanobacterium haemolyticum. Compared to culturing, the PCR method resulted in more frequent detection, albeit in most cases with low levels of DNA, of GAS (20/217 vs. 5/217; p < 0.01) and F. necrophorum (20/217 vs. 8/217; p < 0.01). Culturing and PCR yielded similar rates of SDSE detection (14/217 vs. 12/217; p = 0.73). Arcanobacterium haemolyticum was rarely detected (3/217), and only by PCR. Overall, in 25.3% (55/217) of these healthy adolescents and young adults at least one of these pathogens was detected, a rate that is higher than previously described. Further studies are needed before clinical adoption of PCR-based detection methods for pharyngeal bacterial pathogens, as our findings suggest a high incidence of asymptomatic carriage among adolescents and young adults without throat infections.

Effect of erythritol and xylitol on Streptococcus pyogenes causing peritonsillar abscesses.

Polyols are effective against caries-causing streptococci but the effect on oropharynx-derived pyogenic streptococci is not well characterised. We aimed to study the effect of erythritol (ERY) and xylitol (XYL) against Streptococcus pyogenes isolated from peritonsillar abscesses (PTA). We used 31 clinical isolates and 5 throat culture collection strains. Inhibition of bacterial growth by polyols at 2.5%, 5% and 10% concentrations was studied and the results were scored. Amylase levels in PTA pus were compared to polyol effectivity scores (PES). Growth curves of four S. pyogenes isolates were analysed. Our study showed that XYL was more effective than ERY inhibiting 71-97% and 48-84% of isolates, respectively, depending of concentrations. 48% of clinical and all throat strains were inhibited by polyols in all concentrations (PES 3). PES was negative or zero in 26% of the isolates in the presence of ERY and in 19% of XYL. ERY enhanced the growth of S. pyogenes isolated from pus with high amylase levels. Polyols in all concentrations inhibited the growth in exponential phase. In conclusion, ERY and XYL are potent growth inhibitors of S. pyogenes isolated from PTA. Therefore, ERY and XYL may have potential in preventing PTA in the patients with frequent tonsillitis episodes.

Global patterns of necrotizing soft tissue infections: A systematic review and meta-analysis.

BACKGROUND: Frequency, microbiology, and outcomes of necrotizing soft tissue infections vary based on locoregional and environmental factors; however, there has been no global survey of these patterns. We performed a systematic review/meta-analysis on published reports of necrotizing soft tissue infections from across the globe. METHODS: Peer-reviewed empirical studies examining rates of polymicrobial and monomicrobial necrotizing soft tissue infections with microbial isolation and overall mortality rate were extracted along with geographic location using PubMed, Scopus, ProQuest, and Web of Science. Random-effects meta-analyses and sensitivity analyses were performed, adjusting for publication bias. Meta-regression analyses examined moderator effects of risk factors. RESULTS: One hundred and five studies (8,718 total patients) were included. Pooled prevalence of polymicrobial and monomicrobial infections were 53% and 37.9%, respectively. Truncal necrotizing soft tissue infections were commonly polymicrobial (P < .001), whereas monomicrobial infections prevailed in extremities (P = .008). Global prevalence of monomicrobial necrotizing soft tissue infections was observed to increase by 1.1% annually (P = .003). Staphylococcus aureus was the most common organism globally and in North America, Asia, the Middle East, and Africa, followed by Streptococcus pyogenes and Escherichia coli. Methicillin-resistant S. aureus accounted for 16% of necrotizing soft tissue infections globally. Overall mortality was 23.1%, observed to decline globally over the last decade (P = .020). No regional differences were noted for mortality. CONCLUSION: Although polymicrobial infections remain predominant worldwide, the incidence of monomicrobial infections is increasing. The observed decline in necrotizing soft tissue infection-related mortality is encouraging and may reflect advances in management, despite major variations in available healthcare resources globally.

The Indirect Impact of the SARS-CoV-2 Pandemic on Invasive Group a Streptococcus, Streptococcus Pneumoniae and Staphylococcus Aureus Infections in Houston Area Children.

Masking and social distancing have been adopted to mitigate the severe acute respiratory syndrome coronavirus 2 pandemic. We evaluated the indirect impact of severe acute respiratory syndrome coronavirus 2 prevention strategies on invasive Staphylococcus aureus, Streptococcus pneumoniae (pneumococcus) and Group A Streptococcus in Houston area children. We observed a decline in invasive pneumococcal disease and invasive Group A Streptococcus temporally associated with social distancing/masking/school closures.

A 70-Year-Old Man With Conspicuous Thigh Pain and ST-Segment Elevations.

CASE PRESENTATION: A 70-year-old man presented to the ED with sudden onset of left thigh pain followed by transient chest discomfort. His history included cerebrovascular disease, hypertension, and cocaine and methamphetamine use. Physical examination revealed an uncomfortable male subject with a temperature of 37 °C, heart rate of 129 beats/min, BP of 130/65 mm Hg, and 98% oxygen saturation on room air. There was point tenderness in the left lateral thigh without erythema, swelling, or overlying skin changes. His cardiac examination revealed an irregular tachycardia at 129 beats/min and normal first and second heart sounds without murmurs, gallops, or rubs. The remainder of the examination was unremarkable.

Synergistic effects of Cu-doped ZnO nanoantibiotic against Gram-positive bacterial strains.

A viable hydrothermal technique has been explored for the synthesis of copper doped Zinc oxide nanoparticles (Cu-doped ZnO-NPs) based on the precursor's mixture of Copper-II chloride dihydrate (CuCl2.2H2O), Zinc chloride (ZnCl2), and potassium hydroxide (KOH). X-ray diffraction (XRD) reported the hexagonal wurtzite structure of the synthesized Cu-doped ZnO-NPs. The surface morphology is checked via field emission scanning electron microscopy (FE-SEM), whereas, the elemental compositions of the samples were confirmed by Raman, and X-ray photoelectron spectroscopy (XPS), respectively. The as-obtained ZnO-NPs and Cu-doped ZnO-NPs were then tested for their antibacterial activity against clinical isolates of Gram-positive (Staphylococcus aureus, Streptococcus pyogenes) and Gram-negative (Escherichia coli, Klebsiella pneumonia) bacteria via agar well diffusion method. The zone of inhibition (ZOI) for Cu-doped ZnO-NPs was found to be 24 and 19 mm against S. Aureus and S. pyogenes, and 18 and 11 mm against E. coli and K. pneumoniae, respectively. The synthesized Cu-doped ZnO-NPs can thus be found as a potential nano antibiotic against Gram-positive multi-drug resistant bacterial strains.

Invasive Streptococcus pyogenes disease in Spain: a microbiological and epidemiological study covering the period 2007-2019.

The aim of this study is to present the first nationwide microbiological and epidemiological study of invasive group A Streptococcus (iGAS) disease in Spain. One thousand eight hundred ninety-three iGAS isolates were analyzed over 2007-2019. emm typing was performed by sequencing the gene's variable 5' end, exotoxin genes were identified by PCR, and antimicrobial susceptibility explored via the E test and disk diffusion. Five hundred twenty-three isolates were associated with sepsis, 292 with cellulitis, 232 with scarlet fever, 153 with pneumonia, 141 with streptococcal toxic shock syndrome, and 94 with necrotizing fasciitis. The most prevalent emm types were emm1 (449/1893 isolates), emm89 (210/1893), emm3 (208/1893), emm4 (150/1893), emm12 (112/1893) emm6 (107/1893), emm87 (89/1893), emm28 (88/1893), emm75 (78/1893), emm77 (78/1893), emm11 (58/1893), and emm22 (35/1893). emm1, emm3, emm4, and emm6 were the predominant types affecting children (mostly respiratory infections), while emm11, emm77, and emm89 prevailed in the elderly (mostly skin infections). Each emm type was associated with one or more exotoxin gene (spe, sme, and ssa) profiles. speA was detected in 660 isolates, speB in 1829, speC in 1014, speF in 1826, speG in 1651, speJ in 716, speH in 331, smeZ in 720, and ssa in 512. Isolates with speA were associated with the most severe infections. Penicillin susceptibility was universal. Two hundred twenty-four isolates were resistant to tetracycline, 169 to erythromycin, and 81 to clindamycin. Tetracycline, erythromycin, and clindamycin resistance rates declined over the study period. The above information could serve as the basis for continued surveillance efforts designed to control disease cause by this bacterium.

An emm-type specific qPCR to track bacterial load during experimental human Streptococcus pyogenes pharyngitis.

BACKGROUND: Streptococcus pyogenes causes a profound global burden of morbidity and mortality across its diverse clinical spectrum. To support a new controlled human infection ('challenge') model seeking to accelerate S. pyogenes vaccine development, we aimed to develop an accurate and reliable molecular method for quantifying bacterial load from pharyngeal swabs collected during experimental human pharyngitis. METHODS: Combined sequential RNA + DNA extraction from throat swabs was compared to traditional separate RNA-only and DNA-only extractions. An emm-type specific qPCR was developed to detect the emm75 challenge strain. Results from the qPCR were compared to culture, using throat swab samples collected in a human challenge study. RESULTS: The qPCR was 100% specific for the emm75 challenge strain when tested against a panel of S. pyogenes emm-types and other respiratory pathogens. Combined RNA + DNA extraction had similar yield to traditional separate extractions. The combined extraction method and emm75 qPCR had 98.8% sensitivity compared to culture for throat swabs collected from challenge study participants. CONCLUSIONS: We have developed a reliable molecular method for measuring S. pyogenes bacterial load from throat swabs collected in a controlled human infection model of S. pyogenes pharyngitis. TRIAL REGISTRATION: NCT03361163 on 4th December 2017.

Study of Normal Flora in the Pharynx of Healthy Children.

To improve our current understanding of normal flora in children, we investigated bacterial isolates from the pharynx and nasopharynx of 173 and 233 healthy children, respectively. The bacterial isolation rates were compared among three age groups: infants (<1 year), toddlers (1-5 years), and school-aged children (6-15 years). Gram-positive cocci were the predominant bacteria in the pharynx (Streptococcus mitis/oralis, 87.3%; Streptococcus salivarius, 54.3%; Rothia mucilaginosa, 41.6%; Staphylococcus aureus, 39.3%). Among infants, S. salivarius and Neisseria subflava, which are related to the development of teeth, were significantly lower than in the other age groups (P <0.0001, S. salivarius; P <0.01, N. subflava). With the exception of Corynebacterium pseudodiphtheriticum (44.2%, gram-positive rods), gram-negative rods largely predominated the nasopharynx (Moraxella catarrhalis, 32.1%; Moraxella nonliquefaciens, 28.3%). Among toddlers, M. catarrhalis and Streptococcus pneumoniae, which are the most common pathogens in acute otitis media, were significantly higher than in the infant group (P <0.05). Among the bacterial species implicated in pediatric respiratory infections, Streptococcus pyogenes was isolated in 3.5% of the pharyngeal samples. S. pneumoniae and Haemophilus influenzae were isolated in 22.3% and 17.2% of the nasopharyngeal samples, respectively. In conclusion, the normal flora of the respiratory tract differs not only by the sampling site but also by the age group.

Comparative genome analysis of three Group A Streptococcus dysgalactiae subsp. equisimilis strains isolated in Japan.

Introduction. Streptococcus dysgalactiae subsp. equisimilis (SDSE) is a ß-hemolytic streptococcus that causes severe invasive streptococcal infections, especially in the elderly and people with underlying diseases. SDSE strains are primarily characterized by Lancefield group G or C antigens.Hypothesis/Gap Statement. We have previously reported the prevalence of Lancefield group A SDSE (GA-SDSE) strains in Japan and have analysed the draft genome sequences of these strains. As GA-SDSE is a rare type of SDSE, only one complete genome has been sequenced to date.Aim. The present study is focused on genetic characteristics of GA-SDSE strains. In order to examine molecular characteristics, we also tested growth inhibition of other streptococci by GA-SDSE.Methodology. We determined the complete genome sequences of three GA-SDSE strains by two new generation sequencing systems (short-read and long-read sequencing data). Using the sequences, we also conducted a comparative analysis of GA-SDSE and group C/G SDSE strains. In addition, we tested multiplex and quantitative PCRs targeting the GA-SDSE, group G SDSE, and S. pyogenes.Results. We found a group-specific conserved region in GA-SDSE strains that is composed of genes encoding predicted anti-bacteriocin and streptococcal lantibiotic (Sal) proteins. Multiplex and quantitative PCRs targeting the GA-SDSE-specific region were able to distinguish between GA-SDSE, other SDSE, and S. pyogenes strains. The growth of GA-SDSE was suppressed in the presence of group G SDSE, indicating a possible explanation for the low frequency of isolation of GA-SDSE.Conclusion. The comparative genome analysis shows that the genome of GA-SDSE has a distinct arrangement, enabling the differentiation between S. pyogenes, GA-SDSE, and other SDSE strains using our PCR methods.