A 6-year review of acute post-streptococcal glomerulonephritis at a public children's hospital in Cape Town, South Africa.

BACKGROUND: Acute post-streptococcal glomerulonephritis (APSGN) is the most common cause of acute nephritis in children globally and, in some cases, may be associated with progressive kidney injury and failure, cumulating in the need for long-term dialysis and/or kidney transplantation. METHODS: Our retrospective study describes the occurrence of APSGN among children (< 14 years) admitted to a tertiary children's hospital in Cape Town, South Africa, from January 2015 to December 2020. RESULTS: Of 161 children who presented with acute nephritis (haematuria, oedema, oliguria, and hypertension), 100 met the inclusion criteria. Demographic, clinical features, laboratory findings, management, and outcome data were collected. APSGN was defined by the clinical presentation of at least two clinical signs of acute nephritis, and low serum complement 3 (C3) level or evidence of a recent streptococcal infection. Most cases of APSGN were associated with streptococcal skin infections: 55/100 (55%); 10/100 (10%) children presented with hypertensive seizures; C3 levels were low in 86/92 (93.5%) children; 94/94 (100%) children had elevated anti-deoxyribonuclease-B (anti-DNase-B) levels; and 80/94 (85%) also had elevated anti-streptolysin O titre (ASOT) at presentation. Eleven (11%) children had a percutaneous kidney biopsy; 4/11 (36%) showed histological features of post-infectious nephritis, and 7/11(64%) also had crescentic glomerulonephritis with immune complex deposits. Sixty-two (62%) children confirmed recovered, and five (5%) progressed to kidney failure, but 29 presumed recovered as they did not return for follow-up to our institution. CONCLUSIONS: Childhood APSGN remains an important health problem in South Africa (SA) with favourable outcomes in most, apart from those with crescentic glomerulonephritis who progressed to kidney failure.

Associations Between Findings of Fusobacterium necrophorum or ß-Hemolytic Streptococci and Complications in Pharyngotonsillitis-A Registry-Based Study in Southern Sweden.

BACKGROUND: Most pharyngotonsillitis guidelines focus on the identification of group A streptococci (GAS), guided by clinical scores determining whom to test with a rapid antigen detection test. Nevertheless, many patients testing negative with this test are evaluated for group C/G streptococci (GCS/GGS) and Fusobacterium necrophorum, yet their importance remains debated. Our primary aim was to evaluate associations between complications and findings of F. necrophorum, GAS, or GCS/GGS in pharyngotonsillitis. METHODS: This was a retrospective, registry-based study of pharyngotonsillitis cases tested for F. necrophorum (polymerase chain reaction) and ß-hemolytic streptococci (culture) in the Skåne Region, Sweden, in 2013-2020. Patients with prior complications or antibiotics (within 30 days) were excluded. Data were retrieved from registries and electronic charts. Logistic regression analyses were performed with a dichotomous composite outcome of complications as primary outcome, based on International Classification of Diseases, Tenth Revision, codes. Cases with negative results (polymerase chain reaction and culture) were set as reference category. Complications within 30 days were defined as peritonsillar or pharyngeal abscess, otitis, sinusitis, sepsis or septic complications, recurrence of pharyngotonsillitis (after 15-30 days) or hospitalization. RESULTS: Of 3700 registered cases, 28% had F. necrophorum, 13% had GCS/GGS, 10% had GAS, and 54% had negative results. The 30-day complication rates were high (20%). F. necrophorum (odds ratio, 1.8; 95% confidence interval, 1.5-2.1) and GAS (1.9; 1.5-2.5) were positively associated with complications, whereas GCS/GGS were negatively associated (0.7; 0.4-0.98). CONCLUSIONS: Our results indicate that F. necrophorum is a relevant pathogen in pharyngotonsillitis, whereas the relevance of testing for GCS/GGS is questioned. However, which patient to test and treat for F. necrophorum remains to be defined.

Bactericidal effect of lascufloxacin on HEp-2 cell-internalized group A Streptococcus.

INTRODUCTION: Although amoxicillin (AMPC) is recommended as first-line therapy for acute pharyngotonsillitis caused by group A streptococci (GAS), it often fails to eradicate infections. Internalization and subsequent intracellular survival of GAS are considered major mechanisms for penicillin therapeutic failure. It is, therefore, desirable to administer drugs that exert bactericidal effects on extracellular and intracellular GAS. In this study, we aim to investigate the bactericidal effects of lascufloxacin (LSFX) on internalized GAS in HEp-2 cells. MATERIALS AND METHODS: The GAS strain M1 and clinical isolate strain #2 were used in this study. Following treatment of GAS-infected human pharyngeal carcinoma epithelial HEp-2 cells with LSFX or AMPC, internalized GAS cells were recovered. The concentrations of LSFX and AMPC were equivalent to 1 × and 2 × MIC for strain M1. Culture medium was used as a control. Time-lapse and fluorescence images of GAS invading HEp-2 cell were obtained. LIVE/DEAD fluorescence staining was used to confirm the viability of internalized GAS. RESULTS: LSFX significantly reduced the number of cell-internalized M1 and #2 GAS strains compared to the control (p < 0.01) in a dose-dependent manner. However, AMPC did not reduce this in both strains. Both live and dead intracellular GAS were confirmed in HEp-2 cells exposed to LSFX. In contrast, intracellular GAS survived in HEp-2 cells exposed to AMPC and in the control. CONCLUSION: LSFX elicits significant bactericidal effects on cell-internalized GAS, hence it may represent a potent therapeutic option for patients with acute pharyngotonsillitis in whom AMPC treatment has failed.

Retrospective study of group A Streptococcus oropharyngeal infection diagnosis using a rapid antigenic detection test in a paediatric population from the central region of Portugal.

Group A Streptococcus (GAS) is one of the most important agents of oropharyngeal infection. To avoid unnecessary antibiotic prescription, it is recommended the confirmation of GAS infection in pharyngeal swabs using culture or rapid antigen detection test (RADT). This study aimed to retrospectively analyse the incidence of GAS oropharyngeal infection, detected by RADT, in a paediatric population in the Centre of Portugal. Data was collected from the database of the Paediatric Hospital Emergency Department (ED) regarding patients admitted with symptoms suggesting acute pharyngitis, from January 2013 to December 2018, in a total of 18,304 cases. Among these, 130 clinical files were searched for symptoms, complications and additional visits to the ED. The results showed an average GAS infection prevalence of 33%, with seasonal variation. In preschool children, especially in patients less than 3 years old, where the guidelines do not routinely encourage RADT, GAS tonsillitis assumed an unexpected importance, with 731 positive tests in a total of 3128 cases. Scarlatiniform rash and oral cavity petechiae had significant correlation with streptococcal aetiology (p < 0.05). The statistical analysis also showed that different signs and symptoms assume different weights depending on the age group of the patient. The main conclusion is that the incidence of GAS infection in the studied population is higher than generally described in preschool children, suggesting the need for a more cautious approach to children under 3 years presenting acute pharyngitis, and that RADT in this age group would contribute to a decrease in the number of unnoticed cases.

The aetiology of pharyngotonsillitis in primary health care: a prospective observational study.

BACKGROUND: Few studies on pharyngotonsillitis have examined the clinical presentation of different aetiologies where pathogens have been detected using molecular methods. We aimed to assess how well clinical signs and symptoms can predict (1) the presence or absence of a broad range of viruses and bacteria, and (2) reconsultations for a sore throat or a complication. METHODS: In this descriptive observational prospective study in primary health care 220 patients aged 15-45 with suspected pharyngotonsillitis were sampled from nose, throat and blood and screened for 20 bacteria and viruses using polymerase chain reaction (PCR), culture and serology. Odds ratios (OR) and predictive values with 95% confidence intervals (CI) were used to show association between microbiological findings and clinical signs and symptoms. Patients were followed up after 3 months by reviewing electronic medical records. RESULTS: Both cough and coryza were more common in patients with only viruses (67%) than in patients with only bacteria (21%) (p < 0.001), whereas tonsillar coating was more common in patients with only bacteria (53%) than in patients with only viruses (29%) (p = 0.006). Tonsillar coating (adjusted OR 6.0; 95% CI 2.5-14) and a lack of cough (adjusted OR 3.5; 95% CI 1.5-8.0) were significantly associated with Streptococcus pyogenes (group A streptococci; GAS) and with any bacterial finding. A Centor score of 3-4 had a positive predictive value of 49% (95% CI 42-57) for GAS and 66% (95% CI 57-74) for any bacterial findings. The use of rapid antigen detection test for GAS increased the positive predictive value for this group to 93%. CONCLUSIONS: Signs and symptoms, both single and combined, were insufficient to rule in GAS or other pathogens. However, both cough and coryza were useful to rule out GAS. The results support the clinical approach of restricting rapid antigen detection testing to patients with 3-4 Centor criteria. The low carriage rate of bacteria among asymptomatic controls implied that most detections in patients represented a true infection.

Association between bacterial finding, antibiotic treatment and clinical course in patients with pharyngotonsillitis: a registry-based study in primary healthcare in Sweden.

BACKGROUND: The role of non-group A streptococci and Fusobacterium necrophorum in pharyngotonsillitis has been disputed and few prospective studies have evaluated the effect of antibiotic treatment. This study uses registry data to investigate the relation between antibiotic prescription for pharyngotonsillitis in primary healthcare and return visits for pharyngotonsillitis, complications, and tonsillectomy. METHODS: Retrospective data were extracted from the regional electronic medical record system in Kronoberg County, Sweden, for all patients diagnosed with pharyngotonsillitis between 2012 and 2016. From these data, two cohorts were formed: one based on rapid antigen detection tests (RADT) for group A streptococci (GAS) and one based on routine throat cultures for ß-haemolytic streptococci and F. necrophorum. The 90 days following the inclusion visit were assessed for new visits for pharyngotonsillitis, complications, and tonsillectomy, and related to bacterial aetiology and antibiotic prescriptions given at inclusion. RESULTS: In the RADT cohort (n = 13,781), antibiotic prescription for patients with a positive RADT for GAS was associated with fewer return visits for pharyngotonsillitis within 30 days compared with no prescription (8.7% vs. 12%; p = 0.02), but not with the complication rate within 30 days (1.5% vs. 1.8%; p = 0.7) or with the tonsillectomy rate within 90 days (0.27% vs. 0.26%; p = 1). In contrast, antibiotic prescription for patients with a negative RADT was associated with more return visits for pharyngotonsillitis within 30 days (9.7% vs. 7.0%; p = 0.01). In the culture cohort (n = 1 370), antibiotic prescription for patients with Streptococcus dysgalactiae ssp. equisimilis was associated with fewer return visits for pharyngotonsillitis within 30 days compared with no prescription (15% vs. 29%; p = 0.03). CONCLUSIONS: Antibiotic prescription was associated with fewer return visits for pharyngotonsillitis in patients with a positive RADT for GAS but with more return visits in patients with a negative RADT for GAS. There were no differences in purulent complications related to antibiotic prescription.

Infected aortic aneurysm caused by Streptococcus pyogenes: A case report.

We reported the case with infected abdominal aortic aneurysm (AAA) caused by Streptococcus (S.) pyogenes. A seventy-seven-year-old man, who had the history of uncontrolled diabetes mellitus (DM), complained fever and abdominal pain. Abdominal computed tomography scan revealed the aneurysm above common iliac artery with false lumen. On admission, laboratory tests found marked elevation of inflammatory biomarkers. Thereby the infected AAA was suspected and blood culture was taken. The administration of meropenem (MEPM) and daptomycin (DAP) was started. Next day he underwent abdominal aortic replacement with prosthetic graft and debridement because of persistent abdominal pain and the enlargement of aneurysm. S. pyogenes in blood culture samples was identified by Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry. Same result was obtained from the tissue samples of the resected AAA. Then the diagnosis of infected AAA caused by S. pyogenes was made. Since isolated S. pyogenes showed the susceptibility to antibiotics tested including penicillin, antibiotics were changed to ampicillin (ABPC) for the de-escalation of antibiotics. He had kept the administration of ABPC for 4 weeks and transferred to another hospital for the further treatment of DM. The aneurysms by S. pyogenes are extremely rare, but we should note that S. pyogenes could induce the aneurysms.

Nationwide study of mortality and survival in pregnancy-related streptococcal toxic shock syndrome.

AIM: Streptococcal toxic shock syndrome is associated with the highest infection-related maternal mortality rates. We conducted a comparative analysis of the background factors and treatment course between survivors and nonsurvivors to improve our understanding concerning the optimal initial treatment approach for this fulminant disease. METHODS: This retrospective observational study was conducted based on clinical data collected from two national organizations. Clinical data of patients who died or survived (i.e. background information, clinical course and treatment administered) were collected. RESULTS: Records of 13 dead and 15 surviving patients were collected and analyzed. No statistically significant differences were found between the groups regarding age, parity, season, gestational age or the patients' location at the onset of symptoms. After the initial symptom onset, the survivors received antibiotics more systematically during their first visit to a clinic (P = 0.006). More survivors had received treatment within 1 h of onset of fulminant disease (P = 0.069). The number of fetal deaths was significantly higher in the mortality group (P = 0.003), while the fetal survival number was higher in the group of maternal survivors (P = 0.055). Maternal survivors with nonspecific initial symptoms received early intervention when there was a family history of group A streptococcal infection or a positive rapid antigen test result. CONCLUSION: Intensive care, including systemic antibiotic administration, may contribute to maternal survival when administered immediately (within 1 h) after the fulminant streptococcal toxic shock syndrome onset. Eliciting a family history of streptococcal infection and conducting a rapid antigen test can identify the patients needing early intervention.

Long-term, single-center surveillance of non-invasive group A streptococcal (GAS) infections, emm types and emm clusters.

Group A streptococci (GAS) are among the most frequent pathogens in children. Many epidemiological studies focus on specific GAS infections (such as tonsillopharyngitis or invasive disease), on GAS carriers or on post-streptococcal sequelae. By comparison, reports on regional GAS characteristics, particularly circulating non-invasive GAS in Europe, are rare. In a monocentric study, all GAS isolated from pediatric patients at a tertiary care hospital over a 6-year period (2006-2012) were characterized. GAS emm types and clusters were determined. Associated patient data were analyzed. Five hundred sixty-six GAS strains were collected. GAS tonsillopharyngitis was most common (71.6%), followed by pyoderma (6.0%), otitis media (3.7%), perineal dermatitis (3.4%), and invasive infections (1.4%). Colonizing strains represented 13.6% of GAS. GAS emm12 was most prevalent among invasive and non-invasive isolates. Emm1, emm4, emm28, and emm89 were the most frequent non-invasive GAS strains. The emm E4 cluster was most common, followed by the A-C4, A-C3, and E1. Among the GAS infections, different emm types and clusters were identified, e.g., emm4 was more common among patients with scarlet fever. Three new emm subtypes were characterized: emm29.13, emm36.7, and emm75.5. This comprehensive review of a large, local GAS cohort points to the differences between and similarities among GAS genotypes and disease manifestations, while minimizing regional variations. Considerable deviation from previous epidemiological findings is described, especially regarding the frequent detection of emm1 and emm89 in non-invasive GAS infections. Periodic updates on molecular and epidemiological GAS characteristics are needed to track the multifaceted pathogenic potential of GAS.

Streptococcal inhibitor of complement (SIC) modulates fibrinolysis and enhances bacterial survival within fibrin clots.

Some strains of the bacterial pathogen Streptococcus pyogenes secrete protein SIC (streptococcal inhibitor of complement), including strains of the clinically relevant M1 serotype. SIC neutralizes the effect of a number of antimicrobial proteins/peptides and interferes with the function of the host complement system. Previous studies have shown that some S. pyogenes proteins bind and modulate coagulation and fibrinolysis factors, raising the possibility that SIC also may interfere with the activity of these factors. Here we show that SIC interacts with both human thrombin and plasminogen, key components of coagulation and fibrinolysis. We found that during clot formation, SIC binds fibrin through its central region and that SIC inhibits fibrinolysis by interacting with plasminogen. Flow cytometry results indicated that SIC and plasminogen bind simultaneously to S. pyogenes bacteria, and fluorescence microscopy revealed co-localization of the two proteins at the bacterial surface. As a consequence, SIC-expressing bacteria entrapped in clots inhibit fibrinolysis, leading to delayed bacterial escape from the clots as compared with mutant bacteria lacking SIC. Moreover, within the clots SIC-expressing bacteria were protected against killing. In an animal model of subcutaneous infection, SIC-expressing bacteria exhibited a delayed systemic spread. These results demonstrate that the bacterial protein SIC interferes with coagulation and fibrinolysis and thereby enhances bacterial survival, a finding that has significant implications for S. pyogenes virulence.

Biological Characterization and Inhibition of Streptococcus pyogenes ZUH1 Causing Chronic Cystitis by Crocus sativus Methanol Extract, Bee Honey Alone or in Combination with Antibiotics: An In Vitro Study.

Streptococcus pyogenes (S. pyogenes) ZUH1 was isolated and characterized using morphological, cultural and biochemical methods. The results showed that the marker genes (namely spyCEP, ssa, sic, sdaB and speG) indicating group A streptococci (GAS) were detected in the S. pyogenes genome. The results showed that the S. pyogenes strain was inhibited by Crocus sativus methanol extract (CSME), bee honey (BH) and catfish glycoprotein (CFG). The inhibitory activity of these natural agents were compared with standard antibiotics such as Ceftazidime (30 µg/mL), Cefoperazone (75 µg/mL), Cefoxitin (30 µg/mL) and Imipenem (10 µg/mL). There was a synergistic effect between certain antibiotics and CSME. GC-MS and IR analysis of CSME showed different cyclic ketones, aldehydes, esters, alcohols and acids. The main compounds were tetradecanoic acid, safranal and isophorone. Transmission electron microscopy (TEM) images of S. pyogenes cells treated with CSME showed signs of an irregular wrinkled outer surface, fragmentation, adhesion and aggregation of damaged bacterial cells or cellular debris. The marker genes (spyCEP, ssa, sic, sdaB and speG) could be used as a rapid diagnostic tool for GAS. CSME, BH and CFG showed distinctive anti-streptococcal activity either alone or in combinations with antibiotics; their action on S. pyogenes cells was studied by TEM. There was a synergistic effect between antibiotics and Crocus sativus, bee honey, and glycoprotein against S. pyogenes ZUH1. The action of natural agents on the pathogenic cells was shown using TEM.

Antimicrobial resistance in beta-haemolytic streptococci in India: A four-year study.

BACKGROUND & OBJECTIVES: The incidence and severity of invasive and non-invasive infections demonstrate variability over time. The emerging resistance of Group A streptococci (GAS) to commonly used antibiotics is of grave concern. This study was conducted to assess the antimicrobial resistance of beta-haemolytic streptococci (ßHS) in India and to ascertain the molecular mechanisms of resistance. METHODS: All isolates of ßHS from the Trauma Centre of All India Institute of Medical Sciences (AIIMS) (north India), and heavily populated area of old Delhi from 2010 to 2014 and Yashoda Hospital, Secunderabad (in south India, 2010-2012) and preserved isolates of ßHS at AIIMS (2005-2009) were included. Phenotypic confirmation was done using conventional methods and the Vitek 2. Antibiotic sensitivity testing was done by disc diffusion and E-test. Detection of resistance genes, erm(A), erm(B), mef(A), tet(M) and tet(O), was done by polymerase chain reaction (PCR). RESULTS: A total of 296 isolates of ßHS (240 from north and 21 from south India) were included in the study. Of the 296 ßHS, 220 (74%) were GAS, 52 (17.5%) were Group G streptococci and 11 (3.7%), 10 (3.3%) and three (1%) were Group B streptococci, Group C streptococci and Group F streptococci, respectively. A total of 102 (46%) and 174 (79%) isolates were resistant to tetracycline and erythromycin, respectively; a lower resistance to ciprofloxacin (21, 9.5%) was observed. A total of 42 (14%) and 30 (10%) isolates, respectively, were positive for tet(M) and erm(B) genes. Only 13 (5%) isolates were positive for mef(A). None of the isolates were positive for erm(A) and tet(O). There was discordance between the results of E-test and PCR for erythromycin and tetracycline. INTERPRETATION & CONCLUSIONS: A high level of resistance to erythromycin and tetracycline was seen in ßHS in India. Discordance between genotypic and phenotypic results was reported. Absence of erm(A) and tet(O) with high prevalence of tet(M) and erm(B) was observed.

Incremental Contributions of FbaA and Other Impetigo-Associated Surface Proteins to Fitness and Virulence of a Classical Group A Streptococcal Skin Strain.

Group A streptococci (GAS) are highly prevalent human pathogens whose primary ecological niche is the superficial epithelial layers of the throat and/or skin. Many GAS strains with a strong tendency to cause pharyngitis are distinct from strains that tend to cause impetigo; thus, genetic differences between them may confer host tissue-specific virulence. In this study, the FbaA surface protein gene was found to be present in most skin specialist strains but largely absent from a genetically related subset of pharyngitis isolates. In an ΔfbaA mutant constructed in the impetigo strain Alab49, loss of FbaA resulted in a slight but significant decrease in GAS fitness in a humanized mouse model of impetigo; the ΔfbaA mutant also exhibited decreased survival in whole human blood due to phagocytosis. In assays with highly sensitive outcome measures, Alab49ΔfbaA was compared to other isogenic mutants lacking virulence genes known to be disproportionately associated with classical skin strains. FbaA and PAM (i.e., the M53 protein) had additive effects in promoting GAS survival in whole blood. The pilus adhesin tip protein Cpa promoted Alab49 survival in whole blood and appears to fully account for the antiphagocytic effect attributable to pili. The finding that numerous skin strain-associated virulence factors make slight but significant contributions to virulence underscores the incremental contributions to fitness of individual surface protein genes and the multifactorial nature of GAS-host interactions.

Inhibition of streptococcal pyrogenic exotoxin B using allicin from garlic.

Streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococci (GAS) and inactivation of SpeB results in the significantly decreased virulence of the bacterium. The protein is secreted as an inactive zymogen of 40 KDa (SpeBz) and undergoes proteolytic truncation to result in a 28 KDa mature active protease (SpeBm). In this study the effect of allicin on the proteolytic activity of SpeBm was evaluated using azocasein assay. Allicin neutralized the SpeBm proteolytic activity in a concentration dependent manner (IC50 = 15.71 ± 0.45 µg/ml). The loss of activity was completely reversed by subsequent treatment with a reducing agent, dithiothreitol (DTT; 10 mM final concentration), suggesting that allicin likely inhibits the SpeBm by forming a disulfide linkage with an active thiol group in its active site. This mechanism of action was further confirmed with the fact that DTT did not reverse the SpeBm activity in the presence of E-64, a cysteine protease-specific inhibitor, which works specially by forming a thioether linkage with free sulfhydryl groups in enzymes active site. The MIC of allicin against GAS was found to be 32 µg/ml. Exposure of GAS culture to allicin (25 µg/ml) inhibited maturation of SpeBz to the SpeBm. In conclusion, the results of this study suggest that allicin inhibits the maturation of SpeBz and proteolytic activity of SpeBm and could be a potential therapeutic agent for the treatment of GAS infections.

Development of a fast and low-cost qPCR assay for diagnosis of acute gas pharyngitis.

BACKGROUND: Group A streptococci (GAS) are the most common bacterial cause of acute pharyngitis and account for 15-30 % of cases of acute pharyngitis in children and 5-10 % of cases in adults. In this study, a real-time quantitative PCR (qPCR) based GAS detection assay in pharyngeal swab specimens was developed. METHODS: The qPCR assay was compared with the gold standard bacterial culture and a rapid antigen detection test (RADT) to evaluate its clinical performance in 687 patients. The analytical sensitivity of the assay was 240 cfu/swab. Forty-five different potential cross-reacting organisms did not react with the test. Four different laboratories for the reproducibility studies were in 100 % (60/60) agreement for the contrived GAS positive and negative swab samples. RESULTS: The relative sensitivities of the RADT and the qPCR test were 55.9 and 100 %; and the relative specificities were 100 and 96.3 %, respectively. Duration of the total assay for 24 samples including pre-analytical processing and analysis changed between 42 and 55 min depending on the type of qPCR instrument used. A simple DNA extraction method and a low qPCR volume made the developed assay an economical alternative for the GAS detection. CONCLUSION: We showed that the developed qPCR test is rapid, cheap, sensitive and specific and therefore can be used to replace both antigen detection and culture for diagnosis of acute GAS pharyngitis.

Oropharyngeal group A streptococcal colonization disrupts latent Epstein-Barr virus infection.

Epstein-Barr virus (EBV) infects >90% of the human population within the first 2 decades of life and establishes reversible latent infection in B cells. The stimuli that lead to switching from latent to lytic EBV infection in vivo are still elusive. Group A streptococci (GAS) are a common cause of bacterial pharyngotonsillitis in children and adolescents and colonize the tonsils and pharynx of up to 20% of healthy children. Thus, concomitant presence of EBV and GAS in the same individual is frequent. Here, we show that EBV carriers who are colonized with GAS shed EBV particles in higher numbers in their saliva, compared with EBV carriers not colonized with GAS. Messenger RNA levels of the master lytic regulatory EBV gene BZLF1 were more frequently detected in tonsils from EBV carriers colonized with GAS than from EBV carriers not colonized. Heat-killed GAS, potentially mimicking GAS colonization, elicited lytic EBV in latently infected lymphoblastoid cell lines (LCLs) partially via Toll-like receptor 2 triggering, as did purified GAS peptidoglycan. Thus, colonization by GAS might benefit EBV by increasing the EBV load in saliva and thereby enhancing the likelihood of EBV spread to other hosts.

Characterization of group A streptococci causing invasive diseases in Sri Lanka.

Group A ß haemolytic streptococcus (GAS) or Streptococcus pyogenes is a human pathogen that causes an array of infections, including pharyngitis, cellulitis, impetigo, scarlet fever, toxic shock syndrome, and necrotizing fasciitis. The present study characterizes 51 GAS isolates from invasive infections in Sri Lanka, focusing on resistance profiles, genetic determinants of resistance, and virulence markers. Isolates were tested for sensitivity to penicillin, erythromycin, clindamycin, and tetracycline. The presence of erm(A), erm(B), and mef(A) was detected in erythromycin-resistant isolates, while tet(M) was detected in the tetracycline-resistant isolates. PCR was used to identify SpeA, SpeB, SpeC, SpeF, SpeG, smez, and ssa as virulence markers. Selected GAS isolates were emm-typed using the updated CDC protocol. All 51 isolates were susceptible to penicillin. The number of isolates non-susceptible to erythromycin was 16. The commonest resistance determinant identified was erm(B) (11/16). Tetracycline non-susceptibility was found in 36 (70.6 %) isolates and 26 of them contained the tet(M) gene. Thirteen (25.5 %) isolates were resistant to both tetracycline and erythromycin, while 12 (23.5 %) isolates were sensitive to both antibiotics. The commonest virulence markers detected among the isolates were SpeB (44, 86.3 %), SpeG (36, 70.6 %), and SpeF (35, 68.6 %), while SpeJ (15, 29.4 %), SpeA (10, 19.6 %), and ssa (5,9.8 %) were less common. The emm types were diverse. In conclusion, the GAS isolates studied showed resistance to erythromycin and tetracycline, while retaining universal susceptibility to penicillin. Additionally, these isolates exhibited diverse genetic backgrounds, displaying varying patterns of virulence genes and emm types.

Group A streptococcus isolated in Guyana with reduced susceptibility to ß-lactam antibiotics.

Introduction. Streptococcus pyogenes [group A streptococci (GAS)] is the causative agent of pharyngitis and various other syndromes involving cellulitis, streptococcal toxic shock syndrome (STSS), and necrotising fasciitis. Although the prevalence of GAS infections globally remains high, necessitating the widespread use of ß-lactam antibiotics, GAS have remained largely susceptible to these agents. However, there have been several reports of GAS with reduced susceptibility harbouring mutations in genes for penicillin-binding proteins (PBPs). The objectives of this study were to examine the in vitro ß-lactam susceptibility patterns of group A streptococci, determine the prevalence of drug resistance, and ascertain whether such resistance could be attributed to mutations in specific PBP genes. Methods. In this study, we sought to use Sanger sequencing to identify mutations in PBP genes of Streptococcus pyogenes isolated from patients that required inpatient and outpatient care that could confer reduced PBP affinity for penicillin and/or cephalosporin antibiotics. All isolates were screened for susceptibility to penicillin, amoxicillin, and cefazolin using E-test strips. Results. While there were no documented cases of reduced susceptibility to penicillin or amoxicillin, 13 isolates had reduced susceptibility to cefazolin. Examination of pbp1a by Sanger sequencing revealed several isolates with single amino acid substitutions, which could potentially reduce the affinity of PBP 1A for cefazolin and possibly other first-generation cephalosporins. Conclusion. Penicillin and penicillin-derived antibiotics remain effective treatment options for GAS infections, but active surveillance is needed to monitor for changes to susceptibility patterns against these and other antibiotics and understand the genetic mechanisms contributing to them.

Clinical and molecular epidemiological features of critically ill patients with invasive group A Streptococcus infections: a Belgian multicenter case-series.

BACKGROUND: Recent alerts have highlighted an increase in group A streptococcal (GAS) infections since 2022 in Europe and the United States. Streptococcus pyogenes can cause limited skin or mucosal disease, but can also present as severe invasive disease necessitating critical care. We performed a multicenter retrospective study of patients with GAS infections recently admitted to Belgian intensive care units (ICUs) since January 2022. We describe patient characteristics and investigate the molecular epidemiology of the S. pyogenes strains involved. RESULTS: Between January 2022 and May 2023, a total of 86 cases (56 adults, 30 children) with GAS disease were admitted to critical care in the university hospitals of Leuven, Antwerp and Liège. We noted a strikingly high incidence of severe community-acquired pneumonia (sCAP) (45% of adults, 77% of children) complicated with empyema in 45% and 83% of adult and pediatric cases, respectively. Two-thirds of patients with S. pyogenes pneumonia had viral co-infection, with influenza (13 adults, 5 children) predominating. Other disease presentations included necrotizing fasciitis (23% of adults), other severe skin/soft tissue infections (16% of adults, 13% of children) and ear/nose/throat infections (13% of adults, 13% of children). Cardiogenic shock was frequent (36% of adults, 20% of children). Fifty-six patients (65%) had toxic shock syndrome. Organ support requirements were high and included invasive mechanical ventilation (77% of adults, 50% of children), renal replacement therapy (29% of adults, 3% of children) and extracorporeal membrane oxygenation (20% of adults, 7% of children). Mortality was 21% in adults and 3% in children. Genomic analysis of S. pyogenes strains from 55 out of 86 patients showed a predominance of emm1 strains (73%), with a replacement of the M1global lineage by the toxigenic M1UK lineage (83% of emm1 strains were M1UK). CONCLUSIONS: The recent rise of severe GAS infections (2022-23) is associated with introduction of the M1UK lineage in Belgium, but other factors may be at play-including intense circulation of respiratory viruses and potentially an immune debt after the COVID pandemic. Importantly, critical care physicians should include S. pyogenes as causative pathogen in the differential diagnosis of sCAP.