Penicillin Failure in the Treatment of Streptococcal Pharyngo-Tonsillitis

Group A streptococcus isolated in Guyana with reduced susceptibility to β-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 β-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 β-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.

Group A Streptococcal Infections in Pediatric Age: Updates about a Re-Emerging Pathogen

Group A Streptococcus (GAS) presents a significant global health burden due to its diverse clinical manifestations ranging from mild infections to life-threatening invasive diseases. While historically stable, the incidence of GAS infections declined during the COVID-19 pandemic but resurged following the relaxation of preventive measures. Despite general responsiveness to β-lactam antibiotics, there remains an urgent need for a GAS vaccine due to its substantial global disease burden, particularly in low-resource settings. Vaccine development faces numerous challenges, including the extensive strain diversity, the lack of suitable animal models for testing, potential autoimmune complications, and the need for global distribution, while addressing socioeconomic disparities in vaccine access. Several vaccine candidates are in various stages of development, offering hope for effective prevention strategies in the future.

Prevalence and antibiotics susceptibility profiles of Streptococcus pyogenes among pediatric patients with acute pharyngitis at Felege Hiwot Comprehensive Specialized Hospital, Northwest Ethiopia

BACKGROUND

Streptococcus pyogenes (S. pyogenes) is a Gram positive bacterium which is a leading cause of pharyngitis, skin and soft tissue infection and post streptococcal syndromes. Due to lack of β-lactamase enzyme production, it was considered universally susceptible to penicillin group and later generation of β-lactam antibiotics. As such, empirical treatment was common which might leads to development of antibiotics resistance. Therefore, the aims of this study were to determine the prevalence, antibiotics susceptibility profile; and associated factors of S. pyogenes among pediatric patients with acute pharyngitis in Felege Hiwot Comprehensive Specialized Hospital (FHCSH), Northwest Ethiopia.

METHODS

Hospital based cross-sectional study was carried out on 154 pediatric patients, whose age ranged from 0 to 18 years old using consecutive convenient sampling technique from 1st February to 19th June 2020 at FHCSH. S. pyogenes were identified by throat swab culture on 5% sheep blood agar with an overnight incubation at 37 °C in candle jar containing 5% CO2. Gram stain, catalase test and bacitracin test were used to identify S. pyogenes. Then,the data were entered into EpiData version 3.1 and analyzed by SPSS version 20 software. Finally, stepwise, bivariable and multivariable logistic regressions were carried out for identifyying factors having significant ssociation (p<0.05) with  acute pharyngitis.  RESULTS: From the total throat swabs, 14 (9.1%) with (95% CI; 4.5-14.3) were culture positive for S. pyogenes. From these, all isolates were sensitive to penicillin and ampicillin. On the otherhand, 4 (35.7%), 4 (35.5%), 3 (21.4%), 2 (14.3%), 1 (7.1%), 7 (50.0%) and 1 (7.1%) isolates were resistant for ceftriaxone, vancomycin, erythromycin, tetracycline, chloramphenicol, clindamycin and levofloxacin, respectively. The presence of any smoker in home showed significant association with S. pyogenes acute pharyngitis. Furthermore, having tender lymphadenopathy and recurrence were clinical predictors for S. pyogenes acute pharyngitis (P < 0.05).

CONCLUSION

The prevalence of S. pyogenes was guaged at 9.1% which is considered as low prevalence. All S. pyogenes isolats remain sensitive to penicillin. However, resistance was reported to clindamycin 7 (50.0%), ceftriaxone 5 (35.7%) and erythromycin 3 (21.4%). The current practice of giving erythromycin, clindamycin instead of penicillin and ampicillin is againest the microbiology result. Therefore, current empirical treatment of acute pharyngitis shall take in to account the current evidences. Continuous surveillance of antibiotics resistance pattern of S. pyogenes for acute pharyngitis must be strengthen to improve the use of antibiotics in hospitals.

Survival Strategies of Streptococcus pyogenes in Response to Phage Infection

Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecycle, complete bacterial subpopulations are utilized as hosts for bacteriophage replication. However, during their lysogenic lifecycle, bacteriophages can integrate into the host chromosome and alter the host’s genomic make-up, possibly resulting in evolutionary important adjustments. Not surprisingly, bacteria have evolved sophisticated immune systems to protect against phage infection. Streptococcus pyogenes isolates are frequently lysogenic and their prophages have been shown to be major contributors to the virulence of this pathogen. Most S. pyogenes phage research has focused on genomic prophages in relation to virulence, but little is known about the defensive arsenal of S. pyogenes against lytic phage infection. Here, we characterized Phage A1, an S. pyogenes bacteriophage, and investigated several mechanisms that S. pyogenes utilizes to protect itself against phage predation. We show that Phage A1 belongs to the Siphoviridae family and contains a circular double-stranded DNA genome that follows a modular organization described for other streptococcal phages. After infection, the Phage A1 genome can be detected in isolated S. pyogenes survivor strains, which enables the survival of the bacterial host and Phage A1 resistance. Furthermore, we demonstrate that the type II-A CRISPR-Cas system of S. pyogenes acquires new spacers upon phage infection, which are increasingly detectable in the absence of a capsule. Lastly, we show that S. pyogenes produces membrane vesicles that bind to phages, thereby limiting the pool of phages available for infection. Altogether, this work provides novel insight into survival strategies employed by S. pyogenes to combat phage predation.

Group A Streptococcus Antibiotic Resistance in Iranian Children: A Meta-analysis

Objectives

Streptococcus pyogenes is associated with mild to severe infections, particularly in children and young adults. Proper antimicrobial treatment of S. pyogenes infections is important to prevent post-streptococcal complications. Therefore, the purpose of this meta-analysis was to evaluate the prevalence of S. pyogenes antibiotic resistance among Iranian children.

Methods

We identified all published studies up to 20 March 2019 related to S. pyogenes antibiotic resistance by searching Persian and English electronic databases. Search terms included S. pyogenes, children, and Iran. Out of 1022 publications, 12 articles were eligible and included based on the inclusion and exclusion criteria.

Results

Our analysis indicated the following prevalence pattern for S. pyogenes antimicrobial resistance in Iran: 4.2% to penicillin, 38.3% to amoxicillin, 5.4% to erythromycin, 12.0% to azithromycin, 12.6% to clarithromycin, 12.4% to clindamycin, 15.3% to rifampicin, 8.1% to ceftriaxone, 17.6% to cefixime, 36.9% to ampicillin, 14.1% to vancomycin, 8.4% to chloramphenicol, 30.4% to tetracycline, 8.8% to cefotaxime, 82.8% to trimethoprim/sulfamethoxazole, 39.6% to gentamicin, 11.9% to ofloxacin, 28.3% to carbenicillin, 3.1% to ciprofloxacin, 6.1% to imipenem, 18.2% to cephalothin, 57.6% to tobramycin, 49.3% to kanamycin, 79.0% to cloxacillin, 12.9% to cephalexin, 10.7% to cefazolin, and 89.5% to amoxicillin-clavulanic acid.

Conclusions

Our findings suggest penicillin (in non-allergic children) and macrolides, lincosamides, and narrow-spectrum cephalosporins (in penicillin-allergic children) as the treatments of choice in Iran.

Application of bacteriophage-derived endolysins to combat streptococcal disease: current state and perspectives

The decline in new antibiotic candidates combined with an increase in antibiotic-resistance necessitates development of alternative antimicrobials. Bacteriophage-encoded endolysins (lysins) are a class of peptidoglycan hydrolases that have been proposed to fill this antimicrobial void. The past 20 years has seen a dramatic expansion of studies on endolysin discovery, structure/function, engineering, immunogenicity, toxicity/safety, and efficacy in animal models. These collective efforts have led to current human clinical trials on at least three different endolysins that are antimicrobial toward staphylococcal species. It can be anticipated that endolysins targeting streptococcal species may be next in line for translational development. Notably, streptococcal diseases largely manifest at accessible mucous membranes, which should be beneficial for protein therapeutics. Additionally, there are a number of well-identified streptococcal diseases in both humans and animals that are associated with a single species, further favoring a targeted endolysin therapeutic.

Group A Streptococcal S Protein Utilizes Red Blood Cells as Immune Camouflage and Is a Critical Determinant for Immune Evasion

Group A Streptococcus (GAS) is a human-specific pathogen that evades the host immune response through the elaboration of multiple virulence factors. Although many of these factors have been studied, numerous proteins encoded by the GAS genome are of unknown function. Herein, we characterize a biomimetic red blood cell (RBC)-captured protein of unknown function—annotated subsequently as S protein—in GAS pathophysiology. S protein maintains the hydrophobic properties of GAS, and its absence reduces survival in human blood. S protein facilitates GAS coating with lysed RBCs to promote molecular mimicry, which increases virulence in vitro and in vivo. Proteomic profiling reveals that the removal of S protein from GAS alters cellular and extracellular protein landscapes and is accompanied by a decrease in the abundance of several key GAS virulence determinants. In vivo, the absence of S protein results in a striking attenuation of virulence and promotes a robust immune response and immunological memory.

Wierzbicki et al. show that S protein is a major group A Streptococcus (GAS) virulence factor that facilitates bacterial coating with lysed red blood cells to promote molecular mimicry, which increases virulence in vitro and in vivo. Removal of S protein reduces the abundance of multiple virulence factors and attenuates virulence.

Abundant Extractable Metabolites from Temperate Tree Barks: The Specific Antimicrobial Activity of Prunus Avium Extracts

Tree barks are mainly considered as wood wastes from forestry activities, but represent valuable resources as they may contain antimicrobial compounds. Here, we aimed to evaluate the possible antimicrobial activities of bark extracts and to characterize the chemical composition of the most active extract. Ten methanol bark extracts were tested in vitro against 17 bacterial strains and 5 yeast strains, through minimum inhibitory concentration (MIC) and minimum bactericidal (or fungicidal) concentration (MBC/MFC) assays. The extract from Prunus avium (E2-4) displayed the largest bactericidal activity against Gram-positive bacteria, with a lethal effect on 6 out of 8 strains. Antibiofilm assays of E2-4 were performed by crystal violet staining and enumeration of adhered bacteria. Assays demonstrated a biofilm inhibitory effect of E2-4 against Staphylococcus aureus CIP 53.154 at concentrations equal to or higher than 250 µg/mL. Chemical profiling of E2-4 by ¹³C nuclear magnetic resonance (NMR) revealed the presence of dihydrowogonin as a major constituent of the extract. E2-4 was fractionated by centrifugal partition chromatography and the three fractions containing dihydrowogonin were tested for their antibacterial and antibiofilm activities, revealing similar activities to those of E2-4. Dihydrowogonin was positively assessed as an interesting antimicrobial compound, which could be valued from wastes of Prunus avium barks.