Trends in Antimicrobial Resistance Patterns of Group A Streptococci, Molecular Basis and Implications

Antimicrobial resistance and epidemiological patterns of Streptococcus pyogenes in Türkiye

BACKGROUND

Drug-resistant Group A beta-hemolytic streptococci remain significant infectious agents globally. This study investigated the major S. pyogenes strains responsible for infections in Türkiye and their susceptibility to beta-lactam and macrolide antibiotics.

METHODS

We determined the minimum inhibitory concentration using the penicillin gradient test and performed emm typing and DNA fingerprinting via pulsed-field gel electrophoresis (PFGE) to analyze the clonal spread of 92 S. pyogenes strains isolated from two hospitals in Türkiye between 2020 and 2022.

RESULTS

Our findings revealed the predominant S. pyogenes strains causing infections in the population and provided insights into the epidemiological relatedness of these drug-resistant strains. This study also evaluated the correlation between emm typing and PFGE in tracking S. pyogenes epidemiology. In this study, the current resistance patterns of S. pyogenes strains in Türkiye identified erythromycin resistance in a few strains, but no resistance to penicillin was detected.

CONCLUSIONS

This study revealed that emm types 1, 12 and 89 as S. pyogenes strain genotypes were responsible for epidemic infections in Türkiye. PFGE genotyping and emm typing were found to provide better phylogenetic classification in the investigation of S. pyogenes epidemiology.

The burden of group A Streptococcus (GAS) infections: The challenge continues in the twenty-first century

Streptococcus pyogenes is a Gram-positive bacterium, also known as Group A Streptococcus (GAS), that has become a significant threat to the healthcare system, infecting more than 18 million people and resulting in more than 500,000 deaths annually worldwide. GAS infection rates decreased gradually during the 20th century in Western countries, largely due to improved living conditions and access to antibiotics. However, post-COVID-19, the situation has led to a steep increase in GAS infection rates in Europe, the United States, Australia, and New Zealand, which triggers a global concern. GAS infections are normally moderate, with symptoms of fever, pharyngitis, and pyoderma; nevertheless, if left untreated or with continued exposure to GAS or with recurring infections it can result in fatal outcomes. GAS produces a variety of virulence factors and exotoxins that can lead to deadly infections such as necrotizing fasciitis, impetigo, cellulitis, pneumonia, empyema, streptococcal toxic shock syndrome, bacteremia, and puerperal sepsis. In addition, post-immune mediated disorders such as post-streptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease contribute to extremely high death rates in developing nations. Despite substantial research on GAS infections, it is still unclear what molecular pathways are responsible for their emergence and how to best manage them. This review thus provides insights into the most recent research on the pathogenesis, virulence, resistance, and host interaction mechanisms of GAS, as well as novel management options to assist scientific communities in combating GAS infections.

Molecular Point-of-Care Testing in the Emergency Department for Group A Streptococcus Pharyngitis : A Randomized Trial

OBJECTIVES

To compare clinical and health systems outcomes of rapid molecular testing versus throat culture recovery for the management of group A Streptococcus (GAS) pharyngitis in a pediatric emergency department (PED).

METHODS

We conducted a single-center randomized trial of children (3-17 years) presenting to a PED with suspected GAS pharyngitis. A single dual-headed throat swab was collected, and participants were randomized to 1 of 2 parallel treatment groups with 1:1 allocation: point-of-care (POC) nucleic acid amplification testing or standard throat culture. The primary outcomes were time to throat pain +/- fever resolution. Secondary outcomes included absenteeism, length of stay, return visits to care, and antibiotic prescriptions and utilization.

RESULTS

A total of 227 children were randomly assigned to culture (n = 115) or POC (n = 112) testing. Antibiotics were initiated earlier in the POC group by approximately 1 day (95% confidence interval, -0.40 to -1.58). No associated difference in time to throat pain or fever resolution was observed between groups. There was a decrease in the proportion of prescribed antibiotics in the POC group (0.35) compared with the culture group (0.79; P < 0.001). Otherwise, no significant differences in secondary outcomes were observed.

CONCLUSIONS

Establishing a POC nucleic acid amplification testing program for GAS in a PED facilitates earlier treatment and fewer antibiotic prescriptions. Although this did not translate to improved clinical and health systems outcomes in our study, it may serve as an important tool amid evolving pediatric febrile illnesses and growing antimicrobial resistance patterns.

A survey of antibiotic resistance patterns among Group A Streptococcus isolated from invasive and non-invasive infections in Cape Town, South Africa

Background

There is concern regarding the increasing resistance of Group A streptococcus (GAS) to routinely used antibiotics. GAS is a common cause of bacterial pharyngitis and more severe invasive infections such as septicaemia. Furthermore, GAS pharyngitis is the antecedent for serious conditions such as rheumatic fever and rheumatic heart disease. The study aimed to determine the antimicrobial susceptibility patterns of GAS cultured from patients with invasive and non-invasive infections from Cape Town, as part of the AFROStrep Registry.

Methods

Samples were provided by the AFROStrep Registry, a continental endeavour aiming to document Streptococcus pyogenes infection in Africa and create the first biorepository of its kind. Ninety-five GAS isolates (invasive, n = 40; non-invasive, n = 55) were evaluated for resistance to a panel of 20 antibiotics using the Sensititre® STP6F system with MICs interpreted by CLSI break points.

Results

Amongst all isolates, highest levels of resistance were observed with respect to tetracycline (8.33 %), followed by azithromycin (1.04 %) and erythromycin (1.04 %). No resistance to the remaining antibiotics was detected amongst all isolates. No differences with regard to MIC values were observed between isolates from invasive and non-invasive infections (p-value >0.05 for all antibiotics).

Conclusion

GAS remains susceptible to routine-antimicrobial agents used in our low-resourced setting. Eight percent of the GAS isolates were resistant to tetracycline, and we did not observe macrolide resistance as reported in high income countries. This is the first study to report on the antimicrobial patterns of GAS in South Africa. These results address a critical gap in the available data on GAS in Africa and specifically South Africa and, thus, aid in avoiding therapeutic failures.

Characterization of group A streptococci causing invasive diseases in Sri Lanka

Group A β 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.

The overlooked bacterial pandemic

The COVID-19 pandemic had a significant economic and health impact worldwide. It also reinforced the misperception that only viruses can pose a threat to human existence, overlooking that bacteria (e.g., plague and cholera) have severely haunted and shaped the course of human civilization. While the world is preparing for the next viral pandemic, it is again overlooking a silent one: antimicrobial resistance (AMR). This review proposes to show the impact of bacterial infections on civilization to remind the pandemic potential. The work will also discuss a few examples of how bacteria can mutate risking global spread and devastating outcomes, the effect on the global burden, and the prophylactic and therapeutic measures. Indeed, AMR is dramatically increasing and if the trend is not reversed, it has the potential to quickly turn into the most important health problem worldwide.

Evolving microbial patterns of acute mastoiditis in pediatric patients undergoing mastoidectomy

OBJECTIVE

To investigate the microbial patterns and clinical outcomes of pediatric patients undergoing mastoidectomy for acute coalescent mastoiditis and to identify factors associated with poor outcomes and/or prolonged treatment.

STUDY DESIGN

Monocentric retrospective cohort study.

SETTING

Tertiary referral pediatric hospital in Indiana.

METHODS

By cross-referencing database data from the Pediatric Health Information System (PHIS) querying for all inpatient stays (patients younger than eighteen) with a diagnostic code of mastoiditis between January 1st, 2010 and August 31, 2019, and the electronic health record (Cerner) for Riley Hospital for Children, 46 patients with mastoidectomy were included. A two-tailed T-test was used to evaluate continuous parametric data. Statistical significance was determined as P < 0.05. For continuous variables, data was analyzed using continuous logistic regression. A criteria of p > 0.1 was used for inclusion in the multivariate regression.

RESULTS

Inclusion criteria was met by 46 patients. From 2010 to 2019, S. pyogenes and S. pneumoniae were the most common bacteria, each isolated in 11 of 42 bacterial isolates (26.2%). There was no growth in 35.4% (17/48) of intra-operative wound cultures. On univariate analysis, patients with negative cultures had longer length of hospital stay (LOS) (7.7 days [6.5] vs. 4.3 [2.8]; p = 0.018) as well as higher rates of PICC (peripherally inserted central catheter) placement (53.3% vs. 19.4%; p = 0.021). There was a statistically significant difference in terms of gender (p = 0.021), with 15 males and 16 females in the positive culture cohort and 13 males and 2 females in the negative culture cohort. On multivariate analysis, which included gender, PICC placement, both intracranial and extracranial complications, duration of antibiotics, and LOS, female gender was the only significant predictor of positive culture status (p = 0.039).

CONCLUSION

S. pyogenes and S. pneumoniae were the predominant etiologic agents in acute coalescent mastoiditis between 2010 and 2019, and negative wound cultures were associated with worse clinical outcomes.

Not so uncommon, yet neglected 'Severe Streptococcus pyogenes infections at a tertiary care center in south India

Streptococcus pyogenes (SP) causes uncomplicated infections of throat & skin to severe life-threatening invasive diseases and poststreptococcal sequelae. Despite being common, it hasn't been studied much in recent times. Data of 93 adult patients >18 years, culture proven (SP) infections from 2016 to 2019 was studied in south India. Irrespective of comorbidities, SSTI were most common followed by surgical site infections& bacteremia. Isolates were susceptible to penicillin, cephalosporins but 23% were resistant to clindamycin. Timely surgical interventions and appropriate antibiotics reduced morbidity& limb salvage by 9 times. Larger studies, worldwide, to see the current trend of SP need to be conducted.

An Overview of Macrolide Resistance in Streptococci: Prevalence, Mobile Elements and Dynamics

Streptococcal infections are usually treated with beta-lactam antibiotics, but, in case of allergic patients or reduced antibiotic susceptibility, macrolides and fluoroquinolones are the main alternatives. This work focuses on studying macrolide resistance rates, genetic associated determinants and antibiotic consumption data in Spain, Europe and also on a global scale. Macrolide resistance (MR) determinants, such as ribosomal methylases (erm(B), erm(TR), erm(T)) or active antibiotic efflux pumps and ribosomal protectors (mef(A/E)-mrs(D)), are differently distributed worldwide and associated with different clonal lineages and mobile genetic elements. MR rates vary together depending on clonal dynamics and on antibiotic consumption applying selective pressure. Among Streptococcus, higher MR rates are found in the viridans group, Streptococcus pneumoniae and Streptococcus agalactiae, and lower MR rates are described in Streptococcus pyogenes. When considering different geographic areas, higher resistance rates are usually found in East-Asian countries and milder or lower in the US and Europe. Unfortunately, the availability of data varies also between countries; it is scarce in low- and middle- income countries from Africa and South America. Thus, surveillance studies of macrolide resistance rates and the resistance determinants involved should be promoted to complete global knowledge among macrolide resistance dynamics.

Loss of rpoE Encoding the δ-Factor of RNA Polymerase Impacts Pathophysiology of the Streptococcus pyogenes M1T1 Strain 5448

Streptococcus pyogenes, also known as the Group A Streptococcus (GAS), is a Gram-positive bacterial pathogen of major clinical significance. Despite remaining relatively susceptible to conventional antimicrobial therapeutics, GAS still causes millions of infections and hundreds of thousands of deaths each year worldwide. Thus, a need for prophylactic and therapeutic interventions for GAS is in great demand. In this study, we investigated the importance of the gene encoding the delta (δ) subunit of the GAS RNA polymerase, rpoE, for its impact on virulence during skin and soft-tissue infection. A defined 5448 mutant with an insertionally-inactivated rpoE gene was defective for survival in whole human blood and was attenuated for both disseminated lethality and lesion size upon mono-culture infection in mouse soft tissue. Furthermore, the mutant had reduced competitive fitness when co-infected with wild type (WT) 5448 in the mouse model. We were unable to attribute this attenuation to any observable growth defect, although colony size and the ability to grow at higher temperatures were both affected when grown with nutrient-rich THY media. RNA-seq of GAS grown in THY to late log phase found that mutation of rpoE significantly impacted (>2-fold) the expression of 429 total genes (205 upregulated, 224 downregulated), including multiple virulence and “housekeeping” genes. The arc operon encoding the arginine deiminase (ADI) pathway was the most upregulated in the rpoE mutant and this could be confirmed phenotypically. Taken together, these findings demonstrate that the delta (δ) subunit of RNA polymerase is vital in GAS gene expression and virulence.

When to Use Antibiotics in COVID-19: A Proposal Based on Questions

The COVID-19 pandemic has affected millions of people, including hundreds of deaths. The search for adequate treatments and interventions that influence poor prognostic factors and reduce mortality has led to excessive use of antibiotics based on the possible existence of bacterial co-infection. However, there is no evidence to justify the systematic use of antimicrobials in COVID-19. The recommendations seek to provide knowledge regarding treatment; standardizing a management algorithm requires validation in clinical trials and studies of greater methodological rigor.

AR-12 Has a Bactericidal Activity and a Synergistic Effect with Gentamicin against Group A Streptococcus

Streptococcus pyogenes (group A Streptococcus (GAS) is an important human pathogen that can cause severe invasive infection, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The mortality rate of streptococcal toxic shock syndrome ranges from 20% to 50% in spite of antibiotics administration. AR-12, a pyrazole derivative, has been reported to inhibit the infection of viruses, intracellular bacteria, and fungi. In this report, we evaluated the bactericidal activities and mechanisms of AR-12 on GAS infection. Our in vitro results showed that AR-12 dose-dependently reduced the GAS growth, and 2.5 μg/mL of AR-12 significantly killed GAS within 2 h. AR-12 caused a remarkable reduction in nucleic acid and protein content of GAS. The expression of heat shock protein DnaK and streptococcal exotoxins was also inhibited by AR-12. Surveys of the GAS architecture by scanning electron microscopy revealed that AR-12-treated GAS displayed incomplete septa and micro-spherical structures protruding out of cell walls. Moreover, the combination of AR-12 and gentamicin had a synergistic antibacterial activity against GAS replication for both in vitro and in vivo infection. Taken together, these novel findings obtained in this study may provide a new therapeutic strategy for invasive GAS infection.

The treatment of streptococcal tonsillitis/pharyngitis in young children

Pharyngitis is common in children, accounting for nearly 12 million visits annually in the United States. Streptococcus pyogenes or group A streptococcus (GAS) is the most common bacterial cause of pharyngitis for which antibiotics are indicated. Antibiotic treatment of streptococcal pharyngitis virtually eliminates the presence of bacteria from the pharynx and thus removes the risk of subsequent rheumatic fever. GAS is spread from person to person via respiratory droplets with a short incubation period of 2∼5 days. GAS pharyngitis peaks in the late winter and early spring months when children are predominately indoors for school and sports. Colonization is also higher in winter months, and while up to 20% of school age children are colonized with GAS in their throat during this time, colonization has not been shown to contribute to the spread of disease. In low- and middle-income countries and other situations in which crowding is common (e.g., schools), outbreaks of pharyngitis are common. GAS pharyngitis can occur at all ages and it is most common in school-aged children with a peak at 7∼8 years of age. Pharyngitis caused by GAS is rare in children <3 years of age and becomes much less common in late adolescence through adulthood.

Antibiotics in treatment of peritonsillar infection: clindamycin versus penicillin

OBJECTIVE

This study aimed to compare antibiotic treatment with clindamycin versus penicillin V or G in terms of time to recovery and recurrence in patients with peritonsillar infection, including both peritonsillar cellulitis and peritonsillar abscess.

METHOD

This retrospective cohort study examined the records of 296 patients diagnosed with peritonsillar infection. Based on the ENT doctor's choice of antibiotics, patients were divided into clindamycin and penicillin groups.

RESULTS

Mean number of days in follow up was 3.5 days in the clindamycin group and 3.4 days in the penicillin group. The recurrence rate within 2 months was 7 per cent in the clindamycin group and 4 per cent in the penicillin group.

CONCLUSION

This study found no significant differences in either recovery or recurrence between the groups. This supports the use of penicillin as a first-line treatment, considering the greater frequency of adverse effects of clindamycin shown in previous studies, as well as its profound collateral damage on the intestinal microbiota, resulting in antibiotic resistance.

Antibiotic Resistance - A Cause for Reemergence of Infections

This article can rightly be called 'the rise of the microbial phoenix'; for, all the microbial infections whose doomsday was predicted with the discovery of antibiotics, have thumbed their noses at mankind and reemerged phoenix like. The hubris generated by Sir Alexander Fleming's discovery of Penicillin in 1928, exemplified best by the comment by William H Stewart, the US Surgeon General in 1967, "It is time to close the books on infectious diseases" has been replaced by the realisation that the threat of antibiotic resistance is, in the words of the Chief Medical Officer of England, Dame Sally Davies, "just as important and deadly as climate change and international terrorism". Antimicrobial resistance threatens to negate all the major medical advances of the last century because antimicrobial use is linked to many other fields like organ transplantation and cancer chemotherapy. Antibiotic resistance genes have been there since ancient times in response to naturally occurring antibiotics. Modern medicine has only driven further evolution of antimicrobial resistance by use, misuse, overuse and abuse of antibiotics. Resistant bacteria proliferate by natural selection when their drug sensitive comrades are removed by antibiotics. In this article the authors discuss the various causes of antimicrobial resistance and dwell in some detail on antibiotic resistance in gram-positive and gram-negative organisms. Finally they stress on the important role clinicians have in limiting the development and spread of antimicrobial resistance.

Molecular epidemiology and antimicrobial resistance of group a streptococcus recovered from patients in Beijing, China

BACKGROUND

Group A streptococcus (GAS) is an important human pathogen responsible for a broad range of infections. Epidemiological surveillance has been crucial to detect changes in the geographical and temporal variation of the disease pattern. The objective of this study was to investigate the molecular epidemiological characteristics and antimicrobial resistance of GAS isolates from patients in Children's Hospital in Beijing.

METHODS

From 2016 to 2017, pharyngeal swab samples were collected from the outpatients in Children's Hospital, Capital Institute of Pediatrics, who were diagnosed with scarlet fever. Antimicrobial susceptibility test was performed according to the distribution of conventional antibiotics and Clinical and Laboratory Standards Institute (CLSI) recommendations. The distribution of the macrolide-resistance genes (ermB, ermA, mefA), emm (M protein-coding gene) typing, and superantigens (SAg) gene profiling were examined by polymerase chain reaction (PCR).

RESULTS

A total of 297 GAS isolates were collected. The susceptibility of the isolates to penicillin, ceftriaxone, and levofloxacin was 100%. The resistance rate to erythromycin and clindamycin was 98.3 and 96.6%, respectively. The dominant emm types were emm12 (65.32%), emm1 (27.61%), emm75 (2.69%), and emm89 (1.35%). Of the 297 isolates, 290 (97.64%) carried the ermB gene, and 5 (1.68%) carried the mefA gene, while none carried the ermA gene. The most common superantigen genes identified from GAS isolates were smeZ (96.97%), speC (92.59%), speG (91.58%), ssa (85.52%), speI (54.55%), speH (52.19%), and speA (34.34%). Isolates with the genotype emm1 possessed speA, speC, speG, speJ, speM, ssa, and smeZ, while emm12 possessed speC, speG, speH, speI, speM, ssa, and smeZ superantigens.

CONCLUSIONS

The prevalent strain of GAS isolates in Beijing has a high resistance rate to macrolides; however, penicillin can still be the preferred antibiotic for treatment. Erythromycin resistance was predominantly mediated by ermB. The common emm types were emm12 and emm1. There was a correlation between emm and the superantigen gene. Thus, long-term monitoring and investigation of the emm types and superantigen genes of GAS prevalence are imperative.

Molecular emm typing of Bulgarian macrolide-resistant Streptococcus pyogenes isolates

Group A streptococcus (GAS) is a human pathogen causing a broad range of infections, linked with global morbidity and mortality. Macrolide resistance rates vary significantly in different parts of the world. Driving factors of the emergence and spread of resistant clones are not clearly understood. We investigated 102 macrolide-resistant GAS strains collected during the period 2014-2018 from various clinical specimens from Bulgarian patients. Strains were characterized by the presence of mefA/mefE, ermA, and ermB using polymerase chain reaction and sequencing for mefA/mefE. Resistant strains were studied by emm sequence typing and emm-cluster system. Most prevalent emm types among the macrolide-resistant GAS strains were emm28 (22.55%), emm12 (17.65%), and emm4 (16.66%). Almost all (87.25%) of the macrolide-resistant isolates harboring ermB were emm28. The isolates that carried ermA were predominantly emm12 (38.24%) and emm77 (38.24%), with fewer emm89 (23.53%). The isolates harbored predominantly mefE (49 isolates) and only 9 strains carried mefA. The most prevalent emm clusters among the GAS isolates were E4 (40.20%), A-C4 (17.65%), and E1 (16.66%). The study's results suggest that dissemination of specific clones in GAS population may also be the reason for the increasing macrolide-resistance rate in our country.