Studies of the continuing susceptibility of group A streptococcal strains to penicillin during eight decades

Antibiotic consumption for sore throat and the potential effect of a vaccine against group A Streptococcus: a systematic review and modelling study

BACKGROUND

Antibiotic consumption can lead to antimicrobial resistance and microbiome imbalance. We sought to estimate global antibiotic consumption for sore throat, and the potential reduction in consumption due to effective vaccination against group A Streptococcus (Strep A).

METHODS

We reviewed and analysed articles published between January 2000 and February 2022, identified though Clarivate Analytics' Web of Science search platform, with reference to antibiotic prescribing or consumption, sore throat, pharyngitis, or tonsillitis. We then used those analyses, combined with assumptions for the effectiveness, duration of protection, and coverage of a vaccine, to calculate the estimated reduction in antibiotic prescribing due to the introduction of Strep A vaccines.

FINDINGS

We identified 101 studies covering 38 countries. The mean prescribing rate for sore throat was approximately 5 courses per 100 population per year, accounting for approximately 5% of all antibiotic consumption. Based on 2020 population estimates for countries with empiric prescribing rates, antibiotic consumption for sore throat was estimated to exceed 37 million courses annually, of which half could be attributable to treatment for Strep A. A vaccine that reduces rates of Strep A infection by 80%, with 80% coverage and 10 year's duration of protection, could avert 2.8 million courses of antibiotics prescribed for sore throat treatment among 5-14 year-olds in countries with observed prescribing rates, increasing to an estimated 7.5 million averted if an effective vaccination program also reduced precautionary prescribing.

INTERPRETATION

A vaccine that prevents Strep A throat infections in children may reduce antibiotic prescribing for sore throat by 32-87% depending on changes to prescribing and consumption behaviours.

FUNDING

The Wellcome Trust, grant agreement number 215490/Z/19/Z.

Study protocol for controlled human infection for penicillin G against Streptococcus pyogenes: a double-blinded, placebo-controlled, randomised trial to determine the minimum concentration required to prevent experimental pharyngitis (the CHIPS trial)

INTRODUCTION

Regular intramuscular benzathine penicillin G injections have been the cornerstone of rheumatic heart disease (RHD) secondary prophylaxis since the 1950s. As the pharmacological correlate of protection remains unknown, it is difficult to recommend changes to this established regimen. Determining the minimum effective penicillin exposure required to prevent Streptococcus pyogenes infection will accelerate development of new long-acting penicillins for RHD prevention as well as inform opportunities to improve existing regimens. The CHIPS trial will address this knowledge gap by directly testing protection afforded by different steady state plasma concentrations of penicillin in an established model of experimental human S. pyogenes pharyngitis.

METHODS AND ANALYSIS

This is a double-blinded, placebo-controlled, randomised experimental human infection study. Sixty healthy adult volunteers aged 18-40 years will be recruited and randomised 1:1:1:1:1 to continuous intravenous penicillin infusions targeting five different steady state plasma concentrations of 0 (placebo), 3, 6, 12 and 20 ng/mL via a midline catheter. Each participant's penicillin pharmacokinetic parameters will be established prior to the challenge, to ensure accurate dosing for the continuous infusion. Following the challenge with a well-characterised strain of S. pyogenes, participants will be observed for up to 6 days for the development of pharyngitis and treated with antibiotics prior to discharge. The primary objective is to determine the minimum effective steady-state plasma penicillin concentration required to prevent experimental pharyngitis. Secondary objectives will explore systemic and mucosal immunoinflammatory responses during pharyngitis, bacterial colonisation dynamics, environmental contamination and qualitative evaluation of the participant experience.

ETHICS AND DISSEMINATION

Ethical approval has been obtained (Bellberry Human Research Ethics Committee). Findings will be reported in peer-reviewed publications and presented at national/international stakeholder forums.

TRIAL REGISTRATION NUMBER

ACTRN12621000751875.

A Chimeric Penicillin Binding Protein 2X Significantly Decreases in Vitro Beta-Lactam Susceptibility and Increases in Vivo Fitness of Streptococcus pyogenes

All tested strains of Streptococcus pyogenes (group A streptococcus, GAS) remain susceptible to penicillin. However, GAS strains with amino acid substitutions in penicillin-binding proteins that confer decreased susceptibility to beta-lactam antibiotics have been identified recently. This discovery raises concerns about emergence of beta-lactam antibiotic resistance in GAS. Whole genome sequencing recently identified GAS strains with a chimeric penicillin-binding protein 2X (PBP2X) containing a recombinant segment from Streptococcus dysgalactiae subspecies equisimilis (SDSE). To directly test the hypothesis that the chimeric SDSE-like PBP2X alters beta-lactam susceptibility in vitro and fitness in vivo, an isogenic mutant strain was generated and virulence assessed in a mouse model of necrotizing myositis. Compared with naturally occurring and isogenic strains with a wild-type GAS-like PBP2X, strains with the chimeric SDSE-like PBP2X had reduced susceptibility in vitro to nine beta-lactam antibiotics. In a mouse model of necrotizing myositis, the strains had identical fitness in the absence of benzylpenicillin treatment. However, mice treated intermittently with a subtherapeutic dose of benzylpenicillin had significantly more colony-forming units recovered from limbs infected with strains with the chimeric SDSE-like PBP2X. These results show that mutations such as the PBP2X chimera may result in significantly decreased beta-lactam susceptibility and increased fitness and virulence. Expanded diagnostic laboratory surveillance, genome sequencing, and molecular pathogenesis study of potentially emergent beta-lactam antibiotic resistance among GAS are needed.

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.

The Chemical Relationship Among Beta-Lactam Antibiotics and Potential Impacts on Reactivity and Decomposition

Beta-lactam antibiotics remain one of the most commonly prescribed drug classes, but they are limited by their propensity to cause hypersensitivity reactions (e.g., from allergy to anaphylaxis) as well as by the emergence of bacteria with a myriad of resistance mechanisms such as β-lactamases. While development efforts continue to focus on overcoming resistance, there are ongoing concerns regarding cross-contamination of β-lactams during manufacturing and compounding of these drugs. Additionally, there is a need to reduce levels of drugs such as β-lactam antibiotics in waste-water to mitigate the risk of environmental exposure. To help address future development of effective remediation chemistries and processes, it is desired to better understand the structural relationship among the most common β-lactams. This study includes the creation of a class-wide structural ordering of the entire β-lactam series, including both United States Food and Drug Association (US-FDA)-approved drugs and experimental therapies. The result is a structural relational map: the "Lactamome," which positions each substance according to architecture and chemical end-group. We utilized a novel method to compare the structural relationships of β-lactam antibiotics among the radial cladogram and describe the positioning with respect to efficacy, resistance to hydrolysis, reported hypersensitivity, and Woodward height. The resulting classification scheme may help with the development of broad-spectrum treatments that reduce the risk of occupational exposure and negative environmental impacts, assist practitioners with avoiding adverse patient reactions, and help direct future drug research.

Antibiotic Treatment, Mechanisms for Failure, and Adjunctive Therapies for Infections by Group A Streptococcus

Group A Streptococcus (GAS; Streptococcus pyogenes) is a nearly ubiquitous human pathogen responsible for a significant global disease burden. No vaccine exists, so antibiotics are essential for effective treatment. Despite a lower incidence of antimicrobial resistance than many pathogens, GAS is still a top 10 cause of death due to infections worldwide. The morbidity and mortality are primarily a consequence of the immune sequelae and invasive infections that are difficult to treat with antibiotics. GAS has remained susceptible to penicillin and other β-lactams, despite their widespread use for 80 years. However, the failure of treatment for invasive infections with penicillin has been consistently reported since the introduction of antibiotics, and strains with reduced susceptibility to β-lactams have emerged. Furthermore, isolates responsible for outbreaks of severe infections are increasingly resistant to other antibiotics of choice, such as clindamycin and macrolides. This review focuses on the challenges in the treatment of GAS infection, the mechanisms that contribute to antibiotic failure, and adjunctive therapeutics. Further understanding of these processes will be necessary for improving the treatment of high-risk GAS infections and surveillance for non-susceptible or resistant isolates. These insights will also help guide treatments against other leading pathogens for which conventional antibiotic strategies are increasingly failing.

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.

Toxic Shock Syndrome after Surgery: Case Presentation and Systematic Review of the Literature

Toxic shock syndrome (TSS) is an underrecognized but highly fatal cause of septic shock in postoperative patients. Although it may present with no overt source of infection, its course is devastating and rapidly progressive. Surgeon awareness is needed to recognize and treat this condition appropriately. In this paper, we aim to describe a case of postoperative TSS, present a systematic review of the literature, and provide an overview of the disease for the surgeon.

METHODS

A systematic review of the literature between 1978 and 2018 was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the keywords "toxic shock syndrome" and "surgery." Variables of interest were collected in each report.

RESULTS

A total of 298 reports were screened, and 67 reports describing 96 individual patients met inclusion criteria. Six reports described a streptococcal cause, although the vast majority attributed TSS to Staphylococcus aureus (SA). The mortality in our review was 9.4%, although 24% of patients suffered some manner of permanent complication. TSS presented at a median of 4 days postoperatively, with most cases occurring within 10 days.

CONCLUSIONS

Surgeons must maintain a high index of suspicion for postoperative TSS. Our review demonstrates that TSS should not be excluded despite young patient age, patient health, or relative simplicity of a procedure. Symptoms such as fever, rash, pain out of proportion to examination, and diarrhea or emesis should raise concern for TSS and prompt exploration and cultures even of benign-appearing postoperative wounds.

Group A Streptococcus infections in children: from virulence to clinical management

PURPOSE OF REVIEW

Recent findings have open new perspectives on group A Streptococcus (GAS) virulence understanding with special focus on the carrier stage and new hopes for an efficient vaccine against this important pathogen.

RECENT FINDINGS

Understanding of carriage state, transmission and role of virulence factors in invasive infections have been recently active research fields questioning the link between carriage and infections and highlighting the potential to prevent invasive diseases. New roles for already well known virulence factors, such as Streptolysin O, M protein or NAD(+)-glycohydrolase have been discovered. Immunological studies have also shown diversity in both clinical and immunological responses toward various GAS antigens raising questions, and hopes, for the development of an efficient global vaccine candidate.

SUMMARY

A greater understanding of GAS virulence strategies, and their associated clinical manifestations, may be obtained by shifting our research scope toward virulence determinant interactions and cooperation rather than focusing on individual virulence factor or specific strain characterization only.

Streptococcal toxic shock syndrome in the intensive care unit

The streptococcal toxic shock syndrome is a severe complication associated with invasive infections by group A streptococci. In spite of medical progresses in the care of patients with septic shock during the last decades, this condition has remained associated with a high mortality. Early recognition and multidisciplinary management are key to the care of patients with streptococcal toxic shock syndrome, with intensive and appropriate intensive support of failing organs, rapid diagnosis of infectious source(s), and surgical management. The epidemiology and risk factors for streptococcal toxic shock syndrome remain to be better studied, including the possible causal role of exposure to nonsteroidal anti-inflammatory drugs. In this review article, the authors review the current knowledge of streptococcal toxic shock syndrome and discuss the pathophysiology as well as its supportive and specific treatment.

Treatment Challenges of Group A Beta-hemolytic Streptococcal Pharyngo-Tonsillitis

Introduction  Despite its in vitro efficacy, penicillin often fails to eradicate Group A β-hemolytic streptococci (GABHS) from patients with acute and relapsing pharyngo-tonsillitis (PT). Objective  This review of the literature details the causes of penicillin failure to eradicate GABHS PT and the therapeutic modalities to reduce and overcome antimicrobial failure. Data Synthesis  The causes of penicillin failure in eradicating GABHS PT include the presence of β lactamase producing bacteria (BLPB) that "protect" GABHS from any penicillin; the absence of bacteria that interfere with the growth of GABHS; co-aggregation between GABHS and Moraxella catarrhalis; and the poor penetration of penicillin into the tonsillar tissues and the tonsillo-pharyngeal cells, which allows intracellular GABHS and Staphylococcus aureus to survive. The inadequate intracellular penetration of penicillin can allow intracellular GABHS and S. aureus to persist. In the treatment of acute tonsillitis, the use of cephalosporin can overcome these interactions by eradicating aerobic BLPB (including M. catarrhalis), while preserving the potentially interfering organisms and eliminating GABHS. Conclusion  In treatment of recurrent and chronic PT, the administration of clindamycin, or amoxicillin-clavulanic acid, can eradicate both aerobic and anaerobic BLPB, as well as GABHS. The superior intracellular penetration of cephalosporin and clindamycin also enhances their efficacy against intracellular GABHS and S. aureus.

Systematic review of factors contributing to penicillin treatment failure in Streptococcus pyogenes pharyngitis

Objective

Review the evidence for various explanations for microbiologic treatment failure following use of penicillin in group A streptococcal (GAS) tonsillopharyngitis.

DATA SOURCE

Systematic review of the literature based on Medline and EMBASE searches, and review of reference lists of included studies.

RESULTS

The explanations for penicillin treatment failure in GAS tonsillopharyngitis include 1) carrier state, 2) lack of compliance, 3) recurrent exposure, 4) in vivo copathogenicity of β-lactamase–producing normal pharyngeal flora, 5) in vivo bacterial coaggregation, 6) poor antibiotic penetration to tonsillopharyngeal tissue, 7) in vivo eradication of normal protective flora, 8) early initiation of antibiotic therapy resulting in suppression of an adequate host immune response, 9) intracellular localization of GAS, 10) GAS tolerance to penicillin, 11) contaminated toothbrushes or orthodontic appliances, and 12) transmission from the family pet. There is very little type I or II evidence to support any of the above-cited explanations for treatment failure in GAS tonsillopharyngitis; available studies are mostly observational (in patients) or laboratory-based without clinical confirmation.

CONCLUSION

Multiple explanations have been offered by investigators to explain penicillin treatment failures in GAS tonsillopharyngitis, but the evidence base to support the proposed explanations is generally weak by current standards. Further research is needed to better understand the mechanism(s) of penicillin treatment failure in GAS tonsillopharyngitis.

Disease manifestations and pathogenic mechanisms of Group A Streptococcus

Streptococcus pyogenes, also known as group A Streptococcus (GAS), causes mild human infections such as pharyngitis and impetigo and serious infections such as necrotizing fasciitis and streptococcal toxic shock syndrome. Furthermore, repeated GAS infections may trigger autoimmune diseases, including acute poststreptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. Combined, these diseases account for over half a million deaths per year globally. Genomic and molecular analyses have now characterized a large number of GAS virulence determinants, many of which exhibit overlap and redundancy in the processes of adhesion and colonization, innate immune resistance, and the capacity to facilitate tissue barrier degradation and spread within the human host. This improved understanding of the contribution of individual virulence determinants to the disease process has led to the formulation of models of GAS disease progression, which may lead to better treatment and intervention strategies. While GAS remains sensitive to all penicillins and cephalosporins, rising resistance to other antibiotics used in disease treatment is an increasing worldwide concern. Several GAS vaccine formulations that elicit protective immunity in animal models have shown promise in nonhuman primate and early-stage human trials. The development of a safe and efficacious commercial human vaccine for the prophylaxis of GAS disease remains a high priority.

Disease manifestations and pathogenic mechanisms of Group A Streptococcus

Streptococcus pyogenes, also known as group A Streptococcus (GAS), causes mild human infections such as pharyngitis and impetigo and serious infections such as necrotizing fasciitis and streptococcal toxic shock syndrome. Furthermore, repeated GAS infections may trigger autoimmune diseases, including acute poststreptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. Combined, these diseases account for over half a million deaths per year globally. Genomic and molecular analyses have now characterized a large number of GAS virulence determinants, many of which exhibit overlap and redundancy in the processes of adhesion and colonization, innate immune resistance, and the capacity to facilitate tissue barrier degradation and spread within the human host. This improved understanding of the contribution of individual virulence determinants to the disease process has led to the formulation of models of GAS disease progression, which may lead to better treatment and intervention strategies. While GAS remains sensitive to all penicillins and cephalosporins, rising resistance to other antibiotics used in disease treatment is an increasing worldwide concern. Several GAS vaccine formulations that elicit protective immunity in animal models have shown promise in nonhuman primate and early-stage human trials. The development of a safe and efficacious commercial human vaccine for the prophylaxis of GAS disease remains a high priority.

Inhibition of Growth and Gene Expression by PNA-peptide Conjugates in Streptococcus pyogenes

While Streptococcus pyogenes is consistently susceptible toward penicillin, therapeutic failure of penicillin treatment has been reported repeatedly and a considerable number of patients exhibit allergic reactions to this substance. At the same time, streptococcal resistance to alternative antibiotics, e.g., macrolides, has increased. Taken together, these facts demand the development of novel therapeutic strategies. In this study, S. pyogenes growth was inhibited by application of peptide-conjugated antisense-peptide nucleic acids (PNAs) specific for the essential gyrase A gene (gyrA). Thereby, HIV-1 Tat peptide-coupled PNAs were more efficient inhibitors of streptococcal growth as compared with (KFF)3K-coupled PNAs. Peptide-anti-gyrA PNAs decreased the abundance of gyrA transcripts in S. pyogenes. Growth inhibition by antisense interference was enhanced by combination of peptide-coupled PNAs with protein-level inhibitors. Antimicrobial synergy could be detected with levofloxacin and novobiocin, targeting the gyrase enzyme, and with spectinomycin, impeding ribosomal function. The prospective application of carrier peptide-coupled antisense PNAs in S. pyogenes covers the use as an antimicrobial agent and the employment as a knock-down strategy for the investigation of virulence factor function.

Benzathine Penicillin G for the Management of RHD: Concerns About Quality and Access, and Opportunities for Intervention and Improvement

Benzathine penicillin G is an important antibiotic for the treatment and prevention of group A streptococcal infections associated with rheumatic fever and rheumatic heart disease. However, as rheumatic heart disease has receded as a public health priority in most high-income settings, attention to the supply, manufacture, and accessibility of benzathine penicillin G has declined. Concerns about the quality, efficacy, and innovation of the drug have emerged following plasma analysis and anecdotal reports from low-resource settings. This review collates core issues in supply and delivery of benzathine penicillin G as a foundation for concerted efforts to improve global quality and access. Opportunities for intervention and improvement are explored.

Antimicrobial susceptibility pattern of β-haemolytic group A, C and G streptococci isolated from North India

The objective of this study was to determine the antibiotic resistance amongst beta-haemolytic streptococci (BHS) from North India. A total of 155 BHS isolates, comprising group A streptococci (GAS) (102), group C streptococci (GCS) (25) and group G streptococci (GGS) (28), collected from patients with pharyngitis, rheumatic fever, skin disease and invasive disease were analysed for their antimicrobial susceptibility to 20 antibiotics using the Kirby-Bauer disc diffusion method. The MICs of penicillin, tetracycline, clarithromycin, azithromycin and erythromycin were also determined using the HiComb test, following the Clinical and Laboratory Standards Institute guidelines. The results showed that 37.4% of BHS isolates were susceptible to all antibiotics and 19.4% were highly resistant to tetracycline; however, only 2.6-5.2% were resistant to macrolides. The tetracycline resistance (P<0.05) of BHS was found to be statistically significant. GAS isolates from different sources of infection also showed statistically significant antibiotic resistance to azithromycin (P=0.029). Multi-drug resistance was found irrespective of streptococcal emm types. No association between GAS emm types and drug resistance was seen. MIC determination showed all isolates to be susceptible to the five antibiotics tested, except for two GAS and one GGS isolates that were resistant to clarithromycin, and one GAS skin isolate that was resistant to tetracycline. This study suggests that the variation in antibiotic resistance amongst BHS isolates from North India is independent of the isolation source and emm type distribution, hence emphasizing the need for a longitudinal surveillance in different regions of India.

Lack of hygiene routines among patients and family members at patient hotels--a possible route for transmitting puerperal fever

The use of patient hotels for ambulatory care of women with uncomplicated deliveries has become a routine in Sweden. This report describes a minor outbreak of a group A Streptococcus strain in 2 newly delivered mothers and their newborn babies at a patient hotel.

Group A streptococcal pharyngitis and immune-mediated complications: from diagnosis to management

Group A streptococcal pharyngitis remains the most important bacterial pharyngitis because of its frequency and potential complications. Group A streptococcal pharyngitis is most common in children 5-11 years of age in winter-spring, and a rapid test or culture is necessary for accurate diagnosis. We propose a management strategy for those geographic areas with very low acute rheumatic fever rates, emphasizing selective testing that avoids testing those patients with viral-like features (e.g., rhinorrhea and cough). Acute rheumatic fever is the most important immune-mediated sequela and has become rare in most areas of the USA and Western Europe, most probably due to decreased circulation of highly rheumatogenic group A streptococcal strains.

Inference of antibiotic resistance and virulence among diverse group A Streptococcus strains using emm sequencing and multilocus genotyping methods

Background

Group A Streptococcus pyogenes (GAS) exhibits a high degree of clinically relevant phenotypic diversity. Strains vary widely in terms of antibiotic resistance (AbR), clinical severity, and transmission rate. Currently, strain identification is achieved by emm typing (direct sequencing of the genomic segment coding for the antigenic portion of the M protein) or by multilocus genotyping methods. Phenotype analysis, including critical AbR typing, is generally achieved by much slower and more laborious direct culture-based methods.

Methodology/Principal Findings

We compare genotype identification (by emm typing and PCR/ESI-MS) with directly measured phenotypes (AbR and outbreak associations) for 802 clinical isolates of GAS collected from symptomatic patients over a period of 6 years at 10 military facilities in the United States. All independent strain characterization methods are highly correlated. This shows that recombination, horizontal transfer, and other forms of reassortment are rare in GAS insofar as housekeeping genes, primary virulence and antibiotic resistance determinants, and the emm gene are concerned. Therefore, genotyping methods offer an efficient way to predict emm type and the associated AbR and virulence phenotypes.

Conclusions/Significance

The data presented here, combined with much historical data, suggest that emm typing assays and faster molecular methods that infer emm type from genomic signatures could be used to efficiently infer critical phenotypic characteristics based on robust genotype: phenotype correlations. This, in turn, would enable faster and better-targeted responses during identified outbreaks of constitutively resistant or particularly virulent emm types.

Boesenbergia pandurata (Roxb.) Schltr., Eleutherine americana Merr. and Rhodomyrtus tomentosa (Aiton) Hassk. as antibiofilm producing and antiquorum sensing in Streptococcus pyogenes

Biofilm formation has been demonstrated as a potentially important mechanism contributing to antibiotic treatment failure on Streptococcus pyogenes. It could play a significant role in recurrent and chronic infections. Boesenbergia pandurata (Roxb.) Schltr., Eleutherine americana Merr. and Rhodomyrtus tomentosa (Aiton) Hassk. have been previously reported from our laboratory as effective agents against S. pyogenes. Therefore, in the present study, we observed the effect of these plants on biofilm formation. The bacterial biofilms were quantified by safranin staining and absorbance at 492 nm. The results clearly demonstrated that all subinhibitory concentrations [1/32-1/2 minimal inhibitory concentration (MIC)] of E. americana (7.81-125 microg mL(-1)) and R. tomentosa (0.24-7.81 microg mL(-1)) extracts significantly prevented biofilm formation while 1/2MIC (7.81 microg mL(-1)) of B. pandurata extract produced this effect. The issue of antiquorum sensing of this pathogenic bacterium has been further explored. A correlation between antiquorum-sensing and antibiofilm-producing activities was demonstrated. Strong inhibition on quorum sensing was displayed with the extract of R. tomentosa. Eleutherine americana extract showed partial inhibition, while B. pandurata did not show this activity. By contrast, an assay of microbial adhesion to hydrocarbon revealed no changes in the cell-surface hydrophobicity of the treated organisms. Active organisms with the ability to inhibit quorum sensing and biofilm formation are worth studying as they may provide complimentary medicine for biofilm-associated infections.

Unexpected individual clinical site variation in eradication rates of group a streptococci by penicillin in multisite clinical trials

BACKGROUND

Previously, we reported an unexpectedly large percentage of failures by penicillin to eradicate group A streptococci (GAS) from the upper respiratory tract. Because penicillin has been the recommended therapy for the treatment of GAS pharyngitis, our report prompted controversy. Data from clinical trials in which our laboratory has participated demonstrated marked variation in GAS eradication rates among clinical sites. The reasons for such variation have never been adequately examined. We performed statistical analyses of site variation in eradication rates to assess the potential effect on reported reduced penicillin efficacy.

METHODS

Penicillin GAS eradication rates were compared using data from 4 large multisite pharyngitis treatment trials (75 clinical sites; 1158 subjects). Variation in eradication rates among clinical sites was statistically evaluated [chi(2) tests and generalized estimating equation (GEE) regression models].

RESULTS

There was significant site-to-site variation in GAS eradication rates in each of the trials (range, 17-100%; P < 0.005) as well as between separate trials (mean range, 58-69%; P < 0.033). GEE modeling indicated that GAS eradication rates were significantly higher for clinical sites participating in more than one clinical trial.

CONCLUSIONS

The statistically significant site-to-site variation in penicillin eradication rates was related to factors (dependencies) at individual sites. Such factors may affect assessment of therapeutic efficacy and indicate a necessity for considering clinical site variation before reporting pooled efficacy data from multiple sites; combined data may result in misleading clinical implications. This is the first report documenting significant variation resulting from individual clinical site-related factors and offers a possible explanation for reduced penicillin eradication.

Invasive group A streptococcal disease: should close contacts routinely receive antibiotic prophylaxis?

Group A streptococci (Streptococcus pyogenes) causes a wide range of illnesses from non-invasive disease--eg, pharyngitis--to more severe invasive infections--eg, necrotising fasciitis and toxic shock-like syndrome. There remains uncertainty about the risk of secondary cases of invasive disease occurring among close contacts of an index case and how best to manage that risk. We do not consider that currently available evidence justifies the routine administration of chemoprophylaxis to close contacts. We suggest that the appropriate response should be to routinely inform all household contacts of a patient with invasive group A streptococcal disease about the clinical manifestations of invasive disease and to seek immediate medical attention if they develop such symptoms.

Antimicrobial susceptibility and macrolide resistance genes in Streptococcus pyogenes collected in Austria and Hungary

A total of 341 clinical isolates of Streptococcus pyogenes from Vienna, Austria and three Hungarian cities were tested for susceptibility to four macrolides and 12 other antibiotics. All isolates were fully susceptible to penicillin and the other beta-lactams tested. A high level of tetracycline resistance was found in Austria (26.7%) and in Hungary (30.5%). The rate of resistance to erythromycin, clarithromycin and azithromycin was 4.7% in Vienna and 3.7% in the Hungarian communities. In both countries, the MIC(90) values of erythromycin and clarithromycin were 0.12 mg/L and the MIC(90) of josamycin was 0.5mg/L. The M phenotype of resistance conferred by the mefA genes was predominant (n = 9) among the macrolide-resistant isolates (n = 14).

Increasing antibiotic resistance of streptococcus species in New York City

OBJECTIVE

Streptococcus species are common pathogens in head and neck infections and are leading causes of morbidity and mortality. Emerging penicillin-resistant streptococcal pathogens have shifted empirical antibiotic therapy in favor of valuable alternatives, including erythromycin and clindamycin. This study was undertaken to determine the magnitude of antimicrobial resistance to these antibiotics.

STUDY DESIGN

Retrospective review.

METHODS

A retrospective study of two streptococcal species isolates, Streptococcus pyogenes (163 specimens) and Streptococcus pneumoniae (164 specimens), collected between January 1, 2001 and January 1, 2002 at two academic institutions. The antibiotic susceptibility patterns were analyzed for penicillin, erythromycin, and clindamycin according to the National Committee for Clinical Laboratory Standards.

RESULTS

Fourteen percent to 34% of S. pyogenes isolates were erythromycin-resistant, and 0% to 28% were clindamycin-resistant. None of the S. pyogenes isolates were resistant to penicillin. Of the S. pneumoniae isolates, 33% to 50% were resistant to erythromycin, and 18% to 33% were resistant to clindamycin. The penicillin resistance levels for S. pneumoniae were 0% to 45%.

CONCLUSIONS

Our antimicrobial resistance levels for S. pyogenes and S. pneumoniae significantly exceeded national and worldwide levels of erythromycin and clindamycin resistance. With a diverse population of over 8 million residents and high physician supply, our model is a microcosm for the study of antimicrobial use and susceptibility patterns and of clinical failure.

Addressing the burden of group A streptococcal disease in India

Group A streptococcus-associated disease and sequelae continue to have devastating effects on public health and national economy as they mainly affect children and young adults. There is an urgent need for wider application of methods of primary prevention, in the form of optimal diagnosis and management of the simple group A streptococcal sore throat. This review article briefly summarizes the burden of streptococcal disease in India, and discusses treatment options standardized by the World Health Organization. Penicillin continues to remain the drug of choice for treating group A streptococcal pharyngitis and for prevention of acute rheumatic fever in non-allergic patients. Also discussed in this review are contemporary thoughts on streptococcal "carriers", recurrent infections, antibiotic treatment "failures" and emergence of drug resistance among group A streptococci.

¿Cuál es la importancia de la erradicación bacteriana en el tratamiento de la infección respiratoria?

During the last few years, increasing antibiotic resistance amongst the major respiratory pathogens in the community has compromised the choice of empirical therapy for some respiratory tract infections. Of special interest has been the progressive increase in the resistance rates of Streptococcus pneumoniae to macrolides and penicillin, and of S. pyogenes to macrolides. Several studies have confirmed the association between community use of certain antibiotics and the development of resistance in S. pneumoniae and S. pyogenes. Nevertheless, not all the antibiotics have the same ability to select resistance and not all microorganisms are affected in the same way. The aim of antimicrobial therapy in respiratory tract infections is bacterial eradication. Pharmacokinetic and pharmacodynamics can be used to predict bacteriological eradication with antimicrobial therapy.

Biofilm formation by group a streptococci: is there a relationship with treatment failure?

Group A streptococcus (GAS) is the primary cause of bacterial pharyngitis in children and adults. Up to one-third of patients treated for GAS pharyngitis fail to respond to antibiotic therapy. The objective of this cohort study was to evaluate GAS biofilm formation as a mechanism for antibiotic treatment failure using previously collected GAS isolates and penicillin treatment outcome data. The minimum biofilm eradication concentration (MBEC) assay device was used to determine the biofilm-forming capabilities, efficiencies, and antibiotic susceptibilities of GAS isolates. The MBECs and MICs of several antibiotics for GAS were determined. All 99 GAS isolates available for this study formed biofilms, with various efficiencies. Antibiotic MBECs were consistently higher than MICs for all of the GAS isolates. MBECs indicated penicillin insensitivity in 60% of GAS isolates, producing the first report of in vitro GAS insensitivity to penicillin. Using MBECs to predict penicillin treatment failure had better sensitivity (56%) but lower specificity (36%) than the sensitivity (0%) and specificity (100%) when MICs were used. However, the positive predictive value of the MBEC was superior to that of the MIC (56 versus 0%), while the negative predictive values (42 and 47%) were similar. More studies are needed to understand the roles of biofilms and the MBEC assay in predicting GAS treatment failure. In addition, further investigations are necessary to determine if non-biofilm-forming strains of GAS exist and the roles of in vivo monospecies and multispecies biofilms in streptococcal pharyngitis treatment failure.

Antibacterial therapy for acute group a streptococcal pharyngotonsillitis: short-course versus traditional 10-day oral regimens

The objective of this review is to examine the use of short-course antibacterial therapy of group A beta-hemolytic streptococcal (GABHS) pharyngotonsillitis, compared with traditional 10-day therapy. In preparing this paper we reviewed the medical literature of studies comparing 10 days of penicillin with shorter courses of antibacterial therapy. Short-course therapy of 6 days of amoxicillin, 4 to 5 days of cephalosporins, and 5 days of azithromycin was found to be as, or more effective than traditional 10-day penicillin therapy. The benefits of short-course therapy include superior compliance and adherence, lower incidence of adverse effects, less effect on the bacterial flora, improved patient and parent satisfaction, and lower drug costs. In conclusion, short courses of amoxicillin, cephalosporins, and macrolides provide superior or equal efficacy to a 10-day course of penicillin therapy in the treatment of GABHS pharyngotonsillitis.

What is new in pediatric cardiology

Enormous advances in the diagnosis and management of heart disease in pediatric patient have taken place during the last-four decades. In this review the authors will concentrate on the developments within the last five to ten years. It will deal with what may be called medical advances. Recent advances in molecular genetics and defining the familial patterns have led to finding that certain genetic and molecular factors are linked to congenital heart disease and arrythmia, thus providing opportunity for improved genetic counseling and future gene therapy. Medical treatment of congenital heart disease targets not only the augmentation of ventricular contractility (positive inotropy) but also addresses the neuro-humoral derangement associated with it. The ultrasound technology for the evaluation of the heart has come a long way from the early A-mode and M-mode capabilities to color Doppler, 2-dimentional and 3-dimentional capabilities.

Surveillance of resistance in bacteria causing community-acquired respiratory tract infections

Bacterial resistance to antibiotics in community-acquired respiratory tract infections is a serious problem and is increasing in prevalence world-wide at an alarming rate. Streptococcus pneumoniae, one of the main organisms implicated in respiratory tract infections, has developed multiple resistance mechanisms to combat the effects of most commonly used classes of antibiotics, particularly the beta-lactams (penicillin, aminopenicillins and cephalosporins) and macrolides. Furthermore, multidrug-resistant strains of S. pneumoniae have spread to all regions of the world, often via resistant genetic clones. A similar spread of resistance has been reported for other major respiratory tract pathogens, including Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. To develop and support resistance control strategies it is imperative to obtain accurate data on the prevalence, geographic distribution and antibiotic susceptibility of respiratory tract pathogens and how this relates to antibiotic prescribing patterns. In recent years, significant progress has been made in developing longitudinal national and international surveillance programs to monitor antibiotic resistance, such that the prevalence of resistance and underlying trends over time are now well documented for most parts of Europe, and many parts of Asia and the Americas. However, resistance surveillance data from parts of the developing world (regions of Central America, Africa, Asia and Central/Eastern Europe) remain poor. The quantity and quality of surveillance data is very heterogeneous; thus there is a clear need to standardize or validate the data collection, analysis and interpretative criteria used across studies. If disseminated effectively these data can be used to guide empiric antibiotic therapy, and to support-and monitor the impact of-interventions on antibiotic resistance.

Prevention of invasive group A streptococcal disease among household contacts of case patients and among postpartum and postsurgical patients: recommendations from the Centers for Disease Control and Prevention

The Centers for Disease Control and Prevention hosted a workshop to formulate recommendations for the control of invasive group A streptococcal (GAS) disease among household contacts of persons with invasive GAS infections and for responding to postpartum and postsurgical invasive GAS infections. Experts reviewed data on the risk of subsequent invasive GAS infection among household contacts of case patients, the effectiveness of chemoprophylactic regimens for eradicating GAS carriage, and the epidemiology of postpartum and postsurgical GAS infection clusters. For household contacts of index patients, routine screening for and chemoprophylaxis against GAS are not recommended. Providers and public health officials may choose to offer chemoprophylaxis to household contacts who are at an increased risk of sporadic disease or mortality due to GAS. One nosocomial postpartum or postsurgical invasive GAS infection should prompt enhanced surveillance and isolate storage, whereas > or =2 cases caused by the same strain should prompt an epidemiological investigation that includes the culture of specimens from epidemiologically linked health care workers.

Unexplained reduced microbiological efficacy of intramuscular benzathine penicillin G and of oral penicillin V in eradication of group a streptococci from children with acute pharyngitis

OBJECTIVE

To evaluate the efficacy of oral penicillin V and intramuscular benzathine penicillin G (BPG) in eradicating group A streptococci from the upper respiratory tract.

METHODOLOGY

Two randomized, single-blind, multicenter antibiotic efficacy trials in children using recommended doses of either oral penicillin V or intramuscular BPG for treatment of acute-onset pharyngitis associated with isolation of group A streptococci were conducted. Throat examinations and cultures were obtained at enrollment and on days 5 to 8, 10 to 14, and 29 to 31.

RESULTS

Thirty-five percent of 284 evaluable patients treated with oral penicillin V and 37% of BPG-treated patients were microbiologic treatment failures at either 10 to 14 or 29 to 31 days.

CONCLUSIONS

Although these findings do not provide sufficient evidence to change current treatment recommendations or public health policy, important questions are raised about currently recommended penicillin doses, about the role of the carrier state, and possibly about adequate bioavailability of intramuscular BPG. These findings require confirmation.

Etiology and Management of Acute and Recurrent Group A Streptococcal Tonsillitis

Tonsillitis is one of the most prevalent infections in children and adolescents. The etiologic agents might be viral or bacterial. About 30% of cases are reported to be of bacterial origin, mainly due to group A Streptococcus (GAS). Although in most instances GAS tonsillitis is a self-limited disease, antibiotic treatment is recommended, mainly to prevent the suppurative and nonsuppurative poststreptococcal sequelae of acute rheumatic fever and to prevent glomerulonephritis. In this paper we review the current knowledge of the etiology of acute and recurrent GAS tonsillitis, with special emphasis on a recent hypothesis regarding the etiology of bacterial eradication failure. While penicillin V remains the drug of choice for acute tonsillitis, other antibiotics are being approved and recommended for particular indications in both Europe and the United States.