Penicillin failure in streptococcal tonsillopharyngitis: causes and remedies

Streptococcal Collagen-like Protein 1 Binds Wound Fibronectin: Implications in Pathogen Targeting

Group A Streptococcus (GAS) infections are responsible for significant morbidity and mortality worldwide. The outlook for an effective global vaccine is reduced because of significant antigenic variation among GAS strains worldwide. Other challenges in GAS therapy include the lack of common access to antibiotics in developing countries, as well as allergy to and treatment failures with penicillin and increasing erythromycin resistance in the industrialized world. At the portal of entry, GAS binds to newly deposited extracellular matrix, which is rich in cellular fibronectin isoforms with extra domain A (EDA, also termed EIIIA) via the surface adhesin, the streptococcal collagen-like protein 1 (Scl1). Recombinant Scl1 constructs, derived from diverse GAS strains, bind the EDA loop segment situated between the C and C' β-strands. Despite the sequence diversity in Scl1 proteins, multiple sequence alignments and secondary structure predictions of Scl1 variants, as well as crystallography and homology modeling studies, point to a conserved mechanism of Scl1-EDA binding. We propose that targeting this interaction may prevent the progression of infection. A synthetic cyclic peptide, derived from the EDA C-C' loop, binds to recombinant Scl1 with a micromolar dissociation constant. This review highlights the current concept of EDA binding to Scl1 and provides incentives to exploit this binding to treat GAS infections and wound colonization.

Management of children with persistent group A streptococcal carriage

INTRODUCTION

Chronic GAS carrier state is best defined as the prolonged presence of group A β-haemolytic Streptococcus (GAS) in the pharynx without evidence of infection or inflammation. Chronic GAS carriers have a low risk of immune mediated complications. Persistent pharyngeal carriage often raises management issues. In this study, we review the evidence on the management of persistent GAS carriage in children and propose a management algorithm. Areas covered: Chronic GAS pharyngeal carriage is quite common affecting 10-20% of school-aged children. Pathogenesis of carriage has been related to the pharynx microflora and to special properties of GAS, but several aspects are yet to be elucidated. Management greatly depends on whether the individual child belongs to a 'high-risk' group and might benefit from eradication regimens or not, when observation-only and reassurance are enough. Penicillin plus rifampin and clindamycin monotherapy have been recommended for eradication; limited evidence of effectiveness of azithromycin has been reported. Surgical intervention is not indicated. Expert commentary: GAS infection is a common reason for antibiotic use and abuse in children and asymptomatic carriers constitute the major reservoir of GAS in the community. Several aspects are yet to be elucidated and well-designed studies are needed for firm conclusions to be drawn.

Hostage to History: The Duration of Antimicrobial Treatment for Acute Streptococcal Pharyngitis

Oral antimicrobial treatment of acute streptococcal pharyngitis commonly is given for 10 days. An investigation was conducted of journal publications and textbooks from the dawn of the antimicrobial era to the present in order to discover the basis for this settled practice. Current treatment duration for acute streptococcal pharyngitis was established half a century ago under conditions significantly different from those currently encountered by the average clinician. The 10-day treatment standard evolved without scientific justification. There have been no therapeutic trials that have validated the necessity for 10 days of oral antimicrobial treatment. Yet, despite the lack of a scientific foundation, the rarity of acute rheumatic fever in developed countries, the high failure rate for streptococcal eradication and evidence that short-course therapy with a nonpenicillin antimicrobial yields equivalent eradication rates, the 10-day rule persists because of long clinical usage and the inherent power of the number 10. Efforts to change this clinical benchmark will likely meet with resistance from practicing physicians.

In Vitro Antimicrobial Activity of Thymus vulgaris Essential Oil Against Major Oral Pathogens

The objective of present investigation was to determine antimicrobial activity of Thymus vulgaris oil on some oral pathogens. Thymus vulgaris oil was prepared by hydrodistillation and tested against 30 clinical isolates of each of Streptococcus pyogenes, Streptococcus mutans, Candida albicans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans, prepared from related oral infections using agar disk diffusion and broth microdilution methods. Thymus vulgaris oil at concentrations of 16 to 256 μg/mL exhibited strong inhibitory activity on all clinical isolates producing inhibition zones of 7.5 to 42 mm as measured by agar disk diffusion method. Streptococcus pyogenes and Streptococcus mutans were the most sensitive isolates with minimum inhibitory concentrations of 1.9 and 3.6 μg/mL, respectively. The minimum inhibitory concentration values for C albicans, A actinomycetemcomitans, and P gingivalis were 16.3, 32, and 32 μg/mL, respectively.

Application of an enzyme-labeled antigen method for visualizing plasma cells producing antibodies against Strep A, a carbohydrate antigen of Streptococcus pyogenes, in recurrent tonsillitis

Streptococcus pyogenes is the main causative pathogen of recurrent tonsillitis. Histologically, lesions of recurrent tonsillitis contain numerous plasma cells. Strep A is an antigenic carbohydrate molecule on the cell wall of S. pyogenes. As expected, plasma cells in subjects with recurrent tonsillitis secrete antibodies against Strep A. The enzyme‐labeled antigen method is a novel histochemical technique that visualizes specific antibody‐producing cells in tissue sections by employing a biotin‐labeled antigen as a probe. The purpose of the present study was to visualize plasma cells producing antibodies reactive with Strep A in recurrent tonsillitis. Firstly, the lymph nodes of rats immunized with boiled S. pyogenes were paraformaldehyde‐fixed and specific plasma cells localized in frozen sections with biotinylated Strep A. Secondly, an enzyme‐labeled antigen method was used on human tonsil surgically removed from 12 patients with recurrent tonsillitis. S. pyogenes genomes were PCR‐detected in all 12 specimens. The emm genotypes belonged to emm12 in nine specimens and emm1 in three. Plasma cells producing anti‐Strep A antibodies were demonstrated in prefixed frozen sections of rat lymph nodes, 8/12 human specimens from patients with recurrent tonsillitis but not in two control tonsils. In human tonsils, Strep A‐reactive plasma cells were observed within the reticular squamous mucosa and just below the mucosa, and the specific antibodies belonged to either IgA or IgG classes. Our technique is effective in visualizing immunocytes producing specific antibodies against the bacterial carbohydrate antigen, and is thus a novel histochemical tool for analyzing immune reactions in infectious disorders.

Identification of Quorum-Sensing Inhibitors Disrupting Signaling between Rgg and Short Hydrophobic Peptides in Streptococci

Bacteria coordinate a variety of social behaviors, important for both environmental and pathogenic bacteria, through a process of intercellular chemical signaling known as quorum sensing (QS). As microbial resistance to antibiotics grows more common, a critical need has emerged to develop novel anti-infective therapies, such as an ability to attenuate bacterial pathogens by means of QS interference. Rgg quorum-sensing pathways, widespread in the phylum Firmicutes, employ cytoplasmic pheromone receptors (Rgg transcription factors) that directly bind and elicit gene expression responses to imported peptide signals. In the human-restricted pathogen Streptococcus pyogenes, the Rgg2/Rgg3 regulatory circuit controls biofilm development in response to the short hydrophobic peptides SHP2 and SHP3. Using Rgg-SHP as a model receptor-ligand target, we sought to identify chemical compounds that could specifically inhibit Rgg quorum-sensing circuits. Individual compounds from a diverse library of known drugs and drug-like molecules were screened for their ability to disrupt complexes of Rgg and FITC (fluorescein isothiocyanate)-conjugated SHP using a fluorescence polarization (FP) assay. The best hits were found to bind Rgg3 in vitro with submicromolar affinities, to specifically abolish transcription of Rgg2/3-controlled genes, and to prevent biofilm development in S. pyogenes without affecting bacterial growth. Furthermore, the top hit, cyclosporine A, as well as its nonimmunosuppressive analog, valspodar, inhibited Rgg-SHP pathways in multiple species of Streptococcus. The Rgg-FITC-peptide-based screen provides a platform to identify inhibitors specific for each Rgg type. Discovery of Rgg inhibitors constitutes a step toward the goal of manipulating bacterial behavior for purposes of improving health.

The global emergence of antibiotic-resistant bacterial infections necessitates discovery not only of new antimicrobials but also of novel drug targets. Since antibiotics restrict microbial growth, strong selective pressures to develop resistance emerge quickly in bacteria. A new strategy to fight microbial infections has been proposed, namely, development of therapies that decrease pathogenicity of invading organisms while not directly inhibiting their growth, thus decreasing selective pressure to establish resistance. One possible means to this goal is to interfere with chemical communication networks used by bacteria to coordinate group behaviors, which can include the synchronized expression of genes that lead to disease. In this study, we identified chemical compounds that disrupt communication pathways regulated by Rgg proteins in species of Streptococcus. Treatment of cultures of S. pyogenes with the inhibitors diminished the development of biofilms, demonstrating an ability to control bacterial behavior with chemicals that do not inhibit growth.

Streptolysin O and its co-toxin NAD-glycohydrolase protect group A Streptococcus from Xenophagic killing

Group A Streptococcus (Streptococcus pyogenes or GAS) causes pharyngitis, severe invasive infections, and the post-infectious syndromes of glomerulonephritis and rheumatic fever. GAS can be internalized and killed by epithelial cells in vitro, a process that may contribute to local innate defense against pharyngeal infection. Secretion of the pore-forming toxin streptolysin O (SLO) by GAS has been reported to stimulate targeted autophagy (xenophagy) upon internalization of the bacteria by epithelial cells. Whereas this process was associated with killing of GAS in HeLa cells, studies in human keratinocytes found SLO production enhanced intracellular survival. To reconcile these conflicting observations, we now report in-depth investigation of xenophagy in response to GAS infection of human oropharyngeal keratinocytes, the predominant cell type of the pharyngeal epithelium. We found that SLO expression was associated with prolonged intracellular survival; unexpectedly, expression of the co-toxin NADase was required for this effect. Enhanced intracellular survival was lost upon deletion of NADase or inactivation of its enzymatic activity. Shortly after internalization of GAS by keratinocytes, SLO-mediated damage to the bacteria-containing vacuole resulted in exposure to the cytosol, ubiquitination of GAS and/or associated vacuolar membrane remnants, and engulfment of GAS in LC3-positive vacuoles. We also found that production of streptolysin S could mediate targeting of GAS to autophagosomes in the absence of SLO, a process accompanied by galectin 8 binding to damaged GAS-containing endosomes. Maturation of GAS-containing autophagosome-like vacuoles to degradative autolysosomes was prevented by SLO pore-formation and by SLO-mediated translocation of enzymatically active NADase into the keratinocyte cytosol. We conclude that SLO stimulates xenophagy in pharyngeal keratinocytes, but the coordinated action of SLO and NADase prevent maturation of GAS-containing autophagosomes, thereby prolonging GAS intracellular survival. This novel activity of NADase to block autophagic killing of GAS in pharyngeal cells may contribute to pharyngitis treatment failure, relapse, and chronic carriage.

Group A Streptococcus (Streptococcus pyogenes or GAS) is the agent of streptococcal pharyngitis (strep throat), invasive infections such as necrotizing fasciitis and streptococcal toxic shock, and post-infectious complications including rheumatic heart disease. Epithelial cells internalize and kill GAS in vitro and may contribute to local innate immune defense in the human pharynx. We now find that production of the secreted pore-forming toxin streptolysin O (SLO) triggered targeted autophagy (termed xenophagy) of GAS in human oropharyngeal keratinocytes, but also enhanced GAS intracellular survival. Increased GAS survival was dependent both on pore-formation by SLO and on SLO-mediated translocation of an enzymatically active co-toxin, NAD-glycohydrolase, into the keratinocyte cytosol. The survival-enhancing effect of both toxins was associated with inhibition of lysosomal fusion with GAS-containing autophagosomes to form functional degradative autolysosomes. These findings reveal a novel coordinated role of two streptococcal toxins in protecting GAS from xenophagic killing and enhancing intracellular survival. Prolonged GAS intracellular survival may contribute to pharyngitis treatment failure, relapse, and chronic carriage.

Recurrences in chronic tonsillitis substained by tonsillar biofilm-producing bacteria in children. Relationship with the grade of tonsillar hyperplasy

OBJECTIVES

It has been suggested that bacterial biofilms are involved in chronic tonsillar disease, but there is a lack of strong evidence concerning their etiopathogenic role in childhood chronic tonsillar infections. The aim of this study was to assess the presence of biofilm-producing bacteria (BPB) in tonsillar bioptic specimens taken from children with recurrent exacerbations of chronic hyperplastic tonsillitis, and to evaluate the possible relationship between them and the patients' demographic and clinical characteristics.

METHODS

22 children (68.2% males; median age 6.5 years, range 3-13) with recurrent exacerbations of chronic hyperplastic tonsillitis were included. The presence of tonsillar BPB was assessed by means of the spectrophotometric analysis of tonsillar bioptic specimens taken during tonsillectomy between episodes of tonsillar infection.

RESULTS

BPB were found in 50.0% of the 44 tonsillar specimens, and Staphylococcus aureus was the most frequent pathogen (81.8%). There was a significant relationship (p=0.02) between the grade of tonsillar hyperplasy (GTH) and the presence of tonsillar BPB, with an increased relative risk (RR=4.27, standard error=2.57, p<0.01) of tonsillar BPB development in children with GTH scores of >2.

CONCLUSIONS

The findings of this study: (1) confirm the presence of tonsillar BPB in children with recurrent exacerbations of chronic tonsillar infections; (2) suggest that GTH is an important indicator of the presence of tonsillar BPB; and (3) raise the question as to whether tonsillar biofilm is a causative factor or just a consequence of recurrent exacerbations of chronic hyperplastic tonsillitis.

Antibacterial Activity of Rhodomyrtus tomentosa (Aiton) Hassk. Leaf Extract against Clinical Isolates of Streptococcus pyogenes

Ethanol extract of Rhodomyrtus tomentosa (Aiton) Hassk. leaf was evaluated for antibacterial activity against 47 clinical isolates of Streptococcus pyogenes. The extract exhibited good anti-S. pyogenes activity against all the tested isolates with similar minimum inhibitory concentration (MIC, 3.91-62.5 μg mL(-1)) and minimum bactericidal concentration (MBC, 3.91-62.5 μg mL(-1)) ranges. No surviving cells were detected at 16 h after treatment with 8 × MIC of the extract. The extract-treated cells demonstrated no lysis and cytoplasmic leakage through the bacterial membrane. Electron micrographs further revealed that the extract did not cause any dramatic changes on the treated cells. Rhodomyrtone, an isolated compound, exhibited good anti-S. pyogenes activity (14 isolates), expressed very low MIC (0.39-1.56 μg mL(-1)) and MBC (0.39-1.56 μg mL(-1)) values. Rhodomyrtus tomentosa leaf extract and rhodomyrtone displayed promising antibacterial activity against clinical isolates of S. pyogenes.

Streptococcal pharyngitis: a prospective study of compliance and complications

Background. Uncertainty exists concerning the necessity of 10-day antibiotic treatment of group A beta hemolytic streptococcus (GABHS) pharyngitis. Objective. To assess the incidence of GABHS recurrence and suppurative and nonsuppurative complications in relation to compliance. Methods. (Design). Prospective cohort observational study. (Subjects). 2,000 children aged 6 months to 18 years with sore throat and positive GABHS culture. (Main Outcome Measures). Recurrence of symptomatic culture positive GABHS pharyngitis, incidence of suppurative, and long-term, regional, nonsuppurative complications of GABHS pharyngitis, over a ten year period. Results. 213 (11%) of the children received no treatment. Most children received antibiotics for only 4-6 days (in correlation with the duration of fever, which in most cases lasted up to 3 days). Three hundred and six (15.3%) children had clinically diagnosed recurrent tonsillopharyngitis; 236 (12.3%) had positive GABHS findings within 10 to 14 days and thirty-four (1.7%) within 21-30 days after the index positive GABHS culture. The remaining 1.3% had no positive culture despite the clinical findings. Almost all recurrences [236 (11.6%)] occurred within 14 days and 156 (7.6%) in the fully treated group. The presence of fever during the first 3 days of the disease was the most significant predictor for recurrence. Other predictors were the age younger than 6 years and the presence of cervical lymphadenitis. No increase in the incidence of nonsuppurative or suppurative complications was noted during the 10-year follow-up period, compared to the past incidence of those complications in Israel. Conclusions. Our data suggests that the majority of children discontinue antibiotics for GABHS tonsillopharyngitis a day or two after the fever subsides. The incidence of complications in our study was not affected by this poor compliance.

Detection of group A Streptococcus in tonsils from pediatric patients reveals high rate of asymptomatic streptococcal carriage

Background

Group A Streptococcus (GAS) causes acute tonsillopharyngitis in children, and approximately 20% of this population are chronic carriers of GAS. Antibacterial therapy has previously been shown to be insufficient at clearing GAS carriage. Bacterial biofilms are a surface-attached bacterial community that is encased in a matrix of extracellular polymeric substances. Biofilms have been shown to provide a protective niche against the immune response and antibiotic treatments, and are often associated with recurrent or chronic bacterial infections. The objective of this study was to test the hypothesis that GAS is present within tonsil tissue at the time of tonsillectomy.

Methods

Blinded immunofluorescent and histological methods were employed to evaluate palatine tonsils from children undergoing routine tonsillectomy for adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis.

Results

Immunofluorescence analysis using anti-GAS antibody was positive in 11/30 (37%) children who had tonsillectomy for adenotonsillar hypertrophy and in 10/30 (33%) children who had tonsillectomy for recurrent GAS pharyngitis. Fluorescent microscopy with anti-GAS and anti-cytokeratin 8 & 18 antibodies revealed GAS was localized to the tonsillar reticulated crypts. Scanning electron microscopy identified 3-dimensional communities of cocci similar in size and morphology to GAS. The characteristics of these communities are similar to GAS biofilms from in vivo animal models.

Conclusion

Our study revealed the presence of GAS within the tonsillar reticulated crypts of approximately one-third of children who underwent tonsillectomy for either adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis at the Wake Forest School of Medicine.

Trial Registration

The tissue collected was normally discarded tissue and no patient identifiers were collected. Thus, no subjects were formally enrolled.

Potential antibiotic and anti-infective effects of rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. on Streptococcus pyogenes as revealed by proteomics

Rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. leaf extract has a strong antibacterial activity against the bacterial pathogen Streptococcus pyogenes. Our previous studies indicated that the bactericidal activity of rhodomyrtone might involve intracellular targets. In the present studies we followed a proteomics approach to investigate the mode of action of rhodomyrtone on S. pyogenes. For this purpose, S. pyogenes was cultivated in the presence of 0.39 μg/ml rhodomyrtone, which corresponds to 50% of the minimal inhibitory concentration. The results show that the amounts of various enzymes associated with important metabolic pathways were strongly affected, which is consistent with the growth-inhibiting effect of rhodomyrtone. Additionally, cells of S. pyogenes grown in the presence of rhodomyrtone produced reduced amounts of known virulence factors, such as the glyceraldehyde-3-phosphate dehydrogenase, the CAMP factor, and the streptococcal pyrogenic exotoxin C. Taken together, these findings indicate that rhodomyrtone has both antimicrobial and anti-infective activities, which make it an interesting candidate drug.

Comparative Study of 5-Day and 10-Day Cefditoren Pivoxil Treatments for Recurrent Group A beta-Hemolytic Streptococcus pharyngitis in Children

Efficacy of short-course therapy with cephalosporins for treatment of group A beta-hemolytic streptococcus (GABHS) pharyngitis is still controversial. Subjects were 226 children with a history of at least one episode of GABHS pharyngitis. Recurrence within the follow-up period (3 weeks after initiation of therapy) occurred in 7 of the 77 children in the 5-day treatment group and in 1 of the 149 children in the 10-day treatment group; the incidence of recurrence being significantly higher in the 5-day treatment group. Bacteriologic treatment failure (GABHS isolation without overt pharyngitis) at follow-up culture was observed in 7 of the 77 children in the 5-day treatment group and 17 of the 149 children in the 10-day treatment group. There was no statistical difference between the two groups. A 5-day course of oral cephalosporins is not always recommended for treatment of GABHS pharyngitis in children who have repeated episodes of pharyngitis.

Beta-lactam effects on mixed cultures of common respiratory isolates as an approach to treatment effects on nasopharyngeal bacterial population dynamics

Background

Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae are bacteria present in the nasopharynx as part of normal flora. The ecological equilibrium in the nasopharynx can be disrupted by the presence of antibiotics.

Methodology/Principal Findings

A computerized two-compartment pharmacodynamic model was used to explore β-lactam effects on the evolution over time of a bacterial load containing common pharyngeal isolates by simulating free serum concentrations obtained with amoxicillin (AMX) 875 mg tid, amoxicillin/clavulanic acid (AMC) 875/125 mg tid and cefditoren (CDN) 400 mg bid regimens over 24 h. Strains and MICs (µg/ml) of AMX, AMC and CDN were: S. pyogenes (0.03, 0.03 and 0.015), S. pneumoniae (2, 2 and 0.25), a β-lactamase positive H. influenzae (BL⁺; >16, 2 and 0.06) and a β-lactamase positive AMC-resistant H. influenzae (BLPACR, >16, 8 and 0.06). Mixture of identical 1∶1∶1∶1 volumes of each bacterial suspension were prepared yielding an inocula of ≈4×10⁶ cfu/ml. Antibiotic concentrations were measured both in bacterial and in bacteria-free antibiotic simulations. β-lactamase production decreased AMX concentrations and fT_>MIC against S. pneumoniae (from 43.2% to 17.7%) or S. pyogenes (from 99.9% to 24.9%), and eradication was precluded. The presence of clavulanic acid countered this effect of co-pathogenicity, and S. pyogenes (but not BL⁺ and S. pneumoniae) was eradicated. Resistance of CDN to TEM β-lactamase avoided this co-pathogenicity effect, and CDN eradicated S. pyogenes and H. influenzae strains (fT_>MIC >58%), and reduced in 94% S. pneumoniae counts (fT_>MIC ≈25%).

Conclusions/Significance

Co-pathogenicity seems to be gradual since clavulanic acid countered this effect for strains very susceptible to AMX as S. pyogenes but not for strains with AMX MIC values in the limit of susceptibility as S. pneumoniae. There is a potential therapeutic advantage for β-lactamase resistant cephalosporins with high activity against streptococci.

Clinical efficacy of dexamethasone for acute exudative pharyngitis

The objective of this study was to investigate whether treatment with single-dose dexamethasone can provide relief of symptoms in acute exudative pharyngitis. A prospective, randomized, double-blinded, placebo-controlled clinical trial was undertaken over a 3-month period in a university-based Emergency Department. The study included all consecutive patients between 18 and 65 years of age presenting with acute exudative pharyngitis, sore throat, odynophagia, or a combination, and with more than two Centor criteria. Each patient was empirically treated with azithromycin and paracetamol for 3 days. The effects of placebo and a fixed single dose (8 mg) of intramuscular injection of dexamethasone were compared. The patients were asked to report the exact time to onset of pain relief and time to complete relief of pain. After completion of the treatment, telephone follow-up regarding the relief of pain was conducted. A total of 103 patients were enrolled. Thirty patients with a history of recent antibiotic use, pregnancy, those who were elderly (>65 years of age) and patients who failed to give informed consent were excluded. Forty-two patients were assigned to the placebo group and 31 were assigned to the intramuscular dexamethasone group (8-mg single dose). Time to perceived onset of pain relief was 8.06+/-4.86 h in steroid-treated patients, as opposed to 19.90+/-9.39 h in the control group (p=0.000). The interval required to become pain-free was 28.97+/-12.00 h in the dexamethasone group, vs. 53.74+/-16.23 h in the placebo group (p=0.000). No significant difference was observed in vital signs between the regimens. No side effects and no new complaints attributable to the dexamethasone and azithromycin were observed. Sore throat and odynophagia in patients with acute exudative pharyngitis may respond better to treatment with an 8-mg single dose of intramuscular dexamethasone accompanied by an antibiotic regimen than to antibiotics alone.

Beta-lactam failure in treatment of two group G Streptococcus dysgalactiae subsp. equisimilis Pharyngitis patients

We present two cases of exudative pharyngitis due to Streptococcus dysgalactiae subsp. equisimilis, Lancefield group G. While the participation of this organism as an agent of pharyngitis is well documented, we focus on failure of beta-lactam therapy, a phenomenon that is well described for pharyngitis due to Streptococcus pyogenes. Therefore, these case reports add to our knowledge of pharyngitis caused by non-S. pyogenes streptococci.

The evidence base for cephalosporin superiority over penicillin in streptococcal pharyngitis

Current treatment guidelines from the Infectious Diseases Society of America, the American Heart Association, and the American Academy of Pediatrics recommend only oral penicillin V or intramuscular benzathine penicillin G as the drugs of choice for treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis. Ten-day treatment courses with 1st-generation oral cephalosporins or erythromycin are recommended as suitable alternatives in patients who are allergic to penicillin. Despite these recommendations, oral cephalosporins are used as drugs of choice for many patients with GABHS pharyngitis. Simpler and/or short-course regimens of cephalosporins that have been approved by the Food and Drug Administration offer alternatives with the potential for unchanged patient compliance. Increasing cephalosporin use in patients with GABHS pharyngitis has followed from numerous reports and metaanalyses of cephalosporin superiority over penicillin for bacteriologic eradication and clinical response. This review examines the evidence supporting the use of cephalosporins as a first choice of treatment for many patients with GABHS pharyngitis.

The appropriate management of pharyngitis in children and adults

Acute pharyngitis, or the complaint of a sore throat, is one of the most common illnesses for which both adult and pediatric patients seek medical care from primary care physicians. In the USA, acute pharyngitis accounts for 1-2% of all visits to outpatient departments, physician offices and emergency departments. There are multiple etiologic agents that can cause pharyngitis, and strategies for diagnosis and treatment should be directed at identifying those causes of pharyngitis that require antimicrobial therapy. In some cases, the decision as to which patients to treat with antibiotics remains difficult. This article reviews some of the various causes of pharyngitis and the available therapeutic options.

Explaining the poor bacteriologic eradication rate of single-dose ceftriaxone in group a streptococcal tonsillopharyngitis: a reverse engineering solution using pharmacodynamic modeling

OBJECTIVE

To explore pharmacokinetic factors underlying the poor bacteriologic eradication rate with a single 500-mg dose of ceftriaxone for streptococcal tonsillopharyngitis and to identify the minimum ceftriaxone dose required for effective treatment.

METHODS

Population modeling techniques were applied to pharmacokinetic data derived from paired plasma and tonsil samples from 153 children to assess the contribution of pharmacokinetic variability to patients' responses to ceftriaxone. In addition, a Monte Carlo simulation was performed to determine (1) the amount of time that free ceftriaxone concentrations must exceed the minimum inhibitory concentration (MIC) of group A Streptococcus to achieve bacteriologic eradication and (2) the ceftriaxone dose required to maintain free drug concentrations above the target MIC for the requisite amount of time. Ceftriaxone MICs for group A Streptococcus were obtained from a previous trial, in which all MICs (n = 115) were < or = 0.064 mg/L; 33.9% were susceptible at < or = 0.016 mg/L, 66.4% were susceptible at 0.032 mg/L, and 1.7% were susceptible at 0.064 mg/L.

RESULTS

Mean population pharmacokinetic parameters and their variances reflected substantial variability of clearance and half-life in the target population. Tonsillar ceftriaxone protein binding was 89.1%. The proportions of 1000 simulated patients with free ceftriaxone concentrations that exceeded MICs of 0.016 mg/L, 0.032 mg/L, and 0.064 mg/L at 24 hours were 71.7%, 65.4%, and 57.2%, respectively, and at 48 hours were 41.8%, 35.8%, and 28.6%, respectively. The amount of time that free ceftriaxone concentrations need to exceed MIC to achieve bacteriologic success was estimated to be 36 hours. Using this time criterion, two 500-mg doses of ceftriaxone separated by 18 hours should achieve a bacteriologic cure rate of approximately 95%.

CONCLUSIONS

Pharmacokinetic variability and high ceftriaxone tonsillar protein binding explain the high microbiologic failure rate for a single 500-mg dose of ceftriaxone in group A streptococcal tonsillopharyngitis. Monte Carlo simulation suggests that a second dose administered 18 hours after the first will be required to achieve an acceptable bacteriologic cure rate.

Antimicrobial susceptibility trends among Escherichia coli and Shigella spp. isolated from rural Egyptian paediatric populations with diarrhoea between 1995 and 2000

Antimicrobial susceptibility testing was performed on 3,627 isolates of Escherichia coli and 180 isolates of Shigella spp. collected in rural locations from 875 Egyptian children with diarrhoea between 1995 and 2000. The cumulative rates of resistance for E. coli and Shigella spp. were high (respectively, 68.2% and 54.8% for ampicillin, 24.2% and 23.5% for ampicillin-sulbactam, 57.2% and 42.5% for trimethoprim-sulphamethoxazole, and 50.9% and 75.4% for tetracycline). Non-enterotoxigenic E. coli (NETEC) isolates had a consistently higher level of antimicrobial resistance than did enterotoxigenic E. coli (ETEC) isolates. Trend testing showed significant decreases in resistance to ampicillin, ampicillin-sulbactam and tetracycline among all E. coli isolates. Increasing rates of resistance were observed for trimethoprim-sulphamethoxazole in ETEC isolates and Shigella spp., but not in NETEC isolates. Low levels of resistance were observed for all other antimicrobial agents tested. Overall, high levels, but decreasing trends, of resistance to commonly used antimicrobial agents were detected among isolates of E. coli and Shigella spp. from children in rural Egypt.

Evaluation of 5-day therapy with telithromycin, a novel ketolide antibacterial, for the treatment of tonsillopharyngitis

A pooled analysis of two double-blind, multicentre, Phase III studies compared oral telithromycin 800 mg once-daily for 5 days with penicillin V 500 mg three-times-daily or clarithromycin 250 mg twice-daily for 10 days in the treatment of Streptococcus pyogenes (group A beta-haemolytic streptococcus; GABHS) tonsillopharyngitis. Patients aged > or = 13 years with acute GABHS tonsillopharyngitis were randomised to receive telithromycin (n = 430), penicillin (n = 197) or clarithromycin (n = 231). Clinical isolates of S. pyogenes (n = 590) obtained from throat swab samples on study entry were tested for their in-vitro susceptibility to telithromycin, clarithromycin and azithromycin. Telithromycin demonstrated in-vitro activity against the clinical isolates of S. pyogenes (MIC50/90 0.03/0.06 mg/L) higher than clarithromycin or azithromycin (MIC50/90 0.06/0.06 mg/L and 0.12/0.25 mg/L, respectively), including erythromycin-resistant strains. At the post-therapy/test of cure (TOC) visit (days 16-23), satisfactory bacteriological outcome was demonstrated for 88.3% (234/265) and 88.6% (225/254) of telithromycin- and comparator-treated patients, respectively (per-protocol population). Overall, GABHS eradication rates were 88.7% (235/265) for telithromycin and 89.0% (226/254) for comparators. The clinical cure rates at the post-therapy/TOC visit were 93.6% (248/265) and 90.9% (220/242) for telithromycin and pooled comparators, respectively. Telithromycin was generally well-tolerated. Most adverse events considered to be possibly related to study medication were gastrointestinal and of mild intensity. Discontinuations as a result of adverse events were few in both treatment groups. In conclusion, telithromycin 800 mg once-daily for 5 days was as effective as penicillin V or clarithromycin for 10 days in the treatment of GABHS tonsillopharyngitis.

Meta-analysis of Cephalosporins versus Penicillin for Treatment of Group A Streptococcal Tonsillopharyngitis in Adults

We conducted a meta-analysis of 9 randomized controlled trials (involving 2113 patients) comparing cephalosporins with penicillin for treatment of group A beta -hemolytic streptococcal (GABHS) tonsillopharyngitis in adults. The summary odds ratio (OR) for bacteriologic cure rate significantly favored cephalosporins, compared with penicillin (OR,1.83; 95% confidence interval [CI], 1.37-2.44); the bacteriologic failure rate was nearly 2 times higher for penicillin therapy than it was for cephalosporin therapy (P=.00004). The summary OR for clinical cure rate was 2.29 (95% CI, 1.61-3.28), significantly favoring cephalosporins (P<.00001). Sensitivity analyses for bacterial cure significantly favored cephalosporins over penicillin in trials that were double-blinded and of high quality, trials that had a well-defined clinical status, trials that performed GABHS serotyping, trials that eliminated carriers from analysis, and trials that had a test-of-cure culture performed 3-14 days after treatment. This meta-analysis indicates that the likelihood of bacteriologic and clinical failure in the treatment of GABHS tonsillopharyngitis is 2 times higher for oral penicillin than for oral cephalosporins.

Meta-analysis of cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis in children

OBJECTIVE

To conduct a meta-analysis of randomized, controlled trials of cephalosporin versus penicillin treatment of group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis in children.

METHODOLOGY

Medline, Embase, reference lists, and abstract searches were conducted to identify randomized, controlled trials of cephalosporin versus penicillin treatment of GABHS tonsillopharyngitis in children. Trials were included if they met the following criteria: patients <18 years old, bacteriologic confirmation of GABHS tonsillopharyngitis, random assignment to antibiotic therapy of an orally administered cephalosporin or penicillin for 10 days of treatment, and assessment of bacteriologic outcome using a throat culture after therapy. Primary outcomes of interest were bacteriologic and clinical cure rates. Sensitivity analyses were performed to assess the impact of careful clinical illness descriptions, compliance monitoring, GABHS serotyping, exclusion of GABHS carriers, and timing of the test-of-cure visit.

RESULTS

Thirty-five trials involving 7125 patients were included in the meta-analysis. The overall summary odds ratio (OR) for the bacteriologic cure rate significantly favored cephalosporins compared with penicillin (OR: 3.02; 95% confidence interval [CI]: 2.49-3.67, with the individual cephalosporins [cephalexin, cefadroxil, cefuroxime, cefpodoxime, cefprozil, cefixime, ceftibuten, and cefdinir] showing superior bacteriologic cure rates). The overall summary OR for clinical cure rate was 2.33 (95% CI: 1.84-2.97), significantly favoring the same individual cephalosporins. There was a trend for diminishing bacterial cure with penicillin over time, comparing the trials published in the 1970s, 1980s, and 1990s. Sensitivity analyses for bacterial cure significantly favored cephalosporin treatment over penicillin treatment when trials were grouped as double-blind (OR: 2.31; 95% CI: 1.39-3.85), high-quality (OR: 2.50; 95% CI: 1.85-3.36) trials with well-defined clinical status (OR: 2.12; 95% CI: 1.54-2.90), with detailed compliance monitoring (OR: 2.85; 95% CI: 2.33-3.47), with GABHS serotyping (OR: 3.10; 95% CI: 2.42-3.98), with carriers eliminated (OR: 2.51; 95% CI: 1.55-4.08), and with test of cure 3 to 14 days posttreatment (OR: 3.53; 95% CI: 2.75-4.54). Analysis of comparative bacteriologic cure rates for the 3 generations of cephalosporins did not show a difference.

CONCLUSIONS

This meta-analysis indicates that the likelihood of bacteriologic and clinical failure of GABHS tonsillopharyngitis is significantly less if an oral cephalosporin is prescribed, compared with oral penicillin.

Optimizing antibacterial therapy for community-acquired respiratory tract infections in children in an era of bacterial resistance

The spread of antibacterial resistance in bacteria that commonly cause childhood community-acquired respiratory tract infections (RTIs), such as acute otitis media, community-acquired pneumonia, and acute pharyngitis, is a major healthcare problem. One of the foremost concerns is the rapid increase in penicillin, macrolide, and multidrug resistance in Streptococcus pneumoniae. There is also a rising prevalence of macrolide resistance in Streptococcus pyogenes in pockets of the United States, and beta-lactamase production in Haemophilus influenzae is widespread. Although data are limited, some evidence suggests that resistance to antibacterials can impair bacteriologic and clinical outcomes in childhood RTIs. Optimizing antibacterial use is important both in the care of individual patients and within strategies to address the wider problem of antibacterial resistance. This involves encouraging judicious antibacterial use (i.e., reducing overuse for viral infection and prophylaxis), and preventing misuse through the wrong choice, dosage, and duration of therapy. Given that initial therapy is usually empiric, antibacterials used to treat community-acquired RTIs in children should ideally have the following properties: an optimal targeted spectrum of activity; high clinical and bacteriologic efficacy against respiratory pathogens, including resistant strains; simple, short-course therapy; and good tolerability and palatability. New antibacterials will continue to have a role in the treatment of RTIs in children, especially where resistance compromises existing therapies.

Acute Streptococcal Tonsillopharyngitis: A Review of Clinical Efficacy and Bacteriological Eradication

This review evaluates studies published between January 1997 and August 2003 comparing clinical outcome and bacteriological eradication rates for patients with acute streptococcal tonsillopharyngitis treated with penicillin or other antimicrobial agents. Studies were identified using MEDLINE, and clinical outcome and bacteriological eradication at end of treatment and 2 weeks after end of treatment were ascertained. Any longer-term follow-up was also noted, along with treatment-related adverse events and compliance. Clinical efficacy rates between penicillin and comparator antibiotics were generally high and similar. Bacterial eradication rates were more variable and, 2 weeks after treatment, ranged from 64% to 93% for penicillin and 31% to 98% for comparators. Simpler dosing schedules and shorter therapy durations produced higher compliance rates. This review highlights the similarities and differences between treatment with penicillin and a wide range of comparator antibiotics. Therapy for acute group A streptococcal pharyngitis should combine excellent clinical efficacy, high bacteriological eradication rates, good tolerance and a simple, convenient dosing regimen.

Defining the optimum treatment regimen for azithromycin in acute tonsillopharyngitis

Pharyngitis is one of the most common infectious diseases affecting children. Group A streptococci are the leading bacterial cause of pharyngitis in children and adults. Because inappropriate antibiotic treatment for pharyngitis is becoming a major issue, only true group A beta-hemolytic streptococcus (GABHS) infections, proven by rapid antigen test or culture, should be treated with antibiotics. GABHS pharyngitis is often a mild and self-limiting infection in the absence of antimicrobial therapy. However, antimicrobial treatment must be administered to eradicate the pathogen from the throat, limit the spread of the infection and prevent possible progression to rheumatic fever, suppurative disease or toxin-mediated complications. Penicillin V for 10 days is the standard therapy and is effective in the management of GABHS pharyngitis. However, there are drawbacks to penicillin V therapy, including the length of the dosing regimen, which are leading to decreasing penicillin prescription rates in many countries. In addition bacteriologic treatment failures have been documented in up to 35% of GABHS patients treated with penicillin V, particularly in children <6 years old. A number of mechanisms may be responsible for these failures, but poor compliance with the standard 10-day penicillin treatment is likely to be a major factor. There is growing evidence to suggest that children with GABHS pharyngitis can be effectively treated with non-penicillin V antibiotics, which have the advantage of simpler and shorter dosing regimens compared with penicillin V. Among the antibiotics that have been tested clinically, azithromycin is the most widely studied. A total dose of 60 mg/kg azithromycin, given either as 12 mg/kg once daily for 5 days or 20 mg/kg once daily for 3 days, provides the best rate of GABHS eradication. Thus a total dose of 60 mg/kg azithromycin given during 3 or 5 days constitutes an alternative treatment to standard penicillin therapy in cases of penicillin hypersensitivity, when patient nonadherence to a 10-day penicillin regimen is suspected or for patients who fail therapy with a beta-lactam.

Short-course antimicrobial therapy of streptococcal pharyngitis

While penicillin administered orally or intramuscularly is the least expensive course of pharyngitis treatment, there are many limitations to its use. These include the need for extended treatment (i.e., 10 days) and poor palatability of its liquid formulation and an alarming increase in the rates of failure with standard doses of either IM or oral penicillin. Increasing rates of beta-lactamase-producing normal flora and eradication of protective alpha-streptococci may also play a role in penicillin treatment failure. Thus practitioners may consider switching to amoxicillin in higher doses (up to 40 to 60 mg/kg/day divided twice daily, maximum dose 1 gram twice daily) as first-line therapy (Figure 1), similar to what we have done for acute otitis media. Five-day short-course treatment with cefdinir or cefpodoxime may be suitable alternatives, especially in patients with penicillin hypersensitivity (not anaphylaxis). Concerns with higher costs of these second-line agents and potential for resistance must be balanced with concerns for patient adherence with penicillin treatment and the recent increasing rate of penicillin failures. In light of recent reports regarding the high rate of failure with azithromycin and increasing macrolide resistance, clinicians should prescribe standard doses of this drug for 5 days with caution.

Efficacy and tolerability of 5-day, once-daily telithromycin compared with 10-day, twice-daily clarithromycin for the treatment of group A beta-hemolytic streptococcal tonsillitis/pharyngitis: a multicenter, randomized, double-blind, parallel-group study

BACKGROUND

Telithromycin, a ketolide antibacterial, has been developed for the treatment of community-acquired respiratory infections.

OBJECTIVE

This study compared the efficacy and tolerability of 5-day, once-daily telithromycin with 10-day, twice-daily clarithromycin in adolescents and adults with acute tonsillitis/pharyngitis caused by group A beta-hemolytic streptococci ([GABHS] Streptococcus pyogenes).

METHODS

In this multicenter, randomized, double-blind, parallel-group study, adolescent (aged > or = 13 years) and adult patients with a diagnosis of GABHS tonsillitis/pharyngitis received once-daily telithromycin 800 mg for 5 days (followed by placebo for 5 days) or twice-daily clarithromycin 250 mg for 10 days. Bacteriologic and clinical outcomes were assessed at a test-of-cure visit (days 16 to 23) and a late posttherapy visit (days 31 to 45).

RESULTS

A total of 526 patients were enrolled in the study, of which 463 (288 females, 175 males) were randomized to receive treatment (telithromycin, n = 232; clarithromycin, n = 231). The mean age of the telithromycin group was 30.9 years; in the clarithromycin group, it was 30.0 years. Bacterial eradication was achieved in 91.3% of telithromycin-treated patients and 88.1% of clarithromycin recipients (difference, 3.2%; 95% CI, -4.5 to 11.0). Clinical cure was achieved in 92.7% of telithromycin recipients and 91.1% of clarithromycin-treated patients (difference, 1.6%; 95% CI, -5.5 to 8.6). Bacteriologic and clinical cures for the 2 treatment groups also were similar at the late posttherapy visit. Treatment-related adverse events occurred more frequently in the telithromycin group than the clarithromycin group (67.2% vs 57.5%, respectively); diarrhea, nausea, and vomiting were significantly more common with telithromycin than with clarithromycin (P = 0.004, 0.010, and 0.001, respectively). Adverse events were generally mild.

CONCLUSION

This study demonstrates that telithromycin 800 mg once daily for 5 days was an effective and generally well-tolerated treatment for tonsillitis/pharyngitis caused by GABHS, providing similar bacteriologic and clinical efficacy to clarithromycin 250 mg twice daily for 10 days in the per-protocol population.

A critical assessment of published guidelines and other decision-support systems for the antibiotic treatment of community-acquired respiratory tract infections

Guidelines are an important means by which professional associations and governments have sought to improve the quality and cost-effectiveness of disease management for infectious diseases. Prescribing of initial antibiotic therapy for community-acquired respiratory tract infections (RTIs) is primarily empiric and physicians may often have a limited appreciation of bacterial resistance. Recent guidelines for managing RTIs have adopted a more evidence-based approach. This process has highlighted important gaps in the existing knowledge base, e.g. concerning the impact of resistance on the effectiveness of oral antibiotics for outpatient community-acquired pneumonia and the level of resistance that should prompt a change in empiric prescribing. In upper RTIs, the challenge is to identify patients in whom antibiotic therapy is warranted. Concentrated, sustained efforts are needed to secure physicians' use of guidelines. The information should be distilled into a simple format available at the point of prescribing and supported by other behavioral change techniques (e.g. educational outreach visits). Advances in information technology offer the promise of more dynamic, computer-assisted forms of guidance. Thus, RTI prescribing guidelines and other prescribing support systems should help control bacterial resistance in the community. However, their effect on resistance patterns is largely unknown and there is an urgent need for collaborative research in this area. Rapid, cost-effective diagnostic techniques are also required and new antibiotics will continue to have a role in disease management.

Performance characteristics and utilization of rapid antigen test, DNA probe, and culture for detection of group a streptococci in an acute care clinic

Group A streptococcus (GAS) antigen testing has become a routine point-of-care (POC) test in acute care settings. Concern about performance parameters (PP) of these tests as well as inappropriate antibiotic use has resulted in various recommendations regarding diagnosis of GAS. There were two objectives in this study. The first was to evaluate the rapid GAS antigen test presently in use (Thermo BioStar, Boulder, Colo.) and the GAS Direct probe test (Gen-Probe, San Diego, Calif.) compared to culture. The second was to define the optimal use of these technologies in a large acute care pediatric clinic. A total of 520 consecutive pediatric patients presenting with symptoms of pharyngitis at any of three Lahey Clinic acute care facilities were evaluated. Pharyngeal specimens were collected using a double-swab collection device (Copan, Corona, Calif.). One swab was used for the antigen test, the second was used for the probe test, and the pledget was placed in the collection device for culture on 5% sheep blood agar, incubated for 48 h anaerobically, and subsequently placed in Todd-Hewitt broth. After discrepant analysis, sensitivity, specificity, and positive and negative predictive values were as follows: 94.8, 100, 100, and 96.9% for the probe test and 86.1, 97.1, 93.7, and 93.4% for the antigen test, respectively. Sensitivity using an enhanced culture technique was 99.4% (163 of 164). False-positive (FP) antigen results were often seen from patients previously diagnosed and/or treated for GAS. No FP results were seen with the probe test. Colony counts for the false-negative (FN) antigen tests were higher than those for the FN probe tests. Compared to culture and DNA probe, the rapid antigen test (RAT) offered a result at the time of the patient's visit, with acceptable PP when prevalence of disease is high. Follow-up testing with the RAT of GAS patients who previously tested as positive should be avoided due to increased FP results. The probe test was comparable to culture in performance. Results indicate the probe test can be used as the primary test or as a backup to negative antigen tests. The probe test offers the advantage over culture of same-day reporting of a final result but, in contrast to a POC test, necessitates follow-up communication to the patient. Preliminary data show the specificity of the probe test to be greater than that of the RAT for patients previously diagnosed with GAS.

Efficacy of short-course therapy with the ketolide telithromycin compared with 10 days of penicillin V for the treatment of pharyngitis/tonsillitis

This randomized, double-blind study compared the efficacy and safety of a 5-d course of the new ketolide antimicrobial, telithromycin, with those of a standard 10-d course of penicillin V (phenoxymethylpenicillin) in patients with group A beta-hemolytic streptococci (GABHS) pharyngitis/tonsillitis. Patients aged 15-65 y (n = 395) with clinical signs and symptoms of pharyngitis/tonsillitis and a positive streptococcal antigen test or throat culture for GABHS were randomized to receive either telithromycin 800 mg once daily for 5 d (n = 198) or penicillin V 500 mg three times daily for 10 d (n = 197). Clinical and bacteriologic outcomes were assessed at post-therapy, test-of-cure (Days 16-20) and late post-therapy (Days 38-45) visits. Telithromycin for 5 d was equivalent to 10 d of penicillin V in terms of bacteriologic and clinical outcome (per-protocol): at post-therapy, test-of-cure visit, bacteriologic outcome was satisfactory in 84.3% and 89.1% of patients in the telithromycin and penicillin V groups, respectively, while clinical cure was achieved in 94.8% and 94.1% of patients, respectively. At late post-therapy, 82.4% of patients treated with telithromycin achieved a satisfactory bacteriologic outcome, compared with 84.7% of penicillin V recipients. The GABHS eradication rates for telithromycin and penicillin post-therapy were 85.2% and 89.1%, respectively, and 86.1% and 86.5%, respectively at late post-therapy. Both treatments were well tolerated, with a similar overall incidence of treatment-emergent adverse events. Short-course (5 d) therapy with telithromycin 800 mg once daily is comparable to a standard 10 d course of penicillin V for the treatment of GABHS pharyngitis/tonsillitis in adults and adolescents.

Comparative efficacy and safety of 5-day cefaclor and 10-day amoxycillin treatment of group A streptococcal pharyngitis in children

A total of 384 children with group A beta-haemolytic streptococcal (GABHS) pharyngitis were randomized to receive either 40 mg/kg/day of cefaclor in two doses for 5 days (192 patients), or 40 mg/kg/day of amoxycillin in three doses for 10 days (192 patients). The signs and symptoms of pharyngitis were recorded and throat cultures were obtained at presentation and on days 6-7, 11-15, 16-20 and 28-35. Patient compliance was significantly higher in the children treated with cefaclor (100 vs. 95.1%; P = 0.003). At the end of follow-up, the percentage of clinical success was 91.4% for cefaclor and 91.9% for amoxycillin (P = 0.974); bacteriological success was obtained in 85.7 and 89.6% children (P = 0.348), respectively. Both treatments were well-tolerated with adverse event rates of 8.3% in the cefaclor group and 9.4% in the amoxcillin group (P = 0.857). Our study shows that five days' treatment with cefaclor is as effective and safe as the conventional 10-day course of amoxycillin in the treatment of GABHS pharyngitis, but compliance seems to be significantly greater.

Evaluating the need, timing and best choice of antibiotic therapy for acute otitis media and tonsillopharyngitis infections in children

Deciding whether an antibiotic is necessary, when to begin therapy and selecting an optimal drug is an everyday challenge in clinical practice. In vitro susceptibility testing which determines the minimum concentration necessary for a particular antibiotic to inhibit or kill most strains of a bacterial species and pharmacodynamic modeling are useful but have limitations. The need for antibiotic therapy for acute otitis media (AOM) has been recently questioned. However, explanations for uniformly positive results with many antibiotic and placebo comparative trials include overdiagnosis of AOM at study entry, inclusion of patients with mild or uncomplicated AOM and broad criteria for the definition of clinical success. Recurrent and persistent AOM does not have as favorable a natural history as uncomplicated AOM; children below 2 years of age benefit most from antibiotic therapy. Selecting the best choice among the many antibiotics that can be used to treat AOM has become more complex over the last decade due to escalating antibiotic resistance among the pathogens that cause this infection. Broader spectrum antibiotics such as cefdinir, the newly introduced third generation cephalosporin, have their most prominent use in the treatment of persistent and recurrent AOM. In the early 1950s and 1960s penicillin clearly was the best available agent for the treatment of group A streptococcal (GAS) infections. In the 1970s the situation began to change as cephalosporin antibiotics became available. Superior eradication rates with cephalosporins such as cefdinir have now been well-documented. The leading hypothesis to explain the widening gap in efficacy between penicillin and cephalosporins relates to two major concepts: the presence of copathogens and differential alteration of the normal microbial ecology in the throat as a consequence of the selected therapy. There are positive and negative consequences to early initiation of antibiotic therapy for GAS tonsillopharyngitis. Penicillin has persisting good efficacy in patients older than the age of 12 years and in those who have been ill for >2 days. Shortening therapy for GAS tonsillopharyngitis offers a therapeutic advantage. Cefpodoxime proxetil and cefdinir have a 5-day indication for the treatment of GAS tonsillopharyngitis. Antibiotics with lower side effect profile, infrequent dosing, good palatability in suspension formulation and efficacy with short duration of treatment may lead to better outcomes because noncompliance often results in failed therapy, persistence of infection and morbidity.