Acute pharyngitis

Simultaneous detection of pathogens in clinical samples from patients with community-acquired pneumonia by real-time PCR with pathogen-specific molecular beacon probes

In this study, real-time PCR with pathogen-specific molecular beacons (MB) and primers was evaluated for prediction of community-acquired pneumonia (CAP) causative agents, detecting six main CAP agents, Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Streptococcus pyogenes, simultaneously. The PCR assay was evaluated for fresh clinical specimens from infants and children (n = 389) and from adults (n = 40). The MB probes and primers are both pathogen specific, namely, the lytA gene for S. pneumoniae, the mip gene for L. pneumophila, and 16S rRNA genes for the remaining four organisms. DNA extraction of clinical specimens was performed with a commercially available EXTRAGEN II kit, and amplification was performed with Stratagene Mx3000P. The limit of detection for these pathogens ranged from 2 copies to 18 copies. The whole process from DNA extraction to the analysis was finished in less than 2 h. The obtained sensitivity and specificity of this real-time PCR study relative to those of conventional cultures were as follows: 96.2% and 93.2% for S. pneumoniae, 95.8% and 95.4% for H. influenzae, 100% and 100% for S. pyogenes, and 100% and 95.4% for M. pneumoniae, respectively. The sensitivity and specificity for M. pneumoniae relative to those of a serologic assay were 90.2% and 97.9%, respectively. In six clinical samples of C. pneumoniae, the real-time PCR gave positive predictable values, and in those cases, elevation of the titer value was also observed. In conclusion, we demonstrated that a real-time PCR assay with pathogen-specific MB is useful in identifying CAP causative agents rapidly and in examining the clinical course of empirical chemotherapy in a timely manner, supporting conventional culture methods.

Population-based prevalence of repeated group A beta-hemolytic streptococcal pharyngitis episodes

OBJECTIVE

To define the population-based 3-year period prevalence of repeated group A beta-hemolytic streptococcal (GABHS) pharyngitis episodes in children between 4 and 15 years of age.

PATIENTS AND METHODS

Residents of Rochester, Minn (age, 4-15 years), who had 3 or more GABHS pharyngitis episodes In 1 year, at least 1 month apart, between January 1, 1996, and December 31, 1998, were Identified using the resources of the Rochester Epidemiology Project (N=536). Pharyngitis episodes (evidence of a sore throat with or without presence of fever) followed by either a positive rapid streptococcus test result or a positive plate culture test result were considered positive GABHS episodes. Age- and sex-specific prevalence rates were calculated, assuming that all residents 4 to 15 years of age in Rochester during 1996 to 1998 were at risk.

RESULTS

A total of 208 children met our definition for repeated GABHS episodes between 1996 and 1998 and were included in this study. Approximately 1% of children between the ages of 4 and 15 years experienced repeated GABHS pharyngitis episodes between 1996 and 1998. This estimate increased to approximately 2% among children 4 to 6 years of age and decreased to 0.1% among children 13 to 15 years old.

CONCLUSION

A relatively small proportion (1%) of children between 4 and 15 years of age experienced repeated GABHS episodes in a 3-year period; however, this proportion represents a substantial number of children who are affected at the population level. Given the increased costs associated with treating repeated GABHS episodes, further studies are necessary to determine how best to reduce episodes and treatment costs in this age group.

Acute Tonsillopharyngitis Associated with Atypical Bacterial Infection in Children: Natural History and Impact of Macrolide Therapy

This study evaluated the natural history of acute tonsillopharyngitis associated with atypical bacterial infections, showing that Mycoplasma pneumoniae and Chlamydia pneumoniae organisms are frequently found in children with acute tonsillopharyngitis. The study also demonstrated, for what we believe to be the first time, that, unless adequately treated, acute tonsillopharyngitis associated with infection with M. pneumoniae and C. pneumoniae may have a negative outcome with a high risk of recurrence of respiratory illness.

Optimal site for throat culture: tonsillar surface versus posterior pharyngeal wall

To determine the optimal site of throat culture for the detection of potential pathogens by comparing culture results from the tonsillar surface and the posterior pharyngeal wall in children selected for adenotonsillectomy and in children without upper respiratory disease. Cotton culture swabs were taken from the tonsillar surface and the posterior pharyngeal wall of 50 children selected for adenotonsillectomy for symptoms of recurrent tonsillitis and/or adenotonsillar hypertrophy and of 50 children without upper respiratory disease. Potential respiratory pathogens were identified. In the overall group (n = 100), positive culture results were found in 67 posterior pharyngeal wall samples and 47 tonsillar surface samples (P = 0.001). Haemophilus influenzae was the most frequently isolated micro-organism both in the posterior pharyngeal wall and the tonsillar surface samples; 55 and 35%, respectively (P = 0.001). Group A beta-haemolytic streptococci were found in the samples of the posterior pharyngeal wall and the tonsillar surface in 17 and 13%, respectively (P = 0.2). When dealing with patients with sore throat, sampling both tonsillar surfaces is enough for the detection of group A beta-haemolytic streptococci. When detection of other bacteria is also important, such as for research purposes, the posterior pharyngeal wall should be sampled as well.

IdeS, a highly specific immunoglobulin G (IgG)-cleaving enzyme from Streptococcus pyogenes, is inhibited by specific IgG antibodies generated during infection

IdeS, a recently discovered cysteine proteinase secreted by the important human pathogen Streptococcus pyogenes, interferes with phagocytic killing by specifically cleaving the heavy chain of immunoglobulin G. The fact that the enzyme targets one of the key molecules of the adapted immune response raised the question of whether an antibody response against IdeS could inhibit, i.e., neutralize, enzyme activity. Paired acute- and convalescent-phase serum samples from patients with pharyngotonsillitis (n = 10), bacteremia (n = 7), and erysipelas (n = 4) were analyzed. Antibodies with the ability to neutralize IdeS enzymatic activity were already found in two-thirds of acute-phase sera. However, patients who seroconverted to IdeS, in particular patients with pharyngotonsillitis and erysipelas, developed specific antibodies during convalescence with an increased capability to efficiently neutralize the enzymatic activity of IdeS. Also, the presence of neutralizing antibodies decreased the ability of IdeS to mediate bacterial survival in human immune blood. In patients with bacteremia, several acute-phase sera contained neutralizing antibodies, but no correlation was found to severity or outcome of invasive infections. Still, the fact that the human immune response targets the enzymatic activity of IdeS supports the view that the enzyme plays an important role during streptococcal infection.

Advances in potential M-protein peptide-based vaccines for preventing rheumatic fever and rheumatic heart disease

Rheumatic fever (RF) and rheumatic heart disease (RHD) are postinfectious complications of an infection (or repeated infection) with the Gram-positive bacterium, Streptococcus pyogenes (also known as group A streptococcus, GAS). RF and RHD are global problems and affect many indigenous populations of developed countries and many developing countries. However, RF and RHD are only part of a larger spectrum of diseases caused by this organism. The development of a vaccine against GAS has primarily targeted the abundant cell-surface protein called the M-protein. This review focuses on different M-protein-based-subunit vaccine approaches and the different delivery technologies used to administer these vaccine candidates in preclinical studies.

Role of rapid antigen detection test for the diagnosis of group-A ß-hemolytic streptococcus in patients with pharyngotonsillitis

Group A ß-hemolytic streptococcus (GAS) is an important pharyngotonsillitis etiologic agent. Correct etiologic diagnosis and early treatment prevent suppurative and non-suppurative complications of streptococcal pharyngotonsillitis, however, clinical diagnostic methods are not reliable. Within this context, rapid detection methods of GAS antigen are useful to diagnose this agent.

Aim

The objective of the present study was to determine the sensitivity and specificity of rapid GAS antigen detection tests used in Brazil.

Study Design

Clinical prospective.

Methods

Eighty-one patients with clinical diagnosis of acute pharyngotonsillitis seen at the otorhinolaryngology emergency department of University Hospital, FMUSP, between May 2001 and April 2002, were submitted to two simultaneous collections of oropharyngeal material using swabs. Rapid GAS antigen detection test was compared to culture on blood agar, the gold standard for the diagnosis of this etiologic agent.

Results

Among the 81 studied patients, the rapid test was positive in 56% and negative in 44%. GAS growth in culture was observed for 40.7% of the patients. The sensitivity and specificity of the rapid test were, respectively, 93.9% and 68.7%, and the negative and positive predictive values were 94.2 and 67.4%, respectively.

Conclusions

We concluded that the high sensitivity of the test permits its use for the identification of patients with GAS. Rapid streptococcal antigen detection tests have been shown to be an important supporting tool in the etiologic diagnosis of pharyngotonsillitis.

Prospects for a group A streptococcal vaccine: rationale, feasibility, and obstacles--report of a National Institute of Allergy and Infectious Diseases workshop

Infections due to group A streptococci (GAS) represent a public health problem of major proportions in both developing and developed countries. Currently available methods of prevention are either inadequate or ineffective, as attested to by the morbidity and mortality associated with this ubiquitous pathogen worldwide. Advances in molecular biology have shed new light on the pathogenesis of GAS infections and have identified a number of virulence factors as potential vaccine targets. Therefore, the National Institute of Allergy and Infectious Diseases convened an expert workshop in March 2004 to review the available data and to explore the microbiologic, immunologic, epidemiologic, and economic issues involved in development and implementation of a safe and effective GAS vaccine. Participants included scientists and clinicians involved in GAS research, as well as representatives of United States federal agencies (Centers for Disease Control and Prevention, Food and Drug Administration, Department of Defense, and National Institute of Allergy and Infectious Diseases), the World Health Organization, and the pharmaceutical industry. This report summarizes the deliberations of the workshop.

HIV in adolescents

Adolescence is a time of dramatic physical, emotional, cognitive, and social change that brings new vulnerabilities. Youth represent half of all new HIV infections in the United States and the rest of the world. The number of newly infected adolescents who acquire the disease behaviorally and the number of perinatally infected children surviving into adolescence have both contributed to this growth. This article reviews the most recent epidemiology of HIV/AIDS in adolescents, gives guidance on clinical practice, including medical and psychosocial care, and examines prevention issues, including counseling and testing, which are needed to make programs effective for youth.

Growth characteristics of and virulence factor production by group A Streptococcus during cultivation in human saliva

Group A Streptococcus (GAS) commonly infects the human oropharynx, but the initial molecular events governing this process are poorly understood. Saliva is a major component of the innate and acquired immune defense in this anatomic site. Although landmark studies were done more than 60 years ago, investigation of GAS-saliva interaction has not been addressed extensively in recent years. Serotype M1 GAS strain MGAS5005 cultured in human saliva grew to approximately 10(7) CFU/ml and, remarkably, maintained this density for up to 28 days. Strains of several other M-protein serotypes had similar initial growth patterns but did not maintain as high a CFU count during prolonged culture. As revealed by analysis of the growth of isogenic mutant strains, the ability of GAS to maintain high numbers of CFU/ml during the prolonged stationary phase in saliva was dependent on production of streptococcal inhibitor of complement (Sic) and streptococcal pyrogenic exotoxin B (SpeB). During cultivation in human saliva, GAS had growth-phase-dependent production of multiple proven and putative extracellular virulence factors, including Sic, SpeB, streptococcal pyrogenic exotoxin A, Mac protein, and streptococcal phospholipase A(2). Our results clearly show that GAS responds in a complex fashion to growth in human saliva, suggesting that the molecular processes that enhance colonization and survival in the upper respiratory tract of humans are well under way before the organism reaches the epithelial cell surface.

Role of rapid antigen detection test for the diagnosis of group A beta-hemolytic streptococcus in patients with pharyngotonsillitis

Group A β -hemolytic streptococcus (GAS) is an important pharyngotonsillitis etiologic agent. Correct etiologic diagnosis and early treatment prevent suppurative and non-suppurative complications of streptococcal pharyngotonsillitis; however, clinical diagnosis is not reliable. Within this context, rapid detection methods of GAS antigen are useful to diagnose this agent.

Aim

The objective of the present study was to determine sensitivity and specificity of rapid GAS antigen detection tests used in Brazil.

Study design

Clinical prospective. Method: Eighty-one patients with clinical diagnosis of acute pharyngotonsillitis seen at the otorhinolaryngology emergency department of the University Hospital, FMUSP, between May 2001 and April 2002 were submitted to two simultaneous collections of oropharyngeal material using swabs. The rapid GAS antigen detection test was compared to culture on blood agar, the gold standard for the diagnosis of this etiologic agent.

Results

Among the 81 patients studied, the rapid test was positive in 56% and negative in 44%. GAS growth in culture was observed in 40.7% of the patients. Sensitivity and specificity of the rapid test were, respectively, 93.9% and 68.7%, and the negative and positive predictive values were 94.2 and 67.4%, respectively. Conclusions: We concluded that high sensitivity of the test allows its use in the identification of patients with GAS. Rapid streptococcal antigen detection tests have been shown to be an important adjuvant tool in the etiologic diagnosis of pharyngotonsillitis.

The role of point of care testing for patients with acute pharyngitis

BACKGROUND

There is no consensus favoring a particular strategy for evaluating patients with pharyngitis.

OBJECTIVE

To compare a clinical decision aid and a rapid office-based point of care (POC) test with routine culture for group A beta-hemolytic streptococcus (GAS).

DESIGN

Prospective observational study.

PARTICIPANTS

Among 179 patients enrolled, 150 were eligible and 148 had POC testing and cultures initially performed.

MEASUREMENTS

An encounter form included eligibility criteria, clinical information based upon the Centor rule, and treatment provided. Sensitivity and specificity of POC test compared to routine culture for GAS.

RESULTS

Thirty-eight patients (25.7%) had a positive GAS culture. The POC test was 92.1% sensitive (95% confidence interval [CI] 80% to 98%) and 100% specific (95% CI 97% to 100%). Although the Centor rule did not adequately discriminate among symptomatic patients with or without GAS (receiver operating curve area 0.63), the 3 patients with a false-negative POC test had a Centor score of less than 2. Among patients with a negative POC test, 26% initially received antibiotics.

CONCLUSIONS

For patients with a Centor score of > or =2, a POC test was highly sensitive for GAS. Future studies should confirm these results and assess whether implementation of POC testing as part of a local practice guideline can decrease variability in testing and treatment.

Antimicrobial susceptibilities of potential bacterial pathogens in adults with acute respiratory tract infections Prospective Epidemiological Network Investigating Community-acquired Infection SurveiLLance In Nagasaki (PENICILLIN) Study

The prevalence and the antimicrobial susceptibilities of bacterial pathogens in acute upper respiratory tract infections (AURTIs) is not clear. We conducted a prospective community-based multicenter study in 45 centers across Nagasaki, Japan, between December 2001 and April 2002. We examined the nasopharyngeal or throat isolates in 930 adult outpatients with AURTIs. Potential bacterial pathogens, including Streptococcus pyogenes (from 6.8% patients), S. pneumoniae (5.3%), S. milleri group (2.0%), Staphylococcus aureus (26.0%), Moraxella catarrhalis (7.4%), Haemophilus influenzae (17.6%), and Klebsiella pneumoniae (1.2%), were isolated from 51.8% of the patients. Penicillin nonsusceptible phenotype accounted for 44.9% of S. pneumoniae isolates. Among Staphylococcus aureus isolates, 9.1% were methicillin-resistant. In H. influenzae isolates, 6.7% produced beta-lactamase and 23.2% were beta-lactamase-negative ampicillin-resistant. The results indicated that the potential bacterial pathogens were detected in the remarkable population of the adults with AURTIs and the current antimicrobial susceptibilities of such pathogens.

Training room management of medical conditions: infectious diseases

Management of infectious diseases in athletes encompasses a wide range of pathogens, clinical presentations, and treatment options. Certain athletic activities and training regimens may predispose athletes to increased risk of contracting infectious diseases, some of which may limit athletic participation and pose the threat of significant morbidity. The sports medicine physician plays an important role as a first line of defense in preventing, recognizing, and appropriately treating infectious diseases in athletes.

Papel do teste de detecção rápida do antígeno do estreptococcus pyogenes do grupo a em pacientes com faringoamigdalites

O Streptococcus pyogenes do grupo A (SGA) é o agente etiológico mais comum das faringoamigdalites (FA). O diagnóstico etiológico correto e tratamento adequado evitam complicações supurativas e não-supurativas da faringoamigdalite estreptocócica, entretanto, métodos clínicos de diagnóstico não são confiáveis. Os métodos rápidos de detecção do antígeno do SGA podem ser utilizados no diagnóstico deste agente e evitar uso indevido de antibióticos. OBJETIVOS: Os autores objetivaram avaliar a sensibilidade e especificidade dos testes rápidos para detecção do antígeno do SGA em nosso meio. FORMA DE ESTUDO: Clínico prospectivo. CASUÍSTICA E MÉTODO: Oitenta e um pacientes com faringoamigdalite aguda, atendidos no PS-ORL do Hospital das Clínicas da FMUSP, no período de maio de 2001 a abril de 2002, foram submetidos a duas coletas simultâneas de material de orofaringe com swabs. O teste rápido de detecção do SGA foi confrontado com a cultura em placa agar-sangue ("gold standard" para o diagnóstico etiológico). RESULTADOS: De 81 pacientes, 56% tiveram teste rápido positivo e 44% negativo; 40.7% apresentaram crescimento de SGA na cultura; a sensibilidade e especificidade do teste rápido foram, respectivamente, 93,9% e 68,7%. O valor preditivo negativo e positivo foram, respectivamente, 94,2% e 67,4%. COMENTÁRIOS FINAIS: A alta sensibilidade do exame permite utilizá-lo com intuito de identificar pacientes com SGA. Os testes de detecção rápida do antígeno estreptocócico se mostraram uma importante arma coadjuvante no diagnóstico etiológico das faringoamigdalites.

Real-time PCR investigation into the importance of Fusobacterium necrophorum as a cause of acute pharyngitis in general practice

Fusobacterium necrophorum is recognized as the cause of a severe life-threatening illness characterized by bacteraemia with metastatic abscesses following an acute sore throat (Lemierre's disease). However, the importance of F. necrophorum as a cause of simple sore throat in the community is unknown. Using quantitative real-time PCR with primers targeting the rpoB gene, 100 routine throat swabs collected from patients presenting to general practitioners with pharyngitis were analysed for the presence of F. necrophorum-specific DNA. The results were compared with those obtained from throat swabs collected from 100 healthy subjects. Ten clinical samples were positive for F. necrophorum DNA, identified as F. necrophorum subspecies funduliforme, using a haemagglutinin-related protein gene-specific PCR assay. All the healthy controls were negative (two-tailed P value = 0.0015; Fisher exact test). These findings suggest that F. necrophorum may play a more important role as a cause of simple sore throat in the community than has been previously appreciated.

Two dosages of clarithromycin for five days, amoxicillin/clavulanate for five days or penicillin V for ten days in acute group A streptococcal tonsillopharyngitis

BACKGROUND

Short course antimicrobial therapy is suggested for group A streptococcal tonsillopharyngitis.

METHODS

The bacteriologic and clinical efficacies of clarithromycin [30 or 15 mg/kg/day twice daily (b.i.d.)] or amoxicillin/clavulanate (43.8/6.2 mg/kg/day b.i.d.) for 5 days or penicillin V (30 mg/kg/day 3 times a day) for 10 days were compared. In a randomized, open label, parallel group, multicenter study, 626 children (2-16 years old) with tonsillopharyngitis were enrolled; 537 were evaluable for efficacy. Follow-up evaluations were performed at 4-8 and 21-28 days after therapy.

RESULTS

At enrollment, 26% of the Streptococcus pyogenes isolates were clarithromycin-nonsusceptible. All regimens had an apparently similar clinical efficacy. The long term S. pyogenes eradication rates were 102 of 123 (83%) with amoxicillin/clavulanate and 88 of 114 (77%) with penicillin V. In the 30- and 15-mg/kg/day clarithromycin groups, eradication occurred in 71 of 86 (83%) and 59 of 80 (74%) of the clarithromycin-susceptible isolates (P = 0.33), and in 4 of 28 (14%) and 5 of 26 (19%) of the clarithromycin-resistant isolates, respectively (clarithromycin-susceptible versus -resistant, P < 0.0001). Both clarithromycin dosages were well-tolerated.

CONCLUSIONS

In group A streptococcal tonsillopharyngitis, 5 days of clarithromycin or amoxicillin/clavulanate treatment had clinical efficacy comparable with that of 10 days of penicillin V treatment; however, amoxicillin/clavulanate and penicillin V were bacteriologically more effective than clarithromycin because of its failure to eradicate the clarithromycin-resistant S. pyogenes isolates. The 5-day clarithromycin regimens are not recommended for treatment of streptococcal tonsillopharyngitis in areas where in vitro resistance of group A streptococci to clarithromycin is common.

Aetiology of acute pharyngitis: the role of atypical bacteria

In order to establish the role of atypical bacteria and compare characteristics of different infectious agents in acute pharyngitis, 127 patients with acute pharyngitis (66 males; median age, 5.33 years; range, 6 months to 14 years) and 130 healthy subjects of similar sex and age were studied. Serology with paired samples and PCR on nasopharyngeal aspirates and throat cultures were used to identify bacteria and viruses. Viruses were identified in 43 patients (33.8%) and five controls (3.8%; P < 0.0001), potential bacterial pathogens in 34 patients (26.8%) and 26 controls (20%; P = 0.256) and mixed viral/bacterial pathogens in 26 patients (20.5%) and none of the controls (P < 0.0001). The main aetiological agents were adenovirus, respiratory syncytial virus (RSV), Mycoplasma pneumoniae, Streptococcus pyogenes and Chlamydia pneumoniae. M. pneumoniae was the agent found most frequently as a single pathogen. A history of recurrent pharyngitis, having older siblings and a negative outcome were significantly more common among patients with acute M. pneumoniae infection than among those with infections due to other pathogens or healthy controls. This study demonstrates that: (i) adenovirus and RSV have a prominent role in acute pharyngitis; (ii) S. pyogenes is found frequently, but it is not possible to distinguish simple carriers from patients with a true infection; (iii) M. pneumoniae appears to be able to cause acute pharyngitis per se; and (iv) C. pneumoniae seems to be mainly a co-pathogen. To avoid the risk of an incorrect therapeutic approach, simple laboratory investigations that allow rapid identification of M. pneumoniae infections are urgently needed.

Spectrum bias of a rapid antigen detection test for group A beta-hemolytic streptococcal pharyngitis in a pediatric population

BACKGROUND

Rapid antigen detection testing (RADT) is often performed for diagnosis of group A beta-hemolytic streptococcal (GABHS) pharyngitis among children. Among adults, the sensitivity of this test varies on the basis of disease severity (spectrum bias). A similar phenomenon may occur when this test is used in a pediatric population, which may affect the need for culture confirmation of all negative RADT results.

OBJECTIVES

To assess the performance of a clinical scoring system and to determine whether RADT spectrum bias is present among children who are evaluated for GABHS pharyngitis.

METHODS

Laboratory and clinical records for a consecutive series of pediatric patients who underwent RADT at the Marshfield Clinic between January 2002 and March 2002 were reviewed retrospectively. Patients were stratified according to the number of clinical features present by using modified Centor criteria, ie, history of fever, absence of cough, presence of pharyngeal exudates, and cervical lymphadenopathy. The sensitivity of the RADT was defined as the number of patients with positive RADT results divided by the number of patients with either positive RADT results or negative RADT results but positive throat culture results.

RESULTS

RADT results were positive for 117 of 561 children (21%), and culture results were positive for 35 of 444 children (8%) with negative RADT results. The overall prevalence of GABHS pharyngitis was 27% (95% confidence interval: 23-31%). The prevalence of GABHS pharyngitis was 18% among patients with 0 Centor criteria, 16% among those with 1 criterion, 32% among those with 2 criteria, and 50% among those with 3 or 4 criteria. Spectrum bias was present, inasmuch as RADT sensitivity increased with Centor scores, ie, 47% sensitivity among children with 0 Centor criteria, 65% among those with 1 criterion, 82% among those with 2 criteria, and 90% among those with 3 or 4 criteria.

CONCLUSIONS

The sensitivity of RADT for GABHS pharyngitis is not a fixed value but varies with the severity of disease. However, even among pediatric patients with > or =3 Centor criteria for GABHS pharyngitis, the sensitivity of RADT is still too low to support the use of RADT without culture confirmation of negative results.

Pharyngitis clinical prediction rules: effect of interobserver agreement: a MetroNet study

OBJECTIVE

Pharyngitis clinical prediction rules improve Group A beta-hemolytic streptococcus (GABHS) diagnosis and decrease unnecessary antibiotic use, yet few studies have addressed clinician variability in assessment of sore throat signs and symptoms.

STUDY DESIGN AND SETTING

We conducted a cross-sectional study in which two clinicians examined each of 200 adult sore throat patients. Each patient had a rapid GABHS antigen test. Clinicians were blinded to each other's assessment and to the rapid antigen result. Interobserver agreement was estimated using a kappa coefficient. Effect of agreement on sensitivity, specificity, and hypothetic rapid antigen testing and antibiotic prescribing was determined for two clinical prediction rules.

RESULTS

We found moderate inter-rater reliability on sore throat history and physical assessments. Clinician agreement was associated with significantly fewer hypothetic rapid antigen tests performed.

CONCLUSION

Interobserver agreement enhances the utility of pharyngitis clinical prediction rules. Medical school and residency training should focus on correct assessment of history and physical examination components used in GABHS clinical prediction rules. Correct assessment will result in less GABHS testing and antibiotic prescriptions for sore throat patients.

Rapid Detection and Diagnosis of Group A Streptococcal Pharyngitis

This article reviews techniques of rapid testing and the effective diagnosis of streptococcal pharyngitis. Despite 50 years' study of streptococcal pharyngitis and 20 years' experience with rapid tests for its diagnosis, the subject continues to evolve. Rapid diagnostic tests have become more sensitive. Experts now consider not if but when they may replace throat cultures. Highly accurate rapid tests will still challenge clinicians to screen the right patients. The improvement of clinical diagnosis will require an understanding of the clinical spectrum of pharyngitis and questions relating to disease prevalence, test performance, and medical decision making. Implications for diagnostic strategies are discussed.

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.

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.

Association between antibiotic prescribing and visit duration in adults with upper respiratory tract infections

BACKGROUND

Upper respiratory tract infections (URTIs) are the most common reason for individuals to seek health care in the United States. Inappropriate antibiotic use exposes patients unnecessarily to potential adverse events and increases the prevalence of antibiotic-resistant bacteria. One of the reasons physicians may prescribe an antibiotic inappropriately is to save time.

OBJECTIVE

The aim of this study was to determine whether there is an association between antibiotic use and a shorter visit duration in adults with URTIs.

METHODS

Visits to office-based primary care physicians made by adults aged 18 to 60 years from 1995 through 2000 were extracted from the National Ambulatory Medical Care Survey. Visits that resulted in a primary diagnosis of acute URTI; acute nasopharyngitis; acute bronchitis; sinusitis; streptococcal sore throat, acute pharyngitis, or acute tonsillitis; or otitis media were included in the study. Visits associated with >1 diagnosis were included in a separate category Visit duration was defined as the face-to-face time between the patient and physician.

RESULTS

There were 3764 visits that met the criteria for inclusion in this study, representing an estimated 27 million annual visits to office-based primary care physicians by adults with URTIs. Antibiotics were prescribed in 67% of visits. The mean visit duration associated with prescription of an antibiotic was 14.2 minutes, compared with 15.2 minutes without prescription of an antibiotic (P = 0.007). In multivariable modeling, independent predictors of visit duration were calendar year (additional 0.3 minute per year; 95% CI, 0.1 to 0.6), internal medicine specialty (additional 2.2 minutes vs family practice; 95% CI, 1.3 to 3.1), covisit with a nurse-practitioner or physician assistant (6.6 minutes shorter; 95% CI, -2.7 to -10.6), and Midwestern location of practice (1.1 minutes shorter vs Northeast; 95% CI, -0.1 to -2.2). Antibiotic use was marginally associated with a shorter visit duration (0.7 minute shorter; 95% CI, 0.0 to -1.3; P = NS).

CONCLUSIONS

In the present study, antibiotic use was marginally associated with a shorter visit duration for adults with URTIs. Any potential efficiencies gained by physicians through prescribing antibiotics for adults with URTIs are likely to be outweighed by increases in antimicrobial resistance and exposure of patients to unneeded medication.

Daily reduction in C-reactive protein values, symptoms, signs and temperature in group-A streptococcal pharyngitis treated with antibiotics

C-reactive protein (CRP) value is usually elevated in patients with group A streptococcal (GAS) pharyngitis. The aim of this study was to describe the daily changes in CRP value after start of antibiotic treatment and to compare these changes with commonly used outcome measures in GAS pharyngitis. Eleven adult patients with sore throat and confirmed GAS infection were examined daily by specially trained medical students who registered symptoms and signs, performed a CRP test (NycoCard) and measured body temperature. At baseline, the mean CRP value was 100.3 mg/L (SD 80.9). The mean reduction after one day was 34.1% (SD 15.3), after two days 60.1% (SD 14.1) and after three days 75.3% (SD 12.5). Corresponding reductions were found for sign and symptom scores and temperature, but the standard deviations for these measures were much larger. The CRP value was significantly associated with both the symptom score and the number of days after start of treatment (p < 0.01), but not with the sign score and body temperature, as shown by multiple regression analysis for repeated measurements. The CRP test seems to be a valid test for monitoring the clinical course in GAS pharyngitis.

[Reliability and general practice value of 2 rapid Streptococcus A tests]

Rapid streptococcal-A-antigen detection assays have good specificity (over 90 percent) but moderate sensitivity (between 80 and 90 percent), when the tests are compared with a standard throat culture. Contradictory results have been found for one of the more recent tests, the optical immune assay Strep A OIA MAX, while for 6 years, we have been using the immune assay Strep A Plus. Results of the optical immunoassay and the conventional immune assay Strep A Plus were compared in 65 patients with acute pharyngitis. A standard culture was used as reference and confirmed by enhanced broth culturing and nucleic acid hybridization assay (Gen-Probe) when the two detection assays produced contradictory results. While both assays were equally sensitive (78.3%), Strep A OIA MAX and Strep A Plus had a similar specificity of 95.2% and 100%, respectively. Four and nine steps were required for Strep A Plus and for Strep A OIA MAX test procedures, respectively with results being available in 4-5 min and in 9-10 min, respectively. We conclude that both rapid immunoassays have a similar reliability while the handling of the Strep A Plus is much simpler than the handling of the Strep A OIA MAX. Neither rapid immunoassays are sensitive enough to eliminate the need for backup cultures.

Group A Streptococcus gene expression in humans and cynomolgus macaques with acute pharyngitis

The molecular mechanisms used by group A Streptococcus (GAS) to survive on the host mucosal surface and cause acute pharyngitis are poorly understood. To provide new information about GAS host-pathogen interactions, we used real-time reverse transcription-PCR (RT-PCR) to analyze transcripts of 17 GAS genes in throat swab specimens taken from 18 pediatric patients with pharyngitis. The expression of known and putative virulence genes and regulatory genes (including genes in seven two-component regulatory systems) was studied. Several known and previously uncharacterized GAS virulence gene regulators were highly expressed compared to the constitutively expressed control gene proS. To examine in vivo gene transcription in a controlled setting, three cynomolgus macaques were infected with strain MGAS5005, an organism that is genetically representative of most serotype M1 strains recovered from pharyngitis and invasive disease episodes in North America and Western Europe. These three animals developed clinical signs and symptoms of GAS pharyngitis and seroconverted to several GAS extracellular proteins. Real-time RT-PCR analysis of throat swab material collected at intervals throughout a 12-day infection protocol indicated that expression profiles of a subset of GAS genes accurately reflected the profiles observed in the human pediatric patients. The results of our study demonstrate that analysis of in vivo GAS gene expression is feasible in throat swab specimens obtained from infected human and nonhuman primates. In addition, we conclude that the cynomolgus macaque is a useful nonhuman primate model for the study of molecular events contributing to acute pharyngitis caused by GAS.

Comparison of LightCycler PCR, rapid antigen immunoassay, and culture for detection of group A streptococci from throat swabs

We compared the performance characteristics of a real-time PCR method, the LightCycler Strep-A assay (Roche Applied Science, Indianapolis, Ind.), to those of a rapid antigen immunoassay, the Directigen 1-2-3 Group A Strep Test kit (BD Diagnostic Systems, Sparks, Md.), and a standard culture method for detection of group A streptococci (GAS) from 384 throat swabs. The LightCycler PCR produced more positive results (n = 58) than either culture (n = 55) or the Directigen immunoassay (n = 31). The results of the LightCycler PCR and the Directigen method were independently compared to the results of the accepted "gold standard," bacterial culture. The sensitivities, specificities, and positive and negative predictive values for this comparison were as follows: for the Directigen method, 55, 99, 97, and 93%, respectively; for the LightCycler PCR, 93, 98, 88, and 99%, respectively. In no case was a throat swab positive by both the LightCycler PCR and the Directigen method but negative by culture. The medical histories of patients whose throat swabs were negative by culture but positive by either the LightCycler PCR (n = 7) or the Directigen method (n = 1) were reviewed. All of these patients had signs or symptoms compatible with GAS disease, and therefore, all of these discordant positive results (along with positive results by either the Directigen method or the LightCycler PCR that agreed with the culture results) were counted as true positives for statistical analysis. For this analysis, the LightCycler PCR detected more true-positive results than the culture method (58 versus 55 swabs); however, this difference was not statistically significant (P = 0.5465). In contrast, statistically significantly more true-positive results occurred by culture than by the Directigen method (55 versus 31 swabs; P < 0.0001) and by the LightCycler PCR than by the Directigen method (58 versus 31 swabs; P < 0.0001). The LightCycler PCR is a suitable stand-alone method for the detection of GAS from throat swabs. Additionally, this method requires less than half the personnel time and the procedure can be completed in considerably less time ( approximately 1 h) than our standard approach (up to 2 days) for detection of GAS in throat swabs (i.e., testing by the Directigen method with negative results verified by culture).

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.

Treatment of sore throat in light of the Cochrane verdict: is the jury still out?

There are few good-quality studies of the effectiveness of antibiotic treatment of proven group A streptococcal (GAS) pharyngitis in children; available data suggest that antibiotics may reduce symptom duration. While there is limited justification for antibiotic treatment of GAS pharyngitis to prevent acute rheumatic fever in non-Indigenous Australians, there is no justification for routine antibiotic treatment of all patients with sore throat. Two strategies are open to clinicians: not to treat GAS pharyngitis with antibiotics, in which case no investigations should be done; or to treat cases of sore throat with clinical features that suggest GAS, in which case diagnosis should be confirmed with a throat swab, and penicillin started while awaiting the result. Penicillin should be discontinued if the swab is negative, or continued for 10 days if it is positive for GAS. Surveillance of GAS infections and acute rheumatic fever is needed in Australia, as are further studies of effectiveness (including cost-effectiveness) of antibiotic treatment of proven GAS pharyngitis.

Diagnosis of strep throat in adults: are clinical criteria really good enough?

The clinical manifestations of group A streptococcal and nonstreptococcal pharyngitis overlap quite broadly. For this reason, the updated Infectious Diseases Society of America practice guideline for group A streptococcal pharyngitis, published in this issue of Clinical Infectious Diseases, recommends laboratory confirmation of the clinical diagnosis by means of either throat culture or a rapid antigen detection test. However, a recently published guideline, developed by a subcommittee of the American College of Physicians-American Society of Internal Medicine (ACP-ASIM) in collaboration with the Centers for Disease Control and Prevention, advocates use of a clinical algorithm alone, in lieu of microbiologic testing, for confirmation of the diagnosis in adults for whom the suspicion of streptococcal infection is high. In this discussion, we examine the assumptions of the ACP-ASIM guideline, question whether its recommendations will achieve the stated objective of dramatically decreasing excess antibiotic use, and suggest that its recommendations be confirmed by clinical trials before clinicians abandon long-held teachings regarding diagnosis and management of group A streptococcal pharyngitis.

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.

Do proficiency testing participants learn from their mistakes? Experience from the EXCEL throat culture module

CONTEXT

Participation in proficiency testing is required under the Clinical Laboratory Improvement Amendments of 1988. Although the primary purpose of this testing is evaluation of current laboratory performance, a major secondary benefit of such testing is postulated to be progressive improvement in laboratory performance over time as laboratories learn from their previous experiences and feedback.

OBJECTIVE

To test the hypothesis that a secondary result of proficiency testing is improvement over time of laboratory performance.

DESIGN

The performance of participants in a large proficiency testing program (EXCEL), designed for clinic and office laboratories, on a specific problematic competence, the ability to differentiate group A streptococcus from group C streptococci, was monitored during a 6-year period (1996-2001) for changes in participant performance.

INTERVENTIONS

With each testing cycle, feedback on performance relative to peers and an educational discussion analyzing performance and suggesting best practices was submitted to participants.

RESULTS

Despite consistent feedback, there was no significant change in participant performance throughout the period studied.

CONCLUSIONS

In a large, stable proficiency testing program, a significant throat culture competence, which demonstrated less than optimal performance, did not improve over time, suggesting that current utilization of proficiency testing results in laboratory improvement programs is suboptimal.

Antimicrobial susceptibilities of Streptococcus pyogenes isolated from respiratory and skin and soft tissue infections: United States LIBRA surveillance data from 1999

This study evaluated current levels of antimicrobial resistance and associated demographic trends among clinical isolates of Streptococcus pyogenes in the United States as part of the LIBRA surveillance initiative. In 1999, 2,742 isolates of S. pyogenes (2,039 respiratory; 405 skin and soft tissue; 148 blood) were collected from 324 clinical laboratories and centrally tested for antimicrobial susceptibility by the broth microdilution method. All isolates were susceptible to penicillin (MIC(90,) < or = 0.06 microg/mL), ceftriaxone (MIC(90,) < or =0.03 microg/mL), vancomycin (MIC(90,) 0.5 microg/mL), levofloxacin (MIC(90,) 1 microg/mL), and moxifloxacin (MIC(90,) 0.25 microg/mL). Twenty-four (0.9%) azithromycin-intermediate (MIC, 1 microg/mL) and 170 (6.2%) azithromycin-resistant (MIC, > or = 2 microg/mL) isolates were identified. Regionally, azithromycin resistance varied by < 5%, ranging from 3.0% in New England to 7.7% in the Pacific region. Azithromycin resistance was significantly higher (P < 0.001) among patients aged 15-64 years (8.3%) than patients < or =14 years (4.3%). This study found higher rates of macrolide resistance among S. pyogenes than previously reported in the United States and suggests that macrolide resistance is common among respiratory isolates from both younger and older patients. Fluoroquinolones (moxifloxacin > levofloxacin) demonstrated potent in vitro activity against all isolates of S. pyogenes tested, including those from skin and soft tissue infections. Given the higher rates of macrolide resistance reported in other countries and the seriousness of invasive infections, continued antimicrobial surveillance of S. pyogenes in the United States would be prudent.

Rheumatic fever in the 21st century

In the first half of the twentieth century, the group A streptococcus (GAS) was established as the sole etiologic agent of acute rheumatic fever (ARF). In the century's latter half, the clinical importance of variation in the virulence of strains of GAS has become clearer. Although still obscure, the pathogenesis of ARF requires primary infection of the throat by highly virulent GAS strains. These contain very large hyaluronate capsules and M protein molecules. The latter contain epitopes that are cross-reactive with host tissues and also contain superantigenic toxic moieties. In settings where ARF has become rare, GAS pharyngitis continues to be common, although it is caused by GAS strains of relatively lower virulence. These strains, however, colonize the throat avidly and stubbornly. Molecularly distinct pyoderma strains may cause acute glomerulonephritis, but they are not rheumatogenic, even though they may secondarily colonize and infect the throat. Guidelines for the diagnosis, treatment, and prevention of GAS pharyngitis and ARF are reviewed with particular reference to the prevalence of the latter in the community.