Background.Rapid antigen detection testing (RADT) is often performed for diagnosis of group A β-hemolytic streptococcal (GABHS) pharyngitis among children.Among adults, the sensitivity of this test varies on the basi...Background.Rapid antigen detection testing (RADT) is often performed for diagnosis of group A β-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 over-all 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 ≥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.展开更多
Background. Necrotizing fasciitis (NF) due to group A β -haemolytic strept ococci (GAS) is a rare but still life-threatening soft-tissue infection char acterized by rapidly spreading necrosis of the muscle fascia and...Background. Necrotizing fasciitis (NF) due to group A β -haemolytic strept ococci (GAS) is a rare but still life-threatening soft-tissue infection char acterized by rapidly spreading necrosis of the muscle fascia and of the surround ing tissues. NF other than that due to GAS involves the participation of one or more anaerobes and/or of non-group A streptococci, Staphylococcus aureus, ente ric organisms, and may be associated with a better outcome. Early diagnosis and treatment, consisting of surgical debridement along with appropriate antibiotic therapy, are required to reduce morbidity and mortality rates. Objectives. The a im of the study was to analyse the clinical and laboratory findings of patients with GAS NF and with non-GAS NF, and to identify which characteristics could h elp to diagnose NF in the early stages of infection. Methods. We retrospectively analysed the clinical and laboratory findings of 43 cases of GAS and non-GAS NF that occurred in Belgium (n = 32) and at Saga Medical School (Japan) (n = 11) between May 1984 and December 2001. Results. GASNF more frequently occurred in previously healthy individuals than NF due to other pathogens (P < 0.05) butwas associated with a poorer prognosis. Both for patients with GAS NF and with non- GAS NF, the first clinical manifestations often suggested a diagnosis of erysip elas or cellulitis and rarely evoked the correct diagnosis (12% and 15% of t he cases, respectively). However, we found that creatine phosphokinase (CPK) val ues were far higher in patients with GAS NF than in those with non-GAS NF. Con clusions. Our data suggest that GAS may exert particular tropism and/or toxicity for muscle, responsible for early muscle necrosis. This indicates that elevated levels of CPK in a patient with erysipelas or cellulitis-like symptoms should clearly prompt the clinician to exclude the diagnosis of GAS NF.展开更多
文摘Background.Rapid antigen detection testing (RADT) is often performed for diagnosis of group A β-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 over-all 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 ≥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.
文摘Background. Necrotizing fasciitis (NF) due to group A β -haemolytic strept ococci (GAS) is a rare but still life-threatening soft-tissue infection char acterized by rapidly spreading necrosis of the muscle fascia and of the surround ing tissues. NF other than that due to GAS involves the participation of one or more anaerobes and/or of non-group A streptococci, Staphylococcus aureus, ente ric organisms, and may be associated with a better outcome. Early diagnosis and treatment, consisting of surgical debridement along with appropriate antibiotic therapy, are required to reduce morbidity and mortality rates. Objectives. The a im of the study was to analyse the clinical and laboratory findings of patients with GAS NF and with non-GAS NF, and to identify which characteristics could h elp to diagnose NF in the early stages of infection. Methods. We retrospectively analysed the clinical and laboratory findings of 43 cases of GAS and non-GAS NF that occurred in Belgium (n = 32) and at Saga Medical School (Japan) (n = 11) between May 1984 and December 2001. Results. GASNF more frequently occurred in previously healthy individuals than NF due to other pathogens (P < 0.05) butwas associated with a poorer prognosis. Both for patients with GAS NF and with non- GAS NF, the first clinical manifestations often suggested a diagnosis of erysip elas or cellulitis and rarely evoked the correct diagnosis (12% and 15% of t he cases, respectively). However, we found that creatine phosphokinase (CPK) val ues were far higher in patients with GAS NF than in those with non-GAS NF. Con clusions. Our data suggest that GAS may exert particular tropism and/or toxicity for muscle, responsible for early muscle necrosis. This indicates that elevated levels of CPK in a patient with erysipelas or cellulitis-like symptoms should clearly prompt the clinician to exclude the diagnosis of GAS NF.
