Obtaining a throat culture

Improving the prediction of streptococcal pharyngitis; time to move past exudate alone

BACKGROUND

Palatal petechiae are predictive of Group A streptococcal (GAS) pharyngitis. We sought to (a) quantify the value of considering petechiae in addition to exudate, and (b) assess provider incorporation of petechiae's predictive nature for GAS into clinical decision making.

METHODS

We conducted a cross-sectional study of patients 3-21 years with sore throat and GAS testing performed in a pediatric emergency department (ED) in 2016. Patients were excluded if immunosuppressed, nonverbal, medically complex, had chronic tonsillitis, or received antibiotics in the preceding week. As a proxy of provider incorporation of petechiae into clinical decision making we assessed how often petechiae were documented, compared with exudate. We performed univariate analysis using χ² analysis for categorical data and Mann-Whitney U test for continuous data.

RESULTS

1574 patients met inclusion criteria. Median age 8 years [IQR 5, 13]; 54% female. 372 patients (24%) were GAS positive. Both palatal petechiae and tonsillar exudates were predictive of GAS [OR 8.5 (95% CI 5.2-13.9), and 1.9 (95% CI 1.4-2.6) respectively]. Examining petechiae or exudate vs. exudate alone increases OR from 1.9 to 2.9 (95% CI 2.2-3.8). Sensitivity improves (23% to 34%) with minimal change to specificity (87% to 85%). Among those with a normal or erythematous throat exam, petechiae were mentioned as a pertinent negative in 28%; absence of tonsillar exudate was mentioned in 78% (p = .02).

CONCLUSIONS

Palatal petechiae are highly associated with GAS, yet rarely addressed in documentation. Incorporating palatal petechiae into common scoring systems could improve prediction and disseminate this knowledge into practice.

Impact of viral symptoms on the performance of the modified centor score to predict pediatric group A streptococcal pharyngitis

BACKGROUND

Clinicians use the Modified Centor Score (MCS) to estimate the risk of group A streptococcal (GAS) pharyngitis in children with sore throat. The Infectious Diseases Society of America (IDSA) recommends neither testing nor treating patients with specific viral symptoms. The goal of this study is to measure the impact of those symptoms on the yield of GAS testing predicted by the MCS.

METHODS

Retrospective cohort study of all patients aged 3-21 years presenting with sore throat and tested for GAS in a pediatric emergency department (ED) in 2016. After identifying all patients tested for GAS, we used natural language processing (NLP) to identify the subgroup complaining of sore throat. We abstracted all MCS variables as well as symptoms suggestive of a viral etiology per the IDSA guideline (conjunctivitis, coryza, cough, diarrhea, hoarseness, ulcerative oral lesions, viral exanthema). We calculated the proportion of patients who tested positive for GAS by MCS with and without viral symptoms.

RESULTS

Of the 1574 patients included, 372 patients (24%) tested GAS positive. Patients with at least one viral symptom had a reduced GAS risk compared to those without any of the viral symptoms 91/547 (17% GAS positive) vs. 281/1027 (27%), odds ratio 0.53 (95% CI 0.41-0.69).

CONCLUSIONS

The presence of viral symptoms specified by the IDSA alters the predicted yield of testing by traditional MCS. Clinicians may consider adjusting interpretation of a patient's MCS based on the presence of viral symptoms, but viral symptoms may not always fully obviate the need for GAS testing.