Presenting clinical features and c-reactive protein in the prediction of apositive stool culture in patients with diarrhoea

Objectives: To devise a scoring system by which clinical features and C-rea ctive protein (CRP) can be used to predict a positive stool culture in pati ents admitted with acute diarrhoea. Methods: One hundred and thirty-two patients admitted to the Regional Infec tion Unit with diarrhoea thought to be due to bacterial gastroenteritis wer e included. Clinical features, CRP and outcome of stool culture were record ed, together with the final diagnosis. Results: Forty-one patients had bacterial gastroenteritis characterized by the isolation of a bacterial enteropath (BGE). Sixty-three patients had non -specific gastroenteritis, defined as more than three loose stools per day with no bacterial enteropath isolated (NSGE). In 28 patients another diagno sis was made (Others). More of the patients with BGE (91%) had abdominal pa in as compared with those with NSGE (67%) and Others (61%) (P < 0.01). The mean duration of symptoms was longer in the Others group (6.14 days) as com pared with patients with BGE (3.29) and NSGE (3.25) (P < 0.01). The mean CR P was significantly higher in those with BGE (113.9 mg/l) and Others (116.9 mg/l) as compared to the NSGE patients (38.9 mg/l) (P < 0.001). A scoring system was devised which incorporated the presence or absence of abdominal pain (+ 10 or 0), the duration of symptoms (-10, for 5 or more days, 0 for less than 5 days of symptoms) and the CRP (CRP < 50 = 0, CRP > 50 = 5). A s core of 15 or more predicted 79% of patients with BGE, while a score of 15 predicted 87% of those with NSGE and 86% of those with another diagnosis. Conclusions: This simple scoring system may be useful in predicting the pos itivity of stool culture, and therefore may be helpful in targeting those s mall number of patients who require antimicrobial therapy after hospital ad mission. We would not, however, favour reliance on this scoring system alon e to choose whom to treat with antimicrobials. (C) 2000 The British Infecti on Society.