Presenting clinical features and C-reactive protein in the prediction of a positive stool culture in patients with diarrhoea.
OBJECTIVE
To devise a scoring system by which clinical features and C-reactive protein (CRP) can be used to predict a positive stool culture in patients admitted with acute diarrhoea.


METHODS
One hundred and thirty-two patients admitted to the Regional Infection Unit with diarrhoea thought to be due to bacterial gastroenteritis were included. Clinical features, CRP and outcome of stool culture were recorded, 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 diagnosis was made (Others). More of the patients with BGE (91%) had abdominal pain 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 compared with patients with BGE (3.29) and NSGE (3.25) (P=0.01). The mean CRP was significantly higher in those with BGE (113.9mg/l) and Others (116.9mg/l) as compared to the NSGE patients (38.9mg/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 score 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 positivity of stool culture, and therefore may be helpful in targeting those small number of patients who require antimicrobial therapy after hospital admission. We would not, however, favour reliance on this scoring system alone to choose whom to treat with antimicrobials.
Cadwgan
A M
AM
The Infection Unit, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, UK.
Watson
W A
WA
Laing
R B
RB
MacKenzie
A R
AR
Smith
C C
CC
Douglas
J G
JG
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002097:C-Reactive Protein / Q000032:analysis*; D003967:Diarrhea / Q000097:blood / Q000150:complications / Q000188:drug therapy / Q000382:microbiology*; D005243:Feces / Q000382:microbiology*; D005759:Gastroenteritis / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D011237:Predictive Value of Tests
D000900:Anti-Bacterial Agents; D002097:C-Reactive Protein