Page 124 - 15Diarrhoeaandvomiting

Antibiotic therapy

Evidence summary

No evidence in children younger than 5 years was identified. However, results from a systematic
review found that antibiotic treatment was effective in reducing the duration and severity of
diarrhoea in adult patients with traveller’s diarrhoea, although there was an increased incidence
of side effects.

7.9 Groups for whom antibiotic treatment may be indicated

Clinical question
Are there any particular circumstances where antibiotics should be given?

Evidence overview
Searches were conducted for observational studies and 203 references were returned. On the
basis of the titles and abstracts, 33 were retrieved in full copy for further examination. Of these,
four studies were included here.

7.9.1 E. coli O157:H7
Two relevant studies were identified with regard to this pathogen, which is the main cause of
haemolytic uraemic syndrome (HUS).

One prospective cohort study 156 conducted in the USA investigated whether antibiotic treatment
affected the risk of HUS in children. [EL = 2+] In total, 71 children younger than 10 years
who had diarrhoea caused by E. coli O157:H7 were recruited to the study. Stool culture was
obtained within the first 7 days of illness. On confirmation of E. coli O157:H7, investigators
sought consent and recruited the infected child to the study. A questionnaire was administered to
caregivers to record previous and ongoing clinical signs and symptoms, prescription and other
medications taken (for example antibiotics and antimotility drugs). Prescription of medications
was at the discretion of each physician and was confirmed retrospectively from notes. Only the
initial temperature readings and laboratory test results were used for analysis. Daily blood counts
and renal function tests were performed until HUS developed and resolved or until diarrhoea
resolved. Multivariate regression analysis was used to evaluate the risk of HUS after adjustment
for two risk factors that had been previously reported to be associated with it – the initial white
cell count and the day of illness on which initial stool cuture is taken. The two groups of children
– those who received antibiotics (n = 9) and those who did not (n = 62) – were similar for
demographic characteristics, clinical and laboratory sparameters at the baseline. Overall, 10/71
(14%) developed HUS. Of the nine children who received antibiotics, five (56%) subsequently
developed HUS while of the 62 who did not receive antibiotics, five (8%) developed HUS. This
difference was statistically significant (P = 0.001) and remained so after adjustment, although
confidence intervals were wide and the lower estimate was close to unity. (Antibiotics given
within the first 7 days after onset RR 17.3; 95% CI 2.2 to 137; P = 0.007, and within the first
3 days after onset RR 32.3; 95% CI 1.4 to 737; P = 0.03). A statistically significant linear trend was
observed for initial white blood cell count and development of HUS (P = 0.005). This remained
statistically significant after reanalysis as a continuous outcome and adjustment (adjusted RR 1.5;
95% CI 1.1 to 2.1; P = 0.02). A statistically significant linear trend was also observed for the
difference in HUS development according to the day that stool culture was taken (P = 0.01). This
remained statistically significant after adjustment (adjusted RR 0.3; 95% CI 0.1 to 0.7; P = 0.008).
A retrospective cohort study, 157 also conducted in the USA, evaluated risk factors for progression
of E. coli O157:H7 to the development of HUS. [EL = 2+] Participants were younger than 16 years,
resided in Washington state and either had symptomatic, culture-proven E. coli O157:H7 infection
or had developed HUS in January or February 1993 (during an E. coli O157:H7 outbreak from
a ‘fast food outlet’ chain. Demographic, symptomatic and medication data were gathered from
three sources: two telephone questionnaires administered to participants’ parents (within 2 weeks
of illness onset and 2–4 months later) and from examination of patients’ medical records. Cases
and controls were similar for age, sex and annual family income at baseline. The median age of

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