Statistical Considerations in the Sampling of Escherichia coli from Intestinal Sources for Serotyping

Abstract

A theoretical study of the expected distribution of Escherichia coli serotypes among samples randomly drawn from populations containing different numbers, ranging from 2 to 40, was compared with experimental data based on the examination of 10 and 100 coiony samples from the same specimens. From these studies it was possible to lay down guide lines for the planning of efficient sampling programmes for determining most or all serotypes present in various animal species.

Mucosal-associated bacterial flora of the intestine in patients with Crohn's disease and in a control group

“…We found, however, that, among the isolates from Crohn's tissue, there appeared a greater pro-portion of aerobic bacteria. As we have examined 10 colonies per specimen and as, in this context, we are dealing with only two types of bacteria (aerobic and anaerobic), it is probable that these observed frequences are a valid estimate of the total population of bacteria (Hedges et al, 1977). No test was made for carbon-dioxide dependent organisms and, therefore, if such bacteria were present, they would be among those growing anaerobically.…”

An analysis of the diversity ofHaemophilus parainfluenzaein the adult human respiratory tract by genomic DNA fingerprinting

“…Thus, examination of 25 colonies per sample gives a 90 % probability of detecting at least 1 member of each of 7 strains, if these are present in equal proportions and sampling is random [24]. The actual proportions of different strains present largely determines the likelihood of detecting each strain, with unequal proportions increasing the sample size required.…”

Attempts to Displace the Indigenous Antibiotic Resistant Gut Flora of Chicken by Feeding Sensitive Strains of Escherichia coli Prior to Slaughter

“…In the United Kingdom, for example, no dramatic decrease in the incidence of antibiotic resistant Escherichia coli has occurred since the implementation of the Swam Committee recommendations (Anon. 1969;Smith 1975;Linton 1977~). There are two possible reasons for this.…”

“…Antibiotic resistant E. coli reach man by way of the food chain (Linton 1977a), the principal sources of infection being calves (Howe & Linton 1976), pigs (Linton et al 1977) and poultry (Linton 1977~). Sheep and adult cattle are not usually implicated (Howe et al 1976~).…”