K. A. Bettelheim

SEROTYPES OF ESCHERICHIA COLI IN NORMAL STOOLS

Abstract 1580 strains of Escherichia coli from 10 sites of nine specimens of faeces were O serotyped. In all stools except one there was a single predominant type present at all sites and constituting more than half the colonies isolated. However, from seven specimens more than one serotype was isolated, and from one specimen as many as eleven different serotypes could be distinguished.

Spread of Escherichia coli colonizing newborn babies and their mothers.

Most babies are colonized by the predominant strains of Escherichia coli present in their own mothers faecal flora. Those babies who did not acquire their maternal faecal flora acquired strains of E. coli belonging to a small number of the possible serotypes. Moreover, the same serotypes were found in several babies and other mothers, suggesting spread within the ward. These few strains included some of the O groups which had previously commonly been found as urinary pathogens. These strains may have increased potentialities for colonization of human bowel. Antigenic and biochemical variation was observed among the strains.

Further studies of Escherichia coli in babies after normal delivery.

Previous work showed that on the basis of O serotyping alone of Escherichia coli, the majority of babies acquired the same O serotype as was found in the stools of their respective mothers. Further characterization of the E. coli by H serotyping, determination of their antibiotic resistance and ability to ferment six carbohydrates showed that in the majority of cases the previous results were confirmed. In a minority of cases this further testing showed that the strains were not identical. In some instances a number of strains isolated from the same pair showed different combinations of the markers used.

Escherichia coli isolated from babies delivered by caesarean section and their environment.

SummaryThe sources from which eight Caesarean section babies acquiredE. coli are described and the probable routes by which the organisms reached the babies are outlined. Suggestions are made concerning the control of the spread ofE. coli in premature nurseries and during outbreaks ofE. coli gastroenteritis.ZusammenfassungDer Ursprung vonE. coli Stämmen, die von Kindern nach einer Sectio isoliert werden konnten, und der wahrscheinliche Weg zu den Neugeborenen werden aufgezeigt. Es werden Vorschläge gemacht, um die Ausbreitung vonE. coli in Frühgeborenenstationen und bei Ausbrüchen vonE. coli-Gastroenteritiden unter Kontrolle zu bringen.

The effect of diet on intestinal Escherichia coli.

During an 8-week period all specimens of stool passed by six nurses were examined for the presence of Escherichia coli and all isolations of this organism were serotyped. During the middle 4 weeks of the period the nurses ate a sterile diet. A smaller number of serotypes was isolated during the period of sterile diet than during the period when normal food was eaten. This finding supports the view that normal food is a source of strains of E. coli present in the bowel. Some new serotypes of E. coli did appear during the period of sterile diet. The possible sources of these are discussed.

Serological studies of Bacteroides fragilis.

Using direct agglutination methods, a simple serological scheme for the classification of Bacteroides fragilis is described. Twenty strains of B. fragilis were selected by a process of sucessive screening from 151 strains obtained from various sources. O-antigens were prepared from the 20 strains, and used to raise antisera in rabbits. Each of the 20 antisera reacted with its homologous antigen and eight antisera cross-reacted with other subspecies. These cross-reactions were successfully removed after absorption of the antisera with the cross-reacting antigens, resulting in 19 type-specific antisera, titres ranging from 40 to 320, and 19 distinct serotypes of B. fragilis. There was no correlation between the antigenic and the biochemical characteristics of these strains and no cross-reactions occurred with other gram-negative anaerobes, B. melaninogenicus, Sphaerophorus necrophorus and Fusobacterium necrogenes.

The isolation of Escherichia coli from a poultry packing station and an abattoir.

The distribution and serotype of strains of Escherichia coli from a poultry packing station and an abattoir are described. The results indicated that animal faecal strains contaminated the environment and the animal carcasses.Using 150 O antisera, a high proportion of the E. coli strains were non-typable. This suggests that the serotype distribution of E. coli in animals is different from that in man.Strains with single antigenic differences were isolated, and the possibility of genetic transfer of these antigenic structures is suggested.

Escherichia coli serotypes in the faeces of healthy adults over a period of several months

The faeces of nine subjects eating mainly at home were collected at regular intervals over periods ranging from 2--5 months. Although a large number of serotypes of E. coli were isolated, the variety per subject was lower than is usually found. In most subjects only a limited number of serotypes persisted over most of the periods of study while many serotypes were only isolated on single occasions.

Colonization of caesarean section babies by Excherichia coli.

SummaryEight babies all delivered by Caesarean section were observed for evidence of colonization byE. coli from birth until discharge from hospital 10 to 14 days later. Faecal specimens were cultured daily forE. coli as were swabs from the rectum, groin, umbilicus, head, hands und mouth. Different serotypes ofE. coli were isolated from four babies on day 1, one baby on day 2, one baby on day 7 and two babies on day 9. Three babies excreted more than one serotype ofE. coli. Serotypes ofE. coli isolated from the faeces and rectum were usually isolated from the groin but less often from the umbilicus. Other sites were rarely colonized. In all instances except one the primary site of colonization appeared to be the gastrointestinal tract. Colonization byE. coli was influenced by antibiotic therapy and possibly by the method of feeding.ZusammenfassungAcht Neugeborene, die durch eine Sectio entbunden wurden, kamen im Hinblick auf ihreE. coli-Besiedlung von der Geburt bis zur Entlassung zu einer kontinuierlichen Beobachtung. Es wurdenE. coli-Untersuchungen vom Stuhl sowie von Rektal-, Leisten-, Nabel-, Kopf-, Hand- und Mundabstrichen durchgeführt. Von vier Säuglingen wurden am 1. Tag verschiedeneE. coli-Serotypen isoliert, bei einem Neugeborenen am 2. Tag, bei einem Neugeborenen am 7. Tag und bei zwei Neugeborenen am 9. Tag. Drei Säuglinge schieden mehr als einen Serotyp aus. Die Serotypen, die aus dem Stuhl und Rektum isoliert wurden, konnten in der Regel aus der Leistenbeuge, jedoch weniger häufig vom Nabel isoliert werden. Andere Lokalisationen waren selten besiedelt. Bis auf einen Fall war die Erstbesiedlung im Gastrointestinaltrakt nachweisbar. Die Kolonisierung vonE. coli wurde durch die Chemotherapie und die Ernährungsweise beeinflußt.

Studies on the enterotoxigenicity of environmental Escherichia coli, belonging to serotypes normally considered enterotoxigenic.

Fifteen strains of Escherichia coli which had been collected in previous studies from animals and meat were studied. They belonged to serotypes considered enterotoxigenic and were examined for the production of the heat-labile and heat-stable enterotoxins. Only one of these strains (O8.Hnt) isolated from a cowpat in Cheshire produced heat-labile enterotoxin. Another strain (O8.H9) isolated from a cowpat in another part of Cheshire gave results suggesting production of small amounts of the heat-stable enterotoxin. The ecological aspects of these results are discussed.