Sheila M. O'Farrell

TYPING SCHEME FOR CLOSTRIDIUM DIFFICILE: ITS APPLICATION IN CLINICAL AND EPIDEMIOLOGICAL STUDIES

Epidemiological studies of Clostridium difficile diarrhoeal disease have been hindered by the lack of a typing scheme for this organism. A typing method based on the incorporation of sulphur-35-labelled methionine into cellular proteins and their separation by sodium dodecylsulphate/polyacrylamide gel electrophoresis showed clear pattern differences between strains, and nine distinct groups within the C difficile species were established. 98% of 250 clinical strains derived from four hospitals were typable. Group X was the commonest group and was associated with outbreaks of pseudomembranous colitis and antibiotic-associated colitis in two hospitals. Groups A-D were isolated predominantly from mothers and newborn infants. In outbreaks of antibiotic-associated colitis in oncology and orthopaedic wards the same strains, group X and group E, respectively, were isolated from patients and their environment, providing strong evidence of cross-infection between patients and of hospital acquisition of C difficile.

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.

VAGINAL CARRIAGE AND NEONATAL ACQUISITION OF CLOSTRIDIUM DIFFICILE

The relationship between vaginal carriage and subsequent neonatal acquisition of Clostridium difficile was investigated. Vaginal carriage of C. difficile was detected in 11% of women attending the Department of Genital Medicine Clinic. C. difficile was isolated from the vagina in 18% of 50 mothers before delivery, and 8% after delivery; 62% of their babies had positive faecal cultures. Eight of nine of the babies whose mothers had positive cultures before delivery became colonised with C. difficile, while 23 of 41 babies whose mothers had negative cultures became colonised. This suggests that both the vagina and the environment may act as sources of neonatal acquisition of C. difficile. Broth enrichment culture proved a more sensitive method for isolating C. difficile from the vagina than direct plate culture and should be used in such investigations.

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.

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.