Relationship of an epidemic strain of Escherichia coli O125.H21 to other serotypes of E. coli during an outbreak situation in a neonatal ward.
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Biomedical subjects
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Topical medicaments used by patients with diseases of the skin were examined for microbial contamination. Ps. aeruginosa was isolated from stock pots of a diluted emulsifying ointment used as a soap substitute in the bath. Cross-contamination between patients and medicament was subsequently shown to have occurred.
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.
One thousand, nine hundred and seventy-seven pharmaceutical products used in the home were examined for microbial contamination. Viable micro-organisms were recovered from 14.0% of samples. Medicines used in the home are apparently not exposed to the same opportunities for contamination as those used in hospital.
Topical medicaments used in the treatment and prevention of pressure sores in patients in three hospitals were examined for Pseudomonas aeruginosa and Staphylococcus aureus contamination. Contamination rates were found to vary between hospitals and were affected by differences in the packaging of the product and in the method of application used by the nursing staff.
Two hundred strains of Staphylococcus aureus isolated from outpatients with infections of the skin and subcutaneous tissues were tested for sensitivity to penicillin, erythromycin, tetracycline, sodium fusidate, methicillin, clindamycin, chloramphenicol, and gentamicin. One hundred and sixty-three (81.5%) of the strains were resistant to penicillin and 16 (8%) resistant to tetracycline. Incidence of resistance to other antibiotics was low. No strain was resistant to chloramphenicol, gentamicin, or methicillin. When compared with results of earlier studies, there was an increase in the incidence of resistance to penicillin and tetracycline, but no appreciable increase in resistance to other antibiotics.
In a study on the serotypes of Escherichia coli which are present in the faeces of students travelling from many parts of the world to Dublin, a great variety of types was found. It was not possible to relate certain types to the various parts of the world where the students came from. There was no decrease in variety of serotypes after the students had been in Dublin for a few months and no distinctive 'Dublin' types were acquired. Serological variation of the E. coli was suggested as partially explaining some of the variety of the serotypes found. Although eight students developed diarrhoea without an aetiological agent being isolated after arrival in Dublin, no distinct pattern of E. coli could be related to this.
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 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.
Pseudomonas aeruginosa was recovered from three hospital-prepared medicaments being used on the wards. Sixty-six patients were studied to observe the effect of using these contaminated medicaments. Psaeruginosa was recovered from 29 patients; in five the strains recovered bore a close resemblance to strains previously isolated from the contaminated medicaments.
The environments of hospital pharmacies and the preparations made in these pharmacies were examined for Pseudomonas aeruginosa. This organism was widely distributed in the pharmacies and was isolated from 9% of preparations. In 11 instances strains of Ps aeruginosa from the preparations bore a close resemblance to strains previously found in the pharmacy environments.
Eight babies all delivered by Caesarean section were observed for evidence of colonization by E. coli from birth until discharge from hospital 10 to 14 days later. Faecal specimens were cultured daily for E. coli as were swabs from the rectum, groin, umbilicus, head, hands und mouth. Different serotypes of E. 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 of E. coli. Serotypes of E. coli isolated from the faeces and rectum were usually isolated from the groin but less often from the umbilicus. Other sides were rarely colonized. In all instances except one the primary site of colonization appeared to be the gastrointestinal tract. Colonization by E. coli was influenced by antibiotic therapy and possibly by the method of feeding.
The sources from which eight Caesarean section babies acquired E. 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 of E. coli in premature nurseries and during outbreaks of E. coli gastroenteritis.
The Escherichia coli isolated from faecal and nasal swabs from all babies present in a maternity ward were serotyped and their anbitiotic resistance patterns and fermentation characteristics with six carbohydrates were determined. These were compared with E. coli isolated from hands and clothing of attendants and samples of ward air. The results suggest that mothers may be the primary source of E. coli in the ward but the colonized babies themselves provide the main reservoir of nursery E. coli. As most of these serotypes of E. coli were found on the attendant's hands or clothing or in the air, it is difficult to assess transmission routes for E. coli, particularly as some strains appear to possess a greater inherent ability to colonize babies than others. By the use of markers other than O antigens it was possible to characterize strains to a far greater extent.
The serotypes of 13,139 strains of Escherichia coli isolated from humans were compared with the serotypes of 1076 strains isolated from animals. 689 of these strains were isolated from fresh cow-pats on 22 sites in England and Wales. 708 different O/H combinations were found. Of these, 520 were found in human strains only, 130 from animal strains only and 58 O/H serotypes from humans and animals. Approximately half of the animal strains could not be typed with the full set of sera used.
Studies in a newly built hospital furnished with complete air conditioning where most of the patients are nursed in 6-bed rooms showed that the transfer of air from one patient room to another was very small, especially when there was substantial flow of air in a consistent direction between the patient rooms and the corridor, and that the direct transfer of airborne particles was even less. There was, however, no evidence of any reduction in the rates of nasal acquisition of Staphylococcus aureus compared with those to be found in naturally ventilated hospitals. The numbers of Staph. aureus found in the air of a given room that appeared to have originated from patient carriers in other rooms were many times greater than could be accounted for by direct airborne transfer. Although there was evidence that many carriers were not detected, detailed study showed that this excess transfer to the air of other rooms was genuine. It seems probable on the basis of investigations in this hospital and elsewhere that this excess transfer occurs indirectly, through dispersal from the clothing of the nursing and medical staff into the air of another room of strains with which their outer clothes have become contaminated while dealing with patients. Reduction in direct airborne transfer of micro-organisms from one room to another, whether by ventilation or other means, can only be of clinical advantage if transfer by other routes is, or can be made, less than that by the direct airborne route.
A total of 2525 strains of Escherichia coli were isolated from the faeces of 33 mothers, the faeces of their babies and the mucus extracted from the babies' mouths after delivery. Of these strains 1832 could be O-serotyped with 150 O antisera. E. coli were isolated from 28 babies and the same serotypes as were found in their mothers were found in 22 of them. E. coli was isolated from only 14 of the mucus specimens but in 12 of these at least one of the serotypes present was subsequently found in the babies' stools.
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.