Biomedical subjects
Publications and source records attributed to K A Bettelheim.
Complement fixation has been shown to occur when asparaginase reacts with specific antibody. This is as a result of an antigenic determinant common to the four bacterial asparaginases. Patients on asparaginase therapy may produce antibodies and these could be demonstrated by complement fixation.
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.
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 O and H serotypes of Escherichia coli that were present along the entire length of the gastrointestinal tract of patients with small intestinal bacterial overgrowth were studied. Multiple sero- and biotypes were represented, although usually a single serotype predominated in each patient. In a number of cases the different O:H serotypes were antigenically related indicating that antigenic degradation was occurring. The serotypes isolated from the stomach and small intestine were represented in the faeces. In general, within the limitations of this study, there appears to be a stable ecosystem in each patient and it may require specific oral antibiotics to alter it.
A wild type strain of E. coli which produced an invertase capable of hydrolysing sucrose and raffinose transmitted this ability at high frequency to a recipient strain. E. coli C. The ability to ferment both sucrose and raffinose was lost both in the wild type parent and recombinant strains by treatment with ethidium bromide.
Bipolar staining of the trophozoites of Toxoplasma gondii has been observed with a number of sera from patients. It has been demonstrated that the serum factors involved are IgM. The majority of sera demonstrating this phenomenon had raised nonspecific IgM levels.
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.
In discussing the background of these studies the importance of faecal carriage of Gram negative organisms by hospital patients is stressed. In many instances it was shown that transmission is by an oral route. This discussion leads on to an assessment of the dose required for Escherichia coli to implant in the bowel. The difficulties of studying the spread of E. coli within a faecal specimen are discussed. A number of papers are quoted which show that E. coli are present in the vagina of women and that the acquisition of these E. coli by babies is related to the length of time that the birth takes, and that there is a relationship between the E. coli found in the faeces of the mothers, the mucus swallowed by the babies at birth and subsequently in the faeces of the babies. Most of the eralier studies quoted deal predominantly with enteropathogenic serotypes, but it was later shown that other serotypes can be similarly acquired by the babies. Although this appears to be the general method by which babies acquire their faecal E. coli, it is well established that they can also be obtained from the environment, hence ward outbreaks of infantile gastroenteritis. Studies on normally delivered babies show that generally two thirds obtain their faecal E. coli from their mothers while the rest appear to pick up environmental strains. Very detailed biochemical and serological studies need to be performed to assess this. Caesarian section babies are generally not likely to become colonized by their mothers' faecal E. coli and studies are described which show that the babies faeces or rectal swabs are usually the first areas colonized and that the E. coli are spread from there. Extensive environmental studies suggest that contaminated hands and uniforms of the nursing staff may be the main vector for transmitting E. coli. There is a wide variety of E. coli serotypes present in a maternity ward at any time and these are related to the presence of the babies excreting them. A variation in the ability of strains to spread was noted.
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.
Rabbit antisera against L-asparaginase preparations from Escherichia coli, Erwinia carotovora, Citrobacter sp. and Chromobacterium violaceum showed on immunoelectrophoresis that only the enzymes from E. coli and Citrobacter are immunologically related. Purified preparations had to be used to determine the immunological cross-reactions. Immunoelectrophoresis at different pH values yielded the zero mobility points of the enzymes. The activity of the Er. carotovora preparation was enhanced up to fourfold by homologous antiserum but not by normal sera. Heterologous antisera also enhanced, but only at a higher concentration. Less enhancement was observed for the other enzymes with antisera as well as with bovine serum albumin. Inhibition was not observed.
Strains of Escherichia coli isolated in a maternity unit were examined serologically. On primary isolation the strains were shown to be O-antigenically distinguishable, although having the same H antigen, biotype and antibiogram. Subsequent detailed serological studies revealed that the colonial variants derived from them showed similar antigenic diversity, irrespective of the original antigenic structure.
Strains of E. coli, mainly from Chinese patients in Hong Kong with urinary tract infections, were serotyped, biotyped, and their antibiotic resistance patterns determined. The most common O groups found were O1, O2, O4, O6, O7, O8, O21, O25 AND O82. In general, they carried flagellar antigens different from those normally associated with these O groups in Europe. A variety of biotypes was observed and many strains were resistant to a number of antimicrobial drugs.
An intracellular L-asparaginase with antitumour activity was purified from a strain of Citrobacter. The optimum conditions for enzyme production by fermentation on scales up to 2700 l were investigated. Highest enzyme yield was obtained in corn-steep liquor medium (9-2%, W/V) at 37 degrees C. Oxygen limitation was not necessary for high enzyme yield. A total recovery of 4-3% from nucleic-acid-free extract and a 180-fold increase in specific activity were obtained after purificaiton. The specific activity of the purified preparation was 45 i.u./mg protein. The enzyme hydrolysed D-asparagine and L-glutamine at 7 and 5%, respectively, of its activity toward L-asparagine, but L-glutaminase activity could be demonstrated only at substrate concentrations above 5 mM. The Km values for L-asparagine and D-asparagine were 2-6 X 10(-5) and 1-4 X 10(-4) respectively. The anti-lymphoma activity of the enzyme was demonstrated with Gardner lymphosarcoma and was found only slightly less potent that Crasnitin, the most active asparaginase so far tested in this system.
Three E. coli strains representing strains from faeces of normal persons were established as antigenic test strains of two new O antigens, O162 and O163, and one new H antigen, H56.
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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.