Mini Review: Opposing Pathologies in Cancer and Alzheimer's Disease: Does the PI3K/Akt Pathway Provide Clues?

This minireview is a brief overview examining the roles of insulin-like growth factors (IGFs) and the PI3K/Akt pathway in two apparently unconnected diseases: Alzheimer's dementia and cancer. For both, increased age is a major risk factor, and, in accord with the global rise in average life expectancy, their prevalence is also increasing. Cancer, however, involves excessive cell proliferation and metastasis, whereas Alzheimer's disease (AD) involves cell death and tissue destruction. The apparent "inverse" nature of these disease states is examined here, but also some important commonalities in terms of the PI3K/Akt pathway, glucose utilization and cell deregulation/death. The focus here is on four key molecules associated with this pathway; notably, the insulin receptor substrate 1 (IRS-1), cellular tumor antigen p53 (p53), peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) and low-density lipoprotein receptor-related protein-1 (LRP1), all previously identified as potential therapeutic targets for both diseases. The insulin-resistant state, commonly reported in AD brain, results in neuronal glucose deprivation, due to a dampening down of the PI3K/Akt pathway, including overactivity of the mammalian target of rapamycin 1 (mTORC1) complex, hyperphosphorylation of p53 and neuronal death. This contrasts with cancer, where there is overstimulation of the PI3K/Akt pathway and the suppression of mTORC1 and p53, enabling abundant energy and unrestrained cell proliferation. Although these disease states appear to be diametrically opposed, the same key molecules are controlling pathology and, with differential targeting of therapeutics, may yet provide a beneficial outcome for both.

Employee attitudes towards aggression in persons with dementia: Readiness for wider adoption of person-centered frameworks

WHAT IS KNOWN ON THE SUBJECT

Person-centered care, as compared to standard approaches, is a widely accepted, evidence-based approach for managing aggressive behaviour in persons with dementia. The attitudes, beliefs and values of long-term care and mental health nursing employees are important prerequisites to implementing person-centered practices. Research shows that nursing employees typically support person-centered approaches; however, less is known about the attitudes of non-nursing employee groups.

WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE

Nurse managers and administrators tended to agree with person-centered approaches for managing aggression in dementia, suggesting some prerequisites are in place to support wider adoption of person-centered frameworks. Employees with more resident contact tended to support person-centered approaches the least, suggesting discipline-specific trainings may not be adequate for preparing frontline staff to use person-centered techniques. Attitudes towards aggressive behaviour may be especially varied and contradictory within certain employee groups, providing implications for facility-wide initiatives.

IMPLICATIONS FOR PRACTICE

Person-centered values and practices should be monitored and reinforced across the organization. Person-centered trainings should be interdisciplinary in nature and focused on care areas, such as mealtime or bathing. Long-term care facilities should consider allowing nurse management and registered nurses to share the burden of direct resident care with frontline employees on a more regular basis.

ABSTRACT

Introduction Implementing person-centered care requires shared attitudes, beliefs and values among all care employees. Existing research has failed to examine the attitudes of non-nursing employees. Aim This study examined attitudes towards aggression among nursing and non-nursing employees to address gaps in existing research and assess readiness for wider adoption of person-centered frameworks. Method The Management of Aggression in People with Dementia Attitude Questionnaire was used to survey attitudes of employees in Michigan-based nursing homes. Results Overall, employees preferred person-centered over standard approaches. Job title was a significant predictor of paradigm support. Frontline employees were found to support person-centered attitudes the least. Wide-ranging responses were noted within employee groups. Discussion Job title may influence the degree to which an employee supports and utilizes person-centered approaches. Employees with the most contact with persons with dementia may be the least likely to implement person-centered approaches. In contrast to prior studies, years of experience was not a significant predictor of attitude towards aggressive behaviour. Wide-ranging responses indicate that employee attitudes are varied and complex. Implications Person-centered approaches should be trained within care areas rather than individual employee groups. Programs should be interdisciplinary and seek to establish a shared understanding of person-centered beliefs and values.

Preparedness for a major incident: creation of an epidemiology protocol for a health protection register in England

Large incidents and natural disasters are on the increase globally. They can have a major impact lasting many years or decades; and can affect large groups of people including those that are more susceptible to adverse consequences. Following a major incident, it may be considered necessary to establish a register of those people affected by the incident to provide appropriate advice on relevant immediate and longer-term public health interventions that may be required, provide reassurance to the public that their care is paramount, to reassure the worried well to avoid them inappropriately overwhelming local services, and to facilitate epidemiological investigations. Arrangements for the prompt follow-up of populations after large incidents or disasters have been agreed in England and a protocol for establishing a register of individuals potentially affected by a large incident has been developed. It is important for countries to have a protocol for implementing a health register if the circumstances require one to be in place, and are supported by Public Health Authorities. Health registers facilitate the initial descriptive epidemiology of exposure and provide the opportunity of carrying out long term analytical studies on the affected population. Such epidemiological studies provide a greater understanding of the impact that a large incident can have on health, which in turn helps in the planning of health care provision. Registers can also assist more directly in providing access to individuals in need of physical and mental health interventions. The challenge that still remains is to formally pilot the register in the field and refine it based on that experience.

A note on effectiveness of dry cow therapy in New Zealand dairy herds

Two dry-cow therapy products were evaluated in seven factory-supply dairy herds in the Waikato area. A product containing neomycin sulphate and the benzathine salt of penicillin (Neopen D.C. White; Smith-Biolab) was used in five herds, and one containing benzathine cloxacillin (Orbenin, Beecham) was used in two herds. Non-treated control cows were included in each herd. Both products were effective in eliminating intramammary infections with Staphylococcus aureus, Streptococcus uberis, and Streptococcus agalactiae. Efficacy of dry-cow therapy against S. aureus was 83.8% and 85.2% respectively. Spontaneous cure rate among controls was 30.8% for S. aureus during the dry period. Spontaneous cure rate for Str. uberis was 50%, while dry-cow therapy eliminated 100% and 77.8%, respectively, for the two products. Dry-cow therapy with either product eliminated more than 90% of Str. agalactiae infections while spontaneous cure rate was only 28.6%. These results further support the effectiveness of dry-cow therapy in reducing the level of subclinical mastitis in dairy herds by shortening the duration of intramammary infections.

Comparative efficacy of dry-cow treatment regimens against Staphylococcus aureus

Four dry-cow treatment regimens were evaluated against Staphylococcus aureus intramammary infections: 1) high persistency product at drying off and low persistency product 1 to 3 days prepartum; 2) high persistency product at drying off; 3) low persistency product 1 to 3 days prepartum; 4) untreated controls. Treatment 1 was no more efficacious (64.4%) than Treatment 2 (61.3%). Both treatments were significantly different from spontaneous recovery observed in Treatment 4 (41.2%), but not significantly different from Treatment 3 (46.9%). Dry-cow therapy reduced new S. aureus intramammary infections during the dry period by half. Prepartum treatment eliminated more than 90% of new Streptococcus uberis infections.

Risk factors for meningococcal disease in university halls of residence

A retrospective ecological study was undertaken to identify social and environmental factors associated with increased incidence of meningococcal disease in university halls of residence. A standardized questionnaire was sent to UK universities and colleges of higher education outside London, for distribution to halls containing at least 50 students. Incidence rate ratios of invasive meningococcal disease were obtained for a range of social and environmental variables. Multi-variable Poisson regression analysis identified 3 factors as having a strong association: a high proportion of first year undergraduate residents (P = 0.0008), decreasing smokiness of the hall bar (P < 0.0001), and opening of hall bar before 1990 (P = 0.0001). The inverse relationship between disease incidence and smokiness of bars was an unexpected finding, and may be due to confounding factors. Universities should continue to promote awareness of meningococcal disease, encourage vaccination of first year students against serogroup C disease, and where appropriate, take measures to reduce overcrowding.

Practical guidelines for responding to an outbreak of meningococcal disease among university students based on experience in Southampton

Six students at the University of Southampton developed meningococcal disease in October 1997, five of them with confirmed serogroup C infections, and three died. The outbreak had major organisational and financial implications for the agencies involved. Detailed planning and good working relationships with the management of higher educational institutions can prove invaluable in such situations. This paper summarises the management of the outbreak in Southampton and presents recommendations based on our experience.

MAFF statutory incident reports in surveillance, prevention, and control of human Salmonella typhimurium infection

We surveyed consultants in communicable disease control (CCDCs) for their views on the current and potential value of Statutory Incident Reports--Salmonella in Animals, Birds and their Products received from the Ministry of Agriculture Fisheries and Food (MAFF), in the surveillance, prevention, and control of Salmonella typhimurium infections in humans. CCDCs from 103 (83%) of 124 district health authorities responded. Most CCDCs in rural areas used the reports either to cross reference information about animal and human isolates or to discuss with environmental health officers. Many believed that the reports' relevance to human infection could be improved if they were sent more quickly. Some CCDCs suggested that it would be useful to cross reference laboratory reports of animal and human infection at regional level and to have personal contact with local veterinary officers of MAFF. Close cooperation between public health doctors and MAFF and a coordinated approach is needed to prevent and control associations between animal and human zoonotic infections.

The prevalence of mastitis in primiparous heifers in eleven Waikato dairy herds

The objective of the study was to determine the prevalence of mastitis among primiparous heifers at calving and at drying off in 11 Waikato dairy herds during the 1993-94 dairy production season. Duplicate quarter milk samples were collected aseptically from 458 heifers within 5 days after calving for bacteriological analysis. Mastitis was diagnosed in at least one quarter in 35.6% of these heifers. Coagulase-negative staphylococci were isolated from 21.8% of the heifers. The prevalence of coagulase-negative staphylococci varied between herds from 4.3% to 44.8%. Environmental streptococci caused mastitis in 12.2% of heifers, ranging from 5.6% to 24.1% between herds. Streptococcus uberus was the pathogen identified most frequently at calving and accounted for more than 90% of the streptococcal isolates. Staphylococcus aureus and coliforms were isolated from less than 1% of samples. Clinical mastitis was observed in 8.1% of heifers at calving; environmental streptococci were isolated from 67.6% of these clinical clinical cases. Only 2.8% of heifers developed clinical mastitis during lactation and environmental streptococci were isolated from 38.5% of these cases. The prevalence of mastitis among 428 of the heifers at drying off was 64.7%; a 1.8 fold increase during lactation. Corynebactetium bovis was isolated from 43% of heifers at drying off even though it was not isolated from any heifers at calving. During the season, the prevalence of Staphylococcus aureus mastitis increased to 2.8% while mastitis caused by environmental streptococci declined to 2.8%. The prevalence of environmental mastitis pathogens decreased during lactation while contagious pathogens increased in each of the 11 herds. Ineffective post-milking teat sanitation probably contributed to the increase in mastitis caused by contagious pathogens. Specific factors were not determined that affected the variation in prevalence between herds.

Associations between human and farm animal infections with Salmonella typhimurium DT104 in Herefordshire

Reports of human infection with Salmonella typhimurium definitive type (DT) 104 have generated considerable interest. We undertook a descriptive study of infections with S. typhimurium DT 104 infection in humans and farm animals in Herefordshire between 1991 and 1993. Laboratory reports of human salmonellosis, sent to the consultant in communicable disease control, were compared with cases identified using Statutory Incident Reports of salmonella in animals, birds and their products, received from the Ministry of Agriculture, Fisheries and Food. Six separate associations of infection between farming families and their livestock were identified. Nine out of 23 human cases, including three family outbreaks, were associated with animal infection. This study suggests that occupationally acquired infection in farmers and their families may be contributing to the national increase in cases, and shows the value of drawing together data from human and animal sources for the surveillance, investigation, and control of human infection with S. typhimurium DT104.

Genetic population structure, clonal phylogeny, and pathogenicity of Salmonella paratyphi B

Genetic diversity and relationships among 123 strains of Salmonella paratyphi B (serotype 1,4,[5],12:b:[1,2]) were estimated from an assessment of electrophoretically demonstrable allelic variation at 24 chromosomal enzyme gene loci. Fourteen electrophoretic types, marking clones, were distinguished, the phylogeny of the clonal lineages was reconstructed, and biotype and other phenotypic characters were mapped onto this structure. Most d-tartrate-negative strains are members of an abundant, globally distributed clone (Pb 1) that is polymorphic for many biotype characters (including d-tartrate utilization), bacteriophage type, rRNA pattern, and colicin M and phage ES18 sensitivity. This clone is largely responsible for S. paratyphi B enteric fever in humans. In contrast, d-tartrate-positive strains (formerly known as S. java) occurred in all seven of the clonal lineages identified by population genetic analysis, although most d-tartrate-positive isolates belong to only two clones (Pb 3 and Pb 4), which vary in frequency geographically. Monophasic strains represent four closely related clones forming a distinctive phylogenetic lineage. The Kauffmann hypothesis of convergence in serotype among distantly related cell lineages through recombination (via phage transduction or other means) may account for the considerable genotypic diversity among clones of S. paratyphi B. Pb 4, Pb 6, and Pb 7 are more closely allied with clones of S. typhimurium and S. saintpaul than with other clones of S. paratyphi B. Sensitivity or resistance to colicin M and phage ES18 and the electrophoretic pattern of the rRNA, which were incorporated into a recently proposed scheme for the identification of types of S. paratyphi B, individually or in combination fail to mark clones or other meaningful phylogenetic subdivisions.

Incidence of cancer in Bradford Asians

STUDY OBJECTIVE

The aim of the study was to investigate the incidence of cancer in Asians living in Bradford.

DESIGN

Cancer registrations were obtained from the Yorkshire Regional Cancer Registry for the six year period 1979-1984. Registrations relating to persons of Asian background were extracted using forenames and surnames. Data were analysed by disease category and age and sex specific incidence rates were calculated. These were compared with expected incidence rates for the non-Asian population and with rates for the Indian subcontinent derived from the Bombay Cancer Registry.

SETTING

Data collection was confined to the Bradford Metropolitan District, population 449,897 (1981).

SUBJECTS

The Asians studied originated from Pakistan (65%), India (28%), Bangladesh (4%), and East Africa (3%). The total Asian population of the Bradford Metropolitan District was approximately 45,000.

MAIN RESULTS

Over the study period there were 178 Asian cancer registrations. The overall standardised registration ratio was 53.7 for males (100 cases, 95% confidence interval 43-64), and 43.5 for females (78 cases, 95% CI 34-53). The standardised registration ratios for cancer of the hypopharynx in males and gall bladder in females were significantly raised. There was a particularly low incidence of cancer of the stomach, large bowel, lung, skin, and bladder in males, and of skin, breast, cervix (in situ), and ovary in females. The analyses suggested that lung and breast cancer incidence may be increasing towards the non-Asian level. In situ cancer of cervix in Asians shows no evidence of the high rates found in younger non-Asian age groups.

CONCLUSIONS

Lower incidence of many cancers in Asians may be due to lower exposure to major risk factors. Demographic change resulting in increased exposure to these risk factors can be expected to result in an increase in cancer incidence in Asians.

Numerical index of the discriminatory ability of biotyping for strains of Salmonella typhimurium and Salmonella paratyphi B

An index of discrimination was used to assess the discriminatory power of biotyping for salmonellas of selected serotypes. Three collections of phage-typed strains of Salmonella typhimurium and Salmonella paratyphi B, previously tested for biotype, were examined. The results established that the discrimination index was high when full biotyping alone was used for differentiation of strains from international series. When biotyping was combined with phage typing, the discrimination achieved was greater than for either method used alone. These findings confirm that biotyping affords excellent discrimination of strains of S. typhimurium and S. paratyphi B and indicate that the results obtained from biotyping can be interpreted with confidence.

Persistent and transient clones of Salmonella typhimurium of phage type 141 recognized by biotyping

Among the 81 cultures of Salmonella typhimurium of phage type 141 examined, 72 had been isolated from Sheffield incidents in 1984-5 and 9 were Scottish isolates from 1986-7. All of these cultures from diverse sources belonged to primary biotype 31; 79 were of full biotype 31beg and 2 anaerogenic cultures were of full biotype 31begj. This is the first known occasion on which an epidemic strain of S. typhimurium of phage type/biotype 141/31beg has been implicated in outbreaks of human or animal infection in the UK. Because previous epidemic strains of S. typhimurium of phage type 141 in the UK belonged to biotypes 1f and 9f which are phylogenetically unrelated to biotype 31beg, the likely origin of this most recent epidemic S. typhimurium strain of phage type/biotype 141/31beg is discussed.

Types of Salmonella paratyphi B and their phylogenetic significance

The substrates inositol, rhamnose, d-tartrate and m-tartrate used in fermentation tests with 338 cultures of Salmonella paratyphi B differentiated strains in some phage types to give information that could be used in epidemiological investigations. Xylose in Bitter's medium, the fifth substrate by which 13 of a potential 32 biotypes were identified, differentiated few cultures with the negative character. The possession of a specific type of outer-membrane protein receptor for colicin M or bacteriophage ES18 and the particular type of ribosomal ribonucleic acid present, defined three groups among the phage-typed and biotyped cultures. The possibility that the serotype S. paratyphi B contains clones of different phylogenetic origin and the consequent implications for nomenclature are discussed.

Abortive phage-infection and UV-protection markers on Col I plasmids from epidemic strains of Salmonella

Cultures of Escherichia coli carrying ColI plasmids received in conjugation from strains of Salmonella typhimurium and S. agona were examined for abortive infection (Abi) of phage BF23 and for enhanced resistance to the lethal action of UV-irradiation (Uvr). The Abi character of stored cultures of E. coli was also compared with the reaction of the same stock culture tested 5 years before. Seven of the eight potential types differentiated by three characters were represented among 160 ColI plasmids: ColIa Abi+ Uvr+ (3 plasmids), ColIa Abi- Uvr+ (1), ColIa Abi- Uvr- (2), ColIb Abi+ Uvr+ (85), ColIb Abi+ Uvr- (5), ColIb Abi- Uvr+ (4), ColIb abi- Uvr- (60). Recognition that different plasmid types could be carried by strains of a clone proved useful in the interpretation of the epidemic spread of strains of S. typhimurium of phage type/biotype 141/9f in Scotland and in tracing the ancestry of a recently emerged rhamnose non-fermenting mutant strain of S. agona.

Old and new techniques together resolve a problem of infection by Salmonella typhimurium

Isolates of Salmonella typhimurium, recovered over a 9-month period from a child with gastroenteritis, were characterized by biotyping, phage-typing and plasmid-profile analysis. Because the data from the different methods were discrepant, it was difficult to establish whether her infection was due to a single strain that had changed character in vivo or was due to recurrent infections with different, unrelated strains. Restriction-enzyme fingerprinting of the plasmids from the different isolates provided an explanation for the initial discrepancy and high-lighted a source of potential confusion in epidemiological studies.

Tracing Salmonella typhimurium infections

Since the low point of 1977 the incidence of infection attributed toSalmonella typhimuriumin England and Wales has shown a steady increase with a total of 4956 cases reported in 1982 (OPCS, 1985). Although the number of general outbreaks and family outbreaks increased by 24 % and 54 % respectively between 1981 and 1982, the greatest increase (55%) was in the number of sporadic cases reported (PHLS, 1984). The cause of the recent increase in human infection is not known but may be associated with bovine infection and an explanation for the rise in sporadic cases could be that they comprise unrecognized outbreaks due to common food products distributed over wide geographical areas for long periods of time because of deep freezing (Galbraith, 1985). This hypothesis has prompted the Communicable Disease Surveillance Centre to mount a case-control study comparing sporadic cases ofS. typhimuriuminfection with an unaffected control group in several parts of the country to find the vehicles of infection. Such an approach requires precise strain identification and detailed epidemiological information.

Clonal relationships among naturally occurring nicotinamide-requiring Salmonella typhimurium

Salmonella typhimuriumstrains of biotype 25x have been shown in transductional cross experiments to be clonal in the Nad character. The ancestral bacterium, probably of biotype 25a, mutated to a requirement for nicotinamide and subsequently diversified in phage type and secondary biotype characters. Such a sequence of events indicates interconversion among phage types 6, 16, 46, 49, 73, 76 and 135. Strains in biotypes 1x, 9ix, 17x, 17dx, 19dx and 25hix yielded Nad+recombinants in interbiotype crosses, suggesting that each originated as an independent mutant line.

Colicin E2 production and release by Escherichia coli K12 and other Enterobacteriaceae

Previous work has shown that Escherichia coli K12 ColE2+ cells undergo a form of partial lysis and exhibit increases in lysophosphatidylethanolamine (lysoPE) and free fatty acid content due to activation of phospholipase A when induced to produce and release colicin E2. The increase in lysoPE content was assumed to be essential for efficient colicin release. These same characteristics are also presented by some natural ColE2+ isolates, and by other representatives of the Enterobacteriaceae after transformation with derivatives of a ColE2 plasmid. However, Salmonella typhimurium strains carrying ColE2 plasmids released colicin without partial lysis and without increasing their lysoPE content. A previously undetected minor phospholipid, which appeared in these and other strains only when they were induced to produce colicin, may be an important factor in colicin release. In ColE2+ E. coli K12, production of this new lipid was dependent on phospholipase A activation following expression of the ColE2 lysis gene. Some other ColE2+ strains did not respond to induction of colicin production in the same way as ColE2+ E. coli K12. These strains were less sensitive to inducer (mitomycin C) or unable to produce increased amounts of colicin in response to induction, or unable to degrade colicin once it was released. In general, the results suggest that colicin release occurs by the same or similar processes in the various strains tested, and support the continued use of E. coli K12 as the model strain for studying the mechanisms of colicin release.

Utilization of d-tartaric acid by Salmonella paratyphi B and Salmonella java: comparison of anaerobic plate test, lead acetate test and turbidity test

d-Tartrate dehydrase of Salmonella java is an oxygen-sensitive enzyme active in cultures incubated under the poorly aerated conditions of static culture but not in fully aerated shaken cultures nor on plates incubated aerobically. On plates of d-tartrate minimal agar incubated anaerobically the enzyme or the degradation products of d-tartrate are exported from d-tartrate-positive cells and are available to d-tartrate-negative bacteria. This may give misleading growth results when d-tartrate-positive and d-tartrate-negative strains are tested for growth on the same plate of d-tartrate minimal agar. The lead-acetate test terminated at 24 h, the 24 h turbidity test and the ability to grow on d-tartrate minimal agar within 48 h differentiated 53 S. paratyphi B strains that were negative in each of the three tests from 76 S. java that were positive in each of the tests. An intermediate group of eight strains utilized d-tartrate in Difco bacto-peptone water to give a positive lead acetate reaction at 2 days, were stimulated to a varying degree by d-tartrate in Oxoid peptone water within the same period of incubation and grew poorly on d-tartrate minimal agar. These latter strains may be deficient in a permease controlling uptake of d-tartrate or export of d-tartrate dehydrase. Inability to utilize d-tartrate is unlikely to be the single character accountable for the reputed enhanced pathogenicity of S. paratyphi B when compared with S. java. Indications for the existence of an enzyme, complementary to and mutually exclusive with d-tartrate dehydrase, that has a positive correlation with pathogenicity are discussed.

Competitive growth experiments with related pairs of tartrate-fermenting and tartrate-non-fermenting strains of Salmonella typhimurium: relevance to biotyping studies

For each of the isomers of tartaric acid, meso- or d- or l-, a pair of strains of Salmonella typhimurium was obtained, the one, a naturally occurring, non-fermenting strain and the other a spontaneous, tartrate-fermenting mutant derived from it. For each of the pairs of strains, competitive mixed cultures were grown from inocula of the tartrate-fermenting and tartrate-non-fermenting strains in peptone medium without or with the appropriate tartrate isomer. In each experiment, small numbers of tartrate-fermenting bacteria outgrew small or large numbers of tartrate-non-fermenting bacteria in 24 hours in tartrate-containing but not in tartrate-free peptone medium. The results of the experiments are discussed with reference to the choice of the definitive time of reading for tartrate-utilisation tests in the biotyping of S. typhimurium.

Further colicin types of Shigella sonnei detected with specific indicator strains

When 1420 isolates of Shigella sonnei recovered in Dundee, Scotland between 1971 and 1976 were examined with indicator strains of known immune status, four new colicin types, not previously described among the 26 types of Horák (8), were observed. The types were: 11 variant (colicins B, M), 4 variant (Ib, B, M), SH1 (E3) and SH3 (E5). Only type 4 variant strains were of epidemiological significance in the Dundee area.

Colicinogeny in Salmonella typhimurium

Colicin types, Ia, Ib, E1, E2, B with M, K, S4 and a new salmonellin-like colicin were found in 531 (11.8%) of 4481 wild-type cultures of Salmonella typhimurium. Colicin typing added little useful information to phage typing and biotyping in strain differentiation, mainly because the most common types, Ia and Ib, are controlled by conjugative plasmids. Evidence from the mixed-Col-/Col+ pattern of colicinogeny in circumscribed outbreaks caused by strains of known phage type and biotype suggested that some Col factors are readily acquired by S. typhimurium from other enteric species. When a Col factor of the nonconjugative type, e.g. ColE2, becomes established in strains of successful phage type/biotype line, it may be a useful additional marker character.

Biotypes of strains of Salmonella typhimurium of phage types 49, 204 and 193

Biotyping provided evidence of the phylogenetic relationships between strains of Salmonella typhimurium of phage types 49 and 204 and certain strains of phage type 193, which were interconvertible in phage types. All of 564 strains of phage types 49 and 204, 35 of which were chloramphenicol-resistant, were of biotype 26 whereas those of phage type 193 (91 strains) belonged to six different primary biotypes. Lines of descent are suggested for strains of phage type/biotype: 193/26a, 193/17g and 193/9f.

Transduction of inositol-fermenting ability demonstrating phylogenetic relationships among strains of Salmonella typhimurium

The production of Inl+recombinants was readily demonstrated in transductional crosses from Inl+donor strains to Inl−recipient strains from different biotypes and biogroups. None of numerous crosses between different pairs of strains from biotypes 25 and 26 and the biogroup FIRN (biotypes 29, 30, 31 and 32) gave Inl+recombinants suggesting that theinlmutation was present at the same intragenic site in all of these strains. Strains of the FIRN biogroup (Fim−Inl−Rha−Bxyl−) are thought to have descended by successiverhaandfimmutations from an ancestral bacterium of biotype 25 (Fim+Inl−Rha+Bxyl−). The sites of theinlmutations in other Inl−biotypes (9, 10, 27 and 25hi) were independent and each was different from that in strains from biotypes 25, 26 and FIRN.

Use of tartaric acid isomers and citric acid in the biotyping of Salmonella typhimurium

The colour-change and lead acetate tests for fermentation of d-, l- and m-tartaric acids and citric acid used in the Kristensen scheme for biotyping Salmonella typhimurium were found to be unreliable because, whatever the conditions of culture, they gave different results in replicate tests of the same strains. Many genotypically non-fermenting strains gave inconsistent reactions due to the emergence of fermenting mutant bacilli in some of their test cultures. No reliable test was found for the fermentation of citric acid.A ;turbidity' test was found to give consistent and reliable results with the three tartaric acid isomers. It demonstrated fermentation by the significantly greater amount of growth obtained in a 24 hr. culture in Oxoid peptone water with added isomer than in a control culture without isomer. Lewis & Stocker's (1971) plateinhibition test for fermentation of m-tartrate, which identifies m-tartrate-negative strains because m-tartrate inhibits their growth on citrate- or glycerol-containing minimal medium, was found to be as reliable as, and easier to read than, the turbidity test.Use of the turbidity test for d- and l-tartrates and the plate-inhibition test for m-tartrate in biotyping 1435 strains of S. typhimurium showed that many strains had previously been mistyped by the lead acetate test and distinguished 16 new biotypes in addition to the 22 biotypes already recognized.