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L R Ward

Publications and source records attributed to L R Ward.

At least 73 records · Page 4Linked to original sources
PubMed1994

Isolation and characterization of group-I isoallergens from Bermuda grass pollen.

Two isoallergens of Cyn d I were isolated using preparative isoelectric focussing, and were designated Cyn d Ia and b. These isoallergens differ in their pI, molecular weight (Cyn d Ia, 32 kD and Cyn d Ib, 31 kD) and their NH2-terminal sequence. Four monoclonal antibodies (Mabs) were produced using Cyn d Ia as antigen. These Mabs recognized both Cyn d Ia and b. One of the Mabs recognized four different pI forms of Cyn d I on 2D gels. The Mabs also recognized cross-reactive epitopes on proteins from eight other grasses including rye grass, timothy grass, Kentucky bluegrass and Johnson grass.

Allergens↗
PubMed1993

An outbreak of infection with Salmonella enteritidis phage type 4 associated with the use of raw shell eggs.

A community outbreak of Salmonella enteritidis phage type (PT) 4 infection, associated with eating food from a sandwich bar in Colchester, occurred in July 1991. One hundred and forty-four people were reported with food poisoning, of whom 132 met the clinical case definition. Three cohort studies of 92 people showed that illness was associated with the consumption of food containing mayonnaise. S. enteritidis PT4, indistinguishable by plasmid profile analysis, was isolated from stool samples from 83 people, food items including egg shells from the sandwich bar, and birds taken from the egg producing farm which supplied the eggs. This was the largest recorded outbreak of S. enteritidis PT4 infection in recent years associated with eggs produced in the United Kingdom. Existing advice on avoiding the use of raw eggs in uncooked dishes had not been followed. This outbreak highlights the importance of training in the implementation of this advice.

Adolescent↗
PubMed1993

A comparison of multiple drug resistance in salmonellas from humans and food animals in England and Wales, 1981 and 1990.

For Salmonella typhimurium from humans in England and Wales, the incidence of multiple resistance more than doubled over the 8-year period 1981-8 and, over the next 2 years, increased by a further 7%. From 1981 to 1988 both resistance and multiple resistance also increased significantly in S. virchow and although multiple resistance did not increase over the next 2 years, the overall incidence of resistance has continued to rise. In 1990 the majority of S. typhimurium from cattle were multiply-resistant and the occurrence of such resistance has quadrupled since 1981. Multiple resistance has also increased in S. typhimurium from pigs and, to a lesser extent, from poultry. In contrast, multiple resistance has remained uncommon in the poultry-associated serotype S. enteritidis. For S. virchow, multiple resistance was common in a phage type frequently associated with poultry meat imported from France. The continuing use of a range of different antimicrobials in calf husbandry has been an important factor in promoting the emergence of multiply-resistant strains of S. typhimurium in cattle. In contrast, multiple resistance has remained rare in those serotypes associated with poultry, where the use of such antimicrobials has been less intensive. It is hoped that recent recommendations discouraging, in veterinary medicine, the prophylactic use of antibiotics with cross resistance to those used in human medicine will result in a reduction in the occurrence of multiresistant strains in food animals and subsequently in humans.

Animals↗
PubMed1993

Insertion sequence IS200 can differentiate drug-resistant and drug-sensitive Salmonella typhi of Vi-phage types E1 and M1.

The type strains of Vi-phage types E1, M1 and A of Salmonella typhi, together with drug-resistant and drug-sensitive strains of phage types E1 and M1 isolated in 1992 from patients associated with India or Pakistan, and a drug-resistant strain of phage type A isolated in South Africa in 1991, were characterised with respect to the presence of plasmids conferring resistance to antimicrobial drugs and their chromosomal insertion sequence IS200 profiles. The three type strains, the drug-sensitive strains of Vi-phage types E1 and M1, and a strain of phage type M1 resistant to ampicillin and trimethoprim but not to chloramphenicol, did not contain plasmids. In contrast, for strains of phage types E1 and M1 resistant to chloramphenicol, ampicillin and trimethoprim, and for the drug-resistant strain of phage type A, the complete spectrum of resistance was encoded by high molecular mass plasmids belonging to the H1 incompatibility group. Characterisation of IS200 profiles demonstrated that at least 13 IS200 copies were distributed on the chromosome of all strains tested. Although the IS200 profiles of the type strains of Vi-phage types A, E1 and M1 were identical, it was possible to distinguish between drug-sensitive and drug-resistant strains of Vi-phage types E1 and M1 isolated from patients infected in India and Pakistan by this method. It was concluded that although IS200 typing is not as discriminatory as phage typing for the primary subdivision of S. typhi, it may be useful for certain epidemiological investigations and, in particular, for investigating the origins of strains with multiple drug resistance.

Bacteriophage Typing↗
PubMed1993

Characterization of Salmonella virchow phage types by plasmid profile and IS200 distribution.

The type strains of the 57 phage types of Salmonella virchow have been characterized by plasmid profile and by distribution of the insertion sequence IS200. Thirty-two strains carried plasmids and 21 profile types were identified; 17 strains were resistant to antimicrobial agents. In contrast only six of the type strains carried IS200 elements and three patterns were identified. Within Salm. virchow phage type 31, five of 10 wild-type isolates carried plasmids and two plasmid profiles were identified; in contrast, an IS200 element was identified in the genome of only one of these strains. It is concluded that for Salm. virchow, IS200 is unlikely to significantly extend the degree of discrimination achieved by phage typing which may be supplemented when appropriate by plasmid profile typing.

Animals↗
PubMed1993

Interrelationships between strains of Salmonella enteritidis belonging to phage types 4, 7, 7a, 8, 13, 13a, 23, 24 and 30.

Salmonella enteritidis strain P278849 expressed long-chain lipopolysaccharide (LPS, termed 'smooth'), carried plasmids of 38, 34 (pDEP 44, incompatibility group N, R-type AS), 2.0 and 1 MDa, and belonged to phage type (PT) 23. Introduction of pDEP 44 into a smooth strain of Salm. enteritidis PT 4 produced a smooth strain of Salm. enteritidis of PT 24. Transfer of this plasmid into a strain of PT 8 also resulted in formation of a smooth strain of Salm. enteritidis of PT 24. Moving pDEP 44 into strains of Salm. enteritidis of PTs 7 or 7a which did not express LPS (termed 'rough') resulted in rough strains of PT 23. In contrast, transfer of this plasmid into a smooth strain of Salm. enteritidis PT 7a resulted in a smooth strain of PT 23. Introduction of pDEP 44 into strains of Salm. enteritidis of PT 13 or PT 13a did not change the phage type, whereas transferring the plasmid into strains of PT 30 caused strains to become resistant to lysis by the typing phages and therefore untypable. The possibility of strains of Salm. enteritidis of PT 8 being the progenitors of strains of Salm. enteritidis of PT 24 must now be considered when investigating the epidemiology of Salm. enteritidis of PT 24 infections in areas where Salm. enteritidis PT 8 is common.

Animals↗
PubMed1992

Widespread occurrence of multiple drug-resistant Salmonella typhi in India.

Sixteen multiple drug resistant strains of Salmonella typhi belonging to Vi-phage types E1 (14) and O (2) and isolated in Southeast India in 1991 were characterized. All strains were resistant to chloramphenicol and the majority to trimethoprim and ampicillin. In all strains these resistances were encoded by plasmids of the H1 incompatibility group with molecular weights ranging from 110 to 120 megadaltons. Physicians in European countries should be aware that treatment may fail if patients with typhoid fever who have recently returned from the Indian sub-continent are given first-line treatment with chloramphenicol, trimethoprim or ampicillin. With the possible exception of young children, ciprofloxacin is currently the best choice for treatment of such patients.

Ampicillin Resistance↗
PubMed1992

Plasmid profiles demonstrate that an upsurge in Salmonella berta in humans in England and Wales is associated with imported poultry meat.

Sixteen plasmid profile types have been identified in drug-sensitive isolates of Salmonella berta isolated from humans and human food in England and Wales in the ten-year period 1981-1990. Since 1988 six profile types of epidemiological importance have caused infections in widely-separated geographical areas and of these, four types have been identified in S. berta isolated from chicken carcasses imported from Denmark. The findings suggest that imported Danish poultry has substantially contributed to a recent upsurge of S. berta in humans in England and Wales.

Animals↗
PubMed1990

Plasmid profile typing can be used to subdivide phage-type 49 of Salmonella typhimurium in outbreak investigations.

Plasmid profile typing has been used to subdivide phage-type 49 of Salmonella typhimurium, the most common phage type in humans in England and Wales since 1985. Twenty profile patterns have been identified in 350 strains examined. Four profile patterns have been identified in 143 isolates from patients infected in 33 epidemiologically unrelated incidents and two patterns have predominated, ST49:62 and ST49:62, 1. These patterns were also common amongst S. typhimurium phage-type 49 isolated from cattle and poultry; however ST49:62 was more common in bovines whereas ST49:62, 1 predominated in poultry. S. typhimurium phage-type 49 with a different profile pattern, ST49:62, 3, was responsible for a large outbreak in London in 1988 which was traced to mayonnaise made from eggs supplied by one producer. Plasmid profile typing can now be regarded as a method of supplementing phage typing in investigating outbreaks caused by this organism.

Animals↗
PubMed1990

Multiple drug resistance in salmonellae in England and Wales: a comparison between 1981 and 1988.

Each year from 1981 through to 1988 the most common serotypes isolated from man in England and Wales and identified at the Division of Enteric Pathogens were S typhimurium, S enteritidis, and S virchow. In 1981 these three serotypes accounted for 45%, 12%, and 7% of isolations. The remaining 35% comprised strains belonging to a further 188 different serotypes, none of which accounted for more than 1% of the total. In 1988 S typhimurium accounted for 24% of isolations, S enteritidis 57%, and S virchow 4%. The remaining 15% comprised strains of a further 184 serotypes. The resistances to the common antimicrobial drugs in non-typhoidal salmonellas isolated in England and Wales in 1981 and 1988 were reported with particular reference to resistance to four or more antimicrobial drugs (multiple resistance). For S typhimurium the overall percentage of resistant strains varied little, but multiple resistance more than doubled from 5% to 12%; in S enteritidis the incidence remained the same. In S virchow the percentages of strains resistant to all the antimicrobial drugs and in particular, to chloramphenicol, streptomycin, trimethoprim and furazolidone, rose from 0.2% to 10.4%. Salmonella enteritis in man is usually a self limiting disease and antimicrobial treatment is seldom required; but should spread beyond the intestine occur, effective antimicrobial treatment is essential. Under these circumstances a knowledge of the likelihood of resistances to commonly available drugs could be of considerable value to the clinician.

Anti-Bacterial Agents↗
PubMed1989

Salmonella enteritidis phage type 4 infection of broiler chickens: a hazard to public health.

The pericardial fluids and contents of caeca and spleens from 81 broiler chickens that had been condemmed at processing factories because of macroscopic pericarditis were examined for Salmonella species. 47 (58%) of these chickens yielded S enteritidis phage type (PT) 4. Viable counts of the organism in fluids from 6 of the most severely affected hearts ranged from 10(4) to 10(7) colony-forming units/ml. S enteridis PT4 was also isolated from 8 of 20 fresh chilled chickens on retail sale. No other serotype of Salmonella or phage type of S enteritidis was cultured either from the chickens with pericarditis or from the fresh chilled chicken.

Animals↗
PubMed1989

Conversion of Salmonella enteritidis phage type 4 to phage type 7 involves loss of lipopolysaccharide with concomitant loss of virulence.

Three strains of Salmonella enteritidis phage type 4 (PT4) and 33 strains of S. enteritidis phage type 7 (PT7) were examined for the ability to produce lipopolysaccharide (LPS) and for plasmid carriage. The LPS of all strains of PT4 gave a typical 'ladder' pattern by SDS-PAGE and silver staining, and on serotyping these strains were shown to express the O-antigens 9, 12. In contrast, strains of PT7 did not express long-chain LPS and were autoagglutinable. All strains of PT4 and the majority of strains of PT7 carried a single plasmid of 38 MDa, indistinguishable when characterised by restriction endonuclease fragmentation analysis. Epidemiological and experimental observations have demonstrated a relationship between strains of S. enteritidis PT4 and PT7, and our results, using mice, show that the loss of ability of strains of PT4 to snythesise LPS is responsible for the conversion of highly virulent strains of PT4 to avirulent strains of PT7. From epidemiological data of human infections in England and Wales, we suggest that strains of S. enteritidis PT7 may be less virulent for humans.

Animals↗
PubMed1989

Large outbreak of food poisoning caused by Salmonella typhimurium definitive type 49 in mayonnaise.

An investigation was conducted to determine the vehicle of infection of an outbreak of food poisoning in a large metropolitan building early in 1988. A questionnaire was distributed to 700 people who had eaten in the building during the week of the outbreak, and attack rates for specific food were calculated. Food and stool samples, environmental samples, and eggs and environmental swabs from the egg suppliers were examined microbiologically. Altogether 474 questionnaires were returned, 120 people reporting gastrointestinal illness. The illness was significantly associated with foods containing mayonnaise. Salmonella typhimurium definitive type 49 was isolated from 76 of the 84 stool samples containing salmonella and from five of the eight samples taken from the chicken house of the main egg supplier. Mayonnaise was probably the vehicle of infection, which was caused by S typhimurium definitive type 49.

Adult↗