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L R Ward

Publications and source records attributed to L R Ward.

At least 91 records · Page 5Linked to original sources
PubMed1989

Subdivision of Salmonella enteritidis phage types by plasmid profile typing.

Differentiation of Salmonella enteritidis by plasmid profile typing has been compared to differentiation by phage typing. Examination of the type strains of the 27 S. enteritidis phage types showed that only 11 profile patterns could be identified. Moreover, two profile patterns were found in 15 of the type strains, including those of the two most common phage types in Britain, types 4 and 8. On this basis, plasmid profile typing is not as sensitive as phage typing for the primary subdivision of S. enteritidis. When differentiation of 534 strains of the 27 phage types was attempted using plasmid profiles, variation in pattern suitable for epidemiological subdivision was found in 13 phage types and there were 9 profile patterns in strains of phage type 4. Plasmid profile typing can, therefore, be regarded as an effective adjunct to phage typing for the subdivision of S. enteritidis.

Bacteriophage Typing↗
PubMed1989

Acquisition of a drug resistance plasmid converts Salmonella enteritidis phage type 4 to phage type 24.

Salmonella enteritidis accounted for 55% of the 27,478 salmonellae isolated from humans in England and Wales during 1988. Within this serotype phage type 24 has increased from 24 isolations in 1987 to 201 in 1988. The high frequency of drug resistance in this phage type has been shown to be due to the presence of plasmids belonging to Inc N and coding for resistance to a range of antimicrobial drugs among which resistance to ampicillin, streptomycin, tetracycline (AST) and T predominate. These plasmids are phage-type determining and convert strains of phage type 4 to phage type 24.

Atlantic Islands↗
PubMed1987

Does chloramphenicol remain the drug of choice for typhoid?

Of 2356 strains of Salmonella typhi isolated in Britain in the 8-year period 1978-85, 2345 (99.53%) were sensitive to all antibiotics tested and 11 (0.47%) were chloramphenicol-resistant; chloramphenicol resistance was plasmid-mediated in 6 strains. It is concluded that chloramphenicol remains a satisfactory first-line choice of drug for typhoid fever in Britain.

Chloramphenicol↗
PubMed1987

A phage-typing scheme for Salmonella enteritidis.

For many years phage typing has proved invaluable in epidemiological studies on Salmonella typhi, S. paratyphi A and B, S. typhimurium and a few other serotypes. A phage-typing scheme for S. enteritidis is described. This scheme to date differentiates 27 types using 10 typing phages.

Animals↗
PubMed1986

Characterization of plasmids conferring resistance to gentamicin and apramycin in strains of Salmonella typhimurium phage type 204c isolated in Britain.

In Salmonella typhimurium phage type 204c isolated in Britain, gentamicin resistance is specified by plasmids of the I1 compatibility group which also confer resistance to apramycin. These plasmids have been subdivided into three types within the I1 group on the basis of their antibiotic resistance specificity, their ability to produce colicin Ib and their restriction enzyme digest fragmentation patterns. All three have been identified in strains from cattle, but as yet only two types have been found in strains from humans. It is suggested that the use of apramycin in animal husbandry is responsible for the appearance of gentamicin resistance in multiresistant strains of phage type 204c, a phage type already epidemic in bovine animals and with an increasing incidence in humans.

Acetyltransferases↗
PubMed1986

R plasmids in Salmonella typhimurium in the United Kingdom.

In the United Kingdom, R plasmids are common in bovine-associated phage types of Salmonella typhimurium and in particular in strains of phage type 204c (DT204c); all strains of this type carry at least three R plasmids. Gentamicin resistance appeared in DT204c in 1983 and plasmids conferring resistance to gentamicin also code for resistance to apramycin. Three types of apramycin-gentamicin resistance plasmid have been identified.

Humans↗
PubMed1986

Molecular techniques in the study of Salmonella typhi in epidemiologic studies in endemic areas: comparison with Vi phage typing.

We examined 141 Salmonella typhi strains of known phage type isolated during ongoing epidemiologic studies in Santiago, Chile, and Lima, Peru. Plasmids were present in 12 (17%) of 70 S. typhi isolates from Santiago and 5 (7%) of 71 isolates from Lima; these plasmids were not associated with antimicrobial resistance. Identical 21 kilobase (kb) plasmids (as defined by restriction endonuclease digest pattern) were present in 13 of the 17 plasmid-containing isolates. Virtually identical digest patterns were identified when chromosomal DNA of selected strains from Santiago, Lima, and the United States was extracted and then digested with restriction endonucleases. The similarities among plasmids and chromosomal digest patterns emphasize the homogeneity and possible clonal origin of S. typhi isolates; these data also suggest that there is only a limited role for plasmid and chromosomal analysis as a substitute for phage typing in epidemiologic studies.

Bacteriophage Typing↗
PubMed1986

An international point source outbreak of typhoid fever: a European collaborative investigation.

A point source outbreak of Salmonella typhi, degraded Vi-strain 22, affecting 32 British visitors to Kos, Greece, in 1983 was attributed by a case-control study to the consumption of a salad at one hotel. This represents the first major outbreak of typhoid fever in which a salad has been identified as the vehicle. The source of the infection was probably a carrier in the hotel staff. The investigation demonstrates the importance of national surveillance, international cooperation, and epidemiological methods in the investigation and control of major outbreaks of infection.

Adolescent↗
PubMed1985

Increasing incidence of resistance to gentamicin and related aminoglycosides in Salmonella typhimurium phage type 204c in England, Wales and Scotland.

Phage type 204c of Salmonella typhimurium (DT 204c) appeared in bovine animals in 1979. It is now the predominant type in cattle in England, Wales and Scotland and ranks in the 10 most common phage types in humans. All strains of DT 204c have been resistant to at least four antimicrobial drugs. In 1979 and 1980 the most common resistance pattern was that of chloramphenicol, streptomycin, sulphonamides, tetracyclines and trimethoprim (CSSuTTm) but since 1981 strains with additional resistance to ampicillin and neomycin-kanamycin (AK) have predominated. Strains resistant to furazolidone (Fu) have caused sporadic outbreaks. Gentamicin resistance (G) appeared in DT 204c in 1983 and gentamicin-resistant strains are increasing in incidence. With the exception of resistance to furazolidone, drug resistance in DT 204c has been plasmid-mediated. Characterisation of gentamicin resistance plasmids in DT 204c of R-type ACGKSSuTTm has demonstrated the existence of three distinct lines, two of which have been found exclusively in cattle and one in cattle and humans. The misguided and often inappropriate use of antimicrobial drugs in calves has contributed to the appearance of multiresistant strains of DT 204c and positive measures to limit range and levels of antimicrobials available to feed manufacturers may be necessary.

Aminoglycosides↗
PubMed1984

Drug resistance in Shigella dysenteriae, S flexneri and S boydii in England and Wales: increasing incidence of resistance to trimethoprim.

A total of 2753 strains of shigella belonging to subgroups A, B, and C that were isolated from patients in England and Wales during the period from 1979 to mid-1983 were studied. Of these, 1690 (61%) were from patients recently returned from abroad or in contact with recent travellers, and 760 (45%) of these affected travellers from the Indian subcontinent. The number of strains resistant to sulphonamides and streptomycin remained at a high level throughout (average 76% and 72% respectively). Resistance to tetracyclines, ampicillin, and chloramphenicol rose, reaching 63%, 51%, and 48%, respectively, in 1982. Strains resistant to trimethoprim were seen in substantial numbers for the first time and increased from 1.3% of all strains in 1979 to 9.9% in 1982 and 16.8% in the first half of 1983. The proportion of patients with recent foreign contact was notably smaller among those with strains resistant to trimethoprim than among those with strains sensitive to trimethoprim. The increase in resistance to trimethoprim might partly result from the use in Britain of compounds containing trimethoprim for the treatment of shigellosis.

Ampicillin↗
PubMed1983

Drug resistance among Escherichia coli strains isolated from cerebrospinal fluid.

One hundred and thirty-one strains of Escherichia coli isolated from the cerebrospinal fluid of patients in the United Kingdom were tested for resistance to 13 antimicrobial drugs. Sixty-four strains (49%) were resistant to one or more drugs and 44 (34%) were resistant to three or more drugs. Resistance to ampicillin, sulphonamides, streptomycin and tetracycline occurred most frequently.

Anti-Bacterial Agents↗
PubMed1983

A hospital outbreak of multiresistant Salmonella typhimurium belonging to phage type 193.

An outbreak of nosocomial infection was caused by strains of Salmonella typhimurium phage type 193 that were resistant to ampicillin, chloramphenicol, neomycin-kanamycin, streptomycin, spectinomycin, sulfonamides, tetracyclines, trimethoprim, and nalidixic acid. Resistances to drugs other than nalidixic acid were specified by plasmids, and, on the basis of phage typing and plasmid characterization studies, the multiresistant phage type 193 strains were determined to be clonal. In a two-year period, 488 patients infected with these bacteria were identified. An investigation in a pediatric surgical ward, where the outbreak was particularly severe, showed that patients exposed to antibiotics were more likely to be colonized with the epidemic strain and that young debilitated patients were more liable to show clinical signs of infection. Epidemiologic studies suggested that cross infection via the hands of the ward staff was the likely means of propagation of the epidemic.

Anti-Bacterial Agents↗
PubMed1982

Drug resistance among infantile enteropathogenic Escherichia coli strains isolated in the United Kingdom.

Two hundred and thirty-two strains of Escherichia coli belonging to infantile enteropathogenic serotypes isolated in the United Kingdom during 1980 and 1981 were tested for resistance to 10 antimicrobial drugs. Resistance to one or more drugs was found in 134 (57.8%) of the strains, with resistance to sulphonamides, streptomycin, tetracycline, and ampicillin occurring most commonly. Resistance was transferable in 65 out of 104 resistant strains. These findings are a cause for concern because they indicate that the choice of treatment for severe illness is limited and suggest that a large pool of drug-resistant organisms exists in the community.

Child, Preschool↗
PubMed1982

Characterization of resistance plasmids and carried phages in an epidemic clone of multi-resistant Salmonella typhimurium in India.

Hospital outbreaks of severe gastroenteritis caused by multi-resistant Salmonella typhimurium have occurred in a number of cities throughout India since 1977. The strains involved belong to phage types 66 or 122, or are untypable; the latter are derived from types 66 or 122 by acquisition of one or more of a number of temperate bacteriophages. Types 66 and 122 are closely related and react with the same phages of the S. typhimurium typing scheme. A plasmid belonging to compatibility group F1me encoding resistance to ampicillin, chloramphenicol, kanamycin, streptomycin, sulphonamides, spectinomycin, tetracyclines, gentamicin and trimethoprim (R-type ACKSSuSpTGTm) is present in all of the multi-resistant strains. Several other plasmids have been identified including an SSu resistance determinant, a group I2 transfer factor and an R factor coding for resistance to kanamycin, streptomycin and sulphonamides which is compatible with plasmids of all the standard compatibility groups. These plasmids are only present in a proportion of the strains examined. Examination of strains from other sources has identified a paediatric hospital outbreak in Saudi Arabia and a number of sporadic infections in Great Britain which have been caused by the same organisms. These studies show that, despite differences in phage type and plasmid content, this group of strains belongs to a single clone which has become widespread in India with some extension to other countries.

Bacteriophage Typing↗