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F A Clifton-Hadley

Publications and source records attributed to F A Clifton-Hadley.

At least 19 recordsLinked to original sources
PubMed2006

Longitudinal farm study of extended-spectrum beta-lactamase-mediated resistance.

Extended-spectrum beta-lactamase (ESBL)-mediated resistance is of considerable importance in human medicine. Recently, such enzymes have been reported in bacteria from animals. We describe a longitudinal study of a dairy farm suffering calf scour with high mortality rates. In November 2004, two Escherichia coli isolates with resistance to a wide range of beta-lactams (including amoxicillin-clavulanate and cefotaxime) were isolated from scouring calves. Testing by PCR and sequence analysis confirmed the isolates as being both bla(CTX-M14/17) and bla(TEM-35) ((IRT-4)) positive. They had indistinguishable plasmid and pulsed-field gel electrophoresis (PFGE) profiles. Transferability studies demonstrated that bla(CTX-M) was located on a conjugative 65-MDa IncK plasmid. Following a farm visit in December 2004, 31/48 calves and 2/60 cows were positive for E. coli with bla(CTX-M). Also, 5/48 calf and 28/60 cow samples yielded bla(CTX)- and bla(TEM)-negative E. coli isolates that were resistant to cefotaxime, and sequence analysis confirmed that these presented mutations in the promoter region of the chromosomal ampC gene. Fingerprinting showed 11 different PFGE types (seven in bla(CTX-M)-positive isolates). Six different PFGE clones conjugated the same bla(CTX-M)-positive IncK plasmid. One clone carried a different-sized, bla(CTX-M)-positive, transformable plasmid. This is the first report of bla(CTX-M) from livestock in the United Kingdom, and this report demonstrates the complexity of ESBL epidemiology. Results indicate that horizontal plasmid transfer between strains as well as horizontal gene transfer between plasmids have contributed to the spread of resistance. We have also shown that some clones can persist for months, suggesting that clonal spread also contributes to the perpetuation of resistance.

Animals↗
PubMed2005

Resistance to oxyiminocephalosporins mediated by blaTEM-52 genes in Salmonella typhimurium from humans in England and Wales.

The emergence of antimicrobial resistance among Salmonella is a matter of great public health concern, more so in the case of extended-spectrum cephalosporins, since these antimicrobials are normally regarded as the drugs of choice for complicated cases of infection. This study was designed to determine the occurrence of resistance mediated by the presence of extended-spectrum beta-lactamases (ESBL) enzymes belonging to the TEM family. Only two isolates were detected after analysis of the 278,308 Salmonella isolates from the last 10 years. In both cases, the gene involved was a bla (TEM-52)-like, and infections were linked with foreign travel. ESBL-TEM enzymes remain very rare in Salmonella in England and Wales, and no domestic cases have been detected to date.

Cephalosporin Resistance↗
PubMed2005

Detection of multiple cephalosporin-resistant Escherichia coli from a cattle fecal sample in Great Britain.

We describe the isolation of multiple cephalosporin-resistant Escherichia coli from cattle feces collected from animals at slaughter in Great Britain. Six E. coli strains were isolated with distinct XbaI pulsed-field gel electrophoresis (PFGE) profiles and different mechanisms of cephalosporin resistance from a single fecal sample. Two of these strains were found to contain conjugative plasmids conferring resistance to extended-spectrum cephalosporins that were indistinguishable from each other by restriction endonuclease digestion. Sequence analysis of the plasmid-encoded ampC showed that they were identical to bla(CMY-2), previously described in multiple-drug-resistant Salmonella and E. coli from animals in other parts of the world. DNA sequence analysis of the chromosomal ampC promoter regions for three cephalosporin-resistant strains lacking CMY-2 was determined. Several mutations were detected in the isolates tested including changes at positions -42 and -32, which are known to increase promoter strength. This report represents the first isolation of E. coli containing bla(CMY-2) from cattle in Great Britain, and, also to our knowledge, the first demonstration of multiple cephalosporin-resistant strains in a single animal.

Animals↗
PubMed2005

Farm disinfectants select for cyclohexane resistance, a marker of multiple antibiotic resistance, in Escherichia coli.

AIMS: The aim of this study was to determine if three classes of farm disinfectants were able to select for ciprofloxacin or cyclohexane tolerant [indicative of a multiple antibiotic resistance (MAR) phenotype] Escherichia coli and if cyclohexane-tolerant E. coli could be isolated from farms. METHODS AND RESULTS: Chicken slurry containing ca 1 : 99 ratio ciprofloxacin resistant : susceptible E. coli (10 different resistant strains examined) was treated for 24 h with each of the disinfectants and examined for survival of resistant : susceptible strains. Ciprofloxacin-sensitive (n=5) and -resistant (n=5) E. coli were grown with sublethal concentrations of the disinfectants and then plated to agar containing ciprofloxacin or overlaid with cyclohexane. Escherichia coli (n=389) isolated from farms were tested for cyclohexane tolerance. Minimum inhibitory concentrations (MIC) were determined against representative isolates and mutants. The disinfectants did not select for the ciprofloxacin-resistant E. coli in poultry slurry but following growth with each of the three disinfectants, higher numbers (P < or = 0.023) of cyclohexane-tolerant E. coli were isolated and these had a MAR phenotype. Of the 389 farm E. coli tested, only one was cyclohexane tolerant. CONCLUSIONS: It is possible that in a farm environment, E. coli could be exposed to similar concentrations of the disinfectants that are selected for MAR type organisms under these laboratory conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Data from this study suggest that cyclohexane-resistant E. coli are not common on farms, but in view of the ease of isolating them in the laboratory with farm disinfectants, further investigations on farms are warranted.

Agrochemicals↗
PubMed2005

bla(CTX-M) genes in clinical Salmonella isolates recovered from humans in England and Wales from 1992 to 2003.

Cefotaximases (CTX-M) are a rapidly growing class A beta-lactamase family that has been found among a wide range of clinical bacteria. One hundred and six isolates were selected from 278,308 Salmonella isolates based on resistance to ampicillin and cephalosporins and subjected to further characterization. Fourteen isolates were bla(CTX-M) PCR positive, and cefotaxime MICs for these isolates were > or = 16 mg/liter. Furthermore, sequence analysis revealed the presence of type CTX-M9, -15, or -17 to -18. All 14 isolates presented different PFGE restriction profiles, although six Salmonella enterica serotype Virchow isolates formed a tight cluster. The bla(CTX-M) genetic determinants were present in transferable plasmids of approximately 63, 105, and >148 kb. Plasmid restriction analysis showed that both horizontal transfer of similar plasmids among different clones and transfer of genes between different plasmids were likely mechanisms involved in the spread of bla(CTX-M) genes. We have found that CTX-M enzymes have emerged in community-acquired infections both linked to foreign travel and domestically acquired. This is the first report of a CTX-M enzyme in Salmonella in the United Kingdom. Also, it represents the first report of a bla(CTX-M) gene in Salmonella enterica serotype Stanley and a bla(CTX-M-15) gene in Salmonella enterica serotypes Anatum, Enteritidis, and Typhimurium.

Anti-Bacterial Agents↗
PubMed2005

Characterization of AmpC-mediated resistance in clinical Salmonella isolates recovered from humans during the period 1992 to 2003 in England and Wales.

The increase in AmpC-mediated resistance in salmonellae constitutes a serious public health concern, since these enzymes confer resistance to a wide range of beta-lactams. One hundred six isolates were selected from 278,308 Salmonella isolates based on resistance to ampicillin and cephalosporins and were subjected to further characterization. Nine isolates had a cefoxitin inhibition diameter < or = 17 mm and were proven to be AmpC positive by multiplex PCR. Sequence analysis revealed the presence of bla(DHA-1), bla(CMY-2), and bla(CMY-4) genes. All nine isolates presented different pulsed-field gel electrophoresis restriction profiles. The AmpC genetic determinants were present in transferable plasmids of around 11, 42, 70, 98, and 99 MDa. A combination of size and restriction fragment length polymorphism (RFLP) analysis showed that all the bla(CMY) plasmids investigated in our study were different, which suggests that bla(CMY) may be located in different plasmid environments. Some United Kingdom isolates linked to foreign travel showed RFLP plasmid patterns consistent with plasmids previously seen in the United States, which suggests that bla(CMY-2) has also been disseminated through plasmid transfer. The fact that two of the domestically acquired United Kingdom isolates presented previously unseen RFLP plasmid patterns could indicate that these strains have followed routes different from those prevalent in North America or other parts of the world. This study represents the first report of bla(CMY) genes in Salmonella isolates in the United Kingdom and the first report of CMY-4 in Salmonella enterica serotype Senftenberg worldwide.

Bacterial Proteins↗
PubMed2003

Molecular fingerprinting evidence of the contribution of wildlife vectors in the maintenance of Salmonella Enteritidis infection in layer farms.

AIMS: To provide molecular fingerprinting evidence of the contribution of wildlife vectors in the on-farm epidemiology of Salmonella Enteritidis infections. METHODS AND RESULTS: Salmonella Enteritidis strains were isolated from wildlife and from farm environment samples collected in 10 egg layer farms. Isolates were typed using plasmid profiling, XbaI-pulsed field gel electrophoresis and PstI-SphI ribotyping. In all 10 farms we were able to identify the same S. Enteritidis clones in wildlife vectors and farm environment. On several occasions the same clones were found before and after cleansing and disinfecting the farm premises. Also in some instances the same clones were present in mice samples, egg contents and spent hens. CONCLUSIONS: Definitive molecular evidence for the involvement of several wildlife species (mice, rats, flies, litter beetles and foxes) in the maintenance of S. Enteritidis infection on farms has been presented. Failures in biosecurity seriously compromise the control of this pathogen on laying farms. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper reports on the use of molecular tools for the study of the epidemiology of S. Enteritidis. It gives useful information to be considered in control programmes for this organism on poultry farms.

Animals↗
PubMed2002

A laboratory study of an inactivated bivalent iron restricted Salmonella enterica serovars Enteritidis and Typhimurium dual vaccine against Typhimurium challenge in chickens.

A commercial inactivated iron restricted Salmonella Typhimurium and Salmonella Enteritidis vaccine was used to vaccinate chicks at 1 day and again at 4 weeks of age, with challenge by a high and a low dose of S. Typhimurium given either orally or by contact with seeder birds inoculated orally with a high dose of S. Typhimurium. In all three challenge regimes, the shedding of challenge strain was reduced significantly (p < 0.05) in vaccinated birds compared with unvaccinated controls. Vaccination reduced colonisation of internal organs after challenge by contact seeder birds. However, no effect of vaccination upon colonisation of internal organs after either high or low oral challenge was apparent. In conclusion, the data indicate that the vaccine should be a useful tool in the control of S. Typhimurium infection in chickens.

Animals↗
PubMed2002

Salmonella enterica serotype Enteritidis phage types 4, 7, 6, 8, 13a, 29 and 34: a comparative analysis of genomic fingerprints from geographically distant isolates.

AIMS: To evaluate genetic heterogeneity in the most common phage types of Salmonella enterica serovar Enteritidis. METHODS AND RESULTS: A total of 233 isolates of Salm. Enteritidis from England, Northern Ireland, Spain, Hong Kong and the USA belonging to phage types (PT) 4 (n=88), PT7 (n=12), PT6 (n=72), PT8 (n=14), PT13a (n=29), PT29 (n=14) and PT34 (n=4) were characterized by PstI-SphI (PS) ribotyping and pulsed-field gel electrophoresis after digestion of DNA with XbaI. PS ribotyping differentiated the isolates into 53 different PS types and PFGE showed 14 different macrorestriction profiles; with the combination of both methods, 73 combined types were identified. Some of these clones appeared to be present within several countries. Movement of foodstuffs, animals or people may have been involved in the spread of these strains. On the other hand, some clones were only found in specific locations. CONCLUSIONS: Several well defined clonal lines seem to co-exist within the different phage types included in this study, and a combined typing approach may constitute a useful tool for epidemiological investigations. Clustering analysis of ribotypes and PFGE types agree with previous studies and suggest that phage types that share receptor binding properties can be distinguished as two families: the PT4 family including PT7 and PT6, and the PT8 family including PT13a. The other phage types are difficult to place in a family unless the geographical site of isolation is known. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper reports on an extensive assessment of the use of molecular tools for the study of the epidemiology of the enteric pathogen Salm. Enteritidis. It also gives new information regarding relationships among some common phage types.

DNA Fingerprinting↗
PubMed2002

Investigation of the genetic diversity among isolates of Salmonella enterica serovar Dublin from animals and humans from England, Wales and Ireland.

AIMS: To assess the degree of genetic diversity among animal Salmonella Dublin UK isolates, and to compare it with the genetic diversity found among human isolates from the same time period. METHODS AND RESULTS: One hundred isolates (50 human and 50 animal) were typed using plasmid profiling, XbaI-pulsed field gel electrophoresis (PFGE) and PstI-SphI ribotyping. Antimicrobial resistance data to 16 antibiotics was presented, and the presence of class-I integrons was investigated by real-time PCR. Seven different plasmid profiles, 19 ribotypes and 21 PFGE types were detected. A combination of the three methods allowed clear differentiation of 43 clones or strains. Eighteen isolates were resistant to at least one antimicrobial; five of them were multi-resistant and of these, only three presented class I integrons. CONCLUSIONS: Ribotyping data suggest the existence of at least three very different clonal lines; the same distribution in well-defined groups was not evident from the PFGE data. The existence of a variety of clones in both animals and humans has been demonstrated. A few prevalent clones seem to be widely disseminated among different animal species and show a diverse geographical and temporal distribution. The same clones were found in animals and humans, which may infer that both farm and pet animals may act as potential vehicles of infection for humans. Some other clones seem to be less widely distributed. Clustering analysis of genomic fingerprints of Salmonella Dublin and Salm. Enteritidis isolates confirms the existence of a close phylogenetic relationship between both serotypes. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper describes the utility of a multiple genetic typing approach for Salm. Dublin. It gives useful information on clonal diversity among human and animal isolates.

Animals↗
PubMed2001

Molecular typing of Salmonella serotypes prevalent in animals in England: assessment of methodology.

Salmonella enterica serotypes Derby, Mbandaka, Montevideo, Livingstone, and Senftenberg were among the 10 most prevalent serotypes isolated from farm animals in England and Wales in 1999. These serotypes are of potential zoonotic relevance; however, there is currently no "gold standard" fingerprinting method for them. A collection of isolates representing the former serotypes and serotype Gold Coast were analyzed using plasmid profiling, pulsed-field gel electrophoresis (PFGE), and ribotyping. The success of the molecular methods in identifying DNA polymorphisms was different for each serotype. Plasmid profiling was particularly useful for serotype Derby isolates, and it also provided a good level of discrimination for serotype Senftenberg. For most serotypes, we observed a number of nontypeable plasmid-free strains, which represents a limitation of this technique. Fingerprinting of genomic DNA by ribotyping and PFGE produced a significant variation in results, depending on the serotype of the strain. Both PstI/SphI ribotyping and XbaI-PFGE provided a similar degree of strain differentiation for serotype Derby and serotype Senftenberg, only marginally lower than that achieved by plasmid profiling. Ribotyping was less sensitive than PFGE when applied to serotype Mbandaka or serotype Montevideo. Serotype Gold Coast isolates were found to be nontypeable by XbaI-PFGE, and a significant proportion of them were found to be plasmid free. A similar situation applies to a number of serotype Livingstone isolates which were nontypeable by plasmid profiling and/or PFGE. In summary, the serotype of the isolates has a considerable influence in deciding the best typing strategy; a single method cannot be relied upon for discriminating between strains, and a combination of typing methods allows further discrimination.

Animals↗
PubMed1984

Monitoring herds for Streptococcus suis type 2 by sampling tonsils of slaughter pigs.

Heads were removed soon after slaughter from the dressed carcases of 155 pigs belonging to 12 herds with a history of streptococcal meningitis and from 180 pigs from four herds believed to be free from this disease. Deep scrapings from both tonsils were sown on two selective media. Streptococcus suis type 2 was detected in a proportion of pigs from the 12 herds with a history of the disease, including three herds in which no cases were noted during the year this study was made. Pigs in six of these herds had received therapeutic levels of certain antibiotics in their feed as growers. The confirmed detectable tonsillar carrier rates varied between these 12 herds from 20 to 90 per cent and between batches of heads from one herd from 0 to 100 per cent. Carrier rates could not be correlated with disease levels, herd size or husbandry system. S suis type 2 was also detected in pigs from two herds thought to be free of the disease, at rates of 20 and 1.5 per cent.

Animal Husbandry↗
PubMed1984

Factors affecting the survival of Streptococcus suis type 2.

The survival of Streptococcus suis type 2 was assessed in experimentally inoculated faeces and dust stored at 0, 9 and 22 to 25 degrees C. The organism survived in faeces for 104 days at 0 degrees C, up to 10 days at 9 degrees C and up to eight days at 22 to 25 degrees C. It survived in dust for up to 54 days at 0 degrees C and up to 25 days at 9 degrees C but could not be isolated from dust stored at room temperature for 24 hours. The organism survived at 4 degrees C in nutrient medium for up to nine months but in distilled water for only one to two weeks. At 50 degrees C it survived in water or broth for up to two hours but at 60 degrees C it only survived for 10 minutes. The organism was rapidly inactivated by disinfectants and cleansers, commonly used on farms and in laboratories, at concentrations less than those recommended for use by the manufacturers.

Animals↗