Salmonella Typhimurium in livestock in Great Britain - trends observed over a 32-year period.

In this retrospective study, we describe and analyse Salmonella data from four livestock species in Great Britain between 1983 and 2014, focusing on Salmonella Typhimurium. A total of 96 044 Salmonella isolates were obtained during the study period. S. Typhimurium was the predominant serovar isolated from cattle and pigs and represented 40.7% (18 455/45 336) and 58.3% (4495/7709) of isolates from these species respectively, while it only accounted for 6.7% (2114/31 492) of chicken isolates and 8.1% (926/11 507) of turkey isolates. Over the study period, DT104 was the most common phage type in all four species; however, DT104 peaked in occurrence between 1995 and 1999, but is currently rare. Monophasic strains of S. Typhimurium represented less than 3% of all Salmonella isolates in cattle and chickens in 2014, but accounted for 10.4% of all turkey isolates and 39.0% of all pig isolates in the same year. Salmonella isolates were tested for their in vitro susceptibility to 16 antimicrobials. Antimicrobial resistance of S. Typhimurium isolates is largely influenced by the dominance of specific phage types at a certain time, which are commonly associated with particular resistance patterns. Changes in resistance patterns over time were analysed and compared between species.

Wild birds carry similar Salmonella enterica serovar Typhimurium strains to those found in domestic animals and livestock.

The objective of this study was to investigate the hypothesis that some sporadic Salmonella infections in domesticated animals may be associated with Salmonella infections originating from garden birds. Phage type and antimicrobial resistance details of isolates of S. Typhimurium obtained from wild birds were comparable with those from S. Typhimurium infections from domesticated animals or livestock between 2002 and 2010. A small panel of S. Typhimurium isolates (n=37) were characterised by multilocus variable number of tandem repeats analysis (MLVA), pulsed field gel electrophoresis (PFGE) and phage type. The MLVA-PFGE data clustered the strains according to phage type (DT40 or DT56). Within each group there were strains from wild birds and domesticated animals or livestock with MLVA profiles having up to 100% similarity. The results from this study therefore lend support to the hypothesis that Salmonella infections in domesticated animals could be caused by infections carried by wild birds.

Treatment of anaemia after joint replacement. A double-blind, randomised, controlled trial of ferrous sulphate versus placebo.

After total hip and knee replacement arthroplasty, patients may become anaemic and may be prescribed oral iron. There is, however, no published evidence that this is of benefit when used postoperatively. We treated 72 patients who were anaemic after primary total hip and knee arthroplasty by randomly allocating them to receive six weeks of either oral ferrous sulphate (35 patients) or a placebo (37 patients). Both groups of patients were similar in all aspects except for the treatment given. There was no statistically significant difference in the change of haemoglobin levels between the two groups. We therefore believe that the prescription of iron to all anaemic patients post-operatively should be avoided. The level of serum ferritin should be monitored at preoperative assessment.

A comparison of antimicrobial susceptibilities in nontyphoidal salmonellas from humans and food animals in England and Wales in 2000.

A joint study by the Public Health Laboratory Service and the Veterinary Laboratories Agency of resistance to antimicrobials in isolates of Salmonella enterica serotypes Enteritidis, Typhimurium, Hadar, and Virchow from humans and food-producing animals in England and Wales in 2000 has demonstrated that resistance was most common in Typhimurium, particularly in strains of definitive phage type (DT) 104. However resistance was also common in other phage types, particularly DTs 193 and 208 and phage type U302. Multiresistant strains of DT208 appeared to be predominantly associated with pigs; for the other phage types, the human/food-producing animal relationships of drug-resistant isolates were more complex. For Enteritidis, Virchow, and Hadar, there were substantial differences in the resistance spectra of isolates from humans and food-producing animals, suggesting that food-producing animals bred in England and Wales may not be the primary sources of drug-resistant strains of these serotypes causing infections in humans. Further phenotypic and molecular comparison of drug-resistant isolates of these serotypes may be required to ascertain the sources of strains responsible for infections in humans.

Epidemiology and characterization of animal Salmonella enterica subspecies Enterica serotype typhimurium DT104 in Hungary.

Reports on the internationally emerging significance of multiresistant zoonotic Salmonella in animals and man prompted studies to estimate the significance of multiresistant Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) phage type DT104 of animal origin in Hungary. A collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrofloxacin, nalidixic acid, streptomycin, tetracycline and sulphamethoxazole). Strains with resistance against 3 or more were defined as multiresistant. All strains were phage typed using Felix-Callow's S. Typhimurium phage typing system, and 91 of them (suspect DT104) were also typed according to Anderson's definitive typing (DT) system. In this study, 14% of animal strains from 1997-1998 was classified as DT104, for which turkey, pig and duck seemed to be the main carriers, and the multiresistant non-DT104 strains represented a further 6% of this collection. The prevalence of DT104 was highest among strains of turkey origin (50%), followed by strains of pig (29%), chicken (25%), duck (19%), and goose (3%) origin. The other DT104 related phage types (DT12 and U302) were only detected in the case of 4 strains (2 of porcine, and one each of turkey and of goose origin). The DT104 corresponded to the Felix-Callow types 2/3 or 2c/3 in each case, except in the case of 3 turkey strains where they corresponded to type 35/3. Nalidixic acid resistance was detected in all multiresistant turkey strains and in some of other animal origin but none of these strains were resistant to enrofloxacin. A retrospective analysis (based on the above relationship) indicated that S. Typhimurium strains corresponding to DT104 could be present and increase in the Hungarian farm animal population from about 2% to 20% between 1985 and 1990, in a manner similar to the emergence of human DT104, as reported elsewhere (Pászti et al., 2000). The 91 suspect DT104 strains were also tested for plasmid profile and for spvC gene indicating the presence of the large serotype specific plasmid (Ssp). No characteristic plasmid profile could be attributed to S. Typhimurium DT104. The serovar-specific large plasmid was detected by PCR for spvC in 100% of DT104 strains and in 77% of the non-DT104 strains. The virulence of two DT104 strains was tested in orally infected day-old chicks and compared with virulence of 4 non-DT104 strains. Higher colonizing virulence of DT104 strains could be established as compared to the other strains.