Differentiation of Salmonella typhimurium DT204c by plasmid profile and biotyping

Seventy per cent of the United Kingdom isolates of Salmonella typhimurium from calves are phage type 204c and the study of the epidemiology of this organism requires additional methods of strain characterisation. This paper describes the applications of biotyping and plasmid-profile analysis for this purpose. One hundred and eleven isolates from 73 outbreaks of disease were examined. All belonged to the same primary biotype, although strains from 39 of the outbreaks differed in secondary tests in failing to ferment m-inositol at 25 degrees C. Four different antibiotic resistance patterns were detected among the isolates, which possessed seven distinct plasmid profiles. The spread of a distinct type through the calf marketing chain was investigated by using these techniques.     

Survey of the prevalence of warble fly larvae in market cattle in Great Britain

A survey of warble-infested 'fat' cattle in 57 selected livestock markets in Great Britain was carried out during June 1972 and during May each year from 1973 to 1984. The annual total number of cattle inspected varied from 41,587 to 60,481. The level of infestation increased from 22.3 per cent in 1972 to 38.0 per cent in 1976 and then declined slightly to 34.3 per cent in 1978. Following the introduction of legislation and the warble fly eradication campaign in 1978 there was a rapid decrease to 8.6 per cent infestation by 1979 and by 1984 the level was less than 0.02 per cent.     

Bloat of cattle in Britain

Extract

The opportunity to give you some ideas upon the condition of bloat as it occurs in England is welcomed. The method of approach suggested here is that of the late Sir James Mackenzie, “The Beloved Physician,” England's most celebrated clinical worker of the first war period. In assessing and solving unknown clinical entities, his method of arriving at a diagnosis is exceedingly useful. It resulted in his famous discovery of the A-V Bundle in the heart. Briefly, where the condition can be limited to a particular organ or set of organs, the primary interference is narrowed down to either Structural-Functional or Reflex.     

The detection of Salmonella typhimurium varatio copenhagen DT 2 in purebred pigeons

On the occasion of a large exhibition of pure-breed fancy pigeons 398 animals from 49 different dovecotes were examined for Salmonella shedding. Faecal samples were taken after caging of the birds for the exhibition and after 3 days, before the end of the exhibition. Salmonella were detected in faeces of 28 out of 398 pigeons (7.04%). 10 birds were Salmonella positive only after caging for the exhibition, 10 other animals only before the end of the exhibition, and 8 pigeons at both occasions. The Salmonella positive birds originated from 15 different dovecotes, i.e. in ca. 30% of the dovecotes at the exhibition at least 1 Salmonella positive pigeon was identified. The share of positive birds in these dovecotes varied between 5% and 83%. All Salmonella isolates belonged to the serovar Typhimurium variant copenhagen and were of phage type DT 2. The results of this study do not provide complete evidence on the spreading of Salmonella organisms from birds infected at time of caging to other pigeons during the exhibition, however, such transmission cannot be excluded. In only 18 dovecotes pigeons were immunised against Salmonella Typhimurium. However, in these dovecotes all breeder birds but only 13% of the young pigeons had been immunised. Among the vaccinated breeder pigeons the number of Salmonella positive birds was considerably lower (not significant) than among the non-vaccinated breeders. There is epidemiological evidence that vaccination of pigeons has a considerable protective effect against Salmonella exposure. However, in order to effectively reduce Salmonella findings in pure-breed fancy pigeons it is recommended to provide vaccination to pigeons in a greater number of dovecotes and to include the progeny, too.     

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.     

Augmentation of antibiotic resistance in Salmonella typhimurium DT104 following exposure to penicillin derivatives

Antibiotic resistance in pathogenic bacteria has been a problem in both developed and developing countries. This problem is especially evident in Salmonella typhimurium, one of the most prevalent foodborne pathogens. While performing in vitro gentamicin protection-based invasion assays, we found that certain isolates of multiresistant S. typhimurium can be 'induced' to exhibit new resistance profiles. That is, bacteria become resistant to a wider range of antibiotics and they also exhibit quantitative increases in MIC values for antibiotics that were part of their pre-induction antibiograms. This 'induction' process involves growing the bacteria to stationary phase in the presence of antibiotics such as ampicillin, amoxicillin or ticarcillin. Since the isolates studied exhibited resistance to ampicillin, amoxicillin and ticarcillin prior to exposing the bacteria to these antibiotics, the observed phenomenon suggests that resistant Salmonella not only have a selective advantage over non-resistant Salmonella but their resistance phenotypes can be accentuated when an inappropriate antibiotic is used therapeutically.     

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.     

Influence of long-time transportation stress on re-activation of Salmonella typhimurium DT104 in experimentally infected pigs

In this study a Salmonella Typhimurium infection model in swine was used in order to investigate the influence of pre-mortal stress induced by long time period transportation on the re-activation of Salmonella in experimentally infected pigs. Salmonella free pigs were exposed to a highly virulent strain of Salmonella Typhimurium DT104 by direct intragastrical administration. Clinical parameters were monitored and the shedding rate in faeces was qualitatively and quantitatively determined by standard bacteriological procedures for 21 days. The distribution of the challenge organism in 14 different internal organs of transported and nontransported animals was determined. All infected animals developed clinical signs of salmonellosis 12 to 24 hours post infection. About 88 to 100% of the fecal samples were culture-positive up to post exposure day 6, and then varied from 71 to 92% until slaughter, respectively. At necropsy S. Typhimurium was recovered most frequently from caecum and ileocolic lymph nodes (83%), colon (79%), palatine tonsils (71%) and mandibular lymph nodes (62.5%). A negative impact of transportation stress on the shedding rate and the general condition of the animals was observed.     

Molecular characterization, spread and evolution of multidrug resistance in Salmonella enterica typhimurium DT104.

Multidrug-resistant Salmonella enterica serovar Typhimurium phage type DT104 has emerged during the last decade as a global health problem because of its involvement in diseases in animals and humans. Multidrug-resistant DT104 strains are mostly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracyclines (ACSSuT resistance type). The genes coding for such resistances are clustered on the chromosome. This paper reviews new developments in the characterization of S. enterica Typhimurium DT104, its chromosomal antibiotic resistance genes and their spread among other S. enterica Typhimurium phage types and other S. enterica serovars, the development of specific detection methods, virulence characteristics, and the evolution of multidrug-resistance with regard to the emergence of quinolone resistance.     

Identification of factor XI deficiency in Holstein-Friesian cattle in Britain

Blood coagulation tests were performed on dairy cattle in a herd with haemorrhagic problems on a farm in Gloucestershire. The characteristic pattern of prolonged partial thromboplastin time with normal prothrombin time and thrombin time was shown to be associated with a partial factor XI deficiency, a congenital defect previously identified in cattle in North America.     

Increasing prevalence of Mycoplasma bovis in Danish cattle

A study on the prevalence of mycoplasmas in pneumonic bovine lungs was performed on material submitted for diagnostic purposes at the Danish Veterinary Laboratory, Copenhagen. Among the 50 examined cases 43 (86.0%) were found to be infected with mycoplasmas. The predominant mycoplasmas were Ureaplasma spp. (72.0%), M. dispar (48.0%) and M. bovis (24.0%). Other mycoplasmas were M. bovirhinis (20.0%) and M. bovigenitalium (6.0%). Among the infected lungs multiple species infections were predominant (76.7%) over single species infections (23.3%) with M. dispar-Ureaplasma (25.6%), M. bovis-Ureaplasma (18.6%) and M. dispar-M. bovirhinis-Ureaplasma (11.6%) infections being the most frequently encountered combinations. There appears to be an increasing prevalence of M. bovis (24.0%) as compared to earlier reports (0.6-2.0%), thus calling for special attention upon this mycoplasma. Pulsed field gel electrophoresis (PFGE) analysis of 11 field isolates of M. bovis from 9 different farms revealed different profiles except for 2 isolates which were recovered from the same farm. Because mycoplasmas belonging to the 'M. mycoides cluster' were not encountered during this study; it appears that the Danish cattle population is still free from this group of mycoplasma in spite of their presence in some other European countries.     

Effect of a variant infectious bursal disease virus (E/Del) on Salmonella typhimurium infection in commercial broiler chickens

The effect of infectious bursal disease virus (IBDV) on Salmonella typhimurium (ST) infections in broilers was investigated in terms of Salmonella shedding and persistence, pathogenicity, and isotype specific humoral immune responses. Thirty-six, 1-day-old, straight-run commercial broiler chickens that were Salmonella negative by polymerase chain reaction (PCR) and culture were divided into two groups of 18 chicks each (ST and ST-IBDV). One group (ST-IBDV) of chicks received the E/Del strain of IBDV (10(5.0) median tissue culture infective dose [TCID50]/ml) through the ocular and cloacal routes divided into doses of 50 microl each at 2 days of age. Both groups were then inoculated with 10(8) colony-forming units (CFU)/ml nalidixic acid-resistant ST in the drinking water at 3 days of age. Environmental Salmonella counts were higher in the ST-IBDV group at 2 and 3 wk postinfection (PI) compared to the ST group. ST carriage in the cecal contents between the ST and ST-IBDV groups was not statistically different. The ST-IBDV group had a single mortality at 10 days postinfection compared to none in the ST group. The ST-IBDV group had significantly lower bursa to body weight ratios at 4 and 6 wk, as well as higher bursal lesion scores than the ST group at 2, 4, and 6 wk PI. The ST group had significant increase in serum IgG from 2 to 6 wk PI in comparison to the ST-IBDV group, which had no significant changes over time. Both IgA and IgM were significantly increased at 4 and 6 wk relative to 2-wk levels. There was an IBDV-induced failure of anti-Salmonella IgG seroconversion over time in ST-IBDV. Both groups continued to shed high levels of Salmonella up to the end of the study despite high antibody levels in the ST group and an unimpaired IgM and IgA production in the ST-IBDV group, indicating a limited influence of humoral immunity on Salmonella clearance.     

The value of embryo transfer to cattle breeding in Britain

An analysis is made of the maximum expenditure which could be justified in embryo transfer in cattle is used to: increase the rate of genetic improvement of dairy or beef cattle; increase the frequency of twin-pregnancies; and expedite a change of breed. Estimates of maximum justifiable expenditure have been compared with an estimate of the cost of non-surgical transfer. Embryo transfer should be used in elite beef herds to increase selection intensity, particularly if bulls from such herds can be used for artificial insemination. Other commercial applications will not be economically justifiable until the cost of transfer has fallen by 50 to 80 per cent.